Oscillatory Activity In Beta Band Research Articles

Beta drives brain beats.

OPINION article Front. Syst. Neurosci., 27 August 2014 Volume 8 - 2014 | https://doi.org/10.3389/fnsys.2014.00155

Encoding of sequence boundaries in the subthalamic nucleus of patients with Parkinson's disease.

Sequential behaviour is widespread not only in humans but also in animals, ranging in different degrees of complexity from locomotion to birdsong or music performance. The capacity to learn new motor sequences relies on the integrity of basal ganglia-cortical loops. In Parkinson's disease the execution of habitual action sequences as well as the acquisition of novel sequences is impaired partly due to a deficiency in being able to generate internal cues to trigger movement sequences. In addition, patients suffering from Parkinson's disease have difficulty initiating or terminating a self-paced sequence of actions. Direct recordings from the basal ganglia in these patients show an increased level of beta (14-30 Hz) band oscillatory activity associated with impairment in movement initiation. In this framework, the current study aims to evaluate in patients with Parkinson's disease the neuronal activity in the subthalamic nucleus related to the encoding of sequence boundaries during the explicit learning of sensorimotor sequences. We recorded local field potential activity from the subthalamic nucleus of 12 patients who underwent deep brain stimulation for the treatment of advanced Parkinson's disease, while the patients in their usual medicated state practiced sequences of finger movements on a digital piano with corresponding auditory feedback. Our results demonstrate that variability in performance during an early phase of sequence acquisition correlates across patients with changes in the pattern of subthalamic beta-band oscillations; specifically, an anticipatory suppression of beta-band activity at sequence boundaries is linked to better performance. By contrast, a more compromised performance is related to attenuation of beta-band activity before within-sequence elements. Moreover, multivariate pattern classification analysis reveals that differential information about boundaries and within-sequence elements can be decoded at least 100 ms before the keystroke from the amplitude of oscillations of subthalamic nucleus activity across different frequency bands, not just from the beta-band. Additional analysis was performed to assess the strength of how much the putative signal encoding class of ordinal position (boundaries, within-sequence elements) is reflected in each frequency band. This analysis demonstrates that suppression of power in the beta-band contains the most class-related information, whereas enhancement of gamma band (31-100 Hz) activity is the second main contributor to the encoding. Our findings support the hypothesis that subthalamic nucleus-mediated gating of salient boundary elements during sequence encoding may be a prerequisite for the adequate acquisition of action sequences and the transition to habitual behaviour.

Beat-induced fluctuations in auditory cortical beta-band activity: using EEG to measure age-related changes.

People readily extract regularity in rhythmic auditory patterns, enabling prediction of the onset of the next beat. Recent magnetoencephalography (MEG) research suggests that such prediction is reflected by the entrainment of oscillatory networks in the brain to the tempo of the sequence. In particular, induced beta-band oscillatory activity from auditory cortex decreases after each beat onset and rebounds prior to the onset of the next beat across tempi in a predictive manner. The objective of the present study was to examine the development of such oscillatory activity by comparing electroencephalography (EEG) measures of beta-band fluctuations in 7-year-old children to adults. EEG was recorded while participants listened passively to isochronous tone sequences at three tempi (390, 585, and 780 ms for onset-to-onset interval). In adults, induced power in the high beta-band (20–25 Hz) decreased after each tone onset and rebounded prior to the onset of the next tone across tempo conditions, consistent with MEG findings. In children, a similar pattern was measured in the two slower tempo conditions, but was weaker in the fastest condition. The results indicate that the beta-band timing network works similarly in children, although there are age-related changes in consistency and the tempo range over which it operates.

Frequency domain beamforming of magnetoencephalographic beta band activity in epilepsy patients with focal cortical dysplasia

