Mark Hallett

Bio: Mark Hallett is an academic researcher from National Institutes of Health. The author has contributed to research in topics: Transcranial magnetic stimulation & Motor cortex. The author has an hindex of 186, co-authored 1170 publications receiving 123741 citations. Previous affiliations of Mark Hallett include Government of the United States of America & Armed Forces Institute of Pathology.

Progressive supranuclear palsy (PSP): Richardson syndrome and other PSP variants

Abstract: Phenotypic heterogeneity of progressive supranuclear palsy (PSP) has been increasingly reported in the literature and can be the source of incorrect clinical diagnosis particularly in the early stages of the disease when the classically associated symptoms of early falls and supranuclear gaze palsy may not be apparent. In addition to Richardson syndrome (RS), several atypical clinical phenotypes have been described. Advances in genetic, neuroimaging, and biochemical/molecular technologies contribute to the identification of these clinical subtypes in the context of typical PSP pathological findings. Our goal is to review the phenomenology reported in the literature that is associated with confirmed histopathological changes consistent with a PSP diagnosis and to highlight the clinical spectrum of PSP. A systematic review of the literature in PubMed through July 2015 using MeSH terms and key words related to PSP was conducted. Articles describing PSP classifications, diagnostic criteria, and case reports were reviewed and summarized. Additional PSP phenotypes not seen in recent clinicopathological studies are included. These include primary lateral sclerosis, pallido-nigro-luysian degeneration, axonal dystrophy, and multiple system atrophy in the spectrum of atypical PSP variants beyond the traditionally classified PSP subtypes. This review is intended to help with the diagnostic challenges of atypical PSP variants. We believe that large multicenter clinicopathological studies will help expand our understanding of etiology and specific mechanisms of neurodegeneration and will aid in the appropriate interpretation of outcomes when conducting clinical and basic science research.

Chronic low-frequency rTMS of primary motor cortex diminishes exercise training-induced gains in maximal voluntary force in humans

Abstract: Although there is consensus that the central nervous system mediates the increases in maximal voluntary force (maximal voluntary contraction, MVC) produced by resistance exercise, the involvement o...

Psychiatric symptoms associated with focal hand dystonia

Abstract: Myoclonus dystonia and idiopathic dystonia are associated with a greater frequency of obsessive compulsive disorder (OCD) and major depression. We investigated the frequency of OCD in 39 patients with primary focal hand dystonia (FHD) using a semistructured interview. OCD and subsyndromal OCD was diagnosed in 5 of 39 (12.82%) patients with FHD, whereas OCD occurs in 2.3% of the general population. Recurrent depression occurred in (7 of 39) 17.95% of patients with FHD along with a family history of depression in (16 of 39) 41.02%. Overlapping mechanisms manifesting as FHD may also predispose to OC symptoms and likely implicates a common striatal dysfunction.

The Bereitschaftspotential: What Does It Measure and where Does It Come from?

Abstract: The Bereitschaftspotential (BP) is a negative cortical potential which develops beginning 1. 5 to 1 s prior to the onset of a self-paced movement (see Figure 1). The BP was first described by Kornhuber & Deecke in 1964, which makes it about 38 years old. Before the days that citation indices and impact factors came into vogue, one criterion for the significance of a research finding or paper was whether it led to other research studies. By this criterion, the BP has been incredibly influential. The BP has become a well-established tool in the motor physiology laboratory (Marsden et al, 1986), and from recent publications in scientific journals it is evident that the BP is also very much alive and well as a research tool. Its amplitude, slope, and/or latency have been shown to be impaired in neurological disorders such as Parkinson’s disease (Dick et al, 1989; Jahanshahi et al, 1995; Cunnington et al, 1995; Praamstra et al, 1996a), Huntington’s disease (Johnson et al, 2001), dystonia (Van der Kemp et al, 1995; Deuschl et al, 1995), cerebellar disease (Shibasaki et al, 1978; Verleger et al, 1999; Wessel et al, 1994), and psychiatric disorders such as schizophrenia (eg Singh et al, 1992; Fuller et al, 1999; Northoff et al, 2000) and depression (Khanna et al, 1989; Haag et al, 1994) and in patients with focal lesions of the thalamus (Shibasaki, 1975; Green et al, 1999; Feve et al, 1996), basal ganglia (Feve et al, 1994; Kitamura et al, 1996) cerebellum (Shibasaki et al, 1978; Ikeda et al, 1994; Gerloff et al, 1996), prefrontal (Shibasaki, 1975; Singh & Knight, 1990; Honda et al, 1997) or parietal (Knight et al, 1989; Singh & Knight, 1993) cortices. In the last decade, there has been a surge of interest in the BP with the demonstration that besides simple movement Parameters such as force (Kutas & Donchin, 1980) and rate (Mackinnon et al, 1996) higher order motor processes such as movement complexity (Benecke et al, 1985; Simonetta et al, 1991) and mode of movement selection (Jahanshahi et al, 1995; Touge et al, 1995; Praamstra et al, 1996a; Dirnberger et al, 1998) affect its amplitude or slope.

