Spatial attention affects brain activity in human primary visual cortex

Abstract

Biochemistry. In the article "Clonal selection and in vivo quantitation of protein interactions with protein-fragment complementation assays" by Ingrid Remy and Stephen W. Michnick, which appeared in number 10, May 11, 1999, of Proc. Natl. Acad. Sci. USA (96, 5394-5399) Immunology. In the article entitled "Murine natural killer cells contribute to the granulomatous reaction caused by mycobacterial cell walls" by I. Apostolou, Y. Takahama, C. Belmant, T. Kawano, M. Huerre, G. Marchal, J. Cui, M. Taniguchi, H. Nakauchi, J.-J. Fournié, P. Kourilsky, and G. Gachelin, which appeared in number 9, April 27, 1999 of Proc. Natl. Acad. Sci. USA (96,(5141)(5142)(5143)(5144)(5145)(5146), the authors request that the following correction be noted: the title should be "Murine natural killer T (NKT) cells contribute to the granulomatous reaction caused by mycobacterial cell walls." Neurobiology. In the articles "An empirical basis for Mach bands" by R. Beau Lotto, S. Mark Williams, and Dale Purves, which appeared in number 9, April 27, 1999, of Proc. Natl. Acad. Sci. USA (96,(5239)(5240)(5241)(5242)(5243)(5244), and "Mach bands as empirically derived associations" by R. Beau Lotto, S. Mark Williams, and Dale Purves, which appeared in number 9, April 27, 1999, of Proc. Natl. Acad. Sci. USA (96,(5245)(5246)(5247)(5248)(5249)(5250), the following correction should be noted. The reproduction of some of the figures in these papers was unsatisfactory due to the presence of moiré patterns and other deficiencies in the published versions. Given the difficulty in faithfully reproducing gradients in print, readers may wish to view the electronic versions of the figures at purveslab.neuro.duke.edu.Psychology. In the article "Spatial attention affects brain activity in human primary visual cortex" by Sunil P. Gandhi, David J. Heeger, and Geoffrey M. Boynton, which appeared in number 6, March 16, 1999, of Proc. Natl. Acad. Sci. USA (96, 3314-3319), due to an error in the PNAS office, a sentence was omitted. The sentence is shown in bold type in context in the complete paragraph below.On the other hand, it is certainly possible that the V1 modulation we observed might have nothing to do with the improved behavioral performance. For example, the memory load differs between the tasks in the main experiment and the spatial uncertainty experiment. In the spatial uncertainty experiment, subjects must remember two speeds instead of one during the 250 msec inter-stimulus interval. This difference in memory load might be causing the improved behavioral performance. Or the improved performance may result from subjects simply ignoring information from the uncued side, and thus may not be causally related to V1 modulation. It is difficult, however, to imagine that such a significant modulation of activity in visual cortex would fail to have consequences on perceptual thresholds. 7610Corrections Proc. Natl. Acad. Sci. USA 96 (1999) Communicated by Jacob Nachmias, University of Pennsylvania, Philadelphia, PA, December 21, 1998 (received for review...

The neural basis of the blood–oxygen–level–dependent functional magnetic resonance imaging signal

“…BOLD fMRI in such cases will reveal significant activation and will appear to provide results that do not match those of neurophysiology. In this manner a number of experiments in monkeys appear to be inconsistent with fMRI experiments employing the same tasks or stimulation conditions (Tong et al 1998;Gandhi et al 1999;Polonsky et al 2000;Kastner & Ungerleider 2000) (see also review by Blake & Logothetis (2002)), as the synaptic activity produced by lateral or feedback input is visible with imaging but not always with single-unit recordings. A good example is the measurement of the effects of spatial attention on neural activation.…”

“…Attentional effects on the neurons of striate cortex have indeed been very difficult to measure in monkey electrophysiology experiments (Luck et al 1997;McAdams & Maunsell 1999). However, for similar tasks strong attentional effects have been readily measurable with fMRI in human V1 (Tong et al 1998;Gandhi et al 1999;Kastner & Ungerleider 2000). In addition, attentional effects in area V4 were found to be considerably larger in human fMRI than monkey electrophysiology (Kastner et al 1998;Ress et al 2000).…”

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“…LFPs are a prime candidate for correspondence with BOLD signals because synaptic activity constitutes the bulk of neuronal metabolism (Sibson et al 1998), and BOLD responses have been observed in the absence of measurable single-unit activity (Gandhi et al 1999;Blake and Logothetis 2002;Polonsky et al 2000). Nonetheless, the correlation between BOLD signals and MUA was consistently significant although weaker than that with LFP (e.g., Logothetis et al 2001).…”

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“…For one, attending a location boosts the neural activity to elements presented at that location (Brefczynski & DeYoe, 1999;Datta & DeYoe, 2009;Gandhi, Heeger, & Boynton, 1999;Somers, Dale, Seiffert, & Tootell, 1999). It has further been suggested that attending both rival images leads to a boost in the neural response, which increases the effective contrast of rivaling images (Paffen et al, 2006).…”