Spike-based magnetoencephalography (MEG) source localization is an established method in the presurgical evaluation of epilepsy patients. Focal cortical dysplasias (FCDs) are associated with focal epileptic discharges of variable morphologies in the beta frequency band in addition to single epileptic spikes. Therefore, we investigated the potential diagnostic value of MEG-based localization of spike-independent beta band (12-30Hz) activity generated by epileptogenic lesions. Five patients with FCD IIB underwent MEG. In one patient, invasive EEG (iEEG) was recorded simultaneously with MEG. In two patients, iEEG succeeded MEG, and two patients had MEG only. MEG and iEEG were evaluated for epileptic spikes. Two minutes of iEEG data and MEG epochs with no spikes as well as MEG epochs with epileptic spikes were analyzed in the frequency domain. MEG oscillatory beta band activity was localized using Dynamic Imaging of Coherent Sources. Intralesional beta band activity was coherent between simultaneous MEG and iEEG recordings. Continuous 14Hz beta band power correlated with the rate of interictal epileptic discharges detected in iEEG. In cases where visual MEG evaluation revealed epileptic spikes, the sources of beta band activity localized within <2cm of the epileptogenic lesion as shown on magnetic resonance imaging. This result held even when visually marked epileptic spikes were deselected. When epileptic spikes were detectable in iEEG but not MEG, MEG beta band activity source localization failed. Source localization of beta band activity has the potential to contribute to the identification of epileptic foci in addition to source localization of visually marked epileptic spikes. Thus, this technique may assist in the localization of epileptic foci in patients with suspected FCD.

Convergent BOLD and Beta-Band Activity in Superior Temporal Sulcus and Frontolimbic Circuitry Underpins Human Emotion Cognition

The processing of social information in the human brain is widely distributed neuroanatomically and finely orchestrated over time. However, a detailed account of the spatiotemporal organization of these key neural underpinnings of human social cognition remains to be elucidated. Here, we applied functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) in the same participants to investigate spatial and temporal neural patterns evoked by viewing videos of facial muscle configurations. We show that observing the emergence of expressions elicits sustained blood oxygenation level-dependent responses in the superior temporal sulcus (STS), a region implicated in processing meaningful biological motion. We also found corresponding event-related changes in sustained MEG beta-band (14-30 Hz) oscillatory activity in the STS, consistent with the possible role of beta-band activity in visual perception. Dynamically evolving fearful and happy expressions elicited early (0-400 ms) transient beta-band activity in sensorimotor cortex that persisted beyond 400 ms, at which time it became accompanied by a frontolimbic spread (400-1000 ms). In addition, individual differences in sustained STS beta-band activity correlated with speed of emotion recognition, substantiating the behavioral relevance of these signals. This STS beta-band activity showed valence-specific coupling with the time courses of facial movements as they emerged into full-blown fearful and happy expressions (negative and positive coupling, respectively). These data offer new insights into the perceptual relevance and orchestrated function of the STS and interconnected pathways in social-emotion cognition.

Oscillatory activity in neocortical networks during tactile discrimination near the limit of spatial acuity

Oscillatory interactions within functionally specialized but distributed brain regions are believed to be central to perceptual and cognitive functions. Here, using human scalp electroencephalography (EEG) recordings combined with source reconstruction techniques, we study how oscillatory activity functionally organizes different neocortical regions during a tactile discrimination task near the limit of spatial acuity. While undergoing EEG recordings, blindfolded participants felt a linear three-dot array presented electromechanically, under computer control, and reported whether the central dot was offset to the left or right. The average brain response differed significantly for trials with correct and incorrect perceptual responses in the timeframe approximately between 130 and 175ms. During trials with correct responses, source-level peak activity appeared in the left primary somatosensory cortex (SI) at around 45ms, in the right lateral occipital complex (LOC) at 130ms, in the right posterior intraparietal sulcus (pIPS) at 160ms, and finally in the left dorsolateral prefrontal cortex (dlPFC) at 175ms. Spectral interdependency analysis of activity in these nodes showed two distinct distributed networks, a dominantly feedforward network in the beta band (12–30Hz) that included all four nodes and a recurrent network in the gamma band (30–100Hz) that linked SI, pIPS and dlPFC. Measures of network activity in both bands were correlated with the accuracy of task performance. These findings suggest that beta and gamma band oscillatory networks coordinate activity between neocortical regions mediating sensory and cognitive processing to arrive at tactile perceptual decisions.

