Consciousness and the neurobiology of perceptual binding

The brain processes information along specialized tracts that are separated across cortex. However, our visual experiences are of unified objects. How our perceptions become united into wholes even though all individual features that comprise them are distributed about the brain is the problem of perceptual binding. This article discusses ongoing neurophysiological research that connects perceptual awareness with 40 Hz neural oscillatory firing patterns. Three different experimental approaches for tying 40 Hz oscillatory firing patterns in cortex to perceptual experiences are examined: (1) the single cell and local field potential recordings of visual areas 17 and 18 which show synchronous firing patterns between noncontiguous cells with similar receptive fields; (2) MEG measurements of rapid thalamic bursting, indicating that the ILN might drive or otherwise contribute to the cortical oscillations; and (3) EEG recordings taken over the sensory areas of cortex demonstrating a higher level of neural coordination, suggesting that perceptual binding occurs at a higher level of organization entirely. As of this writing, a connection between any 40 Hz oscillatory patterns and perceptual binding or consciousness is tenuous at best.