Psychological Adaptation Potential of the Personality: Peculiarities of Event-Related EEG Potentials

In a group of 68 adults of both sexes, we examined correlations between the level of psychological adaptability of the personality (diagnosed using the Maklakov questionnaire) and parameters of event-related potentials (ERPs) recorded in the course of performance of two behavioral test acts including a motor component. In task A, it was necessary to maximally rapidly press the button after an imperative signal preceded by a warning signal, while a definite time interval (limited by two pressings of the button) should be measured in task B. Parameters of the contingent negative variation, CNV, potential P300 and, in task B, readiness potential, RP, were measured in C3 and C4 leads. High amplitudes of ERPs (RP, P300, and CNV in task A) and smaller variability of the indices of working efficiency corresponded, in the whole, to higher estimates of psychological adaptability in general and of separate aspects of the latter estimated according to the scales of the used questionnaire. Probable mechanisms of the peculiarities of neurodynamic constitution determining the level of the psychological adaptability of the individual, on the one hand, and of the ERP parameters, on the other hand, are discussed.     

Correlations between the level of aggressiveness of personality and characteristics of event-related EEG potentials

In a group of 76 adults of both sexes, we examined interrelations between the level of aggressiveness of the individual (diagnosed using the Buss-Durkee Hostility Inventory) and parameters of event-related EEG potentials (ERPs) recorded under conditions of two behavioral test acts including a motor component. Within the framework of task A, the subject must push a button with the shortest delay after an executory signal preceded by a warning signal; the time of sensorimotor reaction was measured. Under these conditions, we recorded the contingent negative variayion (CNV) and the P300 potential. In the case of task B, it was necessary to measure a definite time interval limited by two pushings of the button. Under these conditions, the readiness potential (RP) was recorded in addition to the CNV and P300. The C3 and C4 leads were used (according to the 10–20 system); the time constant of an amplification tract was 10 sec. Despite natural broad interindividual variability, high amplitudes of the recorded ERPs (RP, CNV, and P300) in general corresponded to lower indices by scales of the Buss-Durkee inventory and smaller values of the indices of aggressiveness and hostility. These interrelations are, probably, based on the fact that both characteristics of aggressiveness of the personality and EEG amplitude parameters are to a considerable extent determined by hereditary factors. It is believed that the respective peculiarities of the neurodynamic constitution of the individual are to a great extent dependent on the specificities of organization and functioning of a few neurotransmitter (in particular, aminergic) and neurohumoral systems. Neirofiziologiya/Neurophysiology, Vol. 39, No. 2, pp. 154–164, March–April, 2007.     

Somatosensory cortical unit responses during avoidance conditioning to sound

Unit responses of the primary somatosensory cortical-projection area were recorded in cats with established conditioned avoidance to sound during the conditioned response. Five types of changes in unit activity were distinguished during the conditioned reflex. The responses were 400–1000 msec in duration; their time of onset coincided with that of the expected reinforcing stimulus. As a rule the change in unit activity was preceded by changes in the electromyogram of the corresponding limb muscles. Among neurons responding to the conditioning stimulus, the proportion with a short latent period of response to electrical stimulation of the skin was less than during investigation of ordinary unit responses to the same stimulus.     

Correlations of the Peculiarities of the Motivational Sphere and Characteristics of Event-Related EEG Potentials in Humans

