Psychopharmacology and conditional reflexes

Drugs may be used in several ways to investigate their role in behavior. (1) The placebo effect is usually connected with the relation of the person to the drug. (2) Using the drug as an unconditional stimulus, its action may help to analyze the role of peripheral vs. central stimuli in the formation of conditional reflexes; our work has shown that the effect of drugs which act solely at the peripheral nerve endings without the involvement of the central nervous system cannot become conditioned. (3) The action of drugs on the conditional reflex (CR) compared with their action on the unconditional reflex (UR) explains some of their behavioral effects. (4) Schizokinesis is often prominent in the action of drugs. Although a drug may increase the level of the heart rate, for example, it can, on the other hand, diminish the reactivity shown in the CR. Meprobamate and mescaline affect differently the cardiac and the motor components of the CR, illustrating a schizokinesis. (5) The type of individual is an important factor in the action of drugs; the same drug may have opposite effects on different individuals. This leads to the conclusion that a drug should fit the individual as well as the disease. (6) Autokinesis is often seen in drug action. Therefore a single dose of some drugs, such as acetylcholine, epinephrine or LSD, may permanently change the relationships between excitation and inhibition, in the direction of improvement or deterioration (positive or negative autokinesis).     

Cerebellum and conditioned reflexes

The central assumption of existing models of motor learning in the cerebellum is that cerebellar mossy fibres signal information about the context in which a movement is to be performed and climbing fibres signal in relation to a movement error. This leads to changes in the responsiveness of Purkinje cells, which on the next occasion will generate a corrected output in a given context. Support for this view has come mainly from work on adaptation of the vestibulo-ocular reflex. The discovery that classically conditioned eyeblink responses depend critically on the cerebellum offers the possibility to study the learning of a novel behaviour, rather than modification of an existing reflex. After repeated pairing of a neutral stimulus, such as a tone, with a blink-eliciting stimulus, the tone will acquire the ability to elicit a blink on its own. We review evidence from studies employing a wide variety of techniques that the cerebellum is critical in this type of learning as well as evidence that mossy and climbing fibres have roles assigned to them in cerebellar learning models.     

The functional architecture of instrumental conditional reflexes

The author holds the opinion that the so-called operant, or instrumental, conditional reflexes, in spite of differences in specific features, do not differ in principle from classical conditional reflexes, and therefore they should not be opposed to them, or be placed in a special or separate group. In support of this opinion, this paper presents data which show that:

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   In the establishment of classical and operant conditional reflexes, two-way conditional connections—direct and reverse—are formed.     
   
   

An experimental psychophysiological approach to human bradycardic reflexes

Integrative Psychological and Behavioral Science - Bradycardic reflexes in man are both of scientific and clinical interest. Using the methods of experimental psychophysiology, control over...     

Tuning of human vestibulospinal reflexes by leg rotation

Changing the foot position modifies the mechanical action exerted by the ankle extensor and flexor muscles over the body. We verified, in two groups of healthy subjects standing with the heels touching or apart, whether a 90° external rotation of the right leg and foot also changes the pattern of vestibulospinal reflexes elicited by electrical stimulation of the labyrinth. With the head oriented forward, leg rotation did not modify the labyrinthine-driven displacements of the center of pressure (CoP). When the head was rotated in the horizontal plane, either to the right or to the left, the CoP displacement increased along the y axis in all subjects. Changes in the x component in most instances appropriate to preserve unmodified the direction of body sway elicited by the stimulus were observed. Right leg rotation increased the basal EMG activity of ankle extensors and flexors on the left side, while the right side activity was unaffected. The EMG responses to labyrinthine stimulation were modified only on the left side, in a way appropriate to correct the effects of the altered torque pattern exerted on the body by right leg muscles. It appears, therefore, that somatosensory signals related to leg rotation and/or copy of the corresponding voluntary motor commands modify the pattern of vestibulospinal reflexes and maintain the postural response appropriate to counteract a body sway in the direction inferred by labyrinthine signals.     

Some aspects of Rashevsky's theory of delayed reflexes

A closed solution of the integral equation obtained by N. Rashevsky, with the assumption that the inhibitory influence between centers is a constant, i.e., independent of the distance apart, is obtained. Furthermore, a more general kernel, representing a variable inhibitory influence, which in our case is a monotonic (increasing or decreasing) function of the distance between centers, is introduced. The resulting integral equation is solved and some properties of the solution discussed.     

The modulation of visual orienting reflexes across the lifespan

The development of reflexive and voluntary shifts of visual attention, as well as relations between the two forms of shifting, were examined in three groups of children (5, 7, and 9 years old), one group of young adults (24 years old), and two groups of senior adults (young seniors with an average age of 69 years, and old seniors with an average age of 81 years). The task entailed response to the detection of a target (black dot) in one of four possible locations in the visual field. Relations between reflexive and voluntary shifts of attention were gauged by the degree to which flash and arrow facilitation and inhibition were observed in response to the presentation of both arrow and flash cues together in one trial. All age groups oriented reflexively in response to a flash cue and utilized the arrow cue to orient attention strategically. When flash and arrow cues were presented in quick succession and thereby competed for attention, the youngest children and oldest seniors were least efficient and flexible in their approach to the orienting task as they had difficulty modulating visual reflexes.     

