Neuroimaging Laboratory

Santa Lucia di Serino, Italy

Neuroimaging Laboratory

Santa Lucia di Serino, Italy
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Natale E.,Neuroimaging Laboratory | Natale E.,University of Verona | Marzi C.A.,University of Verona | Macaluso E.,Neuroimaging Laboratory
Neuropsychologia | Year: 2010

Targets presented outside the focus of attention trigger stimulus-driven spatial reorienting and activation of the right temporal-parietal junction (rTPJ). However, event-related functional resonance imaging (fMRI) studies that used task-irrelevant non-predictive cues systematically failed to activate rTPJ, suggesting that this region controls reorienting only when attention is shifted between two task-relevant locations. Here we challenge this view showing that non-predictive peripheral cues can affect activity in rTPJ, but only when they share a feature with the target: i.e. when they are set-relevant. Trials including a set-relevant cue plus a target on the uncued/unattended side produced the slowest reaction times and selective activation of the rTPJ. These findings demonstrate that rTPJ is not involved only in reorienting between two task-relevant locations, but engages also when non-predictive cues are set-relevant, thereby, irrespective of voluntary attention and breaches of task-related expectations. © 2009 Elsevier Ltd. All rights reserved.

Santangelo V.,University of Perugia | Santangelo V.,Neuroimaging Laboratory | Macaluso E.,Neuroimaging Laboratory
Journal of Neuroscience | Year: 2013

In everyday life, the brain is bombarded with a multitude of concurrent and competing stimuli. Only some of these enter consciousness and memory. Attention selects relevant signals for in-depth processing depending on current goals, but also on the intrinsic properties of stimuli. We combined behavior, computational modeling, and functional imaging to investigate mechanisms supporting access to memorybased on intrinsic sensory properties. During fMRI scanning,humansubjects were presented with pictures of naturalistic scenes that entailed high levels of competition between possible target objects. Following a retention interval of 8 s, participants judged the location (same/different) of a target object extracted from the initial scene. We found that memory performance at retrieval increased with increasing object salience at encoding, indicating a "prior entry" for salient information. fMRI analyses revealed encoding-related activation in the posterior parietal cortex, selectively for salient objects that were later remembered. Moreover, parietal cortex showed increased functional coupling with the medial-temporal lobe, for remembered objects only. These findings reveal a parietotemporal circuit that integrates available sensory cues (based on attention-grabbing saliency signals) and current memory requirements (storing objects' locations) to encode object-related spatial information in working memory. Copyright © 2013 the authors.

Santangelo V.,Neuroimaging Laboratory | Santangelo V.,University of Perugia | Fagioli S.,University of Rome La Sapienza | Macaluso E.,Neuroimaging Laboratory
NeuroImage | Year: 2010

Traditional views of multisensory integration emphasise the advantage of stimulating or attending to different senses at one single spatial location. We challenge this view demonstrating that in-parallel processing of two sensory modalities can be more efficient when attention is spatially divided rather than focused. We asked subjects to monitor simultaneously vision and audition either at one location (focused attention) or in the two opposite hemifields (divided attention) or to monitor one single modality at one or two locations. Behavioural results demonstrated that the costs of monitoring two modalities, versus one modality, decrease when spatial attention is divided between two separate locations compared with focused attention. Neuroimaging data revealed increased activity in the posterior-parietal cortex (PPC) when monitoring two modalities at different locations, while no specific region was recruited in the focused attention conditions. We suggest that supramodal control and the integration of spatial representations hinders the selection of independent sensory streams when attention is spatially focused, while a greater exploitation of modality-specific resources and the engagement of PPC allows in-parallel processing when attention is spatially divided. © 2009 Elsevier Inc. All rights reserved.

Nardo D.,Neuroimaging Laboratory | Santangelo V.,Neuroimaging Laboratory | Santangelo V.,University of Perugia | Macaluso E.,Neuroimaging Laboratory
Neuron | Year: 2011

In everyday life attention operates within complex and dynamic environments, while laboratory paradigms typically employ simple and stereotyped stimuli. This fMRI study investigated stimulus-driven spatial attention using a virtual-environment video. We explored the influence of bottom-up signals by computing saliency maps of the environment and by introducing attention-grabbing events in the video. We parameterized the efficacy of these signals for the orienting of spatial attention by measuring eye movements and used these parameters to analyze the imaging data. The efficacy of bottom-up signals modulated ongoing activity in dorsal fronto-parietal regions and transient activation of the ventral attention system. Our results demonstrate that the combination of computational, behavioral, and imaging techniques enables studying cognitive functions in ecologically valid contexts. We highlight the central role of the efficacy of stimulus-driven signals in both dorsal and ventral attention systems, with a dissociation of the efficacy of background salience versus distinctive events in the two systems. © 2011 Elsevier Inc.