We studied the relations between generalized characteristics of the state of the motivational sphere, the levels of need for achievements (N-Ach) and achievement motivation (AchM) typical of an individual, and the parameters of cerebral event-related potentials (ERPs). The examined group included 70 adults of both sexes. The ERPs were recorded in the course of realization of two behavioral test acts with motor components. In task А, the subject should press a button with the minimum delay with respect to an imperative signal preceded by a warning signal (with the measurement of the time of sensorimotor reaction); in this case, the contingent negative variation (CNV) and Р300 potential were recorded. Under conditions of task B, the subject should measure a definite time interval limiting the latter by two pushings of the button; in this case, the readiness potential (RP) was recorded in addition to CNV and Р300. The ERPs were recorded in the С3 and С4 leads (according to the 10-20 system). The peculiarities of the motivational sphere were diagnosed using Orlov’s and Mechrabian’s questionnaires. We found that a relatively high amplitude of the early CNV component (СNV-O) and low amplitudes of the integral CNV and Р300 in task A and a low amplitude of the RP can serve as task B-related EEG markers of a high NA level. In task A, high levels of the AchM correlated with higher amplitudes of the CNV and Р300, and amplitudes of these potentials were higher in the left hemisphere. The observed interrelations were probably determined by a considerable dependence of the N-Ach and AchM characteristics, on the one hand, and CNV amplitude parameters, on the other hand, on the hereditary factors, in particular neurochemical ones. It is obvious that such peculiarities of the neurodynamic constitution of an individual are, to a considerable extent, determined by the specificity of organization and functioning of a few neurotransmitter (in particular aminergic) and neurohumoral systems.     

Responses of motor cortex neurons of the cat to auditory stimulation and their role in the instrumental food reflex

The responses of motor cortex neurons in the cat to the presentation of a single auditory click and a series of 10 clicks presented with 1,000/sec frequency were studied under conditions of chronic experiments before and after the development of an instrumental food reflex. After reflex development a single presentation of a positive conditioned stimulus (single click) markedly influenced for 7 sec the appearance of instrumental movements. At the same time, the immediate responses of motor cortex neurons to presentation of the conditioned auditory stimulus had no impact on the appearance in the motor cortex of discharges leading to the realization of instrumental movements. Consequently, motor cortex neurons do not require activation from afferent sensory inputs for the generation of such discharges. The immediate neuronal responses to conditioned stimulation did not inhibit the realization of the instrumental reflex. It is proposed that they are associated with the realization of motor function in the unconditioned defensive response evoked by the presentation of an auditory stimulus. The presence or absence of responses to auditory conditioned stimulation was dependent upon the signal meaning of the stimulus, its physical parameters, and the degree of excitability of the animal.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 17, No. 4, pp. 539–550, July–August, 1985.     

Analysis of changes in the electrical activity of the neocortex in dogs during the formation of the stereotype of food-procuring conditioned reflexes in them

A system of food-procuring conditioned reflexes (dynamic stereotype after I.P. Pavlov) was elaborated in dogs. In the interstimuli periods, 0.6 to 0.8 sec. prior the action of the conditioned stimulus, they exhibited a "state of expectancy" characterized by an increase of frequency (up to 80 per sec.) of potential oscillations of a small amplitude (20 to 30 mcv) and their pronounced sychroneity, predominantly in the anterior parts of the neocortex. The conditioned signal acting against such background produced specific reactions in the form of a limited number of bursts (3 to 4 in 0.5 sec.) of highfrequency (up to 100 per sec.) synchronized activity (HSA) of considerable amplitude (50 to 60 mcv) which always preceded conditioned reactions, being in certain temporal relations with them. A correlation-spectral analysis has shown that in the HSA period, electrical activity became considerably more regular; in the intensity spectra the extreme frequencies of the analyzed band (5 to 7 c/s and 90 to 100 c/s) became prominent, and in most cases high values of the coherence function were due to them. HSA reactions are regarded as a major link in the trigger mechanism of conditioned food-procuring reactions.     

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.     

Relation between warning stimuli and contingent negative variation in man

Seven right handed male students were submitted to standard and target paired auditory stimuli to determine the relationship between contingent negative variation (CNV) and the slow negative waves following non paired stimuli. The warning stimuli informed subjects whether or not the impending unconditional stimulus implied a motor response. Subjects were instructed to execute the motor task at less than one second after unconditional stimulus. They were informed that the standard warning stimulus would be followed by an additional stimulus which confirmed its detection. Recordings of standard warning stimulus condition showed a subsequent increase in CNV amplitude. This significant increase appeared to be related to an enhancement in the subject's expectation towards the additional stimulus. The lowered CNV voltage in target condition seemed to be linked to the instructions, which involved a motor preparation after the imperative stimuli occurrence. It is suggested that the CNV may represent not only a general anticipatory but also an orienting process related to the signal value of the warning stimulus.     

