scholarly journals Neurophysiological responses and adaptation following repeated bouts of maximal lengthening contractions in young and older adults

2019 ◽  
Vol 127 (5) ◽  
pp. 1224-1237 ◽  
Author(s):  
Jakob Škarabot ◽  
Paul Ansdell ◽  
John Temesi ◽  
Glyn Howatson ◽  
Stuart Goodall ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Muscle Damage ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Silent Period ◽  
Afferent Feedback ◽  
Lengthening Contractions ◽  
Corticospinal Pathway

A bout of maximal lengthening contractions is known to produce muscle damage, but confers protection against subsequent damaging bouts, with both tending to be lower in older adults. Neural factors contribute to this adaptation, but the role of the corticospinal pathway remains unclear. Twelve young (27 ± 5 yr) and 11 older adults (66 ± 4 yr) performed two bouts of 60 maximal lengthening dorsiflexions 2 weeks apart. Neuromuscular responses were measured preexercise, immediately postexercise, and at 24 and 72 h following both bouts. The initial bout resulted in prolonged reductions in maximal voluntary torque (MVC; immediately postexercise onward, P < 0.001) and increased creatine kinase (from 24 h onward, P = 0.001), with both responses being attenuated following the second bout ( P < 0.015), demonstrating adaptation. Smaller reductions in MVC following both bouts occurred in older adults ( P = 0.005). Intracortical facilitation showed no changes ( P ≥ 0.245). Motor-evoked potentials increased 24 and 72 h postexercise in young ( P ≤ 0.038). Torque variability ( P ≤ 0.041) and H-reflex size ( P = 0.024) increased, while short-interval intracortical inhibition (SICI; P = 0.019) and the silent period duration (SP) decreased ( P = 0.001) in both groups immediately postexercise. The SP decrease was smaller following the second bout ( P = 0.021), and there was an association between the change in SICI and reduction in MVC 24 h postexercise in young adults ( R = −0.47, P = 0.036). Changes in neurophysiological responses were mostly limited to immediately postexercise, suggesting a modest role in adaptation. In young adults, neural inhibitory changes are linked to the extent of MVC reduction, possibly mediated by the muscle damage–related afferent feedback. Older adults incurred less muscle damage, which has implications for exercise prescription. NEW & NOTEWORTHY This is the first study to have collectively assessed the role of corticospinal, spinal, and intracortical activity in muscle damage attenuation following repeated bouts of exercise in young and older adults. Lower levels of muscle damage in older adults are not related to their neurophysiological responses. Neural inhibition transiently changed, which might be related to the extent of muscle damage; however, the role of processes along the corticospinal pathway in the adaptive response is limited.

Mentoring and Career Development among University Faculty

1995 ◽  
Vol 177 (2) ◽  
pp. 31-45 ◽  
Author(s):  
Frank M. Perna ◽  
Bart M. Lerner ◽  
Michael T. Yura
Keyword(s):  
Professional Development ◽  
Older Adults ◽  
Young Adults ◽  
Career Development ◽  
Mentoring Relationships ◽  
University Faculty

Historically, the major theories of career development have directly or indirectly implicated the role of older adults in the personal and professional development of young adults. Increasily, attention has been focused on explaining the dynamics and effects of these mentoring relationships. In this article we review and discuss the research relating to mentoring and university faculty career development.

scholarly journals EXPLORING AGE, GENDER, AND RELATIONSHIP CLOSENESS DIFFERENCES IN RESPONSES TO IGNORED DISRESPECT

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S305-S305
Author(s):  
Jenessa C Steele ◽  
Amanda Chappell ◽  
Rachel Scott
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Age Differences ◽  
Negative Emotions ◽  
Age Groups ◽  
Emotional Responses ◽  
Younger Adults ◽  
Relationship Closeness ◽  
Close Condition

Abstract Emotional responses to disrespect tend to be negative (Hawkins, 2015). Little is known about how responses to disrespect vary across age groups and relationship closeness. It is unknown whether older adults have more emotional protection against disrespectful experiences, or are more deeply affected due to relationship closeness. Overall, we might expect that older adults react less negatively to disrespect compared to young adults, as they are more-skilled emotion regulators (Carstensen, 1991; English & Carstensen, 2014). We aimed to explore if, and under which circumstances, older adults are more or less sensitive to disrespect compared to younger adults. Three hundred participants responded to six scenarios illustrating ignored disrespect. Participants were randomly assigned to close or distant relationship disrespect scenarios. Relationship closeness was first determined by requesting participants identify a person in each layer of Kahn and Antonucci’s (1980) Social Convoy Model. Identified names were then automatically inserted into the six scenarios. Emotional responses and sensitivity to each scenario were recorded. Participants in the close condition reported more sensitivity to disrespect and negative emotions than participants in the distant condition. Females reported more sensitivity to disrespect and negative emotions than males. We did not find overwhelming support for age differences in responses to disrespect. A single scenario indicated younger participants more sensitive to disrespect than older participants. Findings suggest it is more hurtful to be disrespected by someone close to you and females may be more sensitive to disrespect than males. More research investigating the role of age in disrespect is needed.

