The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Jeremy D Schmahmann - One of the best experts on this subject based on the ideXlab platform.
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The Role of the Cerebellum in Cognition and Emotion
2020Co-Authors: Jeremy D SchmahmannAbstract:The traditional notion regarding cerebellar function has been that it is important for coordinating voluntary motor activity (1). Early studies of patients with degenerative cerebellar diseases or focal cerebellar injuries (2) described ataxia (wide-based lurching gait) and Dysmetria (inaccuracy and wavering unsteadiness or dysrhythmia of directed extremity movements). These observations led to the conclusion that when cerebellum malfunctions, balance and coordination are impaired, tremor is evident, eye movements are disordered, speech is dysarthric, and handwriting is illegible. Theories of cerebellar function, experiments to test the role of the cerebellum in nervous system, and the interpretation of previously available cerebellar anatomy have been predicated on the hypothesis that cerebellum is a motor control device.
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The Theory and Neuroscience of Cerebellar Cognition.
Annual Review of Neuroscience, 2019Co-Authors: Jeremy D Schmahmann, Xavier Guell, Catherine J. Stoodley, Mark A. HalkoAbstract:Cerebellar neuroscience has undergone a paradigm shift. The theories of the universal cerebellar transform and Dysmetria of thought and the principles of organization of cerebral cortical connectio...
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embodied cognition and the cerebellum perspectives from the Dysmetria of thought and the universal cerebellar transform theories
Cortex, 2017Co-Authors: John D E Gabrieli, Xavier Guell, Jeremy D SchmahmannAbstract:Abstract In this report, we analyze the relationship between embodied cognition and current theories of the cerebellum, particularly the Dysmetria of Thought theory and the concept of the Universal Cerebellar Transform (UCT). First, we describe the UCT and the Dysmetria of Thought theories, highlight evidence supporting these hypotheses and discuss their mechanisms, functions and relevance. We then propose the following relationships. (i) The UCT strengthens embodied cognition because it provides an example of embodiment where the nature and intensity of the dependence between cognitive, affective and sensorimotor processes are defined. (ii) Conversely, embodied cognition bolsters the UCT theory because it contextualizes a cerebellum-focused theory within a general neurological theory. (iii) Embodied cognition supports the extension to other brain regions of the principles of organization of cerebral cortical connections that underlie the UCT: The notion that cytoarchitectonically determined transforms manifest via connectivity as sensorimotor, cognitive and affective functions resonates with the embodiment thesis that cognitive, affective and sensorimotor systems are interdependent. (iv) Embodied cognition might shape future definitions of the UCT because embodiment redefines the relationship between the neurological systems modulated by the UCT. We conclude by analyzing the relationship between our hypotheses and the concept of syntax and action semantics deficits in motor diseases.
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Dysmetria of thought and the universal cerebellar transform empirical evidence future approaches and relevance for embodied cognition s18 007
Neurology, 2017Co-Authors: Xavier Guell, Catherine J. Stoodley, Mark A. Halko, Faranak Farzan, Alvaro Pascualleone, John D E Gabrieli, Jeremy D SchmahmannAbstract:Objective: To describe the Dysmetria of Thought Theory and its embedded notion of the Universal Cerebellar transform (UCT; Schmahmann, 1991, 2000), summarize tests of the theory, contextualize the theory within conceptions of embodied cognition, and outline future experimental approaches to test these hypotheses. Background: Anatomical, clinical, structural, and functional neuroimaging studies established a cerebellar role in cognition and emotion in addition to motor control. The existence of a UCT is a fundamental underpinning of the Dysmetria of Thought theory, predicated on the uniformity of cerebellar cytoarchitecture, and supported by recent clinical and experimental observations. Design/Methods: Present a synopsis of recent studies from our group; consider the Dysmetria of Thought theory in relation to notions of embodied cognition; and describe planned neuroimaging approaches to test these hypotheses. Results: Three studies directly tested the UCT. i) Cerebellar transcranial magnetic stimulation (TMS) with resting state functional connectivity MRI revealed topographically precise cerebrocerebellar interactions (Halko 2014), ii) Cerebellar TMS showed that specific cerebellar subregions control