Optimal attentional modulation of neural population

Frontiers in Computational Neuroscience

Laurent eItti¹  Ali eBorji² 

[1] University of Southern California (USC);University of Southern California;

关键词: Attention;    Classification;    Neuron;    visual search;    feature selectivity;    gain modulation;   

DOI  :  10.3389/fncom.2014.00034

来源: DOAJ

【 摘 要 】

Top-down attention has often been separately studied in the contexts of either
optimal population coding or biasing of visual search. Yet, both are intimately
linked, as they entail optimally modulating sensory variables in neural populations
according to top-down goals. Designing experiments to probe top-down attentional
modulation is difficult because non-linear population dynamics are hard
to predict in the absence of a concise theoretical framework. Here, we describe
a unified framework that encompasses both contexts. Our work sheds light onto
the ongoing debate on whether attention modulates neural response gain, tuning
width, and/or preferred feature. We evaluate the framework by conducting simulations
for two tasks: 1) classification (discrimination) of two stimuli sa and sb
and 2) searching for a target T among distractors D. Results demonstrate that all
of gain, tuning, and preferred feature modulation happen to different extents, depending
on stimulus conditions and task demands. The theoretical analysis shows
that task difficulty (linked to difference D between sa and sb, or T and D) is a
crucial factor in optimal modulation, with different effects in discrimination vs.
search. Further, our framework allows us to quantify the relative utility of neural
parameters. In easy tasks (when D is large compared to the density of the neural
population), modulating gains and preferred features is sufficient to yield nearly
optimal performance; however, in difficult tasks (smaller D), modulating tuning
width becomes necessary to improve performance. This suggests that the conflicting
reports from different experimental studies may be due to differences in
tasks and in their difficulties. We further propose future electrophysiology experiments
to observe different types of attentional modulation in a same neuron.

【 授权许可】

Unknown