Post-stop-signal slowing: strategies dominate reflexes and implicit learning

Control adjustments are necessary to balance competing cognitive demands. One task that is well-suited to explore control adjustments is the stop-signal paradigm, in which subjects must balance initiation and inhibition. One common adjustment in the stop-signal paradigm is post-stop-signal slowing. Existing models of sequential adjustments in the stop-signal paradigm suggest that post-stop-signal slowing may be based solely on the events of the previous trial, suggesting that post-stop-signal slowing is a reflexive byproduct of a stop signal. Alternatively, post-stop-signal slowing could be the result of implicit learning or strategic adjustment. The authors report three experiments that manipulated the probability of stop trial repetition and found that these contingencies eliminate, reverse, or greatly increase post-stop-signal slowing. When the contingency was not instructed or cued, modest adjustments of post-stop-signal slowing occurred, suggesting implicit learning. When the contingency was cued, performance adjustments occurred on the next trial, suggesting that strategies dominated post-stop-signal slowing. These results show that post-stop-signal slowing is not a reflexive byproduct of the stop signal. The large changes in strategy accompany large changes in task factors, suggesting that the modest post-stop-signal slowing usually observed may be a result of the relatively static task environment that does not encourage large strategic changes.     

Conditional reflexes as related to hypnosis and hypnotic techniques

Hypnosis has never been adequately explained in terms of conceptual framework of most schools of psychotherapy. The psychoanalytic concept that it consists of submission and surrender of important ego functions to the therapist does not explain all observed facts. During my wartime studies and since, I have been impressed by the observation that the patient’s ego is by no means powerless and defenseless, even during a deep state of trance, i.e., in states of trance sufficiently deep to eliminate awareness of painful body injuries (1965). Erickson (1954) has shown on many occasions that in resistant subjects one of the best ways to induce trance is to encourage the patient to resist as much as he can. Haley (1963) has pointed out in detail that at the beginning of any hypnotic relationship there evolves a subtle battle for“one-upman-ship. ” These observations certainly show that surrender in the psychological sense is by no means an aspect of even the most successfully induced trance states. By contrast to these excessively simple psychotherapeutic models, Pavlovian physiology (Pavlov, 1941) explains most of the variegated phenomena of the trance and of the particular psychological set which hypnotic psychotherapy provides. Pavlov (1941) concluded from his studies in the dog that“hypnosis can be produced by the continuation of one and the same stimulus, finally resulting in an inhibitory state” (p. 75) irrespective of the nature of this stimulus. In man it is quite obvious that it is the monotony and repetitiveness of the hypnotist’s discourse and the unchanging sameness of the setting and of the position of the patient which is the most convenient way to induce trance. Also Helge Lundholm’s method (1942) of deepening hypnosis by counting is explainable by this important and simple finding of Pavlov.     

Interaction between penile reflexes and copulation in male rats

Intact, unanesthetized male rats were place in a supine position, with the penile sheath continuously retracted. Three forms of penile reflex were displayed: erections, cups, and flips. The reciprocal relation between copulation and the penile reflexes occurring in supine tests was explored in four experiments. In Experiment 1, sexual exhaustion depressed all penile reflexes, but the reflexes returned to baseline levels within 8 hr, long before copulatory potential. In Experiment 2, reflexes were depressed to exhaustion levels after fewer ejaculations than were required for sexual exhaustion, an indication that reflexes are more readily evoked during copulation than in supine tests. Experiment 3 determined that a rat's penile-reflex potential may be enhanced by placing the rat in a copulation-test cage, by allowing the male a few antecedent intromissions, or by allowing an antecedent ejaculation. The display of penile reflexes within 1 min after ejaculation suggests that the period of reduced sexual arousability following ejaculation is not due to reduced excitability in the spinal mechanisms controlling penile reflexes. In Experiment 4, 1 hr of penile-reflex elicitation had no effect on subsequent copulatory behavior. Thus, sexual stimulation may increase or decrease penile-reflex potential, but a reciprocal influence was not detectable.     

Conditional reflexes as related to hypnosis and hypnotic techniques

Hypnosis has never been adequately explained in terms of conceptual framework of most schools of psychotherapy. The psychoanalytic concept that it consists of submission and surrender of important ego functions to the therapist does not explain all observed facts. During my wartime studies and since, I have been impressed by the observation that the patient’s ego is by no means powerless and defenseless, even during a deep state of trance, i.e., in states of trance sufficiently deep to eliminate awareness of painful body injuries (1965). Erickson (1954) has shown on many occasions that in resistant subjects one of the best ways to induce trance is to encourage the patient to resist as much as he can. Haley (1963) has pointed out in detail that at the beginning of any hypnotic relationship there evolves a subtle battle for “one-upmanship.” These observations certainly show that surrender in the psychological sense is by no means an aspect of even the most successfully induced trance states.     

Acoustic startle reflexes in the rat during consummatory behavior.

Auditory startle reflexes were elicited in thirsty rats when they were drinking water or were between drinking boutsmthe reaction was greater during drinking, this enhancement developing over the first few seconds after drinking onset. The startle reaction was lowest immediately after the termination of drinking. Reflex enhancement was reduced when thirsty rats drank milk rather than the more preferred water. The reflex was smaller with increased water deprivation, but enhancement produced by drinking was apparent at all levels of deprivation studied, satiety to 4-days deprivation. The inhibitory effect of a preliminary stimulus was not affected by consummatory behavior. Attention is drawn to suggestive parallels between these behavioral effects and other consequences of consummatory activity, primarily having to do with electrophysiological events and arousal processes