Advanced neuroimaging methodologies to improve connectivity detection in normal and abnormal language brain networks

The language connectome was in-vivo investigated using multimodal non-invasive quantitative MRI. In PPA patients (n=18) recruited by the IRCCS ISNB, Bologna, cortical thickness measures showed a predominant reduction on the left hemisphere (p<0.005) with respect to matched healthy controls (HC) (n=18), and an accuracy of 86.1% in discrimination from Alzheimer’s disease patients (n=18). The left temporal and para-hippocampal gyri significantly correlated (p<0.01) with language fluency. In PPA patients (n=31) recruited by the Northwestern University Chicago, DTI measures were longitudinally evaluated (2-years follow-up) under the supervision of Prof. M. Catani, King’s College London. Significant differences with matched HC (n=27) were found, tract-localized at baseline and widespread in the follow-up. Language assessment scores correlated with arcuate (AF) and uncinate (UF) fasciculi DTI measures. In left-ischemic stroke patients (n=16) recruited by the NatBrainLab, King’s College London, language recovery was longitudinally evaluated (6-months follow-up). Using arterial spin labelling imaging a significant correlation (p<0.01) between language recovery and cerebral blood flow asymmetry, was found in the middle cerebral artery perfusion, towards the right. In HC (n=29) recruited by the DIBINEM Functional MR Unit, University of Bologna, an along-tract algorithm was developed suitable for different tractography methods, using the Laplacian operator. A higher left superior temporal gyrus and precentral operculum AF connectivity was found (Talozzi L et al., 2018), and lateralized UF projections towards the left dorsal orbital cortex. In HC (n=50) recruited in the Human Connectome Project, a new tractography-driven approach was developed for left association fibres, using a principal component analysis. The first component discriminated cortical areas typically connected by the AF, suggesting a good discrimination of cortical areas sharing a similar connectivity pattern. The evaluation of morphological, microstructural and metabolic measures could be used as in-vivo biomarkers to monitor language impairment related to neurodegeneration or as surrogate of cognitive rehabilitation/interventional treatment efficacy.

Cognitive Assessment and Rehabilitation of subjects with Traumatic Brain Injury

This thesis regards the study and the development of new cognitive assessment and rehabilitation techniques of subjects with traumatic brain injury (TBI). In particular, this thesis i) provides an overview about the state of art of this new assessment and rehabilitation technologies, ii) suggests new methods for the assessment and rehabilitation and iii) contributes to the explanation of the neurophysiological mechanism that is involved in a rehabilitation treatment. Some chapters provide useful information to contextualize TBI and its outcome; they describe the methods used for its assessment/rehabilitation. The other chapters illustrate a series of experimental studies conducted in healthy subjects and TBI patients that suggest new approaches to assessment and rehabilitation. The new proposed approaches have in common the use of electroencefalografy (EEG). EEG was used in all the experimental studies with a different purpose, such as diagnostic tool, signal to command a BCI-system, outcome measure to evaluate the effects of a treatment, etc. The main achieved results are about: i) the study and the development of a system for the communication with patients with disorders of consciousness. It was possible to identify a paradigm of reliable activation during two imagery task using EEG signal or EEG and NIRS signal; ii) the study of the effects of a neuromodulation technique (tDCS) on EEG pattern. This topic is of great importance and interest. The emerged founding showed that the tDCS can manipulate the cortical network activity and through the research of optimal stimulation parameters, it is possible move the working point of a neural network and bring it in a condition of maximum learning. In this way could be possible improved the performance of a BCI system or to improve the efficacy of a rehabilitation treatment, like neurofeedback.

Psychosocial correlates of rehabilitation from stroke: a longitudinal study

The general aim of this dissertation was to uncover the association between psychosocial factors and rehabilitation outcome after stroke. METHOD. A sample of patients with stroke (n=40) and their caregivers (n=36) were assessed at admission to and six months after discharge from rehabilitation hospital, using the following instruments: Structured Clinical Interview for DSM-IV, structured interview based on Diagnostic Criteria for Psychosomatic Research, Symptom Questionnaire, Psychosocial Index, Psychological Well-Being Scales, and Family Assessment Device. 40 subjects from the general population underwent the same psychological assessment. In addition, patients' functional status was measured using the Functional Independence Measure. RESULTS. Stroke survivors reported lower education and higher alcohol consumption than controls. No significant differences emerged between the two groups in the prevalence of psychiatric diagnoses or psychosomatic syndromes, however patients reported significantly higher levels of anxiety, depression, somatic symptoms, and lower autonomy than controls. Caregivers reported significantly higher scores in anxiety, depression, and somatic symptoms compared to normative data, while no impairments emerged in psychological well-being and family functioning. At six-month follow-up, in patients a significant decrease in smoking habit and an increase in DSM diagnoses were reported. Both stroke survivors and caregivers showed significant reductions in anxiety, with patients displaying also a decrease in somatic symptoms, an increase in stress and a deterioration in quality of life. Significant deteriorations in several aspects of family functioning was perceived only by patients. An association between patients' functional recovery in the cognitive domain and family behavior control emerged. For caregivers, family functioning significantly predicted hostility and somatic symptoms were associated with family affective involvement. CONCLUSIONS. These data highlight the utility in the Italian setting of the adoption of a psychosocial assessment and a family-systems approach in stroke rehabilitation, in order to development interventions properly targeted to the characteristics of patients and their family members.