Journal of neurophysiology
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1. The temporal and spectral characteristics of neural representations of a behaviorally important species-specific vocalization were studied in neuronal populations of the primary auditory cortex (A1) of barbiturate-anesthetized adult common marmosets (Callithrix jacchus), using both natural and synthetic vocalizations. The natural vocalizations used in electrophysiological experiments were recorded from the animals under study or from their conspecifics. ⋯ At the same time, the responses evoked by a vocalization scattered in discrete cortical patches were strongly synchronized to stimulus events and to each other. As a result, at any given time during the course of a vocalization, a coherent representation of the integrated spectrotemporal characteristics of a particular vocalization was present in a specific neuronal population. 7. These results suggest that the representation of behaviorally important and spectrotemporally complex species-specific vocalizations in A1 is 1) temporally integrated and 2) spectrally distributed in nature, and that the representation is carried by spatially dispersed and synchronized cortical cell assemblies that correspond to each individual's vocalizations in a specific and abstracted way.
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1. The cerebellar uvula-nodulus receives vestibular projections from primary and secondary vestibular afferents as well as vestibularly related climbing fibers. It also receives visually related information from climbing fiber pathways. ⋯ CFRs driven exclusively by horizontal, posterior-->anterior optokinetic stimulation of the ipsilateral eye were distributed in a sagittal strip approximately 0.5 mm wide located 0.5-1.0 mm from the midline and restricted to the ventral nodulus. CFRs driven by the ipsilateral anterior semicircular canal were found in a sagittal strip approximately 1.0 mm wide extending 1.0-2.0 mm from the midline. 6. The sagittal, topographically arrayed climbing fiber strips effectively map a mediolateral gradient of possible postural responses based on vestibular and optokinetic information.
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1. Motor and somatosensory cortex project massively to the primate striatal matrix, terminating in distributed sets of overlapping projection zones (matrisomes) within the putamen. To study this system quantitatively, we have developed a computer-assisted estimation of the changes in magnification that occur as motor and somatosensory cortical body representations are projected onto the putamen. 2. ⋯ Both had large representations of hand, foot, and mouth, and smaller representations of trunk. 5. The relative magnification of the motor cortex projection to the striatum was roughly twice as large as those of projections from individual somatosensory areas. 6. These findings suggest that, in the sensorimotor striatum, motor and somatosensory inputs may undergo different proportions of local processing at the borders of their distribution zones (striosomes and matrisomes).
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1. The recruitment of evoked fast inhibitory postsynaptic currents (IPSCs) and excitatory postsynaptic currents (EPSCs) was examined using whole cell voltage-clamp recordings from layer V pyramidal neurons in slices of rat somatosensory cortex. Synaptic currents were evoked with graded electrical stimulation to assess the relative activation of IPSCs and EPSCs. ⋯ Non-NMDA receptor blockade with CNQX prevented synaptic activation of action potentials in these cells, even during cotreatment with magnesium-free solution. 7. Together, these results suggest that recruitment of GABA(A) ergic IPSCs in neocortex is ultimately driven via glutamatergic afferents arriving at non-NMDA receptors on interneurons. Properties limiting fast inhibition would favor the propagation of enhanced excitatory activity through the neuronal network.