Task-dependent changes of motor cortical network excitability during precision grip compared to isolated finger contraction

2012 ◽  
Vol 107 (5) ◽  
pp. 1522-1529 ◽  
Author(s):  
Nezha Kouchtir-Devanne ◽  
Charles Capaday ◽  
François Cassim ◽  
Philippe Derambure ◽  
Hervé Devanne
Keyword(s):  
Stimulus Intensity ◽  
Motor Evoked Potentials ◽  
Precision Grip ◽  
Silent Period ◽  
Intracortical Inhibition ◽  
Emg Activity ◽  
Maximum Slope ◽  
Corticospinal Pathway ◽  
Long Latency ◽  
Motor Cortical

The purpose of this study was to determine whether task-dependent differences in corticospinal pathway excitability occur in going from isolated contractions of the index finger to its coordinated activity with the thumb. Focal transcranial magnetic stimulation (TMS) was used to measure input-output (I/O) curves—a measure of corticospinal pathway excitability—of the contralateral first dorsal interosseus (FDI) muscle in 21 healthy subjects performing two isometric motor tasks: index abduction and precision grip. The level of FDI electromyographic (EMG) activity was kept constant across tasks. The amplitude of the FDI motor evoked potentials (MEPs) and the duration of FDI silent period (SP) were plotted against TMS stimulus intensity and fitted, respectively, to a Boltzmann sigmoidal function. The plateau level of the FDI MEP amplitude I/O curve increased by an average of 40% during the precision grip compared with index abduction. Likewise, the steepness of the curve, as measured by the value of the maximum slope, increased by nearly 70%. By contrast, all I/O curve parameters [plateau, stimulus intensity required to obtain 50% of maximum response ( S50), and slope] of SP duration were similar between the two tasks. Short- and long-latency intracortical inhibitions (SICI and LICI, respectively) were also measured in each task. Both measures of inhibition decreased during precision grip compared with the isolated contraction. The results demonstrate that the motor cortical circuits controlling index and thumb muscles become functionally coupled when the muscles are used synergistically and this may be due, at least in part, to a decrease of intracortical inhibition and an increase of recurrent excitation.

scholarly journals Oxytocin’s dynamic role across the lifespan

2021 ◽  
Author(s):  
Kristin Audunsdottir ◽  
Daniel S Quintana
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Signaling System ◽  
Treatment Target ◽  
Novel Treatment ◽  
Youth And Young Adults ◽  
And Behavior ◽  
Age Range ◽  
Signaling Activity

Older adults have been neglected in biobehavioral oxytocin research. Emerging research indicates that oxytocin signaling activity fluctuates over the lifespan, which suggests that results from studies investigating youth and young adults cannot be easily generalized to older adults. The recruitment of a wider age range of research participants using a variety of research tools is required to uncover the role of the oxytocin signaling system over the lifespan and may reveal novel treatment target candidates in older adults, beyond social cognition and behavior.

Corticomotor plasticity and learning of a ballistic thumb training task are diminished in older adults

2009 ◽  
Vol 107 (6) ◽  
pp. 1874-1883 ◽  
Author(s):  
Nigel C. Rogasch ◽  
Tamara J. Dartnall ◽  
John Cirillo ◽  
Michael A. Nordstrom ◽  
John G. Semmler
Keyword(s):  
Older Adults ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Training Task ◽  
Abductor Pollicis Brevis ◽  
Corticomotor Excitability ◽  
Old Adults ◽  
Young Subjects

