Figure 2.

Selective attention increases both the gain and selectivity of auditory-cortex neural populations. (a) Target tones (red color) were either higher in frequency or longer in duration. Background gray represents the noise masker and the white area represents notch in the noise. (b) Bell-shaped curves represent the presumed single-neuron receptive fields (RFs) during baseline (Ignore) and the proposed attention-dependent changes in the RFs (increased gain versus narrowing of RFs versus both effects). It is assumed that noise suppresses responsiveness of the neuron to the 1 kHz tone as a function of its overlap with the receptive field of auditory-cortical neuron, with the red-colored area below the bell-shaped curve indicating how likely the neuron is to respond to the 1 kHz probe sound. In the white-noise condition, it is assumed that only neurons optimally tuned to the tone respond. (c) Simulated effects at the level of neuronal population responses as a function of notch width. Note that with the “gain only” mechanism, the amplitude-reduction function remains identical between the stimuli endpoints and is only scaled differentially, while the other mechanisms result in modulation of the basic shape of the amplitude reduction function. (d) Amplitudes at N1 response peak latency showed nonmultiplicative suppression with narrowing of the notch in the noise masker during selective-attention. Comparison with the three alternative models suggested that both increased gain and enhanced selectivity take place during auditory selective-attention. Adapted with permission from [91].