A Quantitative Map of the Circuit of Cat Primary Visual Cortex

We developed a quantitative description of the circuits formed in cat area 17 by estimating the “weight” of the projections between different neuronal types. To achieve this, we made three-dimensional reconstructions of 39 single neurons and thalamic afferents labeled with horseradish peroxidase during intracellular recordings in vivo . These neurons served as representatives of the different types and provided the morphometrical data about the laminar distribution of the dendritic trees and synaptic boutons and the number of synapses formed by a given type of neuron. Extensive searches of the literature provided the estimates of numbers of the different neuronal types and their distribution across the cortical layers. Applying the simplification that synapses between different cell types are made in proportion to the boutons and dendrites that those cell types contribute to the neuropil in a given layer, we were able to estimate the probable source and number of synapses made between neurons in the six layers. The predicted synaptic maps were quantitatively close to the estimates derived from the experimental electron microscopic studies for the case of the main sources of excitatory and inhibitory input to the spiny stellate cells, which form a major target of layer 4 afferents. The map of the whole cortical circuit shows that there are very few “strong” but many “weak” excitatory projections, each of which may involve only a few percentage of the total complement of excitatory synapses of a single neuron.

Figure 3 from Physiology of Layer 5 Pyramidal Neurons in Mouse Primary Visual Cortex: Coincidence Detection through Bursting

Narrow and Broad γ Bands Process Complementary Visual Information in Mouse Primary Visual Cortex

Feedback pathways to the primary visual cortex. Top, Three different

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A Quantitative Map of the Circuit of Cat Primary Visual Cortex

A Quantitative Map of the Circuit of Cat Primary Visual Cortex

Primary visual cortex shows laminar‐specific and balanced circuit organization of excitatory and inhibitory synaptic connectivity - Xu - 2016 - The Journal of Physiology - Wiley Online Library

A Quantitative Map of the Circuit of Cat Primary Visual Cortex

Foundations of Vision » Chapter 6: The Cortical Representation

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A Quantitative Map of the Circuit of Cat Primary Visual Cortex