Decreased beta-band activity is correlated with disambiguation of hidden figures

Insight is commonly described as sudden comprehension, sometimes called an “Aha! moment.” In everyday life, we apply the process of insight to problems that are difficult to solve at first glance or that we perceive as ambiguous; however the brain dynamics underlying the disambiguation process remains elusive. Beta-band oscillatory brain activity has been hypothesized to reflect the transition of cognitive states. To elucidate the neural mechanism of insight, we recorded electroencephalograms while subjects were presented with hidden figures followed by unambiguous, gray images. We identified oscillatory activity to detect temporal changes, and compared brain activity that occurred during a perceptual transition with activity that occurred when no perceptual transition occurred. Statistical comparison confirmed stronger beta-power decrease during perceptual transition. Source analysis indicated that the beta-power decrease was around the parietal–posterior regions, mainly in the precuneus. We propose that beta-band desynchronization in the parietal–posterior regions reflects the disambiguation process, and our findings provide additional support for the theory that beta-band activity is related to the transition of cognitive state.

Modulation of Beta Oscillations in the Subthalamic Nucleus with Prosaccades and Antisaccades in Parkinson's Disease

Increased oscillations in the beta band are thought to be related to motor symptoms of Parkinson's disease (PD). Previous studies have shown that beta-band desynchronization in the subthalamic nucleus (STN) is reduced just before and during limb movements. While the STN is part of the basal ganglia (BG)-thalamocortical circuit controlling limb movements, it is also part of the BG-brainstem projection controlling saccadic eye movements. Late-stage PD patients have deficits in saccades in addition to difficulties with limb movements arising from impaired functions of the BG. We investigated saccade-related changes in beta-band (15-30 Hz) oscillatory activities in the human STN while PD patients performed visually guided prosaccades and antisaccades, the latter requiring suppression of reflexive responses and volitional initiation of saccades. We recorded local field potentials from deep brain stimulation electrodes implanted in the STN in human PD patients 1-5 d after surgery and compared prosaccades and antisaccades with these and with limb movements. Saccade-related beta-band desynchronizations were observed just before and during saccades in all subjects, suggesting that reduction of beta-band oscillatory activity in the STN is related to preparation and execution of saccades. Furthermore, beta-band desynchronizations for antisaccades started earlier, were sustained for longer periods, were of greater magnitude, and were observed more often than prosaccades. Beta-band desynchronization in the STN may reflect the additional processes associated with suppression of reflexive responses and volitional execution of saccades in the opposite direction.

Failure of Delayed Feedback Deep Brain Stimulation for Intermittent Pathological Synchronization in Parkinson’s Disease

Suppression of excessively synchronous beta-band oscillatory activity in the brain is believed to suppress hypokinetic motor symptoms of Parkinson’s disease. Recently, a lot of interest has been devoted to desynchronizing delayed feedback deep brain stimulation (DBS). This type of synchrony control was shown to destabilize the synchronized state in networks of simple model oscillators as well as in networks of coupled model neurons. However, the dynamics of the neural activity in Parkinson’s disease exhibits complex intermittent synchronous patterns, far from the idealized synchronous dynamics used to study the delayed feedback stimulation. This study explores the action of delayed feedback stimulation on partially synchronized oscillatory dynamics, similar to what one observes experimentally in parkinsonian patients. We employ a computational model of the basal ganglia networks which reproduces experimentally observed fine temporal structure of the synchronous dynamics. When the parameters of our model are such that the synchrony is unphysiologically strong, the feedback exerts a desynchronizing action. However, when the network is tuned to reproduce the highly variable temporal patterns observed experimentally, the same kind of delayed feedback may actually increase the synchrony. As network parameters are changed from the range which produces complete synchrony to those favoring less synchronous dynamics, desynchronizing delayed feedback may gradually turn into synchronizing stimulation. This suggests that delayed feedback DBS in Parkinson’s disease may boost rather than suppress synchronization and is unlikely to be clinically successful. The study also indicates that delayed feedback stimulation may not necessarily exhibit a desynchronization effect when acting on a physiologically realistic partially synchronous dynamics, and provides an example of how to estimate the stimulation effect.

