Proceedings+of+the+6 HelmholtzRetreat · 2015. 12. 1. · Scienﬁcdirector Prof.+Dr.+F.A.J.+Verstraten+ UtrechtUniversity Membersof(the(board(of(the(Helmholtz(Research(School Prof.+Dr.+J.J.+Bolhuis+

Proceedings of the 6th Helmholtz Retreat

6-‐8 June 2012Bergen, The Netherlands

Scien&fic director

Prof. Dr. F.A.J. Verstraten Utrecht University

Members of the board of the Helmholtz Research School

Prof. Dr. J.J. Bolhuis Utrecht UniversityProf. Dr. C.J. Erkelens Utrecht University Prof. Dr. M.A. Frens University Medical Center RoMerdamProf. Dr. A.M.L. Kappers Utrecht UniversityProf. Dr. C. Kemner Utrecht UniversityProf. Dr. J.L. Kenemans Utrecht UniversityProf. Dr. A. Postma Utrecht UniversityProf. Dr. J.B.J. Smeets VU University AmsterdamProf. Dr. J. van der Steen University Medical Center RoMerdamProf. Dr. F.A.J. Verstraten Utrecht University

Members of the board of the Helmholtz Ins&tute

Prof. Dr. J.J. Bolhuis Utrecht UniversityProf. Dr. C.J. Erkelens Utrecht UniversityProf. Dr. A.M.L. Kappers Utrecht UniversityProf. Dr. C. Kemner Utrecht UniversityProf. Dr. J.L. Kenemans Utrecht UniversityProf. Dr. A. Postma Utrecht UniversityProf. Dr. F.A.J. Verstraten Utrecht University Scien&fic advisory council

Prof. Dr. D. Ballard University of Texas, USAProf. Dr. A. Berthoz College de France, Paris, FranceProf. Dr. H. Bülthof Max Planck InsUtute for Biological CyberneUcs, Tübingen, GermanyProf. Dr. J.J. Eggermont University of Calgary, CanadaProf. Dr. A.D. Milner University of Durham, UKProf. Dr. Ch.M.M. de Weert Radboud University Nijmegen, The Netherlands

Office management

Mrs. E. Simcox Utrecht University

Organizers Retreat

staffDr. Chris Paffen Utrecht UniversityDr. Stefan Van der SUgchel Utrecht UniversityProf. Dr. Frans Verstraten Utrecht UniversityHelmholtz PhD councilAlyanne de Haan Utrecht UniversityAnouk Keizer Utrecht UniversityDevika Narain VU UniversitySjoerd Stuit Utrecht UniversityCarlijn van den Boomen Utrecht UniversityVonne van Polanen Utrecht University

Proceedings of the 6th Helmholtz Retreat

6-‐8 June 2012

BergenThe Netherlands

Contents

.................................................................................................Welcome 6

..................................................................................................Program 7

...............................................................................................Keynotes 10

.................................Professor Jean Vroomen, Tilburg University 10

.................................Professor Lex Wertheim, Utrecht University 10

..........................Professor Karl Gegenfurtner, Giessen University 11

......................................................................Special Event: Top Papers 12

..........................................................................Abstracts Talk Sessions 15

......................................................................Wednesday, June 6 15

..........................................................................Thursday, June 7 19

...............................................................................Friday, June 8 23

.......................................................................Abstracts Poster Session 27

.................................................................................List of ParFcipants 35

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Welcome

Professor Frans Verstraten, Utrecht UniversityChairman of the board of the Helmholtz InsCtute

As you all know, we recently lost one of our most prominent members: professor Maarten Bouman. His role in the history of science is internaConally known and acknowledged. The many obituaries show a deep respect for his ideas and contribuCons. In the year he passed away, I was lucky to have several discussions with Maarten and he expressed a deep concern about the way science is evolving, especially in the Netherlands. The word valorizaCon has become the most heard, yet least understood,

word at the coffee table. As the founding father of the TNO insCtute for PercepCon and as such basically responsible for probably many of the most useful applicaCons of fundamental research, he was convinced – like many others – that valorizaCon has more to do with making money in the short run than about accountability for tax payers’ money spent on fundamental research. Given this Zeitgeist, the Helmholtz School has to look into the future and we will. We all know that the decline of naConal research schools in favor of university-‐based equivalents has had its impact on our Helmholtz School as well. Although nobody has ever been able to give a good reason for this strange move, we are all aware that there is only so much one can do to resist these policies. The good thing is that we are here at this retreat irrespecCve of all the poliCcs. We know how science works and we will have excellent presentaCons and lots of discussion. There is no applied science without fundamental research. Helmholtz knew it, Maarten Bouman knew it, and we know it! As a rule, one Zeitgeist will be replaced by another Zeitgeist. The spirit of the Helmholtz insCtute, let’s call it Bouman’s legacy, will however persist! So, welcome to this retreat. Of course a special welcome to our keynote speakers, Karl, Jean and Lex. Enjoy!

Proceedings of the 6th Helmholtz Retreat 6-8 June 2012

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ProgramWednesday 6 June

9.30 Arrival, coffee/tea & cake

11.00 – 11.15 Opening by Frans Verstraten (chairman of the board)

Session 1: Behavioral Biology / Physics of man, Utrecht University

11.15 – 11.35 Sanne Moorman – Lee-‐hemispheric dominance in birdsong learning and memory11.35 – 11.55 Charlofe Lindeyer – Vasotocin, a nonapepCde, influences zebrafish shoaling behaviour11.55 – 12.15 Virjanand Panday – Bimanual integraCon of curvature12.15 – 12.35 Vonne van Polanen – The saliency of compliance in a hapCc search task

12.35 – 14.00 Lunch & sniff-‐some-‐good-‐air-‐Cme

Session 2: Department of Neuroscience, Erasmus Medical Center

14.00 – 14.20 Melisssa Batson – When your cogniCve itch needs scratching, ask your cerebellum!14.20 – 14.40 Eric Avila – Efficacy of smaller electrode configuraCon for cerebellar transcranial direct current sCmulaCon on motor and saccade adaptaCon learning14.40 – 15.00 Casper de Boer -‐ Visuomotor impairments in Alzheimer’s disease15.00 – 15.20 Rudolf Burggraaf – The effect of mulCple observers on search performance

15.20 – 15.40 Refreshments/coffee & tea

Special event: Top papers

15.40 – 16.00 Jack van Honk – Testosterone: a hormone misunderstood16.00 – 16.20 Jeroen Smeets – Temporal uncertainty separates flashes from their background during saccades16.20 – 16.40 Ben Harvey -‐ The relaConship between corCcal magnificaCon factor and populaCon recepCve field size in human visual cortex: constancies in corCcal architecture16.40 – 17.00 Johan Bolhuis – Twifer evoluCon: Brains for birds and brats 17.30 – 19.00 Diner

Keynote lecture 1

19.00 – 20.00 Keynote lecture by Professor Jean Vroomen (Tilburg University) Ctle: ReflecCons of the legacy of Paul Bertelson Poster session

20.00 Organized by the Helmholtz PhD Student Council


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Thursday 7 June

06.00 – 07.00 Early bird walk/run/swim07.00 – 08.45 Breakfast

Session 3: Neuropsychology group, Dept. of Experimental Psychology, Utrecht University

09.00 – 09.20 Rudmer Menger – Reaching into the danger zone: specific Target-‐Distractor Similarity effects in Obstacle Avoidance during a Reach-‐to-‐grasp task09.20 – 09.40 Nathan van der Stoep – Audio-‐visual processing in near-‐ and far-‐space09.40 – 10.00 Neeltje Kant – ProspecCve memory funcConing in stroke paCents10.00 – 10.20 Linda Schoo – Episodic memory of content and temporal order: effects of cerebral stroke

10.20 – 11.00 Coffee/tea

Keynote lecture 2

11.00 – 12.00 Keynote lecture by Professor Lex Wertheim (Utrecht University) Ctle: Seeing moCon

12.00 – 13.30 Lunch & sniff-‐some-‐fresh-‐air-‐Cme

Session 4: Human Movement Science, VU University Amsterdam

13.30 – 13.50 Leonie Oostwoud Wijdenes – CharacterisCcs of fast online movement correcCons13.50 – 14.10 Rebekka Verheij – Why are grasping movements curved in the verCcal plane?14.10 – 14.30 Devika Narain – PredicCon and learning in sensorimotor control14.30 – 14.50 Nienke Debats – Moving the Weber fracCon: the perceptual precision for moment of inerCa increases with exploraCon force.

