Biomedical subjects

N Birbaumer

Publications and source records attributed to N Birbaumer.

At least 163 records · Page 9Linked to original sources

PubMed1993

Cortical self-regulation in patients with epilepsies.

The present study aimed at investigating to what extent the regulation of excitability in cortical networks, as indicated by surface-negative slow cortical potentials (SCPs), is impaired in epileptic patients and to what extent training of SCP self-regulation by means of biofeedback and instrumental learning procedures might affect seizure frequency. Twenty-five patients suffering from drug-refractory epilepsies (complex focal, grand mal, and absence type of seizures) participated in 28 1-h sessions of feedback and instrumental conditioning of their SCPs. Subjects' EEGs were obtained from the vertex. Depending on discriminative stimuli DC shifts towards increased or suppressed negativity relative to the pre-trial baseline were demonstrated by on-line visual feedback during intervals of 8 s each; each session comprised 110 trials. While performance on the SCP self-regulation task was initially below normal (as compared to healthy subjects), significant increases in SCP control were achieved by the patients across the 28 training sessions. In 18 patients at least 1-year follow-up data are available. Changes in seizure frequency were related to transfer of SCP control with six of the patients becoming seizure-free. Age affected the ability to acquire SCP control and its impact on seizure frequency.

Adolescent↗

PubMed1993

Comparison of the efficacy of electromyographic biofeedback, cognitive-behavioral therapy, and conservative medical interventions in the treatment of chronic musculoskeletal pain.

In this study, three types of treatments for chronic musculoskeletal pain were compared. Fifty-seven patients who suffered from chronic back pain and 21 patients who suffered from temporomandibular pain and dysfunction were randomly assigned to either electromyographic (EMG) biofeedback, cognitive-behavioral therapy, or conservative medical treatment. At posttreatment, improvements were noted in all three treatment groups, with the biofeedback group displaying the most substantial change. At the 6- and 24-month follow-up, only the biofeedback group maintained significant reductions in pain severity, interference, affective distress, pain-related use of the health care system, stress-related reactivity of the affected muscles, and an increase in active coping self-statements. Treatment outcome was predicted by chronicity and treatment-specific variables. Analysis of attrition showed a significant effect for therapist and extent of somatic pathology. Results suggest that pain patients who suffer from musculoskeletal pain problems and display few physical disabilities may profit the most from short-term EMG biofeedback treatment.

Adult↗

PubMed1993

The cerebellum and cognitive functions in humans.

Recent neuropsychological studies have given rise to the hypothesis that the cerebellum is involved in nonmotor cognitive functions. The interpretation of these findings is, however, restricted by methodological problems, such as heterogenous patient samples. The present study compared patients with pathology confined to the cerebellum and patients with combined cerebellar and brainstem lesions to matched normal controls on a range of memory and learning tasks. Two procedural learning tasks were also conducted, involving perceptual (mirror reading) and conceptual skill acquisition (the Tower of Hanoi task). Patients with damage to both cerebellum and brainstem, but not patients with cerebellar pathology alone, showed impairments on memory and visuoconstructive tasks and evidence of frontal lobe dysfunction. Cerebellar damage had no effect on skill acquisition. These results do not support the hypothesis of cerebellar involvement in procedural learning per se.

Adult↗

PubMed1993

Classical conditioning after cerebellar lesions in humans.

We explored classical conditioning in human subjects who had lesions in their cerebellar circuitry. Seven patients with damage to cerebellar structures and matched control subjects underwent simple delay tone-airpuff conditioning. Eyelid conditioned response (CR) acquisition was severely disrupted in the patient group, whereas autonomic CRs and slow cortical potentials developing between conditioned stimulus (CS) and the unconditioned stimulus (UCS) were unaffected. Results are consistent with animal studies and earlier case reports indicating that intact cerebellar structures are necessary for the acquisition of classically conditioned motor responses.

Adult↗

PubMed1993

Does activation of the baroreceptors reinforce differential Pavlovian conditioning of heart rate responses?

High- and low-pitched tones (CS+ and CS-) signalled baroreceptor stimulation or inhibition (US+ and US-) on 6-s conditioning trials (n = 128). Baroreceptor stimulation was induced by the phase-related external suction (PRES) method of Rau et al. (1992) in which a brief pulse of negative external pressure is applied to the neck at systole and one of positive pressure at diastole within each cardiac cycle (the reverse sequence is used for baroreceptor inhibition). Changes in heart period (R-R intervals) confirmed that PRES manipulated the baroreceptors in the presence of CS+ and CS- without habituation over conditioning trials. However, conditioned heart period responses were not observed on test trials (n = 32) in which CS+ and CS- were presented with the baroreceptor manipulation removed. Subjects were unable to state which CS had signalled baroreceptor stimulation and inhibition when given PRES-alone trials after the conditioning phase (differential attention thus controlled). These results (a) confirm that the differential effect of the two PRES stimuli was specific to the baroreceptors and (b) support earlier studies that have found that differential conditioning is impaired when CS-US relations are not processed in attention. We discuss implications regarding when baroreceptor firing might be discriminable and reinforcing.

