Kupalov's concept of shortened conditional reflexes: psychophysiological and psychopharmacological implications.

In the regulation of cortical excitability tonus, Kupalov described a particular acquired, learned mechanism, the shortened conditional Reflex (SCR). SCR is an essential mechanism by which an adequate cortical tonus is established by environmental cues as an anticipatory set-up preparing the individual qualitatively and quantitatively for expected forthcoming events. An original physiological example is given, the conditional "transfer" of motor behavior at cortical electrical stimulation. Three psychopharmacological implications are presented, namely environmental-dependent, stress-related events, environmental-dependent drug conditioning, and drug-tolerance experiments. Future eventual psychophysiological and psychopharmacological lines of research related to the shortened conditional reflex concept are discussed.

Nootropic drugs and aging.

Nootropics are drugs which ameliorate the functional "plasticity" of the central nervous system. The nootropic drug acts at the telencephalic level through a series of bioenergetic, hemorheological, microcirculatory and neurochemical mechanisms. As to this, recent data show a facilitation by piracetam, of the efficiency of the central cholinergic system.

Piracetam facilitates retrieval but does not impair extinction of bar-pressing in rats.

Rats were trained on a continuously reinforced bar-press response for water reward. Seven days later they were retested for retention, with or without pretest injection of the nootropic drug, piracetam. Drug-treated animals had significantly shorter response latencies than saline-treated animals. The results are interpreted as a facilitation of retrieval processes after forgetting. The experiment was extended under extinction conditions and it was found that after three sessions there was a tendency to facilitate extinction when response latency is used as the extinction index. The clinical interest of a drug which facilitates the retrieval aspect of the memory process without impairing extinction is discussed.