Orienting reflex: "targeting reaction" and "searchlight of attention"

The concept of orienting reflex based on the principle of vector coding of cognitive and executive processes is proposed. The orienting reflex to non-signal and signal stimuli is a set of orienting reactions: motor, autonomic, neuronal, and subjective emphasizing new and significant stimuli. Two basic mechanisms can be identified within the orienting reflex: a "targeting reaction" and a "searchlight of attention". In the visual system the first one consists in a foveation of a target stimulus. The foveation is performed with participation of premotor neurons excited by saccadic command neurons of the superior colliculi. The "searchlight of attention" is based on the resonance of gamma-oscillations in the reticular thalamus selectively enhancing responses of cortical neurons (involuntary attention). The novelty signal is generated in novelty neurons of the hippocampus, which are selectively tuned to a repeatedly presented standard stimulus. The selective tuning is caused by the depression of plastic synapses representing a "neuronal model" of the standard stimulus. A mismatch of the novel stimulus with the established neuronal model gives rise to a "novelty signal" enhancing the novel input. The novelty signal inhibits current conditioned reflexes (external inhibition) contributing to redirecting the behavior. By triggering the expression of early genes the novelty signal initiates the formation of the long-term memory connected with neoneurogenesis.     

Development of brain networks for orienting to novelty

Among the many contributions of I.P. Pavlov to the study of the higher nervous system was his exploration of the physical basis of attention. Pavlov's analysis of the orienting reflex (OR), together with the contributions of Y.N. Sokolov, demonstrated that attention could be studies by the objective methods of neurophysiology. Cognitive neuroscience has continued these effort by using neuroimaging to explore the anatomy and physiology of attention in the working human brain. It is now possible to show that the appearance of a novel visual event invokes multiple attentional networks that work in concert to orient to and process a novel object within a very brief exposure. In this paper, we describe cognitive studies of orienting to novelty in adults, examine the networks of neural areas involved in processing novel objects, and review the development in early life of these attentional networks. Orienting to novelty provides an excellent vehicle for examining how biology and experience shape the mechanisms of self-regulation and cognitive control.     

A comparative analysis of the conditional reflex discoveries of Pavlov and Twitmyer, and the birth of a paradigm

Research on conditional reflex (CR) in Pavlov's Physiological Laboratory has preceded Twitmyer's work on conditioning at the University of Pennsylvania by 3 or 4 years. The events in Pavlov's laboratory lead toward the postulation of a new paradigm that rejected the Cartesians conceptualization of the reflex as a mechanistic response to stimuli by replacing it with the Darwinian notion of the organism's adaptation to the environmental conditions. The Pavlovian paradigm rejected the Wundtian method in favor of the objective, conditional reflex method.     

Changes in the electrical activity of the hippocampus during elaboration of an inhibitory reaction in the dog

A conditioned alimentary instrumental reflex was elaborated in three dogs with chronically implanted electrodes to a consecutive complex conditioned stimulus consisting of two equal acoustic stimuli separated by a pause. At first, the animals reacted with motor reactions during the whole action of the complex signal. Then inhibition of reaction was elaborated at first in pause and then in response to the preparatory stimulus. In the process of stabilization of inhibition, there was an increase of similarity of spectral composition of hippocampal theta-rhythm with the values obtained in the inter-signal period. Conclusion is made that the hippocampus is not a structure necessary for the elaboration of internal inhibition. The frequency of hippocampal theta-rhythm may serve as a characteristic of the property called in Pavlov's school mobility of the nervous system.     

Pavlov as a psychologist. A reappraisal

American psychologists are informed on Pavlov's work on conditional reflexes but not on the full development of his theory of higher nervous activity. This article shows that Pavlov's theory of higher nervous activity dealt with concepts that concerned contemporary psychologists. Pavlov used the conditioning of the salivary reflex for methodological purposes. Pavlov's theory of higher nervous activity encompassed overt behavior, neural processes, and the conscious experience. The strong Darwinian element of Pavlov's theory, with its stress on the higher organisms' adaptation, is described. With regard to learning, Pavlov, at the end of his scholarly career, proposed that although all learning involves the formation of associations, the organism's adaptation to the environment is established through conditioning, but the accumulation of knowledge is established by trial and error.     

