240 research outputs found
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Building on a Solid Baseline: Anticipatory Biases in Attention.
A brain-imaging paper by Kastner and colleagues in 1999 was the first to demonstrate that merely focusing attention at a spatial location changed the baseline activity level in various regions of human visual cortex even before any stimuli appeared. The study provided a touchstone for investigating cognitive-sensory interactions and understanding the proactive endogenous signals that shape perception
Orienting Attention Based on Long-Term Memory Improves Perceptual Discriminations
The role of attentional orienting in daily life is to selectively deploy both behavioural and neural resources towards events, based on continually changing task goals and expectations, in order to optimize performance. In the following experiment, we show that attentional orienting is influenced by long-term memories in a perceptual discrimination task. In the learning phase, participants were trained on 120 ecologically valid natural scenes, of which 80 contained a target. Their task was to locate the target (a small key) on the screen by clicking on it with the mouse. One or two days later, participants completed a cued perceptual discrimination task. The same scenes that were studied before, but without any targets, were presented as cues (50 ms duration), followed, after a delay (450ms), by the scene again with or without the target (200ms). Participants discriminated covertly whether the key was present or absent from the second scene. There were three conditions: valid (key in learning and discrimination task was in same location), invalid (key in learning and discrimination task were in different location) and neutral (there was no key in learning phase). Behavioural results indicated that memory-guided attention benefits both the sensitivity (d’) and speed of target identification within natural scenes. A replication of the study is being carried out with event-related potentials to chart the neural modulations that accompany the perceptual enhancements observed behaviourally
The Effect of Retro-Cueing on an ERP Marker of VSTM Maintenance
Previous research has found that Contralateral Delay Activity (CDA) is correlated with the number of items maintained in Visual Short Term Memory from one visual field (VF) (Vogel & Machizawa, 2004). CDA is usually elicited by a to-be-remembered array after a prospective cue (pro-cue) signalling the relevant side of the visual display, and is interpreted as a putative electrophysiological signature of WM maintenance. Attention can also be directed to the contents of VSTM, after the presentation of a visual array, using a retroactive cue (retro-cue) (Nobre, Griffin, & Rao, 2008). Because retro-cueing directs attention within a memory trace, potentially reducing the load of items to be maintained, we hypothesised that this would significantly attenuate the CDA. Participants were initially presented with a spatial pro-cue which reduced the number of to-be-remembered items to one side. After a delay, a memory array of either four (low load) or eight (high load) items was displayed. A retro-cue then cued participants to one location within the relevant VF, further reducing the load of to-be-remembered items; or provided no information, requiring participants to hold all items in the relevant VF. At the end of the trial, participants performed a same/different judgement on a test stimulus. Retro-cues significantly improved VSTM performance. Unexpectedly, the CDA was found to be abolished by the presentation of both spatially predictive and neutral cues, independently of the VSTM load participants had to maintain
Behavioural Dissociation between Exogenous and Endogenous Temporal Orienting of Attention
BACKGROUND: In the current study we compared the effects of temporal orienting of attention based on predictions carried by the intrinsic temporal structure of events (rhythm) and by instructive symbolic cues; and tested the degree of cognitive, strategic control that could be exerted over each type of temporal expectation. The experiments tested whether the distinction between exogenous and endogenous orienting made in spatial attention may extend to the temporal domain. TASK DESIGN AND MAIN RESULTS: In this task, a ball moved across the screen in discrete steps and disappeared temporarily under an occluding band. Participants were required to make a perceptual discrimination on the target upon its reappearance. The regularity of the speed (rhythmic cue) or colour (symbolic cue) of the moving stimulus could predict the exact time at which a target would reappear after a brief occlusion (valid trials) or provide no temporal information (neutral trials). The predictive nature of rhythmic and symbolic cues was manipulated factorially in a symmetrical and orthogonal fashion. To test for the effects of strategic control over temporal orienting based on rhythmic or symbolic cues, participants were instructed either to "attend-to-speed" (rhythm) or "attend-to-colour". Our results indicated that both rhythmic and symbolic (colour) cues speeded reaction times in an independent fashion. However, whilst the rhythmic cueing effects were impervious to instruction, the effects of symbolic cues were contingent on the instruction to attend to colour. FINAL CONCLUSIONS: Taken together, our results provide evidence for the existence of qualitatively separable types of temporal orienting of attention, akin to exogenous and endogenous mechanisms
Magnetoencephalography as a tool in psychiatric research: current status and perspective
The application of neuroimaging to provide mechanistic insights into circuit dysfunctions in major psychiatric conditions and the development of biomarkers are core challenges in current psychiatric research. In this review, we propose that recent technological and analytic advances in Magnetoencephalography (MEG), a technique which allows the measurement of neuronal events directly and non-invasively with millisecond resolution, provides novel opportunities to address these fundamental questions. Because of its potential in delineating normal and abnormal brain dynamics, we propose that MEG provides a crucial tool to advance our understanding of pathophysiological mechanisms of major neuropsychiatric conditions, such as Schizophrenia, Autism Spectrum Disorders, and the dementias. In our paper, we summarize the mechanisms underlying the generation of MEG signals and the tools available to reconstruct generators and underlying networks using advanced source-reconstruction techniques. We then survey recent studies that have utilized MEG to examine aberrant rhythmic activity in neuropsychiatric disorders. This is followed by links with preclinical research, which have highlighted possible neurobiological mechanisms, such as disturbances in excitation/inhibition parameters, which could account for measured changes in neural oscillations. In the final section of the paper, challenges as well as novel methodological developments are discussed which could pave the way for a widespread application of MEG in translational research with the aim of developing biomarkers for early detection and diagnosis
