Recent behavioral and event-related brain potential (ERP) studies have revealed cross-modal interactions in endogenous spatial attention between vision and audition, plus vision and touch. The ...present ERP study investigated whether these interactions reflect supramodal attentional control mechanisms, and whether similar cross-modal interactions also exist between audition and touch. Participants directed attention to the side indicated by a cue to detect infrequent auditory or tactile targets at the cued side. The relevant modality (audition or touch) was blocked. Attentional control processes were reflected in systematic ERP modulations elicited during cued shifts of attention. An anterior negativity contralateral to the cued side was followed by a contralateral positivity at posterior sites. These effects were similar whether the cue signaled which side was relevant for audition or for touch. They also resembled previously observed ERP modulations for shifts of visual attention, thus implicating supramodal mechanisms in the control of spatial attention. Following each cue, single auditory, tactile, or visual stimuli were presented at the cued or uncued side. Although stimuli in task-irrelevant modalities could be completely ignored, visual and auditory ERPs were nevertheless affected by spatial attention when touch was relevant, revealing cross-modal interactions. When audition was relevant, visual ERPs, but not tactile ERPs, were affected by spatial attention, indicating that touch can be decoupled from cross-modal attention when task-irrelevant.
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We used magnetoencephalography (MEG) to assess plasticity of human auditory cortex induced by classical conditioning and contingency reversal. Participants listened to random sequences of high or low ...tones. A first baseline phase presented these without further associations. In phase 2, one of the frequencies (CS + ) was paired with shock on half its occurrences, whereas the other frequency (CS − ) was not. In phase 3, the contingency assigning CS + and CS − was reversed. Conditioned pupil dilation was observed in phase 2 but extinguished in phase 3. MEG revealed that, during phase-2 initial conditioning, the P1m, N1m, and P2m auditory components, measured from sensors over auditory temporal cortex, came to distinguish between CS + and CS − . After contingency reversal in phase 3, the later P2m component rapidly reversed its selectivity (unlike the pupil response) but the earlier P1m did not, whereas N1m showed some new learning but not reversal. These results confirm plasticity of human auditory responses due to classical conditioning, but go further in revealing distinct constraints on different levels of the auditory hierarchy. The later P2m component can reverse affiliation immediately in accord with an updated expectancy after contingency reversal, whereas the earlier auditory components cannot. These findings indicate distinct cognitive and emotional influences on auditory processing.
A regret-induced status quo bias Nicolle, Antoinette; Fleming, Stephen M; Bach, Dominik R ...
The Journal of neuroscience,
2011-Mar-02, 2011-03-02, 20110302, Letnik:
31, Številka:
9
Journal Article
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A suboptimal bias toward accepting the status quo option in decision-making is well established behaviorally, but the underlying neural mechanisms are less clear. Behavioral evidence suggests the ...emotion of regret is higher when errors arise from rejection rather than acceptance of a status quo option. Such asymmetry in the genesis of regret might drive the status quo bias on subsequent decisions, if indeed erroneous status quo rejections have a greater neuronal impact than erroneous status quo acceptances. To test this, we acquired human fMRI data during a difficult perceptual decision task that incorporated a trial-to-trial intrinsic status quo option, with explicit signaling of outcomes (error or correct). Behaviorally, experienced regret was higher after an erroneous status quo rejection compared with acceptance. Anterior insula and medial prefrontal cortex showed increased blood oxygenation level-dependent signal after such status quo rejection errors. In line with our hypothesis, a similar pattern of signal change predicted acceptance of the status quo on a subsequent trial. Thus, our data link a regret-induced status quo bias to error-related activity on the preceding trial.
