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1.
Sci Rep ; 14(1): 7943, 2024 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-38575698

RESUMO

Memory retrieval entails dynamic interactions between the medial temporal lobe and areas in the parietal and frontal cortices. Here, we tested the hypothesis that effective connectivity between the precuneus, in the medial parietal cortex, and the medial temporal cortex contributes to the subjective quality of remembering objects together with information about their rich spatio-temporal encoding context. During a 45 min encoding session, the participants were presented with pictures of objects while they actively explored a virtual town. The following day, under fMRI, participants were presented with images of objects and had to report whether: they recognized the object and could remember the place/time of encoding, the object was familiar only, or the object was new. The hippocampus/parahippocampus, the precuneus and the ventro-medial prefrontal cortex activated when the participants successfully recognized objects they had seen in the virtual town and reported that they could remember the place/time of these events. Analyses of effective connectivity showed that the influence exerted by the precuneus on the medial temporal cortex mediates this effect of episodic recollection. Our findings demonstrate the role of the inter-regional connectivity in mediating the subjective experience of remembering and underline the relevance of studying memory in contextually-rich conditions.


Assuntos
Memória Episódica , Lobo Temporal , Humanos , Lobo Temporal/diagnóstico por imagem , Lobo Parietal/diagnóstico por imagem , Memória , Rememoração Mental , Hipocampo , Imageamento por Ressonância Magnética , Mapeamento Encefálico/métodos
2.
Neuroimage ; 286: 120514, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38211706

RESUMO

Visual attention can be guided by statistical regularities in the environment, that people implicitly learn from past experiences (statistical learning, SL). Moreover, a perceptually salient element can automatically capture attention, gaining processing priority through a bottom-up attentional control mechanism. The aim of our study was to investigate the dynamics of SL and if it shapes attentional target selection additively with salience processing, or whether these mechanisms interact, e.g. one gates the other. In a visual search task, we therefore manipulated target frequency (high vs. low) across locations while, in some trials, the target was salient in terms of colour. Additionally, halfway through the experiment, the high-frequency location changed to the opposite hemifield. EEG activity was simultaneously recorded, with a specific interest in two markers related to target selection and post-selection processing, respectively: N2pc and SPCN. Our results revealed that both SL and saliency significantly enhanced behavioural performance, but also interacted with each other, with an attenuated saliency effect at the high-frequency target location, and a smaller SL effect for salient targets. Concerning processing dynamics, the benefit of salience processing was more evident during the early stage of target selection and processing, as indexed by a larger N2pc and early-SPCN, whereas SL modulated the underlying neural activity particularly later on, as revealed by larger late-SPCN. Furthermore, we showed that SL was rapidly acquired and adjusted when the spatial imbalance changed. Overall, our findings suggest that SL is flexible to changes and, combined with salience processing, jointly contributes to establishing attentional priority.


Assuntos
Eletroencefalografia , Percepção Visual , Humanos , Tempo de Reação
3.
Hum Brain Mapp ; 44(18): 6439-6458, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-37877138

RESUMO

Attention selects behaviorally relevant inputs for in-depth processing. Beside the role of traditional signals related to goal-directed and stimulus-driven control, a debate exists regarding the mechanisms governing the effect of statistical regularities on attentional selection, and how these are integrated with other control signals. Using a visuo-spatial search task under fMRI, we tested the joint effects of statistical regularities and stimulus-driven salience. We found that both types of signals modulated occipital activity in a spatially specific manner. Salience acted primarily by reducing the attention bias towards the target location when associated with irrelevant distractors, while statistical regularities reduced this attention bias when the target was presented at a low probability location, particularly at the lower levels of the visual hierarchy. In addition, we found that both statistical regularities and salience activated the dorsal frontoparietal network. Additional exploratory analyses of functional connectivity revealed that only statistical regularities modulated the inter-regional coupling between the posterior parietal cortex and the occipital cortex. These results show that statistical regularities and salience signals are both spatially represented at the occipital level, but that their integration into attentional processing priorities relies on dissociable brain mechanisms.


