Evidence indicates attention can alter afferent inhibition, a Transcranial Magnetic Stimulation (TMS) evoked measure of cortical inhibition following somatosensory input. When peripheral nerve stimulation is delivered prior to TMS, a phenomenon known as afferent inhibition occurs. The latency between the peripheral nerve stimulation dictates the subtype of afferent inhibition evoked, either short latency afferent inhibition (SAI) or long latency afferent inhibition (LAI). While afferent inhibition is emerging as a valuable tool for clinical assessment of sensorimotor function, the reliability of the measure remains relatively low. Therefore, to improve the translation of afferent inhibition within and beyond the research lab, the reliability of the measure must be improved. Previous literature suggests that the focus of attention can modify the magnitude of afferent inhibition. As such, controlling the focus of attention may be one method to improve the reliability of afferent inhibition. In the present study, the magnitude and reliability of SAI and LAI was assessed under four conditions with varying attentional demands focused on the somatosensory input that evokes SAI and LAI circuits. Thirty individuals participated in four conditions; three conditions were identical in their physical parameters and varied only in the focus of directed attention (visual attend, tactile attend, non- directed attend) and one condition consisted of no external physical parameters (no stimulation). Reliability was measured by repeating conditions at three time points to assess intrasession and intersession reliability. Results indicate that the magnitude of SAI and LAI were not modulated by attention. However, the reliability of SAI demonstrated increased intrasession and intersession reliability compared to the no stimulation condition. The reliability of LAI was unaffected by the attention conditions. This research demonstrates the impact of attention/arousal on the reliability of afferent inhibition and has identified new parameters to inform the design of TMS research to improve reliability.
BACKGROUND Mild cognitive impairment (MCI) is a syndrome before more severe impairment characterized by dementia. MCI affects an estimated 15% to 20% of people over age 65. Non-pharmacological interventions including exercise are recommended as part of overall MCI management based on the positive effects of exercise on cognitive performance. Interval training involves brief intermittent bouts of exercise interspersed with short recovery periods. This type of exercise promotes cognitive improvement and can be performed in individuals with MCI. Synaptic plasticity can be assessed in-vivo by the neurophysiological response to repetitive transcranial magnetic stimulation. It is unknown whether interval training causes changes in synaptic plasticity in individuals living with MCI. OBJECTIVE This research will determine whether interval training performed using a cycle ergometer enhances synaptic plasticity in older individuals with MCI. The two aims are: (1) to quantify synaptic plasticity after interval training performed at a self-selected intensity in aging and in individuals with MCI, and (2) to determine whether changes in synaptic plasticity correlate with changes in serum brain-derived neurotrophic factor, osteocalcin, and cognition. METHODS Thirty-six individuals will be recruited for assignment to one of three equally sized groups: exercise in MCI, no exercise in MCI and exercise non-MCI. The Exercise MCI group and the exercise non-MCI will perform thrice weekly exercise sessions for four weeks. Synaptic plasticity will be measured before the exercise intervention and following the four-week intervention. At these time points, synaptic plasticity will be measured as the response to single pulse TMS. before and after an rTMS protocol used to induce synaptic plasticity. RESULTS The study began as of March 2023. CONCLUSIONS The proposed research is the first to assess whether synaptic plasticity is enhanced after exercise training in individuals with MCI. If exercise does, indeed, modify synaptic plasticity, this will create a new avenue by which we can study and manipulate the neural plasticity in these individuals. CLINICALTRIAL clinicaltrials.gov Trial number: NCT05663918
Sensorimotor integration refers to the process of combining incoming sensory information with outgoing motor commands to control movement. Short-latency afferent inhibition (SAI), and long-latency afferent inhibition (LAI) are neurophysiological measures of sensorimotor integration collected using transcranial magnetic stimulation. No studies to date have investigated the influence of tactile discrimination training on these measures. This study aimed to determine whether SAI and LAI are modulated following training on a customdesigned tactile discrimination maze task. Participants performed a 'high difficulty' and 'low difficulty' maze training condition on separate visits. On an additional visit, no maze training was performed to serve as a control condition. Despite evidence of performance improvements during training, there were no significant changes in SAI or LAI following training in either condition. The total number of errors during maze training was significantly greater in the high-difficulty condition compared with the low-difficulty condition. These findings suggest that sensorimotor maze training for 30 min is insufficient to modify the magnitude of
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.