Adult↗

PubMed1993

Baroreceptor stimulation alters cortical activity.

The arterial baroreceptors constitute an essential sensory link for the short-term regulation of blood pressure and may also influence higher cortical function. The present study was undertaken to evaluate previous reports of such a cortical influence under conditions of psychologically controlled, mechanical baroreceptor stimulation. This control was achieved by use of PRES (phase-related external suction), a modified neck suction technique. PRES applies short suction bursts that have a different impact on baroreceptors depending on their timing within the cardiac cycle and has the advantage that subjects cannot easily discriminate between conditions of stimulation and inhibition. Electroencephalograms were recorded from 22 subjects during PRES manipulations. A surface-negative shift of about 10 microV developed during the cuff manipulations. Over frontal-central regions, this shift was smaller during baroreceptor stimulation than during inhibition. These data provide support for the proposal that baroreceptor activation influences cortical activity.

Adult↗

PubMed1993

Behavioural treatment of slow cortical potentials in intractable epilepsy: neuropsychological predictors of outcome.

The study aimed to explore the predictive value of neuropsychological tests within the context of acquisition of slow cortical potential (SCP) self-control, a technique which has beneficial effects on seizure frequency in epilepsy. Patients with epilepsy who successfully achieved SCP control had longer digit or block-tapping spans than less successful patients. Patients who showed a better learning rate across training also displayed better verbal memory and learning abilities. Seizure reduction was related to block-tapping spans only. The results indicate that measures of attention, as indicated by digit spans or block-tapping spans, offer some predictive value for acquisition of SCP control and treatment outcome, whilst measures of visuospatial or frontal lobe function are unrelated to SCP acquisition and seizure reduction.

Adolescent↗

PubMed1993

Effects of baroreceptor stimulation on sensorimotor control of the hand.

Finger movements are presumed to be controlled by somatosensory and motor areas of neocortex via the corticospinal tract. Since baroreceptor activation appears to reduce central nervous system activity, an effect on sensorimotor control during precise manual manipulations is expected. To test this hypothesis, motor responses to slow and fast perturbations during grasping of a small object (precision grip) were examined. Baroreceptor activation was manipulated with the phase-related external suction (PRES) technique, which allows the application of baroreceptor stimulation and control conditions in a well-controlled and indiscernible way. Motor reactions following slow perturbations were influenced in the expected way in good-performance subjects. The time to stop slow perturbations was longer and the electromyographic (EMG) activity of the small thumb muscles was lower during baroreceptor stimulation than in the control condition. These effects did not appear in the fast-perturbation task. Fast perturbations were followed by EMG activity onset after about 50 msec, which indicates that a prominent part of the EMG activity must be attributed to a more automatic motor response. EMG activity following slow perturbations began after about 90 msec, and it may be assumed that these motor reactions are primarily under voluntary control. The fact that we found effects of baroreceptor stimulation in slow but not in fast perturbations could have been caused by at least partially different pathways utilized for automatic versus voluntary motor responses, which seem to be differentially vulnerable to baroreceptor activation. An electrocortical sign that precedes voluntary movements is the Bereitschaftspotential, or readiness potential. Since this potential is a slow brain potential, and baroreceptor activation is known to reduce slow brain potentials, it is plausible that baroreceptor activation primarily affects motor responses following slow but not fast perturbations.

Adult↗

PubMed1992

Dimensional analysis of the human EEG and intelligence.

The purpose of this study was the determination of the relationship between the dimensional complexity of the electroencephalogam (EEG) and the level of intelligence in humans. In two experiments 34 male subjects were divided into two groups, with high and low levels of intelligence (as measured by the intelligence quotient (IQ)). During a resting phase and various mental imagery conditions the EEG was recorded from several scalp sites. Nonlinear analysis, based on the theory of deterministic chaos, revealed that subjects with high IQs demonstrate higher dimensional complexity of the EEG attractors than subjects with low IQs only during resting conditions. During performance of the imagery tasks the less intelligent subjects increase the complexity of electrical brain dynamics such that IQ-dependency vanishes. The gross (mass) neuronal manifestation of general intelligence seems to depend on task conditions and may be related to the individual brain dynamics only when no specific task is present.

Adult↗

PubMed1992

Self-regulation of slow cortical potentials in psychiatric patients: schizophrenia.

