Gianluigi Reni

Multimodal analysis of a sustained attention protocol: continuous performance test assessed with near infrared spectroscopy and EEG.

The aim of this work is to describe, using functional imaging techniques, the spatial and temporal distribution of neural activations ensuing from execution of cognitive functions and to find correlation in data coming from analysis modalities related to different physical properties. A 10-mm continuous performance test (CPT) was administered to a group of healthy subjects as measure of sustained attention. Images of electroencephalography (EEG) and of near infrared spectroscopy (NIRS) were recorded during the task. cerebral activations measure is obtained from the recording of quantities linked with electrical neural activity for the EEG and with change in blood oxygenation for the NIRS system. Good agreement was found between the two modalities, both showing higher activation in the middle upper frontal region and similar temporal trend. A further understanding of the superior central nervous system behavior can be achieved from combined use of both imaging modalities

Activation of the prefrontal cortex during a visual n-back working memory task with varying memory load: A near infrared spectroscopy study

We evaluated frontal brain activation during a Working Memory task with graded levels of difficulty in a group of 15 healthy subjects, by means of fNIRS technique. Brain activation (% signal change with respect to the baseline) was computed and load-related increases of blood oxygenation were found for the four different levels of task difficulty. Generalized Linear Models were applied to the data in order to evaluate the metabolic processes occurring during the mental effort and, possibly, their involvement in short term memorization. The Cognitive Failure Questionnaire was also administered in order to assess its diagnostic relevance in clinics. Results attest a monotous increase of brain oxygenation with WM load during the first half of task, persisting through the central resting period and prevailing in the left hemisphere. Decreasing WM load is also coupled with oxygenated hemoglobin decrease.

Investigation of negative BOLD responses in human brain through NIRS technique. A visual stimulation study

Despite negative blood oxygenation level dependent (BOLD) responses to visual stimuli have recently gained considerable interest, the explanation for their underlying neuronal and vascular mechanisms is still controversial. In the present study, a multimodal experimental approach is presented to shed light on the negative BOLD phenomenon in the human brain. In particular, information from functional magnetic resonance imaging (fMRI) and near infrared spectroscopy (NIRS) was integrated to confirm and gain insight into the phenomenon of negative BOLD responses (NBRs) to unpatterned intermittent photic stimulation (IPS) in healthy subjects. Eight healthy subjects participated in the study. Consistent findings emerged from the activation analysis of fMRI and NIRS data and the comparison of BOLD and hemoglobin responses at the single channel level showed that NBRs are related to a decrease in oxyhemoglobin (HbO) combined with a lower increase in deoxyhemoglobin (HHb), corresponding to a decrease in total hemoglobin (THb) and estimated cerebral blood volume (CBV). The HbO and HHb variations were significant in at least one channel in six subjects out of eight (p<0.05). The NIRS technique allowed obtaining valuable information on the vascular determinants of the NBRs, since the discrimination between HbO, HHb and THb information provided a more comprehensive view of the negative BOLD phenomenon. The within and between subject heterogeneous BOLD-Hb temporal relations pave the way to further investigations into the neurovascular properties of NBRs.

Reach and throw movement analysis with support vector machines in early diagnosis of autism

Movement disturbances play an intrinsic part in autism. Upper limb movements like reach-and-throw seem to be helpful in early identification of children affected by autism. Nevertheless few works investigate the application of classifying methods to upper limb movements. In this study we used a machine learning approach Support Vector Machine (SVM) for identifying peculiar features in reach-and-throw movements. 10 pre-scholar age children with autism and 10 control subjects performing the same exercises were analyzed. The SVM algorithm proved to be able to separate the two groups: accuracy of 100% was achieved with a soft margin algorithm, and accuracy of 92.5% with a more conservative one. These results were obtained with a radial basis function kernel, suggesting that a non-linear analysis is possibly required.

Combined behavioral and EEG power analysis in DAI improve accuracy in the assessment of sustained attention deficit.

In clinical routine, the evaluation of sustained attention is often performed by analyzing the behavioral data collected during specific tests. Such analyses are rarely accompanied by a detailed examination of the subject’s simultaneous electroencephalographic (EEG) activity, and particularly its frequency content. In this study, a group of healthy volunteers and a group of patients affected by diffuse axonal injury (DAI) were tested while performing a modified version of the Conners’ continuous performance test. A comparative study was carried out between the behavioral and neuropsychological data obtained during the task, to investigate neural activation. Spectral power was calculated for each of the recorded EEG signals, taking account of the frequency bands traditionally considered in literature. Then a compressed spectral array sequence of spectra was plotted to put into evidence the temporal modifications in the signal power spectral density, and, finally, the analysis of the rhythm variability was carried out. Evaluation of the results thus obtained shows that the two groups registered very different cerebral activation dynamics during the ongoing attentional task. Moreover, DAI patients showed mild cortical activation in the prefrontal region, spread equally throughout both brain hemispheres, while controls showed strong predominant activation of the right prefrontal area. Our findings encourage further investigations of the combined employment of tests and EEG recordings during the clinical assessment of sustained attention performance.

