Paolo Andre

Cortical source of blink-related delta oscillations and their correlation with levels of consciousness.

Recently, blink‐related delta oscillations (delta BROs) have been observed in healthy subjects during spontaneous blinking at rest. Delta BROs have been linked with continuous gathering of information from the surrounding environment, which is classically attributed to the precuneus. Furthermore, fMRI studies have shown that precuneal activity is reduced or missing when consciousness is low or absent. We therefore hypothesized that the source of delta BROs in healthy subjects could be located in the precuneus and that delta BROs could be absent or reduced in patients with disorders of consciousness (DOC). To test these hypotheses, electroencephalographic (EEG) activity at rest was recorded in 12 healthy controls and nine patients with DOC (four vegetative states, and five minimally conscious states). Three‐second‐lasting EEG epochs centred on each blink instance were analyzed in both time‐ (BROs) and frequency domains (event‐related spectral perturbation or ERSP and intertrial coherence or ITC). Cortical sources of the maximum blink‐related delta power, corresponding to the positive peak of the delta BROs, were estimated by standardized Low Resolution Electromagnetic Tomography. In control subjects, as expected, the source of delta BROs was located in the precuneus, whereas in DOC patients, delta BROs were not recognizable and no precuneal localization was possible. Furthermore, we observed a direct relationship between spectral indexes and levels of cognitive functioning in all subjects participating in the study. This reinforces the hypothesis that delta BROs reflect neural processes linked with awareness of the self and of the environment. Hum Brain Mapp 34:2178–2189, 2013.

Spectral Parameters Modulation and Source Localization of Blink-Related Alpha and Low-Beta Oscillations Differentiate Minimally Conscious State from Vegetative State/Unresponsive Wakefulness Syndrome

Recently, the cortical source of blink-related delta oscillations (delta BROs) in resting healthy subjects has been localized in the posterior cingulate cortex/precuneus (PCC/PCu), one of the main core-hubs of the default-mode network. This has been interpreted as the electrophysiological signature of the automatic monitoring of the surrounding environment while subjects are immersed in self-reflecting mental activities. Although delta BROs were directly correlated to the degree of consciousness impairment in patients with disorders of consciousness, they failed to differentiate vegetative state/unresponsive wakefulness syndrome (VS/UWS) from minimally conscious state (MCS). In the present study, we have extended the analysis of BROs to frequency bands other than delta in the attempt to find a biological marker that could support the differential diagnosis between VS/UWS and MCS. Four patients with VS/UWS, 5 patients with MCS, and 12 healthy matched controls (CTRL) underwent standard 19-channels EEG recordings during resting conditions. Three-second-lasting EEG epochs centred on each blink instance were submitted to time-frequency analyses in order to extract the normalized Blink-Related Synchronization/Desynchronization (nBRS/BRD) of three bands of interest (low-alpha, high-alpha and low-beta) in the time-window of 50–550 ms after the blink-peak and to estimate the corresponding cortical sources of electrical activity. VS/UWS nBRS/BRD levels of all three bands were lower than those related to both CTRL and MCS, thus enabling the differential diagnosis between MCS and VS/UWS. Furthermore, MCS showed an intermediate signal intensity on PCC/PCu between CTRL and VS/UWS and a higher signal intensity on the left temporo-parieto-occipital junction and inferior occipito-temporal regions when compared to VS/UWS. This peculiar pattern of activation leads us to hypothesize that resting MCS patients have a bottom-up driven activation of the task positive network and thus are tendentially prone to respond to environmental stimuli, even though in an almost unintentional way.

Reciprocal dynamics of EEG alpha and delta oscillations during spontaneous blinking at rest: A survey on a default mode-based visuo-spatial awareness

By means of a narrowband wavelet analysis (0.5-6Hz), EEG delta event-related oscillations (EROs), both time- and phase-locked to spontaneous blinking (delta blink-related oscillations or delta BROs), have recently been demonstrated. On the basis of their spatiotemporal characteristics, delta BROs have been proposed as being involved in an automatic mechanism of maintaining awareness in a visuo-spatial context. The aim of the present study was: a) to investigate whether spontaneous blinking was also able to modulate alpha oscillations and, if so, b) whether this modulation was consistent with delta BROs, in order c) to acquire additional information for a better understanding of the cognitive phenomena underlying blinking. Using a broadband (0.5-100 Hz) continuous wavelet transform (CWT), we analysed a total of 189 three-second EEG epochs time-locked to the blinks of seven healthy volunteers. The EEG signals were submitted both to band-pass filtered cross-trial averaging (to obtain frequency-specific BROs) and to alpha event-related synchronization/desynchronization (i.e., blink-related synchronization/desynchronization, BRS/BRD). The alpha oscillations showed: a) an early BRS; b) a BRD in the same temporal window of the delta BROs and, c) a late BRS. We postulate that: a) the early BRS represents the short-term memory maintenance of the last visually perceived trace of the surroundings; b) the alpha BRD is associated with the comparison between the newly perceived image of the environment and its mnestic representation, and, lastly, c) the late BRS is connected with neuronal recovery phenomena.

Hypnotizability-related EEG alpha and theta activities during visual and somesthetic imageries.

