Induced sensorimotor cortex plasticity remediates chronic treatment-resistant visual neglect.

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Cognitive Psychology

Background:

• Right brain injury frequently causes visual neglect, characterized by a loss of awareness in left space.
• Prism adaptation therapy, involving optical shifts and motor recalibration, offers transient improvement in left neglect.
• The transient nature of prism adaptation therapy necessitates strategies for enhancing long-term consolidation.

Purpose of the Study:

• To investigate whether tonic disinhibition of the left motor cortex during prism adaptation enhances the consolidation of sensorimotor and cognitive after-effects.
• To determine if this combined stimulation/adaptation approach can lead to persistent improvements in chronic visual neglect.

Main Methods:

• Three longitudinal patient case series were conducted.
• Participants underwent a 20-minute combined session of tonic disinhibition of the left motor cortex and prism adaptation.
• The duration and persistence of cognitive after-effects (neglect improvement) were monitored throughout follow-up periods (18-46 days).

Main Results:

• The combined stimulation and adaptation protocol resulted in persistent cognitive after-effects, with neglect improvement lasting throughout the follow-up period.
• Adaptation alone, without the concurrent stimulation, was ineffective in producing lasting benefits.
• The stimulation effectively reversed treatment resistance in chronic visual neglect.

Conclusions:

• Tonic excitation of left sensorimotor circuits during prism adaptation can durably improve resistant visual attention deficits.
• This approach unmasks latent plastic potential, challenging the consensus of suppressing the over-excited left hemisphere in neglect.
• The findings suggest a novel therapeutic strategy for enhancing long-term recovery from visual neglect after brain injury.