scholarly journals Are age-related changes in cortical motor representations linked with facilitation/inhibition in the primary motor cortex?

2019 ◽  
Vol 13 ◽  
Author(s):  
Melina Hehl ◽  
Stephan Swinnen ◽  
Koen Cuypers
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Cortical Motor ◽  
Age Related ◽  
Motor Representations ◽  
Age Related Changes

scholarly journals Age-related changes in the human primary motor cortex: A macroscopic and microscopic study

2021 ◽  
Vol 12 (11) ◽  
pp. 174-179
Author(s):  
Anne George ◽  
Usha K K
Keyword(s):  
Motor Cortex ◽  
Gray Matter ◽  
Primary Motor Cortex ◽  
Pyramidal Cells ◽  
Precentral Gyrus ◽  
Age Group ◽  
Central Sulcus ◽  
Maximum Width ◽  
Age Related ◽  
Age Related Changes

Background: Cerebral hemisphere has outer gray matter and inner white matter. The cerebrum is folded into gyri and sulci in order to accommodate it in the skull. The thickness of the gray matter varies at sulci and gyri and the mean thickness may be from 1.5 mm to 4.0 mm. Aims and Objectives: (1) To demonstrate the cells and laminar architecture of the primary motor cortex with different stains. (2) To find out the age-related changes in the thickness of the primary motor cortex and the depth of the central sulcus. Materials and Methods: Cross-sectional study was done using 50 adult human brains and 10 fetal brains obtained from the Department of Forensic medicine and OBG, respectively, in a Government Medical College in Kerala during 2001–2003. At autopsy, the central sulcus and the precentral gyrus were identified. Depth of central sulcus and thickness of precentral gyrus, in upper, middle, and lower parts were measured using Vernier calipers. Tissue specimens were taken from the precentral gyrus and after fixation in 10% formalin, hematoxylin, and eosin-stained slides were prepared and viewed under a light microscope identifying six laminae. Using an oculo micrometer, width of the six laminae were measured. Pyramidal cells and stellate cells were observed and their size measured. Results: Depth of the central sulcus was more on the right side but it was minimal on the middle part of both sides. The thickness of the precentral gyrus varied from 1 to 6 mm. Maximum thickness of 6 mm was found in the middle and lower parts in the 21–30 age group. Lamina 5 was the widest of all laminae. Maximum width of 1000 μ was noted in the 41–50 age group. Conclusion: Grey matter thickness of 1-6 mm noted in this study was comparable with other studies. Pyramidal cells of varying sizes were seen in all sections with different staining methods. It was confirmed that neuronal loss is inevitable as age advances.

scholarly journals Age-Related Changes in the Primary Motor Cortex of Newborn to Adult Domestic Pig Sus scrofa domesticus

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 2019
Author(s):  
Salvatore Desantis ◽  
Serena Minervini ◽  
Lorenzo Zallocco ◽  
Bruno Cozzi ◽  
Andrea Pirone
Keyword(s):  
Animal Model ◽  
Motor Cortex ◽  
Calcium Binding ◽  
Sus Scrofa ◽  
Primary Motor Cortex ◽  
Morphological Changes ◽  
Neural Cells ◽  
Age Related ◽  
Cell Layers ◽  
Sus Scrofa Domesticus

The pig has been increasingly used as a suitable animal model in translational neuroscience. However, several features of the fast-growing, immediately motor-competent cerebral cortex of this species have been adequately described. This study analyzes the cytoarchitecture of the primary motor cortex (M1) of newborn, young and adult pigs (Sus scrofa domesticus). Moreover, we investigated the distribution of the neural cells expressing the calcium-binding proteins (CaBPs) (calretinin, CR; parvalbumin, PV) throughout M1. The primary motor cortex of newborn piglets was characterized by a dense neuronal arrangement that made the discrimination of the cell layers difficult, except for layer one. The absence of a clearly recognizable layer four, typical of the agranular cortex, was noted in young and adult pigs. The morphometric and immunohistochemical analyses revealed age-associated changes characterized by (1) thickness increase and neuronal density (number of cells/mm2 of M1) reduction during the first year of life; (2) morphological changes of CR-immunoreactive neurons in the first months of life; (3) higher density of CR- and PV-immunopositive neurons in newborns when compared to young and adult pigs. Since most of the present findings match with those of the human M1, this study strengthens the growing evidence that the brain of the pig can be used as a potentially valuable translational animal model during growth and development.

