The cerebellum monitors errors and entrains executive networks.

Frontal midline θ (Fmθ) activity occurs in medial prefrontal cortices (mPFC), when expected and actual outcomes conflict. Cerebellar forward models could inform the mPFC about this mismatch. To verify this hypothesis we correlated the mPFC activation during a visuomotor tracking task (VM) with performance accuracy, in control and cerebellum-lesioned participants. Additionally, purely visual (V), motor (M) and a motor plus visual tasks (V + M) were performed. An Independent Component, with a mid-frontal topography scalp map and equivalent dipole location in the dorsal anterior cingulate cortex accounted for Fmθ. In control participants Fmθ power increased during VM, when the error level crossed a threshold, but not during V + M, M and V. This increase scaled with tracking error. Fmθ power failed to increase during VM in cerebellar participants, even at highest tracking errors. Thus, in control participants, activation of mPFC is induced when a continuous monitoring effort for online error detection is required. The presence of a threshold error for enhancing Fmθ, suggests the switch from an automatic to an executive tracking control, which recruits the mPFC. Given that the cerebellum stores forward models, the absence of Fmθ increases during tracking errors in cerebellar participants indicates that cerebellum is necessary for supplying the mPFC with prediction error-related information. This occurs when automatic control falters, and a deliberate correction mechanism needs to be triggered. Further studies are needed to verify if this alerting function also occurs in the context of the other cognitive and non-cognitive functions in which the cerebellum is involved.

Objective and automatic classification of Parkinson disease with Leap Motion controller.

BACKGROUND: The main objective of this paper is to develop and test the ability of the Leap Motion controller (LMC) to assess the motor dysfunction in patients with Parkinson disease (PwPD) based on the MDS-UPDRSIII exercises. Four exercises (thumb forefinger tapping, hand opening/closing, pronation/supination, postural tremor) were used to evaluate the characteristics described in MDS-UPDRSIII. Clinical ratings according to the MDS/UPDRS-section III items were used as target. For that purpose, 16 participants with PD and 12 healthy people were recruited in Ospedale Cisanello, Pisa, Italy. The participants performed standardized hand movements with camera-based marker. Time and frequency domain features related to velocity, angle, amplitude, and frequency were derived from the LMC data. RESULTS: Different machine learning techniques were used to classify the PD and healthy subjects by comparing the subjective scale given by neurologists against the predicted diagnosis from the machine learning classifiers. Feature selection methods were used to choose the most significant features. Logistic regression (LR), naive Bayes (NB), and support vector machine (SVM) were trained with tenfold cross validation with selected features. The maximum obtained classification accuracy with LR was 70.37%; the average area under the ROC curve (AUC) was 0.831. The obtained classification accuracy with NB was 81.4%, with AUC of 0.811. The obtained classification accuracy with SVM was 74.07%, with AUC of 0.675. CONCLUSIONS: Results revealed that the system did not return clinically meaningful data for measuring postural tremor in PwPD. In addition, it showed limited potential to measure the forearm pronation/supination. In contrast, for finger tapping and hand opening/closing, the derived parameters showed statistical and clinical significance. Future studies should continue to validate the LMC as updated versions of the software are developed. The obtained results support the fact that most of the set of selected features contributed significantly to classify the PwPD and healthy subjects.

Italian standardization of the Apples Cancellation Test.

Hemispatial neglect due to right parieto-temporo-frontal lesions has a negative impact on the success of rehabilitation, resulting in poor functional gain. Recent research has shown that different types of neglect can impact in a different way on rehabilitation outcomes. The availability of a sensitive test, useful for distinguishing egocentric and allocentric forms of neglect, may be clinically important as all current clinical instruments fail to distinguish between these forms of disturbance, yet they differentially predict outcome. The Apples Test is a new instrument useful to evaluate both egocentric and allocentric forms of neglect. In order to establish Italian norms for this diagnostic instrument the test was administered to a sample of 412 healthy people of both genders (201 M and 211 F), aged from 20 to 80 years enrolled from 14 different rehabilitation centers in Italy. Based on the data, we established pathological performance cut-offs for the accuracy score (total omission errors), the asymmetry score for egocentric neglect (omission error difference), the asymmetry score for allocentric neglect (commission error difference) and execution time. The usefulness of the Apples Test for diagnostic purposes is illustrated by presenting three patients with different forms of neglect (egocentric, allocentric and mixed neglect).

