Does face detection in the superior colliculus rely on input from the primary visual cortex?

In a recent study, Yu and Katz et al. (2024) argue that face-selective visual activity in the superior colliculus (SC) relies on input from the primary visual cortex (V1), based on the loss of visual responses following a temporary lesion to the lateral geniculate nucleus. We argue that alternative explanations deserve consideration. Research on visual recovery after V1 damage (Blindsight) suggests that subcortical pathways, including the SC, can contribute to face detection without V1 involvement. Additionally, the well-documented Sprague Effect, which highlights interhemispheric inhibition of SC activity following ipsilateral V1 damage, may account for the observed suppression of SC visual responses. Further investigation into these mechanisms could help clarify whether SC face detection can operate independently of V1 input.