Classical conditioning of hippocampal theta patterns in the rat.

Electrical stimulation (88 HZ) of the lateral hypothalamus elicited a sustained theta response at hippocampal recording sites of rats immobilized with succinylcholine. By pairing this unconditioned stimulus with a 10-sec presentation of a light, conditioned theta responses were demonstrated in as few as 40 trials. Spectral analysis of hippocampal bioelectric patterns during acquisition, extinction, and reconditioning indicated that the earliest change as a result of conditioning is a loss of power in EEG frequency below 8 HZ, followed by the development of a peak at 8 HZ with further conditioning. Extinction was associated with an increase in power in the frequencies below 8 HZ. When the conditioned rats were tested in the absence of the neuromuscular blocking agent, the conditioned stimulus elicited a theta response that was associated with slow motor activity on 70% of the trials.     

Instrumental cardiovascular conditioning: A review

This paper reviews experiments, hypotheses, and current controversies about instrumental cardiovascular conditioning. Demonstrations of such conditioning in curarized animals challenged a differentiation between instrumental and classical learning on the basis of their respective effector systems but did not prove direct operant learning by the autonomic nervous system. In humans, ethical prohibition of curarization and lack of adequate controls for respiration and muscle tension have resulted in incomplete understanding of the roles of voluntary, somatic mediators. Despite a variety of potential clinical applications of biofeedback, the available literature lacks studies of its efficacy compared to more standard modes of therapy. The physiological mechanisms and central neural pathways involved ininstrumental cardiovascular conditioning remainalmost totally unknown.     

Instrumental conditioning of aggressive behavior in rats

A method has been developed for bringing an aggressive response under stimulus control. It was found that the number of conditioned aggyessive responses was maximal when low-weight target rats were used. The latencies of the conditioned responses toward target animals of 124 gm were significantly lower than those toward animals of 221 and 284 gm. The application of an extinction procedure on the conditioned aggressive response substantially increased the total number of emitted aggressive responses.     

Reading the hippocampal code by theta phase-locking

Both the prefrontal cortex and the hippocampus are crucial for memory encoding and recall. However, it remains unclear how these brain regions communicate to exchange information. Recent findings using simultaneous recordings from the hippocampus and prefrontal cortex of the behaving rat have demonstrated that prefrontal cells' firing is phase-locked to the hippocampal theta rhythm. This suggests that phase synchronization clocked by the theta rhythm could be crucial for the communication between hippocampal and prefrontal regions.     

Instrumental conditioning of scratching in the laboratory rat

Experiment 1 demonstrates that scratching in the laboratory rat can be instrumentally conditioned with food reinforcement. However, the asymptotic rate of performance of this response is shown to be low, as compared with an instrumental lever press response. It is suggested that one reason for this low rate of responding is that the scratch response can only be performed in the presence of an infrequently occurring itch stimulus. In support of this account the remaining experiments demonstrate that the rate of instrumental scratching can be increased relative to that shown by control groups by using a technique which might be supposed to increase the frequency at which an itch stimulus occurs.     

Instrumental conditioning of blood pressure elevations in the baboon

Two adult male baboons were surgically prepared with arterial catheters which provided a continuous measure of blood pressure and heart rate. Environmental consequences (food and electric shock) were made contingent upon prespecified increases in diastolic blood pressure levels. Continued exposure to these contingencies resulted in substantial increases in both diastolic and systolic pressures. The results demonstrated that blood pressure changes are highly susceptible to both operant“shaping” and stimulus control procedures and extend the range of instrumental conditioning effects upon the cardiovascular system.     

Instrumental conditioning of diastolic blood pressure in essential hypertensive patients

Eighteen male essential hypertensive patients participated in an experiment designed to compare two strategies for controlling high blood pressure. Each strategy was derived from the instrumental learning literature, and the aim was to treat the blood pressure response as an operant and determine the most effective conditioning procedure for manipulating it. The results demonstrate that patients could be conditioned to lower blood pressure by 20% to 30% over a period as brief as four days by providing an external signal and verbal praise contingent upon each reduction in diastolic pressure that met a pre-set criterion.     

Immobility-related hippocampal theta activity in rats during reaction to novelty

Two types of theta activity are seen in the hippocampal formation of the rat. Type 1 theta which has a high overall frequency is related to movements, whereas Type 2 theta of lower frequency is related to immobility. The purpose of the present study was to investigate whether Type 2 theta may occur in rats encountering novelty. To shed light on this issue rats were tested in a novelty test in which smell made up the novel aspect. Upon encountering a cheese spot on the novel object the rats displayed relatively high-frequency theta activity while all legs were immobile, and low level of EMG activity was seen in the nuchal muscle. It was not possible to test whether the "novelty theta" was sensitive to atropine, since administration of atropine sulphate abolished the rats' preference for novelty. The results are discussed in terms of Type 2 theta reflecting sensory processing.