Kanai R.,University College London | Lloyd H.,St Pauls Girls School | Bueti D.,Neuroimaging Laboratory | Walsh V.,University College London
Experimental Brain Research | Year: 2011

It has been argued that both modality-specific and supramodal mechanisms dedicated to time perception underlie the estimation of interval durations. While it is generally assumed that early sensory areas are dedicated to modality-specific time estimation, we hypothesized that early sensory areas such as the primary visual cortex or the auditory cortex might be involved in time perception independently of the sensory modality of the input. To test this possibility, we examined whether disruption of the primary visual cortex or the auditory cortex would disrupt time estimation of auditory stimuli and visual stimuli using transcranial magnetic stimulation (TMS). We found that disruption of the auditory cortex impaired not only time estimation of auditory stimuli but also impaired that of visual stimuli to the same degree. This finding suggests a supramodal role of the auditory cortex in time perception. On the other hand, TMS over the primary visual cortex impaired performance only in visual time discrimination. These asymmetric contributions of the auditory and visual cortices in time perception may be explained by a superiority of the auditory cortex in temporal processing. Here, we propose that time is primarily encoded in the auditory system and that visual inputs are automatically encoded into an auditory representation in time discrimination tasks. © 2011 Springer-Verlag.

Bueti D.,University College London | Bueti D.,Neuroimaging Laboratory | Bahrami B.,University College London | Walsh V.,University College London | Rees G.,University College London
Journal of Neuroscience | Year: 2010

Anticipating the timing of future events is a necessary precursor to preparing actions and allocating resources to sensory processing. This requires elapsed time to be represented in the brain and used to predict the temporal probability of upcoming events. While neuropsychological, imaging, magnetic stimulation studies, and single-unit recordings implicate the role of higher parietal and motor-related areas in temporal estimation, the role of earlier, purely sensory structures remains more controversial. Here we demonstrate that the temporal probability of expected visual events is encoded not by a single area but by a wide network that importantly includes neuronal populations at the very earliest cortical stages of visual processing. Moreover, we show that activity in those areas changes dynamically in a manner that closely accords with temporal expectations. Copyright © 2010 the authors.

News Article | September 14, 2016

As far as the brain's craving for nicotine is concerned, a person's perception that the cigarette contains nicotine has a key role to play, reports a research from the Center for BrainHealth at the University of Texas in Dallas. Smokers only feel satisfaction when they believe the cigarette they are smoking contains nicotine, if not even the nicotine cigarettes have no effect on their brain. For the study, the researchers included 24 nicotine addicts in four different experiments conducted on different occasions. In the double blind study, the participants were given real cigarettes with nicotine twice and fake placebo cigarettes twice. The participants were first given a placebo cigarette, but were told that it was a real one. On the second visit they were given a real cigarette, but were informed that they were smoking a fake cigarette. The participants then received a real cigarette, knowing that it was a real one on their third visit, and finally they were given a placebo cigarette and was informed that it's a fake one. The investigators used functional magnetic resonance imaging (fMRI) to monitor the neural activity in the insula cortex of the participants. Insula cortex is the region of the brain that controls certain functions of a person including self-awareness and perceptions. This region plays an important role in issues like drug addiction and craving. The participants were subjected to fMRI every time after smoking the cigarette and were also asked to complete a reward learning task. The subjects were also asked to rate their nicotine craving levels before and after every experiment. The fMRI showed significant neural activity when the participants smoked real cigarettes knowing that it contained nicotine. The fMRI results also correlated with both craving and learning signals during the task. However, the participants did not have the same neural activity in the brain when they smoked real cigarette believing that it was a fake one. The study outcome supports several previous findings that said beliefs have a role to play in the effect of drugs on issues like craving and addiction. "We expected the presence of nicotine to show some sort of craving response compared to conditions where the subjects did not receive nicotine despite the belief about the nicotine given, but that was not what we found," said Read Montague, the study's co-author and director of the Human Neuroimaging Laboratory and the Computational Psychiatry Unit at Virginia Tech Carilion Research Institute. The study is published online in the journal Frontiers in Psychiatry. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.

