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Philip McGuire

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YNIMG Journal 2022 Journal Article

Reliability of structural MRI measurements: The effects of scan session, head tilt, inter-scan interval, acquisition sequence, FreeSurfer version and processing stream

  • Emily P Hedges
  • Mihail Dimitrov
  • Uzma Zahid
  • Barbara Brito Vega
  • Shuqing Si
  • Hannah Dickson
  • Philip McGuire
  • Steven Williams

BACKGROUND: Large-scale longitudinal and multi-centre studies are used to explore neuroimaging markers of normal ageing, and neurodegenerative and mental health disorders. Longitudinal changes in brain structure are typically small, therefore the reliability of automated techniques is crucial. Determining the effects of different factors on reliability allows investigators to control those adversely affecting reliability, calculate statistical power, or even avoid particular brain measures with low reliability. This study examined the impact of several image acquisition and processing factors and documented the test-retest reliability of structural MRI measurements. METHODS: In Phase I, 20 healthy adults (11 females; aged 20-30 years) were scanned on two occasions three weeks apart on the same scanner using the ADNI-3 protocol. On each occasion, individuals were scanned twice (repetition), after re-entering the scanner (reposition) and after tilting their head forward. At one year follow-up, nine returning individuals and 11 new volunteers were recruited for Phase II (11 females; aged 22-31 years). Scans were acquired on two different scanners using the ADNI-2 and ADNI-3 protocols. Structural images were processed using FreeSurfer (v5.3.0, 6.0.0 and 7.1.0) to provide subcortical and cortical volume, cortical surface area and thickness measurements. Intra-class correlation coefficients (ICC) were calculated to estimate test-retest reliability. We examined the effect of repetition, reposition, head tilt, time between scans, MRI sequence and scanner on reliability of structural brain measurements. Mean percentage differences were also calculated in supplementary analyses. RESULTS: Using the FreeSurfer v7.1.0 longitudinal pipeline, we observed high reliability for subcortical and cortical volumes, and cortical surface areas at repetition, reposition, three weeks and one year (mean ICCs>0.97). Cortical thickness reliability was lower (mean ICCs>0.82). Head tilt had the greatest adverse impact on ICC estimates, for example reducing mean right cortical thickness to ICC=0.74. In contrast, changes in ADNI sequence or MRI scanner had a minimal effect. We observed an increase in reliability for updated FreeSurfer versions, with the longitudinal pipeline consistently having a higher reliability than the cross-sectional pipeline. DISCUSSION: Longitudinal studies should monitor or control head tilt to maximise reliability. We provided the ICC estimates and mean percentage differences for all FreeSurfer brain regions, which may inform power analyses for clinical studies and have implications for the design of future longitudinal studies.

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YNICL Journal 2020 Journal Article

Resting state fMRI based multilayer network configuration in patients with schizophrenia

  • George Gifford
  • Nicolas Crossley
  • Matthew J Kempton
  • Sarah Morgan
  • Paola Dazzan
  • Jonathan Young
  • Philip McGuire

Novel methods for measuring large-scale dynamic brain organisation are needed to provide new biomarkers of schizophrenia. Using a method for modelling dynamic modular organisation (Mucha et al., 2010), evidence suggests higher 'flexibility' (switching between multilayer network communities) to be a feature of schizophrenia (Braun et al., 2016). The current study compared flexibility between 55 patients with schizophrenia and 72 controls (the COBRE Dataset). In addition, novel methods of 'between resting state network synchronisation' (BRSNS) and the probability of transition from one community to another were used to further describe group differences in dynamic community structure. There was significantly higher schizophrenia group flexibility scores in cerebellar (F (1124) = 9.33, p (FDR) = 0.017), subcortical (F (1124) = 13.14, p (FDR) = 0.005), and fronto-parietal task control (F (1124) = 7.19, p (FDR) = 0.033) resting state networks (RSNs), as well as in the left thalamus (MNI XYZ: -2, -13, 12; F(1, 124) = 17.1, p (FDR) < 0.001) and the right crus I (MNI XYZ: 35, -67, -34; F (1, 124) = 19.65, p (FDR) < 0.001). Flexibility in the left thalamus reflected transitions between communities covering default mode and sensory-somatomotor RSNs. BRSNS scores suggested altered dynamic inter-RSN modular configuration in schizophrenia. This study suggests less stable community structure in a schizophrenia group at an RSN and node level and provides novel methods of exploring dynamic community structure. Mediation of group differences by mean time window correlation did however suggest flexibility to be no better as a schizophrenia biomarker than simpler measures and a range of methodological choices affected results.

