Authors:

HUMPHREYS, G., LAMBON RALPH, M.

Reference:

Year of publication:

In Press

CBU number:

9182

Abstract:

Improving our understanding of the neural network engaged by different forms of speech production is a crucial step for both cognitive and clinical neuroscience. We achieved this aim by exploring two of the most commonly utilised speech production paradigms in research and the clinic, which have been rarely, if ever, compared directly: picture naming and category fluency. This goal was achieved in this two study investigation through a full ALE meta-analysis as well as a targeted fMRI study. Harnessing the similarities and differences between the two tasks offers a powerful methodology to delineate the core systems recruited for speech production, as well as revealing task-specific processes. The results showed that both tasks engaged a bilateral fronto-temporal speech production network, including executive and motor frontal areas, as well as semantic representational regions in the ATL, bilaterally. In addition, it was found that the extent of relative frontal lateralisation was task-dependent with the more executively-demanding category fluency task showing augmented left hemisphere activation. The results have implications for neurocomputational speech production models and the clinical assessment of speech production impairments. Data is available - https://osf.io/pe7un/

URL:

Data for this project is available at: https://osf.io/pe7un/

Authors:

ARZOUNIAN, D., GUERIT, F., DEEKS, J.M., GARCIA, C., DE GROOTE, E., Bance, M., CARLYON, R.P.

Reference:

Year of publication:

2025

CBU number:

9178

Abstract:

Studies investigating objective measures of auditory perception when using cochlear implants (CIs) differ in the stimuli used and in the neural response measured. The present study aims to disentangle the effects of response type and of stimulus type on neural response properties. We report three measures corresponding with separate neural latencies, all collected from the same 19 CI recipients and with the same stimulus, consisting of a continuous low-rate electrical pulse train of about 40 pulses per second (pps). These measures comprise the electrically evoked compound action potential (eCAP), auditory brainstem response (eABR), and auditory steady-state response (eASSR), having putative neural generators in peripheral (auditory nerve), subcortical (brainstem), and thalamo-cortical auditory regions, respectively. When assessing correlations across CI recipients, we found that the growth of eASSR amplitude with stimulus level was correlated with that of eCAP amplitude and predictive of the just-noticeable-to-comfortable electrical dynamic range, as measured through behavioral loudness scaling. Additionally, we compared eASSRs measured with the ∼40-pps stimulus and with a high-rate (500-pps) pulse train modulated in amplitude at rates around 40 Hz, and found that both showed similar recipient-specific effects of stimulation rate on response phase and amplitude. Our results highlight that neural responses to different electrical stimuli and at different central processing stages share common idiosyncratic properties, and support the validity of eASSRs for loudness-growth estimation in CI recipients.

Data available, click to request

Authors:

GARCIA, C., Sismono, F., GOEHRING, T., GUERIT, F., ARZOUNIAN, CARLYON, R.P.

Reference:

Year of publication:

2025

CBU number:

9177

Abstract:

The health of the auditory nerve is a key factor for hearing outcomes of cochlear-implant patients. Many electrophysiological markers of auditory-neural health have been proposed, with varying predictive power and independence from non-neural factors. The ‘Failure Index’, the ratio between stimulation current level and response magnitude of the electrically-evoked compound action potential (eCAP) was compared to the Panoramic eCAP method. Both methods predicted localized areas of reduced neural responsiveness in a group of human cochlear-implant users, but the Failure Index showed a greater dependence on a non-neural factor, namely the distances between the cochlear-implant electrodes and the auditory nerves. https://osf.io/pae78/

Data available, click to request

Authors:

Varga, D.K., RAYKOV, P.P., Jefferies, E., Ben-Yakov, A., Bird, C.M.

Reference:

Year of publication:

In Press

CBU number:

9176

Abstract:

Prediction errors drive learning by signalling mismatches between expectations and reality, but the neural systems supporting these computations remain debated. The hippocampus is implicated in mismatch detection, yet it is not known whether it signals mismatches with episodic memories or generalised knowledge. Across three fMRI experiments, we show that the hippocampus selectively responds to mismatches with episodic memories of specific events. In contrast, schematic mismatches engage Semantic Control and Multiple Demand Networks, as well as subcortical regions linked to prediction error signalling. Episodic mismatches also recruit the Default Mode Network. These findings challenge accounts that propose the hippocampus is a domain-general mismatch detector. Instead, the findings support a more specialised role for the hippocampus in learning that is underpinned by its well-established importance in processing episodic memories. https://osf.io/p6z2g

Data for this project is available at: https://osf.io/p6z2g

Authors:

RAYKOV, P.P., CORREIA, M., Tsvetanov, K., Henriques, R.N., Del Cerro-Leon, A., Bracher-Smith, M., Escott-Price, V., Raykov, Y.P., & HENSON, R.N.