14.50 – 17.00 Sniff-‐some-‐fresh-‐air-‐Cme

Special event: Helmholtz Pub Quiz

17.00 – 17.45 Organized by the Helmholtz PhD Student Council

17.45 – 19.15 Diner

Keynote lecture 3

19.15 – 20.15 Keynote lecture by Professor Karl Gegenfurtner (Giessen University) Ctle: Where we look determines what we see: effects of eye movements on lightness percepCon


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Friday 8 June

06.00 – 07.00 Early bird walk/run/swim07.00 – 08.45 Breakfast

Session 5: Experimental Psychology group, Dept. of Experimental Psychology /Physics of Man, Utrecht University

09.00 – 09.20 Tobias Borra -‐ An octave effect in auditory afenCon09.20 – 09.40 Maartje C. de Jong -‐ Perceptual experience modulates corCcal circuits involved in visual awareness09.40 – 10.00 Vivian Holten – Less rigid opCc flow causes more postural sway10.00 – 10.20 Sjoerd Stuit -‐ Disentangling the influences of different cues on perceptual grouping during binocular rivalry

10.20 – 10.40 Coffee/Tea

Session 6: Human Biopsychology and Psychopharmacology group, Dept. of Experimental Psychology, Utrecht University

10.40 – 11.00 Carlijn van den Boomen – On the effects of GABA modulaCon on vision in children11.00 – 11.20 Ivo Heitland – Failure to exCnguish fear is associated with geneCc variability in the human cannabinoid receptor 111.20 – 11.40 Dennis Hofman – Fairness modulates non-‐conscious facial mimicry in women 11.40 – 12.00 Estrella Montoya – Moral reasoning is influenced by testosterone administraCon depending on second-‐to-‐fourth digit raCo

12.00 – 13.30 Lunch & sniff-‐some-‐fresh-‐air-‐Cme

13.30 –… Whatever you feel like…!


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KeynotesProfessor Jean Vroomen, Tilburg University

In our lab, we invesCgate how informaCon from different sense organs is combined so that a coherent representaCon of the world is obtained. We focus on the intersensory integraCon of auditory, visual, and tacCle informaCon in the spaCal, temporal, phoneCc, and emoConal domain. Besides tradiConal behavioral methods, we use ERPs and fMRI with normal subjects and paCents (e.g., blindsight, neglect, schizophrenics). Recently, we also started to look at intersensory integraCon in infants.

The keynote: ReflecFons of the legacy of Paul Bertelson

Abstract: Paul Bertelson (1926-‐2008) was a professor in cogniCve science at the Université Libre de Bruxelles, Belgium and Tilburg University, the Netherlands. He started his carrier with Donald Broadbent (Cambridge) on ‘mental chronometry’, and then moved to Brussels where he worked on topics like the refractory period, Cme order percepCon, cerebral lateralizaCon, spaCal afenCon, spoken word recogniCon, reading, Braille, and illiteracy. In this talk, I will reflect on his mulCsensory work while in Tilburg. I will share some of his insights on the relaCon between vision and audiCon in space, Cme, and speech. I will also show some recent demos that Paul could not experience anymore, but that I am sure of that he would have loved.

Professor Lex Wertheim, Utrecht University

Wertheim (1942) studied psychology at the Hebrew University of Jerusalem in Israel and Groningen University in the Netherlands. A large part of his career was spent at the TNO Human Factors InsCtute in Soesterberg. Apart from his basic research on moCon percepCon, he has been working on a new approach to visual search, and measurement methods to quanCfy the concept of visual conspicuity. He has a strong interest in applied research as well, having collaborated with several internaConal organizaCons of human factors and cogniCve ergonomics.

The keynote: Seeing moFon

Abstract: In this talk a review will be given of the mulCsensory approach to the visual percepCon (no contradicCon implied) of movement, as this is the approach I have taken for the befer part of my scienCfic career. The talk will focus on the empirical paradigm developed to quanCtaCvely measure the size and gain of what is known as the efference copy, the role of neural noise and the effects of concurrent self moCon and vesCbular sCmulaCon. The framework explains well-‐known phenomena as the Filehne illusion (seeing illusory object moCon during eye movements made across the object) and the Aubert-‐Fleishl paradox (object velocity is underesCmated when the object is pursued with the eyes) and some demonstraCons will be given of illusions predicted from the theory.


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Professor Karl Gegenfurtner, Giessen University

The emphasis of my current research is on informaCon processing in the visual system. Specifically, I am concerned with the relaConship between low level sensory processes, higher level visual cogniCon, and sensorimotor integraCon. My goal is to answer the quesCon how complex scenes and objects are perceived in a natural environment, how they are represented in the brain, and how the visual informaCon is used to drive the motor system.

The keynote: Where we look determines what we see: effects of eye movements on lightness percepFon

Abstract: Judging the lightness of visual sCmuli has been studied for centuries. The light reaching the eye is the product of the illuminaCon and the reflectance of the object, and also depends on the scene geometry. However, only the proporCon of reflected light is an invariant property of the object and thus of great importance for vision. There are several well-‐established factors that support lightness constancy in the face of these challenges. On one hand, lateral inhibiCon between reCnal neurons filters out shallow intensity gradients which are mostly due to illuminaCon effects. On the other hand, more complex factors also have an effect on lightness percepCon, such as object shape or the interpretaCon of transparent surfaces. Eye movements, however, have been almost completely neglected so far, even though the visual system does sample the local properCes of objects by moving the eyes around. Since visual acuity, luminance sensiCvity, contrast sensiCvity and color sensiCvity change with reCnal eccentricity, in order to finely analyze the visual scene, our visual system has to sCtch together its representaCon of the world from many small samples. We therefore tested the hypothesis of a link between the local informaCon sampled from those fixaCons and the apparent lightness of an object in a color matching task. Our results show that where we look can have massive effects on percepCon. When observers matched the lightness of natural objects they based their judgments on the brightest parts of the objects, and at the same Cme they tended to fixate points with above-‐average luminance. When we forced parCcipants to fixate a specific point on the object using a gaze-‐conCngent display setup, the matched lightness was higher when observers fixated bright regions. This indicates a causal link between the luminance of the fixated region and the lightness match for the whole object. SimulaCons with rendered physical lighCng show that this fixaCon strategy is an efficient and simple heurisCc for the visual system to arrive at accurate and invariant judgments of lightness.


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Special Event: Top PapersThe 6th Helmholtz Retreat will host a new session named ‘top papers’. For this session we selected scienCfic work that received much afenCon and was published in high-‐impact journals in the last year, and was published by members of the Helmholtz InsCtute.

