scholarly journals BOLD Coherence Reveals Segregated Functional Neural Interactions When Adapting to Distinct Torque Perturbations

2007 ◽  
Vol 97 (3) ◽  
pp. 2107-2120 ◽  
Author(s):  
Eugene Tunik ◽  
Paul J. Schmitt ◽  
Scott T. Grafton
Keyword(s):  
Basal Ganglia ◽  
Contextual Information ◽  
Natural World ◽  
Adaptive Responses ◽  
Response Preparation ◽  
Target Capture ◽  
Neural Processes ◽  
Neural Interactions ◽  
The Right ◽  
Level Analysis

In the natural world, we experience and adapt to multiple extrinsic perturbations. This poses a challenge to neural circuits in discriminating between different context-appropriate responses. Using event-related fMRI, we characterized the neural dynamics involved in this process by randomly delivering a position- or velocity-dependent torque perturbation to subjects’ arms during a target-capture task. Each perturbation was color-cued during movement preparation to provide contextual information. Although trajectories differed between perturbations, subjects significantly reduced error under both conditions. This was paralleled by reduced BOLD signal in the right dentate nucleus, the left sensorimotor cortex, and the left intraparietal sulcus. Trials included “NoGo” conditions to dissociate activity related to preparation from execution and adaptation. Subsequent analysis identified perturbation-specific neural processes underlying preparation (“NoGo”) and adaptation (“Go”) early and late into learning. Between-perturbation comparisons of BOLD magnitude revealed negligible differences for both preparation and adaptation trials. However, a network-level analysis of BOLD coherence revealed that by late learning, response preparation (“NoGo”) was attributed to a relative focusing of coherence within cortical and basal ganglia networks in both perturbation conditions, demonstrating a common network interaction for establishing arbitrary visuomotor associations. Conversely, late-learning adaptation (“Go”) was attributed to a focusing of BOLD coherence between a cortical–basal ganglia network in the viscous condition and between a cortical–cerebellar network in the positional condition. Our findings demonstrate that trial-to-trial acquisition of two distinct adaptive responses is attributed not to anatomically segregated regions, but to differential functional interactions within common sensorimotor circuits.

scholarly journals The Lamprey Forebrain – Evolutionary Implications

2021 ◽  
pp. 1-16
Author(s):  
Shreyas M. Suryanarayana ◽  
Juan Pérez-Fernández ◽  
Brita Robertson ◽  
Sten Grillner
Keyword(s):  
Basal Ganglia ◽  
Sensory Integration ◽  
Critical Role ◽  
Detailed Comparison ◽  
Common Ancestry ◽  
Dopamine System ◽  
Cortical Areas ◽  
Neural Processes ◽  
Living Group ◽  
Selection Of

The forebrain plays a critical role in a broad range of neural processes encompassing sensory integration and initiation/selection of behaviour. The forebrain functions through an interaction between different cortical areas, the thalamus, the basal ganglia with the dopamine system, and the habenulae. The ambition here is to compare the mammalian forebrain with that of the lamprey representing the oldest now living group of vertebrates, by a review of earlier studies. We show that the lamprey dorsal pallium has a motor, a somatosensory, and a visual area with retinotopic representation. The lamprey pallium was previously thought to be largely olfactory. There is also a detailed similarity between the lamprey and mammals with regard to other forebrain structures like the basal ganglia in which the general organisation, connectivity, transmitters and their receptors, neuropeptides, and expression of ion channels are virtually identical. These initially unexpected results allow for the possibility that many aspects of the basic design of the vertebrate forebrain had evolved before the lamprey diverged from the evolutionary line leading to mammals. Based on a detailed comparison between the mammalian forebrain and that of the lamprey and with due consideration of data from other vertebrate groups, we propose a compelling account of a pan-vertebrate schema for basic forebrain structures, suggesting a common ancestry of over half a billion years of vertebrate evolution.

Motor Subcircuits Mediating the Control of Movement Velocity: A PET Study

1998 ◽  
Vol 80 (4) ◽  
pp. 2162-2176 ◽  
Author(s):  
Robert S. Turner ◽  
Scott T. Grafton ◽  
John R. Votaw ◽  
Mahlon R. Delong ◽  
John M. Hoffman
Keyword(s):  
Motor Control ◽  
Basal Ganglia ◽  
Right Hemisphere ◽  
Movement Velocity ◽  
Rate Effects ◽  
Regression Slopes ◽  
The Right ◽  
Parietal Cortices ◽  
Linear Contrasts ◽  
Rate Of Movement