Single-sweep analysis using an autoregressive with exogenous input (ARX) model

Single-sweep visual evoked potential analysis would be useful in clinical electro-physiology practice because it would make possible the evaluation of transient phenomena, but recording single-sweep visual evoked potentials is difficult because of the low signal-noise ratio. To increase this ratio we used a filter based on an autoregressive with exogenous input model. We studied a group of 12 diabetic patients matched with a control group of 14 normal subjects. The model, in most cases, allowed us to extrapolate the P100 component from each single sweep of visual evoked potential. The visual evoked potential values obtained by means of averaging were not significantly different in the groups studied, but single-sweep analysis showed different distribution of the P100 component amplitude. The preliminary results of our study evidenced differences in the amplitude and latency distribution of normal and diabetic subjects, thus confirming the power of this new technique and its ability to obtain some information that is masked by the averaging method.

Removal of pulse artefact from EEG data recorded in MR environment at 3T. Setting of ICA parameters for marking artefactual components: application to resting-state data.

Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) allow for a non-invasive investigation of cerebral functions with high temporal and spatial resolution. The main challenge of such integration is the removal of the pulse artefact (PA) that affects EEG signals recorded in the magnetic resonance (MR) scanner. Often applied techniques for this purpose are Optimal Basis Set (OBS) and Independent Component Analysis (ICA). The combination of OBS and ICA is increasingly used, since it can potentially improve the correction performed by each technique separately. The present study is focused on the OBS-ICA combination and is aimed at providing the optimal ICA parameters for PA correction in resting-state EEG data, where the information of interest is not specified in latency and amplitude as in, for example, evoked potential. A comparison between two intervals for ICA calculation and four methods for marking artefactual components was performed. The performance of the methods was discussed in terms of their capability to 1) remove the artefact and 2) preserve the information of interest. The analysis included 12 subjects and two resting-state datasets for each of them. The results showed that none of the signal lengths for the ICA calculation was highly preferable to the other. Among the methods for the identification of PA-related components, the one based on the wavelets transform of each component emerged as the best compromise between the effectiveness in removing PA and the conservation of the physiological neuronal content.

Entropy analysis on EEG signal in a case study of focal myoclonus

Electrophysiological studies provide useful information for diagnosis and classification of myoclonus, and for the investigation of its generative mechanisms, due to association of myoclonus with abnormally increased excitability of cortical structures. In this work we analyzed the polygraphic data of a 7-year old girl affected by continuous partial epilepsy with focal myoclonus both related and not related with epileptiform discharges on EEG. We applied Sample Entropy (SampEn) and Lempel-Ziv complexity (LZ) methods to investigate the regularity and complexity content of EEG recordings and to find possible analogies in the behaviour of non-parametric complexity measures in epilepsy and in myoclonus. Our results show that these algorithms succeeded in finding a significant difference between the hypothesized focus on C3 electrode and the contralateral electrode C4, for EEG correlated myoclonus. A significant difference between the two contralateral electrodes (C3–C4) was also found for non EEG correlated myoclonus, but only by means of SampEn. This preliminary study confirmed the ability of entropic methods in discriminating myoclonic events. Indeed, near the myoclonic focus location both SampEn and LZ methods showed below average values.

Chief medical officer actions on information security in an Italian rehabilitation centre

In a multi-speciality rehabilitation centre, where child neuropsychiatrists, neurologists, physical rehabilitators, psychologists, nurses, therapists and other health care professionals actively care for patients, the moment will arrive when information security takes high priority on the chief medical officer (CMO) agenda. This has happened at the La Nostra Famiglia Institution. Local push to high priority arose from several concurrent forces, like privacy both on the patient and on the doctor side, legal and ethical aspects. Recommendations on the protection of medical data require appropriate technical and organisational measures to be taken to protect personal data against unauthorised access, alterations or any other form of inappropriate processing. In the same time quick and easy access to patient information should be granted to authorised personnel to ensure proper and in time treatment of patients. A long lasting sequence of co-operative negotiation meetings between the CMO and the chief information officer (CIO) led to appropriate outline of policies. We developed a suitable and modular architecture for designing systems that can simultaneously manage an increasing number of healthcare actors, objects and related access levels taking into account temporal conditions. Actions for keeping the prototype in use on an everyday basis are directly taken by the CMO.

Exploring the learnability and usability of a near field communication-based application for semantic enrichment in children with language disorders

ABSTRACT Recently, a few software applications (apps) have been developed to enhance vocabulary and conceptual networks to address the needs of children with language impairments (LI), but there is no evidence about their impact and their usability in therapy contexts. Here, we try to fill this gap presenting a system aimed at improving the semantic competence and the structural knowledge of children with LI. The goal of the study is to evaluate learnability, usability, user satisfaction and quality of the interaction between the system and the children. The system consists of a tablet, hosting an app with educational and training purposes, equipped with a Near Field Communication (NFC) reader, used to interact with the user by means of objects. Fourteen preschool children with LI played with the device during one 45-minute speech therapy session. Reactions and feedbacks were recorded and rated. The system proved to be easy to understand and learn, as well as engaging and rewarding. The success of the device probably rests on the integration of smart technology and real, tangible objects. The device can be seen as a valuable aid to support and enhance communication abilities in children with LI as well as typically developing individuals.