[Spreading depression in a waking rabbit with the spectral EEG analysis]

Area of Science:

• Neuroscience
• Electrophysiology

Context:

• Cortical spreading depression (SD) is a wave of neuronal and glial depolarization.
• Understanding SD dynamics is crucial for neurological research.
• High-frequency gamma activity in electroencephalography (EEG) reflects cortical function.

Purpose:

• To investigate the manifestation of SD in cortical gamma activity using bipolar EEG analysis.
• To characterize the temporal dynamics and spatial spread of SD waves.
• To explore how SD propagation patterns change in long-term experiments and under different conditions.

Summary:

• Bipolar EEG analysis of monopolar recordings revealed prominent SD phenomena.
• SD waves were consistently associated with a significant decrease in gamma band power (37-47 Hz) across cortical areas.
• The study determined the timing and spread of SD by analyzing the decline in gamma activity power.
• Long-term experiments showed altered SD propagation, with changes in latency and occasional disturbances.
• Rapid SD onset across the dorsal neocortex was observed after KCl injection.
• Delayed or absent SD waves, along with epileptiform activity, suggested increased cortical functional inhomogeneity.
• Spectral EEG analysis in awake rabbits provided insights into both normal and abnormal SD propagation.

Impact:

• This study enhances the characterization of SD using spectral EEG analysis.
• Findings reveal alterations in SD propagation, suggesting underlying changes in cortical excitability and functional connectivity.
• The research provides a method to identify normal and aberrant SD events, aiding in the study of neurological conditions.