Modulation of local field potential power of the subthalamic nucleus during isometric force generation in patients with Parkinson’s disease

Investigations of local field potentials of the subthalamic nucleus of patients with Parkinson’s disease have provided evidence for pathologically exaggerated oscillatory beta-band activity (13–30Hz) which is amenable to physiological modulation by, e.g., voluntary movement. Previous functional magnetic resonance imaging studies in healthy controls have provided evidence for an increase of subthalamic nucleus blood-oxygenation-level-dependant signal in incremental force generation tasks.However, the modulation of neuronal activity by force generation and its relationship to peripheral feedback remain to be elucidated. We hypothesised that beta-band activity in the subthalamic nucleus is modulated by incremental force generation. Subthalamic nucleus local field potentials were recorded intraoperatively in 13 patients with Parkinson’s disease (37 recording sites) during rest and five incremental isometric force generation conditions of the arm with applied loads of 0–400g (in 100-g increments).Repeated measures analysis of variance (ANOVA) revealed a modulation of local field potential (LFP) power in the upper beta-band (in 24–30Hz; F(3.042)=4.693, p=0.036) and the gamma-band (in 70–76Hz; F(4)=4.116, p=0.036). Granger-causality was computed with the squared partial directed coherence and showed no significant modulation during incremental isometric force generation.Our findings indicate that the upper beta- and gamma-band power of subthalamic nucleus local field potentials are modulated by the physiological task of force generation in patients with Parkinson’s disease. This modulation seems to be not an effect of a modulation of peripheral feedback.

Basal ganglia modulation of thalamocortical relay in Parkinson's disease and dystonia

Basal ganglia dysfunction has being implied in both Parkinson's disease and dystonia. While these disorders probably involve different cellular and circuit pathologies within and beyond basal ganglia, there may be some shared neurophysiological pathways. For example, pallidotomy and pallidal Deep Brain Stimulation (DBS) are used in symptomatic treatment of both disorders. Both conditions are marked by alterations of rhythmicity of neural activity throughout basal ganglia-thalamocortical circuits. Increased synchronized oscillatory activity in beta band is characteristic of Parkinson's disease, while different frequency bands, theta and alpha, are involved in dystonia. We compare the effect of the activity of GPi, the output nuclei of the basal ganglia, on information processing in the downstream neural circuits of thalamus in Parkinson's disease and dystonia. We use a data-driven computational approach, a computational model of the thalamocortical (TC) cell modulated by experimentally recorded data, to study the differences and similarities of thalamic dynamics in dystonia and Parkinson's disease. Our analysis shows no substantial differences in TC relay between the two conditions. Our results suggest that, similar to Parkinson's disease, a disruption of thalamic processing could also be involved in dystonia. Moreover, the degree to which TC relay fidelity is impaired is approximately the same in both conditions. While Parkinson's disease and dystonia may have different pathologies and differ in the oscillatory content of neural discharge, our results suggest that the effect of patterning of pallidal discharge is similar in both conditions. Furthermore, these results suggest that the mechanisms of GPi DBS in dystonia may involve improvement of TC relay fidelity.

Effects of decision variables and intraparietal stimulation on sensorimotor oscillatory activity in the human brain.

To decide effectively, information must not only be integrated from multiple sources, but it must be distributed across the brain if it is to influence structures such as motor cortex that execute choices. Human participants integrated information from multiple, but only partially informative, cues in a probabilistic reasoning task in an optimal manner. We tested whether lateralization of alpha- and beta-band oscillatory brain activity over sensorimotor cortex reflected decision variables such as the sum of the evidence provided by observed cues, a key quantity for decision making, and whether this could be dissociated from an update signal reflecting processing of the most recent cue stimulus. Alpha- and beta-band activity in the electroencephalogram reflected the logarithm of the likelihood ratio associated with the each piece of information witnessed, and the same quantity associated with the previous cues. Only the beta-band, however, reflected the most recent cue in a manner that suggested it reflected updating processes associated with cue processing. In a second experiment, transcranial magnetic stimulation-induced disruption was used to demonstrate that the intraparietal sulcus played a causal role both in decision making and in the appearance of sensorimotor beta-band activity.

Improved efficacy of temporally non-regular deep brain stimulation in Parkinson's disease