scholarly journals Age-related changes in causal interactions between cortical motor regions during hand grip

NeuroImage ◽  
2012 ◽  
Vol 59 (4) ◽  
pp. 3398-3405 ◽  
Author(s):  
Marie-Hélène Boudrias ◽  
Carla Sá Gonçalves ◽  
Will D. Penny ◽  
Chang-hyun Park ◽  
Holly E. Rossiter ◽  
...  
Keyword(s):  
Hand Grip ◽  
Cortical Motor ◽  
Age Related ◽  
Age Related Changes

scholarly journals Plasticity of the Cortical Motor System

2008 ◽  
Vol 20 (1) ◽  
pp. 5-22 ◽  
Author(s):  
Bogdan Sadowski
Keyword(s):  
Motor Cortex ◽  
Motor System ◽  
Primary Motor Cortex ◽  
Pyramidal Neurons ◽  
Pyramidal Cells ◽  
Long Term Potentiation ◽  
Skill Learning ◽  
Dynamic Features ◽  
Cortical Motor

Plasticity of the Cortical Motor SystemThe involvement of brain plastic mechanisms in the control of motor functions under normal and pathological conditions is described. These mechanisms are based on a similar principle as the neuronal models of neuronal plasticity - long-term potentiation (LTP), and long-term depression (LTD). In the motor cortex, LTP-like phenomena play a role in strengthening synaptic connections between pyramidal neurons. LTD is important for the elimination of unnecessary inputs to the cortex. The dynamic features of the primary motor cortex activity depend on particular neuronal interconnectivity within this area. The pyramidal cells send horizontal collaterals to adjacent subregions of the primary motor cortex, and so can either excite or inhibit remote pyramidal cells. These connections can expand or shrink depending on actual physiological demands, and play a role in skill learning.

Laterality of Movement-Related Activity Reflects Transformation of Coordinates in Ventral Premotor Cortex and Primary Motor Cortex of Monkeys

2007 ◽  
Vol 98 (4) ◽  
pp. 2008-2021 ◽  
Author(s):  
Kiyoshi Kurata
Keyword(s):  
Motor Cortex ◽  
Neuronal Activity ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Visuomotor Transformation ◽  
Related Activity ◽  
Reaching Task ◽  
Ventral Premotor Cortex ◽  
Cortical Motor ◽  
Target Locations

The ventral premotor cortex (PMv) and the primary motor cortex (MI) of monkeys participate in various sensorimotor integrations, such as the transformation of coordinates from visual to motor space, because the areas contain movement-related neuronal activity reflecting either visual or motor space. In addition to relationship to visual and motor space, laterality of the activity could indicate stages in the visuomotor transformation. Thus we examined laterality and relationship to visual and motor space of movement-related neuronal activity in the PMv and MI of monkeys performing a fast-reaching task with the left or right arm, toward targets with visual and motor coordinates that had been dissociated by shift prisms. We determined laterality of each activity quantitatively and classified it into four types: activity that consistently depended on target locations in either head-centered visual coordinates (V-type) or motor coordinates (M-type) and those that had either differential or nondifferential activity for both coordinates (B- and N-types). A majority of M-type neurons in the areas had preferences for reaching movements with the arm contralateral to the hemisphere where neuronal activity was recorded. In contrast, most of the V-type neurons were recorded in the PMv and exhibited less laterality than the M-type. The B- and N-types were recorded in the PMv and MI and exhibited intermediate properties between the V- and M-types when laterality and correlations to visual and motor space of them were jointly examined. These results suggest that the cortical motor areas contribute to the transformation of coordinates to generate final motor commands.

scholarly journals Sarm1 deletion suppresses TDP-43-linked motor neuron degeneration and cortical spine loss

