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Developing effective behavioral and psychological mechanisms for coping with social stress was very important in human evolution because humans evolved as social beings. The aggressive and post-aggressive behavior of 30 boys aged 7-11 years was observed during free play in summer camp with the standard "post-conflict-matched control" method (de Waal and Yoshihara, 1983). The focals were the victims of the conflict. Saliva samples for examination of cortisol and dehydroepiandrosterone sulfate levels were taken from each boy in 5 cases: 10 minutes after a conflict with and without reconciliation, matched-control samples next day and morning samples for the basal level. Every boy filled in a sociometry form, Buss-Durkee Hostility Inventory, Eysenk Personality test and the Revised Children's form for the Manifest Anxiety Scale. The stress-reduction role of peacemaking was supported on the physiological level. The level of stress-related hormones was higher when no reunion occurred.

Viability of astrocyte grafts introduced into CA1 pyramidal layer of the left dorsal hippocampus after injection of kainic acid into this brain region and the effects of these grafts on the hippocampus and amygdala were studied on Wistar rats. In rats with astrocyte grafts the degree of destruction in fields CA1-CA2 of the dorsal and ventral hippocampus, fields CA3-CA4 of the ventral hippocampus, and central and basolateral amygdala was lower compared to animals with kainic acid-induced hippocampal damage and control rats; destructions in the dentate fascia were absent. Our results suggest that astrocyte grafts stimulate neurogenesis in the mature brain of recipient rats with kainic acid-induced brain damage.

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The possibility to compensate the loss of olfactory and non-olfactory functions due to removal of the olfactory bulb by embryonal brain grafts was investigated in adult rats. Spatial working memory was examined in an 8-arm radial water maze task 6 weeks after bulbectomy. During 15 daily trials, performance gradually improved in bulbectomized controls (n = 10) and in rats with olfactory bulb transplants (n = 9), but did not attain that of intact controls (n = 10). No improvement was observed in the rats with substantia nigra grafts (n = 8). Eleven weeks after bulbectomy, the same rats were tested in the water tank navigation task. The performance improved during ten 12-trial sessions in bulbectomized rats less than in intact controls, but more than in the transplanted rats. The olfactory food retrieval test performed 14 weeks after bulbectomy revealed almost full recovery of smell in bulbectomized rats, but not in the transplanted animals. It is concluded that the spatial memory deficit is probably due to bulbectomy-induced interference with septohippocampal function which is not alleviated, but rather enhanced by transplantation. The results suggest that the effect of brain grafting is not always beneficial.