Hmb300 h1f 2013final lecture

HMB300H1 - Dr. JU - Bye Class! 1

Try not to be afraid of CREBThe CREB and flow of memory

Season and Series Finale

HMB300 - Neuroscience


It’s something to be afraid of

• As we last left off in the world of neuroscience• CREB – another synaptic tag?• Molecules, transport and cargo• Fear memory – similar to other forms of memory• Altering fear memory – cool story bro’ but you have

to pay attention



Be afraid, very, very afraid

• Electrical stimulation of the amygdala in humans elicits fear and anxiety (Gloor et al., 1981)• Reward system from dopaminergic fibres that project from amygdala to the hippocampus? (Blum et al., 1996)• Panic attacks and aggression? Herman et al., 1992 reported that ictal fear predominant in amygdala- shows prominent EEG activity•Classic paper by Mesulam 1981 shows abnormal EEG activity with panic attacks, fear and paranormal delusions in amygdala



So what is next?

• Can we merge what we know about memory, different areas of the brain and behavioural tests

PKMzeta?

Local tag? Arc?



Understanding memory (again)

• One of the major tenets of memory theory, any type of memory is that groups of neurons have to be involved (a memory trace)

• These neuron ensembles (groups) are very sparse however – so it makes the detection of a memory trace very challenging

• Good correlation between certain neurons and memory encoding or expression but no definitive or direct proof



Technical challenges part II

• Must find a discrete area that is easily targeted that has been associated with a memory

• Must be able to selectively eliminate these neurons and not others

• Must also show directly, that by eliminating these neurons, you have selectively ablated those memories

• Optogenetics is one approach but this is yet another very useful technique


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Back to the old model - context

HMB300H1 - Dr. JU - Bye Class!



A new molecule in our repertoire

• Previous work had established that a group of neurons within the lateral amygdala (LA) increased levels of CREB following auditory fear training• Have neurons in this area overexpressing CREB (both active and dominant negative as control)• Ones expressing CREB much more likely to be activated during a contextual fear training model• So within this area, can we lesion these CREB overexpressing neurons?



CREB a central player

• Know certain things about fear memory in the lateral amygdala

• It is protein synthesis dependent – cycloheximide and actinomycin D

• It requires GluA1 – also known as GluR1

• Other downstream molecules seem to be very important – BDNF, Arc/Arg3.1, cytoskeletal proteins, IEGs zif268,Homer1a and PKMz



Just a quick review of molecules

AD• Activated synapses increase signaling of CaMKII etc. that lead to activation of MAPK (mitogen activated protein kinase) – among others...

• MAPK can translocate to the nucleus to cause the increased phosphorylation of CREB

• phosphoCREB is the activated transcription factor that binds to nuclear DNA sequences that contain cyclic AMP response elements (CRE)

• Also binds to CREB Binding Protein (CBP) which acts to enhance activity to cause transcription of factors such as c-fos, zif268, BDNF, etc.



Let’s take stock for a moment

• Use a contextual fear response to evoke a fear memory

• Neurons that are involved in LTP-like responses are express more CREB

• Have a unique mouse that expresses iDTR in every cell in every part of the body including the amygdala (DTR is not normally found in mice)

• Create a specific vector that incorporates both things CREB-Cre and put it into a viral vector that infects specific neurons



Amazing specificity

• Mice must be made to express DT Receptor• Stereotactically nject a vector that targets LA

neurons, and activates the DT Receptor but only in ones that are made to express CREB

• Inject DT and the toxin works into the area and destroy selective neurons by apoptosis

intraperitoneal



Memory consolidation molecules?

AD

loxP loxP

Inject only in lateral amygdala

All cells have inactive Rosa All cells have inactive Rosa All cells have inactive Rosa



Sometimes napping does help

Specific effect, since random ablation of small number of inactive neurons (i.e. those without high levels of CREB)didn’t erase the fear memory


Talk promotors here

CaMKIISynapsin IGFAPGAD65


Incredible effect

• Rosa mouse allows specific ablation of neurons that overexpress CREB that has become associated with a learned fear response

• Effects were specific and offer a different route for being able to manipulate discrete group of neurons – in this case ablation of neurons associated with a memory

• Still cited as a classic paper and variations are still being published today



For your information (FYI only)

• If you want to learn more on this technique and some of the challenges associated with it check out the following paper

• Han J-H, Kushner SA, Yiu AP, Cole CA, Matynia A, Brown RA, Neve RL, Guzowski JF, Silva AJ, Josselyn SA. (2007) Neuronal competition and selection during memory formation. Science 316:457-460.

• Han J-H, Kushner SA, Hsiang HL, Yiu AP, Buch T, Waisman A, Bontempi B, Neve RL, Frankland PW, Josselyn SA. (2009) Selective erasure of a fear memory. Science 323:1492-1496



Almost The End

Why do my Profs suck at teaching?

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What do you think?


This family is:A) SadB) AngryC) HappyD) Calm

I agreeA) YesB) No


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Can you pick up on his vibe?


This man is:A) SadB) AngryC) HappyD) Calm

I agreeA) YesB) No


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How did you come to understand the context?

