Forward suppression in the auditory cortex is frequency-specific.
Bottom Line: The temporal order and frequency proximity of sounds influence both their perception and neuronal responses.These effects are larger when the two sounds are spectrally similar.These data are consistent with the idea that cortical neurons receive convergent inputs with a wide range of tuning properties that can adapt independently.
Affiliation: MRC Institute of Hearing Research, University Park, Nottingham NG7 2RD, UK.Show MeSH
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Mentions: The tuning of suppression became wider as the distance between the probe tone frequency and the CF increased. This is shown for the population data at zero ISI in Fig. 7A, as a function of the SCF. The QERB of forward suppression for probes more than half an octave away from the unit excitatory CF (grey) are slightly, but significantly (one-way anova: P < 0.01), lower than those nearer to CF (black). Also shown for comparison are the QERB values for the excitatory RFs from the same cortical units (grey coarsely-dashed line) and for a function describing the tuning at the level of the auditory nerve (grey finely dashed line; Evans, 1992). This makes it clear that the suppressed tuning is broad relative to the periphery, and more comparable with excitatory RFs regardless of the frequency of the probe. Figure 7B shows the mean QERBs across the population as ISI varies, when the probe tone frequency is within 0.5 octaves of CF (solid black line) or more than 0.5 octaves from CF (solid grey line). Thus, at all delays, probes placed further away from CF could be suppressed by a wider range of conditioner frequencies.
Affiliation: MRC Institute of Hearing Research, University Park, Nottingham NG7 2RD, UK.