High frequency deep brain stimulation is an effective therapy for motor symptoms in Parkinson's disease. However, the relative clinical efficacy of regular versus non-regular temporal patterns of stimulation in Parkinson's disease remains unclear. To determine the temporal characteristics of non-regular temporal patterns of stimulation important for the treatment of Parkinson's disease, we compared the efficacy of temporally regular stimulation with four non-regular patterns of stimulation in subjects with Parkinson's disease using an alternating finger tapping task. The patterns of stimulation were also evaluated in a biophysical model of the parkinsonian basal ganglia that exhibited prominent oscillatory activity in the beta frequency range. The temporal patterns of stimulation differentially improved motor task performance. Three of the non-regular patterns of stimulation improved performance of the finger tapping task more than temporally regular stimulation. In the computational model all patterns of deep brain stimulation suppressed beta band oscillatory activity, and the degree of suppression was strongly correlated with the clinical efficacy across stimulation patterns. The three non-regular patterns of stimulation that improved motor performance over regular stimulation also suppressed beta band oscillatory activity in the computational model more effectively than regular stimulation. These data demonstrate that the temporal pattern of stimulation is an important consideration for the clinical efficacy of deep brain stimulation in Parkinson's disease. Furthermore, non-regular patterns of stimulation may ameliorate motor symptoms and suppress pathological rhythmic activity in the basal ganglia more effectively than regular stimulation. Therefore, non-regular patterns of deep brain stimulation may have useful clinical and experimental applications.

Emotional Facial Expressions Modulate Pain-Induced Beta and Gamma Oscillations in Sensorimotor Cortex

Painful events in our environment are often accompanied by stimuli from other sensory modalities. These stimuli may influence the perception and processing of acute pain, in particular when they comprise emotional cues, like facial expressions of people surrounding us. In this whole-head magnetoencephalography (MEG) study, we examined the neuronal mechanisms underlying the influence of emotional (fearful, angry, or happy) compared to neutral facial expressions on the processing of pain in humans. Independent of their valence, subjective pain ratings for intracutaneous inputs were higher when pain stimuli were presented together with emotional facial expressions than when they were presented with a neutral facial expression. Source reconstruction using linear beamforming revealed pain-induced early (70-270 ms) oscillatory beta-band activity (BBA; 15-25 Hz) and gamma-band activity (GBA; 60-80 Hz) in the sensorimotor cortex. The presentation of faces with emotional expressions compared to faces with neutral expressions led to a stronger bilateral suppression of the pain-induced BBA, possibly reflecting enhanced response readiness of the sensorimotor system. Moreover, pain-induced GBA in the sensorimotor cortex was larger for faces expressing fear than for faces expressing anger, which might reflect the facilitation of avoidance-motivated behavior triggered by the concurrent presentation of faces with fearful expressions and painful stimuli. Thus, the presence of emotional cues, like facial expressions from people surrounding us, while receiving acute pain may facilitate neuronal processes involved in the preparation and execution of adequate protective motor responses.

Beta-Band Activity during Motor Planning Reflects Response Uncertainty

It has been known for many years that the power of beta-band oscillatory activity in motor-related brain regions decreases during the preparation and execution of voluntary movements. However, it is not clear yet whether the amplitude of this desynchronization is modulated by any parameter of the motor task. Here, we examined whether the degree of uncertainty about the upcoming movement direction modulated beta-band desynchronization during motor preparation. To this end, we recorded whole-head neuromagnetic signals while human subjects performed an instructed-delay reaching task with one, two, or three possible target directions. We found that the reduction of power of beta-band activity (16-28 Hz) during motor preparation was scaled relative to directional uncertainty. Furthermore, we show that the change of beta-band power correlates with the change of latency of response associated with response uncertainty. Finally, we show that the main source of beta-band desynchronization was located in the peri-Rolandic region. The results establish directional uncertainty as an important determinant of beta-band power during motor preparation and indicate that neural activity in the sensorimotor cortex during motor preparation covaries with directional uncertainty.

Fine temporal structure of beta oscillations synchronization in subthalamic nucleus in Parkinson's disease.

Synchronous oscillatory dynamics in the beta frequency band is a characteristic feature of neuronal activity of basal ganglia in Parkinson's disease and is hypothesized to be related to the disease's hypokinetic symptoms. This study explores the temporal structure of this synchronization during episodes of oscillatory beta-band activity. Phase synchronization (phase locking) between extracellular units and local field potentials (LFPs) from the subthalamic nucleus (STN) of parkinsonian patients is analyzed here at a high temporal resolution. We use methods of nonlinear dynamics theory to construct first-return maps for the phases of oscillations and quantify their dynamics. Synchronous episodes are interrupted by less synchronous episodes in an irregular yet structured manner. We estimate probabilities for different kinds of these "desynchronization events." There is a dominance of relatively frequent yet very brief desynchronization events with the most likely desynchronization lasting for about one cycle of oscillations. The chances of longer desynchronization events decrease with their duration. The observed synchronization may primarily reflect the relationship between synaptic input to STN and somatic/axonal output from STN at rest. The intermittent, transient character of synchrony even on very short time scales may reflect the possibility for the basal ganglia to carry out some informational function even in the parkinsonian state. The dominance of short desynchronization events suggests that even though the synchronization in parkinsonian basal ganglia is fragile enough to be frequently destabilized, it has the ability to reestablish itself very quickly.

