Biology subjects

Rich, A. N.

Publications and source records attributed to Rich, A. N..

15 recordsLinked to original sources

bioRxiv2026

Associative Visual Memory in Aphantasia: Evidence for Intact Object and Spatial Memory, Metacognitive Awareness, but Different Strategies

Many forms of memory are thought to rely on visual imagery, but individuals who report lacking visual imagery (aphantasia) can still perform various memory tasks. There is, however, evidence that aphantasia may lead to less detailed autobiographical memories, suggesting there may be deficits in the underlying cognitive processes that support personal memories. One such process is associative memory, which requires binding of different types of information. Here, we tested whether associative visual memory is intact in aphantasia. We assessed 72 self-identified individuals with aphantasia and 77 controls who reported having visual imagery. Participants completed an associative memory task which involved memorising displays where a unique object in a specific location was associated with a particular colour fixation point. Individuals with aphantasia performed equivalently to controls for object locations and outperformed controls on the associated object-identity. In addition, whereas controls were significantly worse at remembering associated object-identity than object-location, individuals with aphantasia showed no such difference. Both groups showed good metacognitive performance evidenced by a positive correlation between confidence and accuracy; there were no significant differences in confidence between the groups. Reported strategies varied between groups: a large proportion of control participants reported using visual imagery and self-reported use of imagery positively correlated with performance. Conversely, individuals with aphantasia mostly reported using nonvisual strategies to remember the associations. Overall, the findings suggest that individuals with aphantasia can form associative memories using nonvisual strategies. Thus, difficulties with autobiographical memory in aphantasia seem unlikely to be due to fundamental issues with associative memory.

neuroscience↗

bioRxiv2025

Using EEG to Detect Lapses in Sustained Attention to Moving Stimuli

Sustaining attention is effortful but crucial for daily life. Despite this, attentional lapses are common and can have fatal consequences (e.g., when driving). The spontaneous nature of these lapses make studying their underlying phenomena elusive. As such, methods capable of determining when lapses have occurred may be fruitful research tools, with the potential to save lives if implemented within real world settings. Here, we capitalised on a recent hierarchical classification method, which uses multivariate decoding to index how well human observers sustain their attention within a dynamic visual environment. We asked whether this method could be used to anticipate behavioural errors based on neural activity measured with electroencephalography (EEG). We first decoded patterns of EEG activity that systematically correlated with critical aspects of a Multiple Object Monitoring (MOM) task. The extent to which we could decode this information depended on whether a stimulus was relevant for behaviour, which was lower before participants failed to detect (or missed) target stimuli, presumably due to attentional lapses. Here, we exploited this drop in neural decodability to predict whether errors were about to occur on each trial. The results form a foundation for sensitive and specific methods to objectively detect lapses in sustained attention based on patterns of brain activity.

neuroscience↗

bioRxiv2024

Spatiotemporal characterisation of information coding and exchange in the multiple demand network

The multiple-demand network (MDN), a brain-wide system with nodes near sensory and higher-order cognitive regions, has been suggested to integrate and exchange task-related information across the brain, supporting cognitive task performance. However, the profile of information coding and the role of each node within this network in information exchange remain unclear. To address this, we combined fMRI and MEG data in a challenging stimulus-response mapping task. Using multivariate pattern analysis (MVPA), we decoded various forms of task information, including coarse and fine stimulus details, motor responses, and stimulus-response mapping rules, across the MDN and visual regions. Early in the task, visual regions responded to large physical differences in stimuli, while later on, fine stimulus information and rules were encoded across the MDN. To assess information exchange between regions, we developed Fusion-RCA, a novel connectivity analysis method based on fMRI-MEG fusion profiles. Our findings revealed significant transfer of fine stimulus information, rules, and responses, but little evidence for the transfer of coarse stimulus information. These results highlight distinct information encoding patterns within MDN nodes and suggest that the anterior cingulate cortex (ACC) plays a key role in distributing task-relevant information. This study offers new insights into the dynamic function of the MDN and introduces Fusion-RCA as a powerful tool for exploring brain-wide information transfer.

