Biology subjects

Ghafari, T.

Publications and source records attributed to Ghafari, T..

6 recordsLinked to original sources

bioRxiv2026

Laterality of subcortical structures predicts spontaneous brain dynamics

Subcortical structures play a key role in shaping cortical computation through distributed cortico-subcortical networks, yet it remains unclear whether individual differences in subcortical anatomy are reflected in resting-state cortical oscillations. We analysed resting-state magnetoencephalography (MEG) and structural MRI from 533 healthy adults in the Cambridge Centre for Ageing and Neuroscience (CamCAN) cohort to test whether hemispheric asymmetries in subcortical volume predict asymmetries in cortical oscillatory power. Lateralisation indices were calculated for subcortical volumes and for oscillatory power across homologous MEG sensor pairs. Cluster-based permutation testing revealed frequency-specific associations between subcortical anatomy and cortical activity. Globus pallidus asymmetry was positively associated with posterior alpha-band power lateralisation, putamen and caudate asymmetries were associated with beta-band lateralisation, and hippocampal asymmetry was negatively associated with delta-band lateralisation. These findings extend previous task-based observations linking pallidal anatomy with alpha oscillations to the resting state and demonstrate that distinct subcortical structures are associated with specific cortical frequency bands. Our results suggest that resting-state MEG captures functional signatures of cortico-subcortical organisation and provides a non-invasive framework for studying healthy ageing and disorders involving subcortical degeneration.

neuroscience↗

bioRxiv2026

OPM-FLUX: A Pipeline for OPM MEG Data Analysis

Optically pumped magnetometer-based magnetoencephalography (OPM-MEG) has recently emerged as a powerful neuroimaging approach in cognitive neuroscience, extending beyond the limitations of conventional cryogenic systems with greater experimental flexibility and wearable recording. Despite these advantages, standardised data analysis frameworks specifically tailored to OPM technology are still lacking, leading to variability in processing choices and reduced reproducibility across laboratories and hardware platforms. We introduce OPM-FLUX, a comprehensive and fully documented end-to-end analysis pipeline developed for OPM-MEG data. The pipeline defines a clear sequence of preprocessing, noise suppression, artifact handling, spectral analysis, evoked response analysis along with recommended parameter settings. It also includes source reconstruction to identify where in the brain the signals originate. In addition, OPM-FLUX supports multivariate pattern analysis (MVPA), enabling time-resolved decoding of cognitive processes from sensor level data. OPM-FLUX is implemented in MNE-Python and distributed as interactive Jupyter Notebooks that combine executable code with detailed methodological explanations and graphical outputs. The pipeline further provides standardized reporting templates and a data acquisition Standard Operating Procedure to facilitate preregistration, consistent documentation, and standard practices across research sites. The workflow is demonstrated using openly available datasets acquired from both Cerca/QuSpin and FieldLine OPM systems during a visuospatial attention paradigm that modulates alpha, beta, and gamma oscillations and elicits event-related responses. By supporting multiple OPM platforms and promoting consistent methodological choices, OPM-FLUX enhances transparency, comparability, and replication in OPM-MEG research. The pipeline also serves as an educational resource for students and researchers entering the field and is designed to evolve alongside ongoing technological and methodological advances in OPM-based brain imaging.

neuroscience↗

bioRxiv2025

Hemispheric laterality of the putamen predicts pseudoneglect

Healthy individuals tend to exhibit a subtle leftward attentional bias, a phenomenon termed pseudoneglect. While this bias is thought to reflect a right-hemisphere dominance when allocating spatial attention, the contribution of subcortical structures remains poorly understood. Although lesion and neuroimaging studies in clinical populations have implicated asymmetries in the basal ganglia and thalamus to dysfunction in spatial attention, it remains unclear whether naturally occurring subcortical asymmetries in healthy individuals predict behavioural biases in spatial attention. In this study, we investigated whether volumetric asymmetries in subcortical structures are associated with biases in spatial attention in a non-clinical population. This was achieved by using the landmark task to assess spatial biases, alongside acquiring T1-weighted MRI data from 44 healthy participants. The subcortical regions were segmented using the FIRST algorithm to estimate the volumetric asymmetry of specific regions. We found that variability in pseudoneglect was predicted by the degree of leftward lateralisation of putamen volume, indicating that the putamen contributes to the magnitude of spatial attention biases. This also suggests that the left putamen may support right-hemisphere neocortical dominance through the indirect pathway. These findings bridge anatomical and behavioural measures, highlighting the functional relevance of subcortical asymmetry in shaping attentional processes in the healthy brain. Our findings pave the way for early diagnosis of neurological disorders associated with subcortical atrophies including Parkinsons Disease and dementia. Significance StatementHemispheric dominance in cortical networks shape attentional biases, but the role of subcortical structures remains poorly understood. Here we show that natural variability in the lateralisation of the putamen predicts individual differences in pseudoneglect--a subtle leftward bias in spatial attention observed in healthy adults. Using MRI and psychophysics, we demonstrate that greater leftward putamen asymmetry is associated with stronger leftward bias, independent of eye dominance and microsaccadic behaviour, and moderated by handedness. These findings reveal a structural subcortical basis for attentional asymmetries and suggest that simple behavioural measures could serve as non-invasive markers of early subcortical changes relevant to disorders such as Parkinsons disease, Alzheimers disease, and ADHD.

