Establishment of an aged mouse model of unilateral spatial neglect and the impact of aging on symptom severity

This study focused on unilateral spatial neglect (USN), a disorder of attention on the contralateral side caused by damage to the cerebral hemispheres. Existing evidence-based rehabilitation for USN is insufficient, prompting the need for an animal model to develop effective treatments. The study aims to establish an aged mouse model of USN targeting the medial agranular cortex, analogous to the human frontal eye field. Focal infarcts were induced in aged mice using photothrombosis, and USN was assessed in an 8-arm radial maze. Mice were given 11 minutes to freely explore the 8-arm radial maze, and the rate at which they chose the left arm from the mouse's perspective (left-side selection rate = the number of left-side arm entries/the total number of arm entries) was calculated. Results indicated a reduction in left selectivity after infarction, signifying USN symptoms in the aged mice. Moreover, symptoms in the aged USN model mice were more severe than in the younger USN model. This study revealed a simple and objective evaluation of USN symptoms in aged mice, which are more pronounced than those in younger mice. This model may contribute to the development of effective therapies for human USN.