Publications by authors named "Anna C Nobre"

139 Publications

Decoding visual colour from scalp electroencephalography measurements.

Neuroimage 2021 Apr 6:118030. Epub 2021 Apr 6.

Department of Experimental Psychology, University of Oxford, Oxford, UK.

Recent advances have made it possible to decode various aspects of visually presented stimuli from patterns of scalp EEG measurements. As of recently, such multivariate methods have been commonly used to decode visual-spatial features such as location, orientation, or spatial frequency. In the current proof-of-principle study, we show that it is also possible to track visual colour processing by using Linear Discriminant Analysis. Building on other recent demonstrations, we show that colour decoding: (1) reflects sensory qualities (as opposed to, for example, verbal labelling) with a prominent contribution from posterior electrodes contralateral to the stimulus, (2) conforms to a parametric coding space, (3) is possible in multi-item displays, and (4) is comparable in magnitude to the decoding of visual stimulus orientation. Through subsampling our data, we also provide an estimate of the approximate number of trials and participants required for robust decoding. Colour decoding opens a relevant new dimension in which to track visual processing using scalp EEG measurements, while bypassing potential confounds associated with decoding approaches that focus on spatial features.
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http://dx.doi.org/10.1016/j.neuroimage.2021.118030DOI Listing
April 2021

Output planning at the input stage in visual working memory.

Sci Adv 2021 Mar 24;7(13). Epub 2021 Mar 24.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK.

Working memory serves as the buffer between past sensations and future behavior, making it vital to understand not only how we encode and retain sensory information in memory but also how we plan for its upcoming use. We ask when prospective action goals emerge alongside the encoding and retention of visual information in working memory. We show that prospective action plans do not emerge gradually during memory delays but are brought into memory early, in tandem with sensory encoding. This action encoding (i) precedes a second stage of action preparation that adapts to the time of expected memory utilization, (ii) occurs even ahead of an intervening motor task, and (iii) predicts visual memory-guided behavior several seconds later. By bringing prospective action plans into working memory at an early stage, the brain creates a dual (visual-motor) memory code that can make memories more effective and robust for serving ensuing behavior.
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http://dx.doi.org/10.1126/sciadv.abe8212DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7990334PMC
March 2021

Functional biases in attentional templates from associative memory.

J Vis 2020 12;20(13)

Department of Experimental Psychology, University of Oxford, Oxford, UK.

In everyday life, attentional templates-which facilitate the perception of task-relevant sensory inputs-are often based on associations in long-term memory. We ask whether templates retrieved from memory are necessarily faithful reproductions of the encoded information or if associative-memory templates can be functionally adapted after retrieval in service of current task demands. Participants learned associations between four shapes and four colored gratings, each with a characteristic combination of color (green or pink) and orientation (left or right tilt). On each trial, observers saw one shape followed by a grating and indicated whether the pair matched the learned shape-grating association. Across experimental blocks, we manipulated the types of nonmatch (lure) gratings most often presented. In some blocks the lures were most likely to differ in color but not tilt, whereas in other blocks this was reversed. If participants functionally adapt the retrieved template such that the distinguishing information between lures and targets is prioritized, then they should overemphasize the most commonly diagnostic feature dimension within the template. We found evidence for this in the behavioral responses to the lures: participants were more accurate and faster when responding to common versus rare lures, as predicted by the functional-but not the strictly veridical-template hypothesis. This shows that templates retrieved from memory can be functionally biased to optimize task performance in a flexible, context-dependent, manner.
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http://dx.doi.org/10.1167/jov.20.13.7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7729124PMC
December 2020

When Natural Behavior Engages Working Memory.

Curr Biol 2021 Feb 4;31(4):869-874.e5. Epub 2020 Dec 4.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford OX3 7JX, UK; Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK.

Working memory (WM) enables temporary storage and manipulation of information, supporting tasks that require bridging between perception and subsequent behavior. Its properties, such as its capacity, have been thoroughly investigated in highly controlled laboratory tasks. Much less is known about the utilization and properties of WM in natural behavior, when reliance on WM emerges as a natural consequence of interactions with the environment. We measured the trade-off between reliance on WM and gathering information externally during immersive behavior in an adapted object-copying task. By manipulating the locomotive demands required for task completion, we could investigate whether and how WM utilization changed as gathering information from the environment became more effortful. Reliance on WM was lower than WM capacity measures in typical laboratory tasks. A clear trade-off also occurred. As sampling information from the environment required increasing locomotion and time investment, participants relied more on their WM representations. This reliance on WM increased in a shallow and linear fashion and was associated with longer encoding durations. Participants' avoidance of WM usage showcases a fundamental dependence on external information during ecological behavior, even if the potentially storable information is well within the capacity of the cognitive system. These foundational findings highlight the importance of using immersive tasks to understand how cognitive processes unfold within natural behavior. Our novel VR approach effectively combines the ecological validity, experimental rigor, and sensitive measures required to investigate the interplay between memory and perception in immersive behavior. VIDEO ABSTRACT.
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http://dx.doi.org/10.1016/j.cub.2020.11.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7902904PMC
February 2021

Goal-directed and stimulus-driven selection of internal representations.