Turner, Robert S., Scott T. Grafton, John R. Votaw, Mahlon R. DeLong, and John M. Hoffman. Motor subcircuits mediating the control of movement velocity: a PET study. J. Neurophysiol. 80: 2162–2176, 1998. The influence of changes in the mean velocity of movement on regional cerebral blood flow (rCBF) was studied using positron emission tomography (PET) in nine healthy right-handed adults while they performed a smooth pursuit visuomanual tracking task. Images of relative rCBF were obtained while subjects moved a hand-held joystick to track the movement of a target at three different rates of a sinusoidal displacement (0.1, 0.4, and 0.7 Hz). Significant changes in rCBF between task conditions were detected using analysis of variance and weighted linear contrasts. The kinematics of arm and eye movements indicated that subjects performed tasks in a similar manner, particularly during the faster two tracking conditions. Significant increases in rCBF during arm movement (relative to an eye tracking only control condition) were detected in a widespread network of areas known for their involvement in motor control. The activated areas included primary sensorimotor (M1S1), dorsal and mesial premotor, and dorsal parietal cortices in the left hemisphere and to a lesser extent the sensorimotor and superior parietal cortices in the right hemisphere. Subcortically, activations were found in the left putamen, globus pallidus (GP), and thalamus, in the right basal ganglia, and in the right anterior cerebellum. Within the cerebral volume activated with movement, three areas had changes in rCBF that correlated positively with the rate of movement: left M1S1, left GP, and right anterior cerebellum. No movement-related sites had rCBF that correlated negatively with the rate of movement. Regressions of mean percent change (MPC) in rCBF onto mean hand velocity yielded two nonoverlapping subpopulations of movement-related loci, the three sites with significant rate effects and regression slopes steeper than 0.17 MPC⋅cm−1⋅s−1 and all other sites with nonsignificant rate effects and regression slopes below 0.1 MPC⋅cm−1⋅s−1. Moreover, the effects of movement per se and of movement velocity varied in magnitude independently. These results confirm previous reports that movement-related activations of M1S1 and cerebellum are sensitive to movement frequency or some covarying parameter of movement. The activation of GP with increasing movement velocity, not described in previous functional-imaging studies, supports the hypothesis that the basal ganglia motor circuit may be involved preferentially in controlling or monitoring the scale and/or dynamics of arm movements. The remaining areas that were activated equally for all movement rates may be involved in controlling higher level aspects of motor control that are independent of movement dynamics.

scholarly journals Response preparation involves a release of intracortical inhibition in task-irrelevant muscles

2020 ◽  
Author(s):  
Isaac N. Gomez ◽  
Kara Ormiston ◽  
Ian Greenhouse
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Index Finger ◽  
Intracortical Inhibition ◽  
Left Index Finger ◽  
Task Condition ◽  
Response Preparation ◽  
Action Preparation ◽  
The Right ◽  
Task Irrelevant

AbstractAction preparation involves widespread modulation of motor system excitability, but the precise mechanisms are unknown. In this study, we investigated whether intracortical inhibition changes in task-irrelevant muscle representations during action preparation. We used transcranial magnetic stimulation (TMS) combined with electromyography in healthy human adults to measure motor evoked potentials (MEPs) and cortical silent periods (CSPs) in task-irrelevant muscles during the preparatory period of simple delayed response tasks. In Experiment 1, participants responded with the left-index finger in one task condition and the right-index finger in another task condition, while MEPs and CSPs were measured from the contralateral non-responding and tonically contracted index finger. During Experiment 2, participants responded with the right pinky finger while MEPs and CSPs were measured from the tonically contracted left-index finger. In both experiments, MEPs and CSPs were compared between the task preparatory period and a resting intertrial baseline. The CSP duration during response preparation decreased from baseline in every case. A laterality difference was also observed in Experiment 1, with a greater CSP reduction during the preparation of left finger responses compared to right finger responses. MEP amplitudes showed no modulation during movement preparation in any of the three response conditions. These findings indicate cortical inhibition associated with task-irrelevant muscles is transiently released during action preparation and implicate a novel mechanism for the controlled and coordinated release of motor cortex inhibition.New & NoteworthyIn this study we observed the first evidence of a release of intracortical inhibition in task-irrelevant muscle representations during response preparation. We applied transcranial magnetic stimulation to elicit cortical silent periods in task-irrelevant muscles during response preparation and observed a consistent decrease in the silent period duration relative to a resting baseline. These findings address the question of whether cortical mechanisms underlie widespread modulation in motor excitability during response preparation.

