A Model of Reaching Dynamics in Primary Motor Cortex

1998 ◽  
Vol 10 (1) ◽  
pp. 35-45 ◽  
Author(s):  
Sohie Lee Moody ◽  
David Zipser
Keyword(s):  
Neural Network ◽  
Motor Cortex ◽  
Recurrent Neural Network ◽  
Cortical Neurons ◽  
Primary Motor Cortex ◽  
Voluntary Movements ◽  
Reaching Movement ◽  
Time Constants ◽  
Movement Representation ◽  
The Individual

Features of virtually all voluntary movements are represented in the primary motor cortex. The movements can be ongoing, imminent, delayed, or imagined. Our goal was to investigate the dynamics of movement representation in the motor cortex. To do this we trained a fully recurrent neural network to continually output the direction and magnitude of movements required to reach randomly changing targets. Model neurons developed preferred directions and other properties similar to real motor cortical neurons. The key finding is that when the target for a reaching movement changes location, the ensemble representation of the movement changes nearly monotonically, and the individual neurons comprising the representation exhibit strong, nonmonotonic transients. These transients serve as internal recurrent signals that force the ensemble representation to change more rapidly than if it were limited by the time constants of individual neurons. These transients, if they exist, could be observed in experiments that require only slight modifications of the standard paradigm used to investigate movement representation in the motor cortex.

Functional properties of single neurons in the face primary motor cortex of the primate. II. Relations with trained orofacial motor behavior

1992 ◽  
Vol 67 (3) ◽  
pp. 759-774 ◽  
Author(s):  
G. M. Murray ◽  
B. J. Sessle
Keyword(s):  
Motor Cortex ◽  
Cortical Neurons ◽  
Primary Motor Cortex ◽  
Motor Behavior ◽  
Afferent Input ◽  
Single Neurons ◽  
Tongue Protrusion ◽  
Input And Output ◽  
The Face ◽  
Tongue Movements

1. The previous paper has described in detail the input and output features of single neurons located at sites within primate face motor cortex from which intracortical microstimulation (ICMS, less than or equal to 20 microA) evoked tongue movements at the lowest threshold ("tongue-MI" sites); for comparative purposes, we also reported on the input and output features of a smaller number of neurons recorded at sites from which ICMS could evoke jaw movements ("jaw-MI" sites), facial movements ("face-MI" sites), or, at a few sites, tongue movements and, at the same threshold intensity, either a jaw movement or a facial movement. 2. Our findings of an extensive and diverse representation of sites within face motor cortex of monkeys for the generation of elemental components of tongue movement, and the relatively few sites from which jaw-closing movements could be evoked, were consistent with our recent observations that reversible, cooling-induced inactivation of the face motor cortex severely impaired the performance by monkeys of a tongue-protrusion task but had only relatively minor effects on the performance of a biting task. In an attempt to establish a neuronal correlate for these different behavioral relations, the present study has documented the task-related activities of those single neurons that were characterized in the previous paper in terms of afferent input and ICMS-defined output features. 3. Each task required the development and maintenance by each monkey of a fixed force level for a minimum period of time to obtain a fruit-juice reward. During one or both of these tasks, we characterized the activities of 231 single face motor cortical neurons that were located at the above-mentioned ICMS-defined sites. Neurons were said to be related to a particular task if they showed statistically significant differences in firing rates during the task in comparison with a control pretrial period (PTP). 4. In tongue-MI, there was a significantly higher proportion of neurons (63% of 156 neurons tested) that were related to the tongue-protrusion task than to the biting task (15% of 65). However, in jaw-MI the proportion of neurons that were biting task-related (63% of 19) was significantly higher than the proportion related to the tongue-protrusion task (11% of 9); the proportion of biting task-related neurons at ICMS-defined jaw-closing sites was also higher than that at jaw-opening sites.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Classification of Eog Signal using Elman Recurrent Neural Network for Different Age Groups

2019 ◽  
Vol 9 (2S2) ◽  
pp. 842-847
Keyword(s):  
Neural Network ◽  
Recurrent Neural Network ◽  
Age Groups ◽  
Computer Interface ◽  
World Population ◽  
Age Group ◽  
The Individual ◽  
Elman Recurrent Neural Network ◽  
Male Subjects

