BIDIRECTIONAL INFORMATION FLOW IN MONKEYS VISUAL CORTEX,

Hualou Liang, Mingzhou Ding, Steven L. Bressler

Center for Complex Systems & Brain Sciences, Florida Atlantic U., Boca Raton, FL 33431

Macaque monkeys were trained to perform a visuomotor pattern discrimination task based on differences in visual pattern. Local field potentials recorded simultaneously from striate cortex, prestriate cortex and inferior temporal cortex were examined on a millisecond time scale. With the use of an analysis based on multivariate regression theory, we found that during processing of right or left slanted diamond or line patterns, bi-directional flow of neural information between cortical areas occurred with different onset timing. The flow of visual information originated in striate cortex, diverged within prestriate cortex, and coursed into the inferior temporal cortex. By contrast, a reversed-direction information flow, with delayed onset at each stage, was observed. Furthermore, these bi-directional information flows were predominant at 12 Hz.Our results clearly show dual dynamical interactions, occurring in the alpha range, between cortical areas at three hierarchical levels in the visual system. These dynamic interactions may subserve bottom-up and top-down functions postulated by many theories of visual perception. Supported by NIMH, NSF and ONR.