Neuroscience 2005 Abstract
| Presentation Number: | 54.5 |
|---|---|
| Abstract Title: | The interaction between two synapses with distinct dynamics in a reciprocally inhibitory rhythmic network. |
| Authors: |
Zhou, L.*1
; LoMauro, R.1
; Zhao, S.1
; Nadim, F.1
1Biol. Sci., Rutgers Univ., Newark, NJ |
| Primary Theme and Topics |
Sensory and Motor Systems - Pattern Generation and Locomotion -- Invertebrate pattern generation |
| Secondary Theme and Topics | Neural Excitability, Synapses, and Glia: Cellular Mechanisms<br />- Network interactions<br />-- Oscillations and synchrony |
| Session: |
54. Invertebrate Pattern Generation I Poster |
| Presentation Time: | Saturday, November 12, 2005 1:00 PM-2:00 PM |
| Location: | Washington Convention Center - Hall A-C, Board # W19 |
| Keywords: | STOMATOGASTRIC, MODELING, CENTRAL PATTERN GENERATOR, OSCILLATION |
Reciprocal inhibition is a primary mechanism through which oscillations are generated in nervous systems. We study the contribution of synaptic dynamics to rhythm generation in reciprocally inhibitory networks of the crustacean pyloric CPG. The inhibitory synapse from the LP to the PD neurons is the sole chemical synaptic feedback to the pyloric pacemaker group of neurons (AB/PD). This synapse consists of two components: a spike-mediated and a non-spike-mediated (graded) component. In the ongoing pyloric rhythm, the spike-mediated component of this synapse is dominant. In contrast, the inhibitory synapse from AB/PD to LP is mainly graded. We propose that the distinct dynamics of these two synapses play an important role in controlling the pyloric rhythm. To examine this hypothesis, we used a synaptic release model based on experimental data from the LP to PD synapse (LoMauro et al, SFN abst 657.17, 2004). This model can accurately predict the postsynaptic response of PD neurons to any temporally patterned LP neuron activity. We incorporated this model into a simple network model consisting of a pacemaker (O) and a follower (F) neuron. The inhibitory synapse from O to F is graded, while the synapse from F to O is spike-mediated. The period of O was adjusted by injecting different amounts of external current. A longer period of O evoked a stronger graded synapse to F because the strength of the graded synapse depends on the time course of its recovery from depression and the amplitude of the presynaptic membrane voltage. The strong inhibitory synapse from O to F caused a strong rebound in F, which resulted in more F spikes/burst. This, in turn, produced a larger spike-mediated synapse from F to O. Thus, the period of this simple network is fine tuned depending on the spike frequency and number of spikes in F. These results show that the combination of these two different dynamic synapses can be effective in controlling the network rhythm and maintaining proper phase relationships.
Supported by NIH MH60605
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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