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"Hedge, Craig"
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The cognitive cerebellum: linking microstructure to cognitive functions in a healthy population
2025
•Cerebellar Fractional Anisotropy modulates cognition in healthy individuals.•Cerebellar microstructure is linked to cognitive performance in healthy population.•Crus I Fractional Anisotropy is linked to language-related executive functions.•Lobule IX and Vermis IX Fractional Anisotropy associate with long-term memory.•Lobule V Fractional Anisotropy correlates with abstract reasoning.
The cerebellum is recognized for its role in motor control. However, it also plays a crucial part in modulating circuits involved in cognition and affect. While studies conducted on people with cerebellar disorders highlight both structural and functional links with cognition, research on cerebellar structure in the healthy population remains sparse. To better clarify the cerebellum’s role and operational mode in cognition, this multi-scale study explores the relationship between cognitive functions and cerebellar macrostructure and microstructure in healthy individuals. Macrostructural analysis focused on grey matter (GM) and white matter (WM) volumes, while microstructural evaluation used fractional anisotropy (FA) values.
Using a large normative cohort, the study examined cerebellar GM and WM volumes in 151 participants and FA in 83 participants. Cerebellar GM and WM volumes and FA values were correlated voxel-wise against the following cognitive domains: long-term memory, abstract reasoning, language-related executive functions, processing speed, and impulsive decision-making.
Significant positive correlations were found between FA in specific cerebellar regions and long-term memory (p = 0.030), abstract reasoning (p = 0.048), and language-related executive functions (p = 0.043). Additionally, cerebellar FA values negatively correlated in several clusters with reaction time (p = 0.001; p = 0.026; p = 0.045), indicating faster processing speed with higher FA. No significant associations were found between cerebellar GM/WM volumes and cognitive performance after Family Wise Error correction, except for a positive correlation between WM and reaction time (p = 0.023).
These findings highlight the cerebellum's microstructure role in cognition. FA may reflect the efficiency of communication between cerebellar and cortical regions, thus allowing the cerebellum to improve cognitive performance by updating internal models and correcting discrepancies between predictions and outcomes.
Journal Article
A Novel Framework to Measure Executive Function in Down Syndrome With Applications for Early Clinical Diagnosis of Dementia
by
Smith, Elizabeth
,
Hedge, Craig
,
Jarrold, Christopher
in
Accuracy
,
Adults
,
Alzheimer's disease
2019
Executive function (EF) decline is a consistent early sign of Alzheimer's disease (AD) among adults with Down syndrome (DS), which means that baseline measures of EF for individuals with DS are vital to allow detection of meaningful decline. We developed a framework to extract measures of three core components of EF (memory updating, inhibitory, and temporal components) within one task. Increases in memory load, inhibitory load, and temporal demands led to significant increases in reaction times and significant decreases in accuracy among 18 adults with DS and 18 typically developing matched individuals; thus, the expected effects of all three manipulations were detected. Good test-retest reliability indicated that this framework has the potential to provide a simple, baseline EF measure for individuals with DS.
Journal Article
Visually-induced dizziness is associated with sensitivity and avoidance across all senses
2020
Background
Persistent postural perceptual dizziness (PPPD) is a common chronic condition presenting in neurology and neuro-otology clinics. Symptoms lie on a spectrum in the general population. The cause is unknown and thought to involve interactions between visual and vestibular systems, but symptoms also correlate with anxiety and migraine.
Objective
To test whether PDDD symptoms are associated with reported differences in other senses (touch, hearing, smell and taste); to investigate possible mediation via anxiety or migraine; to discover the proportion of variance accountable to these non-vestibular factors.
Methods
We measured self-report multisensory sensitivity, anxiety, visual difficulties, visual discomfort and migraine in patients with PPPD (
N
= 29) and a large general population cohort (
N
> 1100). We used structural equation modelling to examine relationships between the factors using a step-wise approach.
Results
We found increased self-reported over-sensitivity in sensory domains beyond vision and balance in both patients with PPPD and non-clinical participants with more PPPD symptoms. SEM analysis revealed that anxiety partly, but not wholly, mediated this relationship. Adding visual difficulties and visual discomfort to the model allowed it to explain 50% of PPPD symptom variance. Most of the path coefficients and mediation effects in our model were unchanged between participants with and without migraine.
