Dynamic Changes in Upper-Limb Corticospinal Excitability during a ‘Pro-/Anti-saccade’ Double-Choice Task

Simulated military operational stress (SMOS) provides a useful model to better understand resilience in humans as the stress associated with caloric restriction, sleep deficits, and fatiguing exertion degrades physical and cognitive performance. Habitual physical activity may confer resilience against these stressors by promoting favorable use-dependent neuroplasticity, but it is unclear how physical activity, resilience, and corticospinal excitability (CSE) relate during SMOS. PURPOSE: To examine associations between corticospinal excitability, physical activity, and physical performance during SMOS. METHODS: Fifty-three service members (age: 26±5yrs, 13 women) completed a five day and night intervention composed of familiarization, baseline, SMOS (two nights/days), and recovery days. During SMOS, participants performed rigorous physical and cognitive activities while receiving half of normal sleep (two 2h blocks) and caloric requirements. Lower and upper limb CSE were determined with transcranial magnetic stimulation (TMS) stimulus-response curves. Self-reported resilience, physical activity, military-specific physical performance (TMT) and endocrine factors were compared in individuals with high (HIGH) and low CSE based on a median split of lower limb CSE at baseline. RESULTS: HIGH had greater physical activity and better TMT performance throughout SMOS. Both groups maintained physical performance despite substantial psychophysiological stress. Physical activity, resilience, and TMT performance were directly associated with lower limb CSE. CONCLUSION: Individual differences in physical activity coincide with lower (but not upper) limb CSE. Such use-dependent corticospinal excitability directly relates to resilience and physical performance during SMOS. Future studies may use non-invasive neuromodulation to clarify the interplay among CSE, physical activity, and resilience and improve physical and cognitive performance.

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The Neurodynamic Decision Variable in Human Multi-alternative Perceptual Choice

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01347 ◽

2019 ◽

Vol 31 (2) ◽

pp. 262-277 ◽

Cited By ~ 3

Author(s):

Carmen Kohl ◽

Laure Spieser ◽

Bettina Forster ◽

Sven Bestmann ◽

Kielan Yarrow

Keyword(s):

Sequential Sampling ◽

Human Action ◽

Corticospinal Excitability ◽

Decision Variable ◽

Dynamic Changes ◽

Baseline Activity ◽

Decision Alternative ◽

Response Alternatives ◽

Action Representations ◽

Accumulator Models

The neural dynamics underpinning binary perceptual decisions and their transformation into actions are well studied, but real-world decisions typically offer more than two response alternatives. How does decision-related evidence accumulation dynamically influence multiple action representations in humans? The heightened conservatism required in multiple compared with binary choice scenarios suggests a mechanism that compensates for increased uncertainty when multiple choices are present by suppressing baseline activity. Here, we tracked action representations using corticospinal excitability during four- and two-choice perceptual decisions and modeled them using a sequential sampling framework. We found that the predictions made by leaky competing accumulator models to accommodate multiple choices (i.e., reduced baseline activity to compensate increased uncertainty) were borne out by dynamic changes in human action representations. This suggests a direct and continuous influence of interacting evidence accumulators, each favoring a different decision alternative, on downstream corticospinal excitability during complex choice.

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Corticospinal Excitability of the Lower Limb Muscles During the Anticipatory Postural Adjustments: A TMS Study During Dart Throwing

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2021.703377 ◽

2021 ◽

Vol 15 ◽

Author(s):

Amiri Matsumoto ◽

Nan Liang ◽

Hajime Ueda ◽

Keisuke Irie

Keyword(s):

Upper Limb ◽

Lower Limb ◽

Primary Motor Cortex ◽

Anticipatory Postural Adjustments ◽

Limb Movement ◽

Corticospinal Excitability ◽

Postural Adjustments ◽

Lower Limb Muscles ◽

Limb Muscles ◽

Dart Throwing

Objective: To investigate whether the changes in the corticospinal excitability contribute to the anticipatory postural adjustments (APAs) in the lower limb muscles when performing the ballistic upper limb movement of the dart throwing.Methods: We examined the primary motor cortex (M1) excitability of the lower limb muscles [tibialis anterior (TA) and soleus (SOL) muscles] during the APA phase by using transcranial magnetic stimulation (TMS) in the healthy volunteers. The surface electromyography (EMG) of anterior deltoid, triceps brachii, biceps brachii, TA, and SOL muscles was recorded and the motor evoked potential (MEP) to TMS was recorded in the TA muscle along with the SOL muscle. TMS at the hotspot of the TA muscle was applied at the timings immediately prior to the TA onset. The kinematic parameters including the three-dimensional motion analysis and center of pressure (COP) during the dart throwing were also assessed.Results: The changes in COP and EMG of the TA muscle occurred preceding the dart throwing, which involved a slight elbow flexion followed by an extension. The correlation analysis revealed that the onset of the TA muscle was related to the COP change and the elbow joint flexion. The MEP amplitude in the TA muscle, but not that in the SOL muscle, significantly increased immediately prior to the EMG burst (100, 50, and 0 ms prior to the TA onset).Conclusion: Our findings demonstrate that the corticospinal excitability of the TA muscle increases prior to the ballistic upper limb movement of the dart throwing, suggesting that the corticospinal pathway contributes to the APA in the lower limb in a muscle-specific manner.

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Influence of success rate representation on the changes of performance and the corticospinal excitability accompany a short‐term motor skill learning of a coordinated upper limb movement in humans

The FASEB Journal ◽

10.1096/fasebj.2021.35.s1.05522 ◽

2021 ◽

Vol 35 (S1) ◽

Author(s):

Nan Liang ◽

Hajime Ueda ◽

Amiri Matsumoto ◽

Reia Tanaka ◽

Keisuke Irie

Keyword(s):

Success Rate ◽

Upper Limb ◽

Motor Skill ◽

Limb Movement ◽

Corticospinal Excitability ◽

Skill Learning ◽

Motor Skill Learning ◽

Short Term ◽

Rate Representation

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Reflex Responses in Upper Limb Muscles to Cutaneous Stimuli

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/s0317167100048174 ◽

1993 ◽

Vol 20 (04) ◽

pp. 271-278 ◽

Cited By ~ 30

Author(s):

R. Chen

Keyword(s):

Stimulus Intensity ◽

Upper Limb ◽

Healthy Subjects ◽

Voluntary Contraction ◽

Cutaneous Reflexes ◽

Focal Lesions ◽

Normal Ranges ◽

Conduction Velocities ◽

Limb Muscles ◽

Biphasic Responses

ABSTRACT:Cutaneous reflexes in the upper limb were elicited by stimulating digital nerves and recorded by averaging rectified EMG from proximal and distal upper limb muscles during voluntary contraction. Distal muscles often showed a triphasic response: an inhibition with onset about 50 ms (Il) followed by a facilitation with onset about 60 ms (E2) followed by another inhibition with onset about 80 ms (12). Proximal muscles generally showed biphasic responses beginning with facilitation or inhibition with onset at about 40 ms. Normal ranges for the amplitude of these components were established from recordings on 22 arms of 11 healthy subjects. An attempt was made to determine the alterent fibers responsible for the various components by varying the stimulus intensity, by causing ischemic block of larger fibers and by estimating the afferent conduction velocities. The central pathways mediating these reflexes were examined by estimating central delays and by studying patients with focal lesions

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