Quantitative EEG analysis in minimally conscious state patients during postural changes.

Mobilization and postural changes of patients with cognitive impairment are standard clinical practices useful for both psychic and physical rehabilitation process. During this process, several physiological signals, such as Electroen-cephalogram (EEG), Electrocardiogram (ECG), Photopletysmography (PPG), Respiration activity (RESP), Electrodermal activity (EDA), are monitored and processed. In this paper we investigated how quantitative EEG (qEEG) changes with postural modifications in minimally conscious state patients. This study is quite novel and no similar experimental data can be found in the current literature, therefore, although results are very encouraging, a quantitative analysis of the cortical area activated in such postural changes still needs to be deeply investigated. More specifically, this paper shows EEG power spectra and brain symmetry index modifications during a verticalization procedure, from 0 to 60 degrees, of three patients in Minimally Consciousness State (MCS) with focused region of impairment. Experimental results show a significant increase of the power in ß band (12 - 30 Hz), commonly associated to human alertness process, thus suggesting that mobilization and postural changes can have beneficial effects in MCS patients.

EEG complexity drug-induced changes in disorders of consciousness: a preliminary report.

The goal of this work is to investigate EEG (ElectroEncephaloGram) dynamics after drug intake in patients being in states of Disorders Of Consciousness (DOC) after brain injury. Four patients were involved in the study. All the patients exhibit cerebral lesions located in the same anatomical region. Two nonlinear indexes, such as Lempel-Ziv Complexity (LZC) and Approximate Entropy (ApEn), along with power spectra, were calculated for EEG signals gathered from electrodes placed on both injured and non-injured regions. Experimental results show that after drug administration the two nonlinear indexes calculated from EEG taken from injured regions increase (p < 0.001) while power spectra decrease or remain unchanged. These results do not pretend to draw conclusions about consciousness level either suggest promising therapeutical treatments, but represent only an experimental evidence about the change in the EEG complexity after drug administration.

Spontaneous blinking behaviour in persistent vegetative and minimally conscious states: relationships with evolution and outcome.

There is evidence that spontaneous blinking correlates with cognitive functions. This arises from the observation that blinking rate (BR) is modulated by arousal levels, basic cognitive processes (e.g., attention, information processing, memory, etc.) and more complex cognitive functions (e.g., reading, speaking, etc.). The aim of this work was to test the role of BR evaluation in the assessment of cognitive network functioning in awake patients with consciousness deficits. Thirteen patients were recruited for the study, and were assessed by the Glasgow coma scale (GCS) and Glasgow outcome scale (GOS) on admittance and discharge, respectively. A level of cognitive functioning scale (LCFS) score was assigned at every change in awareness or at least every 2 weeks. At the same time as the clinical tests, the BR was observed for a 5-min period. Ten healthy subjects, observed throughout three non-consecutive days, formed the control group. The BR underwent a different temporal behaviour in the two diagnostic categories. In the persistent vegetative state (PVS) group it remained stable throughout time and linked with the clinical conditions of the patients; whereas in the non-persistent vegetative state (NPVS) group it decreased over time as the cognitive conditions improved. Moreover, a strong inverse correlation was found between overall BR values and LCFS scores. We have concluded that the blinking behaviour changes manifested in PVS and NPVS patients reflect different evolution phases of a cholinergic-dopaminergic imbalance, and that a reduced BR characterizes the early stages of consciousness recovery.

A protocol for the assessment of 3D movements of the head in persons with cervical dystonia.

OBJECTIVE: To design and test a protocol for the assessment of neck movements in patients affected by cervical dystonia by using an electromagnetic system. This approach could overcome the limits of the current assessment scales in this specific field. BACKGROUND: Initial assessment and function recovery during treatments are diagnosed by the clinician using outcome scales which present many drawbacks in terms of easiness of use, sensitivity, and reliability. DESIGN: A three-dimensional motion analysis system was used to record six different head movements. METHODS: Six able-bodied subjects and 10 subjects affected by cervical dystonia participated in this study. For the different head movements three kinematic parameters (a symmetry index and two indexes related to the reduction of the range of motion) have been extracted in order to compare the performance of able-bodied and disabled persons. RESULTS: The features selected allowed highlighting of the differences between able-bodied and disabled subjects for the degrees of freedom of the neck. CONCLUSIONS: Using a motion analysis system, three kinematic features were extracted from head movements. They seem to allow a more objective assessment of the disability and a more appropriated strategy for the management of patients affected by cervical dystonia.

