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