Amitabh Bhattacharya

University Health Network | UHN · Krembil Neuroscience Centre

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...

Background Spinocerebellar ataxia type 12 (SCA-12) is an uncommon autosomal dominant cerebellar ataxia characterized by action tremors in the upper limbs, dysarthria, head tremor, and gait ataxia. We aimed to evaluate the motor cortical excitability in patients with SCA-12 using transcranial magnetic stimulation (TMS). Methods The study was done in...

Over the past 30 years, the field of neuromodulation has witnessed remarkable advancements. These developments encompass a spectrum of techniques, both non-invasive and invasive, that possess the ability to both probe and influence the central nervous system. In many cases neuromodulation therapies have been adopted into standard care treatments. T...

Introduction: Vascular parkinsonism (VaP), type of lower body parkinsonism, occurs in relation to ischemic cerebrovascular disease. It can be associated with cognitive impairment. We aimed to study the cortical excitability changes in these patients using transcranial magnetic stimulation (TMS). Methods: We included 20 patients with VaP and 22 heal...

Introduction: Freezing of gait (FOG) is a clinical phenomenon with major life impairments and significant reduction in quality of life for affected patients. FOG is a feature of Parkinson’s Disease and a hallmark of primary progressive freezing of gait (PPGF), currently reclassified as Progressive Supranuclear Palsy-progressive gait freezing (PSP-P...

Objective We aimed to evaluate the effect of yoga on motor and non-motor symptoms and cortical excitability in patients with Parkinson’s disease (PD). Methods We prospectively evaluated 17 patients with PD at baseline, after one month of conventional care, and after one month of supervised yoga sessions. The motor and non-motor symptoms were evalu...

Background Early-onset Parkinson’s disease (EOPD) refers to patients with Parkinson’s disease (PD) whose age at disease onset is less than 50 years. Literature on the non-motor symptoms (NMS) in these patients is very limited in the Indian context. We aimed to study the NMS in patients with EOPD and its impact on the quality of life (QoL). Methods...

Background Dementia with Lewy body is a neurodegenerative disorder and is the second most common cause of dementia after Alzheimer’s disease. We aimed to study the demographic, clinical, neuropsychological, and imaging characteristics of these patients. Methods The current study is a retrospective chart review of 37 patients who met the diagnostic...

Background Vascular Parkinsonism (VP) is characterized by rigidity and bradykinesia predominantly affecting the lower limbs. Optical Coherence tomography (OCT) facilitates the visualization of retina and choroid and may help in delineating differential involvement of retina and choroid in patients with VP. In this study, we report the pattern of ch...

Eye Tracking is an important research technique used to analyze the movement of the eye and to recognize a pattern. Eye Tracking is a frequently used tool to understand the prognosis of a disease. iAOI is an Artificial Neural Network model that predicts the Area or Region of Interest viewed by a participant depending on the eye movement data. An ey...

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...

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...

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...

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...

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...