Assuntos
Encéfalo , Lobo Occipital , Humanos , Lobo Occipital/diagnóstico por imagem , Lobo Parietal , Imageamento por Ressonância Magnética
4.
Atten Percept Psychophys ; 85(6): 1819-1833, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37264294

RESUMO

The present study aims to investigate how the competition between visual elements is solved by top-down and/or statistical learning (SL) attentional control (AC) mechanisms when active together. We hypothesized that the "winner" element that will undergo further processing is selected either by one AC mechanism that prevails over the other, or by the joint activity of both mechanisms. To test these hypotheses, we conducted a visual search experiment that combined an endogenous cueing protocol (valid vs. neutral cue) and an imbalance of target frequency distribution across locations (high- vs. low-frequency location). The unique and combined effects of top-down control and SL mechanisms were measured on behaviour and amplitudes of three evoked-response potential (ERP) components (i.e., N2pc, P1, CNV) related to attentional processing. Our behavioural results showed better performance for validly cued targets and for targets in the high-frequency location. The two factors were found to interact, so that SL effects emerged only in the absence of top-down guidance. Whereas the CNV and P1 only displayed a main effect of cueing, for the N2pc we observed an interaction between cueing and SL, revealing a cueing effect for targets in the low-frequency condition, but not in the high-frequency condition. Thus, our data support the view that top-down control and SL work in a conjoint, integrated manner during target selection. In particular, SL mechanisms are reduced or even absent when a fully reliable top-down guidance of attention is at play.


Assuntos
Sinais (Psicologia) , Aprendizagem , Humanos , Tempo de Reação/fisiologia , Aprendizagem/fisiologia , Potenciais Evocados , Eletroencefalografia , Percepção Visual/fisiologia
5.
Atten Percept Psychophys ; 85(3): 705-717, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36788197

RESUMO

We examined the effect of combined top-down and bottom-up attentional control sources in easy and difficult visual search tasks. Applying a new analysis on previously acquired data, we focused on the sustained posterior contralateral negativity (SPCN) and the response-locked posterior contralateral negativity (RLpcN), to better understand processes following target selection. We used the signed-area approach to measure the negative area, where the signal was either locked to the target or the response onsets. We further split the RLpcN into an early and a late segment to capture the dynamics of selection and post-selection processes. In Experiment 1, participants reported the orientation of a uniquely tilted target. In Experiment 2, participants reported the position of a small gap within the uniquely tilted target. In both experiments, endogenous cues manipulated top-down attention (valid vs. neutral), and salient color singletons (either the target or a distractor) manipulated bottom-up attention. We hypothesized that the SPCN and the later segment of the RLpcN would be modulated by task difficulty and target salience, as they are associated with post-selection processes, such as response selection and working memory. The early segment of the RLpcN was hypothesized to be modulated by the cueing manipulation and presence of a salient distractor, as they affect target selection. An effect of distractor presence was observed on the early segment of the RLpcN, and our results further supported the hypotheses regarding the SPCN and the later segment of the RLpcN, providing novel insights into post-selection processes in visual search.


Assuntos
Sinais (Psicologia) , Memória de Curto Prazo , Humanos , Tempo de Reação/fisiologia , Memória de Curto Prazo/fisiologia , Estimulação Luminosa , Percepção Visual/fisiologia
6.
Sci Rep ; 12(1): 20308, 2022 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-36434040

RESUMO

Eye movements and other rich data obtained in virtual reality (VR) environments resembling situations where symptoms are manifested could help in the objective detection of various symptoms in clinical conditions. In the present study, 37 children with attention deficit hyperactivity disorder and 36 typically developing controls (9-13 y.o) played a lifelike prospective memory game using head-mounted display with inbuilt 90 Hz eye tracker. Eye movement patterns had prominent group differences, but they were dispersed across the full performance time rather than associated with specific events or stimulus features. A support vector machine classifier trained on eye movement data showed excellent discrimination ability with 0.92 area under curve, which was significantly higher than for task performance measures or for eye movements obtained in a visual search task. We demonstrated that a naturalistic VR task combined with eye tracking allows accurate prediction of attention deficits, paving the way for precision diagnostics.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade , Realidade Virtual , Criança , Humanos , Movimentos Oculares , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Análise e Desempenho de Tarefas
7.
Hum Brain Mapp ; 43(15): 4529-4539, 2022 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-35695003