Impaired agonists recruitment during voluntary arm movements in patients affected by spasmodic torticollis.

We have investigated the electromyographic (EMG) and kinematic characteristics of horizontal arm extension movements in patients affected by idiopathic cervical dystonia (ICD) as well as in normal subjects. In spite of the lack of an overt dystonic involvement of the muscles acting at upper arm level, all these patients were considerably bradykinetic. Although the degree of bradykinesia observed was comparable to that previously reported for the body segment directly affected by this patholgy (21,15,8), the EMG analysis of the agonist muscles indicated a specific pathophysiological mechanism. In particular, the recruitment of the posterior deltoid (pD) in ICD patients was severely impaired within the initial phase (130 ms) of the movement. On the other hand, within the same time span, the activation of the mD, a muscle that plays a more important postural role than the pD, was not significantly different between patients and normal subjects. This reduced recruitment in the initial phase of the AG1 appears responsible of the slowness of voluntary movements.

The relation between EMG activity and kinematic parameters strongly supports a role of the action tremor in parkinsonian bradykinesia.

The kinematics characteristics of an upper arm extension of large amplitude (90 degrees) performed in the horizontal plane and the simultaneous activity of the shoulder muscles were recorded in 12 parkinsonian patients and in six normal control subjects. The movement, triggered by an acoustic "go" signal, was preceded by an isometric adduction. Within the whole population of individuals (n = 18) a strong, positive correlation was observed between the root mean square value of agonist EMG activity, evaluated during the acceleration phase of the movement, and both peak velocity and acceleration. In six patients tremor bursts at the frequency of 8-14 Hz (action tremor) were observed during the movement phase in the anterior, middle, and posterior deltoid: all these patients showed low root mean square values and were bradykinetic with respect to the control subjects. The remaining six patients did not show this action tremor during the movement phase. All but one had an agonist activation of normal duration and amplitude, showed high root mean square values, and performed well in the range of control subjects. We conclude that the inability to suppress the activity of pathological oscillator(s) responsible for the action tremor plays a fundamental role in the bradykinesia associated with Parkinson's disease.

Muscle modifications in Parkinson's disease: myoelectric manifestations.

The muscle changes occurring in Parkinson's disease (PD) may come about as a consequence of the modified pattern of motor unit activation and rigidity, which are characteristic of the disease. A tendency towards hypertrophy of type I fibers and, in some instances, atrophy of type II fibers has been observed. Fourteen patients affected by PD and 10 age-matched controls were studied in order to investigate these muscle changes. We indirectly evaluated muscle modifications by measuring muscle fiber conduction velocity (CV) and median frequency (MDF) of the power spectrum using automatic analysis of surface EMG. The tibialis anterior muscle was selected for the study of contractions electrically induced by 35 Hz pulse trains lasting 30 s; the myoelectric signal was detected using the 4-bar electrode technique described by Broman et al. (Broman, H., Bilotto, G. and De Luca, C.J. Myoelectric signal conduction velocity and spectral parameters: influence of force and time. J. Appl. Physiol., 1985, 58: 1428-1437). Muscle biopsy specimens were obtained in 4 PD patients by surgical excision at the site where the EMG recording electrode had been placed. The main difference observed between PD subjects and controls was the rate of change of MDF and CV during the course of stimulated contraction; patients with PD sustained a smaller fatigue related decrease in both parameters compared to controls. According to our histological data, this result can be explained by a type I fiber percentage which accounts for 79% of the myofiber population on average. As expected, the CV basal values correlated directly with type I fiber diameter. These data suggest that non-invasive surface EMG techniques are useful in assessing the modifications of muscle characteristics that are observed in PD patients and for analyzing some aspects of the peripheral fatigue in this disease.