The session will host the following four talks:

15.40 – 16.00 Jack van Honk – Testosterone: a hormone misunderstood

Testosterone is thought to be an evil hormone, responsible not only for social aggression, but also for greed and thus the economical crisis. Wrongly as there are no good or bad hormones, and the effects of hormones such as testosterone on social behavior differ between individuals and situaCons. Here we show that individual differences in prenatal levels of testosterone (measured by the right-‐hand's second-‐to-‐fourth digit-‐raCo) are strongly predicCve for effects of testosterone on both cogniCve empathy and social cooperaCon. High-‐prenatal testosterone exposure (low 2D:4D) boosts the negaCve impact of testosterone administraCon on cogniCve empathy in a mind reading task, whereas in subjects with low prenatal testosterone we demonstrate posiCve effects of testosterone administraCon on social cooperaCon in a neuroeconomic task. Notably, 2D: 4D is interacCvely shaped by the male sex steroid testosterone and female sex steroid estradiol in utero, thus high-‐2D:4D points at relaCve low-‐ prenatal testosterone vs. high-‐prenatal estradiol and vice versa. Taken together our data suggest that the balance between the sex steroids prenatally, marked by 2D:4D predicts whether effects of testosterone on social behavior in later life will be posiCve or negaCve in nature.

The presentaCon is based on:

• van Honk J., Motoya E.R., van Vugt M., Bos P.A., & Terburg D. (in press). 2D: 4D moderates effects of testosterone on social cooperaCon. Nature.

• van Honk J., Schufer D.J., Bos P.A., Kruijt A.W., Lentjes E.G., & Baron-‐Cohen S. (2011). Testosterone administraCon impairs cogniCve empathy in women depending on second-‐to-‐fourth digit raCo. Proceedings of the NaJonal Academy of Sciences USA, 108, 3448-‐3452.

• van Honk J., Terburg D., & Bos P.A. (2012). Further notes on testosterone as a social hormone. Trends in CogniJve Sciences, 15, 291-‐292.

16.00 – 16.20 Jeroen Smeets – Temporal uncertainty separates flashes from their background during saccades

It is known that spaCal localizaCon of flashed objects fails around the Cme of rapid eye movements (saccades). This mislocalizaCon is oeen interpreted in terms of a combinaCon of shies and deformaCons of the brain's representaCon of space to account for the eye movement. Such temporary remapping of posiCons in space should affect all elements in a scene, leaving ordinal relaConships between posiCons intact. We performed an experiment in which we presented flashes on a background with red and green regions to human subjects. We found that flashes that were presented on the green part of the background around the Cme of a saccade were readily reported to have been presented on the red part of the background and vice versa. This is inconsistent with the noCon of a temporary shie and deformaCon of perceived space. To explain our results, we present a model that illustrates how temporal uncertainty could give rise to the observed spaCal mislocalizaCon. The model combines uncertainty about the Cme of the flash with a bias to localize targets where one is looking. It reproduced the pafern of mislocalizaCon very


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accurately, showing that perisaccadic mislocalizaCon can best be explained in terms of temporal uncertainty about the moment of the flash.


• Maij F., Brenner E., & Smeets J. B. J. (2011). Temporal uncertainty separates flashes from their background during saccades. Journal of Neuroscience, 31(10), 3708-‐3711.

16.20 – 16.40 Ben Harvey -‐ The relaConship between corCcal magnificaCon factor and populaCon recepCve field size in human visual cortex: constancies in corCcal architecture

RecepCve field (RF) sizes and corCcal magnificaCon factors (CMF) are fundamental organizaCon properCes of the visual cortex. At increasing visual eccentricity, RF sizes increase and CMF decreases. A relaConship between RF size and CMF suggests constancies in corCcal architecture, as their product, the corCcal representaCon of an RF (point image), may be constant. Previous animal neurophysiology studies of this quesCon yield conflicCng results. Here we use fMRI to determine the relaConship between the populaCon RF (pRF) and CMF in humans. In average and individual data, the product of CMF and pRF size, the populaCon point image, is near-‐constant, decreasing slightly with eccentricity in V1. Inter-‐hemisphere and subject variaCons in CMF, pRF size, and V1 surface area are correlated, and the populaCon point image varies less than these properCes. These results suggest a V1 corCcal processing architecture of approximately constant size between humans. Up the visual hierarchy, to V2, V3, hV4 and LO1, the populaCon point image decreases with eccentricity, and both the absolute values and rate of change increase. PRF sizes increase between visual areas and with eccentricity, but when expressed in V1 corCcal surface area, i.e. corCco-‐corCcal pRFs, they are constant across eccentricity in V2/V3. Thus V2/V3, and to some degree hV4, sample from a constant extent of V1. This may explain populaCon point image changes in later areas. Consequently, the constant factor determining pRF size may not be the relaConship to the local CMF, but rather pRF sizes and CMFs in visual areas from which the pRF samples.


• Harvey B.M., & Dumoulin S.O. (2011). The relaConship between corCcal magnificaCon factor and populaCon recepCve field size in human visual cortex: constancies in corCcal architecture. Journal of Neuroscience, 31(38), 13604-‐13612.

16.40 – 17.00 Johan Bolhuis – Twifer evoluCon: Brains for birds and brats

Vocal imitaCon, a prerequisite for the evoluCon of spoken language, is shared with certain marine mammals, parrots, hummingbirds and songbirds, but appears to be absent in non-‐human primates. There are striking behavioural similariCes between auditory-‐vocal learning in human infants and songbirds: auditory learning takes place during a sensiCve period early in development, and there is a transiConal period of early vocalisaCon which is called ‘babbling’ and ‘subsong’, respecCvely. Considering the behavioural, neural and linguisCc evidence, an evoluConary scenario emerges where three factors are important. First, there is neural homology, where similar brain regions and genes are involved in auditory learning and vocal producCon, not only in songbirds and humans, but also in other mammals. Second, there is evoluConary convergence with regard to the mechanisms of auditory-‐vocal learning, which proceeds in essenCally the same way in songbirds and human infants, but not in non-‐human primates. Third, as yet there is no evidence to suggest that non-‐human animals possess the combinatorial complexity of human language syntax. It may be that the neural mechanisms that evolved from a


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common ancestor, combined with the auditory-‐vocal learning ability that evolved in both humans and songbirds, enabled the emergence of language uniquely in the human lineage.


• Berwick R.C., Okanoya K., Beckers G.J.L., & Bolhuis, J.J. (2011). Songs to syntax: the linguisCcs of birdsong. Trends in CogniJve Sciences, 15(3), 113-‐121.

• Bolhuis J.J., Okanoya K., & Scharff C. (2010). Twifer evoluCon: converging mechanisms in birdsong and human speech. Nature Reviews Neuroscience, 11, 747-‐759.