Markers of preparatory attention predict visual short-term memory performance
AbstractVisual short-term memory (VSTM) is limited in capacity. Therefore, it is important to encode only visual information that is most likely to be relevant to behaviour. Here we asked which aspects of selective biasing of VSTM encoding predict subsequent memory-based performance. We measured EEG during a selective VSTM encoding task, in which we varied parametrically the memory load and the precision of recall required to compare a remembered item to a subsequent probe item. On half the trials, a spatial cue indicated that participants only needed to encode items from one hemifield. We observed a typical sequence of markers of anticipatory spatial attention: early attention directing negativity (EDAN), anterior attention directing negativity (ADAN), late directing attention positivity (LDAP); as well as of VSTM maintenance: contralateral delay activity (CDA). We found that individual differences in preparatory brain activity (EDAN/ADAN) predicted cue-related changes in recall accuracy, indexed by memory-probe discrimination sensitivity (d′). Importantly, our parametric manipulation of memory-probe similarity also allowed us to model the behavioural data for each participant, providing estimates for the quality of the memory representation and the probability that an item could be retrieved. We found that selective encoding primarily increased the probability of accurate memory recall; that ERP markers of preparatory attention predicted the cue-related changes in recall probability
Chapter 4 : “Japanese-English Contrasts of Evidentiality and its Applicability to language education”
Orienting attention retrospectively to selective contents in working memory (WM) influences performance. A separate line of research has shown that stimulus strength shapes perceptual representations. There is little research on how stimulus strength during encoding shapes WM performance, and how effects of retrospective orienting might vary with changes in stimulus strength. We explore these questions in three experiments using a continuous-recall WM task. In Experiment 1 we show that benefits of cueing spatial attention retrospectively during WM maintenance (retrocueing) varies according to stimulus contrast during encoding. Retrocueing effects emerge for supraliminal but not sub-threshold stimuli. However, once stimuli are supraliminal, performance is no longer influenced by stimulus contrast. In Experiments 2 and 3 we used a mixture-model approach to examine how different sources of error in WM are affected by contrast and retrocueing. For high-contrast stimuli (Experiment 2), retrocues increased the precision of successfully remembered items. For low-contrast stimuli (Experiment 3), retrocues decreased the probability of mistaking a target with distracters. These results suggest that the processes by which retrospective attentional orienting shape WM performance are dependent on the quality of WM representations, which in turn depends on stimulus strength during encoding
The GLM-spectrum:A multilevel framework for spectrum analysis with covariate and confound modelling
The frequency spectrum is a central method for representing the dynamics within electrophysiological data. Some widely used spectrum estimators make use of averaging across time segments to reduce noise in the final spectrum. The core of this approach has not changed substantially since the 1960s, though many advances in the field of regression modelling and statistics have been made during this time. Here, we propose a new approach, the General Linear Model (GLM) Spectrum, which reframes time averaged spectral estimation as multiple regression. This brings several benefits, including the ability to do confound modelling, hierarchical modelling, and significance testing via non-parametric statistics. We apply the approach to a dataset of EEG recordings of participants who alternate between eyes-open and eyes-closed resting state. The GLM-Spectrum can model both conditions, quantify their differences, and perform denoising through confound regression in a single step. This application is scaled up from a single channel to a whole head recording and, finally, applied to quantify age differences across a large group-level dataset. We show that the GLM-Spectrum lends itself to rigorous modelling of within- and between-subject contrasts as well as their interactions, and that the use of model-projected spectra provides an intuitive visualisation. The GLM-Spectrum is a flexible framework for robust multilevel analysis of power spectra, with adaptive covariate and confound modelling
Using XR (extended reality) for behavioral, clinical, and learning sciences requires updates in infrastructure and funding
Extended reality (XR, including Augmented and Virtual Reality) creates a powerful
intersection between information technology and cognitive, clinical, and education
sciences. XR technology has long captured the public imagination, and its development is
the focus of major technology companies. This article demonstrates the potential of XR to
(1) deliver behavioral insights, (2) transform clinical treatments, and (3) improve learning
and education. However, without appropriate policy, funding, and infrastructural
investment, many research institutions will struggle to keep pace with the advances and
opportunities of XR. To realize the full potential of XR for basic and translational research,
funding should incentivize (1) appropriate training, (2) open software solutions, and (3)
collaborations between complementary academic and industry partners. Bolstering the XR
research infrastructure with the right investments and incentives is vital for delivering on
the potential for transformative discoveries, innovations, and applications
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