Representation and disconnection in imaginal neglect.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neurology

Background:

• Neglect is a deficit in detecting, orienting to, or responding to stimuli from a specific spatial region, typically the left side.
• Previous research suggests visual input can influence neglect symptoms, but its effect on representational (imaginal) neglect is debated.
• Theories propose imaginal neglect involves failure to generate mental images or deficits in attention orienting (bottom-up and top-down).

Observation:

• A patient with right hemisphere damage (R.D.) explored a map visually and imaginally.
• R.D. showed a bias towards the right side in both visual and imaginal exploration, but not in a propositional task.
• This rightward bias was consistent regardless of mental rotation or response type (verbal or manual).

Findings:

• Representational neglect in R.D. was robust and not influenced by visual input or task demands.
• Damage to right hemisphere white matter tracts and the splenium of the corpus callosum correlated with imaginal neglect.
• A second patient with spared callosal connections did not exhibit imaginal neglect.

Implications:

• Imaginal neglect may stem from fronto-parietal dysfunction and disrupted interhemispheric communication.
• Findings suggest distinct neural mechanisms for visual and imaginal neglect.
• Understanding these mechanisms is crucial for diagnosing and treating spatial attention disorders.