scholarly journals Age-related Differences in Corticomotor Excitability and Inhibitory Processes during a Visuomotor RT Task

2012 ◽  
Vol 24 (5) ◽  
pp. 1253-1263 ◽  
Author(s):  
Hakuei Fujiyama ◽  
Mark R. Hinder ◽  
Matthew W. Schmidt ◽  
Christophe Tandonnet ◽  
Michael I. Garry ◽  
...  
Keyword(s):  
Older Adults ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Response Preparation ◽  
Younger Adults ◽  
Inhibitory Processes ◽  
Age Related ◽  
The Right

This study tested the postulation that change in the ability to modulate corticospinal excitability and inhibitory processes underlie age-related differences in response preparation and generation during tasks requiring either rapid execution of a motor action or actively withholding that same action. Younger (n = 13, mean age = 26.0 years) and older adults (n = 13, mean age = 65.5 years) performed an RT task in which a warning signal (WS) was followed by an imperative signal (IS) to which participants were required to respond with a rapid flexion of the right thumb (go condition) or withhold their response (no-go condition). We explored the neural correlates of response preparation, generation, and inhibition using single- and paired-pulse TMS, which was administered at various times between WS and IS (response preparation phase) and between IS and onset of response-related muscle activity in the right thumb (response generation phase). Both groups exhibited increases in motor-evoked potential amplitudes (relative to WS onset) during response generation; however, this increase began earlier and was more pronounced for the younger adults in the go condition. Moreover, younger adults showed a general decrease in short-interval intracortical inhibition during response preparation in both the go and no-go conditions, which was not observed in older adults. Importantly, correlation analysis suggested that for older adults the task-related increases of corticospinal excitability and intracortical inhibition were associated with faster RT. We propose that the declined ability to functionally modulate corticospinal activity with advancing age may underlie response slowing in older adults.

scholarly journals Characterising the balance between short-interval intracortical inhibition and short-interval intracortical facilitation in younger and older adults

2019 ◽  
Author(s):  
B.K. Rurak ◽  
G.R Hammond ◽  
H. Fujiyama ◽  
A.M. Vallence
Keyword(s):  
Older Adults ◽  
Short Interval ◽  
Conditioning Stimulus ◽  
Intracortical Inhibition ◽  
Manual Dexterity ◽  
Response Functions ◽  
Intracortical Facilitation ◽  
Younger Adults ◽  
Stimulus Response ◽  
Age Related

News and noteworthyMeasures of short-interval intracortical inhibition (SICI) and facilitation (SICF) reflect a balance between the excitability of inhibitory and facilitatory circuits in the motor cortex.SICI stimulus-response functions, measured with a range of conditioning stimulus intensities and two intervals (first peak and trough of the SICF function), were similar between younger and older adults, except at the shift from net inhibition to facilitation.Relationships between SICI and SICF and manual dexterity show that an inhibition-facilitation balance favouring inhibition is associated with better manual dexterity and a balance favouring facilitation is associated with poorer manual dexterity.AbstractResearch investigating age-related differences in intracortical inhibition acting within the primary motor cortex (M1) reports inconsistent results. Age-related changes in the balance of inhibition and facilitation acting within M1 might underlie the inconsistent findings. Here, paired-pulse TMS was used to examine the balance between short-interval intracortical inhibition (SICI) and short-interval intracortical facilitation (SICF) in younger (n=26) and older (n=21) adults. First, the inter-stimulus intervals (ISIs) that produced maximal and minimal SICF at the first peak and trough were identified for each individual. Second, SICI stimulus-response functions (conditioning stimulus (CS): 50–110% resting motor threshold) were determined at ISIs that produced maximal and minimal facilitation for each individual. When SICI was measured with the ISI that produced maximal facilitation, the shift from net inhibition to net facilitation occurred at a lower CS intensity in older than younger adults. When SICI was measured with the ISI that produced minimal facilitation, older adults showed a persistent net inhibition at the highest CS intensity, whereas younger adults showed a shift from net inhibition to net facilitation at high CS intensities. Relationships between SICI and SICF and manual dexterity were evident across all measures of the inhibition-facilitation balance, whereby a balance favouring inhibition is associated with better manual dexterity and a balance favouring facilitation is associated with poorer manual dexterity. These findings contribute to our understanding of age-related differences in intracortical inhibitory and facilitatory processes, as well as highlight the importance of considering the balance between inhibitory and facilitatory processes when measuring SICI and SICF.

scholarly journals Writing's Shadow: Corticospinal Activation during Letter Observation

