ORCID Profile
0000-0001-7977-6693
Current Organisations
Turku Brain and Mind Center
,
Deakin University
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Publisher: Oxford University Press (OUP)
Date: 2023
DOI: 10.1093/BRAINCOMMS/FCAD105
Abstract: Tics are sudden stereotyped movements or vocalizations. Cases of lesion-induced tics are invaluable, allowing for causal links between symptoms and brain structures. While a lesion network for tics has recently been identified, the degree to which this network translates to Tourette syndrome has not been fully elucidated. This is important given that patients with Tourette syndrome make up a large portion of tic cases therefore, existing and future treatments should apply to these patients. The aim of this study was to first localize a causal network for tics from lesion-induced cases and then refine and validate this network in patients with Tourette syndrome. We independently performed ‘lesion network mapping’ using a large normative functional connectome (n = 1000) to isolate a brain network commonly connected to lesions causing tics (n = 19) identified through a systematic search. The specificity of this network to tics was assessed through comparison to lesions causing other movement disorders. Using structural brain coordinates from prior neuroimaging studies (n = 7), we then derived a neural network for Tourette syndrome. This was done using standard anatomical likelihood estimation meta-analysis and a novel method termed ‘coordinate network mapping’, which uses the same coordinates, yet maps their connectivity using the aforementioned functional connectome. Conjunction analysis was used to refine the network for lesion-induced tics to Tourette syndrome by identifying regions common to both lesion and structural networks. We then tested whether connectivity from this common network is abnormal in a separate resting-state functional connectivity MRI data set from idiopathic Tourette syndrome patients (n = 21) and healthy controls (n = 25). Results showed that lesions causing tics were distributed throughout the brain however, consistent with a recent study, these were part of a common network with predominant basal ganglia connectivity. Using conjunction analysis, coordinate network mapping findings refined the lesion network to the posterior putamen, caudate nucleus, globus pallidus externus (positive connectivity) and precuneus (negative connectivity). Functional connectivity from this positive network to frontal and cingulate regions was abnormal in patients with idiopathic Tourette syndrome. These findings identify a network derived from lesion-induced and idiopathic data, providing insight into the pathophysiology of tics in Tourette syndrome. Connectivity to our cortical cluster in the precuneus offers an exciting opportunity for non-invasive brain stimulation protocols.
Publisher: Cold Spring Harbor Laboratory
Date: 13-04-2022
DOI: 10.1101/2022.04.11.22273755
Abstract: Parkinsonism is a feature of several neurodegenerative disorders, including Parkinson’s disease (PD), progressive supranuclear palsy (PSP), corticobasal degeneration syndrome (CBS) and multiple system atrophy (MSA). Neuroimaging studies have yielded insights into parkinsonism however it remains unclear whether there is a common neural substrate amongst disorders. The aim of the present meta-analysis was to identify consistent brain alterations in parkinsonian disorders (PD, PSP, CBS, MSA) both in idually, and combined, to elucidate the shared substrate of parkinsonism. 33,505 studies were systematically screened following searches of MEDLINE Complete and Embase databases. A series of whole-brain activation likelihood estimation meta-analyses were performed on 126 neuroimaging studies (64 PD 25 PSP 18 CBS 19 MSA) utilizing anatomical MRI, perfusion or metabolism positron emission tomography and single photon emission computed tomography. Abnormality of the caudate, thalamus, middle frontal and temporal gyri was common to all parkinsonian disorders. Localizations of commonly affected brain regions in in idual disorders aligned with current diagnostic imaging markers, localizing the midbrain in PSP, putamen in MSA-parkinsonian variant and brainstem in MSA-cerebellar variant. Regions of the basal ganglia and precuneus were most commonly affected in PD, while CBS was characterized by caudate abnormality. To our knowledge, this is the largest meta-analysis of neuroimaging studies in parkinsonian disorders. Findings support the notion that parkinsonism may share a common neural substrate, independent of the underlying disease process, while also highlighting characteristic patterns of brain abnormality in each disorder.
Publisher: Oxford University Press (OUP)
Date: 2023
DOI: 10.1093/BRAINCOMMS/FCAD172
Abstract: Parkinsonism is a feature of several neurodegenerative disorders, including Parkinson’s disease, progressive supranuclear palsy, corticobasal syndrome and multiple system atrophy. Neuroimaging studies have yielded insights into parkinsonian disorders however, due to variability in results, the brain regions consistently implicated in these disorders remain to be characterized. The aim of this meta-analysis was to identify consistent brain abnormalities in in idual parkinsonian disorders (Parkinson’s disease, progressive supranuclear palsy, corticobasal syndrome and multiple system atrophy) and to investigate any shared abnormalities across disorders. A total of 44 591 studies were systematically screened following searches of two databases. A series of whole-brain activation likelihood estimation meta-analyses were performed on 132 neuroimaging studies (69 Parkinson’s disease 23 progressive supranuclear palsy 17 corticobasal syndrome and 23 multiple system atrophy) utilizing anatomical MRI, perfusion or metabolism PET and single-photon emission computed tomography. Meta-analyses were performed in each parkinsonian disorder within each imaging modality, as well as across all included disorders. Results in progressive supranuclear palsy and multiple system atrophy aligned with current imaging markers for diagnosis, encompassing the midbrain, and brainstem and putamen, respectively. PET imaging studies of patients with Parkinson’s disease most consistently reported abnormality of the middle temporal gyrus. No significant clusters were identified in corticobasal syndrome. When examining abnormalities shared across all four disorders, the caudate was consistently reported in MRI studies, whilst the thalamus, inferior frontal gyrus and middle temporal gyri were commonly implicated by PET. To our knowledge, this is the largest meta-analysis of neuroimaging studies in parkinsonian disorders and the first to characterize brain regions implicated across parkinsonian disorders.
Publisher: Springer Science and Business Media LLC
Date: 02-04-2022
DOI: 10.1007/S11682-022-00655-4
Abstract: Recent neuroimaging studies have reported alterations in brain activation during cognitive tasks in cancer patients who have undergone chemotherapy treatment. However, the location of these altered brain activation patterns after chemotherapy varies considerably across studies. The aim of the present meta-analysis was to quantitatively synthesise this body of evidence using Activation Likelihood Estimation to identify reliable regions of altered brain activation in cancer patients treated with chemotherapy, compared to healthy controls and no chemotherapy controls. Our systematic search identified 12 studies that adopted task-related fMRI on non-central nervous system cancer patients who received chemotherapy relative to controls. All studies were included in the analyses and were grouped into four contrasts. Cancer patients treated with chemotherapy showed reduced activation in the left superior parietal lobe recuneus (family-wise error corrected p .05) compared to no chemotherapy controls. No significant clusters were found in three of our contrasts. The majority of studies did not support an association between altered brain activation and cognitive performance after chemotherapy. Findings point towards a possible chemotherapy-induced alteration, which could inform targeted treatment strategies. With continued work in this field using homogenous task-related protocols and cancer populations, fMRI may be used as a biomarker of cognitive deficits in the future.
No related grants have been discovered for Elizabeth Ellis.