Macaluso E.,Neuroimaging Laboratory
Cortex | Year: 2010

Many everyday situations require combining complex sensory signals about the external world with ongoing goals and expectations. Here I examine the role of attention in this process and consider the underling neural substrates. First, mechanisms of spatial attention in the visual modality are reviewed, emphasising the involvement of fronto-parietal cortex. Spatial attention takes into account endogenous factors, e.g., information about behavioural relevance, as well as signals arising from the external world (stimulus-driven control). Stimulus-driven control is thought to take place automatically and independently from endogenous factors. However, recent findings demonstrate that endogenous and stimulus-driven mechanisms co-operate, jointly contributing for the selection of the relevant spatial location. Next, I will turn to studies of multisensory spatial attention. These have shown that attention control in fronto-parietal cortex operates supramodally. Supramodal control exerts top-down influences onto sensory-specific areas, enhancing the processing of stimuli at the attended location irrespective of modality. Unlike unimodal visual attention, but in line with traditional views of multisensory integration, multisensory attention can operate in a fully automatic manner regardless of relevance and task-set. I discuss these findings in relation to functional/anatomical pathways that may mediate multisensory attention control, highlighting possible links between spatial attention and multisensory integration of space. © 2009 Elsevier Srl.

Nardo D.,Neuroimaging Laboratory | Santangelo V.,Neuroimaging Laboratory | Santangelo V.,University of Perugia | Macaluso E.,Neuroimaging Laboratory
Human Brain Mapping | Year: 2014

Previous studies on crossmodal spatial orienting typically used simple and stereotyped stimuli in the absence of any meaningful context. This study combined computational models, behavioural measures and functional magnetic resonance imaging to investigate audiovisual spatial interactions in naturalistic settings. We created short videos portraying everyday life situations that included a lateralised visual event and a co-occurring sound, either on the same or on the opposite side of space. Subjects viewed the videos with or without eye-movements allowed (overt or covert orienting). For each video, visual and auditory saliency maps were used to index the strength of stimulus-driven signals, and eye-movements were used as a measure of the efficacy of the audiovisual events for spatial orienting. Results showed that visual salience modulated activity in higher-order visual areas, whereas auditory salience modulated activity in the superior temporal cortex. Auditory salience modulated activity also in the posterior parietal cortex, but only when audiovisual stimuli occurred on the same side of space (multisensory spatial congruence). Orienting efficacy affected activity in the visual cortex, within the same regions modulated by visual salience. These patterns of activation were comparable in overt and covert orienting conditions. Our results demonstrate that, during viewing of complex multisensory stimuli, activity in sensory areas reflects both stimulus-driven signals and their efficacy for spatial orienting; and that the posterior parietal cortex combines spatial information about the visual and the auditory modality. © 2013 Wiley Periodicals, Inc.

Santangelo V.,University of Perugia | Santangelo V.,Neuroimaging Laboratory | Macaluso E.,Neuroimaging Laboratory
Human Brain Mapping | Year: 2013

Previous studies have indicated that increasing working memory (WM) load can affect the attentional selection of signals originating from one object/location. Here we assessed whether WM load affects also the selection of multiple objects/locations (divided attention). Participants monitored either two object-categories (vs. one category; object-based divided attention) or two locations (vs. one location; space-based divided attention) while maintaining in WM either a variable number of objects (object-based WM load) or locations (space-based WM load). Behavioural results showed that WM load affected attentional performance irrespective of divided or focused attention. However, fMRI results showed that the activity associated with object-based divided attention increased linearly with increasing object-based WM load in the left and right intraparietal sulcus (IPS); while, in the same areas, activity associated with space-based divided attention was not affected by any type of WM load. These findings support the hypothesis that WM contributes to the maintenance of resource-demanding attentional sets in a domain-specific manner. Moreover, the dissociable impact of WM load on performance and brain activity suggests that increased IPS activation reflects a recruitment of additional, domain-specific processing resources that enable dual-task performance under conditions of high WM load and high attentional demand. © 2011 Wiley Periodicals, Inc.

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