Heart rate deceleration is not an orienting reflex; heart rate acceleration is not a defensive reflex

Graham and Clifton (1966) proposed an integration of Sokolov's theory of orienting and defensive reflexes with the stimulus intake/rejection dichotomy of the Laceys. This integration consisted of hypothesizing that heart rate deceleration is a measure of the orienting reflex, and that cardiac acceleration is a measure of the defensive reflex. This article demonstrates that Graham and Clifton failed to establish a valid integration of these two theories. This failure is a consequence of 1) their misconstruing Sokolov's theory, and 2) an inaccurate and selective review of the research literature then available. Consideration of more recent research would seem to rule out the possibility that their thesis was correct in spite of these flaws in its derivation. Cardiac responding in the OR context thus remains open to further investigation and interpretation.     

The discovery of the principles of reinforcement, extinction, generalization, and differentiation of conditional reflexes in Pavlov's laboratories

The discovery of reinforcement, extinction, generalization, and differentiation with the conditional reflex method in Pavlov's laboratories is described. Modern American introductory texts show that contemporary understanding of the experimental work on conditioning in Pavlov's laboratories is derived from a 1927 English translation of Pavlov's lectures on the conditional reflexes. The lectures present the discoveries topically, not chronologically. In contrast, this article presents a chronological account of the contributions of S.G. Vul'fson, I.F. Tolochinov, and B.P. Babkin, which led to the conceptualization of reinforcement and extinction, and the work of V.N. Boldyrev and N.A. Kashereninova, which led to the formulation of the concepts of generalization and differentiation. This historical approach avoids giving the impression that the development of the Pavlovian paradigm was a highly systematic pursuit.     

I. P. Pavlov and K. Lorenz

In the thirtieth, the founder of ethology Austrian zoologist Konrad Lorenz put forward the new theory of behavior, which was met with considerable resistance of the dominant views on the mechanisms of behavior, including Pavlov's concept. From his first theoretical works and later on Lorenz debated with Pavlov. However, these debates were not reduced to a disagreement. He appreciated greatly the scientific contribution of Pavlov, and the ideas of the Russian physiologist were often the starting point of his own speculations. His polemics with Pavlov differed very much from his uncompromising controversies with behaviorists. When Lorenz compared Pavlov's views with behaviorism, he often preferred Pavlov's ideas. Lorenz also draw some parallels between the Pavlov's understanding of behavior and the ethological approach. Lorenz's discussion with Pavlov about the nature of conditioned reflex is of particular interest, since it stimulated Lorenz to develop the theory of this phenomenon.     

The role of trace excitatory processes in the formation of conditioned reflexes to time]

I. P. Pavlov's hypothesis on the role of trace excitation in conditioning to time was verified by mathematical methods proceeding from experimental data on elaborating in rabbits a motor alimentary conditioned reflex to a four-minute interval of time. A connection has been established between the experimental characteristics of formation of a reflex to time and some parameters of the presumed dynamics of trace excitation. The analysis helped to establish the shortest and longest intervals to which a reflex to time can be elaborated by the mechanism of trace reflex, as well as the optimal interval to which it is elaborated more easily. The experimental results so obtained are a significant corroboration to the correctness of the Pavlov hypothesis.     