Disabled people in the world population were increasing constantly, So need of rehabilitative system also increasing every day. To overcome such wretched condition, we can use the biosignal techniques to device the rehabilitative devices. Rehabilitative devices may be called as Brain Computer Interface (BCI) or Human Computer Interface (HCI). We studied the performances of ten male subjects between the age group of 18 to 25 using mean features and Elman Recurrent Neural Network (ERNN). We conducted our study with two different age group from 18 to 21 and 22 to 25. The average classification accuracy of 91.00%, 93.57% were attained for the age group of 18 to 21 and 22 to 25. From the individual analysis we identified that performances from the age group 22 to 25 were appreciated then that of the age group from 18 to 21. In between the study we analyzed that subject s from the age group 22 to 25 performed all the following five tasks neatly and accurately without any deviation and disturbance compared with age group from 18 to 21. Finally from the obtained result we concluded that subject from the age group 22 to 25 was higher than that of age group from 18 to 21.

scholarly journals Spiking recurrent neural networks represent task-relevant neural sequences in rule-dependent computation

2021 ◽  
Author(s):  
Xiaohe Xue ◽  
Michael M. Halassa ◽  
Zhe S. Chen
Keyword(s):  
Neural Network ◽  
Decision Making ◽  
Working Memory ◽  
Recurrent Neural Network ◽  
Cortical Neurons ◽  
Gradient Methods ◽  
Cognitive Tasks ◽  
Brain Functions ◽  
Neural Representations ◽  
Biological Constraints

AbstractPrefrontal cortical neurons play in important roles in performing rule-dependent tasks and working memory-based decision making. Motivated by experimental data, we develop an excitatory-inhibitory spiking recurrent neural network (SRNN) to perform a rule-dependent two-alternative forced choice (2AFC) task. We imposed several important biological constraints onto the SRNN, and adapted the spike frequency adaptation (SFA) and SuperSpike gradient methods to update the network parameters. These proposed strategies enabled us to train the SRNN efficiently and overcome the vanishing gradient problem during error back propagation through time. The trained SRNN produced rule-specific tuning in single-unit representations, showing rule-dependent population dynamics that strongly resemble experimentally observed data in rodent and monkey. Under varying test conditions, we further manipulated the parameters or configuration in computer simulation setups and investigated the impacts of rule-coding error, delay duration, weight connectivity and sparsity, and excitation/inhibition (E/I) balance on both task performance and neural representations. Overall, our modeling study provides a computational framework to understand neuronal representations at a fine timescale during working memory and cognitive control.Author SummaryWorking memory and decision making are fundamental cognitive functions of the brain, but the circuit mechanisms of these brain functions remain incompletely understood. Neuroscientists have trained animals (rodents or monkeys) to perform various cognitive tasks while simultaneously recording the neural activity from specific neural circuits. To complement the experimental investigations, computational modeling may provide an alternative way to examine the neural representations of neuronal assemblies during task behaviors. Here we develop and train a spiking recurrent neural network (SRNN) consisting of balanced excitatory and inhibitory neurons to perform the rule-dependent working memory tasks Our computer simulations produce qualitatively similar results as the experimental findings. Moreover, the imposed biological constraints on the trained network provide additional channel to investigate cell type-specific population responses, cortical connectivity and robustness. Our work provides a computational platform to investigate neural representations and dynamics of cortical circuits a fine timescale during complex cognitive tasks.

Cellular Mechanisms Preventing Sustained Activation of Cortex During Subcortical High-Frequency Stimulation

2006 ◽  
Vol 96 (2) ◽  
pp. 613-621 ◽  
Author(s):  
Karl J. Iremonger ◽  
Trent R. Anderson ◽  
Bin Hu ◽  
Zelma H. T. Kiss
Keyword(s):  
Motor Cortex ◽  
High Frequency ◽  
Cortical Neurons ◽  
Primary Motor Cortex ◽  
Brain Slices ◽  
Subcortical White Matter ◽  
High Frequency Stimulation ◽  
Cellular Mechanisms ◽  
Ventral Thalamus ◽  
Frequency Stimulation

Axonal excitation has been proposed as a key mechanism in therapeutic brain stimulation. In this study we examined how high-frequency stimulation (HFS) of subcortical white matter tracts projecting to motor cortex affects downstream postsynaptic responses in cortical neurons. Whole cell recordings were performed in the primary motor cortex (M1) and ventral thalamus of rat brain slices. In M1, neurons showed only an initial depolarization in response to HFS, after which the membrane potential returned to prestimulation levels. The prolonged suppression of excitation during stimulation was neither associated with GABAergic inhibition nor complete action potential failure in stimulated axons. Instead we found that HFS caused a depression of excitatory synaptic currents in postsynaptic neurons that was specific to the stimulated subcortical input. These data are consistent with the hypothesis that axonal HFS produces a functional deafferentation of postsynaptic targets likely from depletion of neurotransmitter.

