The dynamics of functional connectivity in patients with sensory neuronopathy: a Bayesian approach to characterize damaged neural circuitries

• Grant number: 16/00330-9
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: April 24, 2016
• End date: February 23, 2017
• Field of knowledge: Health Sciences - Medicine
• Principal Investigator: Marcondes Cavalcante Franca Junior
• Grantee: Raphael Fernandes Casseb
• Supervisor: Bradley Goodyear
• Host Institution: Faculdade de Ciências Médicas (FCM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: University of Calgary, Canada
• Associated to the scholarship: 14/15918-6 - Evaluation of motor activation pattern in patients with sensory neuronopathies using fMRI effective connectivity, BP.DD

Abstract

Sensory neuron diseases (SND) constitute a subgroup of peripheral nervous system diseases whose most striking feature is the primary degeneration of dorsal root ganglia. SND patients have sensory deficits in many parts of the body, which leads to impairment of motor coordination, although their primary motor brain areas remain intact. The effects of SND on the central nervous system have not yet been extensively evaluated. Imaging strategies employed until now only involved the use of structural magnetic resonance imaging (MRI) to describe volume changes in cerebral and non-cerebral structures (e.g., the atrophy of the cerebellum and of the dorsal root ganglia). Nevertheless, to the best of our knowledge, functional MRI has not yet been used to study functional connectivity (fc-fMRI) abnormalities associated with SN. It should be noted that damage from other neurological disorders, such as Parkinson's disease (PD), have already been characterized through the use of fc-fMRI. In this scenario we think that the study of SND may help elucidate mechanisms of sensory-motor integration, since SN is a purely sensory disorder with motor impairment, while PD, in contrast, is an exclusive motor disorder.One limitation of current fc-fMRI technique, however, is the assumption that functional connections are constant over time. New analysis strategies have been recently introduced, such as sliding window analysis, which analyze a small fragment (window) of signals, and then shifts the window over time. This permits an analysis of functional connectivity dynamics. As we postulate that SND affects BOLD signal time courses, it is reasonable to adopt such a strategy. Improvements of the sliding window technique were recently proposed by Dr. Bradley Goodyear at the university of Calgary and my goal will be to apply this enhanced version of the method in the fMRI data from a group of PD patients - that I will help to acquire, since fc-fMRI alterations are well described in this condition. Then, the same approach is going to be used in the analysis of SND fMRI data, and this may: (i) give us insights about disease mechanisms, (ii) provide parameters (biomarkers) to aid in diagnose and/or prognosis and (iii) reveal possible neural targets to be submitted to therapy using neuromodulation. (AU)