Dual cognitive task affects reaching and grasping behavior in subjects with macular disorders

Area of Science:

• Neuroscience
• Ophthalmology
• Human Movement Science

Background:

• Individuals with macular disorders often require more time for reaching and grasping tasks.
• Everyday activities frequently involve combining reaching/grasping with cognitive tasks.
• The automatic parieto-premotor pathway is traditionally thought to control visually guided actions.

Purpose of the Study:

• To investigate the impact of a simultaneous cognitive task (counting) on reaching and grasping in visually impaired (VI) subjects.
• To test the hypothesis that cognitive load minimally affects visually guided movements due to their automatic nature.

Main Methods:

• 14 subjects with VI and 14 controls performed reaching and grasping tasks under three counting conditions (easy, difficult, no count).
• A 3D motion analysis system captured hand and finger movements.
• Performance metrics included onset time, grip changes, and velocity.

Main Results:

• Significant differences were observed between VI subjects and controls across various movement indices.
• Dual-tasking significantly affected movement onset time and online corrections in both groups.
• Interaction effects indicated that the counting task influenced both movement planning and real-time adjustments.

Conclusions:

• Cognitive tasks requiring attention and working memory impact movement onset time in both VI and control groups.
• In VI subjects, dual-tasking specifically impaired online corrections during reaching and grasping.
• Findings suggest that visually guided movements, particularly in VI individuals, involve more than just automatic processes.