RESUMO

Visuospatial attention is strongly lateralized, with the right hemisphere commonly exhibiting stronger activation and connectivity patterns than the left hemisphere during attentive processes. However, whether such asymmetry influences inter-hemispheric information transfer and behavioral performance is not known. Here we used a region of interest (ROI) and network-based approach to determine steady-state fMRI functional connectivity (FC) in the whole cerebral cortex during a leftward/rightward covert visuospatial attention task. We found that the global FC topology between either ROIs or networks was independent on the attended side. The side of attention significantly modulated FC strength between brain networks, with leftward attention primarily involving the connections of the right visual network with dorsal and ventral attention networks in both the left and right hemisphere. High hemispheric functional segregation significantly correlated with faster target detection response times (i.e., better performance). Our findings suggest that the dominance of the right hemisphere in visuospatial attention is associated with an hemispheric functional segregation that is beneficial for behavioral performance.


Assuntos
Lateralidade Funcional , Imageamento por Ressonância Magnética , Córtex Cerebral , Lateralidade Funcional/fisiologia , Humanos
8.
Neuroimage ; 255: 119206, 2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35427770

RESUMO

Visuo-spatial attention prioritizes the processing of relevant inputs via different types of signals, including current goals and stimulus salience. Complex mixtures of these signals engage in everyday life situations, but little is known about how these signals jointly modulate distributed patterns of activity across the occipital regions that represent visual space. Here, we measured spatio-topic, quadrant-specific occipital activity during the processing of visual displays containing both task-relevant targets and salient color-singletons. We computed spatial bias vectors indexing the effect of attention in 2D space, as coded by distributed activity in the occipital cortex. We found that goal-directed spatial attention biased activity towards the target and that salience further modulated this endogenous effect: salient distractors decreased the spatial bias, while salient targets increased it. Analyses of effective connectivity revealed that the processing of salient distractors relied on the modulation of the bidirectional connectivity between the occipital and the posterior parietal cortex, as well as the modulation of the lateral interactions within the occipital cortex. These findings demonstrate that goal-directed attention and salience jointly contribute to shaping processing priorities in the occipital cortex and highlight that multiple functional paths determine how spatial information about these signals is distributed across occipital regions.


Assuntos
Atenção , Imageamento por Ressonância Magnética , Mapeamento Encefálico , Humanos , Lobo Occipital , Lobo Parietal , Estimulação Luminosa , Percepção Espacial , Percepção Visual
9.
Psychophysiology ; 59(6): e14002, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35060631

RESUMO

We examined the effect of combined top-down and bottom-up attentional control sources, using known attention-related EEG components that are thought to reflect target selection (N2pc) and distractor suppression (PD ). We used endogenous cues (valid vs. neutral) for top-down attentional control, and salience in the form of color singletons (either the target or a distractor) for bottom-up attentional control in visual search. Crucially, in two experiments, the task was of increasing difficulty, reporting the orientation of a tilted target (Experiment 1), or the position of a small gap within the target among tilted non-targets (Experiment 2). Our results showed strong cueing effects on RT and accuracy in both experiments, demonstrating a general facilitation of responses to validly cued targets. Whereas the processing of salient targets was not improved compared with non-salient targets, the presence of a salient distractor consistently worsened performance. The N2pc and PD were only observed in trials where targets were preceded by neutral cues in Experiment 1, and for validly cued targets and salient neutrally cued targets in Experiment 2. A cueing effect was found on the PD in Experiment 1, showing an amplitude reduction in trials where the target was validly cued. These results support the idea that bottom-up attentional allocation occurs only when top-down allocation of attention is absent or inefficient. Therefore, these results indicate that attentional selection and suppression during visual search are both influenced by top-down cueing and give support to theories that focus on the interaction between the two types of attention.


Assuntos
Atenção , Eletroencefalografia , Atenção/fisiologia , Sinais (Psicologia) , Humanos , Tempo de Reação/fisiologia , Percepção Visual/fisiologia
10.
Sci Rep ; 11(1): 14577, 2021 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-34272405

RESUMO

Episodic memory entails the storage of events together with their spatio-temporal context and retrieval comprises the subjective experience of a link between the person who remembers and the episode itself. We used an encoding procedure with mobile-phones to generate experimentally-controlled episodes in the real world: object-images were sent to the participants' phone, with encoding durations up to 3 weeks. In other groups of participants, the same objects were encoded during the exploration of a virtual town (45 min) or using a standard laboratory paradigm, with pairs of object/place-images presented in a sequence of unrelated trials (15 min). At retrieval, we tested subjective memory for the objects (remember/familiar) and memory for the context (place and time). We found that accurate and confident context-memory increased the likelihood of "remember" responses, in all encoding contexts. We also tested the participants' ability to judge the temporal-order of the encoded episodes. Using a model of temporal similarity, we demonstrate scale-invariant properties of order-retrieval, but also highlight the contribution of non-chronological factors. We conclude that the mechanisms governing episodic memory retrieval can operate across a wide range of spatio-temporal contexts and that the multi-dimensional nature of the episodic traces contributes to the subjective experience of retrieval.