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Abstracts Talk SessionsWednesday, June 6

Session 1: Behavioral Biology / Physics of man, Utrecht University

11.15 – 11.35 Sanne Moorman – Lee-‐hemispheric dominance in birdsong learning and memory

Unlike non-‐human primates, songbirds learn to vocalize much like human infants acquire spoken language. Songbirds learn to sing in two partly overlapping phases: a memorizaCon phase during which they form an internal representaCon (a ‘template’) of the song of their tutor, and a sensorimotor learning phase in which they start to produce their own song. In humans, Broca’s area in the frontal lobe and Wernicke’s area in the temporal lobe are crucially involved in speech producCon and percepCon, respecCvely. We have shown previously that the caudal medial nidopallium (NCM) is a likely neural substrate for the representaCon of tutor song memory in male songbirds. The NCM is thought to be analogous to the auditory associaCon cortex in the human superior temporal lobe, which contains Wernicke’s area. In contrast, Broca-‐like regions in the ‘song system’, including HVC (a lefer-‐based name) were shown to be important for song producCon and song learning. Human brain regions involved in speech and language show characterisCc lee-‐sided dominance in their acCvaCon pafern, already in three month-‐old infants that are exposed to speech. Moreover, a memory-‐specific lee-‐sided dominance in Wernicke’s area for speech percepCon has been demonstrated in 2.5 month-‐old babies. Here, we invesCgated whether there is similar song memory-‐related lateralizaCon in the songbird brain. We exposed male zebra finches to tutor or unfamiliar song. We found lee-‐sided dominance of neuronal acCvaCon in the HVC of juvenile and adult zebra finch males, independent of the song-‐sCmulus presented. In addiCon, only juvenile males showed lee-‐sided dominance in the NCM when exposed to tutor song, not when exposed to novel song or silence. Thus, hemispheric dominance in the NCM was specific for the song-‐learning phase and memory-‐related. It is possible that auditory-‐vocal learning is associated with hemispheric specializaCon, and that this associaCon arose in songbirds and humans through convergent evoluCon.

11.35 – 11.55 Charlofe Lindeyer – Vasotocin, a nonapepCde, influences zebrafish shoaling behaviour

Social behaviour such as group formaCon is adapCve in many species, for example providing anC-‐predator benefits. Group formaCon can also potenCally affect other processes, such as the transmission of informaCon between individuals. The oxytocin-‐vasopressin nonapepCde families have been shown to influence a wide range of social behaviour paferns, including mate choice and aggression in mammals, and, more recently, flocking in birds. These nonapepCde families appear to be evoluConary conserved in funcCon and structure across vertebrates, suggesCng that they could play a conserved role in group formaCon. To gain insight into such a mechanism mediaCng social behaviours, we studied shoaling behaviour in female zebrafish (Danio rerio), invesCgaCng the influence of isotocin and vasotocin (teleost homologues of the mammalian oxytocin and vasopressin). Zebrafish are a schooling species and while their development and geneCcs are well studied, their behaviour is less well explored. We invesCgated the effects of single peripheral injecCons of vasotocin, isotocin and their antagonists on shoaling preferences. Aeer administraCon, subjects were tested in a two-‐choice-‐paradigm, being offered a choice between a shoal of conspecifics or an empty compartment. We predicted that vasotocin would decrease and isotocin would increase shoaling tendencies. Vasotocin administraCon indeed significantly decreased the Cme subjects spent interacCng with the shoal compared to control


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treatments. In addiCon, vasotocin increased the latency to start shoaling and interacCng with the shoal. However, administraCon of the vasotocin antagonist (an arginine vasopressin receptor 1A antagonist) reduced the Cme fish spent interacCng and shoaling, contrary to expectaCons. Isotocin administraCons did not show clear effects compared to control treatments, although isotocin-‐administered subjects were faster to shoal and interact with the shoal than vasotocin-‐administered subjects. The isotocin antagonist (an oxytocin receptor antagonist) had no significant effects on the measured behaviours. Our results show that administraCon of nonapepCdes, specifically vasotocin, decreases shoaling tendency in a teleost fish. This raises the possibility that this family of pepCdes plays a conserved role across vertebrates in the neural mechanisms underlying sociality.

11.55 – 12.15 Virjanand Panday – Bimanual integraCon of curvature

When holding a basketball or a volleyball, we can not only see, but also feel which one we are holding in our hands, due to a difference in diameter and curvature. So far, the hapCc integraCon of distance and curvature informaCon between two hands has received lifle afenCon. In Experiment 1, distance discriminaCon thresholds were determined for unimanual and bimanual exploraCon of flat surfaces. In Experiment 2, curvature was added. In the unimanual condiCon, subjects were asked to indicate whether the distance between a curved surface and the midsagifal plane was larger or smaller than the corresponding radius of the curved surface. In the bimanual condiCon, subjects were asked to indicate whether the distance between two curved surfaces was larger or smaller than the corresponding diameter of the curved surfaces. We found that there was no significant difference between unimanual or bimanual distance discriminaCon thresholds for flat surfaces. In contrast, bimanual exploraCon of curved surfaces results in lower discriminaCon thresholds than unimanual exploraCon. We conclude that hapCc percepCon of distance is not integrated in bimanual exploraCon, whereas hapCc percepCon of curvature is.

[This work has been parCally supported by the European Commission with the CollaboraCve Project no. 248587, ``THE Hand Embodied", within the FP7-‐ICT-‐2009-‐4-‐2-‐1 program ``CogniCve Systems and RoboCcs"]

12.15 – 12.35 Vonne van Polanen – The saliency of compliance in a hapCc search task

Visual search has proven to be a valid method to invesCgate feature saliency. Similarly, hapCc search reveals efficient percepCon of hapCc properCes. In this study, the saliency of hardness and soeness was invesCgated in a search task. In Experiment 1, parCcipants had to grasp a bundle of spheres and determine whether a hard target was present among soe spheres or vice versa. When the difference in compliance between target and distractors was small, a serial strategy was found and reacCon Cmes increased with the number of items. With a large difference in compliance, the reacCon Cmes did not depend on the number of items and a parallel strategy was found. In Experiment 2, parCcipants had to press their hand on a display filled with hard and soe spheres. In the search for a soe target the slopes of reacCon Cmes against the number of items were high, but the locaCons of target and distractors had a large influence on the search difficulty. With a hard target, the reacCon Cme was independent of the number of items. This showed that weight cues did not cause the finding in Experiment 1 and that both hardness and soeness are salient features.


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Session 2: Department of Neuroscience, Erasmus Medical Center

14.00 – 14.20 Melisssa Batson – When your cogniCve itch needs scratching, ask your cerebellum!

The cerebellum is commonly viewed as playing a large role in motor learning, mainly through supervision and update of egocentric models of expected and perceived results of an acCon. Recent studies suggest that corCco-‐cerebellar loops involved in motor-‐learning may play a role in non-‐motor tasks, such as tasks requiring execuCve funcCon. Many execuCve funcCon deficits seen in paCents with PFC damage, including difficulCes with spaCal cogniCon, planning and set-‐shieing, are also seen in cerebellar paCents; yet it is sCll unclear how PFC-‐cerebellar connecCons influence non-‐motor prefrontal funcCons. To invesCgate this relaConship, we have devised a complex prefrontal-‐funcCon test by combining the Wisconsin Card SorCng Task with the Iowa Gambling Task. This task invesCgates the role of the cerebellum in forming “habits”, defined as learning to choose the best match from a set of ambiguously rewarded choices, based on the parCcipant’s inferred value of that choice of acCon. Behaviour was modeled to differenCate when a parCcipant has learned the best match of the game versus when they are sCll searching for the best match (“unlearned”). Cerebellar and prefrontal acCvity was invesCgated at various decision-‐making stages (card-‐viewing and reward-‐viewing) and condiCons (instructed and uninstructed match-‐making) using funcConal MRI. FuncConal images were preprocessed and run through a GLM contrasCng learned versus unlearned events and, separately, uninstructed versus instructed events. Data were analysed using SPM8, and the SUIT and funcConal connecCvity toolboxes. Preliminary data suggests that connecCvity between Crus 1 of the right cerebellar hemisphere is more acCvely engaged with prefrontal cortex while viewing the card aeer the rule has been learned, rather than while subjects are searching for the best rule; suggesCng a role of the cerebellum in automaCng decisions into habits.

