The effects of scopolamine upon classical indices of activation have been equivocal. BRA])L]~u and ELK,S (1957), MEu et al. (1964); and WrKLER (1952), among others, have reported clectrocncephalographic (EEG) activity resembling that of sleep following injections of this drug. Paradoxically, however, have been the findings suggesting concomitant behavioral activation under this agent. Indeed, following an extensive survey of the anticholinergic behavioral literature, CA~L~O~r (1963) concluded that scopolamine β’ HBr (and certain other centrally-acting cholincrgic antagonists) served to degrade the inhibiting effects of the cholinergic system on a second activation system, the net effect being to energize behavior.
Unfortunately, with one exception, most behavioral studies designed to assess scopolamine-produced inhibitory release on the so-called activation system have involved substantially indirect testing procedures. That is, increases in arousal typically have been indirectly inferred from behavior derived from complex test procedures which have involved disruptions of established indicant responses as their reference measure. As MEY~s et al. (1964) have implied, however, a more direct behavioral assessment might involve simply plotting activity changes subsequent to drug injections. Experiment 1 was designed to extend and elaborate their prelirniuary findings.
Experiment I Methods
Twelve, naive, male, albino rats, and 15 naive, male, hooded rats, all 100--120 days of age and from the same supplier (Simonson Farms, California), were employed. All Ss were maintained on an ad lib food