Amitabh Bhattacharya

University of Toronto | U of T · Toronto Western Research Institute - TWRI

The brain has the innate ability to undergo neuronal plasticity, which refers to changes in its structure and functions in response to continued changes in the environment. Although these concepts are well established in animal slice preparation models, their application to a large number of human subjects could only be achieved using noninvasive b...

Background: Rapid eye movement sleep behaviour disorder (RBD) is considered to be one of the most frequent and important prodromal symptoms of Parkinson’s disease (PD). We aimed to study the neurophysiological abnormalities in patients of PD-RBD and PD without RBD (PD-nRBD) using transcranial magnetic stimulation (TMS). Methods: Twenty patients ea...

Cognitive impairment of different severity with eventual progression to dementia in Parkinson’s disease (PD) appears during the course of the disease. In this study, transcranial magnetic stimulation (TMS) was used to assess cortical excitability changes in PD patients with varying cognitive impairment. We aimed to identify the TMS parameters that...

This chapter reviews the alterations in motor learning and motor cortical plasticity in Parkinson's disease (PD), the most common movement disorder. Impairments in motor learning, which is a hallmark of basal ganglia disorders, influence the performance of motor learning-related behavioral tasks and have clinical implications for the management of...

This review is part of the series on the clinical neurophysiology of movement disorders. It focuses on Parkinson’s disease and parkinsonism. The topics covered include the pathophysiology of tremor, rigidity and bradykinesia, balance and gait disturbance and myoclonus in Parkinson’s disease. The use of electroencephalography, electromyography, long...

INTRODUCTION: The coronavirus disease-19 (COVID-19) pandemic is a global health crisis that has directly and indirectly impacted almost all populations globally. In this study, we aimed to study the impact of the COVID-19 pandemic on motor and nonmotor symptoms in patients with various movement disorders who visited our outpatient department. MATER...

Background: Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism. We aimed to study the abnormalities in the retinal layers in patients with WD using optical coherence tomography (OCT). Methods: The study is a chart review of 16 patients with WD (six females) who underwent OCT at our hospital during follow-up visits. Spe...

Introduction: Vascular Parkinsonism (VaP) is characterized by symmetric, predominantly lower limb bradykinesia and rigidity and no significant improvement with levodopa. We aimed to describe the clinical and radiological features of patients with VaP and the factors that determine levodopa responsiveness. Methods: This is a retrospective chart r...

We review the findings for motor cortical excitability, plasticity and evoked potentials in dystonia. Plasticity can be induced and assessed in cortical areas by non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and the invasive technique of deep brain stimulation (DBS), which allows access to deep brain stru...

Introduction We aimed to study the cortical and intracortical functions in patients of ET using transcranial magnetic stimulation (TMS) and to evaluate the effect of continuous theta burst stimulation (cTBS) on the tremor characteristics. Methods Ten ET and 20 healthy controls were included in the study. All the participants were evaluated with TM...

Background: Establishing an association between gait variability and direction specific balance indices may help in identifying the risk of falls in patients with spinocerebellar ataxia (SCA) which may help in developing an appropriate intervention. This study is intended to identify the association between balance and gait parameters especially g...

Background: Parkinson’s disease (PD) is characterized by bradykinesia, tremor, rigidity, postural instability and cognitive deficits in attention, executive functions, learning and memory. Motor speed, measured using Finger Tapping Test (FTT), is an important indicator and predictor of cognitive and motor functions. Deficits in motor speed have sig...

INTRODUCTION: Numerous studies in Huntington’s disease (HD) have shown striatum as the major site of neuronal loss, but recently the presence of neurodegeneration in other regions of the brain is gaining attention. In our study, we used voxel-based morphometry and diffusion tensor imaging to identify other areas in the brain that are involved in th...

Despite anti-cholinergics being the oldest type of medication used for the treatment of Parkinson's disease (PD), the mechanism of action and exact benefit is unclear. This study compared the effectiveness of trihexyphenidyl (THP) and levodopa (LD) on motor symptoms in patients with PD. Patients with PD who are currently taking or had taken THP wer...

The practice of yoga is based on the traditional Indian philosophy. Children during their development show adaptive neuroplasticity which is due to long-term potentiation that causes changes in the synaptic transmission. Excessive plasticity in the developing brain can lead to maladaptive neuronal circuits which can cause hyperkinetic movement diso...

Introduction: Handwriting is a complex activity involving cognitive, kinaesthetic and perceptual-motor components playing a critical role in the context of assessing neurodegenerative disorders. Difficulties in handwriting can be related to the disease and its severity which can serve as a prominent biomarker. This study proposes a methodology to m...

Objectives: Functional movement disorders (FMD) pose significant diagnostic and management challenges. We aimed to study the socio-economic and cultural factors, underlying psychopathology and the phenomenology of FMDs in children. Materials and Methods: The study is a retrospective chart review of 39 children (16 girls and 23 boys) who attended o...

Objective: Willingness to undergo deep brain stimulation (DBS) among patients with Parkinson's disease (PD) and their overall satisfaction with the procedure is highly dependent upon expectations, which are based on the core concepts of knowledge, attitude and perceptions. The present study aims to evaluate these factors in patients and caregivers...

Background Idiopathic normal pressure hydrocephalus (iNPH) is characterized by the clinical triad of gait disturbance, urinary incontinence, and memory impairment with normal cerebrospinal fluid (CSF) pressure. Transcranial magnetic stimulation (TMS) has been used to assess the corticospinal motor pathways in patients with iNPH with conflicting res...

Sleep disturbance is one of the commonly reported non-motor symptoms in patients with Parkinson's disease (PD) as well as in Parkinson plus disorders such as multiple system atrophy (MSA), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP), and corticobasal syndrome (CBS). Although there is a wealth of literature on sleep disturb...

Introduction: Cognitive impairment in Parkinson’s disease (PD) usually develops years after the onset of motor symptoms and leads to significant disability. Our aim was to determine the pattern of cortical excitability, inhibitory and facilitatory profile in patients with PD, PD with mild cognitive impairment (MCI) and PD with dementia (PDD) using...

Background: • Gait abnormality, urinary disturbances and cognitive impairment form the triad of normal pressure hydrocephalus • Transcranial Magnetic Stimulation (TMS) is a novel technique to study the corticospinal excitability and integrity of connections between cortical and subcortical structures. Objectives: • To study the cortical excitabilit...

Objective: To evaluate the motor cortical excitability changes in PD patients with and without RBD. Background: There has been an increase in the understanding of the pathophysiology of REM sleep behaviour disorder (RBD) in patients with Parkinson’s disease (PD) due to recent advances in the neurophysiological techniques. Studies of the motor cort...

Academic performance has been found to be a significant source of stress among children and adolescents. Understanding the behavioural and electrophysiological correlates of academic stress implies the need for stress management programs in schools. The present study was conducted to compare the behavioural and electrophysiological outcome of the s...

Tobacco smoking is one of the biggest public health threats worldwide. To control and prevent this threat countrywide the Indian Government has initiated anti-smoking mass media campaigning by broadcasting these advertisements during movies and serials. The present study was conducted to analyze the behavioural and electrophysiological correlates o...