title: The effects of TMS over dorsolateral prefrontal cortex on trans-saccadic memory of multiple objects.
abstract: Humans typically make several rapid eye movements (saccades) per second. It is thought that visual working memory can retain and spatially integrate three to four objects or features across each saccade but little is known about this neural mechanism. Previously we showed that transcranial magnetic stimulation (TMS) to the posterior parietal cortex and frontal eye fields degrade trans-saccadic memory of multiple object features (Prime, Vesia, & Crawford, 2008, Journal of Neuroscience, 28(27), 6938-6949; Prime, Vesia, & Crawford, 2010, Cerebral Cortex, 20(4), 759-772.). Here, we used a similar protocol to investigate whether dorsolateral prefrontal cortex (DLPFC), an area involved in spatial working memory, is also involved in trans-saccadic memory. Subjects were required to report changes in stimulus orientation with (saccade task) or without (fixation task) an eye movement in the intervening memory interval. We applied single-pulse TMS to left and right DLPFC during the memory delay, timed at three intervals to arrive approximately 100 ms before, 100 ms after, or at saccade onset. In the fixation task, left DLPFC TMS produced inconsistent results, whereas right DLPFC TMS disrupted performance at all three intervals (significantly for presaccadic TMS). In contrast, in the saccade task, TMS consistently facilitated performance (significantly for left DLPFC/perisaccadic TMS and right DLPFC/postsaccadic TMS) suggesting a dis-inhibition of trans-saccadic processing. These results are consistent with a neural circuit of trans-saccadic memory that overlaps and interacts with, but is partially separate from the circuit for visual working memory during sustained fixation.
authors.affiliation: Centre for Vision Research and Canadian Action and Perception Network, York University, Toronto, Canada; Neuroscience Graduate Diploma Program and Departments of Psychology, Biology, and Kinesiology and Health Sciences, York University, Toronto, Canada.
authors.forename: L L
authors.initials: LL
authors.lastname: Tanaka
authors.affiliation: Centre for Vision Research and Canadian Action and Perception Network, York University, Toronto, Canada; School of Psychology, Queen׳s University Belfast, Northern Ireland.
authors.forename: J C
authors.initials: JC
authors.lastname: Dessing
authors.affiliation: Centre for Vision Research and Canadian Action and Perception Network, York University, Toronto, Canada; Neuroscience Graduate Diploma Program and Departments of Psychology, Biology, and Kinesiology and Health Sciences, York University, Toronto, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Malik
authors.affiliation: Department of Psychology, University of Saskatchewan, Canada.
authors.forename: S L
authors.initials: SL
authors.lastname: Prime
authors.affiliation: Centre for Vision Research and Canadian Action and Perception Network, York University, Toronto, Canada; Neuroscience Graduate Diploma Program and Departments of Psychology, Biology, and Kinesiology and Health Sciences, York University, Toronto, Canada. Electronic address: jdc@yorku.ca.
authors.forename: J D
authors.initials: JD
authors.lastname: Crawford
mesh_terms: D000328:Adult; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012438:Saccades / Q000502:physiology*; D013028:Space Perception / Q000502:physiology; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Dorsolateral prefrontal cortex (DLPFC); Saccades; Trans-saccadic perception; Transcranial magnetic stimulation (TMS); Visual working memory