The involvement of posterior parietal cortex and frontal eye fields in spatially primed visual search.
BACKGROUND
Right posterior parietal cortex (rPPC) and frontal eye fields (FEF) are known to be involved in processing visuospatial attention. However, the functional involvement of these areas in spatial priming in complex conjunction visual search has yet to be determined.


OBJECTIVE
This study aimed to examine the roles of rPPC and bilateral FEF in conjunction search when spatial ambiguity was reduced by priming the target location.


METHODS
Participants completed a conjunction search task whereby the target location was random or else repeated from the previous trial. Transcranial magnetic stimulation was delivered to each one of the three sites of interest at a time, and task performance was compared with a sham condition.


RESULTS
Spatial priming occurred for all conditions: search times were faster for primed relative to nonprimed trials. When the target appeared at a nonprimed location, stimulation over any of the three sites increased reaction times relative to the sham condition. However, when the target location was repeated, reaction time was only significantly increased by stimulation over the right FEF.


CONCLUSIONS
rPPC and left FEF are only involved when the target location is random, suggesting that these areas are essential for resolving spatial ambiguity to localize targets. Conversely, right FEF contributes equally to visual search regardless of spatial priming. We propose that right FEF has a role in the integration of bottom up saliency and top down expectancy signals and is the node at which rPPC and/or left FEF is either recruited or not.
Cognitive Neuroscience Research Unit (CNRU), Psychology Department, Wolfson Research Institute, University of Durham, Queen's Campus, Stockton-on-Tees, United Kingdom.
Alison R
AR
Lane
Daniel T
DT
Smith
Thomas
T
Schenk
Amanda
A
Ellison
D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000502:physiology*; D011597:Psychomotor Performance; D050781:Transcranial Magnetic Stimulation; D014794:Visual Fields / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult