INTERACTION OF PREFRONTAL CORTEX AND INFERIOR COLLICULUS DURING BEHAVIORAL TESTING RATS IN AN AUDITORY ODDBALL PARADIGM

Detecting behaviorally relevant sounds is crucial in dynamic environments. Beyond sensory processing in the auditory pathway, the medial prefrontal cortex (mPFC) may exert context-dependent control. We combined a three-class auditory oddball task, in which rats responded to target tones and ignored standard and distractor tones, with simultaneous neural recordings from the mPFC and inferior colliculus (ICc) to assess their interaction during auditory processing in rats.
After training, eight rats received chronic electrodes in the mPFC and ICc. Local field potentials were recorded during an auditory oddball task in which rats responded to a rare 5 kHz target tone while ignoring a frequent 3 kHz standard and a rare 1.5 kHz distractor. Neural activity was assessed using event-related potentials (ERPs), Morlet wavelet–based time–frequency analysis, and trial-by-trial Pearson cross-correlation.
ERPs revealed an early ICc onset response for all tones (20–50 ms), accompanied by increased beta (12–30 Hz) and gamma (>30 Hz) activity. In the mPFC, early (∼100 ms, N1) and late (300–450 ms, P3) components were strongest for targets. Low-frequency activity (<12 Hz) followed all tones in mPFC, but beta responses were target-specific. Only targets induced a second ICc response sharing spectral features with the mPFC N1. Cross-correlation showed a target-specific shift of information flow from mPFC to ICc after the N1.
The similarity of spectral features of the mPFC N1 and subsequent ICc activation suggests a model in which prefrontal activity selectively amplifies auditory midbrain representations of behavioral relevant stimuli via top down pathways.