PHASE-DEPENDENT MODULATION OF AUDITORY-EVOKED RESPONSES IN PRIMARY AUDITORY CORTEX AND CORPUS STRIATUM OF MONGOLIAN GERBILS

Perceptual processing, including sensory-input-based decision-making, is increasingly recognized to depend on the internal state of ongoing neural activity at the time of sensory input. In the sensory cortices, oscillatory phase has been proposed to gate information flow and shape stimulus processing. The role of ongoing activity for sensory processing in brain structures that show sensory evoked activity, but are not typically considered "sensory areas" is less understood. In this study, we investigate whether auditory-evoked responses in primary auditory cortex (A1) and corpus striatum depend on the phase of ongoing neural oscillations across multiple frequency bands (theta, alpha, and beta) at stimulus onset. Awake, passive listening, Mongolian gerbils (Meriones unguiculatus) were presented with pure tones ranging from 250 Hz to 8 kHz in frequency, while local field potentials (LFP) were recorded simultaneously from cortical and striatal sites using chronically implanted multi-electrodes. By comparing stimulus-evoked responses across stimulus frequencies and brain regions, we investigated the effect of instantaneous oscillatory phase of band-limited ongoing neuronal activities on various parameters characterizing the auditory-evoked response on the LFP level. Time–frequency and phase-resolved analyses were used to quantify relationships between oscillatory phase at stimulus onset and response amplitude, latency, and spectral dynamics. This approach enables systematic comparison of phase-dependent effects across oscillatory bands, stimulus frequencies, and cortico-striatal circuits, with potential relevance for temporally precise closed-loop stimulation strategies in neuroprosthetic devices.