Proc Natl Acad Sci U S A 2020 09 14;117(39):24590-24598. Epub 2020 Sep 14.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford OX3 7JX, United Kingdom.

Adaptive behavior relies on the selection of relevant sensory information from both the external environment and internal memory representations. In understanding external selection, a classic distinction is made between voluntary (goal-directed) and involuntary (stimulus-driven) guidance of attention. We have developed a task-the anti-retrocue task-to separate and examine voluntary and involuntary guidance of attention to internal representations in visual working memory. We show that both voluntary and involuntary factors influence memory performance but do so in distinct ways. Moreover, by tracking gaze biases linked to attentional focusing in memory, we provide direct evidence for an involuntary "retro-capture" effect whereby external stimuli involuntarily trigger the selection of feature-matching internal representations. We show that stimulus-driven and goal-directed influences compete for selection in memory, and that the balance of this competition-as reflected in oculomotor signatures of internal attention-predicts the quality of ensuing memory-guided behavior. Thus, goal-directed and stimulus-driven factors together determine the fate not only of perception, but also of internal representations in working memory.
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http://dx.doi.org/10.1073/pnas.2013432117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7533705PMC
September 2020

Purpose-Dependent Consequences of Temporal Expectations Serving Perception and Action.

J Neurosci 2020 10 8;40(41):7877-7886. Epub 2020 Sep 8.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford OX3 7JX, United Kingdom.

Temporal expectations enable anticipatory brain states that prepare us for upcoming perception and action. We investigated the purpose-dependent nature and consequences of cued temporal expectations on brain and behavior in male and female human volunteers, using two matched visual-motor tasks that stressed either response speed or visual accuracy. We show that the consequences of temporal expectations are fundamentally purpose dependent. Temporal expectations predominantly affected response times when visual demands were low and speed was more important, but perceptual accuracy when visual demands were more challenging. Using magnetoencephalography, we further show how temporal expectations latch onto anticipatory neural states associated with concurrent spatial expectations-modulating task-specific anticipatory neural lateralization of oscillatory brain activity in a modality- and frequency-specific manner. By relating these brain states to behavior, we finally reveal how the behavioral relevance of such anticipatory brain states is similarly purpose dependent. Knowing when events may occur helps to prepare neural activity for upcoming perception and action. It is becoming increasingly clear that distinct sources of temporal expectations may facilitate performance via distinct mechanisms. Another relevant dimension to consider regards the distinct purposes that temporal expectations may serve. Here, we demonstrate that the consequences of temporal expectations on neurophysiological brain activity and behavior are fundamentally purpose dependent, and show how temporal expectations interact with task-relevant neural states in a modality- and frequency-specific manner. This brings the important insight that the ways in which temporal expectations influence brain and behavior, and how brain activity is related to behavior, are not fixed properties but rather depend on the task at hand.
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http://dx.doi.org/10.1523/JNEUROSCI.1134-20.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7548698PMC
October 2020

Temporal Expectations Prepare Visual Working Memory for Behavior.

J Cogn Neurosci 2020 12 8;32(12):2320-2332. Epub 2020 Sep 8.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging.

Working memory enables us to retain past sensations in service of anticipated task demands. How we prepare for anticipated task demands during working memory retention remains poorly understood. Here, we focused on the role of time-asking how temporal expectations help prepare for ensuing memory-guided behavior. We manipulated the expected probe time in a delayed change-detection task and report that temporal expectation can have a profound influence on memory-guided behavioral performance. EEG measurements corroborated the utilization of temporal expectations: demonstrating the involvement of a classic EEG signature of temporal expectation-the contingent negative variation-in the context of working memory. We also report the influence of temporal expectations on 2 EEG signatures associated with visual working memory-the lateralization of 8- to 12-Hz alpha activity, and the contralateral delay activity. We observed a dissociation between these signatures, whereby alpha lateralization (but not the contralateral delay activity) adapted to the time of expected memory utilization. These data show how temporal expectations prepare visual working memory for behavior and shed new light on the electrophysiological markers of both temporal expectation and working memory.
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http://dx.doi.org/10.1162/jocn_a_01626DOI Listing
December 2020

Comparing the prioritization of items and feature-dimensions in visual working memory.

J Vis 2020 08;20(8):25

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, UK.

Selective attention can be directed not only to external sensory inputs, but also to internal sensory representations held within visual working memory (VWM). To date, this phenomenon has been studied predominantly following retrospective cues directing attention to particular items, or their locations in memory. In addition to item-level attentional prioritization, recent studies have shown that selectively attending to feature dimensions in VWM can also improve memory recall performance. However, no study to date has directly compared item-based and dimension-based attention in VWM, nor their neural bases. Here, we compared the benefits of retrospective cues (retro-cues) that were directed either at a multifeature item or at a feature dimension that was shared between two spatially segregated items. Behavioral results revealed qualitatively similar attentional benefits in both recall accuracy and response time, but also showed that cueing benefits were larger after item cues. Concurrent electroencephalogram measurements further revealed a similar attenuation of posterior alpha oscillations following both item and dimension retro-cues when compared with noninformative, neutral retro-cues. We argue that attention can act flexibly to prioritize the most relevant information-at either the item or the dimension level-to optimize ensuing memory-based task performance, and we discuss the implications of the observed commonalities and differences between item-level and dimension-level prioritization in VWM.
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http://dx.doi.org/10.1167/jov.20.8.25DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7453048PMC
August 2020

Synchronisation of Neural Oscillations and Cross-modal Influences.

