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Matthews, J. (1994). Neurobiology of Visual Perception: Oscillatory Responses in Cat Visual Cortex Exhibit Inter-Columnar Synchronization Which Reflects Global Stimulus Properties. C. M. Gray; P. Konig; A. Engel; W. Singer. Nature. 338, 1989. Pp. 334-337.. Psychoanal Q., 63:394-395.
Psychoanalytic Electronic Publishing: Neurobiology of Visual Perception: Oscillatory Responses in Cat Visual Cortex Exhibit Inter-Columnar Synchronization Which Reflects Global Stimulus Properties. C. M. Gray; P. Konig; A. Engel; W. Singer. Nature. 338, 1989. Pp. 334-337.
Synchronization of Oscillatory Neuronal Responses in Cat Striate Cortex: Temporal Properties. C. M. Gray; A. Engel; P. Konig; W. Singer. Visual Neurosciences. VIII, 1992. Pp. 337-347.
Previous work by this group and others has demonstrated that neurons of the cat striate cortex respond to their preferred stimuli with rhythmic spike activity at a frequency of 40-60 cycles per second (40-60 Hz). Furthermore, nearby neurons which share the same stimulus selectivity have synchronized oscillatory responses
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(hence the extracellular local field potentials also show stimulus-selective oscillatory activity which is strongly correlated with the single or multiunit response).
The first study examines the degree of response synchronization between neurons in separate cortical columns as a function of both stimulus characteristics and the distance of cortical separation. Multiunit activity and local field potentials were recorded by extracellular electrodes in the striate cortex of anesthetized adult cats. Of 199 recording sites, 132 were judged to show oscillatory activity. Cross-correlational analysis for pairs of sites with oscillatory responses often demonstrated synchronization of this oscillatory activity at spatially separate cortical sites. The probability of synchronization between sites depended on the distance between sites and the similarity of preferred stimulus orientation of the sites. Sites with different visual fields but common orientation preference were observed to respond with phase-locked oscillatory activity, especially if the presented stimulus bridged both visual fields. These data are consistent with the notion that synchronization provides a mechanism for "extraction and representation of global and coherent features" of a visual stimulus.
The second study builds on these observations of synchrony by investigating in detail the fine temporal patterns for episodes of phase-locked oscillatory activity at distant sites. Once again multiunit activity and local field potentials were simultaneously recorded at several sites in cat striate cortex. Twenty pairs of sites were selected for temporal analysis of the local field potentials. Within each pair the sites were at least 5 mm apart (representing different areas of the visual field), and each site showed robust stimulus-dependent oscillatory response. The analysis used a moving-window technique to sequentially examine a series of 100 msec epochs, shifted stepwise by 30 msec increments, to examine the entire 6 sec stimulus period. This allowed a determination of the frequency, duration, and phase of episodes of correlated activity between paired sites. Synchronized oscillation events were transient, often forming, collapsing, and reforming during a stimulus period. The authors suggest that these events reflect transient linkages between distributed cell assemblies that form and dissolve as different aspects of the visual image are processed.
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Matthews, J. (1994). Neurobiology of Visual Perception. Psychoanal. Q., 63:394-395