Modulatory effect of executive control through the presence of priority-cue and retro-cue on external-to-internal attention and maintenance of internal representation: a behavioural and electrophysiological study

Abstract

Background Emerging evidence has shown that the presence of visual cues under executive control could influence the attentional orientation to stimuli and representation. However, this modulatory effect of top-down visual cues has not been investigated in external, internal, or external-to-internal orientation in motor context. Concurrent motor imagery and action observation (AOMI) has been shown to heighten the cortical activations in the Action Observation Network (AON) and imagery-related network. AOMI involves attentional orientation from external images of action to internally generated kinesthetic images. It is speculated that the rapid shifting between external visual image and internal kinesthetic representation and the transition from visual to kinesthetic representation demand a higher level of top-down executive control, and it is suggested that the involvement of top-down visual cues might enhance the effect of AOMI, which in turn improves the motor performance in terms of precision. While visual cues may aid in the selection of relevant information and the suppression of irrelevant representations, their presence may also consume executive function resources. However, the related processes have not been well addressed. Objectives There were one pilot study and two main studies in the study. In the pilot study, it was aimed to examine if providing external-to-internal attention orientation training before AOMI would affect executive control on attention shifting. Study One aimed (1) to examine if the modulatory effect of executive control on external-to-internal attention orientation through the presence of priority-cue in visual imagery and subsequent maintenance of visual representation in terms of behavioral measures and cortical oscillations; (2) to examine if the modulatory effect of executive control on internal maintenance through the presence of retro-cue and subsequent inspection of visuomotor representation in terms of measures and cortical oscillations. Study Two aimed to examine if the modulatory effect of executive control through the presence of priority-cue and retro-cue on inspection and maintenance of kinesthetic representation in AOMI in terms of motor precision and cortical oscillations. Methods Twelve healthy volunteers (mean age = 25±3.4) were recruited to participate in AOMI training in the pilot study. All the volunteers were allocated to either of the two training groups: (1) action observation and passive movement (AOPM) training (experimental group) or (2) action observation (AO) training. Each participant was required to complete 3 outcome tests, including the proprioceptive test, the Purdue Pegboard test, and the Stroop test, before and after the AOMI training. Healthy adults (Study One: N = 20; mean age = 25.3±3.0; Study Two: N = 25; mean age = 26.1±4.4) were recruited to participate in delayed recognition tasks in Study One and cognitive-motor tasks in Study Two. The delayed recognition task in Study One consisted of 4 conditions, including (1) delayed recognition (control) task, (2) delayed recognition task with priority-cue, (3) delayed recognition task with retro-cue, and (4) delayed recognition task with priority-cue and retro-cue conditions. Reaction time, accuracy, and electroencephalogram data were recorded during the delayed recognition tasks in Study One. To accomplish the objectives, repeated measures ANOVA was used to examine: 1) the behavioural performance of the delayed recognition tasks; 2) the mean theta-band power in the presence of retro-cue; and 3) the mean alpha-band power during the maintenance phase. Study Two consisted of two conditions, i.e. (1) AOMI (control) condition, and (2) AOMI with priority-cue and retro-cue condition. Joint precision and electroencephalogram data were recorded during the cognitive-motor tasks in Study Two. To achieve the objectives, repeated measure ANOVA was used to examine 1) the joint precision of cognitive-motor tasks, 2) the mean theta-band power in the presence of retro-cue, and 3) the mean alpha-band power during the maintenance phase. Results In Study One, shorter reaction time and higher accuracy were found in the retro-cue condition and priority-cue and retro-cue condition. Higher frontal theta-band power was found in the retro-cue, priority-cue and retro-cue condition during retro-cue parietal alpha-band power was found in the retro-cue, priority-cue and retro-cue condition during maintenance. In Study Two, enhancement in elbow joint precision was found in priority-cue and retro-cue condition. Higher theta-band power was found in priority-cue and retro-cue condition over left frontal cortical sites during retro-cue. Lower alpha-band power was found in priority-cue and retro-cue condition over right parietal cortical sites during maintenance. Conclusion The findings of this study shed light on how the higher centre of executive control on the attention and imagery-related systems and the presence of priority-cue and retro-cue on modulating attention Furthermore, the results of this study provided an insight on using priority-cue and retro-cue in cognitive training strategies to incorporate visual cues to enhance the attention orientation in individuals with attentional control deficits, e.g., elderly with mild cognitive impairments. The presence of both cues yielded the greatest beneficial effect on behavioural performance and showed a reduction in the alpha-band oscillations. It can pave the way to constructing an efficient programme to learn or relearn motor movement.