A novel 3-choice touchscreen task to examine spatial attention and orienting responses in rodents

Abstract

Mammalian orienting behaviour consists of coordinated movements of the eyes, head, pinnae, vibrissae, or body to attend to an external stimulus. The present study aimed to develop a novel operant task using a touch-screen system to measure spatial attention. In this task, rats were trained to nose-poke a light stimulus presented in one of three locations. The stimulus was presented more frequently in the center location to develop spatial attention bias towards the center stimulus. Changes in orienting responses were detected by measuring the animals' response accuracy and latency to stimuli at the lateral locations, following reversible unilateral chemogenetic inactivation of the superior colliculus (SC). Additionally, spontaneous turning and rotation behaviour was measured using an open field test (OFT). Our results show that right SC inactivation significantly increased the whole body turn angle in the OFT, in line with previous literature that indicated an ipsiversive orientating bias and the presence of contralateral neglect following unilateral SC lesions. In the touch screen orienting task, unilateral SC inactivation significantly increased bias towards the ipsilateral side, as measured by response frequency in various experimental conditions, and a very large left-shift of a respective psychometric function. Our results demonstrate that this novel touchscreen task is able to detect changes spatial attention and orienting responses, due to e.g. experimental manipulations or injury, with very high sensitivity while taking advantage of the touch screen technology that allows for high transferability of the task between labs and for open source data sharing through mousebytes.ca.

Significance

Touch-screen rodent testing is a novel translational method of behavioural testing that is more comparable to test batteries used in humans, such as the Cambridge Neuropsychological Test Automated Battery (CANTAB). Its standardized approach in closed boxes allows for better comparability of data between labs and for open source data sharing at the affiliated platform “mousebytes.ca”. The goal of this study was to expand the toolbox for touch-screen boxes to investigate orienting behavior and spatial attention. Unilateral reversible chemogenetic inhibition of the SC revealed an ipsiversive orientating bias and the presence of neglect-like effects for contralateral visual stimuli, demonstrating that this novel task is highly sensitive to detect disruptions of spatial attention associated with psychiatric disorders, brain injury, or experimental manipulations.