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YNICL Journal 2017 Journal Article

Meta-analysis of associations between childhood adversity and hippocampus and amygdala volume in non-clinical and general population samples

  • Maria Calem
  • Konstantinos Bromis
  • Philip McGuire
  • Craig Morgan
  • Matthew J Kempton

BACKGROUND: Studies of psychiatric populations have reported associations between childhood adversity and volumes of stress-related brain structures. This meta-analysis investigated these associations in non-clinical samples and therefore independent of the effects of severe mental health difficulties and their treatment. METHODS: The MEDLINE database was searched for magnetic resonance imaging studies measuring brain structure in adults with and without childhood adversity. Fifteen eligible papers (1781 participants) reporting hippocampal volumes and/or amygdala volumes were pooled using a random effects meta-analysis. RESULTS: = 0.124). This association differed depending on whether studies included participants with some psychopathology, though this may be due to differences in the type of adversity these studies examined. There was no strong evidence of any differences in amygdala volume. DISCUSSION: Childhood adversity may have only a modest impact on stress-related brain structures in those without significant mental health difficulties.

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YNIMG Journal 2017 Journal Article

Using neuroimaging to help predict the onset of psychosis

  • George Gifford
  • Nicolas Crossley
  • Paolo Fusar-Poli
  • Hugo G. Schnack
  • René S. Kahn
  • Nikolaos Koutsouleris
  • Tyrone D. Cannon
  • Philip McGuire

The aim of this review is to assess the potential for neuroimaging measures to facilitate prediction of the onset of psychosis. Research in this field has mainly involved people at ‘ultra-high risk’ (UHR) of psychosis, who have a very high risk of developing a psychotic disorder within a few years of presentation to mental health services. The review details the key findings and developments in this area to date and examines the methodological and logistical challenges associated with making predictions in an individual subject in a clinical setting.

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YNICL Journal 2016 Journal Article

Corticolimbic dysfunction during facial and prosodic emotional recognition in first-episode psychosis patients and individuals at ultra-high risk

  • Huai-Hsuan Tseng
  • Jonathan P. Roiser
  • Gemma Modinos
  • Irina Falkenberg
  • Carly Samson
  • Philip McGuire
  • Paul Allen

Emotional processing dysfunction is widely reported in patients with chronic schizophrenia and first-episode psychosis (FEP), and has been linked to functional abnormalities of corticolimbic regions. However, corticolimbic dysfunction is less studied in people at ultra-high risk for psychosis (UHR), particularly during processing prosodic voices. We examined corticolimbic response during an emotion recognition task in 18 UHR participants and compared them with 18 FEP patients and 21 healthy controls (HC). Emotional recognition accuracy and corticolimbic response were measured during functional magnetic resonance imaging (fMRI) using emotional dynamic facial and prosodic voice stimuli. Relative to HC, both UHR and FEP groups showed impaired overall emotion recognition accuracy. Whilst during face trials, both UHR and FEP groups did not show significant differences in brain activation relative to HC, during voice trials, FEP patients showed reduced activation across corticolimbic networks including the amygdala. UHR participants showed a trend for increased response in the caudate nucleus during the processing of emotionally valenced prosodic voices relative to HC. The results indicate that corticolimbic dysfunction seen in FEP patients is also present, albeit to a lesser extent, in an UHR cohort, and may represent a neural substrate for emotional processing difficulties prior to the onset of florid psychosis.