neuroscience↗

bioRxiv2023

The validated touch-video database

Visually observing a touch quickly reveals who is being touched, how it might feel, and the broader social or emotional context, shaping our interpretation of such interactions. Investigating these dimensions is essential for understanding how tactile experiences are processed individually and how we empathise with observed sensations in others. Here, we expand available resources for studying visually perceived touch by providing a wide-ranging set of dynamic interactions that specifically focus on the sensory qualities of touch. The Validated Touch-Video Database (VTD) consists of a set of 90 videos depicting tactile interactions with a stationary left hand, viewed from a first-person perspective. In each video, a second hand makes contact either directly (e.g., with fingers or an open palm) or using an object (e.g., a soft brush or scissors), with variations across dimensions such as hedonic qualities, arousal, threat, touch type, and the object used. Validation by 350 participants (283 women, 66 men, 1 non-binary) involved categorising the videos as neutral, pleasant, unpleasant, or painful and rating arousal and threat levels. Our findings reveal high inter-subject agreement, with painful touch videos eliciting the highest arousal and threat ratings, while neutral touch videos served as a baseline. Exploratory analyses revealed women rated the videos as more threatening and painful than men, suggesting potential gender differences in the visual perception of negatively valenced touch stimuli. The VTD provides a comprehensive resource for researchers investigating the sensory and emotional dimensions of observed touch.

neuroscience↗

bioRxiv2022

Precise overlapping neural representations between feeling and seeing touch in people with high tactile empathy

Simulation theories propose that vicarious touch arises when seeing someone else being touched triggers corresponding representations of being touched. Prior electroencephalography (EEG) findings show that seeing touch modulates both early and late somatosensory responses (measured with or without direct tactile stimulation). Functional Magnetic Resonance Imaging (fMRI) studies have shown that seeing touch increases somatosensory cortical activation. These findings have been taken to suggest that when we see someone being touched, we simulate that touch in our sensory systems. The somatosensory overlap when seeing and feeling touch differs between individuals, potentially underpinning variation in vicarious touch experiences. Increases in amplitude (EEG) or cerebral blood flow response (fMRI), however, are limited in that they cannot test for the information contained in the neural signal: seeing touch may not activate the same information as feeling touch. Here, we use time-resolved multivariate pattern analysis on whole-brain EEG data from people with and without vicarious touch experiences to test whether seen touch evokes overlapping neural representations with the first-hand experience of touch. Participants felt touch to the fingers (tactile trials) or watched carefully matched videos of touch to another persons fingers (visual trials). In both groups, EEG was sufficiently sensitive to allow decoding of touch location (little finger vs. thumb) on tactile trials. However, only in individuals who reported feeling touch when watching videos of touch could a classifier trained on tactile trials distinguish touch location on visual trials. This demonstrates that, for people who experience vicarious touch, there is overlap in the information about touch location held in the neural patterns when seeing and feeling touch. The timecourse of this overlap implies that seeing touch evokes similar representations to later stages of tactile processing. Therefore, while simulation may underlie vicarious tactile sensations, our findings suggest this involves an abstracted representation of directly felt touch.

neuroscience↗

bioRxiv2021

Linking the brain with behaviour: the neural dynamics of success and failure in goal-directed behaviour

The human brain is extremely flexible and capable of rapidly selecting relevant information in accordance with task goals. Regions of frontoparietal cortex flexibly represent relevant task information such as task rules and stimulus features when participants perform tasks successfully, but less is known about how information processing breaks down when participants make mistakes. This is important for understanding whether and when information coding recorded with neuroimaging is directly meaningful for behaviour. Here, we used magnetoencephalography (MEG) to assess the temporal dynamics of information processing, and linked neural responses with goal-directed behaviour by analysing how they changed on behavioural error. Participants performed a difficult stimulus-response task using two stimulus-response mapping rules. We used time-resolved multivariate pattern analysis to characterise the progression of information coding from perceptual information about the stimulus, cue and rule coding, and finally, motor response. Response-aligned analyses revealed a ramping up of perceptual information prior to a correct response, suggestive of internal evidence accumulation. Strikingly, when participants made a stimulus-related error, and not when they made other types of errors, patterns of activity initially reflected the stimulus presented, but later reversed, and accumulated towards a representation of the incorrect stimulus. This suggests that the patterns recorded at later timepoints reflect an internally generated stimulus representation that was used to make the (incorrect) decision. These results illustrate the orderly and overlapping temporal dynamics of information coding in perceptual decision-making and show a clear link between neural patterns in the late stages of processing and behaviour.

