Perturbation-driven paradoxical facilitation of visuo-spatial function: Revisiting the 'Sprague effect'

Area of Science:

• Neuroscience
• Neurorehabilitation

Background:

• The Sprague Effect describes a paradoxical phenomenon where a subsequent brain lesion reverses deficits caused by an initial lesion.
• Initially observed in cats, it involved visual cortex ablations causing attention deficits, which were reversed by superior colliculus (SC) removal or commissure splitting.

Purpose of the Study:

• To critically reappraise the Sprague Effect in feline and human brains.
• To assess its application in rehabilitating visually guided attention impairments using non-invasive brain stimulation.
• To review theoretical models and their implications for stroke rehabilitation.

Main Methods:

• Critical analysis of studies on the Sprague Effect in cats and humans.
• Assessment of non-invasive therapeutic approaches like transcranial magnetic stimulation (TMS) and transcranial direct-current stimulation (tDCS).
• Review of theoretical models emphasizing inter-hemispheric interactions and lesion inference.

Main Results:

• The Sprague Effect is explained by reduced inter-collicular inhibition and restored cortico-midbrain interactions.
• Non-invasive brain stimulation techniques show potential for rehabilitation.
• Inter-hemispheric rivalry theories offer insights but require further validation for stroke recovery.

Conclusions:

• The Sprague Effect highlights the complex interplay between brain structures and hemispheric balance.
• Further research is needed to overcome challenges in applying the Sprague Effect for effective patient therapies.
• Optimizing rehabilitation strategies for brain-damaged patients remains a key goal.