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YNICL Journal 2016 Journal Article

Volumetric, relaxometric and diffusometric correlates of psychotic experiences in a non-clinical sample of young adults

  • Mark Drakesmith
  • Anirban Dutt
  • Leon Fonville
  • Stanley Zammit
  • Abraham Reichenberg
  • C. John Evans
  • Philip McGuire
  • Glyn Lewis

BACKGROUND: Grey matter (GM) abnormalities are robust features of schizophrenia and of people at ultra high-risk for psychosis. However the extent to which neuroanatomical alterations are evident in non-clinical subjects with isolated psychotic experiences is less clear. METHODS: Individuals (mean age 20 years) with (n = 123) or without (n = 125) psychotic experiences (PEs) were identified from a population-based cohort. All underwent T1-weighted structural, diffusion and quantitative T1 relaxometry MRI, to characterise GM macrostructure, microstructure and myelination respectively. Differences in quantitative GM structure were assessed using voxel-based morphometry (VBM). Binary and ordinal models of PEs were tested. Correlations between socioeconomic and other risk factors for psychosis with cortical GM measures were also computed. RESULTS: GM volume in the left supra-marginal gyrus was reduced in individuals with PEs relative to those with no PEs. The greater the severity of PEs, the greater the reduction in T1 relaxation rate (R1) across left temporoparietal and right pre-frontal cortices. In these regions, R1 was positively correlated with maternal education and inversely correlated with general psychopathology. CONCLUSIONS: PEs in non-clinical subjects were associated with regional reductions in grey-matter volume reduction and T1 relaxation rate. The alterations in T1 relaxation rate were also linked to the level of general psychopathology. Follow up of these subjects should clarify whether these alterations predict the later development of an ultra high-risk state or a psychotic disorder.

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YNIMG Journal 2015 Journal Article

Decreased centrality of subcortical regions during the transition to adolescence: A functional connectivity study

  • João Ricardo Sato
  • Giovanni Abrahão Salum
  • Ary Gadelha
  • Gilson Vieira
  • André Zugman
  • Felipe Almeida Picon
  • Pedro Mario Pan
  • Marcelo Queiroz Hoexter

Investigations of brain maturation processes are a key step to understand the cognitive and emotional changes of adolescence. Although structural imaging findings have delineated clear brain developmental trajectories for typically developing individuals, less is known about the functional changes of this sensitive development period. Developmental changes, such as abstract thought, complex reasoning, and emotional and inhibitory control, have been associated with more prominent cortical control. The aim of this study is to assess brain networks connectivity changes in a large sample of 7- to 15-year-old subjects, testing the hypothesis that cortical regions will present an increasing relevance in commanding the global network. Functional magnetic resonance imaging (fMRI) data were collected in a sample of 447 typically developing children from a Brazilian community sample who were submitted to a resting state acquisition protocol. The fMRI data were used to build a functional weighted graph from which eigenvector centrality (EVC) was extracted. For each brain region (a node of the graph), the age-dependent effect on EVC was statistically tested and the developmental trajectories were estimated using polynomial functions. Our findings show that angular gyrus become more central during this maturation period, while the caudate; cerebellar tonsils, pyramis, thalamus; fusiform, parahippocampal and inferior semilunar lobe become less central. In conclusion, we report a novel finding of an increasing centrality of the angular gyrus during the transition to adolescence, with a decreasing centrality of many subcortical and cerebellar regions.