Reflection of the process of conditioned reflex formation in shifts of the steady potential level]

In chronic experiments on rabbits with non-polarizable electrodes shifts of steady potential level (SPL) are recorded from the brain surface during extinction of the orienting reaction and formation of a conditioned defensive reflex. During each of these processes they have their typical parameters and are respectively denoted by the author as: orienting (appearing in response to a new stimulus), conditioned (to a signal atimulus), unconditioned (to an electro-cutaneous stimulus) and trace SPL shifts (developing after stimuli pairing). Trace shifts are the earliest SPL shifts originating as a result of pairing. They are manifested more regularly, than conditioned ones, considerably exceed them in amplitude, may differ from them in their sign and reach maximum values in a few seconds after the pairing. It has been assumed that formation of conditioned temporal connections depends above all on the appearance of a new kind of activity, resulting from pairings and reflected in the SPL trace shifts. This activity possibly constitutes the neurodynamic and metabolic processes underlying memory consolidation.     

The orienting response, and future directions of its development

The orienting response (OR) is a specific behavioral act directed towards extraction of information from the environment. Head and eye movements represent only the tip of the iceberg of internal responses, which includes vascular modifications, EEG changes, and event-related potentials. Two mechanisms of the OR have to be differentiated: voluntary and involuntary. In the event-related potential, such a differentiation is expressed in mismatch negativity (involuntary effect) and processing negativity (voluntary effect). Single unit studies have shown that hippocampal neurones are simulating specific features of the OR as a response to novelty. Repeated presentation of stimuli results in a selective habituation of novelty detectors in hippocampus and of the OR. The trace of a standard stimulus formed at the level of hippocampal neurones matches the features of the standard stimulus and can be called a "neuronal model of the stimulus." The OR is triggered by mismatch between the test stimulus and the elaborated neuronal model, and is activated by verbal instruction, by reinforcement during the initial stage of conditioned reflex elaboration, and by differentiation of signal and non-signal stimuli. A promising new area of practical application of the OR lies in the evaluation of a corridor of optimal functional state for efficient computer-based learning. Registration of the OR and defensive responses can be used for an objective evaluation of the functional state of the student, or, in a wider sense, of the industrial operator. New avenues of OR research are opened by recent techniques that isolate single-trial event related potentials, and their correlation with autonomic and behavioral manifestations of the OR.(ABSTRACT TRUNCATED AT 250 WORDS)     

Shifts in steady potential levels and changes in the cerebral bioelectrochemical potential during orientation and conditioned reflexes in rabbits]

The shifts of the steady potential level (SPL), recorded with non-polarized electrodes, and the changes in bioelectrochemical potential (BEChPs), recorded with platinum electrodes, were led from the rabbit brain surface in chronic experiments. The stimuli, that were new for the animal, caused only SPL shifts (0.1-0.3 mv), BEChPs showing no changes. BEChPs changed (by tenths to several millivolts) only in the process of the conditioned reflex formation, during the pairing of the conditioned and reinforcing stimuli, during which the shifts of SPL were also observed (up to 0.5-1 mv), different from the ones during the orienting reflex. Simultaneous recording of the SPL shifts and the changes in BEChPs showed that these phenomena are external manifestations of independent processes. It is suggested that the brain activity involved in the perception and the analysis of the informational value of a new stimulus, is connected with bioelectrical processes, rather than with the metabolic ones. During the formation of the defensive conditioned reflex, along with the enhancing of the activity connected with bioelectrical processes, other type of activity appears which is accompanied with considerable metabolic shifts.     

Nervous reactivity disturbances in patients with late post-traumatic encephalic syndromes.

A polygraphic study performed on 184 patients with late post-traumatic encephalic syndromes has shown marked nervous reactivity disturbances. The disturbances, estimated by testing for the electrographic components of the orienting reflex elicited by a repetitive auditory stimulus and for their habituation, were expressed by alterations in the intensity, resistance to habituation and sequence of habituation of the somatic, autonomic and EEG components. The character and severity of these disturbances depended on the mechanism behind the syndrome-inducing cranio-cerebral trauma, site of the impact and clinical picture of the syndrome.     