Individual personality-related characteristics of event-related EEG potentials recorded in an experimental situation requiring production of time intervals

Event-related EEG potentials (ERP) were recorded from 75 tested adult men and women; recording was performed from C3 and C4 points. The experimental situation required internal counting of time intervals limited by two pushes of a button. The experimental paradigm provided a substantial level of uncertainty, and a high level of attention needed to be maintained. The tested subjects were not informed by the experimenter about the precise value of the preset time interval; they knew only its limits, 17–23 sec. The subject obtained information about the agreement or disagreement between the produced interval and its value preset by the experimenter by visual feedback signals obtained 2 sec after termination of counting; in the case of agreement the subject had to perform a confirming (third) push of the button. Pushes were preceded by readiness potentials (RP); contingent negative variation (CNV) developed before the feedback signals, and the latter were accompanied by P300 potentials. Significant positive correlations were found between the parameters of RP and P300 in both hemispheres. In general, ERP were characterized by very high interindividual variability, which in a few respects correlated with the personality-related characteristics of tested subjects evaluated by psychological testing with the use of corresponding questionnaires. In particular, under the experimental conditions used, negative correlations were observed between the RP amplitude and psychotism indices, CNV amplitude and emotional stability; CNV amplitude and extroversive features, and P300 amplitude and domination properties of a person. Positive correlations were observed between the CNV amplitude and autia factor (according to Eysenck’s PEN and Cattell’s 16 PF questionnaires). We suppose that correlations between the personal psychical features and ERP parameters are grounded in both inherited constitutional specificities of the nervous system and neurochemical/structural modifications in the brain determined by the acquired vital experience.     

A Coronary-Prone Type of Personality: Peculiarities of Event-Related EEG Potentials

In a group of 70 adults of both sexes, we examined interrelations between the estimates of expression of a coronary-prone type (type A) of the personality (measured using the Jenkins questionnaire) and the parameters of event-related EEG potentials (ERPs). The latter potentials were recorded in the course of performance of two behavioral test tasks including motor components. Within the framework of the “A” task, the subject is had to maximally rapidly push the button after a signal with warning (with measurement of the latency of the sensorimotor reaction); under these conditions, we recorded the contingent negative variation (CNV) and P300 potential. In the case of the “B” task, a definite time interval was to be measured and limited by two pressings of the button. In this task, the readiness potential (RP) was recorded in addition to the CNV and P300. The C3 and C4 EEG leads (according to the 10–20 system) were used. Within the framework of the “A” task, subjects belonging to the coronary-prone type were characterized by the lowest amplitudes of the CNV and its separate components and also by greater amplitudes and relatively long latencies of the P300 wave. Persons of type B were distinguished by the highest CNV amplitudes in both hemispheres, while values of the P300 amplitude in this group were usually medium. In the “B” task, representatives of type A demonstrated the lowest RP and P300 amplitudes, especially clearly pronounced negative CNVs in the left hemisphere, and relatively long P300 latencies; individuals belonging to type B showed the highest RP and CNV amplitudes in the right hemisphere and medium values of the P300 amplitude. The correlations found are probably due, to a considerable extent, to the fact that both characteristics of the behavioral types A and B and amplitude parameters of ERPs depend significantly on genetically determined neurochemical factors, namely specificities of organization and functioning of a few neurotransmitter (in particular, aminergic) and neurohumoral systems.     

Neuromagnetic responses elicited by auditory stimuli in dichotic listening

We measured N1m and P2m components of the magnetic field responses that were elicited by random series of a tone burst given to the left ear and a monosyllabic speech sound given to the right ear. The magnetic responses had smaller amplitudes and/or longer peak latencies of the N1m and the P2m when the stimulus was preceded by a stimulus at the same ear than when preceded by a stimulus at the different ear. This reduction of the response by preceding stimulation of the same ear was significant over the hemisphere contralateral, but not ipsilateral, to the ear stimulated. The peak latencies of N1m and P2m were significantly longer in the response over the hemisphere contralateral than ipsilateral to the stimulated ear.     