neuroscience↗

bioRxiv2024

STEMorph: Morphed Emotional Face Stimuli

Emotion recognition through facial expressions is crucial for interpreting social cues. However, it is often influenced by biases, i.e., systematic recognition advantages for particular emotions. Nevertheless, these biases are inconsistently reported across studies, likely due to methodological variations which underline the necessity for a standardized approach. Traditional face morphing methods can create unnatural-looking stimuli, and may confound the interpretation of emotions. To address this issue, we here introduce STEMorph, a validated stimulus set based on the NimStim set. We employed neutral-anchored morphing and neural-network-generated masks to reduce morphing artifacts and preserve the coherence of the depicted expressions. We validated our stimulus set by having participants rate each face on a 9-point scale ranging from angry to happy, assessing the perceived emotional intensity. STEMorphs validity was confirmed through linear mixed-effects modelling, showing a strong association between subjective ratings and intended morph level while accounting for other effects. Moreover, aligning with previous research highlighting gender as a key factor in emotion recognition, STEMorph also showed variation across participant-gender dimension. STEMorphs reliability was confirmed through a two-week follow-up rating session with a subgroup of the same participants. By introducing a controlled and empirically evaluated stimulus set of morphed emotional faces, STEMorph provides a useful resource for future investigations of facial emotion recognition.

neuroscience↗

bioRxiv2023

Modulation of alpha oscillations by attention is predicted by hemispheric asymmetries of subcortical regions.

Evidence suggests that subcortical structures play a role in high-level cognitive functions such as the allocation of spatial attention. While there is abundant evidence in humans for posterior alpha band oscillations being modulated by spatial attention, little is known about how subcortical regions contribute to these oscillatory modulations, particularly under varying conditions of cognitive challenge. In this study, we combined MEG and structural MRI data to investigate the role of subcortical structures in controlling the allocation of attentional resources by employing a cued spatial attention paradigm with varying levels of perceptual load. We asked whether hemispheric lateralization of volumetric measures of the thalamus and basal ganglia predicted the hemispheric modulation of alpha-band power. Lateral asymmetry of the globus pallidus, caudate nucleus, and thalamus predicted attention-related modulations of posterior alpha oscillations. When the perceptual load was applied to the target and the distractor was salient caudate nucleus asymmetry predicted alpha-band modulations. Globus Pallidus was predictive of alpha-band modulations when either the target had a high load, or the distractor was salient, but not both. Finally, the asymmetry of the thalamus predicted alpha band modulation when neither component of the task was perceptually demanding. In addition to delivering new insight into the subcortical circuity controlling alpha oscillations with spatial attention, our finding might also have clinical applications. We provide a framework that could be followed for detecting how structural changes in subcortical regions that are associated with neurological disorders can be reflected in the modulation of oscillatory brain activity.

neuroscience↗

bioRxiv2023

An adversarial collaboration to critically evaluate theories of consciousness

Different theories explain how subjective experience arises from brain activity1,2. These theories have independently accrued evidence, yet, confirmation bias and dependence on design choices hamper progress in the field3. Here, we present an open science adversarial collaboration which directly juxtaposes Integrated Information Theory (IIT)4,5 and Global Neuronal Workspace Theory (GNWT)6-10, employing a theory-neutral consortium approach11,12. We investigate neural correlates of the content and duration of visual experience. The theory proponents and the consortium developed and preregistered the experimental design, divergent predictions, expected outcomes, and their interpretation12. 256 human subjects viewed suprathreshold stimuli for variable durations while neural activity was measured with functional magnetic resonance imaging, magnetoencephalography, and electrocorticography. We find information about conscious content in visual, ventro-temporal and inferior frontal cortex, with sustained responses in occipital and lateral temporal cortex reflecting stimulus duration, and content-specific synchronization between frontal and early visual areas. These results confirm some predictions of IIT and GNWT, while substantially challenging both theories: for IIT, a lack of sustained synchronization within posterior cortex contradicts the claim that network connectivity specifies consciousness. GNWT is challenged by the general lack of ignition at stimulus offset and limited representation of certain conscious dimensions in prefrontal cortex. Beyond challenging the theories themselves, we present an alternative approach to advance cognitive neuroscience through a principled, theory-driven, collaborative effort. We highlight the challenges to change peoples mind 13 and the need for a quantitative framework integrating evidence for systematic theory testing and building.

neuroscience↗