Novel PRNP sequence variant associated with familial encephalopathy.

Abstract: Human transmissible spongiform encephalopathies (TSEs) are a group of chronic progressive neurodegenerative disorders that may be hereditary, infectious, or sporadic. Hereditary TSEs are associated with mutations in the PRNP gene on chromosome 20p12-pter. We report on a family in which seven patients developed limb and truncal ataxia, dysarthria, myoclonic jerks, and cognitive decline. The age of onset in the 30s, 40s, or 50s, prolonged disease duration, cerebellar atrophy on imaging, and the presence of synchronic periodic discharges on electroencephalogram suggested a familial encephalopathy resembling Gerstmann-Straussler-Scheinker disease. A novel H187R mutation has been identified in affected, but not in unaffected, family members or unrelated controls suggesting a pathogenic role for this mutation. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:653-656, 1999. Published 1999 Wiley-Liss, Inc.

The Brain's Default Network Anatomy, Function, and Relevance to Disease

Abstract: Thirty years of brain imaging research has converged to define the brain’s default network—a novel and only recently appreciated brain system that participates in internal modes of cognition Here we synthesize past observations to provide strong evidence that the default network is a specific, anatomically defined brain system preferentially active when individuals are not focused on the external environment Analysis of connectional anatomy in the monkey supports the presence of an interconnected brain system Providing insight into function, the default network is active when individuals are engaged in internally focused tasks including autobiographical memory retrieval, envisioning the future, and conceiving the perspectives of others Probing the functional anatomy of the network in detail reveals that it is best understood as multiple interacting subsystems The medial temporal lobe subsystem provides information from prior experiences in the form of memories and associations that are the building blocks of mental simulation The medial prefrontal subsystem facilitates the flexible use of this information during the construction of self-relevant mental simulations These two subsystems converge on important nodes of integration including the posterior cingulate cortex The implications of these functional and anatomical observations are discussed in relation to possible adaptive roles of the default network for using past experiences to plan for the future, navigate social interactions, and maximize the utility of moments when we are not otherwise engaged by the external world We conclude by discussing the relevance of the default network for understanding mental disorders including autism, schizophrenia, and Alzheimer’s disease

Parallel Organization of Functionally Segregated Circuits Linking Basal Ganglia and Cortex

Abstract: Information about the basal ganglia has accumulated at a prodigious pace over the past decade, necessitating major revisions in our concepts of the structural and functional organization of these nuclei. From earlier data it had appeared that the basal ganglia served primarily to integrate diverse inputs from the entire cerebral cortex and to "funnel" these influences, via the ventrolateral thalamus, to the motor cortex (Allen & Tsukahara 1974, Evarts & Thach 1969, Kemp & Powell 1971). In particular, the basal

FieldTrip: open source software for advanced analysis of MEG, EEG, and invasive electrophysiological data

Abstract: This paper describes FieldTrip, an open source software package that we developed for the analysis of MEG, EEG, and other electrophysiological data. The software is implemented as a MATLAB toolbox and includes a complete set of consistent and user-friendly high-level functions that allow experimental neuroscientists to analyze experimental data. It includes algorithms for simple and advanced analysis, such as time-frequency analysis using multitapers, source reconstruction using dipoles, distributed sources and beamformers, connectivity analysis, and nonparametric statistical permutation tests at the channel and source level. The implementation as toolbox allows the user to perform elaborate and structured analyses of large data sets using the MATLAB command line and batch scripting. Furthermore, users and developers can easily extend the functionality and implement new algorithms. The modular design facilitates the reuse in other software packages.

Principles of Neural Science

Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or