Exploring the effects of rhythmic afferent alpha and gamma range electrical stimulation on processing mechanisms in a tone discrimination dual-task paradigm

Neural oscillations are the changes in the action potentials and the local field potentials (LFPs) of the central nervous system (CNS). Synchrony is when cell populations in different parts of the brain are activated together to achieve a task. The synchrony of brain oscillatory activity could modulate information processing. Synchrony of different oscillatory frequencies can have effects on cognition, motor skills and behaviour. Faster reaction times are correlated with neural oscillations in the alpha (8-12 Hz) or gamma (30-80 Hz) ranges. Rhythmic afferent electrical stimulation in these ranges could influence neural oscillators for speed of processing or task organization. Our aim is to identify how rhythmic electrical stimulation influences performance in a dual-task paradigm using postural and reaction time tasks. Twelve subjects had a transcutaneous nerve stimulation (TENS) protocol applied to their median nerve, in 5 frequency conditions while discerning between two auditory stimuli and maintaining stable balance. Center of pressure (CoP) data were collected under 3 postural conditions. Reaction times, response correctness, CoP excursion and range were measured. There was a main effect of TENS frequency on reaction time; reaction times were longer during a 10 Hz TENS condition. There was a main effect of postural condition; the eyes closed, sway referenced condition had larger excursion and range. Alpha-range TENS lengthened reaction times and had an effect on postural dual-task performance. Further research could identify how afferent rhythmic stimulation affects processing mechanisms