BRAIN STIMULATION AS A REINFORCER: INTERMITTENT SCHEDULES¹

Abstract

Rats with chronically implanted, bipolar electrodes in the septal and medial forebrain bundle areas, in addition to the region of the mammillary bodies of the posterior hypothalamus, were trained to press a permanently mounted lever in order to produce a second, retractable lever. Rewarding brain stimulation was programmed on the retractable lever; following completion of the programmed number of CRF response-stimulations, that lever was retracted from the box. Responding on the permanent lever could reintroduce the retractable lever. Fixed interval, fixed ratio, DRL, and variable interval schedules were programmed on the permanent lever in the range of schedule parameters often used with conventional reinforcers. Typical effects are described, and it is concluded that there are no striking differences between brain-stimulation reinforcement and the conventional reinforcers.It is well-known that electrical stimulation of certain subcortical braiin sites can serve as a reinforcer. Much of the research on brainstimulation reinforcement (BSR) over the past 10 years or so has been concerned with (a) the mapping of various loci which produce reinforcing effects when stimulated, (b) the analysis of brain-stimulation phenomena, and (c) theoretical attempts to integrate many of the research findings. Olds (1962) Brady and Conrad (1960b), viz., a 60-sec variable interval schedule and by Brady and Conrad (1960a), viz., a DRL of 20 sec. Brodie, Moreno, Malis, and Boren (1960) obtained a fixed ratio performance of 150 responses in one of 11 monkeys. Also, Boren and Malis (1961) reported an adjusting avoidance schedule employing an electrode placement at which stimulation was aversive.Conspicuously absent from the BSR literature have been experimental reports describing behaviors maintained by intermittent schedules of BSR in the range of parameter values ordinarily used with food as a reinforcer. The lore of BSR research teaches that intermittent schedule performances are difficult to maintain. It is hard to estimate the degree to which that lore is the result of research on intermittent schedules, since "negative" results tend not to be published, and the degree to which its acceptance has discouraged such research. Following a lead from our laboratory , it was decided to examine intermittent schedule performances employing a chaining procedure in which the first chain member is traditional self-stimulation (CRF, but with a fixed number of stimulation-reinforced responses) and the second chain member is an intermittent reinforcement schedule. There was reason to 75 VOLUME 8, NUMBER 2 MARCH, 1965

Successive sensory discriminative behavior maintained by forebrain self-stimulation reinforcement

“…Furthermore, priming was not necessary to start the animals responding to the S+ at the beginning of the daily sessions, and the animals displayed an unexpectedly high resistance to extinction. This study and many others in recent years (Gandelman, Panksepp, & Trowill, 1968;Gibson, Reid, Sokai, & Porter, 1965;Kornblith & Olds, 1968;Lenzer & Frommer, 1968;Pliskoff, Wright, & Hawkins, 1965;Scott, 1967;Trowill, Panksepp, & Gandelman, 1969) indicate that lability, defined as the relatively rapid decline in response strength during periods when reinforcement is not obtainable, is not a general or unalterable property of behaviors maintained by ESB reinforcement; thus, the drive-induction and -decay theory proposed by Deutsch and others (Deutsch & Howarth, 1963;Gallistel, 1964;Howarth & Deutsch, 1962)is called into question. Trowill et al (1969) maintain that the paradoxical lability of ESB-reinforced behaviors sterns from training procedures and not from any inherent features of ESB reinforcement.…”

Reinforcer and response specificity in appetitive transfer of control

“…However, it can be argued (cf. Hawkins & Pliskoff, 1964;Pliskoff, Wright, & Hawkins, 1965) that this requirement in fact makes conditioning with ESB more similar to conditioning with conventional reinforcers. That is, barpressing for ESa is analogous to the normal consummatory responses necessary with a food or water US.…”

Brain Stimulation Reinforcement: Implications of an Electrode Artifact

“…Furthermore, without the artifact making the signal an SD in a chain schedule, the signaling procedure is as poor as or worse than simple response-contingent BSR (7) in bringing about lever pressing on an intermittent schedule. The efficacy of a chain schedule in establishing schedule performance with BSR was first shown (5,8). Only evidence (with cumulative records) of such schedule performance should be taken in support of the assertion that chaining is unnecessary.…”