the temporal dynamics of the electrophysiological networks they are engaged in (Farzan 2015), iii) cerebellar patients have metalinguistic deficits that disrupt cognitive processes necessary for sentence production, sentence interpretation, and analysis and sequential logical reasoning (Guell 2015). These studies complement those showing topography of function within human cerebellum in fMRI and lesion-deficit studies (Stoodley 2012, 2016). The findings point to a uniform pattern of cerebellar modulation (the UCT), and invite a consideration of the Dysmetria of Thought theory within the context of the notion of embodied cognition. Conclusions: The Dysmetria of Thought theory with its notion of a UCT has ushered in a new understanding of cerebellar function and the cerebellar role in motor control, cognition and neuropsychiatry. Future imaging studies of movement, cognition and emotion are planned in cerebellar patients, Parkinson’s disease and healthy controls to further test these theories with empirical evidence. Study Supported by: Supported in part by the NIMH R01MH67980, NIMH R01MH111868, NIMH Sidney R. Baer, Jr. Foundation, La Caixa Banking Foundation, National Ataxia Foundation, and MINDlink Foundation. Disclosure: Dr. Guell has nothing to disclose. Dr. Halko has nothing to disclose. Dr. Farzan has nothing to disclose. Dr. Stoodley has nothing to disclose. Dr. Pascual-Leone has received personal compensation for activities with Magstim, Nexstim, Neuronix, Starlab Neuroscience, Neuroelectrics, Axilum Robotics, and Neosync as a member of scientific advisory boards. Dr. Pascual-Leone has received personal compensation in an editorial capacity for the Annals of Neurology and the European Journal of Neuroscience. Dr. Gabrieli has nothing to disclose. Dr. Schmahmann has received personal compensation for activities with Ataxion, Biohaven, Biogen, Pfizer, Takeda as a consultant. Dr. Schmahmann has received royalty payments from Elsevier, Oxford, MacKeith, and Springer. Dr. Schmahmann has received license fees payments from Massachusetts General Hospital.
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Ataxia after pontine stroke: Insights from pontocerebellar fibers in monkey
Annals of Neurology, 2004Co-Authors: Jeremy D Schmahmann, Douglas L. Rosene, Deepak N. PandyaAbstract:Basis pontis lacunes cause contralateral but rarely ipsilateral ataxia. We explored this phenomenon with isotope tract tracing in the rhesus monkey. Labeled pontocerebellar fibers cross midline and disperse widely in the opposite hemipons before coalescing in the brachium pontis. This anatomical arrangement suggests that small pontine strokes spare sufficient decussating pontocerebellar fibers to prevent ipsilateral Dysmetria, and that ipsilateral Dysmetria after large pontine stroke represents a disconnection syndrome.
Evangelos A Christou - One of the best experts on this subject based on the ideXlab platform.
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Quantitative Separation of Tremor and Ataxia in Essential Tremor
Annals of Neurology, 2020Co-Authors: Agostina Casamento-moran, David E Vaillancourt, Basma El Yacoubi, Bradley J. Wilkes, Christopher W. Hess, Kelly D. Foote, Michael S. Okun, Aparna Wagle Shukla, Evangelos A ChristouAbstract:OBJECTIVE: This study addresses a very important problem in Neurology, distinguishing tremor and ataxia using quantitative methods. Specifically, we aimed to quantitatively separate Dysmetria, a cardinal sign of ataxia, from tremor in Essential Tremor (ET). METHODS: In experiment 1, we compared nineteen participants diagnosed with ET undergoing thalamic deep brain stimulation (DBS; ETDBS ) to 19 healthy controls (HC). We quantified tremor during postural tasks using accelerometry and Dysmetria with fast, reverse-at-target goal-directed movements. To ensure that endpoint accuracy was unaffected by tremor, we quantified Dysmetria in selected trials manifesting a smooth trajectory to the endpoint. Finally, we manipulated tremor amplitude by switching DBS ON and OFF to examine its effect on Dysmetria. In experiment 2, we compared 10 ET participants (ET) with 10 HC to determine if we could identify and distinguish Dysmetria from tremor in non-DBS ET. RESULTS: Three findings suggest that we can quantify Dysmetria independent of tremor in ET. First, ETDBS and ET exhibited greater Dysmetria than HC and Dysmetria did not correlate with tremor (R2 0.2). INTERPRETATION: We demonstrate that Dysmetria can be quantified independent of tremor using fast, reverse at target goal-directed movements. These results have important implications for the understanding of ET and other cerebellar and tremor disorders. Future research should examine the neurophysiological mechanisms underlying each symptom and characterize their independent contribution to disability. This article is protected by copyright. All rights reserved.
