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.
