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).     

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.     

The treatment of childhood encopresis by conditioned gastro-ileal reflex training

The indications for conditioned gastro-ileal reflex training are discussed and the method of treatment for childhood encopresis is described. Twenty-four children were treated by this method. Nineteen were successfully treated in less than 1 year (mean = 5 months), three were successfully treated in more than 1 year (mean = 17 months) and two children made no response. During a follow-up period ranging from 6 months to 6 years (mean = 29 months) the symptom had recurred in 4 children.     

Syntax as a reflex: neurophysiological evidence for early automaticity of grammatical processing

It has been a matter of debate whether the specifically human capacity to process syntactic information draws on attentional resources or is automatic. To address this issue, we recorded neurophysiological indicators of syntactic processing to spoken sentences while subjects were distracted to different degrees from language processing. Subjects were either passively distracted, by watching a silent video film, or their attention was actively streamed away from the language input by performing a demanding acoustic signal detection task. An early index of syntactic violations, the syntactic Mismatch Negativity (sMMN), distinguished between grammatical and ungrammatical speech even under strongest distraction. The magnitude of the early sMMN (at <150ms) was unaffected by attention load of the distraction task. The independence of the early syntactic brain response of attentional distraction provides neurophysiological evidence for the automaticity of syntax and for its autonomy from other attention-demanding processes, including acoustic stimulus discrimination. The first attentional modulation of syntactic brain responses became manifest at a later stage, at approximately 200ms, thus demonstrating the narrowness of the early time window of syntactic autonomy. We discuss these results in the light of modular and interactive theories of cognitive processing and draw inferences on the automaticity of both the cognitive MMN response and certain grammar processes in general.     

The place of the conditioned reflex in psychology and psychiatry: Reply to reese,dykman, and peters

Razran’s “The Place of the Conditional Reflex in Psychology and Psychiatry” delivered at GAP Symposium No. 9 traced historically the influence of Russian physiology on American behavior systems, first in the classical Watson period and then in present-day Neobehaviorism. The address collated Pavlovianism and Behaviorism, and mentioned recent Soviet emphasis of interoceptive, semantic, and compound-stimulus conditioning. Within the limits of time, it dealt with group developments and not with individual contributions. And it assumed that a behavior system comprises both normal and abnormal aspects; that is, the basics of both psychology and psychiatry. The assertion by Reese, Dykman and Peters that “Psychiatrists tend to avoid contributions of experimental psychologists and vice versa” is not shared by Razran, nor, he believes, by American psychiatry and experimental psychology as such. And the assertion is contrary to the Pavlovian tradition. Pavlov’s first, 1903, publication on conditioned reflexes was entitled “Experimental Psychology and Psychopathology in Animals” which he later renamed “the physiology and pathology [or pathophysiology] of higher nervous activity.”     

Odor as a conditioned inhibitor: Applicability of the Rescorla-Wagner model to feeding behavior

Hooded rats were given conditioned inhibition training in which the taste of saccharin alone was always followed by induced illness, but the taste of saccharin plus the odor of amyl acetate was not. In a series of three subsequent tests—summation, enhancement of conditioning, and retardation—it was demonstrated that the odor had acquired active inhibitory properties. The results paralleled those obtained with more traditionally studied stimuli and techniques and hence were found to be readily predictable from a recent model of conditioning set forth by Rescorla and Wagner (1972).