Fast inhibition in the cortex is gated primarily at GABAergic synapses formed by local interneurons onto postsynaptic targets. Although GABAergic inputs to the somata and axon initial segments of neocortical pyramidal neurons are associated with direct inhibition of action potential generation, the role of GABAergic inputs to distal dendritic segments, including spines, is less well characteriz...

The anterior forebrain pathway (AFP) of the oscine song system is essential for song learning but not song production. Most cells recorded in this serially connected pathway show increased firing in response to song playback, suggesting largely excitatory connections among AFP nuclei. However, the neurons forming a key projection in this pathway, from area X to the medial nucleus of the dorsola...

The postnatal ontogeny of [t25I]a-bungarotoxin (a-Btx) binding distribution in rat neocortex was described and quantified using autoradiography of in vitro labeled brain sections. During the first two weeks, distinctive transitory radial and laminar patterns emerged. Dense columnar bands of a-Btx binding extended through the depth of primary sensory cortex, including somatosensory, visual and a...

Neural networks of the rodent barrel cortex are particularly tractable for developing a quantitative understanding of response transformations in a cortical column. A column in barrel cortex consists of approximately 10 compartments. Two thalamic input pathways, a sensory lemniscal one and sensorimotor paralemniscal one, are transformed to approximately 7 population outputs, each with distinct ...

There is strong evidence that growth-associated protein (GAP-43), a protein found only in the nervous system, regulates the response of neurons to axonal guidance signals. However, its role in complex spatial patterning in cerebral cortex has not been explored. We show that mice lacking GAP-43 expression (-/-) fail to establish the ordered whisker representation (barrel array) normally found in...

Neurons in primary visual cortex exhibit several nonlinearities in their responses to visual stimuli, including response decrements to repeated stimuli, contrast-dependent phase advance, contrast saturation, and cross-orientation suppression. Thalamocortical synaptic depression has been implicated in these phenomena but has not been examined directly in visual cortex in vivo. We assessed depres...

Increasing evidence points to the importance of intrinsic molecular cues in specifying the regional identity of mammalian neocortex. Few such cues, however, have been found to be restricted to individual functionally defined cortical areas before the arrival of afferent information. In contrast, thalamocortical axons are specifically targeted to individual cortical areas, raising the possibilit...

Thalamocortical cells receive sensory signals via primary sensory afferents and cortical signals via corticothalamic afferents. These signals are influenced by a variety of neuromodulators that are released in the thalamus during specific behavioral states. Hence, different neuromodulators may set different thalamic modes of sensory information processing. We found that noradrenergic activation...

We have employed immunohistochemistry for multiple markers to investigate the structure and possible function of the different compartments of human cerebral wall from the formation of cortical plate at 8 postconceptional weeks (PCW) to the arrival of thalamocortical afferents at 17 PCW. New observations include the subplate emerging as a discrete differentiated layer by 10 PCW, characterized b...

1. The relation between the physiological pattern of ocular dominance and the anatomical distribution of geniculocortical afferents serving each eye was studied in layer IV of the primary visual cortex of normal and monocularly deprived cats. 2. One eye was injected with radioactive label. After allowing sufficient time for transeuronal transport, micro-electrode recordings were made, and the g...