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YNICL Journal 2012 Journal Article

Functional brain networks before the onset of psychosis: A prospective fMRI study with graph theoretical analysis

  • Louis-David Lord
  • Paul Allen
  • Paul Expert
  • Oliver Howes
  • Matthew Broome
  • Renaud Lambiotte
  • Paolo Fusar-Poli
  • Isabel Valli

Individuals with an at-risk mental state (ARMS) have a risk of developing a psychotic disorder significantly greater than the general population. However, it is not currently possible to predict which ARMS individuals will develop psychosis from clinical assessment alone. Comparison of ARMS subjects who do, and do not, develop psychosis can reveal which factors are critical for the onset of illness. In the present study, 37 patients with an ARMS were followed clinically at least 24 months subsequent to initial referral. Functional MRI data were collected at the beginning of the follow-up period during performance of an executive task known to recruit frontal lobe networks and to be impaired in psychosis. Graph theoretical analysis was used to compare the organization of a functional brain network in ARMS patients who developed a psychotic disorder following the scan (ARMS-T) to those who did not become ill during the same follow-up period (ARMS-NT) and aged-matched controls. The global properties of each group's representative network were studied (density, efficiency, global average path length) as well as regionally-specific contributions of network nodes to the organization of the system (degree, farness-centrality, betweenness-centrality). We focused our analysis on the dorsal anterior cingulate cortex (ACC), a region known to support executive function that is structurally and functionally impaired in ARMS patients. In the absence of between-group differences in global network organization, we report a significant reduction in the topological centrality of the ACC in the ARMS-T group relative to both ARMS-NT and controls. These results provide evidence that abnormalities in the functional organization of the brain predate the onset of psychosis, and suggest that loss of ACC topological centrality is a potential biomarker for transition to psychosis.

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YNIMG Journal 2011 Journal Article

Characterization of the anterior cingulate's role in the at-risk mental state using graph theory

  • Louis-David Lord
  • Paul Allen
  • Paul Expert
  • Oliver Howes
  • Renaud Lambiotte
  • Philip McGuire
  • Subrata K. Bose
  • Samuel Hyde

The onset of positive symptoms in schizophrenia is often preceded by a prodromal phase characterized by neurocognitive abnormalities as well as changes in brain structure and function. Increasing efforts have been made to identify individuals at elevated risk of developing schizophrenia, as early intervention may help prevent progression towards psychosis. The present study uses functional MRI and graph theoretical analysis to characterize the organization of a functional brain network in at-risk mental state patients with varying symptoms assessed with the PANSS and healthy volunteers during performance of a verbal fluency task known to recruit frontal lobe networks and to be impaired in psychosis. We first examined between-groups differences in total network connectivity and global network compactness/efficiency. We then addressed the role of specific brain regions in the network organization by calculating the node-specific "betweeness centrality", "degree centrality" and "local average path length" metrics; different ways of assessing a region's importance in a network. We focused our analysis on the anterior cingulate cortex (ACC); a region known to support executive function that is structurally and functionally impaired in at-risk mental state patients. Although global network connectivity and efficiency were maintained in at-risk patients relative to the controls, we report a significant decrease in the contribution of the ACC to task-relevant network organization in at risk subjects with elevated symptoms (PANSS ≥ 45) relative to both the controls and the less symptomatic at-risk subjects, as reflected by a reduction in the topological centrality of the ACC. These findings provide evidence of network abnormalities and anterior cingulate cortex dysfunction in people with prodromal signs of schizophrenia.

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YNIMG Journal 2011 Journal Article

COMT gene polymorphism and corpus callosum morphometry in preterm born adults

  • Anirban Dutt
  • Madiha Shaikh
  • Taposhri Ganguly
  • Chiara Nosarti
  • Muriel Walshe
  • Maria Arranz
  • Larry Rifkin
  • Colm McDonald