A-67 Measuring Regional Cerebral Blood Flow with Single-Photon Emission Computed Tomography (SPECT) in Obsessive–Compulsive Disorder

2021 ◽  
Vol 36 (6) ◽  
pp. 1109-1109
Author(s):  
Sophia G Perez ◽  
Bailey McDonald ◽  
Samantha Spagna ◽  
Charles J Golden ◽  
Kristen Willeumier ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Basal Ganglia ◽  
Limbic System ◽  
Regional Cerebral Blood Flow ◽  
Healthy Controls ◽  
Regional Cerebral Blood ◽  
Obsessive Compulsive ◽  
Compulsive Disorder ◽  
The Right

Abstract Objective To identify regional cerebral blood flow (rCBF) differences between individuals with Obsessive–Compulsive Disorder (OCD) and healthy controls. Mehtods: Healthy controls (n = 81, Mage = 41.9, 53.0% female, 42.0% Caucasian) and persons diagnosed by psychiatric examination with OCD (n = 1020, Mage = 34.8, 33.6% female, 66.3% Caucasian) were selected from a deidentified adult clinical outpatient database. Those with comorbid diagnoses were included. Significant differences (alpha = 0.001) were found for age [t(1099) = −4.4], gender [χ2(2) = 25.7], and race [χ2(12) = 30.1] between groups and therefore were controlled for. Significant rCBF differences were noted in the cerebellum [left:F(1,1096) = 21.6; right:F(1,1096) = 18.3], limbic system [left:F(1,1096) = 12.2; right:F(1,1096) = 10.4], and basal ganglia [left:F(1,1096) = 18.6; right:F(1,1096) = 18.3]. Results Group means comparisons indicated higher perfusion in the cerebellum for the OCD group. Lower perfusion was found in the limbic system and basal ganglia in the OCD group. This study found higher perfusion in the cerebellum among the OCD group. Previous research found increased rCBF in the left cerebellum in OCD before pharmacotherapy. In the right cerebellum, increased rCBF was found among participants with early-onset OCD. Conclusion Overall, there is limited research on the cerebellum because of its use as a reference point. No research was found regarding the limbic system in OCD using SPECT; however, other neuroimaging found increased amygdala reactivity to emotional face stimuli. This study found lower perfusion in the basal ganglia among the OCD group. Previous research found hypoperfusion in the right; however, hypoperfusion in the left was not significant. Updated OCD and rCBF research with SPECT are needed. Limitations included the inclusion of comorbidities and use of DSM-IV-TR rather than DSM-5 diagnosis criteria.

Rights of Nature to Protect Human Rights in Times of Environmental Crisis

2020 ◽  
pp. 38-65
Author(s):  
Susana Borràs
Keyword(s):  
Human Rights ◽  
Well Being ◽  
Natural World ◽  
Environmental Crisis ◽  
Legal Systems ◽  
Environmental Laws ◽  
For Profit ◽  
Rights Of Nature ◽  
The Right

The well-being of humans and nature are inextricably linked. Nature is particularly mistreated in light of its characterization as merely “property” to be bought, sold, and ultimately degraded for profit. Reinforcing this misperception is the fact that modern environmental laws themselves implicitly accept this claim of “nature as property.” They legalize nature's destruction by dictating how much of the environment can be exploited and degraded, rather than as an integral ecological partner with its own rights to exist and thrive. Instead, we need laws grounded in the inherent rights of natural world to exist, thrive, and evolve. The article focuses on the transition from the ‘right to the environment' to a biocentric approach constructed around ‘rights of nature.' This transition is evident in various new legal instruments, which serve as models for legal systems that can steer us towards more robust and effective environmental laws.

The Context-Security Nexus in Ubiquitous Computing

2016 ◽  
pp. 660-679
Author(s):  
M. Fahim Ferdous Khan ◽  
Ken Sakamura
Keyword(s):  
Access Control ◽  
Ubiquitous Computing ◽  
Context Awareness ◽  
Contextual Information ◽  
Healthcare Services ◽  
Context Aware ◽  
Context Sensitive ◽  
Access Control Models ◽  
Spatio Temporal ◽  
The Right

Context-awareness is a quintessential feature of ubiquitous computing. Contextual information not only facilitates improved applications, but can also become significant security parameters – which in turn can potentially ensure service delivery not to anyone anytime anywhere, but to the right person at the right time and place. Specially, in determining access control to resources, contextual information can play an important role. Access control models, as studied in traditional computing security, however, have no notion of context-awareness; and the recent works in the nascent field of context-aware access control predominantly focus on spatio-temporal contexts, disregarding a host of other pertinent contexts. In this paper, with a view to exploring the relationship of access control and context-awareness in ubiquitous computing, the authors propose a comprehensive context-aware access control model for ubiquitous healthcare services. They explain the design, implementation and evaluation of the proposed model in detail. They chose healthcare as a representative application domain because healthcare systems pose an array of non-trivial context-sensitive access control requirements, many of which are directly or indirectly applicable to other context-aware ubiquitous computing applications.