• Different theories to try and understand what happens when you observe things in others

• You have basically taken on the perspective of someone else

• How did this occur? How did you understand the other person’s perspective?

• Intuitive learning model• Theory of Mind model

The beginnings of a theory



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Great theory but controversial


• How do we understand what is going on?• How do we process what we perceive?• Is this a simple model such as sensory

perception (what we see), cognition (processing) and then turn this into action?

• In many ways this process resembles what is known as the Theory of Mind


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Does your Prof understand?


• Theory of Mind allows an individual to understand the mental states and belief systems of others (that may be different from their own)

• Very closely associated with empathy• This may be what allows us to understand those

pictures without any other clues or guidance• Our ability to understand or take on the

viewpoint of others may allow us to imitate them better


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Profs unlearn this ability?


• Are we born with this ability to understand others?

• Do we have the innate ability to understand the intention of others?

• Most researchers believe that we have to develop or learn a theory of mind

• It turns out that children are incapable of truly understanding others until they reach a critical age


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Beginning of a new theory


• Famous research on what is known as the false-belief system (other individuals may have an inappropriate understanding) Wimmer, H., & Perner, J. (1983) Beliefs about beliefs: Representation and constraining function of wrong beliefs in young children's understanding of deception. Cognition, 13, 103-128


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A simple test


• One of the tests originally used to understand false beliefs in the theory of mind was known as the Sally-Anne task

• There are 2 containers, 2 characters and children are asked whether one character will have a false belief or not

• Can the child predict behaviour correctly?


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Playing with dolls


• Children over a certain age pass

• Children with developmental problems fail (such as Autism or Asperger’s Syndrome)

http://www.youtube.com/watch?v=57bYqiRYxyg


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How do we account for this?


• One of our central tenets in this course is that behaviour can be explained by examining the brain

• How can we account for our ability to understand others, and to show empathy?

• There must be a structure or structures in the brain that accounts for this

• 1970s through to the 1990s


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Great mistakes – great findings


• Italian neuroscientists Giacomo Rizzolatti, Vittorio Gallese, Leonardo Fogassi and colleagues studying brain and motor activity

• Using electrodes, measured activity of single neurons in macaque brains in the premotor cortex

• In monkeys, this area had been shown to be active during the times where monkey grasps or manipulates objects

• i.e. neurons are active when monkey picks up a peanut or cracks the shell


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Strange results


• Activity within the monkey premotor cortex triggers movements

• In humans, stimulation of premotor cortex results in patients reporting urge to perform actions

• In other words, it is part of our ability to trigger voluntary movement

• Key finding came while recording in monkey brain, that when the experimenter picked up the peanut that the same neuron fired

• Why should this neuron fire? • It shouldn’t!


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If you see it, you feel it


• Very specific activation patterns

• Not food alone• Not hand alone• Need to be

performing same task and see the same task being performed

• Gallese V, Fadiga L, Fogassi L, Rizzolatti G. 1996. Action recognition in the premotor cortex. Brain 119:593-609


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Mirror neurons – so cool!


• As the activity that was elicited was so specific, it was hypothesized to be an actual finding

• Interestingly, only specific to a point• Later it was determined that these types of neurons –

now known as mirror neurons – were activated by sound as well (Christian Keysers)

• The experimenters proposed that these specific cells within the monkey’s brain could transform what they were seeing into motor programs


Is your whole brain full of these?


• Originally these mirror neurons that are activated by the actions of others were found in the area F5 (the ventral premotor cortex)

• Later also found in the inferior parietal lobe

Superior temporal sulcusBiological motionperception

RIPL (multimodalsensory processing)

What percent?

Estimated around 10%


Actions speak louder than words


• Originally thought to be important for action understanding

• In other words, these mirror neurons allow us to truly understand actions that we couldn’t understand just by seeing them alone (i.e. holding that cup of coffee – beyond just seeing cup and a hand)

• As part of this, these neurons are also likely important for imitation and imitation learning (big proponent being the Iacoboni group


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We’re better than supercomputers


• Beyond merely associating and understanding motor activities well these mirror neurons have also been proposed to be involved in intention understanding

Iacoboni M., Molnar-Szakacs I., Gallese V., Buccino G., Mazziotta J.C., Rizzolatti G. 2005 Grasping the intentions of others with one's own mirror neuron system. PLoS biology, 3, e79


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Even more complex actions?


• Watch someone cut their finger? Your response?• Are mirror neurons responsible for empathy?• There is a parieto-premotor circuit that seems to

be activated in response to emotions• Exposure to disgusting odours activates the

insula and the anterior cingulate cortex• Interestingly watching people who showed

disgust also activated the insula• Wicker B., Keysers C, Plailly J, Royet JP, Gallese V, Rizzolatti G.. (2003) Both

of us disgusted in my insula: The common neural basis of seeing and feeling disgust. Neuron 40, 655-664.


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I was once a groupie


• Meeting up with a Rock Star

• V.S. Ramachandaran• Single-handedly proposed

that these neurons are the coolest things of all time

• Called them the most important discovery of the last decade

• "mirror neurons will do for psychology what DNA did for biology".

http://www.ted.com/talks/vs_ramachandran_the_neurons_that_shaped_civilization.html


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But can they slice and dice?