Hypnotizability is a cognitive multidimensional trait that involves peculiar imagery characteristics. Subjects with high- (Highs) and low (Lows)-susceptibilities to hypnosis have shown different levels of skill at visual and somesthetic-guided imageries performed during upright stance. The aim of this experiment is to study the modulation of the EEG alpha and theta band amplitude during guided visual and somesthetic imageries in Highs and Lows, as these rhythms are responsive to the cognitive activities involved in mental imagery. Our results show that, at variance with standing subjects, subjects in both groups in a semi-reclined position report higher vividness and lower effort for visual than for somesthetic imagery. EEG patterns however are different between the two groups. Highs exhibit a more widespread alpha desynchronization and slightly different EEG patterns during visual and somesthetic imageries, while Lows show segregated alpha- and theta-desynchronization, without any difference between the tasks. Our results indicate that different, hypnotizability-related cognitive strategies, that are revealed by differences in EEG modulation, are responsible for the similar subjective experience associated with visual and somesthetic imageries in Highs and Lows. In addition, in both groups higher order mental representation of different sensory modalities might be subserved by a unique integrated neural network.

EEG Theta Dynamics within Frontal and Parietal Cortices for Error Processing during Reaching Movements in a Prism Adaptation Study Altering Visuo-Motor Predictive Planning.

Modulation of frontal midline theta (fmθ) is observed during error commission, but little is known about the role of theta oscillations in correcting motor behaviours. We investigate EEG activity of healthy partipants executing a reaching task under variable degrees of prism-induced visuo-motor distortion and visual occlusion of the initial arm trajectory. This task introduces directional errors of different magnitudes. The discrepancy between predicted and actual movement directions (i.e. the error), at the time when visual feedback (hand appearance) became available, elicits a signal that triggers on-line movement correction. Analysis were performed on 25 EEG channels. For each participant, the median value of the angular error of all reaching trials was used to partition the EEG epochs into high- and low-error conditions. We computed event-related spectral perturbations (ERSP) time-locked either to visual feedback or to the onset of movement correction. ERSP time-locked to the onset of visual feedback showed that fmθ increased in the high- but not in the low-error condition with an approximate time lag of 200 ms. Moreover, when single epochs were sorted by the degree of motor error, fmθ started to increase when a certain level of error was exceeded and, then, scaled with error magnitude. When ERSP were time-locked to the onset of movement correction, the fmθ increase anticipated this event with an approximate time lead of 50 ms. During successive trials, an error reduction was observed which was associated with indices of adaptations (i.e., aftereffects) suggesting the need to explore if theta oscillations may facilitate learning. To our knowledge this is the first study where the EEG signal recorded during reaching movements was time-locked to the onset of the error visual feedback. This allowed us to conclude that theta oscillations putatively generated by anterior cingulate cortex activation are implicated in error processing in semi-naturalistic motor behaviours.

Serious Game and Wearable Haptic Devices for Neuro Motor Rehabilitation of Children with Cerebral Palsy

Cerebral palsy (CP) is a group of disorders that affect the development of movement and posture, resulting in limited activities. To optimize pediatric neuro-rehabilitation and to complement conventional occupational therapies, serious game based therapies for upper limb (UL) rehabilitation have been developed or adapted for the pediatric field during recent years. In this work, we present the design and development of UL rehabilitation scenario for CP patients, based on Serious Games (SG) and enhanced by immersive virtual reality (VR) with haptic feedback to increase engagement and provide rich, congruent multi-sensory feedback during virtual interaction.

Corrigendum to "Blink-related delta oscillations in the resting-state EEG: A wavelet analysis" (Neurosci. Lett. 449 (2009) 57-60)

Subsequent recordings collected during a follow-up of our studieson blink-related EEG have not produced results overlapping thosereported in the previous paper [3]. In particular, the blink-relateddelta oscillation, that was a biphasic negative-positive waveformin the above-mentioned paper, has turned out to be reversed inpolarity (i.e., positive-negative) in the recent recordings.The only difference in the EEG data processing with respect tothe previous recordings was in the export file format: EDF (recent)vs ASCII (previous). We believe that the polarity originating fromthe EDF files (i.e., positive-negative) should be considered correct,because EEG data exported in the form of EDF files, according tothe specifications of the format itself, faithfully represent originalraw data [6,7]. On the contrary, data exported in the form of filetext (with an ASCII code) only allow reproducing signals visual-izedontherecordingdevicescreen.But,indoingso,thewaveformis reconstructed referring to an internal code, according to whichnegative values are assigned to the points situated in the inferiorpart of the picture (with respect to an equatorial line of symme-try). This poses a serious problem when the reference coordinatesof the recording device, concerning vice versa the polarity of thedeflections with respect to the isoelectric line, are such that posi-tive deflections are downward. In this case, in fact, the procedureof exporting data as ASCII files, by assigning negative values to thesamedeflections(becausetheyarereallydownwardfromaspatialpoint of view), gives rise to an error of inverted polarity. In otherwords, such a procedure preserves the graphic representation ofthe data without considering the true polarity.This would not be a problem when on-line averaged evokedpotentials with known waveform and polarity are exported (pro-vided that one reverses the polarity off-line so they match with

Role of Acupuncture in the Management of Severe Acquired Brain Injuries (sABIs)

Acupuncture therapy has been used to treat several disorders in Asian countries and its use is increasing in Western countries as well. Current literature assessed the safety and efficacy of acupuncture in the acute management and rehabilitation of patients with neurologic disorders. In this paper, the role of acupuncture in the treatment of acute severe acquired brain injuries is described, acting on neuroinflammation, intracranial oedema, oxidative stress, and neuronal regeneration. Moreover, beneficial effects of acupuncture on subacute phase and chronic outcomes have been reported in controlling the imbalance of IGF-1 hormone and in decreasing spasticity, pain, and the incidence of neurovegetative crisis. Moreover, acupuncture may have a positive action on the arousal recovery. Further work is needed to understand the effects of specific acupoints on the brain. Allegedly concurrent neurophysiological measurements (e.g., EEG) may help in studying acupuncture-related changes in central nervous system activity and determining its potential as an add-on rehabilitative treatment for patients with consciousness disorders.