Metrics for Cortical Map Organization and Lateralization
Bulletin of Mathematical Biology 60 (1998), 27-47
Sergio A. Alvarez
Center for Nonlinear Analysis and
Department of Mathematical Sciences
Carnegie Mellon University
Pittsburgh, PA 15213-3890
Svetlana Levitan, James A. Reggia
Department of Computer Science and
Institute for Advanced Computer Studies
University of Maryland
College Park, MD 20742
Abstract
Cerebral lateralization refers to the poorly understood fact that
some functions are better controlled by one side of the brain than
the other (e.g. handedness, language). Of particular concern
here are the asymmetries apparent in cortical topographic maps
that can be demonstrated electrophysiologically in mirror-image
locations of the cerebral cortex. In spite of great interest
in issues surrounding cerebral lateralization, methods for measuring
the degree of organization and asymmetry in cortical maps are currently
quite limited. In this paper, several measures are developed
and used to assess the degree of organization, lateralization,
and mirror symmetry in topographic map formation.
These measures correct for large constant displacements as well as
curving of maps. The behavior of the measures is tested on
several topographic maps obtained by self-organization of
an initially random artificial neural network model of a
bihemispheric brain, and the results are compared with
subjective assessments made by humans.