Research ReportAuditory signal detection appears to depend on temporal integration of subthreshold activity in auditory cortex

The threshold of hearing decreases with increasing sound duration up to a limit of a few hundred milliseconds, whereas other auditory time constants are orders of magnitude shorter. A possible solution to this resolution-integration paradox is that temporal integration occurs more centrally than computations depending on high temporal resolution. But this would require information about subthreshold events in the periphery to reach higher centers. Here we show that this prerequisite is fulfilled. The auditory evoked response to a just perceptible pulse series does basically not depend on whether single pulses are below or above behavioral threshold. The failure to find evidence of temporal integration up to response latencies of 30 ms suggests that the integrator is located more centrally than primary auditory cortex. By using noise to its advantage, the auditory system apparently has established a central integration mechanism that is about as efficient as the peripheral one in the visual system.

Research Highlights► A series of subthreshold pulses elicits a well-structured auditory evoked response. ► There is no evidence of temporal integration up to response latencies of 30 ms. ► Temporal integration appears to occur more centrally than primary auditory cortex.