Journal of Neuroscience, Vol 9, 1150-1162, Copyright © 1989 by Society for Neuroscience
Cortical areas involved in horizontal OKN in cats: metabolic activity
SJ Herdman, RJ Tusa and CB Smith
Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins Hospital, Baltimore, Maryland 21205.
Cerebral cortex improves optokinetic responses to high target velocities,
but the specific cortical areas involved are unknown. Using the
14C-deoxyglucose technique, we compared local rates of cerebral glucose
utilization in cats viewing a moving optokinetic nystagmus (OKN) drum
(experimental group) with those in cats viewing a stationary OKN drum
(control group). In the experimental group, glucose utilization was
increased in areas 17 and 18 and in 4 areas in suprasylvian cortex (21a,
21b, PMLS, and VLS). There were no changes in glucose utilization in areas
7, 19, 20a, 20b, ALLS, AMLS, DLS, PLLS, the posterior suprasylvian area,
and the splenial visual area. The increases in glucose utilization in areas
17 and 18 were most significant in the granular layers (inner III and IV).
In areas 21a, 21b, PMLS, and VLS, the increases in glucose utilization
extended from layers II through V. There was also a regional distribution
of the increase in glucose utilization within each of these areas in the
experimental animals. The increase in glucose utilization did not include
the rostral portion of PMLS or the borders between areas PMLS and 21a, and
VLS and 21b. In addition, there was a smaller increase in glucose
utilization at the borders between areas 17 and 18 than in other portions
of these 2 areas. The results indicate that areas 17, 18, 21a, 21b, PMLS,
and VLS may be involved in the cortical modulation of horizontal OKN. The
laminar distribution of label within the cortical areas corresponds with
the distribution of projections from the dorsal lateral geniculate nucleus
to areas 17 and 18, and from areas 17 and 18 to PMLS. The regional
distribution of the metabolic activity within areas 17, 18, and PMLS
coincides with that portion of cortex expected to be excited by either the
spatial frequency of the stimulus or the retinalslip velocity (drum
velocity minus slow phase eye velocity) occurring during the eye movements.