2012 ◽  
Vol 24 (5) ◽  
pp. 1138-1148 ◽  
Author(s):  
Masahiro Nakatsuka ◽  
Mohamed Nasreldin Thabit ◽  
Satoko Koganemaru ◽  
Ippei Nojima ◽  
Hidenao Fukuyama ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Single Pulse ◽  
Random Order ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Motor Memory ◽  
F Wave ◽  
The Right

We can recognize handwritten letters despite the variability among writers. One possible strategy is exploiting the motor memory of orthography. By using TMS, we clarified the excitatory and inhibitory neural circuits of the motor corticospinal pathway that might be activated during the observation of handwritten letters. During experiments, participants looked at the handwritten or printed single letter that appeared in a random order. The excitability of the left and right primary motor cortex (M1) was evaluated by motor-evoked potentials elicited by single-pulse TMS. Short interval intracortical inhibition (SICI) of the left M1 was evaluated using paired-pulse TMS. F waves were measured for the right ulnar nerve. We found significant reduction of corticospinal excitability only for the right hand at 300–400 msec after each letter presentation without significant changes in SICI. This suppression is likely to be of supraspinal origin, because of no significant alteration in F-wave amplitudes. These findings suggest that the recognition of handwritten letters may include the implicit knowledge of “writing” in M1. The M1 activation associated with that process, which has been shown in previous neuroimaging studies, is likely to reflect the active suppression of the corticospinal excitability.

scholarly journals Long-interval intracortical inhibition is asymmetric in young but not older adults

2017 ◽  
Vol 118 (3) ◽  
pp. 1581-1590 ◽  
Author(s):  
A.-M. Vallence ◽  
E. Smalley ◽  
P. D. Drummond ◽  
G. R. Hammond
Keyword(s):  
Older Adults ◽  
Hemispheric Asymmetry ◽  
Intracortical Inhibition ◽  
Manual Dexterity ◽  
Hand Movements ◽  
Dominant Hand ◽  
Dominant Hemisphere ◽  
Younger Adults ◽  
Inhibitory Circuits ◽  
Age Related

Aging is typically accompanied by a decline in manual dexterity and handedness; the dominant hand executes tasks of manual dexterity more quickly and accurately than the nondominant hand in younger adults, but this advantage typically declines with age. Age-related changes in intracortical inhibitory processes might play a role in the age-related decline in manual dexterity. Long-interval intracortical inhibition (LICI) is asymmetric in young adults, with more sensitive and more powerful LICI circuits in the dominant hemisphere than in the nondominant hemisphere. Here we investigated whether the hemispheric asymmetry in LICI in younger adults persists in healthy older adults. Paired-pulse transcranial magnetic stimulation was used to measure LICI in the dominant and nondominant hemispheres of younger and older adults; LICI stimulus-response curves were obtained by varying conditioning stimulus intensity at two different interstimulus intervals [100 ms (LICI100) and 150 ms]. We have replicated the finding that LICI100 circuits are more sensitive and more powerful in the dominant than the nondominant hemisphere of young adults and extend this finding to show that the hemispheric asymmetry in LICI100 is lost with age. In the context of behavioral observations showing that dominant hand movements in younger adults are more fluent than nondominant hand movements in younger adults and dominant hand movements in older adults, we speculate a role of LICI100 in the age-related decline in manual dexterity. NEW & NOTEWORTHY In younger adults, more sensitive and more powerful long-interval intracortical inhibitory circuits are evident in the hemisphere controlling the more dexterous hand; this is not the case in older adults, for whom long-interval intracortical inhibitory circuits are symmetric and more variable than in younger adults. We speculate that the highly sensitive and powerful long-interval intracortical inhibition circuits in the dominant hemisphere play a role in manual dexterity.

scholarly journals Neurophysiological correlates of aging-related muscle weakness

2013 ◽  
Vol 110 (11) ◽  
pp. 2563-2573 ◽  
Author(s):  
Ela B. Plow ◽  
David A. Cunningham ◽  
Corin Bonnett ◽  
Dina Gohar ◽  
Mehmed Bayram ◽  
...  
Keyword(s):  
Older Adults ◽  
Muscle Weakness ◽  
Muscle Activation ◽  
Primary Motor Cortex ◽  
Biceps Brachii ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Voluntary Activation ◽  
Interhemispheric Inhibition

