Overnight Performance Decrement with Intracranial Reinforcement

Abstract

An overnight performance decrement is allegedly characteristic of habits maintained by intracranial electrical stimulation. The decrement was here found to be (a) not common to all electrode sites, (b) reduced by one un-reinforced trial, and (c) reduced by intracranial stimulation administered below a rewarding intensity. The electrode sites not associated with performance decrement were in the median forebrain bundle (MFB). Those associated with decrement were somewhat removed from the MFB, at sites other experiments have shown to be both positively and negatively reinforcing. These findings are discussed in relation to Deutsch's theory of simultaneous drive-induction and reinforcement.

Intracranial stimulation: Performance decrements and a fear-reducing drug

“…Data from our previous studies (Wasden, Reid, & Porter, 1965;Wasden, 1966) have conflicted with both of these explanations. Importantly, not all of the rats we have tested have shown a discrete-trial performance decrement, even following a lO-day intertrial interval.…”

“…It might be assumed that some real confusion of associational processes occurs as a result of stimulation in reinforcing areas. The emotion or motivation engendered by appetitive or aversive ICS results in a disruption of mnemonic processes or obscures an intact mnemonic mechanism.Data from our previous studies (Wasden, Reid, & Porter, 1965;Wasden, 1966) have conflicted with both of these explanations. Importantly, not all of the rats we have tested have shown a discrete-trial performance decrement, even following a lO-day intertrial interval.…”

“…However, the data do support the notion that the lCS decrement results from an approach-avoidance conflict. lCS reinforcement does not always result in performance decrements (Wasden, Reid, & Porter, 1965), but in those instances in which it does, some fear-inducing component of the electrical stimulation appears to playa causal role.…”

Extinction after water and intracranial reinforcement

“…That is, they run slowly, or not at all, on the first trial, but may run quite fast on subsequent trials after receiving reinforcement. The former type of 8 has been referred to as nondecrement (lCR-N) and the latter as overnight (or over intersession interval) decrement (ICR-D) (Wasden, Reid, & Porter, 1965). It is possible that some of the differences between conventional and ICR Ss predicted by Deutsch's theory are due to the use of only, say, decrement 8s.…”

Reinforcing limbic system stimulation and sodium amytal

“…Some Ss show an overnight or between-trials performance decrement of varying degrees, and others show little or no decrement in performance no matter when (at least, up to 10 days) the last ICS was given (Wasden, Reid, & Porter, 1965). The phenomenon of discrete-trial performance decrement has played a central role in the formulations ofDeutsch (Deutsch & Deutsch, 1966) and is important because it is one of the limiting features of ICS as a reinforcer.…”