Transcranial direct current stimulation effects on I-wave activity in humans

2011 ◽  
Vol 105 (6) ◽  
pp. 2802-2810 ◽  
Author(s):  
Nicolas Lang ◽  
Michael A. Nitsche ◽  
Michele Dileone ◽  
Paolo Mazzone ◽  
Javier De Andrés-Arés ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Cortical Neurons ◽  
Primary Motor Cortex ◽  
Motor Evoked Potential ◽  
Anodal Tdcs ◽  
Direct Current Stimulation ◽  
Cathodal Tdcs ◽  
Motor Cortex Excitability

Transcranial direct current stimulation (tDCS) of the human cerebral cortex modulates cortical excitability noninvasively in a polarity-specific manner: anodal tDCS leads to lasting facilitation and cathodal tDCS to inhibition of motor cortex excitability. To further elucidate the underlying physiological mechanisms, we recorded corticospinal volleys evoked by single-pulse transcranial magnetic stimulation of the primary motor cortex before and after a 5-min period of anodal or cathodal tDCS in eight conscious patients who had electrodes implanted in the cervical epidural space for the control of pain. The effects of anodal tDCS were evaluated in six subjects and the effects of cathodal tDCS in five subjects. Three subjects were studied with both polarities. Anodal tDCS increased the excitability of cortical circuits generating I waves in the corticospinal system, including the earliest wave (I1 wave), whereas cathodal tDCS suppressed later I waves. The motor evoked potential (MEP) amplitude changes immediately following tDCS periods were in agreement with the effects produced on intracortical circuitry. The results deliver additional evidence that tDCS changes the excitability of cortical neurons.

scholarly journals Gene expression changes of interconnected spared cortical neurons 7 days after ischemic infarct of the primary motor cortex in the rat

2012 ◽  
Vol 369 (1-2) ◽  
pp. 267-286 ◽  
Author(s):  
Edward T. R. Urban ◽  
Scott D. Bury ◽  
H. Scott Barbay ◽  
David J. Guggenmos ◽  
Yafeng Dong ◽  
...  
Keyword(s):  
Gene Expression ◽  
Motor Cortex ◽  
Cortical Neurons ◽  
Primary Motor Cortex ◽  
Ischemic Infarct

scholarly journals Forelimb movements evoked by optogenetic stimulation of the macaque motor cortex

2019 ◽  
Author(s):  
Hidenori Watanabe ◽  
Hiromi Sano ◽  
Satomi Chiken ◽  
Kenta Kobayashi ◽  
Yuko Fukata ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Cortical Neurons ◽  
Primary Motor Cortex ◽  
Viral Vector ◽  
Single Pulse ◽  
Brain Functions ◽  
Optogenetic Stimulation ◽  
Indispensable Tool ◽  
Cag Promoter ◽  
Forelimb Movements

AbstractOptogenetics has become an indispensable tool for investigating brain functions. Although non-human primates are particularly useful models for understanding the functions and dysfunctions of the human brain, application of optogenetics to non-human primates is still limited. In the present study, we generated an effective adeno-associated viral vector serotype DJ to express channelrhodopsin-2 (ChR2) under the control of a strong ubiquitous CAG promoter and injected into the somatotopically identified forelimb region of the primary motor cortex in macaque monkeys. ChR2 was strongly expressed around the injection sites, and optogenetic intracortical microstimulation (oICMS) through a homemade optrode induced prominent cortical activity: Even single-pulse, short duration oICMS evoked long-lasting repetitive firings of cortical neurons. In addition, oICMS elicited distinct forelimb movements and muscle activity, which were comparable to those elicited by conventional electrical ICMS. The present study removed obstacles to optogenetic manipulation of neuronal activity and behaviors in non-human primates.

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