Muscle weakness associated with aging implicates central neural degeneration. However, role of the primary motor cortex (M1) is poorly understood, despite evidence that gains in strength in younger adults are associated with its adaptations. We investigated whether weakness of biceps brachii in aging analogously relates to processes in M1. We enrolled 20 young (22.6 ± 0.87 yr) and 28 old (74.79 ± 1.37 yr) right-handed participants. Using transcranial magnetic stimulation, representation of biceps in M1 was identified. We examined the effect of age and sex on strength of left elbow flexion, voluntary activation of biceps, corticospinal excitability and output, and short-interval intracortical and interhemispheric inhibition. Interhemispheric inhibition was significantly exaggerated in the old ( P = 0.047), while strength tended to be lower ( P = 0.075). Overall, women were weaker ( P < 0.001). Processes of M1 related to strength or voluntary activation of biceps, but only in older adults. Corticospinal excitability was lower in weaker individuals ( r = 0.38), and corticospinal output, intracortical inhibition and interhemispheric inhibition were reduced too in individuals who poorly activated biceps ( r = 0.43, 0.54 and 0.38). Lower intracortical inhibition may reflect compensation for reduced corticospinal excitability, allowing weaker older adults to spread activity in M1 to recruit synergists and attempt to sustain motor output. Exaggerated interhemispheric inhibition, however, conflicts with previous evidence, potentially related to greater callosal damage in our older sample, our choice of proximal vs. distal muscle and differing influence of measurement of inhibition in rest vs. active states of muscle. Overall, age-specific relation of M1 to strength and muscle activation emphasizes that its adaptations only emerge when necessitated, as in a weakening neuromuscular system in aging.

scholarly journals The Impact of Glucose on Corticospinal and Intracortical Excitability

2019 ◽  
Vol 9 (12) ◽  
pp. 339 ◽  
Author(s):  
Stephen L. Toepp ◽  
Claudia V. Turco ◽  
Mitchell B. Locke ◽  
Chiara Nicolini ◽  
Roshni Ravi ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Controlled Study ◽  
Glucose Response ◽  
Afferent Inhibition ◽  
Intracortical Excitability ◽  
The Impact

Neurotransmission is highly dependent on the availability of glucose-derived energy, although it is unclear how glucose availability modulates corticospinal and intracortical excitability as assessed via transcranial magnetic stimulation (TMS). In this double-blinded placebo-controlled study, we tested the effect of acute glucose intake on motor-evoked potential (MEP) recruitment curves, short-interval intracortical inhibition (SICI), short-latency afferent inhibition (SAI) and long-latency afferent inhibition (LAI). Eighteen healthy males participated in four sessions. Session 1 involved acquisition of an individualized blood glucose response curve. This allowed measurements to be time-locked to an individualized glucose peak after consuming one of three drinks during the subsequent three sessions. Participants were administered a 300 mL concealed solution containing 75 g of glucose, sucralose, or water in separate sessions. Dependent measures were assessed at baseline and twice after drinking the solution. Secondary measures included blood glucose and mean arterial pressure. Corticospinal excitability and blood pressure increased following the drink across all treatments. No changes were observed in SICI, SAI or LAI. There was no rise in corticospinal excitability that was specific to the glucose drink, suggesting that acute changes in glucose levels do not necessarily alter TMS measures of corticospinal or intracortical excitability.

Age-Related Differences in Motivational Integration and Cognitive Control

2019 ◽  
Author(s):  
Debbie Marianne Yee ◽  
Sarah L Adams ◽  
Asad Beck ◽  
Todd Samuel Braver
Keyword(s):  
Older Adults ◽  
Decision Making ◽  
Cognitive Control ◽  
Task Performance ◽  
Cognitive Task ◽  
Monetary Reward ◽  
Potential Candidate ◽  
Younger Adults ◽  
Age Related ◽  
Cognitive Task Performance

Motivational incentives play an influential role in value-based decision-making and cognitive control. A compelling hypothesis in the literature suggests that the brain integrates the motivational value of diverse incentives (e.g., motivational integration) into a common currency value signal that influences decision-making and behavior. To investigate whether motivational integration processes change during healthy aging, we tested older (N=44) and younger (N=54) adults in an innovative incentive integration task paradigm that establishes dissociable and additive effects of liquid (e.g., juice, neutral, saltwater) and monetary incentives on cognitive task performance. The results reveal that motivational incentives improve cognitive task performance in both older and younger adults, providing novel evidence demonstrating that age-related cognitive control deficits can be ameliorated with sufficient incentive motivation. Additional analyses revealed clear age-related differences in motivational integration. Younger adult task performance was modulated by both monetary and liquid incentives, whereas monetary reward effects were more gradual in older adults and more strongly impacted by trial-by-trial performance feedback. A surprising discovery was that older adults shifted attention from liquid valence toward monetary reward throughout task performance, but younger adults shifted attention from monetary reward toward integrating both monetary reward and liquid valence by the end of the task, suggesting differential strategic utilization of incentives. Together these data suggest that older adults may have impairments in incentive integration, and employ different motivational strategies to improve cognitive task performance. The findings suggest potential candidate neural mechanisms that may serve as the locus of age-related change, providing targets for future cognitive neuroscience investigations.

