Hemisphere specialization of the animal brain for information processing principles

The origin of brain asymmetry and its psychotic reversal

Ontogenetic brain-asymmetry and its reversal in schizophrenia constitute special cases of a more fundamental principle of sensory-motor integration. Transmitted through an immature optical system, asymmetric inputs from the left visual field induce the infant's right hemispheric preference for lower spatial frequencies during early mother-child interaction. The emerging classical features of hemispheric specialisation later in life can be accounted for by a transformation law of the neuronal reference frames based on relativistic non-linear information processing. Accordingly, the asymmetric distributions of the cannabinoid receptor CB1 in the right basal ganglia and the left area of Wernicke reflect the preferences for lateralised posture, positioning, and speech. Epigenetic development of brain asymmetry thus unifies the different aspects related to cradling and breast-feeding, speech- and visuospatial processing, the dimensional conversion of spatiotemporal information and, in the case of a dysbalanced cannabinoid system, its psychotic reversal. The predicted right hemispheric shift and the inverse relationship between Kolmogorov entropy and its dimensional embedding (Shannon entropy) has ultimately been confirmed by non-linear EEG analysis of a fluoro-methyl-anadamide induced model psychosis splitting conscious from unconscious mental processes.

Effect of cerebral hemisphere decortication on the cytotoxic activity of natural killer and natural cytotoxic lymphocytes in the mouse

A comparison was made of the effects of left and right cerebral decortication on cytotoxic activity of natural killer and natural cytotoxic lymphocytes in the mouse. Natural killer cytotoxic activity was significantly reduced after right decortication, whereas left decortication led to a less pronounced, though still significant fall. The cytotoxic activity of natural cytotoxic cells, on the other hand, was significantly increased, particularly 15 days after left decortication. These findings mirror the results of previously published personal findings following electrothermocoagulation of the hypothalamus. The suggestion is made that the cortex and the hypothalamus form an integrated system for the control of certain aspects of natural immunity.

The development of visual lateralization in the domestic chick

In the domestic chick the visual systems fed by right and left eye differ already on day 2 in the way in which they analyse stimuli. The right eye system (RES) tends to use conspicuous cues to assign stimuli to categories whilst the LES is interested in all properties of stimuli including position in space. As early as testing is possible, the LES shows advantage in the use of topographical cues, and the RES in distinguishing food from other targets. Sharp changes in the ability of RES or LES to take charge of behaviour follow: on day 8 RES controls response even in tasks where the LES usually has advantage. Rapid change then follows: by day 10 the LES is able to control behaviour under appropriate conditions. In natural broods the sudden appearance of exploration away from the mother on day 10 may result from this change. Such periods of control by one eye system may allow intensive appropriate learning. The timing of the transition is the same in both sexes, even though females behave in almost all tasks as though the LES were less specialized (or more under the control of RES).

New evidence on the callosal system

In the present paper experimental data on the principles of functional organization of the animal callosal system and the roles of symmetry and asymmetry in interhemispheric interaction are considered. A conclusion has been made that the cerebral hemispheres function not according to homotopicity principle but according to the principle of heterotopicity. A utilization of both homotopical callosal projections and intracortical pathways takes place. In interhemispheric relations the major role is played by the principle of the common pathway. Of great importance in asymmetry organization is the physiological dominant, which is formed and reinforced by excitation spreading through the corpus callosum and along intracortical pathways. Transcallosal excitation, interacting with thalamocortical and extracallosal ones, contributes to the creation and modulation of functional interhemispheric asymmetry.

Hemisphere lateralization of the extrapolation reflex

The interhemispheric asymmetry of extrapolation task solution in infant and adult Norway rats (Rattus norvegicus) was investigated. L. V. Krushinsky's technique with a screen was used in combination with hemisphere inactivation by means of spreading depression. It was shown during a short-term adaptation to the experimental conditions, in extrapolation of movement direction at its multiple presentation, that the left hemisphere dominated in infant rats and the right one in adult rats. An additional adaptation caused the change of the asymmetry sign in the adult animals, which is discussed in terms of prevalence of the visuospatial or the rational component of the extrapolation task.

Humans, apes and monkeys: the changing neuropsychological viewpoint

Four areas (cognitive capacity, cerebral lateralization, the structural basis of amnesia, and disorders of reaching with parietal lesions) are reviewed with respect to comparative differences between human and non-human primates in 1963 and two decades later. It is concluded that in all four areas the discontinuities very clearly evident in 1963 have either been resolved or have become blurred. It is argued that this trend was furthered by Hécaen's editorial policy for Neuropsychologia and that clinical neuropsychology and experimental (animal) neuropsychology can be expected to converge increasingly during the next 20 yr.