A simple, single, trial-learning paradigm for conditioned increase in natural killer cell activity.

A change in natural killer (NK) cell activity can be conditioned with one trial learning when conditioned stimulus (CS) precedes the unconditioned stimulus (US). To avoid the problems associated with two reexposures in our earlier studies, we have developed a reliable and simple conditioning protocol utilizing the one trial learning and one reexposure to the odor CS. The conditioned change in NK cell activity was significantly different (P less than 0.05) from the control groups of mice. The paradigm is short and simple in that the conditioned change could be demonstrated within 3 days. We have also compared the effects of temporal association of CS and US on conditioned increase in NK cell activity. Forward conditioning (CS preceded the US) demonstrated a conditioned change, but the backward conditioning protocol did not. The paradigm provides a reliable approach to the study of mechanisms of the phenomenon of odor-NK conditioning.     

Responses of somatic cortical neurons during the conditioned placing reflex in cats

Unit activity was studied in areas 3 and 4 during the conditioned placing reflex in cats. Responses of somatic cortical neurons in this case were shown to develop comparatively late — 80–100 or, more often, 200–450 msec after the conditioned stimulus. In the motor cortex responses preceded movement by 50–550 msec, whereas in the somatosensory cortex they usually began simultaneously with or after the beginning of the movement. Judging from responses of somatic cortical neurons, the placing reflex is realized by the same neuronal mechanism as the corresponding voluntary movement. The differential stimulus and positive conditioned stimulus, after extinction of the conditioned placing reflex, evoked short-latency spike responses lasting 250–350 msec in the same neurons as took part in the reflex itself. In these types of internal inhibition, responses of the neurons were thus initially excitatory in character. Participation of the neurons in the conditioned placing reflex and its extinction, disinhibition, and differentiation, is the result of a change in the time course of excitatory processes and is evidently connected with differential changes in the efficiency of the various synaptic inputs of the neuron.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 14, No. 4, pp. 392–401, July–August, 1982.     

Change in the signal properties of a conditioned stimulus during two-way avoidance conditioning in rats

Acquisition of two components of conditioned active avoidance behavior by rats was studied. First presentations of electroshock evoked a number of different behavioral reactions. However, after five trials many rats learned to escape punishment running away to another part of a shuttle-box. The efficiency of the avoidance reaction conditioning significantly depended on the ability of an animal to learn the correct escape reaction to the unconditioned stimulus. However, some animals were incapable for acquisition of the conditioned reaction despite their high level of successful escapes. Increase in the number of negative reactions to the conditioned stimulus (light) at the next stage of learning suggests that the conditioned stimulus becomes the signal of forthcoming punishment. The ability of an animal to identify the conditioned stimulus as a signal significantly affected the efficiency of conditioned avoidance acquisition.     

Neuronal responses in area 7 of the cat cortex during defensive conditioning

Responses of neurons in area 7 of the parietal association cortex during and after formation of a defensive conditioned reflex to sound were recorded in waking cats. Changes in spike responses of the neurons as a result of the onset of conditioned reflex limb movements were observed in 68% of neurons. Spike responses of neurons formed as a result of learning appeared only if conditioned-reflex limb movements appeared, and they were not observed if, for some reason or other, movements were absent after presentation of the positive conditioned stimulus or on extinction of the reflex. Responses of 46% neurons to conditioned stimulation preceded the conditioned-reflex motor responses by 50–450 msec. The remaining responding neurons were recruited into the response after the beginning of movement. Characteristic spike responses of neurons to the conditioned stimulus appeared 500–900 msec before the beginning of movement and, in the case of appearance of special, "prolonged" motor responses of limb withdrawal, evoked by subsequent reinforcing stimulation.     

Effect of diazepam on the formation and reproduction of conditioned cortical reactions in man

Intramuscular injections of seduxen (10 mg), a benzodiasepin drug, with expressed tranquilizing and alarm suppressing effects, were used with the aim of experimental testing of a hypothesis on the neural mechanism of conditioned changes of the P300 wave. Under the action of seduxen no temporary connections could be formed between a perceived nonverbal visual stimulus and a unrecognized emotional word. The seduxen did not suppress the conditioned cortical reaction acquired due to combination of nonverbal stimulus with unrecognized emotional word. The suggestion is made that the necessary condition of temporary connection elaboration by means of a unrecognized verbal stimulus is the implication of the limbic structures where negative emotional reactions are integrated.     