Reference:

Year of publication:

In Press

CBU number:

9175

Abstract:

The microstructural and macrostructural integrity of white matter (WM) underpins efficient brain function, and is known to decline with age and vascular burden. Key aspects of WM health include axonal fibre density, myelination, free-water content, and the presence of tissue damage or lesions. Magnetic Resonance Imaging (MRI) offers multiple complementary sequences to non-invasively estimate these properties in vivo. For example, diffusion-weighted imaging (DWI) provides sensitive measures of microstructure, while T1-weighted and T2-weighted MRI can estimate total WM volume and hyper-intensities, and magnetisation transfer imaging (MT) and T1:T2 ratios can indicate myelin content. In this study, we leveraged all of these MRI-derived measures in a large population-based cohort (Cam-CAN) to identify latent WM factors and test how these factors relate to cardiovascular health and cognitive performance. Among 11 commonly-used WM metrics [Fractional Anisotropy (FA); Mean Signal Diffusion (MSD); Mean Signal Kurtosis (MSK); Neurite Density Index (NDI); fibre Orientation Dispersion Index (ODI); Free water volume faction (Fiso); spread of Mean Signal Diffusivity values (MSDvar); Magnetisation Transfer Ratio (MTR); T1:T2 ratio; volume of White Matter Hyper-Intensities (WMHI); White Matter Volume (WMV)], latent factor analysis showed that four factors were needed to explain 89% of the variance, which we interpreted in terms of 1) fibre density / myelination, 2) free-water / tissue damage, 3) fibre-crossing complexity and 4) microstructural complexity. These factors showed distinct effects of age and sex. To test the validity of these factors, we related them to measures of cardiovascular health and cognitive performance. Specifically, we ran path analyses linking 1) cardiovascular factors to the WM factors, and 2) the WM factors to cognitive measures. Even after adjusting for age and sex, we found that a vascular factor related to pulse pressure predicted the WM factor capturing free-water / tissue damage, and that several WM factors made unique predictions for fluid intelligence and processing speed. Our results show that there is both complementary and redundant information across common MR measures of WM, and their underlying latent factors may be useful for pinpointing the differential causes and contributions of white matter health in aging. https://osf.io/y7ct8/

Data available, click to request

Authors:

King, D., HENSON, R., CORREIA, M., ROWE, J., Cam-CAN, Tsvetanov, K.

Reference:

Year of publication:

2025

CBU number:

9172

Abstract:

BACKGROUND: In older adults, elevated pulse pressure predicts cognitive decline, independent of overall blood pressure. It is proposed to compromise cerebrovascular integrity, potentially leading to brain damage, though the underlying mechanisms remain unclear. We hypothesized that pulse pressure affects cognition by disrupting white matter microstructure, and that it does so independently of other cardiovascular risk factors. METHODS: Latent indices of pulse pressure, overall blood pressure and heart rate variability were estimated in a cross-sectional population-based cohort (n=708, aged 18-88 years). An indicator of white matter microstructure was derived from diffusion-weighted imaging, termed the “peak width of skeletonised mean diffusivity” (PSMD). Cognitive function was assessed using measures of processing speed. RESULTS: In robust multiple linear regression, pulse pressure was significantly associted with PSMD, with PSMD also being associated with processing speed. Thus higher pulse pressure was associated with greater white matter disruption, and greater white matter disruption was associated with slower processing abilities.This motivated testing whether PSMD mediates the effects of pulse pressure on processing speed. We tested this using structural equation models. PSMD mediated the effect of pulse pressure on processing speed, accounting for 72% of the effect after adjusting for age, and remained after adjusting for other cardiovascular factors. We then expanded the model to show that vascular-related changes in processing speed in turn drive changes in higher cognitive functions. CONCLUSIONS: High pulse pressure disrupts microstructural integrity of white matter in the brain, leading to slower processing speed. We propose that better management of pulse pressure could help to preserve white matter integrity and reduce cognitive decline in later life.

URL:

Data available, click to request

Authors:

Wolpe, N., Harlev, D., Bergmann, E., CamCAN, HENSON, R.

Reference:

Year of publication:

In Press

CBU number:

9171

Abstract:

Changes in emotion recognition are observed in ageing, in dementia, after brain lesions and as a function of mental health factors, such as depression. Older adults have been argued to show a ‘positivity bias’, which has been associated with a relatively spared recognition accuracy for positive emotion, and an increased tendency to label emotions as positive. This bias has been suggested to support mental well-being in ageing. However, it has also been found in association with cognitive decline and brain lesions. Here, we investigated the brain correlates of this age-related positivity bias. We used multimodal brain imaging in a large of human adults (n=665, 333 females) drawn from a population-derived cohort across the adult lifespan, together with a psychometric analysis of an emotion recognition task using facial expressions. Apart from overall reductions in expression recognition accuracy, older adults showed a notable pattern of increased perceptual thresholds for negative emotions and a reduced threshold for the positive emotion, even after accounting for general face recognition abilities. This positivity bias in labelling emotions was strongly associated with lower cognitive performance in older people, but not with (non-clinical) depressive symptoms. It was also associated with reduced grey matter volume in bilateral anterior hippocampus-amygdala, and increased functional connectivity between these regions and orbitofrontal cortex. Together, this age-related positivity bias is associated with cognitive decline and structural and functional brain differences. A positivity bias in emotion recognition may therefore reflect an early marker of neurodegeneration; a hypothesis that could be tested in future longitudinal studies. All data used for this work, including behavioural, structural, and functional imaging are publicly available upon signing data sharing agreement on https://cam-can.mrc-cbu.cam.ac.uk/dataset/. Code used to analyse the data and generate the figures is available on https://github.com/nwolpe/emotion_recognition

Data available, click to request

Authors:

VON SETH, J., ALLER, M., and DAVIS, M.H.

