Combined spatial and temporal imaging of brain activity during visual selective attention in humans

Abstract

Visual-spatial attention is an essential brain function that enables us to select and preferentially process high priority information in the visual fields. Several brain areas have been shown to participate in the control of spatial attention in humans, but little is known about the underlying selection mechanisms. Non-invasive scalp recordings of event-related potentials (e.r.ps) in humans have shown that attended visual stimuli are preferentially selected as early as 80-90 ms after stimulus onset, but current e.r.p. methods do not permit a precise localization of the participating cortical areas. In this study we combined neuroimaging (positron emission tomography) with e.r.p. recording in order to describe both the cortical anatomy and time course of attentional selection processes. Together these methods showed that visual inputs from attended locations receive enhanced processing in the extrastriate cortex (fusiform gyrus) at 80-130 ms after stimulus onset. These findings reinforce early selection models of 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).…”

A brief introduction to the use of event-related potentials in studies of perception and attention

“…First, we see the C1 component which flips polarity based in whether the eliciting stimulus appears in the upper or lower visual field and is believed to be generated by activity in primary visual cortex (Clark, Fan, & Hillyard, 1995; Clark & Hillyard, 1996; Estevez & Spekreijse, 1974; Jeffreys & Axford, 1972). This initial deflection is followed by the P1 and N1 components as information propagates through the visual system and perceptual analysis is performed (Heinze et al, 1994; Heinze, Mangun, & Hillyard, 1990; Luck, 1995; Vogel & Luck, 2000). 2 Next, we can observe waveforms elicited by the deployment of covert attention to peripheral targets in the visual field (e.g., the N2pc, Eimer, 1996; Luck & Hillyard, 1994a, 1994b) and components associated with categorization of the visual stimulus (e.g., the N2/P3 complex, Kutas, McCarthy, & Donchin, 1977; Pritchard, Shappell, & Brandt, 1991; Sutton, 1979; Sutton et al, 1965).…”

Attention Modulates the Blood Oxygen Level Dependent Response in the Primary Visual Cortex measured with Functional Magnetic Resonance Imaging

“…New developments and techniques in neuroscience (positron emission tomography, magneto-encephalography, and functional magnetic resonance imaging) have opened the possibility of studying the anatomical basis of higher cognitive functions, including attentional processes. These new techniques have made possible the delineation of attentional systems that control alertness [1,2], consciousness [3], spatial visual attention [4], and higher cognitive functions [5]. However, controversy continues as to whether attentional processes modulate neuronal activity within primary sensory areas [6].…”