Reinstatement of short-latency responses after asymptotic Pavlovian conditioning training by the presentation of an extraneous stimulus

The purpose of this study was to examine whether the progressive disappearance of short-latency conditioned responses, or inhibition of delay, observed in Pavlovian conditioning with long inter-stimulus intervals, could be reverted by the presentation of a novel stimulus. In one experiment, two groups of rabbits received extensive training with a short (250 ms) or a long (1500 ms) tone that overlapped and terminated with a periorbital shock unconditioned stimulus. After training, the presentation of an extraneous stimulus prior to tone onset produced a reinstatement of short latency CRs in the group trained with the long CS, but did not affect CR latency in the group trained with the short CS. This finding is consistent with Pavlov's (1927) view that conditioning with long conditioned stimuli involves the acquisition of response tendencies in the early portion of the stimulus that are subsequently suppressed by the development of an inhibitory process.     

Functional differentiation of the theta-rhythm of the hippocampus in the cat

On the model of discriminating alimentary conditioned reflex with spatial separation of the sources of conditioned (CR, light flashes) and unconditioned (feeding trough) stimuli the theta-rhythm of the dorsal hippocampus was evaluated in cats. Two types of the theta-rhythm were observed in the spectrum of the hippocampal electrical activity: low-amplitude, consisting of a slow growing theta-waves (type I) and high-amplitude consisting of rapidly increasing theta-waves (type II). The type I theta-rhythm is sensitive to noradrenaline and correlates with behavioural forms directed immediately to the realization of alimentary motivation, while the type II is sensitive to serotonin and correlates with behavioural forms directed to the source of the conditioned stimulus. Enhancement of the type II theta-rhythm takes place during a delay of the expected conditioned stimulus. It is suggested that type I theta-rhythm reflects a level of activity of the brain structures connected with unconditioned mechanisms, with realization of biological motivations, while type II theta-rhythm is connected with conditioned reinforcing stimuli; it correlates with various forms of conditioned orienting reflexes and reflects the work of the "nervous model of reinforcing stimulus".     

Neuronal activity of the cerebral cortex in cats with conditioned inhibition

Unit activity of the somatosensory cortex was studied in chronic experiments on cats during alimentary instrumental conditioned reflex performance and elaboration of conditioned inhibition (CI). First presentations of the CI signal at the beginning of CI formation caused, due to orienting reaction to a new stimulus, a levelling of the response of the neurones to the positive conditioned signal included into the CI complex. At the stage of consolidated CI, this depression proceeded gradually during the development of conditioned inhibition caused by consecutive presentations of the nonreinforced CI combination. Two groups of neurones were involved in the process of the CI performance: one of them being the same which was activated also in response to positive stimulation during performance of the conditioned response, and the second one being areactive to the positive conditioned stimulus but reducing the frequency of the background activity.     

An attempt to confirm magnetic sensitivity in the pigeon,Columba livia

Summary An attempt was made to test the sensitivity of homing pigeons to weak magnetic variations of the order of the ones naturally occuring on earth. Pigeons were first subjected to a cardiac orienting reflex test to 50 magnetic stimuli and to 50 control stimuli presented alone and randomly interdigitated. They were then subjected to a differential nociceptive conditioning procedure using the same magnetic and control stimuli for 100 trials under each stimulus condition. Cardiac activity was used as an index of reactivity throughout the study. The tests were performed in uniform magnetic fields using 1 m diameter Helmholtz coils. Results indicate that the magnetic stimuli presentations did not evoke a cardiac orienting reflex when compared to the cardiac orienting response of control pigeons to a neutral luminous stimulus. Moreover, results from the conditioning tests indicate that the magnetic stimuli were not used by the pigeons as a cue presaging the forthcoming shock. It is concluded that, in the present experimental situation, homing pigeons did not respond to small changes in the ambiant magnetic field with changes in autonomic functioning. Results are discussed in the context of the inappropriateness of the stimuli and tests used to show magnetic sensitivity in birds.This research was carried out as part of a doctoral dissertation in the Département de Psychologie at the Université de Louvain (Belgique). The author is indebted to Professor G. Thinès, Director of the Centre de Psychologie Expérimentale et Comparée of the Université de Louvain for his guidance and encouragement as dissertation adviser. We would also like to express our appreciation to Dr. A. Vandenplass, director of the Institut Royal Metéorologique de Belgique and the Fédération Royale Colombophile de Belgique and to Professor J.L. Koenigsfeld from the University of Liège for their interest and cooperation in this research. Dr. Marco Citta and Louis Laurencelle gave computer assistance and Francois Labelle made the technical drawings. This research was supported by the Centre de Psychologie Expérimentale et Comparée and the Fédération Royale Colombophile de Belgique and made possible by a special leave of absence granted to the author by the Université du Québec à Montréal.     