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Matthew A. White ◽  
Ziqiang Lin ◽  
Eugene Kim ◽  
Christopher M. Henstridge ◽  
Emiliano Pena Altamira ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Mouse Model ◽  
Motor Neuron ◽  
Transgenic Mouse ◽  
Entorhinal Cortex ◽  
Wallerian Degeneration ◽  
Axonal Degeneration ◽  
Primary Motor Cortex ◽  
Neuronal Degeneration ◽  
Age Related

Abstract Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative condition that primarily affects the motor system and shares many features with frontotemporal dementia (FTD). Evidence suggests that ALS is a ‘dying-back’ disease, with peripheral denervation and axonal degeneration occurring before loss of motor neuron cell bodies. Distal to a nerve injury, a similar pattern of axonal degeneration can be seen, which is mediated by an active axon destruction mechanism called Wallerian degeneration. Sterile alpha and TIR motif-containing 1 (Sarm1) is a key gene in the Wallerian pathway and its deletion provides long-term protection against both Wallerian degeneration and Wallerian-like, non-injury induced axonopathy, a retrograde degenerative process that occurs in many neurodegenerative diseases where axonal transport is impaired. Here, we explored whether Sarm1 signalling could be a therapeutic target for ALS by deleting Sarm1 from a mouse model of ALS-FTD, a TDP-43Q331K, YFP-H double transgenic mouse. Sarm1 deletion attenuated motor axon degeneration and neuromuscular junction denervation. Motor neuron cell bodies were also significantly protected. Deletion of Sarm1 also attenuated loss of layer V pyramidal neuronal dendritic spines in the primary motor cortex. Structural MRI identified the entorhinal cortex as the most significantly atrophic region, and histological studies confirmed a greater loss of neurons in the entorhinal cortex than in the motor cortex, suggesting a prominent FTD-like pattern of neurodegeneration in this transgenic mouse model. Despite the reduction in neuronal degeneration, Sarm1 deletion did not attenuate age-related behavioural deficits caused by TDP-43Q331K. However, Sarm1 deletion was associated with a significant increase in the viability of male TDP-43Q331K mice, suggesting a detrimental role of Wallerian-like pathways in the earliest stages of TDP-43Q331K-mediated neurodegeneration. Collectively, these results indicate that anti-SARM1 strategies have therapeutic potential in ALS-FTD.

Functional Connectivity Between Secondary and Primary Motor Areas Underlying Hand–Foot Coordination

2007 ◽  
Vol 98 (1) ◽  
pp. 414-422 ◽  
Author(s):  
Winston D. Byblow ◽  
James P. Coxon ◽  
Cathy M. Stinear ◽  
Melanie K. Fleming ◽  
Garry Williams ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Motor Cortex ◽  
Muscle Activation ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Hand Movement ◽  
Physiological Basis ◽  
Activation Conditions ◽  
Motor Representations ◽  
Motor Areas

Coincident hand and foot movements are more reliably performed in the same direction than in opposite directions. Using transcranial magnetic stimulation (TMS) to assess motor cortex function, we examined the physiological basis of these movements across three novel experiments. Experiment 1 demonstrated that upper limb corticomotor excitability changed in a way that facilitated isodirectional movements of the hand and foot, during phasic and isometric muscle activation conditions. Experiment 2 demonstrated that motor cortex inhibition was modified with active, but not passive, foot movement in a manner that facilitated hand movement in the direction of foot movement. Together, these findings demonstrate that the coupling between motor representations within motor cortex is activity dependent. Because there are no known connections between hand and foot areas within primary motor cortex, experiment 3 used a dual-coil paired-pulse TMS protocol to examine functional connectivity between secondary and primary motor areas during active ankle dorsiflexion and plantarflexion. Dorsal premotor cortex (PMd) and supplementary motor area (SMA) conditioning, but not ventral premotor cortex (PMv) conditioning, produced distinct phases of task-dependent modulation of excitability of forearm representations within primary motor cortex (M1). Networks involving PMd–M1 facilitate isodirectional movements of hand and foot, whereas networks involving SMA–M1 facilitate corticomotor pathways nonspecifically, which may help to stabilize posture during interlimb coordination. These results may have implications for targeted neurorehabilitation after stroke.

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