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temporal but not spatial Dysmetria relates to disease severity in fa
Journal of Neurophysiology, 2020Co-Authors: Manuela Corti, Agostina Casamentomoran, Stefan Delmas, Samantha Bracksieck, Jessica Bowman, Blake Meyer, Samantha Norman, S Subramony, Evangelos A ChristouAbstract:For the first time, we quantified spatial and temporal Dysmetria and its relation to disease severity in Friedreich’s ataxia (FA). We found that FA individuals exhibit temporal but not spatial dysm...
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Dysmetria in myotonic dystrophy type 1 p5 441
Neurology, 2018Co-Authors: S Subramony, Agostina Casamentomoran, Basma El Yacoubi, Donovan J Lott, Evangelos A ChristouAbstract:Objective: To characterize voluntary movements in patients with myotonic dystrophy type 1 (DM1) Background: DM 1 is the most common muscular dystrophy inherited in autosomal dominant fashion. Motor impairments in DM1 are usually related to the muscle disease; but DM 1 clearly affects the central nervous system. Animal models suggest possible central contribution to motor deficits and possible cerebellar dysfunction. The purpose of this study was to characterize voluntary movements and their relation to central and peripheral impairments in DM1. Design/Methods: Ten individuals diagnosed with DM1 (38.8 ± 12.4 years, 4 women) and 10 age-matched controls (37.6 ± 16.9 years, 4 women) performed 50 trials of fast goal directed movements with ankle dorsiflexion aiming at a spatiotemporal target (9° at 180 ms). We recorded the mechanical and electromyographic activity of the primary agonist (tibialis anterior; TA) and antagonist (soleus; SOL) muscles and quantified the following: 1) Dysmetria: endpoint error in ankle dorsiflexion; 2) central impairments: movement variability and the modulation of the agonist muscle activity in the first 100 ms of the contraction; 3) peripheral impairments: time for muscle relaxation and muscle MRI. Results: Ankle Dysmetria was greater in DM1 patients than healthy controls (28.7 ± 10.4 vs 10.6 ± 2.5 %; P 2 =0.8, P 2 =0.15, P 2 =0.01, P>0.4) or tibialis anterior muscle T2 weight (R 2 =0.001, P>0.4). Conclusions: These findings provide novel evidence that DM1 patients exhibit Dysmetria relative to healthy controls and that central but not peripheral impairments contribute to these impairments. Study Supported by: DM-Wyck Foundation Disclosure: Dr. Subramony has nothing to disclose. Dr. Yacoubi has nothing to disclose. Dr. Casamento-Moran has nothing to disclose. Dr. Lott has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with PTC Therapeutics. Dr. Christou has nothing to disclose.
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force Dysmetria in spinocerebellar ataxia 6 correlates with functional capacity
Frontiers in Human Neuroscience, 2015Co-Authors: Agostina Casamentomoran, Yenting Chen, Minhyuk Kwon, Amy Snyder, S H Subramony, David E Vaillancourt, Evangelos A ChristouAbstract:Spinocerebellar ataxia type 6 (SCA6) is a genetic disease that causes pure cerebellar degeneration affecting walking, balance, and coordination. One of the main symptoms of SCA6 is Dysmetria. The magnitude of Dysmetria and its relation to functional capacity in SCA6 has not been studied. Our purpose was to quantify Dysmetria and determine the relation between Dysmetria and functional capacity in SCA6. Ten individuals diagnosed and genetically confirmed with SCA6 (63.7 ± 7.02yrs) and nine age-matched healthy controls (65.9 ± 8.5yrs) performed goal-directed isometric contractions with the ankle joint. Dysmetria was quantified as the force and time error during goal-directed contractions. SCA6 functional capacity was determined by ICARS and SARA clinical assessments. We found that SCA6 participants exhibited greater force Dysmetria than healthy controls (P < 0.05), and reduced time Dysmetria than healthy controls (P < 0.05). Only force Dysmetria was significantly related to SCA6 functional capacity, as measured with ICARS kinetic score (R2 = 0.63), ICARS total score (R2 = 0.43), and SARA total score (R2 = 0.46). Our findings demonstrate that SCA6 exhibit force Dysmetria and that force Dysmetria is associated to SCA6 functional capacity. Quantifying force and time Dysmetria in individuals with SCA6 could provide a more objective evaluation of the functional capacity and disease state in SCA6.
