Following the gold trail: Reward influences on spatial exploration in neglect

Abstract

Spatial attention is guided by the perceived salience and relevance of objects in the environment, a process considered to depend on a broad parieto-frontal cortical network. Signals arising from the limbic and nigrostriatal pathways conveying affective and motivational cues are also known to modulate visual selection, but the nature of this contribution and its relation to spatial attention remain unclear. We investigated the role of reward information in 15 patients with left hemispatial neglect and 15 control subjects playing multiple rounds of a virtual foraging game. Participants' exploration tracked dynamically adjusted underlying reward distributions, largely unbeknownst to them. Both control and neglect participants showed typical exploration/exploitation balance dependent on abundance or scarcity of rewards. De-reinforcing previously favored, mostly right, regions of space attenuated left space under-exploration in patients. Multiple regression analysis indicates that such reward-based training may benefit mostly patients early after lesion onset, with mild neglect and small lesions sparing subcortical regions. Our findings support the view that spatial exploration recruits heavily right hemispheric visuospatial attentional mechanisms as well as reward signals processed by basal ganglia and prefrontal cortical circuits, which serve to learn about the motivational relevance of environmental stimuli and help prioritize attention and motor response selection.

The Effects of Continuous vs. Intermittent Prism Adaptation Protocols for Treating Visuospatial Neglect: A Randomized Controlled Trial

“…In our view, this is an important difference from the designs of Vilimovsky et al or Ten Brink et al, and we believe that this kind of adaptation of PA is essential for treating especially severely impaired patients with neglect due to their additional emotional and motivational impairments. This claim is supported by previous studies on reward-based learning following right hemisphere damage and neglect, showing that reward-induced modulations of space representation are preserved in neglect (61), reward positively influences spatial exploration (62), motivational valence modulates attentional impairments (63), and rewardbased training may benefit most patients early after lesion onset (62).…”

“…Fourth, although we provide global information on lesion locations, exact information is lacking. From previous studies it is known that lesion location can influence PA treatment response of neglect patients (34,62,65). However, most of the patients (16 out of 24) received both phases of the cross-over and, hence, both interventions, minimizing possible effects solely due to specific lesion characteristics.…”

Co-administration of prism adaptation and methylphenidate needs striatal integrity to alleviate spatial neglect

“…Lee et Shomstein 2013; Jeongmi Lee et Shomstein 2014). Reinforcement learning could influence the bottom-up influences of stimulus features on attentional allocation during spatial decision making (Neppi-Mòdona et al 2020).…”