Effects of P2, a peptide derived from a homophilic binding site in the neural cell adhesion molecule on learning and memory in rats.

The neural cell adhesion molecule (NCAM) plays a pivotal role in neural development, regeneration, synaptic plasticity, and memory processes. P2 is a 12-amino-acid peptide derived from the second immunoglobulin-like (Ig) module of NCAM mediating cis-homophilic interactions between NCAM molecules present on the same cell. P2 is a potent NCAM agonist, capable of promoting neuronal differentiation and survival in vitro. The aim of this study was to assess the effect of P2 on learning and memory. Rats treated with P2 intracerebroventricularly (1 h prior to test) performed significantly better than controls in the reinforced T-maze, a test of spatial working memory. Further, rats treated with P2 exhibited decreased anxiety-like behavior while learning the T-maze task. In the social recognition test, both intracerebroventricular (1 h prior to test) and systemic (1 and 24 h prior to test) P2 treatment enhanced short-term social memory and counteracted (administration 24 h prior test) scopolamine-induced social memory impairment. In contrast, P2 (1 h prior to test) did not significantly improve long-term (24 h) retention of social memory, nor did it have any significant effects on long-term memory evaluated by the Morris water maze (administration between 2 days before training and 5.5 h posttraining). In the open field test, P2 (1 h prior to test) decreased general locomotion and rearing, but did not influence any other anxiety-related behaviors, indicating only a minimal influence on baseline anxiety levels. Taken together, these data indicate that in vivo P2 enhances short-term memory and protects against the amnestic effects of scopolamine, while modulating emotional behavior in a learning or novelty-related task.

A simple method for measuring brain asymmetry in children: application to autism.

A device for measuring signal transfer within and between hemispheres has been developed at the Center for Neuropsychological Research at the University of Trier, Germany. It contains two identical panels allowing both tactile stimulation and motor response with buttons for the fingers of each hand. The buttons have two functions. They can exert a slight tactile stimulation to a finger, and they can be pressed down by the finger to provide a motor response to the tactile stimulation allowing measuring the response time. The device was used for measuring brain asymmetry in tactile processing autistic children. The participants were given a finger tapping test followed by the procedures with unilateral and bilateral processing of tactile stimulation. All participants responded positively to the test procedure and accepted it as a kind of game. The results indicated that brains were more asymmetrical in autistic children than in controls: The right hemisphere functioned quicker than the left hemisphere.

The dynamics of two different tests of laterality in rats.

Female rats were tested for behavioural laterality in a T-maze (TM) and a "handling by the tail" (TH) test, and vaginal smears were taken every day. The two tests did not correlate. There was a population bias of left choices in TH, but in TM most of the animals were ambilateral. Statistical analysis showed that animal learning in successive trials influenced their lateral choice, but it was similar in both tests. The difference in lateral bias in rats in the two tests depended mostly on differences in internal laterality. Rats in proestrus had a left-side bias in TM. There was no dependency between direction of lateral choice in TH and estrus cycle.