14.20 – 14.40 Eric Avila – Efficacy of smaller electrode configuraCon for cerebellar transcranial direct current sCmulaCon on motor and saccade adaptaCon learning

Transcranial direct current sCmulaCon (tDCS) is a form of non-‐invasive sCmulaCon where a weak current is applied through electrodes over the scalp and is known to induce changes in neuronal excitability in a polarity-‐specific manner, hence effecCng motor behavior and cogniCve funcCons. Smaller electrode configuraCons may be beneficial to the efficacy of this treatment, as suggested through modeling, and human studies show that this feature increases focality of sCmulaCon. The aim of our study was to evaluate the impact of tDCS with a reduced contact area over the cerebellum on learning effects during an outward saccadic adaptaCon task and adaptaCon to a novel visuomotor transformaCon task. In the first one, parCcipants had to perform a horizontal visually guided saccade in which every trial a target changed its posiCon (outward) aeer saccade onset (visual saccadic suppression) driving the parCcipant to increase their saccade amplitudes over trials (adaptaCon). On the visuomotor transformaCon task, subjects had to perform ballisCc movements to pseudo-‐random targets shown on screen. Aeer a certain number of trials, a 30-‐degree counter-‐clockwise deviaCon (visuomotor transformaCon) was introduced between the hand movement and the cursor movement, prompCng the subjects to correct for that error in order to reach the targets. Pilot data suggest that applying anodal cerebellar tDCS expedites adaptaCon to visuomotor transformaCons with respect to sham sCmulaCon and adaptaCon might be slightly stronger when applying it in an outward saccade adaptaCon task. These results lead to the belief that tDCS can be used to enhance cerebellar funcCon, such as visuomotor learning, and that small electrode configuraCon is efficient for modulaCon of cerebellar funcCon. tDCS could help lead the way to a befer understanding of motor learning and how the cerebellum is parCcipaCng in this process; therefore, more studies are needed to elucidate the extent to which tDCS can modulate cerebellar funcCons.


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14.40 – 15.00 Casper de Boer -‐ Visuomotor impairments in Alzheimer’s disease

Although memory complaints are one of the first clinical symptoms in paCents with Alzheimer’s disease (AD), damage to the parietal lobe, a key structure in the visuomotor coordinaCon network, was recently idenCfied in early-‐stage AD paCents. The aim of this study was to quanCfy visuomotor coordinaCon in paCents with probable AD and to compare their visuomotor performance with controls using five eye-‐hand coordinaCon tasks of variable cogniCve complexity. Eye and hand movements were measured from 16 AD paCents and 18 controls. The measurement setup consisted of a touch screen, an eye-‐tracking device and a moCon capturing system. We invesCgated eye-‐hand coordinaCon by quanCfying absolute and relaCve latencies of eye and hand movements and by analyzing eye and hand kinemaCcs. We found that AD paCents need significantly more Cme to iniCate and execute goal-‐directed hand movements. AD paCents are also unable to suppress reflexive eye movements and, to a lesser extent, hand movements. Furthermore, AD paCents use a stepwise approach of eye and hand movements to touch a sequence of sCmuli, whereas controls more oeen show an anCcipatory approach. The impairments in reflex suppression of eye and hand movements, and changes in relaCve Cming of eye-‐hand coordinaCon, in AD paCents support the noCon that corCcal networks involving the posterior parietal cortex are affected at an early disease-‐stage. The findings in this study suggest that quanCficaCon of visuomotor coordinaCon can be used in early stage diagnosCcs of AD. Our current research focuses on confirming this hypothesis, not only in AD paCents but in a variety of neurodegeneraCve paCents.

15.00 – 15.20 Rudolf Burggraaf – The effect of mulCple observers on search performance

The call for 'all hands on deck' suggests that in manual tasks there is an expectaCon that results will improve with an increase in the number of helping hands. Could one anCcipate that similarly increasing the number of helping eyes will improve the performance of visual search tasks such as scanning images at an airport security gate?This research used data generated by an experiment with 301 observers each performing 100 search trials. SimulaCons were run of groups of simultaneously searching observers, unaware of other observers performing the same task. The group sizes varied between 1 and 100 observers. This was done by randomly selecCng the required number of observers from the database. Group performance per search trial was determined by the shortest reacCon Cme along with the correctness of that answer.Analysis of the results showed that increasing the number of observers led to a decrease in reacCon Cme. For instance a group size of thirty demonstrated a reacCon Cme of 0.7 seconds compared to a single observer reacCon Cme of 2.4 seconds, but with an unaltered fracCon of correct responses. The fracCon of correct responses, interesCngly, showed a maximum at a group size of five observers with a reacCon Cme already 50% shorter than that of a single observer.Conclusion: The results of a visual search task improve only to a certain extent with an increase in the number of observers. A group size of five resulted in the highest fracCon of correct responses with a decrease in reacCon Cme of 50% compared to a single observer. Groups of more than 30 observers performed faster but with an even smaller fracCon of correct responses compared to the single observers.


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Thursday, June 7

Session 3: Neuropsychology group, Dept. of Experimental Psychology, Utrecht University

09.00 – 09.20 Rudmer Menger – Reaching into the danger zone: specific Target-‐Distractor Similarity effects in Obstacle Avoidance during a Reach-‐to-‐grasp task

The introducCon of non-‐target objects into a workspace leads to temporal and spaCal adjustments of reaching trajectories towards a target. This is because target and distractor compete for afenCon during acCon planning. It is believed that the inadequate resoluCon of that compeCCon influences the movement. There have been several invesCgaCons into how this compeCCon can be modulated by manipulaCng features that are low-‐level properCes of the distractor, like size and orientaCon. On the contrary, lifle is known about the influence of higher-‐level features, like target-‐distractor similarity. In eye movement studies such features of distractors have been revealed to influence oculomotor compeCCon. Because of the Cght neural coupling between the gaze and reaching system, our aim was to determine the contribuCon of target-‐distractor similarity to avoidance movements. We performed two experiments where parCcipants had to reach to grasp a target object while distractors were present in the workspace. These could be either similar or dissimilar in color to the target. The results indicate that target-‐distractor similarity has an effect on reaching-‐to-‐grasp movements. This effect was driven by a specific distractor locaCon relaCve to the reaching hand. We propose that parCcipants afended more to this specific locaCon, or ‘danger zone’, and that compeCCon between target and distractor was enhanced here.

09.20 – 09.40 Nathan van der Stoep – Audio-‐visual processing in near-‐ and far-‐space

In this study we invesCgated unimodal and bimodal processing in both regions of space. Based on literature, we expected audio-‐visual integraCon to be stronger in far-‐space compared to near-‐space. In addiCon, we expected unimodal auditory processing to be dominant in far-‐space, whereas we expected unimodal visual processing to be dominant in near-‐space. This would result in differences in response Cmes on a choice response task. Response Cmes were analyzed using cumulaCve distribuCon funcCons and audio-‐visual response Cmes were tested against staCsCcal facilitaCon (i.e. a race model). Preliminary results showed that when sCmuli are controlled for visual angle and sound pressure level, there are no differences in the strength of integraCon of audio-‐visual sCmuli between near-‐ and far-‐space. This suggests that not space but sCmulus intensity might drive differences in strength of audio-‐visual integraCon in near-‐ and far-‐space. We did find a significant interacCon between space and modality of unimodal sCmuli, with shorter auditory response Cmes in far space compared to near space and the opposite pafern for visual sCmuli. Plans for studies on integraCon differences in near-‐ and far-‐space in a neuropsychological populaCon with near-‐, far-‐, or near-‐ and far-‐space impairments are discussed.

