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Gail A. Robinson

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

5 papers

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YNICL Journal 2024 Journal Article

Microstructural analysis does not support altered interhemispheric wiring of the human anterior commissure in corpus callosum dysgenesis

Timothy J. Edwards
Ryan J. Dean
Gail A. Robinson
Jacquelyn Knight
Simone A. Mandelstam
Linda J. Richards

BACKGROUND: Individuals with corpus callosum dysgenesis (CCD) lack the clear disconnection syndrome that is characteristic of individuals in whom the corpus callosum has been surgically severed. One potential explanation for this paradox is that the anterior commissure undergoes neuroplastic remodeling in CCD to improve interhemispheric communication between the brain hemispheres. METHODS: A cohort of sixteen individuals with CCD (and sixteen sex and age-matched neurotypical controls) underwent multi-shell diffusion magnetic resonance high-field imaging (dMRI) at 7-Tesla to assess the anatomy of the anterior commissure for evidence of neuroplasticity. RESULTS: No significant group-wise differences in midsagittal anterior commissure volumes were detected between the CCD and control cohorts, although there were CCD individuals within the cohort who exhibited volumes that were either substantially larger or smaller than their neurotypical counterparts. Axonal intracellular volume fractions were reduced across the CCD white matter, including regions of the anterior commissure, and tractographic analyses were unable to identify any novel connections projecting through the anterior commissure that were unique to CCD individuals. Finally, variances in the neuroanatomy of the anterior commissure in the CCD cohort did not correlate with performance on neuropsychological tasks that are highly dependent upon interhemispheric communication. CONCLUSIONS: The results of this study indicate that there are individuals within the CCD population in whom it is unlikely that the anterior commissure is the primary substrate for interhemispheric communication. Consequently, other, presently unknown, compensatory mechanisms are likely involved in supporting this function.

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YNIMG Journal 2023 Journal Article

Functional re-organization of hippocampal-cortical gradients during naturalistic memory processes

Léonie Borne
Ye Tian
Michelle K. Lupton
Johan N. van der Meer
Jayson Jeganathan
Bryan Paton
Nikitas Koussis
Christine C. Guo

The functional organization of the hippocampus mirrors that of the cortex, changing smoothly along connectivity gradients and abruptly at inter-areal boundaries. Hippocampal-dependent cognitive processes require flexible integration of these hippocampal gradients into functionally related cortical networks. To understand the cognitive relevance of this functional embedding, we acquired fMRI data while participants viewed brief news clips, either containing or lacking recently familiarized cues. Participants were 188 healthy mid-life adults and 31 adults with mild cognitive impairment (MCI) or Alzheimer's disease (AD). We employed a recently developed technique - connectivity gradientography - to study gradually changing patterns of voxel to whole brain functional connectivity and their sudden transitions. We observed that functional connectivity gradients of the anterior hippocampus map onto connectivity gradients across the default mode network during these naturalistic stimuli. The presence of familiar cues in the news clips accentuates a stepwise transition across the boundary from the anterior to the posterior hippocampus. This functional transition is shifted in the posterior direction in the left hippocampus of individuals with MCI or AD. These findings shed new light on the functional integration of hippocampal connectivity gradients into large-scale cortical networks, how these adapt with memory context and how these change in the presence of neurodegenerative disease.

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YNICL Journal 2021 Journal Article

A prospective cohort study of prodromal Alzheimer’s disease: Prospective Imaging Study of Ageing: Genes, Brain and Behaviour (PISA)

Michelle K. Lupton
Gail A. Robinson
Robert J. Adam
Stephen Rose
Gerard J. Byrne
Olivier Salvado
Nancy A. Pachana
Osvaldo P. Almeida

This prospective cohort study, "Prospective Imaging Study of Ageing: Genes, Brain and Behaviour" (PISA) seeks to characterise the phenotype and natural history of healthy adult Australians at high future risk of Alzheimer's disease (AD). In particular, we are recruiting midlife and older Australians with high and low genetic risk of dementia to discover biological markers of early neuropathology, identify modifiable risk factors, and establish the very earliest phenotypic and neuronal signs of disease onset. PISA utilises genetic prediction to recruit and enrich a prospective cohort and follow them longitudinally. Online surveys and cognitive testing are used to characterise an Australia-wide sample currently totalling over 3800 participants. Participants from a defined at-risk cohort and positive controls (clinical cohort of patients with mild cognitive impairment or early AD) are invited for onsite visits for detailed functional, structural and molecular neuroimaging, lifestyle monitoring, detailed neurocognitive testing, plus blood sample donation. This paper describes recruitment of the PISA cohort, study methodology and baseline demographics.

