Athanassios Siapas

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Integration of inputs by cortical neurons provides the basis for the complex information processing performed in the cerebral cortex. Here, we have examined how primary visual cortical neurons integrate classical and nonclassical receptive field inputs. The effect of nonclassical receptive field stimuli and, correspondingly, of long-range intracortical(More)
We demonstrate a detailed visual cortical circuit which exhibits robust contrast adaptation properties, consistent with physiological observations in V1. The adaptation mechanism we employ is activity-dependent synaptic depression at thalamocortical and local intra-cortical synapses. Model contrast response functions CRF shift so that cells remain maximally(More)
The traditional concept of the receptive eld e.g., 4, 66 holds that each portion of the receptive eld RF, in response to a stimulus element, has unitary excitatory or in-hibitory innuence on neuronal response. Here, we argue: i receptive eld components naturally have dual or vector both excitatory and inhibitory innuence; ii neuronal integration is better(More)
A general feature of the cerebral cortex is its massive i n terconnec-tivity-it has been estimated anatomically 15 that cortical neurons receive on the order of 10,000 synapses, the majority of which originate from other nearby cortical neurons. Numerous experiments in primary visual cortex V1 have revealed strongly nonlinear interactions between stimulus(More)
Computations in brain circuits involve the coordinated activation of large populations of neurons distributed across brain areas. However, monitoring neuronal activity in the brain of intact animals with high temporal and spatial resolution has remained a technological challenge. Here we address this challenge by developing dense, three-dimensional (3-D)(More)
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