Pathological subthalamic nucleus oscillations in PD: Can they be the cause of bradykinesia and akinesia?

There is growing evidence that Parkinson's disease (PD) is associated with pathological synchronous oscillatory activity in the basal ganglia. These synchronized oscillations primarily occur in the 11–30 Hz range, the so-called beta band. Studies of local field potential activity in the subthalamic nucleus (STN) of PD patients suggest that exaggerated beta band oscillatory activity can disrupt function and, in particular, may contribute to slowness of movement. It has been previously shown that the degree of beta oscillatory activity in the STN of PD patients correlates with the patients' benefit from dopaminergic medications, but not with baseline motor deficits. In a paper that was recently published in Experimental Neurology, [Kuhn A.A., Tsui A., Aziz T., Ray N., Brucke C., Kupsch A., Schneider G.H., Brown P., 2009. Pathological synchronisation in the subthalamic nucleus of patients with Parkinson's disease relates to both bradykinesia and rigidity. Exp. Neurol. 215, 380–387.] the authors further establish that the degree of suppression of beta oscillations in the STN by dopaminergic medications can predict the level of improvement in bradykinesia and rigidity but not tremor. This commentary reviews some of the recent findings on beta oscillatory activity in PD and highlights the possible role of these pathological oscillations in mediating PD symptoms.

A simultaneous MEG and intracranial EEG study of task-related brain oscillations

In an effort to find quantitative markers of attention during reading, we performed simultaneous MEG and intracranial EEG recordings of alpha, beta and gamma band oscillatory activity in an epileptic patient during attentive vs. inattentive reading. We compared the strength and spatial organization of those oscillations between the two conditions. Time-frequency analysis of intracranial EEG revealed an attention-dependant network of gamma band energy increases and alpha/beta energy suppressions in response to word presentation. MEG data were also characterized by power increases in the gamma band and power suppressions in the alpha/beta range, mirroring the intracranial effects. The agreement we found between MEG and intracranial EEG power modulations suggests that MEG can detect attention-related modulations of cortical oscillatory processes and thus provide a reliable non-invasive measure of attention during reading in individual subjects.

Multi-electrode recordings reveal enhanced beta-synchrony along the cortico-striatal axis in the rat model of parkinsonism

Recent studies in primates and patients suffering from Parkinson's disease emphasize an excessive synchronization of activity in the basal ganglia in the beta-frequency range, emerging as a network effect of dopamine depletion. The striatum, as the head end of the circuit linking cerebral cortex and basal ganglia, may be a crucial point for the emergence or/and maintenance of increased temporal coupling. To assess changes in coupling between neuronal assemblies in the cortex and the striatum following unilateral 6-hydroxydopamine lesions of midbrain dopamine neurons, we recorded unit activity and local field potentials (LFP) in lesioned and in healthy rats. Signals were acquired bilaterally from various cortical areas and the striatum of halothane-anesthetized rats. Dopamine depletion led to a significant increase of beta-band (10–20Hz) oscillatory activity (BO) in units as well as LFPs. Pronounced BO appeared in short bursts recurring with a frequency of 0.2–2Hz, accompanying irregular slow wave activity in the EEG. BO was not present during spontaneously occurring episodes of clockwork-like delta oscillations with lower amplitudes. In contrast to the global coherence of the slow waves, BO was topographically restricted to sensorimotor cortical areas, and was present neither in parietal or occipital cortices nor in the hippocampus. The oscillations were found on both hemispheres, but coherence analysis of LFPs revealed a coupling of BO only for cortico-cortical and cortico-striatal pairs of recording sites within the same hemisphere. In line with these observations, cortical unit activity was found to correlate at beta-frequencies only within, but not across the hemispheres. Interestingly, administration of the dopamine receptor agonist apomorphine suppressed BO. Taken together, our results suggest that BO emerging due to dopamine depletion prevail even during anesthesia, are restricted to sensorimotor areas and may lead to an involvement of the non-lesioned hemisphere.