Reference:

Year of publication:

2025

CBU number:

9169

Abstract:

There are substantial individual differences in the benefit that can be obtained from visual cues during speech perception. Here, 113 normally hearing participants between the ages of 18 and 60 years old completed a three-part experiment investigating the reliability and predictors of individual audiovisual benefit for acoustically degraded speech. Audiovisual benefit was calculated as the relative intelligibility (at the individual-level) of approximately matched (at the group-level) auditory-only and audiovisual speech for materials at three levels of linguistic structure: meaningful sentences, monosyllabic words, and consonants in minimal syllables. This measure of audiovisual benefit was stable across sessions and materials, suggesting that a shared mechanism of audiovisual integration operates across levels of linguistic structure. Information transmission analyses suggested that this may be related to simple phonetic cue extraction: sentence-level audiovisual benefit was reliably predicted by the relative ability to discriminate place of articulation at the consonant-level. Finally, whereas unimodal speech perception was related to cognitive measures (matrix reasoning and vocabulary) and demographics (age and gender), audiovisual benefit was predicted only by unimodal speech perceptual abilities: Better lipreading ability and subclinically poorer hearing (speech reception thresholds) independently predicted enhanced audiovisual benefit. This work has implications for practices in quantifying audiovisual benefit and research identifying strategies to enhance multimodal communication in hearing loss.

URL:

Data available, click to request

Authors:

Knolle, F., Sterner, E.F., Demler, V.F., MACGREGOR, L.J., Mathys, C.

Reference:

Year of publication:

In Press

CBU number:

9168

Abstract:

Background: An imbalance in the weighting of prior beliefs and sensory evidence is thought to contribute to the development of psychotic symptoms, such as hallucinations and delusions. We investigated (1) how much individuals with schizotypal traits, a subclinical expression of psychosis-proneness, use high-level semantic priors and sensory evidence to understand noise-degraded language; (2) whether an imbalance would potentially result in task-based hallucinations – perceptions that match expectations but not the input; and finally (2) whether a potential imbalance was linked to altered levels of cortical glutamate. Methods: In a language comprehension task, we simultaneously manipulated semantic predictability, sensory degradation and surprisal to estimate the prior weight using a Bayesian Belief updating model. We conducted two studies. Study 1 (n=109) tested the language comprehension task behaviourally; study 2 (n=55) was used to replicate the findings of study 1; but was furthermore combined with 1H-Magnetresonance spectroscopy to assess cortical levels of glutamate. Results: Study 1 showed that high-level priors were overweighted with increasing schizotypy providing a potential explanation for the increased number of task-based hallucination observed in the same individuals. Importantly, study 2 (n=55), replicating the results of study 1, revealed that an overweighting of priors was associated with increased cingulate glutamate, providing a neurobiological basis for over-reliance on top-down predictions. Conclusion: These results offer a mechanistic and neurobiological understanding of how predictive coding alterations contribute to symptom development along the psychosis spectrum. https://osf.io/jts3k/

URL:

Data for this project is available at: https://osf.io/jts3k/

Authors:

MURPHY, F.C., DERMODY, N., WATSON, P., Scott, S.K., CALDER, A.J., PEERS, P.V., MANLY, T.

Reference:

Year of publication:

2025

CBU number:

9166

Abstract:

Frontal lobe lesions have been associated with executive impairments and changes in emotional/social function. Empirical studies using emotion recognition tasks in people with frontal lesions have indeed reported impairments that are predominantly associated with medial lesions. However, work has also identified a fronto-parietal 'multiple demand' (MD) network that is engaged in a wide variety of cognitive tasks. Previous studies have shown that fluid intelligence (IQ) scores, treated as a marker of MD function, completely account for deficits in some, but not all, tests of putatively separate executive functions. Here, a group of 39 participants with frontal lesions showed significant impairments (relative to age, sex and premorbid IQ-matched controls) on a measure of fluid IQ and 4 emotion recognition tasks. They also had higher levels of depression symptoms. Depression symptoms did not account for emotion task impairment. Fluid IQ completely accounted for the impairments in one 'emotion task' of inferring the emotion likely to be experienced in each of a series of vignettes. However, whilst fluid IQ was correlated with the other emotion measures (tests of categorising emotional expression from faces, eyes, and non-verbal vocalisations), significant variance was left unexplained. The significant intercorrelations between these residual scores was suggestive of a common 'non-fluid IQ' factor that may have an association with left lateral frontal lesions. The results are discussed in terms of the importance of identifying common general cognitive influences on tests of ostensibly specific functions in clinical assessments and research studies.

URL:

Data available, click to request