Abstract
Allocation and orienting of visuospatial attention are modulated by release of acetylcholine in cortex. In this study we measured the effects of pharmacological enhancement of the cholinergic system on voluntary and involuntary attention in healthy human participants.
Subjects performed a visual discrimination task in which they reported the tilt of a grating that appeared in one of four spatial locations in the visual display, arranged around the fixation point. An anti-cueing paradigm was used to manipulate attention. Each trial began with presentation of a salient cue in one of the four locations. For 20% of the trials, the target then appeared in the cued location, and for the remaining 80% of trials, the target appeared in the location diametrically opposite the cue.
Trials were blocked based on stimulus onset asynchrony (SOA) between cue and target presentation: long (600 msec) or short (40 msec). For long SOA trials, allocation of voluntary attention to the expected target location resulted in shorter response times (RTs) when the target appeared in the location opposite the cue. However, when the SOA was short, the involuntary capture of attention resulted in the opposite pattern: In these blocks, RTs were significantly shorter when the target appeared in the same location as the cue.
Participants performed the task in a double-blind, placebo-controlled, crossover design. The cholinesterase inhibitor donepezil (trade name: Aricept) was administered to increase synaptic acetylcholine levels. This enhanced the effect of cueing (difference in RT for valid and invalid trials) for long SOA but not short SOA blocks.
This result demonstrates cholinergic modulation of voluntary but not involuntary visuospatial attention.
We would like to thank Jon Kelvey for his help in collecting and analyzing the data. This work was supported by NIH grant R21-EY017926 and the Hellman Family Faculty Fund.