Introduction Preterm birth is associated with a range of neurodevelopmental deficits, including corpus callosum (CC) abnormalities, which persist into late adolescence and early adulthood. A common single-nucleotide polymorphism in the catechol-o-methyl transferase (COMT) gene (Val158Met) is associated with cognition and brain structure and may play a role in neurodevelopment. It is not known whether this polymorphism is associated with CC morphometry in individuals born preterm. Methods Structural MRI scans were acquired in 33 adults born very preterm (before 33 weeks' gestation) and 29 healthy controls. DNA was collected and COMT Val158Met polymorphism status determined using standard available assays. The mid-sagittal area of four antero-posterior subdivisions of the CC was measured. The effect of COMT Val158Met polymorphism on cross-sectional CC areas was studied using multivariate analysis and generalised linear models, adjusted for the effects of the clinical sample group (preterm vs. control), age and sex. Results The COMT Val/Val homozygous genotype was observed to be significantly associated with reduced size of the total corpus callosum, and this relationship was present for the anterior, midposterior and posterior quarters of the CC. Conclusions The COMT Val158Met polymorphism possibly influences the morphometry of the corpus callosum associated with very preterm births. Further studies with larger sample sizes are warranted to conclusively establish the effects of individual genotypes of the COMT gene on corpus callosum in preterm born adults.

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YNIMG Journal 2011 Journal Article

Differential effects of DAAO on regional activation and functional connectivity in schizophrenia, bipolar disorder and controls

  • Sergio Alessandro Papagni
  • Andrea Mechelli
  • Diana P. Prata
  • Joseph Kambeitz
  • Cynthia H.Y. Fu
  • Marco Picchioni
  • Muriel Walshe
  • Timothea Toulopoulou

Recent studies have identified DAAO as a probable susceptibility gene for schizophrenia and bipolar disorder. However, little is known about how this gene affects brain function to increase vulnerability to these disorders. We examined the impact of DAAO genotype (rs3918346) on brain function in patients with schizophrenia, patients with bipolar I disorder and healthy controls. We tested the hypothesis that a variation in DAAO genotype would be associated with altered prefrontal function and altered functional connectivity in schizophrenia and bipolar disorder. We used functional magnetic resonance imaging to measure brain responses during a verbal fluency task in a total of 121 subjects comprising 40 patients with schizophrenia, 33 patients with bipolar disorder and 48 healthy volunteers. We then used statistical parametric mapping (SPM) and psycho-physiological interaction (PPI) analyses to estimate the main effects of diagnostic group, the main effect of genotype, and their interaction on brain activation and on functional connectivity. Inferences were made at p<0. 05, after correction for multiple comparisons across the whole brain. In the schizophrenia group relative to the control group, patients with one or two copies of the T allele showed lower deactivation in the left precuneus and greater activation in the right posterior cingulate gyrus than patients with two copies of the C allele. This diagnosis×genotype interaction was associated with differences in the functional connectivity of these two regions with other cortical and subcortical areas. In contrast, there were no significant effects of diagnosis or of genotype in comparisons involving bipolar patients. Our results suggest that genetic variation in DAAO has a significant impact on both regional activation and functional connectivity, and provide evidence for a diagnosis-dependent pattern of gene action.

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YNIMG Journal 2011 Journal Article

Gray matter alterations related to P300 abnormalities in subjects at high risk for psychosis: Longitudinal MRI-EEG study

  • Paolo Fusar-Poli
  • Nicolas Crossley
  • James Woolley
  • Francesco Carletti
  • Rocio Perez-Iglesias
  • Matthew Broome
  • Louise Johns
  • Paul Tabraham

