Synchronized Oscillations as the Neural Correlate of Consciousness
Document Type:ASSC Conference Item
Topics:Neural Correlates of Consciousness
Keywords:Neural correlate of consciousness. Neural synchrony and binding. Brain oscillations. Heirarchical neural processing. Visual perception. Distributed memory. Neural networks. Mirror neurons.
Deposited by:M.D. John Lin
Date of Issue:2008
Event Dates:18-22 Jun 2008
Event Location:Taipei, Taiwan
Event Title:ASSC-12 Conference
Event Type:ASSC Conference
Number of Pages:17
Abstract:Modularization and hierarchical processing appear to be general features of all cortical processing. Using the processing of visual information as an example, this paper proposes a general model of hierarchical processing to explain how information from specialized visual areas--those processing lines, colors, motion, and so on--is integrated (and, in many instances, combined with information from other modalities, such as auditory, tactile, and semantic perceptions) to decipher the identity of an object. In the model, specialized modules are organized by hierarchical levels stacked together in a pyramidal configuration. A specialized module processes information received from subordinates at lower levels and passes the result to its superior at the next higher level. Information becomes progressively more concise, and meaningful, as it flows from the bottom of the pyramid toward the top. In the visual system, information from the retina enters the bottom level (area V1) of the pyramid, and the processed result emerges at the top (the visual association cortex). The resultant high-level representation then becomes available in conscious awareness (or the imaginary thinking theater of the mind) to interact and correlate with data from other modalities to achieve perceptual unity and understanding. In the hierarchy, feedforward pathways are frequently accompanied by reciprocal feedback pathways. Feedback pathways also exist among many levels of the hierarchy. These feedback circuits are used to provide mental predictions from higher-level representations and to exert top-down influence. Their presence sets up circular loops of feedforward and feedback circuits in the hierarchy, which create synchronized oscillations at the moment of perceptual recognition. This occurs because, in a steady state, when the perceptual result is correct--that is, when the perceptual result corresponds to the mental image in conscious awareness, as corroborated by results from other cortical modalities--predictions (feedback signals) will match input signals to the modules at all levels of the hierarchy, and the entire circuitry will oscillate in synchrony. The syncrony is broken when conscious attention is disengaged to attend to other matters.