The development of treatments for freezing of gait (FOG) in Parkinson's disease (PD) requires experimental study set-ups in which FOG is likely to occur, and is amenable to therapeutic interventions. We explore whether the 'Auditory Stroop Task' (AST) can be used to increase cognitive load (and thereby elicit FOG), simultaneously with visual cues (as a therapeutic intervention for FOG). We additionally examined how these two contrasting effects might interact in affecting gait and FOG parameters. We investigated whether: (1) the 'Auditory Stroop Task' (AST) influences gait in healthy elderly and persons with PD who experience FOG, and increases the frequency of FOG events among PD patients; (2) the AST and visual cues interact; and (3) different versions of the AST exert different cognitive loads. In 'Experiment 1', 19 healthy elderly subjects performed a walking task while performing a high and low load version of the AST. Walking with a random numbers task, and walking without cognitive load served as control conditions. In 'Experiment 2', 20 PD patients with FOG and 18 healthy controls performed a walking task with the AST, and no additional cognitive load as control condition. Both experiments were performed with and without visual cues. Velocity, cadence, stride length, and stride time were measured in all subjects. FOG severity was measured in patients. Compared to the control conditions, the AST negatively affected all gait parameters in both patients and controls. The AST did not increase the occurrence of FOG in patients. Visual cues reduced the decline in stride length induced by cognitive load in both groups. Both versions of the AST exerted similar effects on gait parameters in controls. The AST is well-suited to simulate the effects of cognitive load on gait parameters, but not FOG severity, in gait experiments in persons with PD and FOG.

Current developments towards multipin, dry electrodes in electroencephalography (EEG) are promising for applications in non-laboratory environments. Dry electrodes do not require the application of conductive gel, which mostly confines the use of gel EEG systems to the laboratory environment. The aim of this study is to validate soft, multipin, dry EEG electrodes by comparing their performance to conventional gel EEG electrodes. Fifteen healthy volunteers performed three tasks, with a 32-channel gel EEG system and a 32-channel dry EEG system: the 40 Hz Auditory Steady-State Response (ASSR), the checkerboard paradigm, and an eyes open/closed task. Within-subject analyses were performed to compare the signal quality in the time, frequency, and spatial domains. The results showed strong similarities between the two systems in the time and frequency domains, with strong correlations of the visual (ρ = 0.89) and auditory evoked potential (ρ = 0.81), and moderate to strong correlations for the alpha band during eye closure (ρ = 0.81–0.86) and the 40 Hz-ASSR power (ρ = 0.66–0.72), respectively. However, delta and theta band power was significantly increased, and the signal-to-noise ratio was significantly decreased for the dry EEG system. Topographical distributions were comparable for both systems. Moreover, the application time of the dry EEG system was significantly shorter (8 min). It can be concluded that the soft, multipin dry EEG system can be used in brain activity research with similar accuracy as conventional gel electrodes.

Sensorimotor synchronization (SMS) involves the coordination of movements with rhythmic sensory cues. While cue characteristics influence SMS behaviour and neural pathways, their impact on cortical activity beyond motor areas is less understood. This exploratory EEG study examined how various cue characteristics, including cue frequency, modality and rhythmicity, influence behaviour and movement‐related cortical activity in (non‐)motor areas during SMS. Seventeen healthy participants performed finger tapping with cues varying in frequency (slow: 1 Hz, fast: 3.2 Hz), modality (visual, auditory) and rhythmicity (isorhythmic, polyrhythmic). SMS behaviour and movement‐related beta power were evaluated. Key findings include the following: (1) Increasing cue frequency, and therefore movement speed, reduced tap accuracy, especially with visual cues. Slow cues induced strong beta suppression followed by beta rebound after the tap in the contralateral sensorimotor cortex, while fast cues induced a weaker but sustained beta suppression. (2) Auditory cues enabled more accurate tap behaviour and induced stronger beta suppression in the contralateral premotor cortex compared to visual cues. (3) Polyrhythmic auditory cues delayed taps compared to isorhythmic cues, although tap accuracy was similar. Isorhythmic cues enhanced frontoparietal beta power, whereas polyrhythmic cues showed widespread right‐hemispheric beta suppression. Findings suggest discrete and continuous movement processing with slow and fast cues, respectively. Auditory cues offer more sensory guidance, especially at higher frequencies. Endogenous, top‐down control with isorhythmic cues may switch towards stimulus‐driven, bottom‐up control with auditory polyrhythmic cues. Overall, our findings highlight how cue characteristics shape motor behaviour and neural processes, suggesting distinct movement control strategies depending on frequency, modality and rhythmicity.