Neurofeedback learning modifies the incidence rate of alpha spindles, but not their duration and amplitude

Abstract

Although the first experiments on alpha-neurofeedback date back nearly six decades ago, when Joseph Kamiya reported successful operant conditioning of alpha-rhythm in humans, the effectiveness of this paradigm in various experimental and clinical settings is still a matter of debate. Here, we investigated the changes in EEG patterns during a continuously administered neurofeedback of P4 alpha activity. Two days of neurofeedback training were sufficient for a significant increase in the alpha power to occur. A detailed analysis of these EEG changes showed that the alpha power rose because of an increase in the incidence rate of alpha episodes, whereas the amplitude and the duration of alpha oscillations remained unchanged. These findings suggest that neurofeedback facilitates volitional control of alpha activity onset, but alpha episodes themselves appear to be maintained automatically with no volitional control -a property overlooked by previous studies that employed continuous alpha-power neurofeedback. We propose that future research on alpha neurofeedback should explore reinforcement schedules based on detection of onsets and offsets of alpha waves, and employ these statistics for exploration and quantification of neurofeedback induced effects.

Short-Delay Neurofeedback Facilitates Training of the Parietal Alpha Rhythm

“…As with a simple linear model, we found that all NFB conditions had training dynamics that was significantly different from that observed in FBMock condition. Interestingly, FB0 vs. FBMock t-statistics profile is characterized by the In our previous study with a relatively short and fixed NFB latency of 360 ms [41], we observed NFB-evoked changes in the incidence rate of alpha bursts but not in their amplitude and duration. Intriguingly, this observation that casts alpha-band bursts as structural units of alpha activity whose characteristics change during NFB-induced neural plasticity is consistent with the results of [54] where importance was highlighted of the discrete beta-spindles for motor control in several species.…”

“…First, alpha rhythm is one of the most prominent and most responsive to training brain rhythms [36], [1], [12], [19], [21], [61]. According to the existing literature and our own results [41], parietal alpha rhythm easy to isolate (in contrast to the sensorimotor rhythm, for example) and is easy to train with NFB practically in all subjects. Moreover, NFB that is based on the parietal alpha rhythms has been suggested as the approach to gaining a range of functional improvements, including improvements in cognition [61], [1], [19], attention [4], [39], [40], [8], working memory [11], [67], mood [42], [13], [43], and relaxation [5].…”

“…Following the methodology of our previous study [41], for all four conditions, we analyzed the time course of burst characteristics, including incidence rate, amplitude, and duration. Alpha bursts extracted with simple thresholding from the envelope of the alpha-band filtered P4 time course, see Figure 7.…”

Towards Zero-Latency Neurofeedback

“…Typical NFB settings utilize such recording methods as EEG, magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) [1]. Aided by NFB, subjects obtain access to neural signals that they are normally unaware of, and could use these signals in various ways [1], [2], [3], [4]. Steps of NFB operation include extraction of features of interest from neural activity, their transformation into a signal suitable for the user, and delivery of feedback to the subject using one of sensory modalities, for example vision, hearing or tactile sensation.…”

“…In a recent study [4] examined the changes in temporal structure of EEG induced by NFB. EEG alpha rhythm was recorded over P4, and mean power of this signal was provided to the subjects via visual feedback.…”