CNV
Research Papers
Neurofeedback of slow cortical potentials: neural mechanisms and feasibility of a placebo-controlled design in healthy adults
To elucidate basic mechanisms underlying neurofeedback we investigated neural mechanisms of training of slow cortical potentials (SCPs) by considering EEG- and fMRI. Additionally, we analyzed the feasibility of a double-blind, placebo-controlled design in NF research based on regulation performance during treatment sessions and self-assessment of the participants. Twenty healthy adults participated in 16 sessions of SCPs training: 9 participants received regular SCP training, 11 participants received sham feedback. At three time points (pre, intermediate, post) fMRI and EEG/ERP-measurements were conducted during a continuous performance test (CPT). Performance-data during the sessions (regulation performance) in the treatment group and the placebo group were analyzed. Analysis of EEG-activity revealed in the SCP group a strong enhancement of the CNV (electrode Cz) at the intermediate assessment, followed by a decrease back to baseline at the post-treatment assessment. In contrast, in the placebo group a continuous but smaller increase of the CNV could be obtained from pre to post assessment. The increase of the CNV in the SCP group at intermediate testing was superior to the enhancement in the placebo group. The changes of the CNV were accompanied by a continuous improvement in the test performance of the CPT from pre to intermediate to post assessment comparable in both groups. The change of the CNV in the SCP group is interpreted as an indicator of neural plasticity and efficiency while an increase of the CNV in the placebo group might reflect learning and improved timing due to the frequent task repetition. In the fMRI analysis evidence was obtained for neuronal plasticity. After regular SCP neurofeedback activation in the posterior parietal cortex decreased from the pre- to the intermediate measurement and increased again in the post measurement, inversely following the U-shaped increase and decrease of the tCNV EEG amplitude in the SCP-trained group. Furthermore, we found a localized increase of activity in the anterior cingulate cortex (ACC). Analyses of the estimation of treatment assignment by the participants indicate feasibility of blinding. Participants could not assess treatment assignment confidently. Participants of the SCP-group improved regulation capability during treatment sessions (in contrast to the participants of the placebo-group), although regulation capability appeared to be instable, presumably due to diminished confidence in the training (SCP- or sham-training). Our results indicate that SCP training in healthy adults might lead to functional changes in neuronal circuits serving cognitive preparation even after a limited number of sessions.
View Full Paper →Neurofeedback for Adult Attention-Deficit/Hyperactivity Disorder: Investigation of Slow Cortical Potential Neurofeedback—Preliminary Results
Attention deficit/hyperactivity disorder (ADHD) is characterized by symptoms of inattention, impulsivity, and hyperactivity. Compared to ADHD in children, only a few studies have investigated ADHD in an adult population, and even less have investigated new forms of treatment such as neurofeedback. Neurofeedback has been applied effectively in various areas, especially in the treatment of children with ADHD, and symptom improvements were associated with increased amplitude of the contingent negative variation (CNV). This study investigated if any behavioral and electrophysiological changes reflected in the CNV can be observed after 15 sessions of SCP neurofeedback training. Furthermore, a comparison of CNV amplitude in adults with ADHD and a healthy control group was conducted. Continuous 22-channel EEG was acquired from 10 adults who met DSM-IV criteria for ADHD and 8 matched healthy controls. EEG recordings were collected pre/midtreatment and included resting EEG, P300, and CNV tasks as well as ADHD behavioral questionnaires. The adult ADHD group received 15 sessions of SCP training at Cz (referenced to A1, ground A2). The control group only underwent the EEG recording. After 15 sessions of SCP-training a significant improvement in self-ratings of ADHD symptoms was reported. In addition, a trend in increasing CNV mean amplitude was observed after training. A significant difference in baseline CNV between the adult ADHD group and the healthy control group was observed. These results give a promising outlook to the outcome after the completion of 30 sessions of SCP training. The differences in CNV amplitude between the ADHD group and healthy controls are in line with other studies about adult ADHD and CNV. This supports the idea of impaired self-regulation in adult ADHD. The behavioral improvements and increase in CNV after SCP training suggests that SCP training has a positive effect on adult ADHD symptoms and their origin.
View Full Paper →Slow cortical potential neurofeedback in attention deficit hyperactivity disorder: is there neurophysiological evidence for specific effects?
This study compared changes in quantitative EEG (QEEG) and CNV (contingent negative variation) of children suffering from ADHD treated by SCP (slow cortical potential) neurofeedback (NF) with the effects of group therapy (GT) to separate specific from non-specific neurophysiological effects of NF. Twenty-six children (age: 11.1 ± 1.15 years) diagnosed as having ADHD were assigned to NF (N = 14) or GT (N = 12) training groups. QEEG measures at rest, CNV and behavioral ratings were acquired before and after the trainings and statistically analyzed. For children with ADHD-combined type in the NF group, treatment effects indicated a tendency toward improvement of selected QEEG markers. We could not find the expected improvement of CNV, but CNV reduction was less pronounced in good NF performers. QEEG changes were associated with some behavioral scales. Analyses of subgroups suggested specific influences of SCP training on brain functions. To conclude, SCP neurofeedback improves only selected attentional brain functions as measurable with QEEG at rest or CNV mapping. Effects of neurofeedback including the advantage of NF over GT seem mediated by both specific and non-specific factors.
View Full Paper →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.
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