Slow cortical potentials (SCPs) are considered to reflect the regulation of attention resources and cortical excitability in cortical neuronal networks. Impaired attentional functioning, as found in patients with schizophrenic disorders, may covary with impaired SCP regulation. This hypothesis was tested using a self-regulation paradigm. Twelve medicated male schizophrenic inpatients and 12 healthy male controls received continuous feedback of their SCPs, during intervals of 8 s each, by means of a visual stimulus (a stylized rocket) moving horizontally across a TV screen. The position of the feedback stimulus was a linear function of the integrated SCP at each point in time during the feedback interval. Subjects were required to increase or reduce negative SCPs (referred to pretrial baseline) depending on the presentation of a discriminative stimulus. The correct response was indicated by the amount of forward movement of the feedback stimulus and by monetary rewards. Schizophrenics participated in 20 sessions (each comprising 110 trials), while controls participated in 5 sessions. Compared with the healthy controls, schizophrenics showed no significant differentiation between negativity increase and negativity suppression during the first sessions. However, in the last 3 sessions, patients achieved differentiation similar to controls, demonstrating the acquisition of SCP control after extensive training.

Adult↗

PubMed1992

Effects of inhaled nicotine on instrumental learning of blood pressure responses.

The present study investigated the effects of biofeedback of arterial blood pressure on cortical, peripheral, and psychological measures and the dependence of these effects on nicotine. Four groups of subjects, nonsmokers, and habitual smokers who smoked cigarettes during the experimental sessions containing 0.3, 0.8, or 1.5 mg nicotine, respectively, participated in a feedback paradigm in which continuous feedback of mean blood pressure was provided for intervals of 8 s each. While tonic blood pressure did not differ between the groups, the ability to modulate blood pressure (under feedback conditions) was restricted in smokers as compared to nonsmoking subjects; increasing nicotine dosage was accompanied by poorer performance. Independently of habitual smoking and nicotine doses, heart rate increased during feedback and under conditions of blood pressure increase. In smokers, activity in the alpha band was reduced in a dose-dependent manner. Slow cortical potentials (SCPs) during the feedback interval varied with self-induced blood pressure changes in nonsmokers (blood pressure increase was accompanied by reduced surface-negative potential shifts and vice versa), while SCP variations during feedback conditions were small in smokers, more so under the influence of 0.3 and 0.8-mg nicotine, less so under 1.5 mg. Verbal reports suggest that awareness of performance strategies may not be a necessary variable for performance on the blood pressure regulation task.

Adult↗

PubMed1992

Discrimination of muscle tension in chronic pain patients and healthy controls.

The purpose of this study was to assess the perception of muscle tension in chronic pain patients and healthy controls. Twenty chronic back pain patients, 20 patients who suffered from temporomandibular pain and dysfunction, and 20 healthy controls were instructed to produce eight different levels of muscle contraction in either the m. masseter or the m. erector spinae. Each level was produced three times; trials were presented in random order. Analyses of the accuracy and the sensitivity of discrimination of muscle tension levels revealed that the patients were less able to perceive muscle contraction levels correctly and that they underestimated their actual levels of muscle tension. Patients and controls did not differ in the extent to which they contracted muscles not involved in the task. Patients suffering from musculoskeletal disorders seem to display a genuine deficit in discrimination of muscle tension that is related to neither local physiological changes at the site of pain, lack of motivation, in-attention, nor fatigue.

Adult↗

PubMed1992

Self-regulation of slow cortical potentials in psychiatric patients: depression.

Findings on depressive patients indicate that depressives have electrophysiological characteristics similar to those of schizophrenics, in that they exhibit reduced Contingent Negative Variation (CNV) amplitudes and more distinct Postimperative Negative Variations (PINVs) than normal controls. In a biofeedback experiment, 8 medicated male inpatients with the DSM III-R diagnosis of "Bipolar Disorder, Depressive," and "Major Depression" demonstrated no impairment in the self-regulation of Slow Cortical Potentials (SCP) in comparison to schizophrenics in terms of increasing and suppressing negativity. Continuous visual SCP feedback is presented to the patient as a horizontally moving rocket in a video game format. The direction changes of the rocket represented SCP changes at each point in time, recorded by the central EEG (based on the pretrial baseline). Depressives demonstrated SCP self-regulation across 20 sessions, although with many between-and-within variations. The 8 male controls were unable to regulate their SCPs across 5 sessions. This result contradicts other findings of our laboratory on normal controls. Motivational factors and insufficient operant reinforcement (financial reward) may have facilitated this effect.

Adult↗

PubMed1992

The scalp distribution of the fractal dimension of the EEG and its variation with mental tasks.

