Neurobiology of Unilateral Spatial Neglect

Abstract

Hemispatial neglect is a common and disabling consequence of stroke. Earlier studies aimed to identify a single area of the brain where damage caused neglect and sought a single disrupted process that could account for the symptoms. Recent studies have shifted toward identifying component processes and representations underlying spatial attention required for various tasks and identifying areas of the brain responsible for each component that together constitute the network of regions responsible for neglect. This review focuses on recent insights into the mechanisms of neglect, regions of neural dysfunction that cause disruption of particular components or forms of neglect, and potential means of ameliorating neglect. Converging evidence supporting these insights comes from new imaging modalities in acute stroke, functional imaging, transcranial magnetic stimulation, electrophysiological studies in humans, and single-cell recording studies in nonhuman primates.

Synchronization of fronto-parietal beta and theta networks as a signature of visual awareness in neglect

“…It is characterized by both a rightward bias in spatial sensory-motor processing and non-lateralized deficits of arousal, attentional capacity, and working memory Hillis, 2006;Bartolomeo et al, 2012). Traditionally, neglect has been explained in terms of localized damage of specific right-hemisphere brain structures including the inferior parietal lobe (Vallar and Perani, 1986;Mort et al, 2003), superior temporal gyrus (Karnath et al, 2004), and inferior frontal cortex (Husain and Kennard, 1996).…”

Heminegligencia visuo-espacial: aspectos clínicos, teóricos y tratamiento [Visuospatial neglect: clinical, theoretical and treatment aspects]

“…Hillis (2006) atribuye la existencia de esta disparidad hemisférica a la ubicación, en la mayoría de personas diestras, del procesamiento lingüístico en el hemisferio izquierdo; mientras que el hemisferio derecho es el principal responsable de las funciones visuo-espaciales no verbales. Esta diferencia hemisférica no se detecta en primates u otros animales.…”

“…También se ha asociado a lesiones subcorticales del hemisferio derecho: núcleo pulvinar del tálamo, caudado y putamen (Karnath et al, 2005). Hillis (2006) propone que la forma más grave y frecuente de HVE se observa después de lesiones localizadas en el surco intra-parietal y la corteza temporo-parietal del hemisferio derecho.…”

Alzheimer's Factors in Ischemic Brain Injury

“…Stroke is the third most common cause of death and the second most common cause of dementia in industrialized societies with a mortality rate of circa 30% and an incidence of about 250-400 in 100,000. Stroke affects circa 700,000 people each year in the US alone, and about 50% of these individuals will experience lasting functional dysfunctions including sensory problems and cognitive deficits (Hillis 2006). It is estimated that ischemic stroke is responsible for approximately half of all patients hospitalized for acute neurological disorders.…”