E. Paxon Frady: Swim Oscillator Neuron Review

Collecting papers on identified neurons from previous work.

Briggman, K.L., Kristan Jr., W.B. (2006) Imaging Dedicated and Multifunctional Neural Circuits Generating Distinct Behaviors. J. Neurosci 26(42):10925-10933.

This is a nice one of CV. You can see it is slightly lagging the DP oscillation, but I'm not entirely sure that the ganglion is 12. My guess is its 10 and he's recording DP 12, so the DP spikes are a little further behind.

And then he gets some nice simultaneous 208 and 255 recordings. Again this matches really nicely with my data as you can see 255 slightly leading 208. This is reflected in that 255 is in the red phase and 208 is in the purple phase in my data.

And he also recorded from 3 and 4, but these are on the dorsal face.

Weeks, J.C., Kristan Jr., W.B. (1978) Initiation, maintenance and modulation of swimmming in the medicinal leech by the activity of a single neurone. J. exp. Biol. 77: 71-88.

Here's the position of 204, which matches nicely

Depolarizing cell 204 leads to the initiation of the swim oscillation.

And then here is 204 during swimming

Ok, so I put 204 in the yellow phase, which I think this matches nicely. It is hard to tell because this is DP 12, but you can see how much the phases shift by comparing 204 (10) with 204 (11). The way I have it, 204 is in the yellow phase, which means its depolarization should slightly lead the DP nerve. It would be unclear, because the duty cycle of 204 is pretty long, which can maybe slightly alter the phase, but I'm fairly happy with it.

Weeks, J.C. (1982) Segmental specialization of a leech swim-initiating interneuron, cell 205. J. Neurosci. 2(7): 972-985.

Another paper from weeks looking at cell 205, which I don't see how to possibly differentiate from cell 204.

Although, wow it looks like S has a swim oscillation. She is showing that S is connected to cell 205, as well as cell 205 getting a bunch of input from sensory neurons -- sounds like its part of preparatory network.

But here is a simultaneous 204, 205 recording:

So, these are very similar. Maybe 205 is 263/264?

205 is the only one missing from my data set, but this is only in segment 9 according to Weeks, 1982.

"Unlike other swim neurons which are segmentally repeated, cell 205 generally is present only in segment 9, and numerous lines of evidence suggest that it is, in fact, a segmentally differentiated homolog of cell 204."

Friesen, W.O., Hocker, C.G. (2001) Functional Analyses of the Leech Swim Oscillator. J. Neurophysiol. 86:824-835.

This schematic is in a lot of Friesen's papers. I think most of the neurons involved in swimming that Friesen studies, however, are on the dorsal face.

And here's an intracellular of DI-1 during swimming:

Cang, J., Friesen, W.O. (2002) Model for Intersegmental Coordination of Leech Swimming: Central and Sensory Mechanisms. J. Neurophysiol. 87:2760-2769.

Another one of these phase diagrams from Friesen:

The rest of this paper is about modeling the swim behavior.

Brodfuehrer, P.D., Thorogood, M.S.E. (2001) Identified neurons and leech swimming behavior. Progress in Neurobiology 63: 371-381.

Here is a diagram of the cascade that causes swimming and a recording of DE3

More circuits and recordings. The legend says panel A is from Friesen 1989, and panel B is from Nusbaum 1987, which I need to find.

Not sure what SIN1 is, this is from Brodfuerher and Burns 1995:

Taylor, A.L., Cottrel, G.W., Kleinfeld, D., Kristan Jr., W.B. (2003) Imaging Reveals Synaptic Targets of a Swim-Terminating Neuron in the Leech CNS. J. Neurosci. 23(36):11402-11410.

Here they use the VSDs to find cells that are targeted by Tr2, which is a head cell that terminates swimming. He identifies two cells - 256 and 252 that are targeted by Tr2. These cells seem to also terminate swimming, but not really clear if they are oscillators.

Here are ephys recordings, but it doesnt seem that 256/252 are oscillators

Kristan Jr., W.B., Calabrese, R.L., Frieson, W.O. (2005) Neuronal control of leech behavior. Progress in Neurobiology 76: 279-327.

Pretty detailed review. Good source to cite as leech cells being homologous: "Most midbody ganglia have the same neurons and locations of the soma."

7. The nervous system is iterated, with homologous neurons found in most, if not all, 21 segmental ganglia (Fig. 1). So despite having more than 10,000 neurons, the functional unit (i.e. the number of different kinds of neurons) of the leech CNS is relatively small. For instance, there are only 400 neurons per segmental ganglion (Macagno, 1980), and most of these are paired. Thus, in essence, the segmental nerve cord (roughly corresponding to the spinal cord in vertebrates) consists of 42 copies (one on each side of 21 segments) of a basic unit of 200 neurons.

And another version of the circuitry figure, with colors!

Brodfuehrer, P.D., McCormick, K., Tapyrik, L., Albano, A.M., Graybeal, C. (2008) Activation of two forms of locomation by a previously identified trigger interneuron for swimming in the medicinal leech. Invert. Neurosci. 8:31-39.

Mostly about Tr1. But here's a CV:

And it looks like Retzius has a clear swim oscillation. Hard to tell its phase from this picture, however.

Friesen, W.O., Kristan, W.B. (2007) Leech locomotion: swimming, crawling, and decisions. Current Opinion in Neurobiology 17:704:711.

This paper just wanted for this figure to cite the "Do something!" network.

Friesen, W.O. (1989) Neuronal control of leech swimming movements I. Inhibitory interactions between motor neurons. J. Comp. Physiol. A. 166:195-203.

Ok this is Otto's original papers on swimming. The first one is about the motor neurons and their connections:

Here's the classic about the motor neuron coupling:

Friesen, W.O. (1989) Neuronal control of leech swimming movements II. Motor neuron feedback to oscillator cells 115 and 28. J. Comp. Physiol. A 166:205-215.

Yeah so most of the diagrams that I'm interested in originally come from this paper.

Nusbaum, M.P., Friesen, W.O., Kristan Jr., W.B., Pearce, R.A. (1987) Neural mechanisms generating the leech swimming rhythm: Swim-initator neurons excite the network of swim oscillator neurons. J. Comp. Physiol A. 161: 355-366.

This is a good set of ephys recordings. Except, here, 60 and 208 are opposite phases, which is not what I have them labelled as. This is the only 60 that I could find, but maybe this 60 is what I call 57 or 58.