Trends Cogn Sci 2020 06 18;24(6):481-495. Epub 2020 Apr 18.

Department of Experimental Psychology, Brain and Cognition Lab, Oxford Centre for Human Brain Activity, Department of Psychiatry, Wellcome Centre for Integrative Neuroimaging, University of Oxford, UK.

At any given moment, we receive multiple signals from our different senses. Prior research has shown that signals in one sensory modality can influence neural activity and behavioural performance associated with another sensory modality. Recent human and nonhuman primate studies suggest that such cross-modal influences in sensory cortices are mediated by the synchronisation of ongoing neural oscillations. In this review, we consider two mechanisms proposed to facilitate cross-modal influences on sensory processing, namely cross-modal phase resetting and neural entrainment. We consider how top-down processes may further influence cross-modal processing in a flexible manner, and we highlight fruitful directions for further research.
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http://dx.doi.org/10.1016/j.tics.2020.03.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7653674PMC
June 2020

One Thing Leads to Another: Anticipating Visual Object Identity Based on Associative-Memory Templates.

J Neurosci 2020 05 13;40(20):4010-4020. Epub 2020 Apr 13.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford OX3 7JX, United Kingdom.

Probabilistic associations between stimuli afford memory templates that guide perception through proactive anticipatory mechanisms. A great deal of work has examined the behavioral consequences and human electrophysiological substrates of anticipation following probabilistic memory cues that carry spatial or temporal information to guide perception. However, less is understood about the electrophysiological substrates linked to anticipating the sensory content of events based on recurring associations between successive events. Here, we demonstrate behavioral and electrophysiological signatures of using associative-memory templates to guide perception, while equating spatial and temporal anticipation (experiments 1 and 2), as well as target probability and response demands (experiment 2). By recording the electroencephalogram in the two experiments ( = 55; 24 females), we show that two markers in human electrophysiology implicated in spatial and temporal anticipation also contribute to the anticipation of perceptual identity, as follows: attenuation of alpha-band oscillations and the contingent negative variation (CNV). Together, our results show that memory-guided identity templates proactively impact perception and are associated with anticipatory states of attenuated alpha oscillations and the CNV. Furthermore, by isolating object-identity anticipation from spatial and temporal anticipation, our results suggest a role for alpha attenuation and the CNV in specific visual content anticipation beyond general changes in neural excitability or readiness. Probabilistic associations between stimuli afford memory templates that guide perception through proactive anticipatory mechanisms. The current work isolates the behavioral benefits and electrophysiological signatures of memory-guided identity-based anticipation, while equating anticipation of space, time, motor responses, and task relevance. Our results show that anticipation of the specific identity of a forthcoming percept impacts performance and is associated with states of attenuated alpha oscillations and the contingent negative variation, extending previous work implicating these neural substrates in spatial and temporal preparatory attention. Together, this work bridges fields of attention, memory, and perception, providing new insights into the neural mechanisms that support complex attentional templates.
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http://dx.doi.org/10.1523/JNEUROSCI.2751-19.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7219293PMC
May 2020

Dissecting beta-state changes during timed movement preparation in Parkinson's disease.

Prog Neurobiol 2020 01 25;184:101731. Epub 2019 Nov 25.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, United Kingdom; Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom. Electronic address:

An emerging perspective describes beta-band (15-28 Hz) activity as consisting of short-lived high-amplitude events that only appear sustained in conventional measures of trial-average power. This has important implications for characterising abnormalities observed in beta-band activity in disorders like Parkinson's disease. Measuring parameters associated with beta-event dynamics may yield more sensitive measures, provide more selective diagnostic neural markers, and provide greater mechanistic insight into the breakdown of brain dynamics in this disease. Here, we used magnetoencephalography in eighteen Parkinson's disease participants off dopaminergic medication and eighteen healthy control participants to investigate beta-event dynamics during timed movement preparation. We used the Hidden Markov Model to classify event dynamics in a data-driven manner and derived three parameters of beta events: (1) beta-state amplitude, (2) beta-state lifetime, and (3) beta-state interval time. Of these, changes in beta-state interval time explained the overall decreases in beta power during timed movement preparation and uniquely captured the impairment in such preparation in patients with Parkinson's disease. Thus, the increased granularity of the Hidden Markov Model analysis (compared with conventional analysis of power) provides increased sensitivity and suggests a possible reason for impairments of timed movement preparation in Parkinson's disease.
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http://dx.doi.org/10.1016/j.pneurobio.2019.101731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6977086PMC
January 2020

Unpacking Transient Event Dynamics in Electrophysiological Power Spectra.