09.40 – 10.00 Neeltje Kant – ProspecCve memory funcConing in stroke paCents

An oeen heard complaint of stroke paCents is their inability to carry out acCons they intent to execute in the future: a failure of what in literature is referred to as prospecCve memory. Research in healthy parCcipants on this subject indicates that mulCple cogniCve components are involved (i.e. intenCon-‐formaCon, retenCon, iniCaCon and execuCon), mostly relying on execuCve and memory funcCons. However, the direct relaCon between prospecCve memory and these funcCons remains unclear. Also, studies on the nature and extent of prospecCve memory (dys)funcConing aeer brain damage are scarce. To gain insight in funcConal and neural correlates of prospecCve memory, we tested 42 chronic stroke paCents (6-‐36 months post stroke) and


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compared their cogniCve profile with 60 matched healthy control parCcipants. ExaminaCon included standard neuropsychological measures of execuCve funcConing, working memory and verbal learning, as well as experimental tasks measuring temporal and spaCal episodic memory and Cme percepCon. ProspecCve memory was assessed with a newly designed paradigm using a conCnuous performance test as ongoing task and parallel Cme-‐ and eventbased prospecCve memory trials, and more naturalisCc tasks adapted from the Rivermead Behavioral Memory Test (RBMT). Preliminary analyses indicate that prospecCve memory is more oeen impaired than retrospecCve memory in stroke paCents. Moreover, divided afenCon, working memory, Cme percepCon and mental speed contribute to prospecCve memory performance. The influence of these separate components on prospecCve memory funcConing will be further invesCgated, and anatomical dissociaCons will be elaborated on. ImplicaCons of these findings will be discussed.

10.00 – 10.20 Linda Schoo – Episodic memory of content and temporal order: effects of cerebral stroke

Episodic memory is thought to link the memories of the what, where, and when of experienced events. Contrary to ‘real world’ episodic memory, standard episodic memory tests mostly consist of intenConal learning paradigms using items with lifle personal Cme-‐related relevance. It is unknown whether item and temporal order memory are intrinsically related or can be funcConally dissociated. We studied item and temporal order memory in paCents with a recent stroke and in a group of healthy subjects.Thirty controls and 41 paCents completed 12 neuropsychological tests. Immediately aeer the administraCon of these tests, parCcipants were offered 18 cards of which 12 reflected the tests performed and six were distracters. ParCcipants were asked to reconstruct the test sequence. Number of hits (selected targets), misses (non-‐selected targets) and false alarms (selected distractors) were registered. Measurements were: Hits [0 -‐ 12] and False Alarms [0 -‐ 6]. A Hits – FA [-‐6 -‐ 12] score was calculated as a measure of signal detecCon.No significant differences were found on the item idenCficaCon score between paCents and controls. In contrast, for the temporal order score, 2 out of 30 controls showed a deficient score, while 10 out of 41 paCents showed a temporal deficiency. For the paCent group the item idenCficaCon scores correlated significantly with the compound domain score of the domain execuCve funcConing, r = .44, p = .004. The Temporal scores correlated significantly with the compound domain scores of the domains memory (r = .43, p = .005) and execuCve funcConing (r = .44, p = .005). We conclude that item memory and temporal order memory can be easily examined as separate enCCes, and that item and temporal order memory of personally experienced events could be dissociable. Together, these results give new insights in the funcConal architecture of episodic memory.

Session 4: Human Movement Science, VU University Amsterdam

13.30 – 13.50 Leonie Oostwoud Wijdenes – CharacterisCcs of fast online movement correcCons

When we make a hand movement to a target that suddenly changes its posiCon, the movement can be adjusted so that the hand will end close to the new posiCon. To understand more about the characterisCcs of these movement adjustments, we invesCgated the influence of different target jump properCes on the characterisCcs of the response. We examined how quickly the movement adjustments were iniCated and how vigorously they were executed. Results indicate that the latency of the response is independent of Cming, direcCon, amount and predictability of the target jumps, but decreased when moCon informaCon was disturbed. The Cming of the perturbaCon and the availability of moCon informaCon influenced the intensity of the response. If


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target jumps occurred later during the movement, the correcCve responses were more intense. Disturbance of moCon informaCon of the jump decreased the responses intensity. These variaCons in intensity were prominent for target jumps perpendicular to the movement direcCon; for target jumps in the direcCon of movement the intensity of the response was marginally influenced. Instead the main adjustment was observed in the movement Cme. Thus the iniCaCon of the correcCve response only considers informaCon about the target. The execuCon of the correcCve response also considers the Cming of the movement to suit the response to the circumstances.

13.50 – 14.10 Rebekka Verheij – Why are grasping movements curved in the verCcal plane?

When humans make grasping movements their digits generally move higher than the starCng posiCons or the posiCons at which they end on the target object, so that the digits' paths are curved when viewed from the side. Recently we published a model to gain more insight into the kinemaCcs of grasping movements. In this model the ‘digits’ curved upward because the table was considered as an obstacle. In order to find out whether a strategy to avoid contacCng the table indeed causes the curvature we performed an experiment. We found that the presence of a table does not cause the curvature. Therefore we experimentally tested other possible explanaCons for the curvature: a strategy to deal with gravity, the movement constraints at the start and end of the movement and a general tendency to curve upward regardless of the objects in the environment. The proposed strategy to deal with gravity cannot explain our experimental results. Together the constraints at the start and end of the movement and a general tendency to curve upward can accurately explain our experimental results. We thus conclude that the constraints at the start and end of the movement together with a general tendency to curve upward cause the curvature in the verCcal plane. Of these three components, the constraints at the start are most influenCal.

14.10 – 14.30 Devika Narain – PredicCon and learning in sensorimotor control

Humans possess remarkable tendencies in learning the staCsCcs of environmental variables and adapCng to them. Literature has shown us the role of combining a priori informaCon with observaCon in order to formulate a predicCon. In our first study, we invesCgate how humans change their predicCon based on observed changes in the environment. In order to do so, we devise an experiment in which we obtain an online esCmate of the sensorimotor prior for our task, which also represents the parCcipant’s predicCon for subsequent unseen observaCons. We fit several models to the data to determine what dynamics may underlie such behavior. In our second study, we invesCgate how humans refine their predicCon by determining whether relaConships exist between environmental variables, and what they might be. The knowledge of such correlaCons among variables reduces the problem of esCmaCng two independent variables to one, if the mapping between them is known. We explore whether humans learn such correlaCons based on the richness of informaCon and temporal dependencies found in the environment. We find that the richer and more temporally independent the sequence of informaCon, the higher the prospect of learning such dependencies.

14.30 – 14.50 Nienke Debats – Moving the Weber fracCon: the perceptual precision for moment of inerCa increases with exploraCon force

HapCc percepCon of object properCes is based on the perceiver exploring the object by applying forces to it. It is unknown however how the magnitude of these exploraCon forces influences the precision of the hapCc sensory esCmate. To address this quesCon, we determined the Weber fracCon for moment of inerCa (i.e., “angular mass‟) of a hand-‐held rod. This was done under four condiCons in which different amounts of force were used to rotate the rod. We found that the


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Weber fracCon deceased with an increased amount of force used for exploraCon. In other words, high exploraCon force leads to a higher perceptual precision for moment of inerCa. This result highlights exploraCon as a means to acCvely manipulate the reliability of hapCc sensory informaCon. We discuss how our findings can be explained by signal-‐dependent neuromuscular noise, and we propose that force-‐dependent perceptual precision might be a general principle in hapCc percepCon.


