Biography
Peter Riley is a Consultant Medical Physicist employed as a Senior Lecturer for Diagnostic Imaging & Medical Physics, with the School of Medicine at Deakin University, Waurn Ponds. His publications include mathematical modeling of tumour growth and the application of neural networks for computer aided diagnosis in nuclear medicine imaging.
Abstract
There are numerous diseases of the nervous system which manifest abnormal sleep-wake cycles and there are many explanatory mechanisms identifying various neurochemical species involvements1. The Hobson AIM model2 of brain activation provides a state-space model which includes sleep-wake states, but which does not readily explain the sometimes abrupt transitions between states observed clinically. The presence of abrupt state changes suggests an underlying non-linear mechanism characteristic of a cusp catastrophe. A simple model is proposed which originates from logistic growth of competing neurotransmitters promoting and demoting neural activation with the addition of a scavenging mechanism modeled as a sigmoid process. The model shows potential state trajectories which include: 1. Smoothe transitions from sleep-wake states as a “normal†process. 2. Catastrophic transitions from the wake state to the sleep state, reminiscent of narcolepsy. 3. Catastrophic transitions from the sleep state to the wake state. 4. Rapid cycling between sleep and wake states, reminiscent of delirium. 5. An intermediate bifurcation point which may correspond to the normal NREM state.
Biography
Dr Tommasin completed her PhD studies at the Physics department of Sapienza University of Rome in 2010 and since then has worked as postodoctoral fellow in Italy and Israel focusing on topic of neuroscientific and astronomical interest. Her main abilities include analysis of data, signals and images, and estimation of semi-analytical models. At the moment she works with the neuroradiology group of Sapienza University and investigates the role of neuroplasticity in disability progression of neurodegenerative disorders, such as multiple sclerosis
Abstract
The severity of disability and disease burden in Multiple Sclerosis (MS) patients may not coincide. In patients with no-to-moderate disability an increment in the recruitment of crucial cortical areas has been hypothesized to attenuate the negative effects of structural damage accumulation. Functional connectivity (FC) changes may be associated with relatively preserved neurological functions in the early phases of the disease. We studied FC in 119 patients (28 males, age 39.9±10.1) with diagnosed MS at different stages; no treatments or medication change in the three months prior to enrollment; no uncertain diagnosis, concomitant relevant diseases or contraindications to magnetic resonance imaging (MRI). Patients underwent a neurological evaluation (median Expanded Disability Status Scale, EDSS, 2) and MRI. 41 age- and gender-matched healthy subjects with no previous history of neurological diseases were enrolled as control group. Functional MRI was acquired at 3.0T and included single-shot echo-planar resting state (140TR, TR=3seconds), high resolution 3D-T1-weighted and dual-echo T2-weighted images. Images were processed through FSL and homemade MATLAB tools. We found that FC changes strongly depend on brain topology, being disability and FC positively correlated in frontal regions and negatively correlated across cerebellar and temporal/frontal regions. The model that better predicts the FC-EDSS relation between frontal regions increases linearly, as example of maladaptive plasticity. Conversely, FC of the cerebellum with temporal and frontal regions shows an initial upraise, as possible compensatory adaptive plasticity, and could be addressed as therapeutic targets.