Assuntos
Encéfalo/fisiologia , Neurociência Cognitiva , Memória Episódica , Rememoração Mental , Reconhecimento Visual de Modelos , Percepção Espacial , Uso do Telefone Celular , Humanos , Propriocepção , Fatores de Tempo , Realidade Virtual
11.
Brain Struct Funct ; 226(4): 989-1006, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33533985

RESUMO

Previous studies demonstrated that long-term memory related to object-position in natural scenes guides visuo-spatial attention during subsequent search. Memory-guided attention has been associated with the activation of memory regions (the medial-temporal cortex) and with the fronto-parietal attention network. Notably, these circuits represent external locations with different frames of reference: egocentric (i.e., eyes/head-centered) in the dorsal attention network vs. allocentric (i.e., world/scene-centered) in the medial temporal cortex. Here we used behavioral measures and fMRI to assess the contribution of egocentric and allocentric spatial information during memory-guided attention. At encoding, participants were presented with real-world scenes and asked to search for and memorize the location of a high-contrast target superimposed in half of the scenes. At retrieval, participants viewed again the same scenes, now all including a low-contrast target. In scenes that included the target at encoding, the target was presented at the same scene-location. Critically, scenes were now shown either from the same or different viewpoint compared with encoding. This resulted in a memory-by-view design (target seen/unseen x same/different view), which allowed us teasing apart the role of allocentric vs. egocentric signals during memory-guided attention. Retrieval-related results showed greater search-accuracy for seen than unseen targets, both in the same and different views, indicating that memory contributes to visual search notwithstanding perspective changes. This view-change independent effect was associated with the activation of the left lateral intra-parietal sulcus. Our results demonstrate that this parietal region mediates memory-guided attention by taking into account allocentric/scene-centered information about the objects' position in the external world.


Assuntos
Córtex Cerebral , Lobo Parietal , Humanos , Imageamento por Ressonância Magnética , Lobo Parietal/diagnóstico por imagem , Percepção Espacial , Lobo Temporal/diagnóstico por imagem
12.
Hum Brain Mapp ; 42(6): 1805-1828, 2021 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-33528884

RESUMO

In-scanner head motion represents a major confounding factor in functional connectivity studies and it raises particular concerns when motion correlates with the effect of interest. One such instance regards research focused on functional connectivity modulations induced by sustained cognitively demanding tasks. Indeed, cognitive engagement is generally associated with substantially lower in-scanner movement compared with unconstrained, or minimally constrained, conditions. Consequently, the reliability of condition-dependent changes in functional connectivity relies on effective denoising strategies. In this study, we evaluated the ability of common denoising pipelines to minimize and balance residual motion-related artifacts between resting-state and task conditions. Denoising pipelines-including realignment/tissue-based regression, PCA/ICA-based methods (aCompCor and ICA-AROMA, respectively), global signal regression, and censoring of motion-contaminated volumes-were evaluated according to a set of benchmarks designed to assess either residual artifacts or network identifiability. We found a marked heterogeneity in pipeline performance, with many approaches showing a differential efficacy between rest and task conditions. The most effective approaches included aCompCor, optimized to increase the noise prediction power of the extracted confounding signals, and global signal regression, although both strategies performed poorly in mitigating the spurious distance-dependent association between motion and connectivity. Censoring was the only approach that substantially reduced distance-dependent artifacts, yet this came at the great cost of reduced network identifiability. The implications of these findings for best practice in denoising task-based functional connectivity data, and more generally for resting-state data, are discussed.