Brain Topogr 2019 11 21;32(6):1020-1034. Epub 2019 Nov 21.

Department of Psychiatry, Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK.

Electrophysiological recordings of neuronal activity show spontaneous and task-dependent changes in their frequency-domain power spectra. These changes are conventionally interpreted as modulations in the amplitude of underlying oscillations. However, this overlooks the possibility of underlying transient spectral 'bursts' or events whose dynamics can map to changes in trial-average spectral power in numerous ways. Under this emerging perspective, a key challenge is to perform burst detection, i.e. to characterise single-trial transient spectral events, in a principled manner. Here, we describe how transient spectral events can be operationalised and estimated using Hidden Markov Models (HMMs). The HMM overcomes a number of the limitations of the standard amplitude-thresholding approach to burst detection; in that it is able to concurrently detect different types of bursts, each with distinct spectral content, without the need to predefine frequency bands of interest, and does so with less dependence on a priori threshold specification. We describe how the HMM can be used for burst detection and illustrate its benefits on simulated data. Finally, we apply this method to empirical data to detect multiple burst types in a task-MEG dataset, and illustrate how we can compute burst metrics, such as the task-evoked timecourse of burst duration.
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http://dx.doi.org/10.1007/s10548-019-00745-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6882750PMC
November 2019

Rhythmic Temporal Expectation Boosts Neural Activity by Increasing Neural Gain.

J Neurosci 2019 12 29;39(49):9806-9817. Epub 2019 Oct 29.

Department of Experimental Psychology, University of Oxford, Oxford OX2 6GG, United Kingdom, and.

Temporal orienting improves sensory processing, akin to other top-down biases. However, it is unknown whether these improvements reflect increased neural gain to any stimuli presented at expected time points, or specific tuning to task-relevant stimulus aspects. Furthermore, while other top-down biases are selective, the extent of trade-offs across time is less well characterized. Here, we tested whether gain and/or tuning of auditory frequency processing in humans is modulated by rhythmic temporal expectations, and whether these modulations are specific to time points relevant for task performance. Healthy participants ( = 23) of either sex performed an auditory discrimination task while their brain activity was measured using magnetoencephalography/electroencephalography (M/EEG). Acoustic stimulation consisted of sequences of brief distractors interspersed with targets, presented in a rhythmic or jittered way. Target rhythmicity not only improved behavioral discrimination accuracy and M/EEG-based decoding of targets, but also of irrelevant distractors preceding these targets. To explain this finding in terms of increased sensitivity and/or sharpened tuning to auditory frequency, we estimated tuning curves based on M/EEG decoding results, with separate parameters describing gain and sharpness. The effect of rhythmic expectation on distractor decoding was linked to gain increase only, suggesting increased neural sensitivity to any stimuli presented at relevant time points. Being able to predict when an event may happen can improve perception and action related to this event, likely due to the alignment of neural activity to the temporal structure of stimulus streams. However, it is unclear whether rhythmic increases in neural sensitivity are specific to task-relevant targets, and whether they competitively impair stimulus processing at unexpected time points. By combining magnetoencephalography and encephalographic recordings, neural decoding of auditory stimulus features, and modeling, we found that rhythmic expectation improved neural decoding of both relevant targets and irrelevant distractors presented and expected time points, but did not competitively impair stimulus processing at unexpected time points. Using a quantitative model, these results were linked to nonspecific neural gain increases due to rhythmic expectation.
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http://dx.doi.org/10.1523/JNEUROSCI.0925-19.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6891052PMC
December 2019

Modulation of the pupillary response by the content of visual working memory.

Proc Natl Acad Sci U S A 2019 11 21;116(45):22802-22810. Epub 2019 Oct 21.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, OX3 7JX Oxford, United Kingdom.

Studies of selective attention during perception have revealed modulation of the pupillary response according to the brightness of task-relevant (attended) vs. -irrelevant (unattended) stimuli within a visual display. As a strong test of top-down modulation of the pupil response by selective attention, we asked whether changes in pupil diameter follow internal shifts of attention to memoranda of visual stimuli of different brightness maintained in working memory, in the absence of any visual stimulation. Across 3 studies, we reveal dilation of the pupil when participants orient attention to the memorandum of a dark grating relative to that of a bright grating. The effect occurs even when the attention-orienting cue is independent of stimulus brightness, and even when stimulus brightness is merely incidental and not required for the working-memory task of judging stimulus orientation. Furthermore, relative dilation and constriction of the pupil occurred dynamically and followed the changing temporal expectation that 1 or the other stimulus would be probed across the retention delay. The results provide surprising and consistent evidence that pupil responses are under top-down control by cognitive factors, even when there is no direct adaptive gain for such modulation, since no visual stimuli were presented or anticipated. The results also strengthen the view of sensory recruitment during working memory, suggesting even activation of sensory receptors. The thought-provoking corollary to our findings is that the pupils provide a reliable measure of what is in the focus of mind, thus giving a different meaning to old proverbs about the eyes being a window to the mind.
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http://dx.doi.org/10.1073/pnas.1909959116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6842592PMC
November 2019

Premembering Experience: A Hierarchy of Time-Scales for Proactive Attention.

