The Role of the Parietal Lobe in Visual Extinction Studied with Transcranial Magnetic Stimulation

Battelli, Lorella; Alvarez, George A.; Carlson, Thomas A.; Pascual‐Leone, Álvaro

doi:10.1162/jocn.2008.21149

Cited by 84 publications

(110 citation statements)

References 48 publications

(67 reference statements)

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“…This pointer would need to switch back and forth between the targets in a serial manner, leading to less effective modulation of early visual areas. This possibility is consistent with results from transcranial magnetic stimulation (TMS) studies, which show that TMS applied to the parietal lobes impairs tracking in the contralateral hemifield (when multiple objects are tracked; Battelli et al, 2009).…”

Section: Hemifield Independencesupporting

confidence: 88%

Within-Hemifield Competition in Early Visual Areas Limits the Ability to Track Multiple Objects with Attention

2014

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It is much easier to divide attention across the left and right visual hemifields than within the same visual hemifield. Here we investigate whether this benefit of dividing attention across separate visual fields is evident at early cortical processing stages. We measured the steady-state visual evoked potential, an oscillatory response of the visual cortex elicited by flickering stimuli, of moving targets and distractors while human observers performed a tracking task. The amplitude of responses at the target frequencies was larger than that of the distractor frequencies when participants tracked two targets in separate hemifields, indicating that attention can modulate early visual processing when it is divided across hemifields. However, these attentional modulations disappeared when both targets were tracked within the same hemifield. These effects were not due to differences in task performance, because accuracy was matched across the tracking conditions by adjusting target speed (with control conditions ruling out effects due to speed alone). To investigate later processing stages, we examined the P3 component over central-parietal scalp sites that was elicited by the test probe at the end of the trial. The P3 amplitude was larger for probes on targets than on distractors, regardless of whether attention was divided across or within a hemifield, indicating that these higher-level processes were not constrained by visual hemifield. These results suggest that modulating early processing stages enables more efficient target tracking, and that within-hemifield competition limits the ability to modulate multiple target representations within the hemifield maps of the early visual cortex.

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Section: Hemifield Independencesupporting

confidence: 88%

Within-Hemifield Competition in Early Visual Areas Limits the Ability to Track Multiple Objects with Attention

2014

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“…Previous studies had also found that tracking four targets spread across both visual hemifields had little or no additional cost over tracking two targets within a single hemifield Battelli, Alvarez, Carlson & Pascual-Leone, 2009). Our experiment shows that this result holds even when the objects are widely separated to avoid spatial interference and when the total distance traveled by the discs is held constant across trials.…”

Section: Discussionmentioning

confidence: 97%

Resource demands of object tracking and differential allocation of the resource

Chen

Howe

Holcombe

2013

Atten Percept Psychophys

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The attentional processes for tracking moving objects may be largely hemisphere-specific. Indeed, in our first two experiments the maximum object speed (speed limit) for tracking targets in one visual hemifield (left or right) was not significantly affected by a requirement to track additional targets in the other hemifield. When the additional targets instead occupied the same hemifield as the original targets, the speed limit was reduced. At slow target speeds, however, adding a second target to the same hemifield had little effect. At high target speeds, the cost of adding a same-hemifield second target was approximately as large as would occur if observers could only track one of the targets. This shows that performance with a fast-moving target is very sensitive to the amount of resource allocated. In a third experiment, we investigated whether the resources for tracking can be distributed unequally between two targets. The speed limit for a given target was higher if the second target was slow rather than fast, suggesting that more resource was allocated to the faster of the two targets. This finding was statistically significant only for targets presented in the same hemifield, consistent with the theory of independent resources in the two hemifields. Some limited evidence was also found for resource sharing across hemifields, suggesting that attentional tracking resources may not be entirely hemifield-specific. Together, these experiments indicate that the largely hemisphere-specific tracking resource can be differentially allocated to faster targets.

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“…Social interactions depend on correctly perceiving subtle dynamics in facial and bodily movements (Aviezer et al, 2012), which reveal the emotions, dispositions, and intentions of others. Our cross-methodological results (correlational, behavioral, and causal) suggest that the role of pSTS in social cognition may particularly relate to the processing of such dynamic social information.…”

Section: Discussionmentioning

confidence: 99%

Distinct Neural Mechanisms for Body Form and Body Motion Discriminations

et al. 2014

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Actions can be understood based on form cues (e.g., static body posture) as well as motion cues (e.g., gait patterns). A fundamental debate centers on the question of whether the functional and neural mechanisms processing these two types of cues are dissociable. Here, using fMRI, psychophysics, and transcranial magnetic stimulation (TMS), all within the same human participants, we show that mechanisms underlying body form and body motion processing are functionally and neurally distinct. Multivoxel fMRI activity patterns in the extrastriate body area (EBA), but not in the posterior superior temporal sulcus (pSTS), carried cue invariant information about the body form of an acting human. Conversely, multivoxel patterns in pSTS, but not in EBA, carried information about the body motion of the same actor. In a psychophysical experiment, we selectively impaired body form and body motion discriminations by manipulating different visual cues: misaligning the ellipses that made up a dynamic walker stimulus selectively disrupted body form discriminations, while varying the presentation duration of the walker selectively affected body motion discriminations. Finally, a TMS experiment revealed causal evidence for a double-dissociation between neural mechanisms underlying body form and body motion discriminations: TMS over EBA selectively disrupted body form discrimination, whereas TMS over pSTS selectively disrupted body motion discrimination. Together, these findings reveal complementing but dissociable functions of EBA and pSTS during action perception. They provide constraints for theoretical and computational models of action perception by showing that action perception involves at least two parallel pathways that separately contribute to the understanding of others' behavior.

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The Role of the Parietal Lobe in Visual Extinction Studied with Transcranial Magnetic Stimulation

Cited by 84 publications

References 48 publications

Within-Hemifield Competition in Early Visual Areas Limits the Ability to Track Multiple Objects with Attention

Within-Hemifield Competition in Early Visual Areas Limits the Ability to Track Multiple Objects with Attention

Resource demands of object tracking and differential allocation of the resource

Distinct Neural Mechanisms for Body Form and Body Motion Discriminations

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