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Friday, June 8

Session 5: Experimental Psychology group, Dept. of Experimental Psychology /Physics of Man, Utrecht University

09.00 – 09.20 Tobias Borra -‐ An octave effect in auditory afenCon

Aeer hearing a tone, the human auditory system becomes more sensiCve to similar frequencies than to other tones. Current auditory models explain this by a simple bandpass afenCon filter. Here we demonstrate in three psychophysical experiments that auditory afenCon is much more sophisCcated, as it contains mulCple pass-‐bands around octave-‐related frequencies above and below the cued tone. Intriguingly, this “octave effect” not only occurs for physically presented tones, but even persists for the missing fundamental in complex tones and for imagined tones. Our results suggest neural interacCons combining octave-‐related frequencies, likely located in non-‐primary corCcal regions. We speculate that this connecCvity scheme evolved from exposure to natural vibraCons containing octave-‐related spectral peaks, e.g. as produced by the vocal cords.

09.20 – 09.40 Maartje C. de Jong -‐ Perceptual experience modulates corCcal circuits involved in visual awareness

Successful interacCons with the environment entail interpreCng ambiguous sensory informaCon. To address this challenge it has been suggested that the brain opCmizes performance through experience. We invesCgated whether perceptual experience modulates the corCcal circuits involved in visual awareness. Using ambiguous visual sCmuli we were able to disentangle the co-‐occurring influences of sCmulus repeCCon and perceptual repeCCon. Neuroimaging measures revealed that occipital acCvity related to the processing of the sCmulus is facilitated when the current percept was predominant in the past. We propose that the repeated acCvaCon of visual neurons tuned for the features of prevailing percepts facilitates their later re-‐acCvaCon. In this way knowledge gained from previous experiences can be uClized to enhance the stability of previously experienced percepts.

09.40 – 10.00 Vivian Holten – Less rigid opCc flow causes more postural sway

When we move through our environment we experience opCc flow. Flow paferns typically contain a wide range of velociCes. Radial random-‐dot opCc flow paferns, moving with increasing velocity towards the periphery, result in a percept of coherent ‘rigid’ moCon (De Bruyn & Orban, 1990). This rigidity is much less apparent in radial opCc flow paferns, moving at a single speed. Here we invesCgate to what extent opCc flow rigidity affects posture. We varied the rigidity of 3 radial opCc flow types by manipulaCng their velocity profile (quadraCc-‐speed gradient (Q), linear-‐speed gradient (L), single-‐speed (S)), assuming decreasing rigidity. Four single-‐speed opCc flow velociCes were presented (6, 12, 24 or 48 deg/s), while in speed-‐gradient sCmuli these velociCes corresponded to half the integral of their speed-‐gradient curve. SCmuli (radius 43.5°, duraCon 4s) were presented in pseudo-‐random order, interleaved by dynamic visual noise paferns (duraCon randomly varied between 3.4-‐4.2s). ParCcipants stood on a force-‐plate in a completely dark room. The effect of each opCc flow sCmulus was determined by calculaCng the postural sway on the anterior-‐posterior axis.In general, we find that higher flow velociCes lead to more postural sway. InteresCngly, most sway was observed for the condiCon defined as least rigid. In addiCon, we find an anisotropy in that (QLS) contracCng sCmuli generate more sway than expanding sCmuli. Specifically, for contracCng opCc flow, the largest effect was found for the single-‐speed condiCons, although all QLS sCmuli


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resulted in significant sway. In contrast, for expanding opCc flow, only the single-‐speed condiCons resulted in significant sway. This study demonstrates that posture, measured by body sway, is most affected by contracCng, less rigid opCc flow. This might be explained by interacCons between our visual and sensorimotor systems that are tailored towards compensaCng for rigid (i.e. ‘more natural’) sCmuli.

10.00 – 10.20 Sjoerd Stuit -‐ Disentangling the influences of different cues on perceptual grouping during binocular rivalry

During binocular rivalry, incompaCble dichopCc images compete for perceptual awareness. DichopCc images do not compete for awareness independently when rivalry is insCgated at mulCple locaCons of the visual field. This inter-‐dependence is thought to be the result of perceptual grouping. We use the inter-‐dependence in perceptual dominance to disentangle the effect of different cues on grouping during rivalry. Specifically, the simultaneous dominance of spaCally separated compeCng images can be based on similariCes in their image-‐content as well as which eye they are presented to. We presented spaCally separated rival images such that similar images were either presented to the same or to different eyes. Since rivalry compeCCon can be resolved at mulCple stages along the visual processing hierarchy we also tested whether the influence of different cues depends on the type of images used. In two experiments, we used a perceptual tracking paradigm to measure the duraCons of perceiving either idenCcal versus different orientaCon (Exp_1) or perceiving parts of a face versus parts of a plaid (Exp_2). For rivalling orientaCons (Exp_1), we found eye-‐of-‐origin to be the strongest cue for grouping. In addiCon, image-‐content is also a cue for grouping, as images with idenCcal orientaCons were perceptually dominant together longer than images with dissimilar orientaCons, even when they were presented to different eyes. However, in Exp_2, when faces were in binocular compeCCon with plaids, the influence of the cues reversed. That is, in this experiment image-‐content was the stronger cue for grouping although eye-‐of-‐origin sCll influenced the dominant percept. We are able to directly compare these different contribuCons that originate at different levels of the visual processing hierarchy. Overall, our results show that eye-‐of-‐origin and image-‐content cues can independently affect grouping during rivalry and that their relaCve contribuCons can further be affected by the semanCc content of the compeCng images.

Session 6: Human Biopsychology and Psychopharmacology group, Dept. of Experimental Psychology, Utrecht University

10.40 – 11.00 Carlijn van den Boomen – On the effects of GABA modulaCon on vision in children

Background: Visual processing is modulated by Gamma-‐Aminobutyric Acid-‐ (GABA-‐)ergic inhibiCon between neurons in the brain. Psychopharmacological studies revealed that small changes in GABA levels affect specific visual processes in adults. General anesthesia, applied to induce a reversible unconscious state during surgery, produces larger changes in GABA levels. As is suggested by post-‐hoc cogniCve studies in children, GABAergic modulaCon through anesthesia could have longer-‐lasCng effects on brain funcConing than previously assumed. Aim: In the present study, we directly invesCgated whether GABAergic modulaCon through general anesthesia has long-‐lasCng effects on visual processing in children. Methods: Visual processing was invesCgated in typically developed children (age 4-‐12 years). In a texture segregaCon task, the difference in Event-‐Related PotenCal (ERP) response to homogeneous and checkered sCmuli was invesCgated. In addiCon, behavioral performance on acuity and contrast sensiCvity was measured. Results were compared between before and at two Cme-‐points aeer GABAergic modulaCon through general anesthesia: directly aeer and at one day aeer anesthesia (separate groups). Children were anestheCzed with sevoflurane for urologic procedures under general anesthesia (>30 min) with locoregional analgesia in day care treatment. Results: Directly aeer anesthesia,


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brain acCvity was affected differently for the checkered than homogeneous sCmuli. This effect was no longer present at one day aeer surgery. In addiCon, early non-‐sCmulus-‐specific neural processing was affected at both Cme-‐points. Behavioural measures were not affected by GABAergic modulaCon directly aeer or at 1 day aeer surgery. These results show that GABAergic modulaCon through anesthesia has specific short-‐Cme effects on brain acCvity, of which some last for at least one day. The modulaCon has no effects on acuity and contrast sensiCvity, which suggests that children do not suffer from abnormal behavioral visual processing aeer anesthesia.