The insights gained by the concept of deterministic chaos for the EEG is that this seemingly disordered process may be governed by relatively few simple laws which could be determined. One of the quantitative measures of a complex dynamical system is that of its dimension. The term 'dimension' refers to the ability of a space to contain a set of points. We estimated the correlational dimension of the EEG and compared the outcome to traditional Fourier analyses. In addition, we tested the hypothesis that the EEG can be described as filtered noise. Data from 15 electrode sites and 31 subjects are reported in the present study. We have utilized a variety of tasks that cut across sensory modalities including touch, vision, and imagery which reflect neuropsychological processes that differentially engage areas of the cortex in the first part of the study. In the second part, the differences between the perception of an object and the imagination of the same object were evaluated. The outcome shows variations between scalp sites for all measures and also variations between tasks in terms of dimensionality of the EEG. The hypothesis of a higher dimensionality ("complexity") of imagery compared to actual perceptual processing was confirmed. A statistical comparison between the maps generated by means of the various measures shows that different informations are extracted when using the different measures. There is also statistical evidence that the EEG cannot completely be described by the model of filtered noise.

Adult↗

PubMed1992

Modulation of slow cortical potentials by instrumentally learned blood pressure responses.

We assessed whether instrumentally-learned pressor responses inhibit electrocortical activity, as predicted by learning theories of idiopathic hypertension. Subjects received beat-by-beat feedback for increases and decreases in mean arterial pressure measured from the finger (Peñáz method). Slow potentials were recorded from the midsagittal line during the final training session. Also recorded at this time were heart rate, eye movements, respiration, and post-session verbal reports of the subject's control strategies. Thirteen of 14 subjects differentiated blood pressure increases and decreases at p less than .05 or better during the final session (within-subject discriminative operant procedure). Slow potentials were less negative on blood pressure increase compared to decrease trials at all midsagittal sites (p less than .02), indicating relative cortical inhibition by pressor responses. This effect occurred even though subjects reported tensing of muscles on increase trials (p less than .01), a behavioral activity previously associated with augmented rather than diminished cortical negativity. On increase trials slow potentials shifted toward positivity just prior to heart rate deceleration (the latter effect confirming activation of the baroreceptors).

Adult↗

PubMed1992

Symptom-specific psychophysiological responses in chronic pain patients.

Symptom-specific psychophysiological responding was assessed in 20 chronic back pain patients, 20 patients suffering from temporomandibular pain and dysfunction, and 20 matched healthy controls. Surface EMG from the lower and upper back, the masseter, and the biceps muscles, and heart rate and skin conductance level were continuously recorded during adaptation, resting baseline, and stressful and neutral imagery phases. Univariate and multivariate analyses of variance were performed on raw data as well as data corrected for autocorrelation. The results showed significantly higher EMG reactivity which was lateralized to the left side at the patients' site of pain but not distal sites. This hyperreactivity was observed only during stressful imagery. The healthy controls displayed a significantly higher response in heart rate, but skin conductance level was not significantly different. The results are interpreted as indicative of idiosyncratic muscular response patterns to personally relevant situations at the site of pain in patients suffering from chronic muscular pain.

Adult↗

PubMed1992

[Biofeedback of slow brain potentials].

Slow cortical potentials constitute neurophysiological indicators of cortical excitability. Behaviorally they correlate with attention and motor preparation. A system for biofeedback and self-regulation of slow cortical potentials (SCP) has been developed. The portable system allows on-line visual feedback of filtered and corrected slow brain potentials in a predetermined sequence of trials. Three different algorithms for transforming the original SCP-signal into a feedback-signal have been developed and were compared in a controlled outcome study. With the optimal feedback method subjects were able to produce cortical positivity and negativity on command after three sessions. Increases and decreases of negativity of up to 20 microV were also achieved. Therefore a simple and portable PC-based device for the clinical application of SCP-biofeedback is now available.

Adult↗

PubMed1992

[Modification of autoregulation of intrinsic physical processes in field-dependent subjects: a study of performance in heart rate biofeedback].

Witkin, the founder of the concept of "field dependence", assumed that there is a relationship between field dependence and body perception. However, this hypothesis was never investigated experimentally in a well-controlled study. Twenty healthy subjects learned to increase and decrease their heart rate dependent upon two discriminative stimuli. In order to increase and decrease their heart rate they received exteroceptive feedback (movements of a rocket-ship on a video screen). Each trial lasted 6 s. The distance of the rocket-ship from a certain point indicated the amount of the achieved increase or decrease. Field dependent subjects scoring higher in field dependency as measured by the Embedded Figures Test were poorer at heart rate control on feedback and transfer trials (test trials with feedback removed) than were subjects scoring low in field dependency. This result may be of therapeutic interest in the application of behavioral medicine to psychosomatic and psychiatric disorders.

Adult↗