Heinrich Sauer - One of the best experts on this subject based on the ideXlab platform.
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supporting evidence for the model of cognitive Dysmetria in schizophrenia a structural magnetic resonance imaging study using deformation based morphometry
Schizophrenia Research, 2000Co-Authors: Hanspeter Volz, Christian Gaser, Heinrich SauerAbstract:Abstract The aim of the study was to investigate whether there is any structural evidence for the model of ‘cognitive Dysmetria’ in schizophrenia if an automatic whole-brain analysis method is used. High-resolution magnetic resonance scans were obtained for 75 schizophrenic patients and 75 controls. These data were analysed using the recently developed deformation-based morphometry allowing the assessment of volumetric differences without a priori definition of regions of interest. When compared with controls, we found reduced volumes in patients with schizophrenia in the frontal lobe (gyrus frontalis superior, medius and medialis), the temporal lobe (gyrus temporalis superior and inferior), the thalamus, the left cerebellar hemisphere and the right cerebellar vermis. There was an increase in volume in the right putamen. To date, this is the first structural magnetic resonance imaging study to demonstrate that the three key-elements of the model of cognitive Dysmetria — frontal lobe, thalamus, and cerebellum — are reduced in volume in schizophrenic patients. This highlights the importance of this concept for future investigations.
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Supporting evidence for the model of cognitive Dysmetria in schizophrenia — a structural magnetic resonance imaging study using deformation-based morphometry
Schizophrenia Research, 2000Co-Authors: Hanspeter Volz, Christian Gaser, Heinrich SauerAbstract:Abstract The aim of the study was to investigate whether there is any structural evidence for the model of ‘cognitive Dysmetria’ in schizophrenia if an automatic whole-brain analysis method is used. High-resolution magnetic resonance scans were obtained for 75 schizophrenic patients and 75 controls. These data were analysed using the recently developed deformation-based morphometry allowing the assessment of volumetric differences without a priori definition of regions of interest. When compared with controls, we found reduced volumes in patients with schizophrenia in the frontal lobe (gyrus frontalis superior, medius and medialis), the temporal lobe (gyrus temporalis superior and inferior), the thalamus, the left cerebellar hemisphere and the right cerebellar vermis. There was an increase in volume in the right putamen. To date, this is the first structural magnetic resonance imaging study to demonstrate that the three key-elements of the model of cognitive Dysmetria — frontal lobe, thalamus, and cerebellum — are reduced in volume in schizophrenic patients. This highlights the importance of this concept for future investigations.
Xavier Guell - One of the best experts on this subject based on the ideXlab platform.
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The Theory and Neuroscience of Cerebellar Cognition.
Annual Review of Neuroscience, 2019Co-Authors: Jeremy D Schmahmann, Xavier Guell, Catherine J. Stoodley, Mark A. HalkoAbstract:Cerebellar neuroscience has undergone a paradigm shift. The theories of the universal cerebellar transform and Dysmetria of thought and the principles of organization of cerebral cortical connectio...
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embodied cognition and the cerebellum perspectives from the Dysmetria of thought and the universal cerebellar transform theories
Cortex, 2017Co-Authors: John D E Gabrieli, Xavier Guell, Jeremy D SchmahmannAbstract:Abstract In this report, we analyze the relationship between embodied cognition and current theories of the cerebellum, particularly the Dysmetria of Thought theory and the concept of the Universal Cerebellar Transform (UCT). First, we describe the UCT and the Dysmetria of Thought theories, highlight evidence supporting these hypotheses and discuss their mechanisms, functions and relevance. We then propose the following relationships. (i) The UCT strengthens embodied cognition because it provides an example of embodiment where the nature and intensity of the dependence between cognitive, affective and sensorimotor processes are defined. (ii) Conversely, embodied cognition bolsters the UCT theory because it contextualizes a cerebellum-focused theory within a general neurological theory. (iii) Embodied cognition supports the extension to other brain regions of the principles of organization of cerebral cortical connections that underlie the UCT: The notion that cytoarchitectonically determined transforms manifest via connectivity as sensorimotor, cognitive and affective functions resonates with the embodiment thesis that cognitive, affective and sensorimotor systems are interdependent. (iv) Embodied cognition might shape future definitions of the UCT because embodiment redefines the relationship between the neurological systems modulated by the UCT. We conclude by analyzing the relationship between our hypotheses and the concept of syntax and action semantics deficits in motor diseases.
