Neurophysiological Signatures of Major Depressive Disorder and Frontocentral Gamma Auditory Response Deficits

Area of Science:

• Neuroscience
• Psychiatry
• Auditory Neuroscience

Background:

• Aberrant gamma oscillations are implicated in major depressive disorder (MDD), but specific neural signatures remain unclear.
• Auditory steady-state responses (ASSRs) provide a robust method for probing gamma oscillations.
• This study investigates early auditory evoked potentials (AEPs) and sustained gamma ASSRs in MDD to identify neurophysiological markers.

Purpose of the Study:

• To characterize early transient auditory evoked responses (AEPs) and sustained gamma ASSRs in first-episode, drug-naïve patients with MDD.
• To identify reliable neurophysiological signatures of MDD using electroencephalography (EEG).
• To explore potential interpretations of gamma auditory response deficits in MDD.

Main Methods:

• EEG data were collected from 40 MDD patients and 41 healthy controls (HCs) using a 40-Hz ASSR paradigm with chirp and click stimuli.
• Source analysis of transient AEPs was performed to pinpoint early information processing deficits.
• Spectrotemporal and spatial characteristics of 40-Hz ASSRs were analyzed, including power, phase coherence, and functional connectivity.

Main Results:

• MDD patients exhibited reduced P200 amplitude in the middle temporal gyrus, suggesting impaired auditory perception.
• Attenuated 40-Hz power, phase coherence, and suppressed right frontotemporal/frontocentral connectivity were observed in MDD.
• Decreased right frontocentral connectivity correlated with anxiety severity, particularly with chirp stimuli.

Conclusions:

• Impaired gamma auditory responses are evident in first-episode, drug-naïve MDD patients.
• Right frontocentral connectivity, elicited by chirp stimuli, shows promise as a neurophysiological signature for predicting MDD symptoms.
• The chirp stimulus may be particularly effective in revealing specific neurophysiological markers of MDD.