• Mirror neurons have been proposed to be what allowed humans to develop language (originally proposed back in 1998)

• Morality? If I can feel your pain, if I can see your point of view – it would mean that I would have to change my value systems

• Still a matter of great debate


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The search for UFOs in the brain


• The big question – not sure• Likely yes, but no one has yet recorded

electrically from neurons in the proposed areas of the HUMAN brain

• All of the studies to date have been using EEG, MEG and fMRI

• Lingnau, Angelika; Gesierich, Benno; Caramazza, Alfonso (2009), "Asymmetric fMRI adaptation reveals no evidence for mirror neurons in humans", PNAS 106 (24): 9925–9930,


http://en.wikipedia.org/wiki/Proceedings_of_the_National_Academy_of_Sciences

And they lived happily ever after

• Until this year down in UCLA• Mukamel et al. Single-Neuron Responses in

Humans during Execution and Observation of Actions. Current Biology, 2010

• 1177 cells in 21 patients human medial frontal and temporal cortices (seizure patients)

• patients executed or observed hand grasping actions and facial emotional expressions





Left

SM

AM

edial temporal lobe

right entorhinal cortex



• Cells in SMA respond during execution and observation of actions

• Cells in medial temporal lobe respond during observation and execution of actions

• Some respond with excitation during execution and inhibition during observation

• Did not find evidence of such cells in the ACC, amygdala or in the pre-SMA

• Did not record from F5 but SMA (lateral vs medial)



Review of autism


• Developmental issues within brain• Typical symptoms occur by the age of 2-3 years• Poor social interactions• Lack of communication/speech difficulties• Repetitive almost obsessive behaviour• Often exhibit echolalia• Deficits in motor skills also tightly linked• Genetic causes not fully established


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Super controversial


• In autism, there are very poor social skills, and an inability to imitate and understand the intent of others

• Could this be due to problems with mirror neurons• Anatomic evidence showing that the areas where

mirror neurons are supposed to be localized are thinner or smaller in autistic patients

• fMRI studies suggest that these areas are also less active during imitation in autistic children


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HMB300H1S:Keep Calm – It’sThe END

Dr. Bill Ju105C Wetmore [email protected]@gmail.com


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Useful or useless?



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This was all that I knew



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Nowadays


Spinning disc lasers


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Even more mind-blowing



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I feel like I’m living in a Sci-Fi story


THG microscopy


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In living animals



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New developments all the time



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What my students picked


• Stem cell therapy• Brain machine interfaces• Imaging studies (human and research)• Machine and artificial intelligence• Beyond fMRI• RNAi technology• Nanotechnology including brain nanotechnology


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And now for the Glogster Awards


• Thanks for your continued excellence• Amazing material – best I’ve seen and amazing!• Very creative and I’m glad I didn’t have to

choose• All of you did so well but your peers have

nominated:• Then off to Project Impact


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Content Comprehensiveness



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Visual Appeal



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Best Linked



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Student’s Choice



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Most Nominated (Other)



• Alison Boven• Shana Kim• Bahar Amani• Xiao Yu• Arya Abdool• Cynthia Xu

Project Impact


Goals of Project Impact

• Help form the next generation of leaders, professionals and professors

• Help change the program and the University of Toronto

• Originally 5 -10 year plan (last year)• Both small scale and large scale changes• Personal investment on both parts (yours

and mine)


Goals of Project Impact


Practical Goals for myself

• How to study or write assignments• Mentoring (a lost art)• Writing letters of reference or introducing

you to other professors• Helping with other aspects of your

University life?


Practical Advice for you

• Find good professors (yes, they exist)• “Stalk” good professors (build relationships)

but outside of HMB too!• Find courses that will help you finish your

degree but also fulfill you• Start planning early for post-graduate

studies (deadlines and requirements)• Specialize or not?


What courses should I take?

• First, fulfill your degree requirements• Know your strengths and weaknesses• Consider a research project course ONLY if

you can really invest the time (choices?)• Get help – 4th year courses have many of

the same types of assignments• Get into smaller courses as soon as

possible and you’ll love 4th year


What courses should I take?

• My wish list of courses:• PSY490s• NFS489 – Pretty decent but lots of writing• CBS430 & CSB432 – Love!• PSLs – many to Love! PSL440; PSL444• PCL475 – Love!• HMBs take 1 but with that come caveats• Research courses – LOTS ANA; CSB; PSL;

PSY; NEW; TRIN404; and yes even HMB


I need your help!

• Create a culture of change (it takes time)• Help me to make changes• Try hard and learn to budget time in your 3rd

and 4th years• Let me help if I can and then help me later

on (I think we can make good changes!)


Your final exam• 20 MCQs – more on this online • 4 SA (with parts – longer – the current online

assignment)• 2 hours long – you will need the time• Tutorial scheduled for 11th and 12th • Sample questions will be posted Dec. 9th



Technology

Hmb300 h1f 2013final lecture