Neuron 2019 10;104(1):132-146

Department of Experimental Psychology, University of Oxford, Oxford, UK; Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK.

Memories are about the past, but they serve the future. Memory research often emphasizes the former aspect: focusing on the functions that re-constitute (re-member) experience and elucidating the various types of memories and their interrelations, timescales, and neural bases. Here we highlight the prospective nature of memory in guiding selective attention, focusing on functions that use previous experience to anticipate the relevant events about to unfold-to "premember" experience. Memories of various types and timescales play a fundamental role in guiding perception and performance adaptively, proactively, and dynamically. Consonant with this perspective, memories are often recorded according to expected future demands. Using working memory as an example, we consider how mnemonic content is selected and represented for future use. This perspective moves away from the traditional representational account of memory toward a functional account in which forward-looking memory traces are informationally and computationally tuned for interacting with incoming sensory signals to guide adaptive behavior.
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http://dx.doi.org/10.1016/j.neuron.2019.08.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6873797PMC
October 2019

Biomagnetic biomarkers for dementia: A pilot multicentre study with a recommended methodological framework for magnetoencephalography.

Alzheimers Dement (Amst) 2019 Dec 14;11:450-462. Epub 2019 Jun 14.

Laboratory of Cognitive and Computational Neuroscience (UCM-UPM), Centre for Biomedical Technology, Madrid, Spain.

Introduction: An increasing number of studies are using magnetoencephalography (MEG) to study dementia. Here we define a common methodological framework for MEG resting-state acquisition and analysis to facilitate the pooling of data from different sites.

Methods: Two groups of patients with mild cognitive impairment (MCI, n = 84) and healthy controls (n = 84) were combined from three sites, and site and group differences inspected in terms of power spectra and functional connectivity. Classification accuracy for MCI versus controls was compared across three different types of MEG analyses, and compared with classification based on structural MRI.

Results: The spectral analyses confirmed frequency-specific differences in patients with MCI, both in power and connectivity patterns, with highest classification accuracy from connectivity. Critically, site acquisition differences did not dominate the results.

Discussion: This work provides detailed protocols and analyses that are sensitive to cognitive impairment, and that will enable standardized data sharing to facilitate large-scale collaborative projects.
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http://dx.doi.org/10.1016/j.dadm.2019.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6579903PMC
December 2019

Dynamic sustained attention markers differentiate atypical development: The case of Williams syndrome and Down's syndrome.

Neuropsychologia 2019 09 16;132:107148. Epub 2019 Jul 16.

Department of Experimental Psychology, University of Oxford, United Kingdom. Electronic address:

Impaired sustained attention is considered an important factor in determining poor functional outcomes across multiple cognitive and behavioural disorders. Sustained attention is compromised for both children with Williams syndrome (WS) and Down's syndrome (DS), but specific difficulties remain poorly understood because of limitations in how sustained attention has been assessed thus far. In the current study, we compared the performance of typically developing children (N = 99), children with WS (N = 25), and children with DS (N = 18), on a Continuous Performance Task - a standard tool for measuring sustained attention. In contrast to previous studies, primarily focused on overall differences in mean performance, we estimated the extent to which performance changed over time on task, thus focusing directly on the sustained element of performance. Children with WS and children with DS performed more poorly overall compared to typically developing children. Importantly, measures specific to changes over time differentiated between children with the two syndromes. Children with WS showed a decrement in performance, whereas children with Down's syndrome demonstrated non-specific poor performance. In addition, our measure of change in performance predicted teacher-rated attention deficits symptoms across the full sample. An approach that captures dynamic changes in performance over assessments may be fruitful for investigating similarities and differences in sustained attention for other atypically developing populations.
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http://dx.doi.org/10.1016/j.neuropsychologia.2019.107148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6891877PMC
September 2019

The tempos of performance.

Curr Opin Psychol 2019 10 18;29:254-260. Epub 2019 Jun 18.

Department of Experimental Psychology, Oxford Centre for Human Brain Activity, Department of Psychiatry, and Wellcome Centre for Integrative Neuroimaging, University of Oxford, United Kingdom.

Human performance fluctuates over time. Rather than random, the complex time course of variation reflects, among other factors, influences from regular periodic processes operating at multiple time scales. In this review, we consider evidence for how our performance ebbs and flows over fractions of seconds as we engage with sensory objects, over minutes as we perform tasks, and over hours according to homeostatic factors. We propose that rhythms of performance at these multiple tempos arise from the interplay among three sources of influence: intrinsic fluctuations in brain activity, periodicity of external stimulation, and the anticipation of the temporal structure of external stimulation by the brain.
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http://dx.doi.org/10.1016/j.copsyc.2019.06.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6996131PMC
October 2019

Dissociable Catecholaminergic Modulation of Visual Attention: Differential Effects of Catechol-O-Methyltransferase and Dopamine Beta-Hydroxylase Genes on Visual Attention.

Neuroscience 2019 08 10;412:175-189. Epub 2019 Jun 10.