Conclusions
Our findings support the idea that PPPD is a complex neurological condition that includes broad perceptual factors, and may suggest that some brains are predisposed to generalised cross-modal sensory-overload. This may give rise to vulnerability to severe PPPD should a vestibular insult occur.
Journal Article
Selection in spatial working memory is independent of perceptual selective attention, but they interact in a shared spatial priority map
2015
We examined the relationship between the attentional selection of perceptual information and of information in working memory (WM) through four experiments, using a spatial WM-updating task. Participants remembered the locations of two objects in a matrix and worked through a sequence of updating operations, each mentally shifting one dot to a new location according to an arrow cue. Repeatedly updating the same object in two successive steps is typically faster than switching to the other object; this object switch cost reflects the shifting of attention in WM. In Experiment
1
, the arrows were presented in random peripheral locations, drawing perceptual attention away from the selected object in WM. This manipulation did not eliminate the object switch cost, indicating that the mechanisms of perceptual selection do not underlie selection in WM. Experiments
2a
and
2b
corroborated the independence of selection observed in Experiment
1
, but showed a benefit to reaction times when the placement of the arrow cue was aligned with the locations of relevant objects in WM. Experiment
2c
showed that the same benefit also occurs when participants are not able to mark an updating location through eye fixations. Together, these data can be accounted for by a framework in which perceptual selection and selection in WM are separate mechanisms that interact through a shared spatial priority map.
Journal Article
Are we capturing individual differences? Evaluating the test–retest reliability of experimental tasks used to measure social cognitive abilities
by
Shaw, Daniel J.
,
Ploszajski, Matthew
,
Birch-Hurst, Kayley
in
Adolescent
,
Adult
,
Behavioral Science and Psychology
2025
Social cognitive skills are crucial for positive interpersonal relationships, health, and wellbeing and encompass both automatic and reflexive processes. To assess this myriad of skills, researchers have developed numerous experimental tasks that measure automatic imitation, emotion recognition, empathy, perspective taking, and intergroup bias and have used these to reveal important individual differences in social cognition. However, the very reason these tasks produce robust experimental effects – low between-participant variability – can make their use as correlational tools problematic. We performed an evaluation of test–retest reliability for common experimental tasks that measure social cognition. One-hundred and fifty participants completed the race-Implicit Association Test (r-IAT), Stimulus–Response Compatibility (SRC) task, Emotional Go/No-Go (eGNG) task, Dot Perspective-Taking (DPT) task, and State Affective Empathy (SAE) task, as well as the Interpersonal Reactivity Index (IRI) and indices of Explicit Bias (EB) across two sessions within 3 weeks. Estimates of test–retest reliability varied considerably between tasks and their indices: the eGNG task had good reliability (ICC = 0.63–0.69); the SAE task had moderate-to-good reliability (ICC = 0.56–0.77); the r-IAT had moderate reliability (ICC = 0.49); the DPT task had poor-to-good reliability (ICC = 0.24–0.60); and the SRC task had poor reliability (ICC = 0.09–0.29). The IRI had good-to-excellent reliability (ICC = 0.76–0.83) and EB had good reliability (ICC = 0.70–0.77). Experimental tasks of social cognition are used routinely to assess individual differences, but their suitability for this is rarely evaluated. Researchers investigating individual differences must assess the test–retest reliability of their measures.
Journal Article
WAND: A multi-modal dataset integrating advanced MRI, MEG, and TMS for multi-scale brain analysis
2025
This paper introduces the Welsh Advanced Neuroimaging Database (WAND), a multi-scale, multi-modal imaging dataset comprising
in vivo
brain data from 170 healthy volunteers (aged 18–63 years), including 3 Tesla (3 T) magnetic resonance imaging (MRI) with ultra-strong (300 mT/m) magnetic field gradients, structural and functional MRI and nuclear magnetic resonance spectroscopy at 3 T and 7 T, magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS), together with trait questionnaire and cognitive data. Data are organised using the Brain Imaging Data Structure (BIDS). In addition to raw data, we provide brain-extracted T1-weighted images, and quality reports for diffusion, T1- and T2-weighted structural data, and blood-oxygen level dependent functional tasks. Reasons for participant exclusion are also included. Data are available for download through our GIN repository, a data access management system designed to reduce storage requirements. Users can interact with and retrieve data as needed, without downloading the complete dataset. Given the depth of neuroimaging phenotyping, leveraging ultra-high-gradient, high-field MRI, MEG and TMS, this dataset will facilitate multi-scale and multi-modal investigations of the healthy human brain.
