Spiking Activity in the Auditory Cortex Is Synchronized to Beta-Band Local Field Potential Oscillations

The extraction of temporal information from sensory input streams is of paramount importance in the auditory system. In this study, amplitude modulated sounds were used as stimuli to drive auditory cortex neurons of the bat species Carollia perspicillata, in order to assess the interactions between cortical spikes and local-field potentials (LFPs) for the processing of temporal acoustic cues. We show that the occurrence of cortical spikes is synchronized to beta-band (12-30 Hz) LFP oscillations, and that the latter is independent of the temporal modulation of the sound that triggers the spikes. Spike activity can track amplitude modulation rates only if they are lower than 30 Hz, while LFPs can be entrained by acoustic streams modulated at frequencies higher than 100 Hz. The presented data indicate that coherent beta-band oscillations in the auditory cortex are intrinsically related with stimulus-locked phasic neuronal discharges.