Department of Experimental Psychology, University of Oxford, Oxford, UK; Centre for Human Brain Health, University of Birmingham, Birmingham, UK; School of Psychology, University of Birmingham, Birmingham, UK; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, USA. Electronic address:

Visual attention enables us to prioritise behaviourally relevant visual information while ignoring distraction. The neural networks supporting attention are modulated by two catecholamines, dopamine and noradrenaline. The current study investigated the effects of single nucleotide polymorphisms in two catecholaminergic genes - COMT (ValMet) and DBH (444 G/A) - on individual differences in attention functions. Participants (n = 125) were recruited from the Oxford Biobank by genotype-based recall. They were tested on a continuous performance task (sustained attention), a Go/No-Go task (response inhibition), and a task assessing attentional selection in accordance with the Theory of Visual Attention (TVA). We found a significant effect of DBH genotype status on the capacity to maintain attention over time (sustained attention) as measured by the continuous performance task. Furthermore, we demonstrated a significant association between COMT genotype status and effective threshold of visual perception in attentional selection as estimated based on the TVA task performance. No other group differences in attention function were found with respect to the studied genotypes. Overall, our findings provide novel experimental evidence that: (i) dopaminergic and noradrenergic genotypes have dissociable effects on visual attention; (ii) either insufficient or excessive catecholaminergic activity may have equally detrimental effects on sustained attention.
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http://dx.doi.org/10.1016/j.neuroscience.2019.05.068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6645579PMC
August 2019

Introduction.

Authors:
Anna C Nobre

Neuropsychologia 2019 05;128

Department of Experimental Psychology and Oxford Centre for Human Brain Activity, Department of Psychiatry, Wellcome Centre for Integrative Neuroimaging, University of Oxford, United Kingdom.

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http://dx.doi.org/10.1016/j.neuropsychologia.2018.08.011DOI Listing
May 2019

Human gaze tracks attentional focusing in memorized visual space.

Nat Hum Behav 2019 05 4;3(5):462-470. Epub 2019 Mar 4.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK.

Brain areas that control gaze are also recruited for covert shifts of spatial attention. In the external space of perception, there is a natural ecological link between the control of gaze and spatial attention, as information sampled at covertly attended locations can inform where to look next. Attention can also be directed internally to representations held within the spatial layout of visual working memory. In such cases, the incentive for using attention to direct gaze disappears, as there are no external targets to scan. Here we investigate whether the oculomotor system of the brain also participates in attention focusing within the internal space of memory. Paradoxically, we reveal this participation through gaze behaviour itself. We demonstrate that selecting an item from visual working memory biases gaze in the direction of the memorized location of that item, despite there being nothing to look at and location memory never explicitly being probed. This retrospective 'gaze bias' occurs only when an item is not already in the internal focus of attention, and it predicts the performance benefit associated with the focusing of internal attention. We conclude that the oculomotor system also participates in focusing attention within memorized space, leaving traces all the way to the eyes.
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http://dx.doi.org/10.1038/s41562-019-0549-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6546593PMC
May 2019

Neural markers of category-based selective working memory in aging.

Neuroimage 2019 07 21;194:163-173. Epub 2019 Mar 21.

Department of Experimental Psychology, University of Oxford, UK; Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, UK. Electronic address:

Working memory (WM) is essential for normal cognitive function, but shows marked decline in aging. The importance of selective attention in guiding WM performance is increasingly recognized. Studies so far are inconclusive about the ability to use selective attention during WM in aging. To investigate the neural mechanisms supporting selective attention in WM in aging, we tested a large group of older adults using functional magnetic resonance imaging whilst they performed a category-based (faces/houses) selective-WM task. Older adults were able to use attention to encode targets and suppress distractors to reach high levels of task performance. A subsequent, surprise recognition-memory task showed strong consequences of selective attention. Attended items in the relevant category were recognized significantly better than items in the ignored category. Neural measures also showed reliable markers of selective attention during WM. Purported control regions including the dorsolateral and inferior prefrontal and anterior cingulate cortex were reliably recruited for attention to both categories. Activation levels in category-sensitive visual cortex showed reliable modulation according to attentional demands, and positively correlated with subsequent memory measures of attention and WM span. Psychophysiological interaction analyses showed that activity in category-sensitive areas were coupled with non-sensory cortex known to be involved in cognitive control and memory processing, including regions in the prefrontal cortex and hippocampus. In summary, we found that older adults were able to recruit a network of brain regions involved in top-down attention during selective WM, and individual differences in attentional control corresponded to the degree of attention-related modulation in the brain.
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http://dx.doi.org/10.1016/j.neuroimage.2019.03.033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6547047PMC
July 2019

Time for What? Breaking Down Temporal Anticipation.