Assuntos
Cérebro/diagnóstico por imagem , Cérebro/fisiologia , Cognição/fisiologia , Conectoma/métodos , Conectoma/normas , Adulto , Artefatos , Percepção Auditiva/fisiologia , Cérebro/anatomia & histologia , Conjuntos de Dados como Assunto , Movimentos da Cabeça , Humanos , Imageamento por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/normas , Memória de Curto Prazo/fisiologia , Descanso/fisiologia
13.
Exp Aging Res ; 47(1): 1-20, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33107393

RESUMO

How prospective memory (PM) weakens with increasing age has been largely debated. We hypothesized that automatic and strategic PM processes, respectively mediated by focal and non-focal cues, are differently affected by aging, even starting from 50-60 years of age. We investigated this issue using a 2 × 2 design in which focal and non-focal experimental conditions were created by varying the conjoint nature of the ongoing task (lexical decision vs. syllable matching tasks) and the PM cue (words vs. syllables). In the whole-brain analysis we found that the left inferior frontal gyrus and the middle cingulate cortex were more activated when young compared to older individuals performed a PM task; moreover, the anterior cingulate cortex was selectively activated during non-focal PM when the cues were words. In a region-of-interest analysis we observed that the medial and the lateral portions of the rostral prefrontal cortex were associated with the focal and non-focal conditions respectively, more in young than in older adults. Our findings provide evidence in support of early age-related differences in automatic/strategic PM functioning.


Assuntos
Sinais (Psicologia) , Memória Episódica , Idoso , Envelhecimento , Humanos , Imageamento por Ressonância Magnética , Tempo de Reação
14.
Neuropharmacology ; 182: 108377, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33137343

RESUMO

Visuo-spatial attentional orienting is fundamental to selectively process behaviorally relevant information, depending on both low-level visual attributes of stimuli in the environment and higher-level factors, such as goals, expectations and prior knowledge. Growing evidence suggests an impact of the locus-cœruleus-norepinephrine (LC-NE) system in attentional orienting that depends on taskcontext. Nonetheless, most of previous studies used visual displays encompassing a target and various distractors, often preceded by cues to orient the attentional focus. This emphasizes the contribution of goal-driven processes, at the expense of other factors related to the stimulus content. Here, we aimed to determine the impact of NE on attentional orienting in more naturalistic conditions, using complex images and without any explicit task manipulation. We tested the effects of atomoxetine (ATX) injections, a NE reuptake inhibitor, on four monkeys during free viewing of images belonging to three categories: landscapes, monkey faces and scrambled images. Analyses of the gaze exploration patterns revealed, first, that the monkeys spent more time on each fixation under ATX compared to the control condition, regard less of the image content. Second, we found that, depending on the image content, ATX modulated the impact of low-level visual salience on attentional orienting. This effect correlated with the effect of ATX on the number and duration of fixations. Taken together, our results demonstrate that ATX adjusts the contribution of salience on attentional orienting depending on the image content, indicative of its role in balancing the role of stimulus-driven and top-down control during free viewing of complex stimuli.


Assuntos
Inibidores da Captação Adrenérgica/farmacologia , Cloridrato de Atomoxetina/farmacologia , Atenção/efeitos dos fármacos , Movimentos Oculares/efeitos dos fármacos , Estimulação Luminosa/métodos , Tempo de Reação/efeitos dos fármacos , Animais , Atenção/fisiologia , Movimentos Oculares/fisiologia , Feminino , Macaca mulatta , Tempo de Reação/fisiologia
15.
PLoS One ; 15(6): e0234695, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32559213

RESUMO

When looking at a speaking person, the analysis of facial kinematics contributes to language discrimination and to the decoding of the time flow of visual speech. To disentangle these two factors, we investigated behavioural and fMRI responses to familiar and unfamiliar languages when observing speech gestures with natural or reversed kinematics. Twenty Italian volunteers viewed silent video-clips of speech shown as recorded (Forward, biological motion) or reversed in time (Backward, non-biological motion), in Italian (familiar language) or Arabic (non-familiar language). fMRI revealed that language (Italian/Arabic) and time-rendering (Forward/Backward) modulated distinct areas in the ventral occipito-temporal cortex, suggesting that visual speech analysis begins in this region, earlier than previously thought. Left premotor ventral (superior subdivision) and dorsal areas were preferentially activated with the familiar language independently of time-rendering, challenging the view that the role of these regions in speech processing is purely articulatory. The left premotor ventral region in the frontal operculum, thought to include part of the Broca's area, responded to the natural familiar language, consistent with the hypothesis of motor simulation of speech gestures.


