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Mary Smith, Thomas Sprague, John Serences; Univariate frontoparietal BOLD does not track the magnitude of attentional modulations in visual cortex. Journal of Vision 2015;15(12):1051. doi: 10.1167/15.12.1051.
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© ARVO (1962-2015); The Authors (2016-present)
Directing attention to a region of visual space facilitates the processing of relevant sensory information, resulting in increased neural and BOLD activity in areas of the brain that process this sensory information. This process is thought to be mediated by a frontoparietal “attentional control” network that biases processing in visual cortex. Electrical microstimulation of frontal area FEF in macaques selectively enhances responses in area V4, and also leads to improved behavior (Moore, Fallah 2001, 2004; Armstrong, Moore 2007). If frontoparietal regions such as the FEF are responsible for the differential modulations in early visual cortex across time, then the magnitude of frontoparietal activity should track the magnitude of attentional modulations in early visual cortex on a trial-by-trial basis. Here, we attempted to test this hypothesis using fMRI. Participants directed spatial attention to either the left or right visual field on each trial while performing a demanding spatial attention task. Consistent with previous data, we found that frontoparietal responses were high when early visual responses were high across trials (i.e. an overall yoking between frontoparietal and occipital regions). In addition, visual areas in the hemisphere contralateral to the attended stimulus showed reliably larger BOLD responses compared to areas in the ipsilateral hemisphere. We compared the magnitude of frontoparietal activity and the differential activity in visual areas contra and ipsilateral to the attended stimulus. However, we found no evidence that the overall magnitude of responses in frontoparietal regions track the magnitude of differential attentional responses in early visual cortex. These findings indicate that the univariate magnitude in frontoparietal ROIs is not related to the magnitude of attention effects in visual cortex, at least as measured with the BOLD signal.
Meeting abstract presented at VSS 2015
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