Ready, set, point: the effects of alertness on prism adaptation in healthy adults.

Prism adaptation (PA) is a promising rehabilitation technique for visuo-spatial neglect, an attention disorder that is characterized by spatial attention deficits (i.e., deficits in orienting). PA involves visuo-motor adaptation to rightward shifting prism goggles. Following goggle removal, this adaptation results in leftward shifts in visuo-motor aiming and amelioration of spatial neglect. Even though some studies clearly support the beneficial effects of PA for spatial neglect, not all studies find benefits, thus it remains unclear how PA effects could be improved. Taking advantage of the known interactions between orienting and alerting reported in the attention literature (i.e., alerting enhances orienting function; e.g., Ishigami and Klein in J Individ Differ 30:220-237. doi: 10.1027/1614-0001.30.4.220 , 2009, in J Neurosci Methods 190:117-28. doi: 10.1016/j.jneumeth.2010.04.019 , 2010; Robertson et al. in Nature 395:169-72. doi: 10.1038/25993 , 1998), we examined the effects of alerting tones on PA with healthy young and older adults. We found that the effects of alerting on PA with young adults were negative, while there was a positive effect with older adults, specifically on a visuo-motor outcome task. Thus, enhancement of PA effects by alerting may be age specific and task specific. Therefore, we can conclude that while the impact of alerting tones is not always positive, further research in patients with neglect may be warranted.