This study examined changes in corticomotor excitability and plasticity after a thumb abduction training task in young and old adults. Electromyographic (EMG) recordings were obtained from right abductor pollicis brevis (APB, target muscle) and abductor digiti minimi (ADM, control muscle) in 14 young (18–24 yr) and 14 old (61–82 yr) adults. The training task consisted of 300 ballistic abductions of the right thumb to maximize peak thumb abduction acceleration (TAAcc). Transcranial magnetic stimulation (TMS) of the left primary motor cortex was used to assess changes in APB and ADM motor evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) before, immediately after, and 30 min after training. No differences in corticomotor excitability (resting and active TMS thresholds, MEP input-output curves) or SICI were observed in young and old adults before training. Motor training resulted in improvements in peak TAAcc in young (177% improvement, P < 0.001) and old (124%, P = 0.005) subjects, with greater improvements in young subjects ( P = 0.002). Different thumb kinematics were observed during task performance, with increases in APB EMG related to improvements in peak TAAcc in young ( r2 = 0.46, P = 0.008) but not old ( r2 = 0.09, P = 0.3) adults. After training, APB MEPs were 50% larger ( P < 0.001 compared with before) in young subjects, with no change after training in old subjects ( P = 0.49), suggesting reduced use-dependent corticomotor plasticity with advancing age. These changes were specific to APB, because no training-related change in MEP amplitude was observed in ADM. No significant association was observed between change in APB MEP and improvement in TAAcc with training in individual young and old subjects. SICI remained unchanged after training in both groups, suggesting that it was not responsible for the diminished use-dependent corticomotor plasticity for this task in older adults.

scholarly journals Effects of aging and emotional valence on item directed forgetting and source attributions

2021 ◽  
Author(s):  
Sara N. Gallant
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Emotional Valence ◽  
Directed Forgetting ◽  
Detection Task ◽  
Probe Detection ◽  
Intentional Forgetting ◽  
Effects Of Aging ◽  
Emotional Effects

Two experiments investigated the effects of aging and emotion on intentional forgetting. Experiment 1 compared 36 young (aged 18-28, M = 20.22, SD = 3.12) and 36 older adults (aged 65-85, M = 71.53, SD = 5.44) on item directed forgetting and source attributions (i.e., assigning a 'remember', 'forget', or 'new' tag during recognition) of positive, negative, and neutral words. Older adults' directed forgetting was reduced for positive words and their source attributions were differentially affected by emotion. Emotion had no effect on young adults' performance. Experiment 2 examined the role of attention in older adults' intentional forgetting. Thirty-six older adults (aged 65-91, M = 73.92, SD = 7.55) completed an emotional item directed forgetting task that incorporated a probe-detection task during encoding to assess the allocation of attention across valence conditions. Older adults again showed reduced directed forgetting for positive words and emotional effects in source attributions; however, results from the probe-detection task indicated the older adults' attention may not have been influenced by the emotional tone of stimuli during encoding.

scholarly journals Reduced corticospinal responses in older compared with younger adults during submaximal isometric, shortening, and lengthening contractions

2019 ◽  
Vol 126 (4) ◽  
pp. 1015-1031 ◽  
Author(s):  
Jakob Škarabot ◽  
Paul Ansdell ◽  
Callum G. Brownstein ◽  
Kirsty M. Hicks ◽  
Glyn Howatson ◽  
...  
Keyword(s):  
Older Adults ◽  
Motor Control ◽  
Motor Evoked Potentials ◽  
Production Capacity ◽  
Emg Activity ◽  
Younger Adults ◽  
Lengthening Contractions ◽  
Age Related ◽  
Age Dependent ◽  
Contraction Type

The aim of this study was to assess differences in motor performance, as well as corticospinal and spinal responses to transcranial magnetic and percutaneous nerve stimulation, respectively, during submaximal isometric, shortening, and lengthening contractions between younger and older adults. Fifteen younger [26 yr (SD 4); 7 women, 8 men] and 14 older [64 yr (SD 3); 5 women, 9 men] adults performed isometric and shortening and lengthening dorsiflexion on an isokinetic dynamometer (5°/s) at 25% and 50% of contraction type-specific maximums. Motor evoked potentials (MEPs) and H reflexes were recorded at anatomical zero. Maximal dorsiflexor torque was greater during lengthening compared with shortening and isometric contractions ( P < 0.001) but was not age dependent ( P = 0.158). However, torque variability was greater in older compared with young adults ( P < 0.001). Background electromyographic (EMG) activity was greater in older compared with younger adults ( P < 0.005) and was contraction type dependent ( P < 0.001). As evoked responses are influenced by both the maximal level of excitation and background EMG activity, the responses were additionally normalized {[MEP/maximum M wave (Mmax)]/root-mean-square EMG activity (RMS) and [H reflex (H)/Mmax]/RMS}. (MEP/Mmax)/RMS and (H/Mmax)/RMS were similar across contraction types but were greater in young compared with older adults ( P < 0.001). Peripheral motor conduction times were prolonged in older adults ( P = 0.003), whereas peripheral sensory conduction times and central motor conduction times were not age dependent ( P ≥ 0.356). These data suggest that age-related changes throughout the central nervous system serve to accommodate contraction type-specific motor control. Moreover, a reduction in corticospinal responses and increased torque variability seem to occur without a significant reduction in maximal torque-producing capacity during older age. NEW & NOTEWORTHY This is the first study to have explored corticospinal and spinal responses with aging during submaximal contractions of different types (isometric, shortening, and lengthening) in lower limb musculature. It is demonstrated that despite preserved maximal torque production capacity corticospinal responses are reduced in older compared with younger adults across contraction types along with increased torque variability during dynamic contractions. This suggests that the age-related corticospinal changes serve to accommodate contraction type-specific motor control.

