Horizontal interactions between visual cortical neurones studied by cross-correlation analysis in the cat

Area of Science:

• Neuroscience
• Visual Cortex Research
• Neural Circuitry

Background:

• Horizontal neural connections are crucial for information processing in the visual cortex.
• Understanding these connections within a hypercolumn provides insight into visual processing mechanisms.

Purpose of the Study:

• To investigate the functional significance and extent of horizontal neural connections within a hypercolumn of the cat visual cortex.
• To classify the types of interactions mediated by these horizontal connections.

Main Methods:

• Cross-correlation analysis of simultaneously recorded spike trains from pairs of neurons.
• Analysis of neuronal separation, laminar location, orientation preference, and eye preference.

Main Results:

• Sixty-eight out of 327 cell pairs showed significantly correlated firings, classified into excitatory, inhibitory, and common input interactions.
• Common inputs were most frequent, followed by excitatory interactions (often with common inputs), and least frequent inhibitory interactions.
• Correlated firings were prominent within 400 microns and between cells with similar receptive field properties (orientation and eye preference), with inhibitory interactions showing a slight preference for differing orientation preferences.

Conclusions:

• Horizontal functional interactions in the visual cortex hypercolumn are primarily localized within approximately 400 microns.
• These interactions effectively link cortical cells with similar receptive field properties, with exceptions for inhibitory interactions.
• The findings elucidate the spatial and functional organization of local horizontal circuitry in the visual cortex.