Metabolic barrel representations with various patterns of neonatal whisker deafferentation in rats.

With various patterns of whisker deafferentation, C3 whisker stimulation produced divergently shaped metabolic barrel representations in layer IV of the primary somatosensory cortex. Whisker deafferentation results in functional and structural reorganization of the barrels in the primary somatosensory cortex. The present study examines the alteration of the metabolic barrel representations in layer IV with various configurations of selective whisker deafferentation in neonates, using [14C]2-deoxyglucose autoradiography. The deafferentation was produced by unilateral ablation of whiskers, leaving certain follicles intact. Configurations of intact follicles included: (I) row C follicles; (II) B3, C3, and D3 follicles; (III) B3, B4, C3, and C4 follicles; (IV) C2, C3, D2, and D3 follicles. The metabolic C3 barrel representations in layer IV after the deafferentations were found to have expanded only toward the barrel sites in which the corresponding whiskers were ablated, with no expansion toward the neighboring barrels. Expansion toward row D was significantly more pronounced than expansion toward row B, and expansion toward the C2 barrel was significantly more pronounced than expansion toward the C4 barrel. From these results, it can be inferred that asymmetric intrinsic structural connections are reflected in the functional metabolic barrel representation under the condition of neural plasticity in the barrel cortex following whisker deafferentation.