LeechSwimCPG

This system stimulates the leech’s muscles so that the leech undulates (and swims). The activations of individual motor neurons oscillate in a coordinated fashion. The system does not require sensory feedback to produce this behavior; if you isloate the
leech’s nervous system and directly stimulate a cell that “turns on” the swim CPG, the activations of the motor neurons oscillate.

Each ganglion has its own little CPG that will oscillate on its own, but they are all linked together and in vivo the different ganglion’s CPGs will oscillate with set phase delays.

Here’s the known cells in the ganglion swim CPG, from (Brodfuehrer et al, 1995):

Note that these are known connections; there may be others.

here’s a site discussing this:

http://soma.npa.uiuc.edu/courses/physl490b/models/leech_swimming/leech_swim.html

References

these are kinda old:

• P.D. Brodfuehrer, E.A. Debski, B.A. O’Gara, W.O. Friesen, Neuronal control of leech swimming, J. Neurobiol. 27 (3) (1995) 403}418.
• W.O. Friesen, Neuronal control of leech swimming movements: interactions between cell 60 and previously described oscillator neurons, J. Comp. Physiol. A 156 (1985) 231}242.
• W.O. Friesen, Neuronal control of leech swimming movements I, inhibitory interactions between motor neurons, J. Comp. Physiol. A 166 (1989) 195}203.
• W.O. Friesen, Neuronal control of leech swimming movements II, motor neuron feedback to oscillator cells 115 and 28, J. Comp. Physiol. A 166 (1989) 205}215.
• W.O. Friesen, Reciprocal inhibition: a mechanism underlying oscillatory animal movements, Neurosci. Biobehav. Rev. 18 (4) (1994) 547}553.
• W.O. Friesen, M. Poon, G.S. Stent, Neuronal control of swimming in the medicinal leech IV, identi"cation of a network of oscillatory interneurones, J. Exp. Biol. 75 (14) (1978) 25}43. [7] W.O. Friesen, G.S. Stent, Generation of a locomotory rhythm by a neural network with reccurrent cyclic inhibition, Biol. Cybernet. 28 (1) (1977) 27}40.
• W.O. Friesen, Neuronal control of leech swimming movements, in: J.W. Jacklet (Ed.), Neuronal and Cellular Oscillators, Marcel Dekker, New York, 1989.
• B. Granzow, W.O. Friesen, W.B. Kristan Jr., Physiological and morphological analysis of synaptic transmission between leech motor neurons, J. Neurosci. 5 (8) (1985) 2035}2050. [10] W.B. Kristan Jr., R.L. Calabrese, Rhythmic swimming activity in neurones of the isolated nerve cord of the leech, J. Exp. Biol. 65 (3) (1976) 643}668.
• C.A. Ort, W.B. Kristan Jr., G.S. Stent, Neuronal control of swimming in the medicinal leech II, identi"cation and connections of motor neurons, J. Comp. Physiol. 94 (1974) 121}154.
• R.A. Pearce, W.O. Friesen, A model for intersegmental coordination in the leech nerve cord, Biol. Cybernet. 58 (5) (1988) 301}311.
• J. Weeks, Synaptic basis of swim initiation in the leech II, a pattern-generating neuron (cell 208) which mediates motor e!ects of swim-initiating neurons, J Comp. Physiol. 148 (1982) 265}279.
• J.C. Weeks, Neuronal basis of leech swimming: separation of swim initiation, pattern generation, and intersegmental coordination by selective lesions, J. Neurophysiol. 45 (4) (1981) 698}723.
• Taylor A, Cottrell GW, Kristan WB Jr (2000). A model of the leech segmental swim central pattern generator. Neurocomputing 32-33: 573-584. (Also published in Computational Neuroscience: Trends in Research 2000, Bower JM, ed. Elsevier, Amsterdam.) (the other refs above were taken from here)

CategoryAnatomical

CategoryLeech