Component-Specific Self-Regulation of Slow Cortical Potentials and its Effect on Behavior: An Exploratory Study

In the present study, the possibility of component-specific self-regulation of the contingent negative variation (CNV) and the functional significance of the iCNV (initial or early CNV component) and tCNV (terminal or late CNV component) were investigated in twenty-four healthy volunteers. The subjects were able to achieve control over a particular CNV component within four sessions. Regulation of the tCNV was more successful than for the iCNV. Specific control over iCNV was associated with strategies mainly related to the pre-stimulus interval or the warning stimulus (S1), while regulation of the tCNV was assigned to activities during the whole interstimulus interval or around the imperative stimulus (S2). It can be concluded that component-specific regulation of the CNV can be used in studies of the psychophysiological meaning of this potential, representing different stages of information processing. The role of cortical pre-activation in the generation of the iCNV and the phasic performance-directed activation of the tCNV can be hypothesized.     

Locus of Psychological Control and Peculiarities of Event-Related EEG Potentials

In a group including 74 adults of both sexes, we examined interrelations between the locus of psychological control (diagnosed using the Rotter questionnaire) and parameters of event-related EEG potentials, ERPs, recorded in the course of performance of two behavioral test acts with a motor component. Task A corresponded to maximally fast pushing on the button after a signal with warning; the time of the sensorimotor reaction was measured. Task B included internal counting of a definite time interval limited by two pushings on the button. Under these conditions, we recorded the contingent negative variation (CNV), the P300 potential, and, in task B, the readiness potential (RP). EEG leads C3 and C4, according to the 10-20 system, were used. Internals (estimates by the questionnaire, 6 stens or higher) were characterized by higher amplitudes of the terminal CNV (CNV-T), integral CNV, and P300 in task A, by greater RP and CNV amplitudes in task B, and also by shorter reaction times and their smaller dispersion. It should be supposed that the corresponding peculiarities of the neurodynamic constitution of an individual are determined, to a considerable extent, by the specificity of organization and functioning of a few neurotransmitter (aminergic in particular) and neurohumoral systems.     

Extension of the CS past the US can facilitate conditioning of the rabbit's nictitating membrane response

Five experiments were conducted in which the onset of a tone conditioned stimulus (CS) preceded the unconditioned stimulus (US) by 500 ms. Across experiments, the offset of the CS was extended past the offset of the US by values ranging from 0 ms to 40000 ms. Extensions of the CS of 2000 ms or greater produced acquisition of a conditioned response (CR) that was as fast or faster than in the no-extension condition (0 ms). While extension of a forward tone CS after the US enhanced excitatory conditioning, insertion of another CS (light) in a purely backward relationship with the US passed only a retardation test, indicative of latent inhibition, and not a summation test needed for conditioned inhibition. The results add to the evidence that excitatory and inhibitory processes are both engaged following US offset. Alternative theories of CS processing are discussed.     

Probability analysis of elements of rat behavior after sudden and signalled interruption of food reinforcement

Probability analysis was carried out of the appearance of single elements of rats behaviour in the process of extinction of a conditioned alimentary motor reflex. The dynamics of effector behavioural components at a sudden cessation of reinforcement (usual schedule of extinction) was compared with cessation of reinforcement signalled by a previously differentiated signal and with reinforcement cessation preceded by a stimulus initially unknown to the animal. If the reinforcement cessation is signalled by a previously differentiated (negative) stimulus, in response to its action the animals "loose the aim", what is revealed in a rapid complete reduction of all elements of the goal-directed alimentary behaviour. Obviously differentiation signal actualises the memory trace of "nonreinforcement" which was formed in the previous negative experience of the animal; this is revealed in accelerated inhibition of the alimentary motor reflex under extinction.