Event-related brain potentials in the study of visual selective attention

Abstract

Event-related brain potentials (ERPs) provide high-resolution measures of the time course of neuronal activity patterns associated with perceptual and cognitive processes. New techniques for ERP source analysis and comparisons with data from blood-f low neuroimaging studies enable improved localization of cortical activity during visual selective attention. ERP modulations during spatial attention point toward a mechanism of gain control over information f low in extrastriate visual cortical pathways, starting about 80 ms after stimulus onset. Paying attention to nonspatial features such as color, motion, or shape is manifested by qualitatively different ERP patterns in multiple cortical areas that begin with latencies of 100-150 ms. The processing of nonspatial features seems to be contingent upon the prior selection of location, consistent with early selection theories of attention and with the hypothesis that spatial attention is ''special.''To analyze the neural bases of a cognitive system such as attention, we must identify not only the participating brain regions but also the temporal microstructure of information flow among the regions involved. Although imaging methods that register changes in cerebral blood flow (positron emission tomography, PET, and functional magnetic resonance imaging, fMRI) have proven highly effective for defining the anatomical areas and networks that are activated during cognitive operations (1), these methods (for the present at least) are severely limited in their ability to reveal the temporal patterns of activation within these networks. Indeed, the intrinsically sluggish nature of the hemodynamic response to increased neuronal activity may place a lower limit of the order of hundreds of milliseconds on the time resolution capability of blood-flow imaging techniques.Fine-grained information about the temporal structure of neural activation patterns can be obtained through noninvasive recordings of the electrical and magnetic fields that are generated in association with synchronous nerve cell activity. The electrical field potential changes that are time-locked with sensory, motor, or cognitive events are termed event-related potentials (ERPs) and consist of a series of voltage oscillations that reflect the time course of neuronal activity with a resolution of the order of milliseconds (2). While surface-recorded ERPs (and the corresponding event-related magnetic fields) faithfully reflect the temporal patterns of activity within neuronal populations, their source locations in the brain can only be estimated and not visualized directly as can be done with PET or fMRI. This indirect estimation of ERP generator locations on the basis of surface-recorded voltage distributions is termed the ''inverse problem.'' While the inverse problem cannot be solved uniquely in any given case, the validity of such indirect source calculations has been enhanced by improved algorithms for modeling intracranial generators in terms of multiple dipoles or sheets of densely packed current ...

Selective visual-spatial attention alters induced gamma band responses in the human EEG

“…A method overcoming this limitations entails manipulating spatial selective attention. As mentioned above, early components of the VEP show a marked enhancement of amplitude when they were evoked by an attended stimulus as compared to when the identical stimulus was unattended (Mangun et al, 1993;Gomez-Gonzales et al, 1994;Mangun, 1995;Anllo-Vento and Hillyard, 1996;Hillyard and Anllo-Vento, 1998;Luck and Ford, 1998). This effect is linked to an ampli®cation of neural responses in those visual pathways related to the processing of the stimulus .…”

“…Therefore it was suggested that a selective attention mechanism focuses these resources to speci®c objects or locations in the visual ®eld without moving the eyes to that location (Hillyard et al, 1995;LaBerge, 1995;Hillyard and Anllo-Vento, 1998). Several metaphors have been used to explain this mechanism.…”

The time course of shape discrimination in the human brain

“…The Selection Negativity comprises a more negative response at the scalp when task-relevant features such as color, or spatial frequency are presented (Anllo-Vento and Hillyard, 1996;Hillyard and Anllo-Vento, 1998). Depth electrode recordings in macaque V4 have suggested that this structure contributes to the surface SN (Mehta et al, 2000).…”

Early attentional processes distinguish selective from global motor inhibitory control: An electrical neuroimaging study

“…Supporting this hypothesis, previous evidence indicates that modulation in attentional demand typically manifests as changes in GFP (Hillyard and Anllo-Vento, 1998;Luck et al, 2000). Moreover, converging data indicate that the 130 ms latency of the GFP modulation corresponds to a period when early attentional processes take place in inhibitory control tasks, subsequently to the very initial stage of the perceptual analyses of the stimuli (see Benikos et al, 2013;Roche et al, 2005;Thomas et al, 2009).…”