The long term objective of the proposed research is to understand how cortical neurons integrate sensory inputs in space and time and hence contribute to sensory perception. The goal of the present application is to elucidate the substrates and mechanisms of rapid, context‑dependent response modulation (""""""""dynamics"""""""") in adult rat primary sornatosensory (SI) cortex. We propose to use whole cell recording of intracellular currents in vivo, simultaneous single unit recording from multiple neurons, and optical imaging of intrinsic signals from an expanse of cortex, to characterize the detailed electrophysiological changes that occur in individual SI neurons and in the SI map during stimulation of single whiskers and multiple whiskers. We propose the following specific aims: (1) Examine the spatial spread and temporal pattern of subthreshold input to SI neurons. The sum of the excitatory and inhibitory inputs to a neuron, its subthreshold receptive field, provides the spatial substrate for dynamic integration. We shall use intracellular recording to describe the extent of subthreshold receptive fields as well as the temporal characteristics of single‑whisker responses that are critical for multi-whisker interactions. (2) Exornine cortical integration during temporal modulation -of single whiskers. We have recently used optical imaging techniques to demonstrate a sharpening of the spread of cortical activity with increasing frequency of whisker stimulation. To explicate the changes underlying this paradigmatic case of dynamic integration, we shall record intraceBu1arly from SI neurons during stimulation of individual center and surround whiskers at increasing frequency. (3) Examine cortical integration during multi‑whisker stimulation, particularly as amplitude, frequency and direction of motion of central and surround inputs is varied. We shall carry out parametric studies of multi‑whisker responses, as well as examine specific hypotheses derived from a model of cortical dynamics postulating how interactions between center and surround whiskers sharpen the representation of salient inputs in cortex. Information from these experiments will be important for understanding the integration of multiple inputs in sensory cortex, and more generally for understanding cortical mechanisrns of object detection and discrimination.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS039022-04
Application #
6639588
Study Section
Special Emphasis Panel (ZRG1-IFCN-4 (01))
Program Officer
Babcock, Debra J
Project Start
2000-04-07
Project End
2005-03-31
Budget Start
2003-04-01
Budget End
2004-03-31
Support Year
4
Fiscal Year
2003
Total Cost
$245,480
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Other Basic Sciences
Type
Other Domestic Higher Education
DUNS #
001425594
City
Cambridge
State
MA
Country
United States
Zip Code
02139