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R M Stutz

Publications and source records attributed to R M Stutz.

At least 19 recordsLinked to original sources
PubMed1984

Self-deprivation: a test of the reward hypothesis.

Self-deprivation refers to the observation that despite severe levels of water and food deprivation some rats dramatically reduce food and water intake when brain stimulation reward and the alternative reward are placed in competition. In order to determine if the rewarding properties of brain stimulation are responsible for self-deprivation, rats were implanted bilaterally with stimulating electrodes and subsequently tested for self-deprivation and preferences among various electrode locus/stimulation current combinations. According to the reward hypothesis, the relative degree of self-deprivation observed for each electrode/current pair should predict the order of preference for each combination when different electrode/current pairs are placed in competition. Likewise, across all combinations of electrodes and intensities, increasing preferences should be associated with increasing self-deprivation. The findings of the study provide support for the reward hypothesis of self-deprivation. The correlation between the self-deprivation and the preference measure was r = 0.62 (p less than 0.001), which rose to r = 0.80 (p less than 0.001) when floor and ceiling effects were taken into account. It was concluded that the rewarding aspects of brain stimulation are responsible for the self-deprivation phenomenon.

Animals↗
PubMed1984

Subject control as a determinant of the reinforcing properties of intracranial stimulation.

There has been some controversy whether experimenter-administered electrical stimulation of the brain is aversive or simply less reinforcing than that delivered via self-stimulation. Rats with MFB-LH electrodes self-stimulated with high, medium, and low currents and the self-produced rates were tape recorded. In Experiment 1, the rats were allowed to choose between self-administered versus replayed ESB. When both types of stimulation were available at medium intensities, the rats preferred to self-administer the ESB. This preference was increased when the re-played stimulation was presented at a lower intensity than the self-administered ESB. However, the preference for contingent ESB decreased when the intensity of the experimenter administered ESB was increased suggesting that experimenter-administered ESB is not aversive. In Experiment 2, the rats chose between experimenter administered ESB delivered at the played-back self-generated rate versus a regular averaged rate. All Ss preferred the previously self-generated mode. In Experiment 3, the rats were deprived of water and given four daily competition tests between experimenter administered ESB versus water. All rats "self-dehydrated" again demonstrating that experimenter-administered ESB is not aversive. It is concluded that rats prefer to control the rate at which ESB is presented, but that non-contingent stimulation is clearly not aversive.

Animals↗
PubMed1984

The role of brain stimulation priming effects in self-deprivation.

Choice of brain stimulation reward (BSR) over biologically necessary substances in some self-stimulating animals is referred to as self-deprivation. In several recent papers, it has been argued that this phenomenon is produced by the rewarding aspects of the brain stimulation. This conclusion is partially based on data showing that self-deprivation and brain stimulation reward increase and decrease in a similar manner in response to changes in the brain stimulation parameters. However, the priming aspects of the brain stimulation also fluctuate with changes in stimulation parameters. Therefore, changes in the priming rather than the rewarding aspects of the brain stimulation could be responsible for self-deprivation. To determine whether the priming effects of brain stimulation play an important role in self-deprivation, rats with bipolar stimulating electrodes were given the choice between BSR and food. Time-outs were enforced within each BSR/food competition session. Since priming effects decay over time, increasing time-out length should have decreased self-deprivation due to decay of priming. It was found that time-out length did not affect the degree of self-deprivation. It was concluded that self-deprivation is not mediated by the priming aspects of brain stimulation.

Animals↗
PubMed1982

Lateral hypothalamic stimulation: stimulus-bound eating and self-deprivation.

Research was undertaken in an attempt to clarify the relationship between stimulus-bound eating and self-deprivation produced by electrical stimulation of the lateral hypothalamus. It was hypothesized that if these two phenomena are mediated through a common population of feeding-related neurons, a significant correlation should be observed between these two behaviors. No significant relationship was discovered among the rats tested for both stimulus-bound eating and self-deprivation. Although this finding by itself does not rule out some role for feeding-related neural elements in stimulus-bound eating and self-deprivation, the present results provide no support for this view and suggest alternative explanations should be sought.

Animals↗
PubMed1982

Effects of parenteral morphine and oral methadone on self-stimulation in the rat.

Facilitation of self-stimulation has been reported following the administration of various opiates. Methadone, a synthetic narcotic used in the treatment of narcotic addiction, has recently been demonstrated to facilitate self-stimulation when administered parenterally. The present study examined the effects of orally administered methadone (20 and 30 mg/kg), the route of administration used clinically, on MFB-LH self-stimulation at 2.5, 5, 8, 12, 17, and 24 hours post-administration. Reliable facilitation was observed at 2.5 hours post-administration. However, the effect of methadone was less pronounced than that observed with a dose of parenteral morphine which was approximately equivalent in terms of analgesic potency.

Administration, Oral↗
PubMed1980

Facilitation of self-stimulation in rats by methadone.

The effects of morphine and its derivatives on self-stimulation behavior have been widely studied. In those experiments which have used multiple injections (over days) and multiple post-injection tests (within days), the typical findings includes a depression of responding after the initial injections followed by a facilitation of responding on subsequent days. There have been only a few reports which have tested the effects of methadone in this paradigm. Some investigators have observed only depression of self-stimulation while others have reported both the transient depression and the subsequent facilitation generally obtained with morphine. In the present experiment we administered either 5 mg/kg or 10 mg/kg methadone IP over a five day period and tested MFB-LH self-stimulation at 2, 4, 6, 8, 10 and 23 hours post-injection. Compared to saline controls, the 10 mg/kg dose produced the typical opiate-induced changes in self-stimulation, i.e., an initial depression which lasted for two hours on the first two days but was replaced by significant facilitation by hour 4 of day 3. This facilitation persisted for at least 10 hours on all 5 days of the experiment. Except for a transient (days 2-3) depression of self-stimulation, 5 mg/kg was without effects. The present experiment demonstrates that methadone does facilitate self-stimulation but that its ability to do so is highly dose-dependent.

Animals↗
PubMed1978

Morphine and self-stimulation: evidence for action on a common neural substrate.

Recent studies have demonstrated that the self-stimulation phenomenon may provide a useful technique for investigating the rewarding properties of potentially addictive drugs such as morphine. The present study attempted to examine the nature of morphine's effects on self-stimulation by observing changes in rate-intensity functions following morphine administration. The results indicate that morphine markedly enhanced bar pressing for low intensity stimulation when the intensities were presented in an ascending sequence but morphine produced only slight changes in self-stimulation rates when a descending series was used. The failure of morphine to facilitate responding in the descending series suggests that adaptation of the self-stimulation system can block morphine's effects on this system. These findings appear to support the hypothesis that morphine affects the excitability of the neural system which mediates self-stimulation.

Animals↗
PubMed1969

Stimulus properties of reinforcing brain shock.

Rats easily discriminate between two types of subcortical brain shock which differ in reinforcing properties. When both stimuli are either neutral or positively reinforcing subjects have difficulty in responding differentially to the two types of electrical stimulation of the brain. Possible implications for a theory concerning a generalized or diffuse reinforcement system are discussed.

Analysis of Variance↗