Journal Article
Non-decision time: the Higg's boson of decision
by
Hedge, Craig
,
Sumner, Petroc
,
Bompas, Aline
in
Animal Behavior and Cognition
,
Cognitive ability
,
Decision making
2023
Generative models of decision now permeate all subfields of psychology, cognitive and clinical neuroscience. To successfully represent decision mechanisms, it is necessary to also assume the presence of delays for sensory and motor information to travel through the brain; but like the Higg's boson in particle physics, directly observing this \"non-decision time\" from behaviour long appeared beyond reach. Here, we describe and apply a set of methods to empirically measure and characterise the properties of non-decision time in fast visually guided decisions (without requiring modelling assumptions). We gather 11 datasets from humans and monkeys from multiple labs and validate the method by showing that visual properties (brightness, colour, size) consistently affect empirically measured non-decision time, as predicted by neurophysiology. We then show that endogenous factors (pro-active slowing, attention) consistently do not affect non-decision time, in contrast to widespread reports based on model fits. Last, contrasting empirically observed non-decision time with estimates from the EZ, DDM and LBA models, we conclude that models cannot be generally trusted to provide valid estimates, either at a group level or for individual differences, and propose a hybrid approach that combines our empirical method with standard modelling.Competing Interest StatementThe authors have declared no competing interest.Footnotes* https://osf.io/gz9uc/?view_only=30c56b2c454949ddbe2b4d56da5f87f6
Temporal structure in sensorimotor variability: a stable trait, but what for?
by
Hedge, Craig
,
Van Vugt, Marieke K
,
Marlou Nadine Perquin
in
Attention deficit hyperactivity disorder
,
Cognitive ability
,
Human performance
2022
Human performance shows substantial endogenous variability over time, and this variability is a robust marker of individual differences. Of growing interest to psychologists is the realisation that variability is not fully random, but often exhibits temporal dependencies. However, their measurement and interpretation come with several controversies. Furthermore, their potential benefit for studying individual differences in healthy and clinical populations remains unclear. Here we gather new and archival datasets featuring 11 sensorimotor and cognitive tasks across 526 participants, to examine individual differences in temporal structures. We first investigate intra-individual repeatability of the most common measures of temporal structures - to test their potential for capturing stable individual differences. Secondly, we examine inter-individual differences in these measures using: 1) task performance assessed from the same data, 2) meta-cognitive ratings of on-taskness from thought probes occasionally presented throughout the task, and 3) self-assessed attention-deficit related traits. Across all datasets, autocorrelation at lag 1 and Power Spectra Density slope showed high intra-individual repeatability across sessions and correlated with task performance. The Detrended Fluctuation Analysis slope showed the same pattern, but less reliably. The long-term component (d) of the ARFIMA(1,d,1) model showed poor repeatability and no correlation to performance. Overall, these measures failed to show external validity when correlated with either mean subjective attentional state or self-assessed traits between participants. Thus, some measures of serial dependencies may be stable individual traits, but their usefulness in capturing individual differences in other constructs typically associated with variability in performance seems limited. We conclude with comprehensive recommendations for researchers.Competing Interest StatementThe authors have declared no competing interest.Footnotes* Added two tables (Table 1 and 2); added credible intervals to all results; parts of Methods moved to Appendix; short additions to General Discussion
Inability to improve performance with control shows limited access to inner states
2019
Any repeatedly performed action is characterised by endogenous variability, affecting both speed and accuracy - for a large part presumably caused by fluctuations in underlying brain and body states. The current research questions were: 1) whether such states are accessible to us, and 2) whether we can act upon this information to reduce variability. For example, when playing a game of darts, there is an implicit assumption that people can wait to throw until they are in the \"right\" perceptual-attentional state. If this is true, taking away the ability to self-pace the game should worsen performance. We first tested precisely this assumption asking participants to play darts in a self-paced and a fixed-paced condition. There was no benefit of self-pacing, showing that participants were unable to use such control to improve their performance and reduce their variability. Next, we replicated these findings in two computer-based tasks, in which participants performed a rapid action-selection and a visual detection task in one self-paced and three forced-paced conditions. Over four different empirical tests, we show that the self-paced condition did not lead to improved performance or reduced variability, nor to reduced temporal dependencies in the reaction time series. Overall, it seems that, if people have any access to their fluctuating performance-relevant inner states, this access is limited and not relevant for upcoming performance.