Dynamics of heart rate response in sleeping infants exposed to tone stimuli

Heart rate, EEG, and motor responses were recorded following presentation of a series of 6–10 sound stimuli (2.5-s tones of 1000, 4000, and 250 Hz, 70 dB, interstimulus intervals 18–25 s) in neonates aged 9 to 22 weeks during stage 2–3 sleep. The infants (17 of 19) revealed heart rate (HR) changes in response to tone stimuli that consisted in an expanded form of three phases: (1) short-latency (at 1 s after tone presentation) HR deceleration, (2) HR acceleration with a maximum at 3–5 s, and (3) late HR deceleration at 6–9 s of the poststimulus interval. The occurrence rate of the first two phases of cardiac response is relatively constant during a series of stimuli, whereas the likelihood of late HR deceleration is the highest following the first tone presentation and decreases significantly when the stimulus is repeated. Differences in the dynamics and statistical analysis allow a relative independence of all the three response phases to be suggested. The HR acceleration phase is dramatically enhanced in association with the motor response elicited by the sound stimulus. The late HR deceleration phase occurs not only after the first presentation of stimuli, but also when they are repeated if they evoke EEG reaction (vertex potentials) in response to both the beginning and end of the tone sound. Possible mechanisms of the three phases of poststimulus HR changes are: the vagal cardiac reflex associated with the acoustic (adaptive) reflex, activation of sympathetic efferents in combination with the startle reflex, and secondary vagal deceleration of sinus rhythm likely to be associated with the processes of perception (detection) of a “novel” stimulus and to serve as an indirect sign of an orienting reaction.     

I. P. Pavlov on animal experiments]

The paper is dedicated to the 150th anniversary of academician I.P. Pavlov's birthday. Pavlov's points of view on vivisection are analyzed and are compared with the modern conception of ethics of carrying out experiments on animals. It is discovered that Pavlov's points of view are in accordance with the key positions of modern requirements to ethics of experimenting on animals which are adopted in the world practice.     

Varying temporal placement during CS of an added stimulus correlated with non-delivery of UCS.

This experiment extends Pavlov's method of contrasts for training a stimulus discrimination to the case of the cardiac conditional response in the rhesus monkey. It explores the parameter of temporal placement of an additional stimulus ("CS2") within a 10-sec CS (or "CS1"), with the appearance of the former stimulus on any trial signalling the absence of UCS (electric shock) on that trial. This experimental paradigm is a parallel to that of the "intruded stimulus" studies in operant conditioning. In both cases, several ways of describing the function of the added stimulus are possible, but all seem reducible to the same operational terms. Data were taken in the present study with respect to the form and latency of the cardiac rate changes produced by intrusion of CS2 (light), across a range of placements varying from simultaneity with CS1 (a different light) onset to two sec before UCS would have been delivered. The control of CS2 over the cardiac rate CR was occasionally exhibited with a latency as short as three beats after stimulus onset. The order of CS2 temporal placements to which a subject was exposed was a factor in determining the form of the conditioned cardiac rate response to CS1.