Involvement of striate and extrastriate visual cortical areas in spatial attention

Abstract

We investigated the cortical mechanisms of visual-spatial attention while subjects discriminated patterned targets within distractor arrays. Functional magnetic resonance imaging (fMRI) was used to map the boundaries of retinotopic visual areas and to localize attention-related changes in neural activity within several of those areas, including primary visual (striate) cortex. Event-related potentials (ERPs) and modeling of their neural sources, however, indicated that the initial sensory input to striate cortex at 50-55 milliseconds after the stimulus was not modulated by attention. The earliest facilitation of attended signals was observed in extrastriate visual areas, at 70-75 milliseconds. We hypothesize that the striate cortex modulation found with fMRI may represent a delayed, re-entrant feedback from higher visual areas or a sustained biasing of striate cortical neurons during attention. ERP recordings provide critical temporal information for analyzing the functional neuroanatomy of visual attention.

Selective and interactive neural correlates of visual dimension changes and response changes

“…The current activation pattern supports this view: there was a large activation in right fusiform gyrus, at a location that has previously been reported to be a potential source of the P1 event-related electric brain potential, which itself is modulated by selective attention (Heinze et al, 1994). Likewise, the cortex at the banks of the intraoccipital sulcus, where we found increased activation following dimension changes, has also been reported to be modulated by selective attention in an fMRI study and to be a second potential source of the P1 (Martinez et al, 1999; separate ventral and dorsal P1 sources may be due to the retinotopic organization of higher-tier visual cortices).…”

State-dependent attention modulation of human primary visual cortex: A high density ERP study

“…Whereas amplitude variations of the P1 component as a function of attention selection have repeatedly been reported in the ERP literature (e.g., Hillyard and Annlo-Vento, 1998;Luck et al, 1990;Mangun and Hillyard, 1988;Martinez et al, 1999), only few studies have focused on this component when it is generated in response to desynchronized, task-unrelated stimuli presented at an unattended spatial location, as in the present case. While in one study (Handy et al, 2001, experiment 2), irrelevant probe stimuli elicited smaller P1 responses when the task at fixation was characterized by HL, another did not find variations of the P1 to irrelevant unattended stimuli when load was systematically changed (Barnhardt et al, 2008).…”

“…This component usually peaks ~50-100 ms post-stimulus onset over occipitoparietal leads, and its main generators are classically ascribed to pyramidal neurons of layers III and V covering the fundus of the calcarine fissure (Clark et al, 1995;Di Russo et al, 2002;Foxe and Simpson, 2002;Jeffreys and Axford, 1972). The C1 has for a long time been described as being resistant to modulatory effects exerted by distant fronto-parietal attention control regions onto lower tier visual cortex (Clark and Hillyard, 1996;Handy et al, 2001;Martinez et al, 1999). More recently, systematic C1 amplitude changes have been reported with top-down cognitive manipulations (see Rauss et al, 2011a for a recent review), including perceptual learning and expertise (Bao et al, 2010;Jin et al, 2010;Pourtois et al, 2008), emotional valence (Eldar et al, 2010;Halgren et al, 2000;Pourtois et al, 2004;West et al, 2011), and featurebased or spatial attention (Karns and Knight, 2009;Kelly et al, 2008;Proverbio et al, 2010;Zani and Proverbio, 2009).…”

Cortical plasticity in an early blind musician: an fMRl study

“…BA 18 corresponds to V2 and V3 and BA 19 includes V3a, V4, and V5. In sighted individuals, these regions play a critical role in integrating signals from the primary visual cortex and the function of these regions is known to be modified by top-down signals [18,19]. A number of previous studies have shown that blind individuals may recruit these regions to process both auditory and somatosensory signals [1,6,10,16,17,29 -31,36].…”