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|Paper IPM / Cognitive / 7843||
C-fiber depletion results in expansion of low threshold somatosensory mechanoreceptive fields. In this study, we investigated the role of intact C-fibers in GABAA mediated inhibition in barrel cortical neurons. We used electronically controlled mechanical stimulation of whiskers to quantitatively examine the responses of barrel cells to whisker displacements. After systemic injection of picrotoxin neuronal responses were recorded at 5 minute intervals for 20 minutes and then at 10 minute intervals for 100 minutes. Picrotoxin injection caused a 3 fold increase in response magnitude of adjacent whisker stimulation and 1.4 fold increase in response magnitude of principal whisker stimulation with a maximum enhancement 50 minutes after the injection. There was no significant change in spontaneous activity following picrotoxin injection. The response enhancement and receptive field expansion observed in normal rats were completely absent in the C-fiber depleted rats. These results suggest that the GABAA mediated inhibition that modulates the receptive field functional organization of the barrel cortex depends on intact C-fibers.
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