Biased competition through variations in amplitude of γ-oscillations

Magteld Zeitler,Pascal Fries,Stan Gielen

doi:10.1007/s10827-007-0066-2

Magteld Zeitler, Pascal Fries + Show 1 more

Open Access

https://doi.org/10.1007/s10827-007-0066-2

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Abstract

Experiments in visual cortex have shown that the firing rate of a neuron in response to the simultaneous presentation of a preferred and non-preferred stimulus within the receptive field is intermediate between that for the two stimuli alone (stimulus competition). Attention directed to one of the stimuli drives the response towards the response induced by the attended stimulus alone (selective attention). This study shows that a simple feedforward model with fixed synaptic conductance values can reproduce these two phenomena using synchronization in the gamma-frequency range to increase the effective synaptic gain for the responses to the attended stimulus. The performance of the model is robust to changes in the parameter values. The model predicts that the phase locking between presynaptic input and output spikes increases with attention.

Highlights

Our retinas are constantly stimulated by an overwhelming amount of information and the brain faces the task of reducing a potentially overloading amount of information into a manageable flow that reflects both the current needs of the organism and the external demands placed on it
Since it is well known that the excitatory input in visual cortex from V1 to V2 and from V2 to V4 contains gamma frequency oscillations (Eckhorn et al 1993; Frien et al 1994; Maldonado et al 2000), we have explored the possible role of gamma frequency oscillatory input in stimulus competition and selective attention
The simulation results will be described for the firing rate of the output neuron Y (Section 3.2) and the coherences between the spikes of the output neuron and each of the stimulus-related inputs to the populations of Poisson neurons (Section 3.3)

Summary

Introduction

Our retinas are constantly stimulated by an overwhelming amount of information and the brain faces the task of reducing a potentially overloading amount of information into a manageable flow that reflects both the current needs of the organism and the external demands placed on it. In order to solve this problem, the brain uses a strategy to select the relevant information and to suppress information which is not relevant. If just one single stimulus falls within the receptive field of a neuron, this stimulus can be attended or not, and in the latter case a stimulus outside the receptive field may be attended. Since higher cortical areas have large receptive fields (Smith et al 2002), it is quite common that two (or even more) stimuli fall within the receptive field of a neuron. In that case one of them can be attended (selective attention) or none of them. In order to understand the neuronal substrate of attention, many single-unit studies in visual cortex have investigated how attended and unattended stimuli are encoded in the firing rate of neurons

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