CPS Seminar Speaker Edward Callaway SEA 4.244

Contact Name: 
Jenna Whitney
Date: 
Dec 4, 2006 12:00pm - 1:00pm

Speaker/Affiliation: Edward M. Callaway Ph.D. As

sociate Professor Salk Institute for Biological Studies Systems Neurobiol

ogy Laboratories

When/Location: 12/4/2006 12:00 PM SEA 4.244
Title of Talk: Cell-Type and Fine-Scale Specificity of Cortical Circuits<

br>
Reception with Refreshments at 11:30 AM

Abstract: We have stu

died primary visual cortex to better understand how neural circuits give ri

se to perception. We have found that cortical circuits are extremely precis

e such that different neuron types and even neighboring neurons of the sa

me type are connected differently. For example different types of inhibit

ory neurons with overlapping dendritic arbors receive connections from diff

erent cortical layers. And neighboring excitatory neurons only receive comm

on input from the same presynaptic neurons in the minority of cases when th

ey are directly connected to each other. This fine-scale and cell type-spec

ific organization implies that studies of relationships between circuits an

d function should match this level of organization. To test hypotheses abou

t contributions of specific cell types to neuronal responses and to percept

ion we have developed methods to allow reversible inactivation of selected
cell types. We find that expression of an insect neuropeptide receptor whi

ch couples to GIRK channels can be used to selectively quickly and revers

ibly eliminate the activity of neurons in vivo. This methods allows tests o

f the role of particular cell types within the intact functioning neural n

etwork. To allow the circuitry of specific neurons to be more directly link

ed to function we have developed a method that allows the neurons directly

presynaptic to a single neuron to be labeled genetically. This method is co

mpatible with functional characterization of the postsynaptic neuron and fu

ture development should also allow functional characterization of the presy

naptic cells by expression of genetically encoded activity sensors.