Signal Propagation in a Small Neural Network

24 downloads 0 Views 3MB Size Report
quiets chemical synapses, and Picrotoxin which inhibits glutamatergic synapses. Lucifer Yellow fills of the IC cell (blue) show extensive branching. The PD cell ...
ot ec te d.

Signal Propagation in a Small Neural Network:

Poster #: JJ17 585.11

op

0

ot

00

ht

F1 0

pr

er s. C op

yr ig

ec t

Po st

Brandeis University, Waltham, MA

ot ec te d.

yr ig

F

h

Po st 00 F1 0

ed .

Gabrielle Gutierrez, Marie Goeritz, and Eve Marder

ht yr ig

ht

pr

ot

er s. C op

yr ig

Po st

Po st

IC cell fills

er s. C op

0 00 F1 ed . ec t

00

The IC makes profuse aborizations in the neuropile of the STG and can be thought of as a “hub”. Current perturbations of the IC influence neurons in both the gastric and pyloric networks. At present, no clear frequency dependence is observed. When inhibitory synapses are reduced in strength, the current injections into IC do not propagate as effectively for higher frequency stimuli. This suggests distinct contributions from electrical and chemical synapses. We are now studying the effects of neuromodulators on signal propagation in the STG.

e

Po st

0

00

We would like to thank the Marder lab for their support and good humor. We would espeically like to thank Brian Slepian, Roger Yang, and Lansara Jaruthien our very talented undergrads.

F1

ec t ot pr ht

This research was made possible with funding from MH46742 and NS17813.

te ct ro

.C

op

yr

ed .

ig

st

Acknowledgemtns

ed .

F1

Conclusion

0

ot pr ht yr ig C op s.

er

Neuromodulator Experiment

Neuromodulators reconfigure neural circuits. Do they change the signal propagation properties of the STG?

Po 00 10

pr

Po st er s. C

0 00 ed . ec t ot pr

ht

yr ig .C op rs st e Po

10 00 .F te d ec ot pr

Network Coherence 1 Hz sine 0.7 Hz sine

.C op

rs st e Po 10 00 ht

The coherence between the recorded cells and the injected current is not significantly different across conditions, but there is a trend toward less coherence for the higher frequency injections in reduced calcium saline.

1 Hz sine

Electrophysiology Experiments

Lucifer Yellow fills of the IC cell (blue) show extensive branching. The PD cell (yellow) is filled with Neurobiotin (4%). The pink indicates Synorf (presynaptice marker) in the respective cell. This shows distributed chemical synapses between the IC and PD cell. Below is a Neurobiotin (4%) fill of IC. Surrounding the neuropile are dye-coupled cells indicating many electrically coupled partners.

0.3 Hz sine

ct ed .F

F1

0.3 Hz sine

pr yr ig

ht

st e

Po

We inject a sinusoidal current signal into the Inferior Cardiac (IC) cell in the STG and record the activity of many of the other STG cells extracellularly. We repeat these injections while perfusing reduced calcium saline, which quiets chemical synapses, and Picrotoxin which inhibits glutamatergic synapses.

0

Control

ot

We investigate these questions with a series of electrophysiology experiments in the crustacean stomatogastric ganglion (STG) which is a small neuronal network of about 25 cells.

Picrotoxin

Control

te

Reduced Ca2+

Saline

ed .

ec t

.C op

What role do inhibitory synapses and electrical couplings have in signal propagation?

rs

Introduction

yr ig

Do signals propagate differently through a neural network as a function of signal frequency?

F1

ht

pr

00

The contribution of inhibitory synapses and electrical gap junctions to signal propagation properties of a central pattern generator

Suggest Documents