The effects of vasopressin on memory processes in Java monkeys.

The roles of vasopressin (arginine-vasopressin) in controlling conditioned operant food-procuring reflexes and various types of memory were studied in monkeys. Types of memory were: conditioned reflex, image (Hunter-Kerr test), short-term, and long-term. The effects of vasopressin were assessed in terms of objective measures of higher nervous activity: movement and autonomous functions. These studies showed that administration of vasopressin to monkeys had different effects on simple operant food-procuring responses and memory processes. Vasopressin had greater effects on memory processes and the restoration of memory after functional derangements of higher nervous activity. The question of the formation of the two types of effect of vasopressin on higher nervous activity is discussed in relation to the evolution of mammals.

Comparative study of the roles of ACTH and beta-endorphin in regulating conditioned reflex activity in the hedgehog.

Data on the relative effects of the neurohormone ACTH1-39 and the opioid peptide beta-endorphin on conditioned reflex activity in the hedgehog are presented. It was demonstrated that administration of ACTH (30-50 micrograms/kg s.c.) led to facilitation of learning and strengthening of memory processes (conditioned reflex traces). ACTH promoted strengthening of movement, orientational-investigative, and intersignal activities, produced hyperalgesia, and blocked the effects of naloxone. Administration of beta-endorphin (30-40 micrograms/kg s.c.) lengthened the latent periods of conditioned reflexes, produced a pronounced analgesic effect, and reduced movement and intersignal activities. The effects of beta-endorphin were eliminated by dosage with naloxone. Administration of beta-endorphin blocked the inhibitor effects of stimulation of the limbic cortex; doses of ACTH produced partial release of inhibitory effects. The differences between the effects of ACTH and beta-endorphin on higher nervous activity are discussed, as are the possible mechanisms of these effects.

Comparative physiological features of the regulatory effect of vasopressin on higher nervous activity in an ascending series of mammals.

This report provides comparative physiological data on the features of the regulatory effects of the neurohormone vasopressin on higher nervous activity in an ascending series of mammals consisting of insectivores, rodents, and primates. Administration of vasopressin to hedgehogs produced a general facilitatory effect on conditioned reflex brain activity. The effects of vasopressin on memory processes in hedgehogs was minor. In rabbits, vasopressin had greater regulatory effects on conditioned reflex memory than in hedgehogs. However, this was transient in nature. In monkeys, administration of vasopressin had complex differential effects on simple conditioned responses and different types of memory. The effects of vasopressin on memory processes were long-lasting and were different for corticalized and noncorticalized forms of nervous activity. The question of changes in the nature of the regulatory effects of vasopressin during phylogenesis is discussed, as is the question of the increases in its level of involvement in the regulation of higher nervous functions and memory processes.

The role of dermorphin in the regulation of the processes of hibernation in mammals.

Data are presented in this paper regarding the influence of the opioid peptide, dermorphin, and its conjugate on the conditioned reflex activity of sousliks. The administration of dermorphin (0.1 mu/g, subcutaneously) is accompanied by a fall in body temperature, slowing of the baseline vegetative indices, and the sinking of the animal into a sleep-like state. A substantial disturbance of conditioned reflex activity was identified in the late period (delayed effects). Immunization of the hibernating sousliks with a conjugate of dermorphin leads to a gradual awakening of the animals from hibernation, to the normalization of conditioned reflex activity, and to the appearance of the motoric component of a conditioned defense reaction. The question of a possible specific role of dermorphin in the mechanisms of hibernation is discussed.

Participation of beta-endorphin in the regulation of conditioned reflex activity of cats.

The role of beta-endorphin in the regulation of conditioned instrumental food-procuring reactions and more complex forms of nervous activity such as reflexes of choice of the side of reinforcement was studied in cats. It was established that the subcutaneous injection of small doses of beta-endorphin (10 micrograms/kg, 15 x 10(-6) micrograms/kg) exerts a facilitatory nonspecialized effect on positive and negative food-procuring conditioned reflexes that has an overall adaptive character overall. The influence of the same doses of beta-endorphin on conditioned reflexes of choice is more complex in character, depending upon the initial level of conditioned reflex activity and on the typological features of the experimental animals. A possible mechanism of the influence of beta-endorphin on higher nervous activity is discussed.

Electrophysiological investigation of hypothalamo-neocortical connections in Macaca mulatta.

Functional relations between phylogenetically different parts of the hypothalamus and the neocortex were studied by the method of recording evoked potentials (EP) and evoked single unit responses in acute experiments on monkeys (Macaca mulatta). The focus of maximal activity of EP and of single unit responses was found to be in the frontal association cortex, where evoked responses with the shortest latencies were recorded. During stimulation of the posterior hypothalamus, mainly unit responses of excitatory character were recorded in the neocortex, whereas during stimulation of the lateral hypothalamus mainly unit responses of inhibitory character were recorded.