Rights of Nature to Protect Human Rights in Times of Environmental Crisis

2017 ◽  
pp. 225-261
Author(s):  
Susana Borràs
Keyword(s):  
Human Rights ◽  
Well Being ◽  
Natural World ◽  
Environmental Crisis ◽  
Legal Systems ◽  
Environmental Laws ◽  
For Profit ◽  
Rights Of Nature ◽  
The Right

The well-being of humans and nature are inextricably linked. Nature is particularly mistreated in light of its characterization as merely “property” to be bought, sold, and ultimately degraded for profit. Reinforcing this misperception is the fact that modern environmental laws themselves implicitly accept this claim of “nature as property.” They legalize nature's destruction by dictating how much of the environment can be exploited and degraded, rather than as an integral ecological partner with its own rights to exist and thrive. Instead, we need laws grounded in the inherent rights of natural world to exist, thrive, and evolve. The article focuses on the transition from the ‘right to the environment' to a biocentric approach constructed around ‘rights of nature.' This transition is evident in various new legal instruments, which serve as models for legal systems that can steer us towards more robust and effective environmental laws.

Brain Imaging and Treatment Response in Spasmodic Torticollis

1988 ◽  
Vol 153 (3) ◽  
pp. 399-402 ◽  
Author(s):  
J. A. O. Besson ◽  
K. P. Ebmeier ◽  
H. G. Gemmell ◽  
P. F. Sharp ◽  
M. McFadyen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Basal Ganglia ◽  
Drug Treatment ◽  
Corpus Striatum ◽  
Spasmodic Torticollis ◽  
Flow Imaging ◽  
Blood Flow Imaging ◽  
The Right ◽  
Selection Of

A patient with spasms of the neck, occurring when he turned his head to the left, responded to treatment with benzhexol. Cerebral blood flow imaging demonstrated reduced uptake in the right corpus striatum compared with the left. The study demonstrates the presence of an abnormality in the basal ganglia; it also illustrates response to drug treatment. Cerebral blood flow imaging may be useful in the detection of basal ganglia abnormalities in spasmodic torticollis and assist in the selection of cases which should be targeted for treatment with drugs.

Distributed grey and white matter deficits in hyperkinetic disorder: MRI evidence for anatomical abnormality in an attentional network

2001 ◽  
Vol 31 (8) ◽  
pp. 1425-1435 ◽  
Author(s):  
S. OVERMEYER ◽  
E. T. BULLMORE ◽  
J. SUCKLING ◽  
A. SIMMONS ◽  
S. C. R. WILLIAMS ◽  
...  
Keyword(s):  
White Matter ◽  
Basal Ganglia ◽  
Large Scale ◽  
Grey Matter ◽  
Right Hemisphere ◽  
Hyperkinetic Disorder ◽  
Normal Children ◽  
Pyramidal Tracts ◽  
Icd 10 ◽  
The Right

Background. Previous neuroimaging studies of children with attention deficit hyperactivity disorder (ADHD) have demonstrated anatomic and functional abnormalities predominantly in frontal and striatal grey matter. Here we report the use of novel image analysis methods, which do not require prior selection of regions of interest, to characterize distributed morphological deficits of both grey and white matter associated with ADHD.Methods. Eighteen children with a refined phenotype of ADHD, who also met ICD-10 criteria for hyperkinetic disorder (mean age 10·4 years), and 16 normal children (mean age 10·3 years) were compared using magnetic resonance imaging. The groups were matched for handedness, sex, height, weight and head circumference. Morphological differences between groups were estimated by fitting a linear model at each voxel in standard space, applying a threshold to the resulting voxel statistic maps to generate clusters of spatially contiguous suprathreshold voxels, and testing cluster ‘mass’, or the sum of suprathreshold voxel statistics in each 2D cluster, by repeated random resampling of the data.Results. The hyperkinetic children had significant grey matter deficits in right superior frontal gyrus (Brodmann area (BA) 8/9), right posterior cingulate gyrus (BA 30) and the basal ganglia bilaterally (especially right globus pallidus and putamen). They also demonstrated significant central white matter deficits in the left hemisphere anterior to the pyramidal tracts and superior to the basal ganglia.Conclusions. This pattern of spatially distributed grey matter deficit in the right hemisphere is compatible with the hypothesis that ADHD is associated with disruption of a large scale neurocognitive network for attention. The left hemispheric white matter deficits may be due to dysmyelination.

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