Internet Navigation Skills for Financial Management: Associations with Age, Neurocognitive Performance, and Functional Capacity

2020 ◽  
Author(s):  
Samina Rahman ◽  
Victoria Kordovski ◽  
Savanna Tierney ◽  
Steven Paul Woods
Keyword(s):  
Older Adults ◽  
Functional Capacity ◽  
Financial Management ◽  
Internet Banking ◽  
Online Banking ◽  
Neurocognitive Performance ◽  
Younger Adults ◽  
Neurocognitive Functions ◽  
Age Related ◽  
Use Factors

Objective: Online banking is becoming increasingly common among older adults, whomay experience difficulties effectively navigating this instrumental technology. Thisstudy examined age effects on a performance-based Internet banking task and itsassociation with neurocognitive ability and functional capacity in older and youngeradults. Method: Thirty-five older adults and 50 younger adults completed anexperimenter-controlled online banking measure in which they independentlyperformed a series of naturalistic financial tasks (e.g., account transfers, bill paying).Participants also completed a standardized battery of neuropsychological tests andmeasures of functional capacity. Results: Older adults were markedly slower and lessaccurate in completing the Internet-based banking task, which was not confounded byother demographic, mood, or computer use factors. Higher scores on measures ofneurocognition and financial functional capacity were both strongly associated withhigher Internet-based banking task accuracy scores and quicker completion times inthe older, but not the younger adults. Conclusions: Findings suggest that older adultsexperience difficultly quickly and accurately navigating online banking platforms, whichmay be partly related to age-related declines in neurocognitive functions and basicfinancial capacity. Future studies might examine whether neurocognitive approaches toremediation and compensation can be used to improve online banking capacity inolder adults.

scholarly journals Positive Emodiversity Buffers the Association Between Stress and Depressive Symptoms

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 653-653
Author(s):  
Lizbeth Benson ◽  
Anthony Ong
Keyword(s):  
Older Adults ◽  
Depressive Symptoms ◽  
Life Span ◽  
Daily Diary ◽  
National Study ◽  
Younger Adults ◽  
Shannon's Entropy ◽  
Daily Experiences ◽  
Age Related ◽  
Optimal Functioning

Abstract Intensive measurements of individuals’ experiences allow for identifying patterns of functioning that may be markers of resilience, and whether such patterns differ across the life span. Using 8 daily diary reports collected in the second burst of the National Study of Daily Experiences (NSDE, n=848, age 34-84; 55%female), we examined whether positive emodiversity (Shannon’s entropy) attenuated the association between cumulative stressor exposure and depressive symptoms, and age-related differences therein. Results indicated age moderated the extent to which positive emodiversity attenuated the association between stress and depressive symptoms (b=0.11, p &lt; .05). The attenuated association was strongest for younger adults with higher positive emodiversity, compared to those with lower positive emodiversity. For older adults, the association between stress and depressive symptoms was relatively similar regardless of their positive emodiversity. Implications pertain to for whom and in what contexts specific types of dynamic emotion experiences may promote optimal functioning and resilience.

scholarly journals The effect of age on postural and cognitive task performance while using vibrotactile feedback

2015 ◽  
Vol 113 (7) ◽  
pp. 2127-2136 ◽  
Author(s):  
Chia-Cheng Lin ◽  
Susan L. Whitney ◽  
Patrick J. Loughlin ◽  
Joseph M. Furman ◽  
Mark S. Redfern ◽  
...  
Keyword(s):  
Older Adults ◽  
Cognitive Performance ◽  
Center Of Pressure ◽  
Cognitive Task ◽  
Balance Performance ◽  
Vibrotactile Feedback ◽  
Younger Adults ◽  
Age Related ◽  
Trunk Tilt ◽  
Effect Of Age

Vibrotactile feedback (VTF) has been shown to improve balance performance in healthy people and people with vestibular disorders in a single-task experimental condition. It is unclear how age-related changes in balance affect the ability to use VTF and if there are different attentional requirements for old and young adults when using VTF. Twenty younger and 20 older subjects participated in this two-visit study to examine the effect of age, VTF, sensory condition, cognitive task, duration of time, and visit on postural and cognitive performance. Postural performance outcome measures included root mean square of center of pressure (COP) and trunk tilt, and cognitive performance was assessed using the reaction time (RT) from an auditory choice RT task. The results showed that compared with younger adults, older adults had an increase in COP in fixed platform conditions when using VTF, although they were able to reduce COP during sway-referenced platform conditions. Older adults also did not benefit fully from using VTF in their first session. The RTs for the secondary cognitive tasks increased significantly while using the VTF in both younger and older adults. Older adults had a larger increase compared with younger adults, suggesting that greater attentional demands were required in older adults when using VTF information. Future training protocols for VTF should take into consideration the effect of aging.

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