Assuntos
Área de Broca/fisiologia , Gestos , Idioma , Córtex Motor/fisiologia , Lobo Occipital/fisiologia , Fala/fisiologia , Lobo Temporal/fisiologia , Adulto , Comportamento , Discriminação Psicológica , Feminino , Humanos , Modelos Lineares , Imageamento por Ressonância Magnética , Masculino , Análise e Desempenho de Tarefas , Adulto Jovem
16.
Front Physiol ; 11: 422, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32457647

RESUMO

Spontaneous oscillations of the blood oxygenation level-dependent (BOLD) signal are spatially synchronized within specific brain networks and are thought to reflect synchronized brain activity. Networks are modulated by the performance of a task, even if the exact features and degree of such modulations are still elusive. The presence of networks showing anticorrelated fluctuations lend initially to suppose that a competitive relationship between the default mode network (DMN) and task positive networks (TPNs) supports the efficiency of brain processing. However, more recent results indicate that cooperative and competitive dynamics between networks coexist during task performance. In this study, we used graph analysis to assess the functional relevance of the topological reorganization of brain networks ensuing the execution of a steady state working-memory (WM) task. Our results indicate that the performance of an auditory WM task is associated with a switching between different topological configurations of several regions of specific networks, including frontoparietal, ventral attention, and dorsal attention areas, suggesting segregation of ventral attention regions in the presence of increased overall integration. However, the correct execution of the task requires integration between components belonging to all the involved networks.

17.
J Neurosci ; 40(10): 2129-2138, 2020 03 04.
Artigo em Inglês | MEDLINE | ID: mdl-31996453

RESUMO

How temporal and contextual information interactively impact on behavior and brain activity during the retrieval of temporal order about naturalistic episodes remains incompletely understood. Here, we used fMRI to examine the effects of contextual signals derived from the content of the movie on the neural correlates underlying memory retrieval of temporal-order in human subjects of both sexes. By contrasting SAME versus DIFF storyline conditions during the retrieval of the temporal order of cinematic events, we found that the activation in the precuneus, as well as behavior, are significantly modulated according to storyline condition, supporting our prediction of contextual information contributing to temporal retrieval. We suggest that the precuneus engages in memory retrieval via reconstructive mechanisms, entailing search within a movie-specific, situational knowledge-structure. Furthermore, information-based analyses of multivoxel activity revealed that the precuneus also contains a context-independent linear representation of temporal distances, consistent with a chronological organization of memory traces. We thus put forward that the retrieval of the temporal-order of naturalistic events encoded in rich and dynamic contexts relies on the joint contribution of chronological and reconstructive mechanisms, both of which rely on the medioposterior parietal cortex in humans.SIGNIFICANCE STATEMENT Successful retrieval of episodic memory is dependent on both temporal and contextual signals. However, when contextual signals derived from multiple storylines or narratives are complex and intertwined, the behavioral and neural correlates underpinning the interplay between time and context is not completely understood. Here we characterized the activation level and multivoxel pattern of BOLD signals underlying the modulation of such contextual information during temporal order judgment in the precuneus. Our findings provide us with an elucidation of subprocesses implicating the medial parietal cortex in realizing temporal organization of episodic details.


Assuntos
Memória Episódica , Lobo Parietal/fisiologia , Percepção do Tempo/fisiologia , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Filmes Cinematográficos , Adulto Jovem
18.
Brain Imaging Behav ; 14(4): 1175-1186, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30820859

RESUMO

The rostral prefrontal cortex (rPFC) is crucial in prospective memory (PM) behavior. Several functional magnetic resonance imaging studies showed that its medial (mrPFC) and lateral (lrPFC) portions dissociate during PM tasks. In light of the Multiprocess theory (McDaniel and Einstein 2000), here we tested whether the two portions of the rPFC are dissociable by modulating strategic vs. spontaneous processes during a PM task. We investigated these two processes by means of a 2 × 2 experimental design in which focal vs. non-focal conditions were modulated by varying the conjoint nature of the ongoing task (i.e., lexical decision vs. syllable matching) and the PM cue (words vs. syllables). Using the two portions of the rPFC as regions of interest, we found an effect of the non-focal condition in the lrPFC and, conversely, an effect of the focal condition in the mrPFC. In the whole-brain analysis we found an effect of the non-focal condition in the bilateral intraparietal sulcus, the bilateral middle frontal gyrus, the supplementary motor areas and the vermis of the cerebellum, whereas we found an effect of the focal condition in the ventromedial PFC. Overall, our results show that different brain regions are involved when multiple processes underlying PM behavior are modulated.


