Long-range intralaminar noise correlations in the barrel cortex.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Cortical information processing relies on understanding neuronal firing correlations.
• Existing models assume high correlation within vertical columns and rapid decline with horizontal distance.
• Technical limitations have hindered direct evaluation of these assumptions.

Purpose of the Study:

• To investigate spike-count noise correlations between neocortical neurons.
• To determine the influence of laminar position and horizontal distance on neuronal firing.
• To critically evaluate established notions of cortical columnar organization.

Main Methods:

• Utilized 128-channel silicon probes for multi-neuron recordings in rat barrel cortex.
• Analyzed spontaneous activity and spike-count noise correlations.
• Employed eigen decomposition of correlation coefficient matrices to assess neuronal relationships.

Main Results:

• Neuronal laminar position significantly influences firing correlations; layer 5B/6 neurons show opposite fluctuations to layers 5A and 4.
• Horizontal correlations up to 1.5 mm are similar to vertical correlations within experiments.
• The effect of laminar position extends across multiple functional columns.

Conclusions:

• Neuronal laminar position is a crucial factor in cortical processing, overriding simple columnar assumptions.
• Cortical processing involves a dynamic balance between horizontal and vertical influences, modulated by brain states.
• Findings necessitate a revised understanding of how neuronal networks process information.