Ewa Wojciulik 1 , 2 , 3 ,
Nancy Kanwisher 2 , 3 , and
Jon Driver 4
1 Department of Psychology, University of California, Los Angeles, California 90095; 2 Department of Brain and Cognitive Sciences, ...Massachusetts Institute of Technology, Cambridge 02139; 3 Massachusetts General Hospital NMR Center, Charlestown, Massachusetts 02129; and 4 Institute of Cognitive Neuroscience, University College London, London WC1E 6BT, United Kingdom
Wojciulik, Ewa, Nancy Kanwisher, and Jon Driver. Covert visual attention modulates face-specific activity in the human fusiform gyrus: an fMRI study. J. Neurophysiol. 79: 1574-1578, 1998. Several lines of evidence demonstrate that faces undergo specialized processing within the primate visual system. It has been claimed that dedicated modules for such biologically significant stimuli operate in a mandatory fashion whenever their triggering input is presented. However, the possible role of covert attention to the activating stimulus has never been examined for such cases. We used functional magnetic resonance imaging to test whether face-specific activity in the human fusiform face area (FFA) is modulated by covert attention. The FFA was first identified individually in each subject as the ventral occipitotemporal region that responded more strongly to visually presented faces than to other visual objects under passive central viewing. This then served as the region of interest within which attentional modulation was tested independently, using active tasks and a very different stimulus set. Subjects viewed brief displays each comprising two peripheral faces and two peripheral houses (all presented simultaneously). They performed a matching task on either the two faces or the two houses, while maintaining central fixation to equate retinal stimulation across tasks. Signal intensity was reliably stronger during face-matching than house matching in both right- and left-hemisphere predefined FFAs. These results show that face-specific fusiform activity is reduced when stimuli appear outside (vs. inside) the focus of attention. Despite the modular nature of the FFA (i.e., its functional specificity and anatomic localization), face processing in this region nonetheless depends on voluntary attention.
A model of normal attentional function, based on the concept of competitive parallel processing, is used to compare attentional deficits following parietal and frontal lobe lesions. Measurements are ...obtained for visual processing speed, capacity of visual short-term memory (VSTM), spatial bias (bias to left or right hemifield) and top-down control (selective attention based on task relevance). The results show important differences, but also surprising similarities, in parietal and frontal lobe patients. For processing speed and VSTM, deficits are selectively associated with parietal lesions, in particular lesions of the temporoparietal junction. We discuss explanations based on either grey matter or white matter lesions. In striking contrast, measures of attentional weighting (spatial bias and top-down control) are predicted by simple lesion volume. We suggest that attentional weights reflect competition between broadly distributed object representations. Parietal and frontal mechanisms work together, both in weighting by location and weighting by task context.
Attention can enhance processing for relevant information and suppress this for ignored stimuli. However, some residual processing may still arise without attention. Here we presented overlapping ...outline objects at study, with subjects attending to those in one color but not the other. Attended objects were subsequently recognized on a surprise memory test, whereas there was complete amnesia for ignored items on such direct explicit testing; yet reliable behavioral priming effects were found on indirect testing. Event-related fMRI examined neural responses to previously attended or ignored objects, now shown alone in the same or mirror-reversed orientation as before, intermixed with new items. Repetition-related decreases in fMRI responses for objects previously attended and repeated in the same orientation were found in the right posterior fusiform, lateral occipital, and left inferior frontal cortex. More anterior fusiform regions also showed some repetition decreases for ignored objects, irrespective of orientation. View-specific repetition decreases were found in the striate cortex, particularly for previously attended items. In addition, previously ignored objects produced some fMRI response increases in the bilateral lingual gyri, relative to new objects. Selective attention at exposure can thus produce several distinct long-term effects on processing of stimuli repeated later, with neural response suppression stronger for previously attended objects, and some response enhancement for previously ignored objects, with these effects arising in different brain areas. Although repetition decreases may relate to positive priming phenomena, the repetition increases for ignored objects shown here for the first time might relate to processes that can produce “negative priming” in some behavioral studies. These results reveal quantitative and qualitative differences between neural substrates of long-term repetition effects for attended versus unattended objects.
