Biology subjects

Oestreich, L. K. L.

Publications and source records attributed to Oestreich, L. K. L..

3 recordsLinked to original sources

bioRxiv2018

White matter connectivity disruptions in the pre-clinical continuum of psychosis: A connectome study

BackgroundWidespread white matter disruptions in schizophrenia have been commonly reported, but it remains unanswered whether these abnormalities are associated with schizophrenia specifically or whether they range along a psychotic continuum into the healthy population. Investigating the extent of white matter connectivity disruptions specific to psychotic-like experiences in healthy individuals is insofar important as it is a necessary first step towards the development of prodromal psychosis biomarkers.\n\nMethodsHigh resolution, multi-shell diffusion-weighted magnetic resonance images were acquired from 89 healthy individuals. Whole-brain white matter fiber tracking was performed to quantify the strength of white matter connections. Network-based statistics were applied to white matter connections in a regression model in order to test for a linear relationship between streamline count and psychotic-like experiences.\n\nResultsA significant subnetwork was identified whereby streamline count declined with increasing quantity of psychotic-like experiences. This network of significant connectivity reductions affected all cortical lobes, subcortical structures and the cerebellum.\n\nConclusionA widespread network of linearly declining connectivity strength with increasing number of psychotic-like experiences was identified in healthy individuals. This finding is in line with white matter connectivity reductions reported from early to chronic stages of schizophrenia. We suggest that these white matter changes might be a potential biomarker for the identification of individuals at high risk for transitioning to psychosis.

neuroscience↗

bioRxiv2018

Structural connectivity facilitates functional connectivity of auditory prediction error generation within a fronto-temporal network

Auditory prediction errors, i.e. the mismatch between predicted and actual auditory input, are generated by a hierarchical functional network of cortical sources. This network is also interconnected by auditory white matter pathways. Hence it would be reasonable to assume that these structural and functional networks are quantitatively related, which is what the present study set out to investigate. Specifically, whether structural connectivity of auditory white matter pathways enables effective connectivity of auditory prediction error generation. Eighty-nine participants underwent diffusion weighted magnetic resonance imaging. Anatomically-constrained tractography was used to extract auditory white matter pathways, namely the bilateral arcuate fasciculus, the inferior occipito-frontal fasciculi (IOFF), and the auditory interhemispheric pathway, from which Apparent Fibre Density (AFD) was calculated. The same participants also underwent a stochastic oddball paradigm, which was used to elicit prediction error responses, while undergoing electroencephalographic recordings. Dynamic causal modelling (DCM) was used to investigate the effective connectivity of auditory prediction error generation in brain regions interconnected by the above mentioned auditory white matter pathways. Brain areas interconnected by all auditory white matter pathways best explained the dynamics of auditory prediction error responses. Furthermore, AFD in the right IOFF and right arcuate fasciculus significantly predicted the effective connectivity parameters underlying auditory prediction error generation. In conclusion, the generation of auditory prediction errors within an effectively connected, fronto-temporal network was found to be facilitated by the structural connectivity of auditory white matter pathways. These findings build upon the notion that structural connectivity facilitates dynamic interactions within brain regions that are effectively connected.\n\nSignificance statementThe brain continuously generates and updates hypotheses that predict forthcoming sensory input. Within the auditory domain, it has repeatedly been reported that these predictions about the auditory environment are facilitated by specific functional cortical connections. These functionally connected brain regions are also structurally connected via auditory white matter pathways. For the first time, this study provides quantitative evidence for a structural basis along which this functional network of auditory prediction error generation operates. This finding provides evidence for the notion that the functional connectivity of dynamically interacting brain areas is facilitated by structural connectivity amongst these brain areas.

neuroscience↗

bioRxiv2017

The functional anatomy of self-generated and predictable speech

Sensory attenuation refers to the cortical suppression of self-generated sensations relative to externally-generated sensations. This attenuation of cortical responsiveness is the result of internal forward models which make precise predictions about forthcoming sensations. Forward models of sensory attenuation in the auditory domain are thought to operate along auditory white matter pathways such as the arcuate fasciculus and the frontal aslant. The aim of this study was to investigate whether brain regions that are structurally connected via these white matter pathways are also effectively connected during overt speech, as well as as when listening to externally-generated speech that is temporally predictable via a visual cue. Using Electroencephalography (EEG) and Dynamic Causal Modelling (DCM) we investigated network models that link the primary auditory cortex to Wernickes and Brocas area either directly or indirectly through Geschwinds territory, which are structurally connected via the arcuate fasciculus. Connections between Brocas and supplementary motor area, which are structurally connected via the frontal aslant, were also included. Our results revealed that bilateral areas interconnected by indirect and direct pathways of the arcuate fasciculus, in addition to regions interconnected by the frontal aslant best explain the EEG responses to both self-generated speech, and speech that is externally-generated but temporally predictable. These findings indicate that structurally connected brain regions thought to be involved in auditory attenuation are also effectively connected. Critically, our findings expand on the notion of internal forward models, whereby sensory consequences of our actions are internally predicted and reflected in reduced cortical responsiveness to these sensations.\n\nHighlightsO_LIEffective connectivity of auditory attenuation to self-generated and predictable speech\nC_LIO_LIEEG and DCM were used to investigate several plausible network models\nC_LIO_LIStructurally connected brain areas of auditory attenuation are effectively connected\nC_LIO_LIInternal forward models modulate self-generated and predictable speech\nC_LI

neuroscience↗