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Dysmetria of thought and the universal cerebellar transform empirical evidence future approaches and relevance for embodied cognition s18 007
Neurology, 2017Co-Authors: Xavier Guell, Catherine J. Stoodley, Mark A. Halko, Faranak Farzan, Alvaro Pascualleone, John D E Gabrieli, Jeremy D SchmahmannAbstract:Objective: To describe the Dysmetria of Thought Theory and its embedded notion of the Universal Cerebellar transform (UCT; Schmahmann, 1991, 2000), summarize tests of the theory, contextualize the theory within conceptions of embodied cognition, and outline future experimental approaches to test these hypotheses. Background: Anatomical, clinical, structural, and functional neuroimaging studies established a cerebellar role in cognition and emotion in addition to motor control. The existence of a UCT is a fundamental underpinning of the Dysmetria of Thought theory, predicated on the uniformity of cerebellar cytoarchitecture, and supported by recent clinical and experimental observations. Design/Methods: Present a synopsis of recent studies from our group; consider the Dysmetria of Thought theory in relation to notions of embodied cognition; and describe planned neuroimaging approaches to test these hypotheses. Results: Three studies directly tested the UCT. i) Cerebellar transcranial magnetic stimulation (TMS) with resting state functional connectivity MRI revealed topographically precise cerebrocerebellar interactions (Halko 2014), ii) Cerebellar TMS showed that specific cerebellar subregions control the temporal dynamics of the electrophysiological networks they are engaged in (Farzan 2015), iii) cerebellar patients have metalinguistic deficits that disrupt cognitive processes necessary for sentence production, sentence interpretation, and analysis and sequential logical reasoning (Guell 2015). These studies complement those showing topography of function within human cerebellum in fMRI and lesion-deficit studies (Stoodley 2012, 2016). The findings point to a uniform pattern of cerebellar modulation (the UCT), and invite a consideration of the Dysmetria of Thought theory within the context of the notion of embodied cognition. Conclusions: The Dysmetria of Thought theory with its notion of a UCT has ushered in a new understanding of cerebellar function and the cerebellar role in motor control, cognition and neuropsychiatry. Future imaging studies of movement, cognition and emotion are planned in cerebellar patients, Parkinson’s disease and healthy controls to further test these theories with empirical evidence. Study Supported by: Supported in part by the NIMH R01MH67980, NIMH R01MH111868, NIMH Sidney R. Baer, Jr. Foundation, La Caixa Banking Foundation, National Ataxia Foundation, and MINDlink Foundation. Disclosure: Dr. Guell has nothing to disclose. Dr. Halko has nothing to disclose. Dr. Farzan has nothing to disclose. Dr. Stoodley has nothing to disclose. Dr. Pascual-Leone has received personal compensation for activities with Magstim, Nexstim, Neuronix, Starlab Neuroscience, Neuroelectrics, Axilum Robotics, and Neosync as a member of scientific advisory boards. Dr. Pascual-Leone has received personal compensation in an editorial capacity for the Annals of Neurology and the European Journal of Neuroscience. Dr. Gabrieli has nothing to disclose. Dr. Schmahmann has received personal compensation for activities with Ataxion, Biohaven, Biogen, Pfizer, Takeda as a consultant. Dr. Schmahmann has received royalty payments from Elsevier, Oxford, MacKeith, and Springer. Dr. Schmahmann has received license fees payments from Massachusetts General Hospital.
Nancy C Andreasen - One of the best experts on this subject based on the ideXlab platform.
