Spatial patterns of visual cortical fast EEG during conditioned reflex in a rhesus monkey

Area of Science:

• Neuroscience
• Computational Neuroscience
• Electrophysiology

Background:

• Time-space coherence patterns in fast EEG activity have been described in the olfactory bulb.
• These olfactory coherences are linked to specific behaviors.
• The current study investigates similar patterns in the visual cortex.

Purpose of the Study:

• To investigate the existence and characteristics of time-space coherence patterns in the visual cortex EEG of a Rhesus monkey.
• To compare these patterns with those previously observed in the olfactory bulb.
• To determine if these patterns are associated with visual conditioned stimuli (CS) and conditioned responses (CR).

Main Methods:

• Simultaneous recording of EEG from 16-35 subdural electrodes over the left occipital lobe in a Rhesus monkey.
• Analysis of 1.5-second EEG segments during visual CS and CR.
• Principal Components Analysis (PCA) to extract dominant common waveforms and spatial distribution (factor loadings).

Main Results:

• EEG activity showed irregular bursts (75-200 ms) with peak frequencies in the 20-40 Hz range, resembling '1/f noise'.
• Distinct spatial patterns of coherent activity were identified and associated with the visual CS and CR.
• These patterns demonstrated stability over a 6-week recording period.

Conclusions:

• The visual cortex exhibits time-space coherence patterns similar to those found in the olfactory system.
• These patterns are linked to behavioral processing (CS and CR) and are stable over time.
• The findings suggest that such cortical EEG patterns may be detectable using non-invasive scalp electrodes.