Physical Activity, Nutrition, Cognition, Neurophysiology, and Short-Time Synaptic Plasticity in Healthy Older Adults: A Cross-Sectional Study

Abstract

The aging brain undergoes remodeling processes because of biological and environmental factors. To counteract brain aging, neuronal plasticity should be preserved. The aim of this study was to test if the capacity of generating short-time synaptic plasticity in older adults may be related to either physical activity, nutritional status, cognition, or neurophysiological activity. Thirty-six participants (mean age 73.3 ± 5.9 years) received transcranial magnetic stimulation in combination with peripheral nerve stimulation to experimentally induce short-time synaptic plasticity by paired associative stimulation (PAS). Adaptations in neuronal excitability were assessed by motor-evoked potential (MEP) in the right m. tibialis anterior before and after PAS. The Physical Activity Questionnaire 50+ and the StepWatchTM captured physical activity levels. Nutritional status was assessed by the Mini Nutritional Assessment. Cognition was assessed by reaction time for a divided attention test and with the Montreal Cognitive Assessment. Neurophysiological activity was assessed by electroencephalography during the divided attention test. MEPs of the highest stimulation intensity resulted significantly different comparing before, 5 min, or 30 min after PAS (p < 0.05). Data-driven automatic hierarchical classification of the individual recruitment curve slopes over the three-time points indicated four different response types, however, response groups did not significantly differ based on physical activity, nutritional status, cognition, or neurophysiological activity. In a second-level analysis, participants having an increased slope showed a significant higher energy expenditure (z = -2.165, p = 0.030, r = 0.36) and revealed a significant higher power activity in the alpha frequency band (z = -2.008, p = 0.046, r = 0.37) at the prefrontal-located EEG electrodes, compared to the participants having a decreased slope. This study hints toward older adults differing in their neuronal excitability which is strongly associated to their short-time synaptic plasticity levels. Furthermore, a physically active lifestyle and higher EEG power in the alpha frequency band seem to be connected to the capacity of generating long-term potentiation-like synaptic plasticity in older adults. Future studies should consider more sensitive assessments and bigger sample sizes to get a broad scope of the older adults’ population.

Cervical Electrical Neuromodulation Effectively Enhances Hand Motor Output in Healthy Subjects by Engaging a Use-Dependent Intervention

“…To detect the possible influence of each intervention and counteract the masking effect of interindividual variability, recruitment curves obtained at 0′ post and 60′ post intervention were normalized to baseline recruitment curves (which were considered as 0% change for all intensities) registered for each session and each subject. As a measure of corticospinal excitability, in addition, slope of non-normalized recruitment curves was calculated through linear regression from 90% to 150% RMT intensities, an interval that fitted linear distribution in all conditions and muscles [ 29 ].…”

Age and APOE genotype affect the relationship between objectively measured physical activity and power in the alpha band, a marker of brain disease.

“…PA has been well established as an important neuroprotective element that has the potential to decrease AD risk and improve AD-related neuropathological burden (Brown et al, 2018;Erickson et al, 2012;Okonkwo et al, 2014). In fact, both greater power in the alpha band and a more active lifestyle have been reported to be associated to an individual's capacity to generate long-term potentiation-like synaptic plasticity (Schättin et al, 2018). PA presents the advantage of being a modi able lifestyle variable.…”

Probing the Brain–Body Connection Using Transcranial Magnetic Stimulation (TMS): Validating a Promising Tool to Provide Biomarkers of Neuroplasticity and Central Nervous System Function

“…Peak-to-peak MEP amplitudes (µV) were averaged across all trials for each TMS intensity (i.e., 105–155% of AMT). The linear relationship between the MEP amplitudes (µV) and TMS intensities (105–155% of AMT) was used to describe the eREC [ 32 , 90 ] ( Figure 2 ). Here, the slope and R 2 of the linear relationship, respectively, quantified the excitatory corticospinal tract recruitment gain and accuracy [ 10 , 19 , 32 ].…”