2021/10/28 | Research | Rehabilitation & Neural Engineering

Fathoming Visual Neglect

The neuropsychological attention disorder Visual Neglect can occur after brain lesions. However, it is difficult to establish a precise cause-effect correlation between the injured brain regions and the occurrence of this disorder. In a research letter in JAMA Neurology researchers from the ARTORG Center, Inselspital and Luzerner Kantonsspital now describe a patient case that could shed more light on the possible origins of the hemiplegic perception deficit.

T1-Weighted Contrast Magnetic Resonance Imaging (MRI), Showing an Abscess Confined to the Right Superior Colliculus (doi:10.1001/jamaneurol.2021.3863)

In humans, the midbrain superior colliculus (SC) is an essential part of a large fronto-subcortical attentional network. Case studies show that visuospatial inattention, often referred to as visual neglect, can occur after extensive brain lesions that also affect the SC. Thomas Nyffeler, ARTORG Gerontechnology and Rehabilitation group, Department of Neurology, Inselspital, Bern University Hospital and Neurocenter, Luzerner Kantonsspital, and colleagues have now described in JAMA Neurology, how a small, isolated lesion confined to the SC caused contralesional visual neglect in a patient.

The patient underwent a series of free visual exploration tests three and nine months after diagnosis and medical treatment. Results showed a clear connection between the lesion location in the right SC and a leftward neglect, manifested in mean gaze position and significantly fewer and shorter fixations than a healthy comparison group of 15 age- and sex-matched healthy controls.

This rare case provides direct evidence for the role of the SC in the human brain for directing visual attention and the eyes toward the contralateral hemispace. This supports the assumption that the SC is a crucial neural substrate of visual attention control itself.