Discusses the neurobiological basis for functional specialization of the cerebral hemispheres, indicating that the size of the corpus callosum is correlated with the neurophysiological measure of hand preference. In postmortem examinations of 42 subjects there were no sex differences, but mixed-handers had significantly larger total areas of the…

Provides comments on research studies related to memory systems, considering those exploring the nature of memory traces. One researcher suggests that memory trace circuits are extremely localized (as opposed to being diffuse), such that a lesion in a rabbit's brain can completely destroy the trace for a particular learned response. (JN)

Proposes a hypothesis suggesting that parts of the central nervous system that contain norepinephrine and dopamine are dynamically interrelated under stressful conditions in a compensatory way. (MLH)

Presents a hypothesis about the biochemical processes involved in memory storage. The postulated mechanism is initiated by a signal that is unusual but not unlikely to occur and produces an irreversible change in a key component of synaptic chemistry. Other features of the mechanism and experiments supporting the hypothesis are considered. (JN)

Shows that the perceived shade of gray depends on the luminance relationship between surfaces perceived to be in the same plane and not between surfaces that are merely adjacent in the retinal image. This implies that lateral inhibition cannot explain lightness constancy. (MLH)

Reviews the features of two classes of learning theories. Reports evidence supporting a statistical configuration" theory, suggesting that temporal patterns of neurophysiological waves in the average activity of extensive anatomical brain regions may constitute the basis of subjective experience. (AL)

It has recently been shown that perceived motion, in the absence of any appropriate retinal motion, is a sufficient stimulus to generate smooth pursuit eye motions. However, three experiments show that perceived motion is not necessary for pursuit, but that retinal motion always governs pursuit. (BB)

This letter is polemic. It has been proposed that developmental dyslexia is associated with bilateral hemispheric representation of spatial function that interferes with specialized left hemispheric processing of linguistic information. The data presented, however, may not warrant this conclusion. (BB)

Reports on recent research into the operation of neuronal local circuits in higher brain functions. (CP)

Reports the detection of magnetic fields associated with the flow of electric current in the human brain in response to electrical stimulation of the fingers. (SL)

Describes the subdivisions of the human peri-Sylvian language cortex which were determined by stimulation mapping during craniotomies of four adult patients. (SA)

Progress is now being made toward ascertaining the specific effects of rearing conditions on brain and behavior, the properties of the environment that contribute to these effects, and the developmental periods in which brain tissue is most sensitive to environmental modification. (Author/RH)

Electroencephalograms were analyzed during performance of verbal and spatial tasks. Complex scalp distributions of theta-, beta-, and, to a lesser extent, alpha-band spectral intensities discriminated between the two members of a pair of tasks, such as writing sentences and Koh's block design. (Author/BB)