Auditory and visual attention assessed with PET

Abstract

Brain mechanisms involved in the maintenance of attention to auditory and visual stimuli at different spatial locations were assessed using positron emission tomography with [15O]water to measure regional cerebral blood flow (rCBF) changes in 13 normal volunteers. Simultaneous auditory [dichotically presented consonant-vowel-consonants (CVCs)] and visual stimuli (vertically oriented, CVCs presented to the left and right of fixation) were presented on every trial. In different conditions subjects attended for targets in a specified stimulus channel (left or right ears or left or right visual fields) while maintaining fixation on a central x. Attending left or right for auditory stimuli increased rCBF in primary auditory cortex in Heschl's gyrus and in temporal lobe auditory association cortices in both hemispheres. Attending left or right for visual stimuli did not change rCBF in primary visual cortex, and only attention to the right significantly increased rCBF in contralateral occipital cortex. Visual attention caused significant rCBF changes in a widespread network that included frontal, parietal, and temporal cortical regions as well as the cerebellum, whereas rCBF changes due to auditory attention were largely localized in the temporal lobes. The results suggest that spatially directed attention is mediated by different mechanisms in the auditory and visual modalities.

Attentional and linguistic interactions in speech perception

“…This general attentional effect is consistent with numerous auditory ERP studies (Hillyard et al, 1973;Woldorff et al, 1993; as well as with prior imaging studies using various speech (Grady et al, 1997;Hashimoto et al, 2000;Hugdahl et al, 2000;Hugdahl et al, 2003;Jancke et al, 2001;Jancke et al, 1999;O'Leary et al, 1997;Pugh et al, 1996;Vingerhoets & Luppens, 2001) and nonspeech (Hall et al, 2000;Jancke et al, 2003) auditory stimuli. Contrasts emphasizing speech sound processing (Speech-Rotated) and lexical processing (Word-Pseudoword) showed not only main effects of these stimulus variables but also strong interactions between attention and stimulus type.…”

“…This approach produces larger selection effects compared with the within-modality selective attention paradigm (i.e., dichotic listening) (Duncan et al, 1997;Rees et al, 2001;Treisman, 1973). Functional imaging studies using this paradigm showed increased activation in brain regions implicated in processing of the attended modality (Johnson & Zatorre, 2005;O'Leary et al, 1997;Woodruff et al, 1996). Petkov and colleagues examined BOLD activations in the auditory cortex to unattended tones during a primary visual task and by the same tones when attended (Petkov et al, 2004).…”

Effects of Smoking Marijuana on Brain Perfusion and Cognition

“…Temporal lobe auditory regions that have consistently shown robust activation during the dichotic task in our laboratory (O'Leary et al 1996(O'Leary et al , 1997, and in others' (Hugdahl et al1999(Hugdahl et al , 2000, did not show rCBF increases that were significantly different from a baseline condition. Additionally, marijuana decreased rCBF in comparison to the baseline condition in brain regions that have been found in a number of studies to be involved in attentional modulation of sensory processing (Chelazzi and Corbetta 2000).…”

Involvement of both prefrontal and inferior parietal cortex in dual-task performance

“…3 The auditory discrimination task was associated with increased cerebral activity in the right superior/middle temporal gyrus (BA 21/22) and the inferior occipital cortex bilaterally (BA 18), while the visual discrimination task was associated with increased cerebral activity in the right superior parietal (BA 7), angular gyrus (BA 39), occipital regions (BA 19), and right fusiform (BA 20). These cerebral areas had previously been found to be associated with sensory discrimination processes [6,18,37,42,57]. 4 We were interested in finding out whether dual-task management involves supplementary activity at the level of the prefrontal cortex (e.g., [20,31]) or more activity only in the posterior cerebral areas already activated by the single tasks (e.g., [10]).…”

“…However, at P < 0.001 uncorrected, foci of activity were observed bilaterally in the superior parietal gyrus for the visual task as well as in the right superior/middle temporal gyrus (BA 21/ 22) for the auditory task and in the right middle and superior occipital (BA 19) (see Table 2). Previous work exploring visual and auditory information processing demonstrated activity in these areas [6,37,42],…”