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Comparison of central pattern generators and
locomotor movements
Péter HANTZEMBL Heidelberg, Arendt Laboratory
Lab Retreat Meeting, Weinheim, 19 october 2007
Swimming, flying, walking - stereotyped and rhythmicBreething, heartbeat - endogeneousStomatogastric movements - with modulation
}"Central pattern generators”
“Half-Centers Oscillator” for bursting
1 2
Leech heartbeat
video
Leech heartbeat
How is bursting maintained? -slowly-inactivating v.g. inward Ca2+ and/or Na+ currents
Why does the cycle alternate? -“escape” hyperpolarization activates inward v.g. Na+ and/or Ca2+ currents
-”release”activation of out- K+(Ca) or inactivation of in- Ca2+ currents
spike-frequency adaptation
Ion pumps!video
Medusae:the simplest animals with locomotor system
Hydromedusae two nerve rings
some have ocelli
Scyphomedusaenerve nets, rhophalia
Cubomedusaenerve net, one nerve ring,
camera-type rhophalia
Nerve rings
smooth radial muscles
striated circular muscles
Locomotion: - contraction of the circular muscles- shape recovery due to the bell elasticity
Hydrozoans
- pacemakers: subsystems of the inner nerve ring; unknown details
- NO increases swim frequency
Scyphozoans and Cubozoans
- the rhopalia act as pacemakers
- a set of pacemakers: faster and more regular swimming - ”resetting” (inhibitory?) interaction
Sarsia (Hydrozoan)
Figures: Mackie, Garm, Robson, Satterlie
Invertebrates: Swimming of Melibe and Tritonia
Melibe
- lateral flexions - doubled half-centers: L-R inhiibition - NO-erg: two bilaterally sym. cells - NO decreases swimming rate
MN MN
Diagram: Thompson et al.
Invertebrates: Swimming of Melibe and Tritonia
Tritonia:
- dorso-ventral flexions - magnetic sensing - C2 cell: dual junctions - VSI cells: delay mechanism
Diagram: Katz et al.
DSI
VSI
C2
DSI
VSI
C2
I
DSI
VSI
C2
E
DSI
VSI
C2
E
DSI
VSI
C2
DSI
VSI
C2
DSI
VSI
C2
df MN
vf MN
delay
Invertebrates: swimming of the medical leech
Pictures: Kristian, Friesen et al.
-dorso-ventral flexions
-bilaterally symmetrical hemisegmental circuits
-several unknown features
-no chance for simple qualitative picture
Vertebrates: swimming of the Xenopus embryo
com. IN
desc. IN
MN desc. IN
com. IN
MN
-experimental evidence for a basic circuitrylateral flexions, inhibitory L-R connections
-the CPG is distributed along the spinal cord
-NO selectively enhances Gly inhibition: frequency reduction
not clear: -oscillations occur in a half spinal cord: - wave propagation
recent models: crucial questions still unanswered
Model: Roberts
? ?
Vertebrates: swimming of the lamprey
By the way: Why segmental ganglions are necessary?
? ?
? ?
-experimental evidence for a basic circuitryLateral flexions, inhibitory L-R connections
-interneurons escape from inhibition- PIR
-partial blockade of Gly inhibition: frequency speed up
not clear: - oscillations occur in a half spinal cord: - intersegmental coordination:
?= just assumptions? ?
Figures: Grillner
Different frequencies
Different strengths and/ordifferent numbers of fibers
Differerent tartgets
Relative frequency Relative frequency
Intersegmental coordination: Coupled oscillators
Experimental support: same frequency, asymetric coupling
entrained frequency of an oscillator
phase of an oscillator
frequency of the uncoupled oscillator
rostal and caudal coupling functionsCR
k
k
k
H ,
)()( 11 kkCkkRkk HH The model:
"Phase-locked" solutions: traveling waves
Diagram: Williams
Platynereis dumerilii, Nereis virens:
Kinematics of the swimming was only investigated
Kondo
Applications
Robotics Recovery after Spinal Cord Injury
Scorpion
Attila and Hannibal
Salamandra Robotica
Nereis
Robot Lamprey
Progress Report
Immunohistochemistry:
•Attempt for classical staining with styril-based dyes, in cooperation with Young-Tae Chang, National University of Singapore
•In vivo methylene blue techniques (Smith, 1956)
•Successfull permeabilization by freezning
New Antibodies
•Choline Acetyltransferase
•Glutamic Acid Decarboxylase
•perhaps Nitric Oxide Synthase first: staining NADPH-diaphorase histochemistry
Exploring the Platynereis CPG
-Molecular fingerprint
-Multi-electrode recordings
-FRET
-Ion-sensitive dyes
-Dye filling
-Photochemical activation
-Developmental characterization
-Pharmacological assays
-Charactyerization of ion channels
coopertaions needed
Figs.:Kristian, Friesen
Acknowledgements
Arendt Group Detlev Arendt Foteini Christodoulou Alexandru Denes Antje Fischer Keren Guy Florian Raible Heidi Snyman Kristin Tessmar Raju Tomer Benjamin Backfisch Carmen Döring Nicola Kegel Katharina Willmann
Dirk BucherOtto FriesenAnders GarmBalázs GulyásAlan RobertsGáspár JékelyPaul S. KatzGyörgy KemenesWilliam KristianLajos LászlóGeorge MackiePéter SomogyiAndrew Spencer
Fellowship: Federation of European Biochemical Societies
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