neuroscience↗

bioRxiv2021

Undivided attention: The temporal effects of attention dissociated from decision, memory, and expectation

Selective attention prioritises relevant information amongst competing sensory input. Time-resolved electrophysiological studies have shown stronger representation of attended compared to unattended stimuli, which has been interpreted as an effect of attention on information coding. However, because attention is often manipulated by making only the attended stimulus a target to be remembered and/or responded to, many reported attention effects have been confounded with target-related processes such as visual short-term memory or decision-making. In addition, the effects of attention could be influenced by temporal expectation. The aim of this study was to investigate the dynamic effect of attention on visual processing using multivariate pattern analysis of electroencephalography (EEG) data, while 1) controlling for target-related confounds, and 2) directly investigating the influence of temporal expectation. Participants viewed rapid sequences of overlaid oriented grating pairs at fixation while detecting a "target" grating of a particular orientation. We manipulated attention, one grating was attended and the other ignored, and temporal expectation, with stimulus onset timing either predictable or not. We controlled for target-related processing confounds by only analysing non-target trials. Both attended and ignored gratings were initially coded equally in the pattern of responses across EEG sensors. An effect of attention, with preferential coding of the attended stimulus, emerged approximately 230ms after stimulus onset. This attention effect occurred even when controlling for target-related processing confounds, and regardless of stimulus onset predictability. These results provide insight into the effect of attention on the dynamic processing of competing visual information, presented at the same time and location.

neuroscience↗

bioRxiv2021

Selective attention and decision-making have separable neural bases in space and time

Attention and decision-making processes are fundamental to cognition. However, they are usually experimentally confounded, making it difficult to link neural observations to specific processes. Here we separated the effects of selective attention from the effects of decision-making on human brain activity, using a two-stage task where the attended stimulus and decision were orthogonal and separated in time. Multivariate pattern analyses of multimodal neuroimaging data revealed the dynamics of perceptual and decision-related information coding through time (magnetoencephalography (MEG)), space (functional Magnetic Resonance Imaging (fMRI)), and their combination (MEG-fMRI fusion). Our MEG results showed an effect of attention before decision-making could begin, and fMRI results showed an attention effect in early visual and frontoparietal regions. Model-based MEG-fMRI fusion suggested that attention boosted stimulus information in frontoparietal and early visual regions before decision-making was possible. Together, our results suggest that attention affects neural stimulus representations in frontoparietal regions independent of decision-making.

neuroscience↗

bioRxiv2020

Vigilance decrements in the brain: neural signatures can predict behavioural errors before they happen

There are now many environments in which humans need to monitor moving displays and only rarely act, such as train control and driving autonomous vehicles; lapses of attention in these circumstances can have tragic consequences. Problematically, we know that it is difficult to sustain attention under these monitoring or vigilance conditions and performance drops: when target events are rare, we tend to miss them, or are slower to respond. This rare target effect becomes more marked with longer tasks, known as a vigilance decrement. Despite the importance, we still have limited understanding of how the brain processes information during monitoring, particularly with dynamic stimuli, and how this processing changes when attention lapses. Here, we designed a multiple-object monitoring (MOM) paradigm that required sustained attention to dynamic stimuli, and used multivariate analyses of magnetoencephalography (MEG) data to examine how the neural representation of the information in the display varied with target frequency and time on the task. Behavioural performance decreased over time for the rare target (monitoring) condition, but not for the frequent target (active) condition. This change was mirrored in the neural results: under monitoring conditions, there was weaker coding of the critical distance between objects during time periods when vigilance decrements in performance occurred. There was also weaker informational connectivity between peri-occipital and peri-frontal brain areas in rare versus frequent target conditions. We developed a new analysis which used the strength of information decoding to predict whether the participant was going to miss the target on a given trial. We could predict behavioural errors more than a second before they occurred. This provides a first step in developing methods to predict and pre-empt behavioural errors due to lapses in attention and provides new insight into how vigilance decrements are reflected in information coding in the brain.

neuroscience↗

bioRxiv2020

Concurrent neuroimaging and neurostimulation reveals a causal role for dlPFC in coding of task-relevant information