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an mri study of cerebellar vermis morphology in patients with schizophrenia evidence in support of the cognitive Dysmetria concept
Biological Psychiatry, 1999Co-Authors: Peg Nopoulos, John W Ceilley, Elizabeth A Gailis, Nancy C AndreasenAbstract:Abstract Background: Cumulative evidence suggests the cerebellum is involved in cognition and may be important in the pathoetiology of schizophrenia. Functional imaging studies have identified a possible neural circuit that includes the cerebellum and may be abnormal in patients with schizophrenia, manifesting as a fundamental cognitive deficit conceptualized as cognitive Dysmetria. To explore the role of the cerebellum in cognitive dysfunction and schizophrenia, this study was designed to evaluate the morphology of the cerebellar vermis, its relationship to other cortical areas, and to cognitive function in patients with schizophrenia. Methods: Male patients with schizophrenia ( n = 65) were matched by age and gender to 65 healthy male controls. Volume measures of the 4 cerebral lobes and total cerebellum were obtained using automated methods. The area of the cerebellar vermis (divided into three lobes) was traced on a midsaggital MRI slice. Results: Patients had smaller frontal and temporal lobes. There were no group differences in total cerebellar volume. Patients had a smaller vermis area, accounted for by a smaller anterior lobe. The anterior vermis area was positively correlated with total cerebellar volume, temporal lobe volume, and FSIQ in patients, but not controls. Conclusions: These findings support the theory that regions of the cerebellum may be involved in a neural circuit that is structurally and functionally abnormal in patients with schizophrenia, leading to cognitive Dysmetria.
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dysfunctional cortico cerebellar circuits cause cognitive Dysmetria in schizophrenia
Neuroreport, 1998Co-Authors: A K Wiser, Nancy C Andreasen, Daniel S Oleary, G L Watkins, L Boles L Ponto, Richard D HichwaAbstract:: We examined regional cerebral blood flow (rCBF) during a long-term recognition memory task for words in schizophrenic patients and in healthy subjects using positron emission tomography (PET). The task was designed so that performance scores were similar in the patient and control subjects. This memory retrieval task did not increase rCBF in the patients' prefrontal cortex, precuneus and cerebellum as much as it did in the control group. These results point to a dysfunctional corticocerebellar circuit leading to poorly coordinated mental activity ('cognitive Dysmetria'), which could explain the broad range of schizophrenic symptoms. In addition, other brain areas were more activated by the task in the patient group than in the control group and may form a compensatory network performing the memory retrieval task by assisting or replacing the dysfunctional cortico-cerebellar circuit.
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cognitive Dysmetria as an integrative theory of schizophrenia a dysfunction in cortical subcortical cerebellar circuitry
Schizophrenia Bulletin, 1998Co-Authors: Nancy C Andreasen, Sergio Paradiso, Daniel S OlearyAbstract:: Earlier efforts to localize the symptoms of schizophrenia in a single brain region have been replaced by models that postulate a disruption in parallel distributed or dynamic circuits. Based on empirical data derived from both magnetic resonance and positron emission tomography, we have developed a model that implicates connectivity among nodes located in prefrontal regions, the thalamic nuclei, and the cerebellum. A disruption in this circuitry produces "cognitive Dysmetria," difficulty in prioritizing, processing, coordinating, and responding to information. This "poor mental coordination" is a fundamental cognitive deficit in schizophrenia and can account for its broad diversity of symptoms.
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schizophrenia and cognitive Dysmetria a positron emission tomography study of dysfunctional prefrontal thalamic cerebellar circuitry
Proceedings of the National Academy of Sciences of the United States of America, 1996Co-Authors: Nancy C Andreasen, Daniel S Oleary, G L Watkins, L Boles L Ponto, T Cizadlo, Stephan Arndt, Karim Rezai, Richard D HichwaAbstract:Abstract Patients suffering from schizophrenia display subtle cognitive abnormalities that may reflect a difficulty in rapidly coordinating the steps that occur in a variety of mental activities. Working interactively with the prefrontal cortex, the cerebellum may play a role in coordinating both motor and cognitive performance. This positron-emission tomography study suggests the presence of a prefrontal-thalamic-cerebellar network that is activated when normal subjects recall complex narrative material, but is dysfunctional in schizophrenic patients when they perform the same task. These results support a role for the cerebellum in cognitive functions and suggest that patients with schizophrenia may suffer from a "cognitive Dysmetria" due to dysfunctional prefrontal-thalamic-cerebellar circuitry.