Neurons in somatic sensory cortex receive sensory information from the periphery throughout postnatal life. The central hypothesis for the proposed studies is that simple positive biases in the level of ongoing activity from selected whiskers is enough to potentiate their targeted synapses in cortex through glutamate receptor mechansisms. The studies will be carried out in the rat whisker to barrel field cortex pathway because the discrete, non-overlapping receptors in each whisker follide maintain a dear topography to and induding layer Iv of barrel field cortex. In addition, we have demonstrated that the receptive fields of neurons in adult rat barrel field cortex are modified by simply trimming some, but not all, of the whiskers for periods as short as 1 day or up to 30 days. Trimming all but two adjacent whiskers significantly increased the response of cortical neurons to spared whiskers and dramatically diminished the response to cut whiskers. The changes induced by whisker pairing were multifaceted and depend upon cell location in the barrel field cortex, the barrel's relationship to each whisker in the receptive field and how long they were trimmed or spared.
Four specific aims are identified to analyze the circuits and mechanisms that support these plastic responses in adult rat cortex:
Aim #1 is to compare the rate of change of synapses in each cortical layer induced by whisker pairing. Preliminary results show that supragranular neurons change before cells in any other layer. Two specific sub-goals are to test whether whisker pairing plasticity in the deeper layers requires prior changes in the superficial layers of cortex and whether the plasticity depends on glutamate receptor mechanisms.
Aim #2 is to compare the limits of response enhancement that can be generated in the VPM thalamocortical fiber synapses before and after whisker pairing.
Aim #3 is to analyze the role of extraIemniscal sensory modulators to barrel field cortex in the spread of activity between non-adjacent barrels when induced by whisker pairing. We will trim all but two non-adjacent whiskers to determine the effect of SII and POm lesions on the distance-limit for modifying connections between cortical barrels of the two intact whiskers.
Aim #4 is to show the effect of depletion of non-sensory neuromodulators in cortex on whisker pairing plasticity.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS025907-09
Application #
2037290
Study Section
Sensory Disorders and Language Study Section (CMS)
Program Officer
Baughman, Robert W
Project Start
1988-09-25
Project End
1998-11-30
Budget Start
1996-12-01
Budget End
1997-11-30
Support Year
9
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Other Health Professions
Type
Schools of Education
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
Ghoshal, Ayan; Pouget, Pierre; Popescu, Maria et al. (2009) Early bilateral sensory deprivation blocks the development of coincident discharge in rat barrel cortex. J Neurosci 29:2384-92
Sellien, Heike; Ebner, Ford F (2007) Rapid plasticity follows whisker pairing in barrel cortex of the awake rat. Exp Brain Res 177:1-14
Li, Lu; Ebner, Ford F (2007) Cortical modulation of spatial and angular tuning maps in the rat thalamus. J Neurosci 27:167-79
Rema, V; Armstrong-James, M; Jenkinson, N et al. (2006) Short exposure to an enriched environment accelerates plasticity in the barrel cortex of adult rats. Neuroscience 140:659-72
Schaffer, Chris B; Friedman, Beth; Nishimura, Nozomi et al. (2006) Two-photon imaging of cortical surface microvessels reveals a robust redistribution in blood flow after vascular occlusion. PLoS Biol 4:e22
Melzer, Peter; Champney, Gregory C; Maguire, Mark J et al. (2006) Rate code and temporal code for frequency of whisker stimulation in rat primary and secondary somatic sensory cortex. Exp Brain Res 172:370-86
Melzer, Peter; Sachdev, Robert N S; Jenkinson, Ned et al. (2006) Stimulus frequency processing in awake rat barrel cortex. J Neurosci 26:12198-205
Li, Lu; Ebner, Ford F (2006) Balancing bilateral sensory activity: callosal processing modulates sensory transmission through the contralateral thalamus by altering the response threshold. Exp Brain Res 172:397-415
Sellien, Heike; Eshenroder, Donna S; Ebner, Ford F (2005) Comparison of bilateral whisker movement in freely exploring and head-fixed adult rats. Somatosens Mot Res 22:97-114
Li, Lu; Rema, V; Ebner, Ford F (2005) Chronic suppression of activity in barrel field cortex downregulates sensory responses in contralateral barrel field cortex. J Neurophysiol 94:3342-56

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