HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 96/5/2377    most recent 01072.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (12) Citing Articles via Google Scholar Google Scholar Articles by Boudreau, C. E. Articles by Maunsell, J. H. R. Search for Related Content PubMed PubMed Citation Articles by Boudreau, C. E. Articles by Maunsell, J. H. R.

Effects of Task Difficulty and Target Likelihood in Area V4 of Macaque Monkeys

¹Howard Hughes Medical Institute and ²Department of Neuroscience, Baylor College of Medicine, Houston, Texas

Submitted 11 October 2005; accepted in final form 12 July 2006

Spatial attention improves performance at attended locations and correspondingly modulates firing rates of cortical neurons. The size of these behavioral and neuronal effects depends on the difficulty of the task performed at the attended location. Psychological theorists have attributed this to a tighter focus of a fixed amount of processing resource at the attended location, but the effects of task difficulty on the distribution of neuronal effects of attention across the visual field have not been fully explored. We trained rhesus monkeys to do a detection task in which difficulty and spatial attention were manipulated independently. Probe stimuli were used to measure behavioral performance in different conditions of attention and difficulty. Animals performed better at attended locations and this advantage increased with difficulty, consistent with data from human psychophysics. Neuronal modulation by spatial attention was larger with greater difficulty. In two animals, increasing difficulty caused a modest increase in neuronal responses to visual stimuli regardless of the locus of spatial attention. In a third animal, which was previously trained to ignore multiple distracting stimuli, increasing task difficulty increased responses at the focus of attention and suppressed responses away from the focus of attention. The results show that difficulty can modulate effects of spatial attention in V4; it can alter the distribution of sensory responses across the visual scene in ways that may depend on the subject's behavioral strategy.

This article has been cited by other articles:

				G. M. Ghose Attentional Modulation of Visual Responses by Flexible Input Gain J Neurophysiol, April 1, 2009; 101(4): 2089 - 2106. [Abstract] [Full Text] [PDF]

				P. Yin, M. Mishkin, M. Sutter, and J. B. Fritz Early Stages of Melody Processing: Stimulus-Sequence and Task-Dependent Neuronal Activity in Monkey Auditory Cortical Fields A1 and R J Neurophysiol, December 1, 2008; 100(6): 3009 - 3029. [Abstract] [Full Text] [PDF]

				G. M. Ghose and J. H. R. Maunsell Spatial Summation Can Explain the Attentional Modulation of Neuronal Responses to Multiple Stimuli in Area V4 J. Neurosci., May 7, 2008; 28(19): 5115 - 5126. [Abstract] [Full Text] [PDF]

				D. Yoshor, G. M. Ghose, W. H. Bosking, P. Sun, and J. H. R. Maunsell Spatial Attention Does Not Strongly Modulate Neuronal Responses in Early Human Visual Cortex J. Neurosci., November 28, 2007; 27(48): 13205 - 13209. [Abstract] [Full Text] [PDF]