Human patellar reflex and conditioned reflex compared electromyographically

Inspite of continued work on the stretch reflex and “voluntary” movement study of the conditioned stretch reflex declined early in this century. The present experiments surveyed seven classical conditioning regimens for the human rectus femoris EMG seen after a blow to the patellar tendon. It was possible to (1) rule out conditioning to a knee touch that occured together with the tap, (2) establish weak conditioned stimulus, Sc, control for a tape recorder click and subsequent fist clench that preceded the tap by variable elapsed times, and (3) establish strong Sc control for a tone that sounded an invariant 0.27 sec before the tap. There were large differences, however, in Sc power across subjects, as measured by amplitude, latency, and frequency of conditioned EMG activity that occured prior to tap or when the tap was omitted. Purely reflexive responses, especially later EMG segments, also varied in amplitude and frequency, to support a conclusion that numerous controlling stimuli added or competed from trial to trial. Further disclosure of Sc contributions, including those from movement-generated stimulation, is warranted, especially for behaviors whose rhythmic timings, as in locomotion, might favor Pavlovian conditioning.     

Modulation of a discrete Pavlovian conditioned reflex by a putative emotive Pavlovian conditioned stimulus

Three experiments showed the modulation of a rabbit eyeblink conditioned response (CR) to a Pavlovian conditioned stimulus (CS) by 30-s stimuli (A & B) that had been differentially paired with paraorbital shock. The CS (Y) was a 1,050-ms cue that had been paired with paraorbital shock outside A or B. In testing, the amplitude of CRs was greater when Y was presented within A than within B. Differential modulation occurred whether shock in A had been preceded by another 1,050-ms cue, X(AX+,BX-;Experiment 1) or not (A+B-;Experiment 2). Experiment 3 compared the technique of Experiment 1 (AX+) with that of Experiment 2 (A+) and found the latter to be advantageous for facilitation of CRs to Y by A. These data are consistent with the predictions of a model of Pavlovian conditioning (AESOP, Wagner & Brandon, 1989) that distinguishes between emotive and sensory conditioning as did Konorski (1967).     

Behaviour therapy and encopresis: The complexities involved in treatment

This paper reports the treatment of continuous encopresis in an adolescent boy. The importance of careful analysis of the symptom; the selection of an appropriate method of treatment for a particular patient; and the complications which may arise during the course of treatment are discussed.     

Toilet training,cueing, praise,and self-cleaning in the treatment of classroom encopresis: A case study

This study was designed to ameliorate encopresis in a 6-year-old male child in the school setting. The procedure consisted of toilet training, cueing, praise, and self-cleaning. Prior to intervention, encopresis was a daily event at home and school. The intervention was successful in reducing the soiling to near zero at school, with no reported changes at home. Implications discussed for school psychologists were: (a) handling the intervention through a consultation model, (b) using the simplest approach before attempting more powerful procedures, and (c) attempting treatment in spite of the fact that other treatment attempts at home had been unsuccessful.     

Retention of a classically conditioned reflex response in spinal cat

Retention of classically conditioned flexion reflex facilitation was examined in unanesthetized, decerebrate, acute spinal cats. Flexion reflex facilitation, recorded from the tibialis anterior muscle, was obtained by pairing saphenous nerve stimulation (the conditioned stimulus) with superficial peroneal nerve stimulation (the unconditioned stimulus). The flexion reflex declined in control animals receiving the same number of nerve stimuli over the same time span, but in an explicitly unpaired sequence. To investigate retention, conditioned stimuli were presented at 5-min intervals following acquisition for a 2 1/2-h period. During this time a significant difference between conditioning and control groups was maintained even to the last trial, with no indication that the difference was subsiding over time. The results support the possibility that a classical conditioning paradigm applied to the spinal cord can induce alterations in spinal reflexes of long duration. Furthermore, the results appear to rule out post-tetanic potentiation as a mechanism producing the observed long-term effects.     

A note on reflex sensitivity and formation of conditioned responses

The relationship between ease of conditioning and reflex sensitivity was examined in the GSR and blink reflex under two experimental conditions. Significant positive correlations were obtained between a variety of response characteristics (e.g. frequency, amplitude of blink, spontaneous GSRs) and the number of conditioned responses, thus supporting earlier findings obtained on different reflex measures.

Various anatomical and physiological factors which may influence reflex sensitivity are indicated, and the need to analyse these factors is stressed, especially in the context of those theories which postulate a general factor of conditionability.     

Generalization of conditioned suppression after differential training

In a modified conditioned suppression procedure, clicks at one frequency (danger signal) preceded shocks, while no shocks followed clicks at a different frequency (safe signal). During generalization tests, the maximal response rate was frequently shifted from the safe signal in the direction away from the danger signal, and the minimal response rate was frequently shifted in the opposite direction, away from the safe signal. There was considerable variability in the results from one animal to another. The generalization tests also suggested different generalization functions according to whether the danger signal was a lower or a higher frequency than the safe signal. The results also showed the development of systematic differences in response rate during and after the safe and danger signals, notably a relatively high rate at the beginning of the safe signal and after the danger signal.     

A multidisciplinary treatment for encopresis in children with developmental disabilities

Achieving continence of one's bowel movements is a key step in development and failure to do so leads to many negative consequences. Treatments for encopresis appearing in the literature have employed behavioral strategies; medications such as suppositories, laxatives, or enemas; and in some studies a combination of these approaches. To date, attempts to extend successful treatments for encopresis in typically developing children to those with developmental disabilities have been limited. The current study included three participants diagnosed with developmental disabilities who had a history of encopresis. None of the participants had a continent bowel movement under baseline conditions. Continent bowel movements increased during treatment that included the addition of suppositories to elicit continent bowel movements. Two participants began having independent continent bowel movements (i.e., without requiring suppositories) and medication was successfully faded out for the remaining participant. Treatment took between 13 and 21 days.     

Counteraction between two kinds of conditioned inhibition training

In a Pavlovian fear-conditioning preparation, we investigated the effects of combining Pavlovian and explicitly unpaired inhibition treatments. A summation test for inhibition suggested a strong tendency toward unpaired inhibition when that treatment was administered alone and found robust Pavlovian inhibition when that treatment was administered alone, but detected little behavior indicative of inhibition in subjects that experienced both treatments during training. The retardation test showed reliable unpaired and Pavlovian inhibition when these treatments were administered alone but no indication of inhibition in subjects that experienced both treatments. These counterintuitive results suggest that in some circumstances the effects of two inhibitory treatments are not additive but rather counteractive. The present results provide some information about the nature of conditioned inhibition and, more generally, cue interaction.     

Enhancement of Pavlovian conditioned inhibition achieved by posttraining inflation of the training excitor

In two conditioned lick suppression experiments using water-deprived rats, we examined the effects of following Pavlovian conditioned inhibition training (i.e., A–US/AX-NoUS) with pairings of the training excitor (A) and the unconditioned stimulus (US). Experiments 1 and 2 assessed the effects of this posttraining inflation treatment on Pavlovian conditioned inhibition using a summation test and a retardation test, respectively. Both experiments revealed that subjects exposed to inflation treatment demonstrated behavior indicative of enhanced conditioned inhibition compared to subjects that did not receive inflation treatment. The results in conjunction with other recent findings suggest that posttraining associative deflation (i.e., extinction of A) and inflation effects are more symmetrical than has previously been realized.