Attention increases neural selectivity in the human lateral occipital complex

It is well established that attention increases the efficiency of information processing, but the neural mechanisms underlying this improvement are not fully understood. Evidence indicates that neural firing rates increase for attended stimuli, but another possibility is that attention could increase the selectivity of the neural population representing an attended stimulus. We tested this latter hypothesis by using functional magnetic resonance imaging (fMRI) to measure population selectivity for object views under different attention conditions in the human lateral occipital complex (LOC). Our data not only show increased neural activity (or 'gain') with attention, consistent with existing models, but also increased population selectivity that cannot be accounted for by gain mechanisms alone. Our results suggest that attention increases the specificity of the neural population representing an attended object.