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YNIMG Journal 2020 Journal Article

Subthalamic deep brain stimulation identifies frontal networks supporting initiation, inhibition and strategy use in Parkinson's disease

Philip E. Mosley
Katherine Robinson
Terry Coyne
Peter Silburn
Megan S. Barker
Michael Breakspear
Gail A. Robinson
Alistair Perry

Initiation and inhibition are executive functions whose disruption in Parkinson's disease impacts substantially on everyday activities. Management of Parkinson's disease with subthalamic deep brain stimulation (DBS) modifies initiation and inhibition, with prior work suggesting that these effects may be mediated via the connectivity of the subthalamic nucleus (STN) with the frontal cortex. Here, we employed high-resolution structural neuroimaging to investigate the variability in initiation, inhibition and strategy use in a cohort of twenty-five (ten females, mean age 62. 5, mean Hoehn and Yahr stage 2. 5) participants undertaking subthalamic DBS for Parkinson's disease. Neuropsychological assessment of initiation and inhibition was performed preoperatively and at six months postoperatively. We first reconstructed the preoperative connectivity of the STN with a frontal network of anterior and superior medial cortical regions. We then modelled the postoperative site of subthalamic stimulation and reconstructed the connectivity of the stimulation field within this same network. We found that, at both pre- and postoperative intervals, inter-individual variability in inhibition and initiation were strongly associated with structural network connectivity. Measures of subcortical atrophy and local stimulation effects did not play a significant role. Preoperatively, we replicated prior work, including a role for the right inferior frontal gyrus in inhibition and strategy use, as well as the left inferior frontal gyrus in tasks requiring selection under conditions of maintained inhibition. Postoperatively, greater connectivity of the stimulation field with right anterior cortical regions was associated with greater rule violations and suppression errors, supporting prior work implicating right-hemispheric STN stimulation in disinhibition. Our findings suggest that, in Parkinson's disease, connectivity of the frontal cortex with the STN is an important mediator of individual variability in initiation and inhibition, . Personalised information on brain network architecture could guide individualised brain circuit manipulation to minimise neuropsychological disruption after STN-DBS.

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YNICL Journal 2019 Journal Article

Increased cognitive complexity reveals abnormal brain network activity in individuals with corpus callosum dysgenesis

Luke J. Hearne
Ryan J. Dean
Gail A. Robinson
Linda J. Richards
Jason B. Mattingley
Luca Cocchi

Cognitive reasoning is thought to require functional interactions between whole-brain networks. Such networks rely on both cerebral hemispheres, with the corpus callosum providing cross-hemispheric communication. Here we used high-field functional magnetic resonance imaging (7 T fMRI), a well validated cognitive task, and brain network analyses to investigate the functional networks underlying cognitive reasoning in individuals with corpus callosum dysgenesis (CCD), an anatomical abnormality that affects the corpus callosum. Participants with CCD were asked to solve cognitive reasoning problems while their brain activity was measured using fMRI. The complexity of these problems was parametrically varied by changing the complexity of relations that needed to be established between shapes within each problem matrix. Behaviorally, participants showed a typical reduction in task performance as problem complexity increased. Task-evoked neural activity was observed in brain regions known to constitute two key cognitive control systems: the fronto-parietal and cingulo-opercular networks. Under low complexity demands, network topology and the patterns of local neural activity in the CCD group closely resembled those observed in neurotypical controls. By contrast, when asked to solve more complex problems, participants with CCD showed a reduction in neural activity and connectivity within the fronto-parietal network. These complexity-induced, as opposed to resting-state, differences in functional network activity help resolve the apparent paradox between preserved network architecture found at rest in CCD individuals, and the heterogeneous deficits they display in response to cognitive task demands [preprint: https://doi.org/10.1101/312629].

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