The Effects of Single Exercise Sessions on Cognitive Flexibility and Brain Functional Connectivity in Older Adults With Cognitive Impairment

Cognitive flexibility was assessed using the More-odd-shifting task paradigm, which was designed with E-prime software. The testing environment was quiet, well ventilated and moderately lit. The stimuli used in the More-odd-shifting task were red or green Arabic numerals from 1 to 9, excluding 5. Participants were required to make key-press responses according to the task instructions when the stimuli appeared. The More-odd-shifting task consisted of three conditions: Condition 1, judgment of numerical magnitude; Condition 2, judgment of parity; and Condition 3, mixed judgment of numerical magnitude and parity.

Brain functional connectivity analysis was performed using MATLAB scripts, and graph-theoretical analysis was carried out using the BrainNet Viewer toolbox. Phase locking value (PLV) was used, and brain functional connectivity was evaluated from two dimensions: connectivity strength and density. In this study, PLV was calculated for the δ, θ, α1, α2, β1 and β2 bands of resting-state EEG using MATLAB, and the formula is shown in Equation (1). Here, i is the imaginary unit, Δt is the time interval between two consecutive samples, and N is the total number of samples. PLV is an index used to quantify phase synchrony in EEG signals and assesses whether two signals maintain a relatively stable phase relationship over time. Its value ranges from 0 to 1, where 1 indicates complete synchrony and 0 indicates no synchrony. PLV is commonly used to investigate phase synchrony between different brain regions, particularly functional connectivity related to neural oscillations.