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We used concurrent transcranial magnetic stimulation and functional MRI (TMS‐fMRI) during a visuospatial cueing paradigm in humans, to study the causal role of the right angular gyrus (AG) as a ...source of attentional control. Our findings show that TMS over the right AG (high vs. low intensity) modulates neural responses interhemispherically, in a manner that varies dynamically with the current attentional condition. The behavioural impact of such TMS depended not only on the target hemifield but also on exogenous cue validity, facilitating spatial reorienting to invalidly cued right visual targets. On a neural level, right AG TMS had corresponding interhemispheric effects in the left AG and left retinotopic cortex, including area V1. We conclude that the direction of covert visuospatial attention can involve dynamic interplay between the right AG and remote interconnected regions of the opposite left hemisphere, whereas our findings also suggest that the right AG can influence responses in the retinotopic visual cortex.
Modulations of sensory processing in early visual areas are thought to play an important role in conscious perception. To date, most empirical studies focused on effects occurring
or
visual ...presentation. By contrast, several emerging theories postulate that sensory processing and conscious visual perception may also crucially depend on late top–down influences, potentially arising
a visual display. To provide a direct test of this, we performed an fMRI study using a postcued report procedure. The ability to report a target at a specific spatial location in a visual display can be enhanced behaviorally by symbolic auditory postcues presented shortly
that display. Here we showed that such auditory postcues can enhance target-specific signals in early human visual cortex (V1 and V2). For postcues presented 200 msec after stimulus termination, this target-specific enhancement in visual cortex was specifically associated with correct conscious report. The strength of this modulation predicted individual levels of performance in behavior. By contrast, although later postcues presented 1000 msec after stimulus termination had some impact on activity in early visual cortex, this modulation no longer related to conscious report. These results demonstrate that within a critical time window of a few hundred milliseconds
a visual stimulus has disappeared, successful conscious report of that stimulus still relates to the strength of top–down modulation in early visual cortex. We suggest that, within this critical time window, sensory representation of a visual stimulus is still under construction and so can still be flexibly influenced by top–down modulatory processes.
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We used functional magnetic resonance imaging (fMRI) to study neural correlates of a robust somatosensory illusion that can dissociate tactile perception from physical stimulation. Repeated rapid ...stimulation at the wrist, then near the elbow, can create the illusion of touches at intervening locations along the arm, as if a rabbit hopped along it. We examined brain activity in humans using fMRI, with improved spatial resolution, during this version of the classic cutaneous rabbit illusion. As compared with control stimulation at the same skin sites (but in a different order that did not induce the illusion), illusory sequences activated contralateral primary somatosensory cortex, at a somatotopic location corresponding to the filled-in illusory perception on the forearm. Moreover, the amplitude of this somatosensory activation was comparable to that for veridical stimulation including the intervening position on the arm. The illusion additionally activated areas of premotor and prefrontal cortex. These results provide direct evidence that illusory somatosensory percepts can affect primary somatosensory cortex in a manner that corresponds somatotopically to the illusory percept.
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The duration of sounds can affect the perceived duration of co-occurring visual stimuli. However, it is unclear whether this is limited to amodal processes of duration perception or affects other ...non-temporal qualities of visual perception.
Here, we tested the hypothesis that visual sensitivity--rather than only the perceived duration of visual stimuli--can be affected by the duration of co-occurring sounds. We found that visual detection sensitivity (d') for unimodal stimuli was higher for stimuli of longer duration. Crucially, in a cross-modal condition, we replicated previous unimodal findings, observing that visual sensitivity was shaped by the duration of co-occurring sounds. When short visual stimuli (∼24 ms) were accompanied by sounds of matching duration, visual sensitivity was decreased relative to the unimodal visual condition. However, when the same visual stimuli were accompanied by longer auditory stimuli (∼60-96 ms), visual sensitivity was increased relative to the performance for ∼24 ms auditory stimuli. Across participants, this sensitivity enhancement was observed within a critical time window of ∼60-96 ms. Moreover, the amplitude of this effect correlated with visual sensitivity enhancement found for longer lasting visual stimuli across participants.
Our findings show that the duration of co-occurring sounds affects visual perception; it changes visual sensitivity in a similar way as altering the (actual) duration of the visual stimuli does.
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