11.00 – 11.20 Ivo Heitland – Failure to exCnguish fear is associated with geneCc variability in the human cannabinoid receptor 1

Background: Failure to exCnguish fear can lead to persevering anxiety and has been postulated as an important mechanism in the pathogenesis of human anxiety disorders. In animals, it is well documented that the endogenous cannabinoid system plays a pivotal role in the successful exCncCon of fear, most importantly through cannabinoid receptor 1. However, no human studies have reported a translaCon of this preclinical evidence yet.Methods: In the current study, healthy medicaCon-‐free human subjects (N=150) underwent a fear condiConing and exCncCon procedure in a virtual reality environment. Cued fear and contextual anxiety was assessed with fear potenCaCon of the eyeblink startle reflex and subjecCve fear raCngs. ParCcipants were genotyped for geneCc polymorphisms located within cannabinoid receptor 1 (CNR1).Results: As predicted from the preclinical literature, acquisiCon and expression of condiConed fear did not depend on innate variability in CNR1. However, geneCc variability within CNR1 was associated with exCncCon of fear-‐potenCated startle. Crucially, CNR1-‐dependent resistance to exCnguish fear was accompanied with higher levels of fear-‐potenCated startle at the end of the exCncCon training.Discussion: These results show for the first Cme involvement of the human endocannabinoid system in fear exCncCon. ImplicaCons are that geneCc variability in this system may underlie individual differences in anxiety, rendering cannabinoid receptor 1 a potenCal target for novel pharmacological treatments of anxiety disorders.

11.20 – 11.40 Dennis Hofman – Fairness modulates non-‐conscious facial mimicry in women

In socieCes with high cooperaCon demands, implicit consensus on social norms enables successful human coexistence. Mimicking other people’s acCons and emoCons has been proposed a means to synchronize behaviour, thereby enhancing affiliaCon. Mimicry has long been thought to be reflexive, but it has recently been suggested that mimicry might also be moCvaConally driven. Here, we show during an economic bargaining game that automaCc happy mimicry of those making unfair offers disappears. Aeer the bargaining game, when the proposers have acquired either a fair or unfair reputaCon, we observe increased angry mimicry of proposers with an unfair reputaCon and decreased angry mimicry of fair proposers. These findings provide direct empirical evidence that non-‐conscious mimicry is modulated by fairness. We interpret the present results as to reflect that facial mimicry in women funcCons condiConally, dependent on situaConal demands.

11.40 – 12.00 Estrella Montoya – Moral reasoning is influenced by testosterone administraCon depending on second-‐to-‐fourth digit raCo

Recent research in the field of social neuroscience points at a role for hormones in our moral judgments. For example, administraCon of the pepCde oxytocin is found to influence the decision to sacrifice someone in order to save a larger collecCve [1]. The steroid hormone modulates neural and autonomic responding towards emoConal sCmuli and importantly the hormone influences


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social decision-‐making [2,3]. The present study therefore invesCgates whether testosterone is causally involved in moral decision-‐making and tested healthy females using testosterone administraCon and high-‐emoConal moral dilemma scripts [4]. Because testosterone administraCon effects may depend on fetal hormonal priming [5], we also took the proxy for fetal exposure to the hormones testosterone and estradiol, the right-‐hand’s second-‐to-‐fourth digit raCo (2D:4D) [6] into account. Results indicate that testosterone is involved in moral reasoning, depending on 2D:4D, in that subjects with relaCve low and relaCve high fetal testosterone priming show different effects of testosterone administraCon. These findings are in line with our earlier findings which show that fetal testosterone on basis of 2D:4D modulates acute effects of the very hormone in later life [5]. [1] De Dreu et al., 2011 , [2] Bos et al., 2011, [3] Eisenegger et al., 2011, [4] Greene et al., 2004, [5] van Honk et al., 2011, [6] Zheng & Cohn, 2011


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Abstracts Poster SessionMarCjn Barendregt -‐ Speed-‐dependent stereomoCon scotoma

The ability to perceive moCon in depth is vital for survival. Surprisingly, a large percentage of the populaCon has areas in the visual field that are less or not at all sensiCve to stereomoCon, called stereomoCon scotomas [Hong & Regan, 1989, Vision Research, 29(7), 809-‐819]. We hypothesized that these scotomas are specific to one parCcular cue for stereomoCon: changing disparity over Cme. To test this we measured stereomoCon fields in 6 subjects using a sCmulus with two different monocular speeds. It is known that the two stereomoCon cues have different speed tuning profiles [Czuba et al., 2010, Journal of Neurophysiology, 104, 2886-‐2899] and thus might be separated based on sCmulus speed. In all subjects we found stereomoCon fields that were stable over Cme within each speed condiCon. Overall subjects showed weaker sensiCvity to stereomoCon in the speed condiCon opCmized for the changing disparity cue. These stereomoCon scotoma were not explained by the fall-‐off with eccentricity that is expected for the disparity-‐based cue and extended to the lowest eccentriciCes we measured. Our results suggest that the moCon-‐based cue for stereomoCon might be more consistent across the visual field than the disparity-‐based cue. Furthermore, our results show that the stereomoCon scotoma idenCfied by earlier studies are not a general stereomoCon phenomenon, but specific to the disparity-‐based cue.

Anouk de Brouwer -‐ The effect of the Müller-‐Lyer illusion on reflexive, delayed, and memory-‐guided saccades

The amplitude of saccadic eye movements is affected by size illusions such as the Müller-‐Lyer illusion. The magnitude of the effect of the Müller-‐Lyer illusion on saccades shows a large variability over different studies (2.5-‐28.7%; Bruno, Knox, De Grave, 2010). Our goal is to further clarify this variability by tesCng the influence of a delay on the effect of the Müller-‐Lyer illusion. According to the “two visual systems hypothesis” (Milner & Goodale, 1995), responses to memorized target posiCons rely on a perceptual representaCon coming from the ventral ‘percepCon’ pathway, which is affected by visual illusions. The dorsal ‘acCon’ pathway, however, does not have access to this perceptual representaCon. The disCncCon between percepCon and acCon implies that reflexive acCons, dependent on the dorsal stream, are not (or hardly) affected by visual illusions, whereas memory guided responses are. In the present study, subjects performed two reflexive saccade tasks and two delayed saccade tasks with the Müller-‐Lyer illusion. Reflexive saccades were performed with and without a 200 ms gap before presentaCon of the illusion. The delayed saccade task included a delay during which the illusion (delayed response) or only the fixaCon dot (memory-‐guided response) was present. Contrary to the predicCons of the two visual systems hypothesis, the effect of the illusion was not the smallest for reflexive responses.

Alyanne de Haan -‐ The effect of visual threat on visuotacCle cueing in and outside of peripersonal space

The peripersonal space (e.g. the space directly around your body) is strongly related to visuotacCle integraCon. Possibly, this mulCmodal integraCon of informaCon allows you to make a predicCon of impending tacCle input based on visual informaCon. This could play an important role selecCng the appropriate response to the visual sCmulus. Indeed, previous studies in crossmodal afenConal cueing have shown that processing �

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Proceedings+of+the+6 HelmholtzRetreat · 2015. 12. 1. · Scienﬁcdirector Prof.+Dr.+F.A.J.+Verstraten+ UtrechtUniversity Membersof(the(board(of(the(Helmholtz(Research(School Prof.+Dr.+J.J.+Bolhuis+