The way in which the brain prioritises processing of information relevant for our current goals is widely contested. Many studies implicate the dorsolateral prefrontal cortex (dlPFC), and propose that it drives brain-wide focus by biasing processing in favour of relevant information. An alternative, however, is that dlPFC is involved in the inhibition of irrelevant information. Here, we address this longstanding debate using the inferentially powerful approach of applying transcranial magnetic stimulation during functional magnetic resonance imaging (concurrent TMS-fMRI) and testing for changes in information coding using multivariate pattern analysis (MVPA). We ask whether dlPFC plays a causal role in prioritising information processing, and whether this is through selection of relevant information or inhibition of irrelevant information. Participants attended to one object feature whilst ignoring another feature of the same object. We reasoned that, if dlPFC is necessary for selection, active (disruptive) TMS should decrease coding of attended information compared to the low intensity (control) condition. Conversely, if right dlPFC is crucial for inhibition, active TMS should increase coding of irrelevant information relative to the control condition. The results showed that active TMS decreased coding of relevant information throughout the frontoparietal multiple demand regions, and that this impact was significantly stronger than the effect of TMS on irrelevant information coding, which was not statistically detectable. These data provide causal evidence for a specific role of dlPFC in supporting the representation of task-relevant information and demonstrate the crucial insights into high level cognitive-neural mechanisms possible with the combination of TMS-fMRI and MVPA.

neuroscience↗

bioRxiv2019

Foveal feedback supports peripheral perception of both object color and form

Evidence from neuroimaging and brain stimulation studies suggest that visual information about objects in the periphery is fed back to foveal retinotopic cortex in a separate representation that is essential for peripheral perception. The characteristics of this phenomenon has important theoretical implications for the role fovea-specific feedback might play in perception. In this work, we employed a recently developed behavioral paradigm to explore whether late disruption to central visual space impaired perception of color. First, participants performed a shape discrimination task on colored novel objects in the periphery while fixating centrally. Consistent with the results from previous work, a visual distractor presented at fixation ~100ms after presentation of the peripheral stimuli impaired sensitivity to differences in peripheral shapes more than a visual distractor presented at other stimulus onset asynchronies. In a second experiment, participants performed a color discrimination task on the same colored objects. In a third experiment, we further tested for the foveal distractor effect with stimuli restricted to a low-level feature by using homogenous color patches. These two latter experiments resulted in a similar pattern of behavior: a central distractor presented at the critical stimulus onset asynchrony impaired sensitivity to peripheral color differences, but, importantly, the magnitude of the effect depended on whether peripheral objects contained complex shape information. These results taken together suggest that feedback to the foveal confluence is a component of visual processing supporting perception of both object form and color.

neuroscience↗

bioRxiv2019

Meaningful patterns of information in the brain revealed through analysis of errors

Great excitement has surrounded our ability to decode task information from human brain activity patterns, reinforcing the dominant view of the brain as an information processor. We tested a fundamental but overlooked assumption: that such decodable information is actually used by the brain to generate cognition and behaviour. Participants performed a challenging stimulus-response task during fMRI. Our novel analyses trained a pattern classifier on data from correct trials, and used it to examine stimulus and rule coding on error trials. There was a striking interaction in which frontoparietal cortex systematically represented incorrect rule but correct stimulus information when participants used the wrong rule, and incorrect stimulus but correct rule information on other types of errors. Visual cortex, by contrast, did not code correct or incorrect information on error. Thus behaviour was tightly linked to coding in frontoparietal cortex and only weakly linked to coding in visual cortex. Human behaviour may indeed result from information-like patterns of activity in the brain, but this relationship is stronger in some brain regions than in others. Testing for information coding on error can help establish which patterns constitute behaviourally-meaningful information.

neuroscience↗

bioRxiv2019

Visual body form and orientation cues do not modulate visuo-tactile temporal integration