Trends Neurosci 2019 06 15;42(6):373-374. Epub 2019 Mar 15.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, UK. Electronic address:

A variety of environmental regularities enable us to anticipate the timing of upcoming sensations and actions. A recent article (Breska and Ivry, Proc. Natl. Acad. Sci. U. S. A. 2018;115:12283-12288) reports a striking neural double dissociation between two distinct varieties of temporal anticipation. Looking forward, we consider further dissociations according to the goals for which temporal anticipation is used.
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http://dx.doi.org/10.1016/j.tins.2019.03.002DOI Listing
June 2019

Punishment-related memory-guided attention: Neural dynamics of perceptual modulation.

Cortex 2019 06 10;115:231-245. Epub 2019 Feb 10.

Department of Clinical Psychology and Psychobiology, University of Santiago de Compostela, Santiago de Compostela, Spain. Electronic address:

Remembering the outcomes of past experiences allows us to generate future expectations and shape selection in the long-term. A growing number of studies has shown that learned positive reward values impact spatial memory-based attentional biases on perception. However, whether memory-driven attentional biases extend to punishment-related values has received comparatively less attention. Here, we manipulated whether recent spatial contextual memories became associated with successful avoidance of punishment (potential monetary loss). Behavioral and electrophysiological measures were collected from 27 participants during a subsequent memory-based attention task, in which we tested for the effect of punishment avoidance associations. Punishment avoidance significantly amplified effects of spatial contextual memories on visual search processes within natural scenes. Compared to non-associated scenes, contextual memories paired with punishment avoidance lead to faster responses to targets presented at remembered locations. Event-related potentials elicited by target stimuli revealed that acquired motivational value of specific spatial locations, by virtue of their association with past avoidance of punishment, dynamically affected neural signatures of early visual processing (indexed by larger P1 and earlier N1 potentials) and target selection (as indicated by reduced N2pc potentials). The present results extend our understanding of how memory, attention, and punishment-related mechanisms interact to optimize perceptual decision in real world environments.
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http://dx.doi.org/10.1016/j.cortex.2019.01.029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6525146PMC
June 2019

The Oxford study of Calcium channel Antagonism, Cognition, Mood instability and Sleep (OxCaMS): study protocol for a randomised controlled, experimental medicine study.

Trials 2019 Feb 12;20(1):120. Epub 2019 Feb 12.

Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, OX3 7JX, UK.

Background: The discovery that voltage-gated calcium channel genes such as CACNA1C are part of the aetiology of psychiatric disorders has rekindled interest in the therapeutic potential of L-type calcium channel (LTCC) antagonists. These drugs, licensed to treat hypertension and angina, have previously been used in bipolar disorder, but without clear results. Neither is much known about the broader effects of these drugs on the brain and behaviour.

Methods: The Oxford study of Calcium channel Antagonism, Cognition, Mood instability and Sleep (OxCaMS) is a high-intensity randomised, double-blind, placebo-controlled experimental medicine study on the effect of the LTCC antagonist nicardipine in healthy young adults with mood instability. An array of cognitive, psychiatric, circadian, physiological, biochemical and neuroimaging (functional magnetic resonance imaging and magnetoencephalography) parameters are measured during a 4-week period, with randomisation to drug or placebo on day 14. We are interested in whether nicardipine affects the stability of these measures, as well as its overall effects. Participants are genotyped for the CACNA1C risk polymorphism rs1006737.

Discussion: The results will clarify the potential of LTCC antagonists for repurposing or modification for use in psychiatric disorders in which cognition, mood and sleep are affected.

Trial Registration: ISRCTN, ISRCTN33631053 . Retrospectively registered on 8 June 2018 (applied 17 May 2018).
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http://dx.doi.org/10.1186/s13063-019-3175-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6373140PMC
February 2019

Concurrent visual and motor selection during visual working memory guided action.

Nat Neurosci 2019 03 4;22(3):477-483. Epub 2019 Feb 4.

Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK.

Visual working memory enables us to hold onto past sensations in anticipation that these may become relevant for guiding future actions. Yet laboratory tasks have treated visual working memories in isolation from their prospective actions and have focused on the mechanisms of memory retention rather than utilization. To understand how visual memories become used for action, we linked individual memory items to particular actions and independently tracked the neural dynamics of visual and motor selection when memories became used for action. This revealed concurrent visual-motor selection, engaging appropriate visual and motor brain areas at the same time. Thus we show that items in visual working memory can invoke multiple, item-specific, action plans that can be accessed together with the visual representations that guide them, affording fast and precise memory-guided behavior.
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http://dx.doi.org/10.1038/s41593-018-0335-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6420070PMC
March 2019

Temporally Unconstrained Decoding Reveals Consistent but Time-Varying Stages of Stimulus Processing.

Cereb Cortex 2019 02;29(2):863-874

Department of Psychiatry, Oxford Centre for Human Brain Activity (OHBA), University of Oxford, Oxford, UK.

