Effects of allocation of visuo-spatial attention to visual stimuli triggering unilateral arm abduction on anticipatory postural control

OBJECTIVE: We investigated the effects of allocation of visuo-spatial attention to visual stimuli triggering arm movement on anticipatory postural control. METHODS: Fourteen healthy right-handed subjects participated in the study. Visual stimuli were randomly presented to the left or right visual field on a screen. An attention-directing cue or a non-directional cue was presented at 1000ms before visual stimulus onset. Subjects focused or divided visuo-spatial attention (focused- and divided-attention conditions, respectively) based on types of cues, and abducted the left or right arm rapidly in response to target stimuli (with 30% probability of visual stimuli) according to the side of presentation. Peak-to-peak amplitude of P1 and N1 components of event-related potentials (P1-N1 amplitude) elicited by visual stimuli and activation timing of postural muscles with respect to the middle deltoid were measured. RESULTS: Compared with divided-attention condition, in focused-attention condition P1-N1 amplitude at occipital electrodes was enhanced and activation of the left hip abductors during right arm abduction was hastened. A significant correlation was observed between the attention-related changes in these two measurements. CONCLUSIONS: Anticipatory postural control during right arm abduction was influenced by attention-related modulation of sensory-perceptual processing. SIGNIFICANCE: These findings are important for understanding of the effects of visuo-spatial attention on anticipatory postural control.