Anisotropy of ongoing neural activity in the primate visual cortex

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• The mammalian neocortex exhibits significant anatomical variation in its tangential and radial dimensions.
• Understanding neural activity coherence across these dimensions is crucial for deciphering cortical processing.
• Previous research has explored local field potential (LFP) coherence, but a comparative analysis across cortical extents is needed.

Purpose of the Study:

• To compare and contrast the spatial profile of neural activity coherence across tangential and radial cortical dimensions.
• To investigate the relationship between interelectrode distance and LFP coherence along the cortical surface and across cortical layers.
• To determine if the spatial pattern of LFP coherence is influenced by behavioral state (rest vs. task).

Main Methods:

• Analysis of ongoing local field potential (LFP) data from simultaneous multi-site recordings in the primary visual cortex.
• Experiments utilized electrode configurations spaced along the cortical surface and at different laminar positions.
• Comparison of LFP coherence falloff as a function of interelectrode distance in both experimental setups.

Main Results:

• LFP coherence diminishes with increasing interelectrode distance across both cortical dimensions.
• Tangential coherence declines gradually along the cortical surface.
• Radial coherence exhibits a discontinuous, compartmentalized pattern across cortical layers, with a distinct boundary between superficial and deep zones.

Conclusions:

• Cortical processing occurs in partially segregated laminar zones that extend tangentially.
• These zones are oriented orthogonally to cortical columns, suggesting a distinct organizational principle.
• Electrophysiological findings align with known anatomical organization of the cortical microcircuit.