In this article, we propose a method to track trial-specific neural dynamics of stimulus processing and decision making with high temporal precision. By applying this novel method to a perceptual template-matching task, we tracked representational brain states associated with the cascade of neural processing, from early sensory areas to higher order areas that are involved in integration and decision making. We address a major limitation of the traditional decoding approach: that it relies on consistent timing of these processes over trials. Using a TUDA approach, we found that the timing of the cognitive processes involved in perceptual judgments can vary considerably over trials. This revealed that the sequence of processing states was consistent for all subjects and trials, even when the timing of these states varied. Furthermore, we found that the specific timing of states on each trial was related to the quality of performance over trials. Altogether, this work not only highlights the serious pitfalls and misleading interpretations that result from assuming stimulus processing to be synchronous across trials but can also open important avenues to investigate learning and quantify plasticity.
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http://dx.doi.org/10.1093/cercor/bhy290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6319313PMC
February 2019

Differential Effects of Salient Visual Events on Memory-Guided Attention in Adults and Children.

Child Dev 2019 07 8;90(4):1369-1388. Epub 2018 Oct 8.

University of Oxford.

Both salient visual events and scene-based memories can influence attention, but it is unclear how they interact in children and adults. In Experiment 1, children (N = 27; ages 7-12) were faster to discriminate targets when they appeared at the same versus different location as they had previously learned or as a salient visual event. In contrast, adults (N = 30; ages 18-31) responded faster only when cued by visual events. While Experiment 2 confirmed that adults (N = 27) can use memories to orient attention, Experiment 3 showed that, even in the absence of visual events, the effects of memories on attention were larger in children (N = 27) versus adults (N = 28). These findings suggest that memories may be a robust source of influence on children's attention.
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http://dx.doi.org/10.1111/cdev.13149DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6767380PMC
July 2019

Task-Evoked Dynamic Network Analysis Through Hidden Markov Modeling.

Front Neurosci 2018 28;12:603. Epub 2018 Aug 28.

Oxford Centre for Human Brain Activity, University of Oxford, Oxford, United Kingdom.

Complex thought and behavior arise through dynamic recruitment of large-scale brain networks. The signatures of this process may be observable in electrophysiological data; yet robust modeling of rapidly changing functional network structure on rapid cognitive timescales remains a considerable challenge. Here, we present one potential solution using Hidden Markov Models (HMMs), which are able to identify brain states characterized by engaging distinct functional networks that reoccur over time. We show how the HMM can be inferred on continuous, parcellated source-space Magnetoencephalography (MEG) task data in an unsupervised manner, without any knowledge of the task timings. We apply this to a freely available MEG dataset in which participants completed a face perception task, and reveal task-dependent HMM states that represent whole-brain dynamic networks transiently bursting at millisecond time scales as cognition unfolds. The analysis pipeline demonstrates a general way in which the HMM can be used to do a statistically valid whole-brain, group-level task analysis on MEG task data, which could be readily adapted to a wide range of task-based studies.
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http://dx.doi.org/10.3389/fnins.2018.00603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6121015PMC
August 2018

Not All Predictions Are Equal: "What" and "When" Predictions Modulate Activity in Auditory Cortex through Different Mechanisms.

J Neurosci 2018 10 24;38(40):8680-8693. Epub 2018 Aug 24.

Department of Neurology, New York University Langone Medical Center, New York, New York 10017,

Using predictions based on environmental regularities is fundamental for adaptive behavior. While it is widely accepted that predictions across different stimulus attributes (e.g., time and content) facilitate sensory processing, it is unknown whether predictions across these attributes rely on the same neural mechanism. Here, to elucidate the neural mechanisms of predictions, we combine invasive electrophysiological recordings (human electrocorticography in 4 females and 2 males) with computational modeling while manipulating predictions about content ("what") and time ("when"). We found that "when" predictions increased evoked activity over motor and prefrontal regions both at early (∼180 ms) and late (430-450 ms) latencies. "What" predictability, however, increased evoked activity only over prefrontal areas late in time (420-460 ms). Beyond these dissociable influences, we found that "what" and "when" predictability interactively modulated the amplitude of early (165 ms) evoked responses in the superior temporal gyrus. We modeled the observed neural responses using biophysically realistic neural mass models, to better understand whether "what" and "when" predictions tap into similar or different neurophysiological mechanisms. Our modeling results suggest that "what" and "when" predictability rely on complementary neural processes: "what" predictions increased short-term plasticity in auditory areas, whereas "when" predictability increased synaptic gain in motor areas. Thus, content and temporal predictions engage complementary neural mechanisms in different regions, suggesting domain-specific prediction signaling along the cortical hierarchy. Encoding predictions through different mechanisms may endow the brain with the flexibility to efficiently signal different sources of predictions, weight them by their reliability, and allow for their encoding without mutual interference. Predictions of different stimulus features facilitate sensory processing. However, it is unclear whether predictions of different attributes rely on similar or different neural mechanisms. By combining invasive electrophysiological recordings of cortical activity with experimental manipulations of participants' predictions about content and time of acoustic events, we found that the two types of predictions had dissociable influences on cortical activity, both in terms of the regions involved and the timing of the observed effects. Further, our biophysical modeling analysis suggests that predictability of content and time rely on complementary neural processes: short-term plasticity in auditory areas and synaptic gain in motor areas, respectively. This suggests that predictions of different features are encoded with complementary neural mechanisms in different brain regions.
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http://dx.doi.org/10.1523/JNEUROSCI.0369-18.2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6170983PMC
October 2018