scholarly journals Age and Social Support Seeking: Understanding the Role of Perceived Social Costs to Others

2018 ◽  
Vol 44 (7) ◽  
pp. 1104-1116 ◽  
Author(s):  
Li Jiang ◽  
Aimee Drolet ◽  
Heejung S. Kim
Keyword(s):  
Social Support ◽  
Older Adults ◽  
Young Adults ◽  
Age Differences ◽  
Age Groups ◽  
Social Costs ◽  
Different Types ◽  
Social Support Seeking ◽  
Support Seeking

We examined age differences in the use of different types of social support and the reasons for these differences. We found that older adults (age 60+) seek explicit social support less compared with young adults (age 18-25), but there is no difference in implicit social support seeking. Concerns about the potential social costs of seeking explicit support mediate the age differences in explicit social support seeking. Whereas young adults view this strategy as conferring more benefits than costs, older adults have a more balanced view of the costs and benefits of explicit social support seeking. Older and young adults do not differ in perceptions of the relative costs versus benefits of implicit social support seeking. Finally, we found older adults benefit more from implicit (vs. explicit) social support emotionally than young adults, which further explains why age groups differ in their use of explicit versus implicit social support.

Severe hypoxia affects exercise performance independently of afferent feedback and peripheral fatigue

2012 ◽  
Vol 112 (8) ◽  
pp. 1335-1344 ◽  
Author(s):  
Guillaume Y. Millet ◽  
Makii Muthalib ◽  
Marc Jubeau ◽  
Paul B. Laursen ◽  
Kazunori Nosaka
Keyword(s):  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Silent Period ◽  
Afferent Feedback ◽  
Cortical Inhibition ◽  
Severe Hypoxia ◽  
Peripheral Fatigue ◽  
M Wave ◽  
Functional Changes ◽  
Performance Reduction

To test the hypothesis that hypoxia centrally affects performance independently of afferent feedback and peripheral fatigue, we conducted two experiments under complete vascular occlusion of the exercising muscle under different systemic O2 environmental conditions. In experiment 1, 12 subjects performed repeated submaximal isometric contractions of the elbow flexor to exhaustion (RCTE) with inspired O2 fraction fixed at 9% (severe hypoxia, SevHyp), 14% (moderate hypoxia, ModHyp), 21% (normoxia, Norm), or 30% (hyperoxia, Hyper). The number of contractions (performance), muscle (biceps brachii), and prefrontal near-infrared spectroscopy (NIRS) parameters and high-frequency paired-pulse (PS100) evoked responses to electrical muscle stimulation were monitored. In experiment 2, 10 subjects performed another RCTE in SevHyp and Norm conditions in which the number of contractions, biceps brachii electromyography responses to electrical nerve stimulation (M wave), and transcranial magnetic stimulation responses (motor-evoked potentials, MEP, and cortical silent period, CSP) were recorded. Performance during RCTE was significantly reduced by 10–15% in SevHyp (arterial O2 saturation, SpO2 = ∼75%) compared with ModHyp (SpO2 = ∼90%) or Norm/Hyper (SpO2 > 97%). Performance reduction in SevHyp occurred despite similar 1) metabolic (muscle NIRS parameters) and functional (changes in PS100 and M wave) muscle states and 2) MEP and CSP responses, suggesting comparable corticospinal excitability and spinal and cortical inhibition between SevHyp and Norm. It is concluded that, in SevHyp, performance and central drive can be altered independently of afferent feedback and peripheral fatigue. It is concluded that submaximal performance in SevHyp is partly reduced by a mechanism related directly to brain oxygenation.

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