Is This Within Reach? Left but Not Right Brain Damage Affects Affordance Judgment Tendencies

Area of Science:

• Neuroscience
• Cognitive Psychology
• Rehabilitation Medicine

Background:

• Accurate affordance judgments, crucial for adaptive behavior, depend on environmental properties and personal physical capabilities.
• Understanding post-stroke affordance judgment abilities and their neural underpinnings, particularly after left or right hemisphere injuries, remains limited.

Purpose of the Study:

• To investigate how left brain damage (LBD) and right brain damage (RBD) affect reachability judgments in stroke patients.
• To explore the neural mechanisms underlying altered affordance judgments following stroke.

Main Methods:

• Employed a signal detection approach to assess reachability judgments in healthy controls, RBD patients, and LBD patients.
• Analyzed perceptual sensitivity, accuracy, and response criterion across groups.
• Correlated judgment tendencies with lesion locations using lesion analysis.

Main Results:

• No significant differences in perceptual sensitivity or accuracy for reachability judgments were found between healthy controls, RBD, and LBD groups.
• Healthy controls and RBD patients exhibited a negative response criterion, overestimating reachability.
• LBD patients showed a response criterion near zero, indicating no judgment tendency, consistent with prior affordance tasks.

Conclusions:

• Left brain damage, specifically affecting the left insula and temporal-parietal lobes, disrupts judgment tendency for affordances.
• Damage to the left ventro-dorsal stream may impair stable criterion retrieval, increasing reliance on intact bilateral dorsal networks for online body perception.