Normalization of network connectivity in hemispatial neglect recovery.
We recently reported that spatial and nonspatial attention deficits in stroke patients with hemispatial neglect are correlated at 2 weeks postonset with widespread alterations of interhemispheric and intrahemispheric functional connectivity (FC) measured with resting-state functional magnetic resonance imaging across multiple brain networks. The mechanisms underlying neglect recovery are largely unknown. In this study, we test the hypothesis that recovery of hemispatial neglect correlates with a return of network connectivity toward a normal pattern, herein defined as "network normalization."



We measured attention deficits with a neuropsychological battery and FC in a large cohort of stroke patients at, on average, 2 weeks (n = 99), 3 months (n = 77), and 12 months (n = 64) postonset. The relationship between behavioral improvement and changes in FC was analyzed both in terms of a priori regions and networks known to be abnormal subacutely and in a data-driven manner.



Attention deficit recovery was mostly complete by 3 months and was significantly correlated with a normalization of abnormal FC across many networks. Improvement of attention deficits, independent of initial severity, was correlated with improvements of previously depressed interhemispheric FC across attention, sensory, and motor networks, and a restoration of the normal anticorrelation between dorsal attention/motor regions and default-mode/frontoparietal regions, particularly in the damaged hemisphere.



These results demonstrate that abnormal network connectivity in hemispatial neglect is behaviorally relevant. A return toward normal network interactions, and presumably optimal information processing, is therefore a systems-level mechanism that is associated with improvements of attention over time after focal injury. Ann Neurol 2016;80:127-141.
Department of Neurology, Washington University in St. Louis School of Medicine, St. Louis, MO.
Lenny E
LE
Ramsey
Department of Neurology, Washington University in St. Louis School of Medicine, St. Louis, MO.
Joshua S
0000-0002-5752-3641
JS
Siegel
Department of Neuroscience, Imaging, and Clinical Sciences, University of Chieti, Italy.
Antonello
A
Baldassarre
Department of Neurology, Washington University in St. Louis School of Medicine, St. Louis, MO.
Nicholas V
NV
Metcalf
Department of Neurology, Washington University in St. Louis School of Medicine, St. Louis, MO.
Kristina
K
Zinn
Department of Neurology, Washington University in St. Louis School of Medicine, St. Louis, MO.
Gordon L
GL
Shulman
Department of Neurology, Washington University in St. Louis School of Medicine, St. Louis, MO.|Department of Radiology, Washington University in St. Louis School of Medicine, St. Louis, MO.|Department of Anatomy and Neurobiology, Washington University in St. Louis School of Medicine.|Department of Neuroscience, University of Padua, Padua, Italy.
Maurizio
M
Corbetta
D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology*; D009483:Neuropsychological Tests; D010468:Perceptual Disorders / Q000150:complications / Q000503:physiopathology*; D020127:Recovery of Function / Q000502:physiology*; D020521:Stroke / Q000150:complications / Q000503:physiopathology*