Showing papers by "Kevan A. C. Martin published in 1989"
TL;DR: A simplified circuit of the visual cortex is developed that explains the intracellular responses to pulse stimulation in terms of the interactions between three basic populations of neurons, and reveals features of cortical processing that are important to computational theories of neocortex.
Abstract: We have used microanatomy derived from single neurons, and in vivo intracellular recordings to develop a simplified circuit of the visual cortex. The circuit explains the intracellular responses to pulse stimulation in terms of the interactions between three basic populations of neurons, and reveals the following features of cortical processing that are important to computational theories of neocortex. First, inhibition and excitation are not separable events. Activation of the cortex inevitably sets in motion a sequence of excitation and inhibition in every neuron. Second, the thalamic input does not provide the major excitation arriving at any neuron. Instead the intracortical excitatory connections provide most of the excitation. Third, the time evolution of excitation and inhibition is far longer than the synaptic delays of the circuits involved. This means that cortical processing cannot rely on precise timing between individual synaptic inputs.
483 citations
TL;DR: Recordings from a small neuron in layer 1 of the striate visual cortex in a 34‐day‐old kitten suggest that such neurons may be involved in local circuits that contribute to the formation of pyramidal cell receptive fields.
Abstract: We have recorded from a small neuron in layer 1 of the striate visual cortex in a 34-day-old kitten. It had a simple, orientation-selective receptive field that was nondirectional and showed length summation. The neuron was injected intracellularly with horseradish peroxidase. Computer-aided reconstruction revealed that it had a dense axonal plexus confined to layer 1, elongated in the anteroposterior dimension. By means of an antibody directed against a GABA-like antigen, and postembedding immunocytochemistry, the neuron was found to be strongly immunoreactive. The main input to soma and dendrites of the neuron was from synapses that were not GABA-L-immunoreactive, and probably originated from pyramidal cells. The axon of the cell formed synapses on dendritic shafts and spines, whose most likely sources were the apical tufts of pyramidal cell dendrites. These data suggest that such neurons may be involved in local circuits that contribute to the formation of pyramidal cell receptive fields.
27 citations