Assuntos
Sinais (Psicologia) , Memória Episódica , Atenção , Transtornos Dissociativos , Humanos , Imageamento por Ressonância Magnética , Córtex Pré-Frontal/diagnóstico por imagem , Tempo de Reação
19.
Brain Struct Funct ; 224(6): 2009-2026, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31111208

RESUMO

Previous literature demonstrated that the processing of emotional stimuli can interfere with goal-directed behavior. This has been shown primarily in the context of working memory tasks, but "emotional distraction" may affect also other processes, such as the orienting of visuo-spatial attention. During fMRI, we presented human subjects with emotional stimuli embedded within complex everyday life visual scenes. Emotional stimuli could be either the current target to be searched for or task-irrelevant distractors. Behavioral and eye-movement data revealed faster detection of emotional than neutral targets. Emotional distractors were found to be fixated later and for a shorter duration than emotional targets, suggesting efficient top-down control in avoiding emotional distraction. The fMRI data demonstrated that negative (but not positive) stimuli were mandatorily processed by limbic/para-limbic regions (namely, the right amygdala and the left insula), irrespective of current task relevance: that is, these regions activated for both emotional targets and distractors. However, analyses of inter-regional connectivity revealed a functional coupling between the left insula and the right prefrontal cortex that increased specifically during search in the presence of emotional distractors. This indicates that increased functional coupling between affective limbic/para-limbic regions and control regions in the frontal cortex can attenuate emotional distraction, permitting the allocation of spatial attentional resources toward task-relevant neutral targets in the presence of distracting emotional signals.


Assuntos
Atenção/fisiologia , Emoções/fisiologia , Memória de Curto Prazo/fisiologia , Córtex Pré-Frontal/fisiologia , Acuidade Visual/fisiologia , Adulto , Tonsila do Cerebelo/fisiologia , Mapeamento Encefálico , Córtex Cerebral/fisiologia , Feminino , Lobo Frontal/fisiologia , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Estimulação Luminosa/métodos , Tempo de Reação , Adulto Jovem
20.
Cortex ; 113: 329-346, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30735844

RESUMO

Deficits of visuospatial orienting in brain-damaged patients affected by hemispatial neglect have been extensively investigated. Nonetheless, spontaneous spatial orienting in naturalistic conditions is still poorly understood. Here, we investigated the role played by top-down and stimulus-driven signals in overt spatial orienting of neglect patients during free-viewing of short videos portraying everyday life situations. In Experiment 1, we assessed orienting when meaningful visual events competed on the left and right side of space, and tested whether sensory salience on the two sides biased orienting. In Experiment 2, we examined whether the spatial alignment of visual and auditory signals modulates orienting. The results of Experiment 1 showed that in neglect patients severe deficits in contralesional orienting were restricted to viewing conditions with bilateral visual events competing for attentional capture. In contrast, orienting towards the contralesional side was largely spared when the videos contained a single event on the left side. In neglect patients the processing of stimulus-driven salience was relatively spared and helped orienting towards the left side when multiple events were present. Experiment 2 showed that sounds spatially aligned with visual events on the left side improved orienting towards the otherwise neglected hemispace. Anatomical scans indicated that neglect patients suffered grey and white matter damages primarily in the ventral frontoparietal cortex. This suggests that the improvement of contralesional orienting associated with visual salience and audiovisual spatial alignment may be due to processing in the relatively intact dorsal frontoparietal areas. Our data show that in naturalistic environments, the presence of multiple meaningful events is a major determinant of spatial orienting deficits in neglect patients, whereas the salience of visual signals and the spatial alignment between auditory and visual signals can counteract spatial orienting deficits. These results open new perspectives to develop novel rehabilitation strategies based on the use of naturalistic stimuli.


Assuntos
Movimentos Oculares/fisiologia , Orientação Espacial/fisiologia , Transtornos da Percepção/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Idoso , Atenção/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Transtornos da Percepção/etiologia , Estimulação Luminosa , Acidente Vascular Cerebral/complicações , Percepção Visual/fisiologia
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