Brigitte Rockstroh

The cerebellum contributes to mental skills

The cerebellum is known to play a role in simple associative motor learning in animals. It has recently been suggested that the cerebellum might also contribute to cognitive abilities in humans. Therefore 5 patients with either cerebellar lesions or atrophy were compared with 10 controls on a range of intellectual and learning abilities

Biofeedback of slow cortical potentials. I

An experiment was performed to investigate the self-regulation of slow cortical potentials (SCP) found in a previous study (Elbert et al. 1979). Seventeen subjects received continuous visual feedback of their actual cortical shift perceptible as a rocket moving across a TV-screen during intervals of 6 sec; subjects had to direct the rocket into one of two goals representing more or less cortical negativity, depending on the pitch of two signal tones. Within two identical experimental sessions feedback trials alternated with test trials without feedback. Highly significant differences of SCP between the two required polarities were demonstrated. The most pronounced differences were observed during test trials without feedback of the second session in which a positive shift below baseline level occurred when positivity (or less negativity) was required.

Removal of ocular artifacts from the EEG--a biophysical approach to the EOG.

The present paper describes the propagation of ocular potentials across the scalp on a biophysical basis. It is concluded that 3 EOG derivations (two for EEG records along the midline) are generally necessary to account for ocular disturbances in the EEG. The inadequacy of many methods suggested for EOG artifact control may be due to the false assumption that just one EOG derivation provides enough information to remove ocular potentials from any EEG recording along the mid(-sagittal) line. A comparison of compensation with one or with two EOG derivations is described for a data set of slow brain potentials. A frequency dependence of the ocular influence cannot be neglected, if fast and slow EOG activities have to be removed. The present considerations should allow a more theoretically based decision of the EOG correction method necessary for a certain data set.

Effects of the anticonvulsant benzodiazepine clonazepam on event-related brain potentials in humans☆

The effects of the benzodiazepine clonazepam (a drug used as anticonvulsant) on event-related brain potentials were investigated in healthy human subjects. Thirty-six male student volunteers (mean age 30 years) received clonazepam or a placebo in a double-blind setting. VEPs (visual evoked potentials) were obtained from the standard checkerboard reversal procedure; AEPs (auditory evoked potentials) and slow cortical potentials (CNV) were measured during a 2-stimulus reaction time paradigm, in which the quality of the acoustic S1 signalled whether the acoustic S2 would follow after 2 sec or after 6 sec. Each S2 requested a speeded button press. Compared to placebo, clonazepam significantly reduced P100 amplitude of the VEP and the amplitudes of the AEP components N1 and P3. On the other hand, clonazepam boosted the development of a distinct N2 which was not apparent in placebo subjects. The CNV was significantly reduced and reaction time increased under clonazepam compared to placebo. Specific versus non-specific damping effects of the benzodiazepine are discussed, comparing the present result with the pattern of ERP effects of the anticonvulsant carbamazepine that had been obtained using the same experimental paradigms.

Operant control of EEG and event-related and slow brain potentials.

Research on operant control of brain potentials is reviewed. From single-unit firing and spontaneous EEG activity to event-related potentials such as sensory and pain evoked potentials, and slow potential shifts, most of the aspects of electrical brain activity have been investigated. Results produced by conditioning of spontaneous EEG oscillations (alpha and theta) dampened the early enthusiasm: e.g., no increase above baseline levels could be achieved and no reliable behavioral effects became manifest. Evidence accumulates, however, that operant conditioning of the sensorimotor rhythm (12–15 Hz) may lead to successful self-regulation and that epileptic patients may profit from the training. First steps in the conditioning of brainstem, as well as pain evoked potentials suggest that self-regulation of EPs can be achieved by adequate biofeedback procedures. If some of the observed behavioral effects prove to be stable, the therapeutic usefulness seems to be within reach. A comparable progress has been achieved for the operant control of slow potentials (DC-shifts across seconds). Biofeedback procedures have been used successfully as a scientific tool to achieve systematic variations on a psychological level and to record psychological covariations. This method may provide insights into the behavioral meaning of electrical brain activity.

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.

EEG and slow cortical potentials in anticipation of mental tasks with different hemispheric involvement

Mental arithmetic is supposed to be processed by the left hemisphere, while pattern matching has been considered to be processed by the right hemisphere. These different mental tasks were presented to 16 right-handed male subjects. As a variable task difficulty was varied for the two task categories. The task presentations were preceded by 6 sec warning stimuli which indicated the level of difficulty of the task. EEG and slow cortical potentials (SCPs) were recorded from temporal and precentral leads of both hemispheres. The reference was noncephalic. During the anticipation interval beta-activity was enhanced above the hemisphere primarily involved in the particular task. SCPs failed to show a comparable clear pattern. A late negative component showed task-dependent asymmetries prior to easy tasks, but not prior to difficult tasks.

Clinical-Psychological Treatment of Epileptic Seizures: A Controlled Study

One possible strategy in the development of clinical-psychological treatments lies in the study of the biological and psychological mechanisms underlying effective medical remedies, and to “model” the behavioural therapy upon these processes. We ourselves, for instance, have studied the orthopaedic treatment of scoliosis and kyphosis with supportive corsetry, and have shown that a learning-theory mechanism, rather than a passive support function, accounts for the positive effects of such corsets: Postural changes involving curvature of the spine result in a contingent pain stimulus because of the increased contact between particular parts of the body and the corset. This pain stimulus works as a continuous punishment for incorrect posture, that the patient can escape by making appropriate postural adjustments. On the basis of this analysis, we developed a “psychological corset” that achieved the same effects through positive reinforcement, without involving pain stimuli (Dworkin et al., 1985).

BIOFEEDBACK OF EVENT-RELATED SLOW POTENTIALS OF THE BRAIN

Abstract A biofeedback paradigm was developed for self-regulation of cortical DC-shifts. Subjects received continuous visual feedback of their actual DC-shift during six sec. intervals. Feedback trial series alternated with transfer test trial series. Several studies demonstrated that subjects are able to achieve cortical self-regulation which is maintained and even improved in transfer test trials. This method is used to investigate the covariation of DC-shifts and performance in reaction time tasks, mental tasks and signal detection by varying DC-shifts systematically. The procedure was also applied to different patient groups to test the functional significance of distinct brain regions and to explore deficits in patient groups.

The Effects of Self-Regulation of Slow Cortical Potentials on Performance in a Signal Detection Task

Results from research on slow cortical potentials, especially CNV research, suggest that attention may be increased with increased cortical negative shifts. The present study investigates the relationship between performance in a signal detection task and slow cortical potentials. Cortical shifts were varied by means of a biofeedback procedure.22 subjects received continuous visual feedback or their slow cortical potentials (SCP) during intervals of 6 sec, 11 yoked control subjects received “false feedback” of the SCP of a matched experimental partner. Minimal changes of the feedback stimulus presented for 100 msec at different times during the feedback interval served as signals to be detected. The experiment consisted of 240 trials.Experimental subjects learned to shift their cortical level towards more or less negativity or positivity depending on the frequency of a signal tone. Mean differences were, however, small (5 >iV) compared to previous results on self-regulation of SCP. All subjects showed a P...