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PubMedDate not supplied

Classical conditioning of the stapedius muscle.

A delayed conditioning paradigm was employed to condition the stapedius muscle. While many previous attempts have failed using loud sound as the unconditioned stimulus(UCS), this paper presents evidence of successful conditioning of this muscle when the unconditioned stimulus was a mild electrocutaneous stimulation of the external ear canal. Using a weak tone as the conditioned stimulus, conditioned responses were readily obtained in eight of ten subjects after only 30 or fewer toneshock pairs. Temporal con ditioning was also demonstrated. A parallel is shown to exist between attempts to condition the pupillary and stapedius reflexes.

Acoustic Stimulation↗
PubMed1991

Asymmetries in classically conditioned head movements and cingulate cortex slow potentials in cats.

Presuming that conditioned head movements in the cat indicate a preference for a specific direction, asymmetries were also expected to be found in bilaterally recorded cingulate cortex slow potentials to a symmetrical tone stimulus during discriminative conditioning. Conditioned stimuli (CS, 1000 and 2500 Hz tones) were delivered through two miniature loudspeakers fitted to the head in front of both ears. The unconditioned stimulus (US) was an electrical stimulation of either the left or right lateral hypothalamus yielding, in addition to its rewarding effects, an unconditioned head turning response (UR) either to the left, right, forwards or upwards. Discrimination learning appeared as more extended and more rapid headturns and greater negativity in the cingulate cortex to the CS+ than to the CS-. The preferred conditioned behavioral response (CR) was a headturn to the left in 11 of 12 cats accompanying increased negativity in evoked slow potentials in the right cingulate cortex during the 128-324 ms period after the CS onset. No differences in the movements and in the cingulate potentials were found between the left versus right US stimulations. The results showed that regardless of the direction of the original unconditioned head movement, the direction of the CR was at the end of the training period to the left in 11 out of the 12 cats. Larger evoked slow potentials observed in the right cingulate cortex which were not present in the baseline measurements suggest a population bias between the hemispheres.

Animals↗
PubMed2002

Temporal discrimination using different feature--target intervals in classical conditioning of the rabbit's nictitating membrane response.

In a typical conditional discrimination, a target stimulus (X) is reinforced during one feature cue (A-->X+), but not during another feature cue (B-->X-). The present experiments used only a single "feature" cue (a 66-sec tone). On half of the trials, the target stimulus (a 400-msec light) was paired with the reinforcer when the feature-target interval was one duration (e.g., 5 sec). On the remaining trials, the interval was different (e.g., 45 sec), and the target stimulus was presented without the reinforcer. All the animals acquired this temporal discrimination, and subsequent testing with other feature-target intervals yielded generalization-like gradients. These results provide solid evidence that each portion of a feature cue is encoded in a distinctive fashion. Had temporal encoding not occurred, the feature cue would have been just as ambiguous a predictor of the reinforcer as was the target stimulus, and discrimination would not have been possible. The integration of real-time temporal encoding mechanisms into models of conditional discrimination is discussed.

Animals↗
PubMed1999

Pharmacological dissociation between the reinforcing, sensitizing, and response-releasing functions of reward in honeybee classical conditioning.

Reserpine depletes biogenic amines from their stores in the honeybee (Apis mellifera carnica) brain and leads to impaired appetitive conditioning using sucrose as a reinforcer. Compensatory injection of octopamine or dopamine directly into the brain restores these behavioral losses. Dopamine rescues the slowing-down effect on motor patterns, but not sensitization or conditioning. Octopamine leaves the motor patterns as well as sensitization unchanged but rescues conditioning. Specifically, octopamine rescues acquisition but not retrieval. Serotonin has no significant effect on sensitization but impairs conditioning. The authors conclude that octopamine is involved in selectively mediating the reinforcing but not the sensitizing or response-releasing function of the sucrose reward, whereas dopamine is selectively involved in the expression of the motor response.

Adrenergic Uptake Inhibitors↗
PubMed1975

[Electroencephalographic studies on classically conditioned defensive reflex and avoidance lever-pressing in the dog (author's transl)].

Six dogs with implanted cortical and subcortical electrodes were trained to press a lever to avoid electroshock to a hind leg. Intracerebral stimulation at low frequency was delivered as an "indifferent" or a "CD" tracer. Changes of EEG responses to the tracers prior to the voluntary lever-pressing or the conditioned avoidance lever-pressing were prior to the voluntary lever-pressing or the conditioned avoidance lever-pressing were examined by continuous frequency analysis. (1) Evoked potentials to the tracer stimulation were changed just before the conditioned defensive reflex, the voluntary lever-pressing and the conditioned avoidance lever-pressing, regardless of the site of the tracer stimulation. (2) The cortical and subcortical structures (Hippo, RF) seemed to be involved in the neural circuit responsible for the avoidance lever-pressing, whereas the sensorimotor cortex may be essential in the circuit for the alimentary lever-pressing. (3) The avoidance lever-pressing and the EEG response to the "CS" tracer were influenced by the internal inhibition (experimental extinction, inhibitory mechanism was discussed.

Animals↗
PubMed1991

Locus coeruleus involvement in the learning of classically conditioned bradycardia.

Opioid agonists are known to inhibit the activity of locus coeruleus (LC) neurons. In this study, microinjections of the mu-opioid agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO; 1.6 microM) bilaterally into the LC caused a significant impairment in the development of a heart-rate (HR) conditioned response (CR). The adverse effect of DAMGO on the HR CR could be reversed with naltrexone pretreatment. Microinjections of DAMGO into the periaqueductal gray, parabrachial nucleus, or fourth ventricle structures 1-2 mm away from the LC had no effects on the development of an HR CR. We conclude that central noradrenergic activity as mediated by the LC is critically involved in the learning and retention of conditioned cardiovascular responses.

Analysis of Variance↗
PubMed1988

Classically conditioned responses in opioid and cocaine dependence: a role in relapse?

We have shown that conditioned phenomena occur in a number of drug-related settings and that they can be reliably elicited and studied. Our recent work suggests that conditioned craving is an extremely prevalent, if poorly understood, response to drug-related stimuli and that it can occur independent of conditioned withdrawal responses. Our current extinction protocols are effective in reducing the conditioned responses to both opioid and cocaine-related test stimuli. How well this extinction training generalizes to the "real world," is, of course, the crucial clinical question. We are trying to maximize the generalization of extinction through use of realistic, individualized drug "reminders." The final clinical impact of these extinction procedures awaits completion of our ongoing treatment/outcome studies in abstinent opioid and cocaine abusers.

Cocaine↗
PubMed1988

Parallel pathways can conduct visual CS information during classical conditioning of the NM response.

Single and combined lesions were made to the lateral geniculate nucleus (LGN), the superficial layers of the superior colliculus (SC), and the pretectal nuclei (Ptc) prior to conditioning of the nictitating membrane (NM) response in rabbit with a visual conditioned stimulus (CS). Due to technical considerations, lesions of the dorsal LGN were accompanied by lesions of the visual cortex, the only output of the dorsal LGN, in order to render the dorsal LGN nonfunctional. Single lesions to any one of the 3 target systems (LGN, SC, Ptc) did not alter the rate of conditioning. Furthermore, double lesions to any 2 of the systems did not prevent conditioning, although LGN + SC lesions significantly retarded acquisition. When all 3 systems were lesioned, however, animals never acquired to the visual CS, although they successfully conditioned to an auditory CS. The results indicate that in rabbit there are parallel visual pathways individually capable of supporting the acquisition of conditioned NM responses.

Animals↗