Body ownership relies on spatiotemporal correlations between multisensory signals and visual cues specifying oneself such as body form and orientation. The mechanism for the integration of bodily signals remains unclear. One approach to model multisensory integration that has been influential in the multisensory literature is Bayesian causal inference. This specifies that the brain integrates spatial and temporal signals coming from different modalities when it infers a common cause for inputs. As an example, the rubber hand illusion shows that visual form and orientation cues can promote the inference of a common cause (ones body) leading to spatial integration shown by a proprioceptive drift of the perceived location of the real hand towards the rubber hand. Recent studies investigating the effect of visual cues on temporal integration, however, have led to conflicting findings. These could be due to task differences, variation in ecological validity of stimuli and/or small samples. In this pre-registered study, we investigated the influence of visual information on temporal integration using a visuo-tactile temporal order judgement task with realistic stimuli and a sufficiently large sample determined by Bayesian analysis. Participants viewed videos of a touch being applied to plausible or implausible visual stimuli for ones hand (hand oriented plausibly, hand rotated 180 degrees, or a sponge) while also being touched at varying stimulus onset asynchronies. Participants judged which stimulus came first: viewed or felt touch. Results show that visual cues do not modulate visuo-tactile temporal order judgements. This is not in line with the idea that bodily signals indicating oneself influence the integration of multisensory signals in the temporal domain. The current study emphasises the importance of rigour in our methodologies and analyses to advance the understanding of how properties of multisensory events affect the encoding of temporal information in the brain.

neuroscience↗

bioRxiv2019

Towards an individualised neural assessment of receptive language in children

PurposeWe aimed to develop a non-invasive neural test of language comprehension to use with non-speaking children for whom standard behavioural testing is unreliable (e.g., minimally-verbal autism). Our aims were three-fold. First, we sought to establish the sensitivity of two auditory paradigms to elicit neural responses in individual neurotypical children. Second, we aimed to validate the use of a portable and accessible electroencephalography (EEG) system, by comparing its recordings to those of a research-grade system. Third, in light of substantial inter-individual variability in individuals neural responses, we assessed whether multivariate decoding methods could improve sensitivity. MethodsWe tested the sensitivity of two child-friendly covert N400 paradigms. Thirty-one typically developing children listened to identical spoken words that were either strongly predicted by the preceding context or violated lexical-semantic expectations. Context was given by a cue word (Experiment 1) or sentence frame (Experiment 2) and participants either made an overall judgement on word relatedness or counted lexical-semantic violations. We measured EEG concurrently from a research-grade system, Neuroscans SynAmps2, and an adapted gaming system, Emotivs EPOC+. ResultsWe found substantial inter-individual variability in the timing and topology of N400-like effects. For both paradigms and EEG systems, traditional N400 effects at the expected sensors and time points were statistically significant in around 50% of individuals. Using multivariate analyses, detection rate increased to 88% of individuals for the research-grade system in the sentences paradigm, illustrating the robustness of this method in the face of inter-individual variations in topography. ConclusionsThere was large inter-individual variability in neural responses, suggesting inter-individual variation in either the cognitive response to lexical-semantic violations, and/or the neural substrate of that response. Around half of our neurotypical participants showed the expected N400 effect at the expected location and time point. A low-cost, accessible EEG system provided comparable data for univariate analysis but was not well suited to multivariate decoding. However, multivariate analyses with a research-grade EEG system increased our detection rate to 88% of individuals. This approach provides a strong foundation to establish a neural index of language comprehension in children with limited communication.

animal behavior and cognition↗

bioRxiv2018

Limits on visual awareness for multiple objects: a bottleneck in low-level edge detection rather than high-level representational architecture

Our capacity to become aware of visual stimuli is limited. Investigating these limits, Cohen et al. (2015, Journal of Cognitive Neuroscience) found that certain object categories (e.g., faces) were more effective in blocking awareness of other categories (e.g., buildings) than other combinations (e.g., cars/chairs) in the continuous flash suppression (CFS) task. They also found that more category-pair representational similarity in higher visual cortex was related to longer category-pair breakthrough times suggesting a high-level representational architecture bottleneck for visual awareness. As the cortical representations of hands and tools overlap, these categories are ideal to test this further. We conducted CFS experiments and predicted longer breakthrough times for hands/tools compared to other pairs. In contrast to these predictions, participants were generally faster at detecting targets masked by hands or tools compared to other mask categories when giving manual (Experiment 1) or vocal responses (Experiment 2). Furthermore, we found the same inefficient mask effect for hands in the context of the categories used by Cohen et al. (2015) and found a similar behavioural pattern as the original paper (Experiment 3). Exploring potential low-level explanations, we found that the category average for edges (e.g. hands have less detail compared to cars) was the best predictor for the data. However, these category-specific image characteristics could not completely account for the Cohen et al. (2015) category pattern or for the hand/tool effects. Thus, several low- and high-level object category-specific limits for visual awareness are plausible and more investigations are needed to further tease these apart.

neuroscience↗