Background Psychotic disorders are characterized by gray matter and volumetric and electrophysiological abnormalities. The relationship between these factors in the onset of psychotic illness is unclear. Methods Eighty English-native right-handed subjects (39 subjects at ultra high risk for psychosis “ARMS” and 41 healthy volunteers) were scanned with MRI, and studied using EEG during an oddball task. Both assessments were performed at first clinical presentation. The ARMS subjects were then followed clinically, with the MRI and EEG assessments repeated in a subgroup of each sample. Results The P300 amplitude at presentation was significantly lower in the ARMS subjects than in controls. At baseline, the ARMS group showed reduced gray matter volume relative to controls in the right superior frontal gyrus, left medial frontal gyrus, left inferior frontal gyrus, right orbital gyrus and right supramarginal gyrus. Transition to psychosis (26%) was associated with reduced gray matter in the right inferior parietal lobule and in the left parahippocampal gyrus. Within the ARMS group, there was a positive correlation between P300 amplitude and gray matter volume in the right supramarginal gyrus. A significant group by P300 by gray matter interaction was detected in the left medial frontal gyrus. Longitudinal assessment revealed progressive gray matter alterations in prefrontal and subcortical areas of the ARMS but no significant changes in P300 amplitude over time. Conclusions P300 abnormalities in the ARMS are related to alterations in regional gray matter volume and represent a correlate of an increased vulnerability to psychosis.

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YNIMG Journal 2011 Journal Article

Prognostic prediction of therapeutic response in depression using high-field MR imaging

  • Qiyong Gong
  • Qizhu Wu
  • Cristina Scarpazza
  • Su Lui
  • Zhiyun Jia
  • Andre Marquand
  • Xiaoqi Huang
  • Philip McGuire

Despite significant advances in the treatment of major depression, there is a high degree of variability in how patients respond to treatment. Approximately 70% of patients show some improvement following standard antidepressant treatment and are classified as having non-refractory depressive disorder (NDD), while the remaining 30% of patients do not respond to treatment and are classified as having refractory depressive disorder (RDD). At present, there are no objective, neurological markers which can be used to identify individuals with depression and predict clinical outcome. We therefore examined the diagnostic and prognostic potential of pre-treatment structural neuroanatomy using support vector machine (SVM). Sixty-one drug-naïve adults suffering from depression and 42 healthy volunteers were scanned using structural magnetic resonance imaging (sMRI). Patients then received standard antidepressant medication (either tricyclic, typical serotonin–norepinephrine reuptake inhibitor or typical selective serotonin reuptake inhibitor). Based on clinical outcome, we selected two groups of RDD (n =23) and NDD (n =23) patients matched for age, sex and pre-treatment severity of depression. Diagnostic accuracy of gray matter was 67. 39% for RDD (p =0. 01) and 76. 09% for NDD (p <0. 001), while diagnostic accuracy of white matter was 58. 70% for RDD (p =0. 13) and 84. 65% for NDD (p <0. 001). SVM applied to gray matter correctly distinguished between RDD and NDD patients with an accuracy of 69. 57% (p =0. 006); in contrast, SVM applied to white matter predicted clinical outcome with an accuracy of 65. 22% (p =0. 02). These results indicate that both gray and white matter have diagnostic and prognostic potential in major depression and may provide an initial step towards the use of biological markers to inform clinical treatment. Future studies will benefit from the integration of structural neuroimaging with other imaging modalities as well as genetic, clinical and cognitive information.

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YNIMG Journal 2010 Journal Article

Cingulate activity and fronto-temporal connectivity in people with prodromal signs of psychosis

  • Paul Allen
  • Klaas E. Stephan
  • Andrea Mechelli
  • Fern Day
  • Nicholas Ward
  • Jeffery Dalton
  • Steven C. Williams
  • Philip McGuire

Schizophrenia is associated with fronto-temporal dysconnectivity, but it is not clear whether this is a risk factor for the disorder or is a consequence of the established illness. The aim of the present study was to use fMRI to investigate fronto-temporal connectivity in subjects with prodromal signs of schizophrenia using the Hayling Sentence Completion Task (HSCT). Thirty participants, 15 with an at risk mental state (ARMS) and 15 healthy controls were scanned whilst completing 80 sentence stems. The congruency and constraint of sentences varied across trials. Dynamic causal modelling (DCM) and Bayesian model selection (BMS) were used to compare alternative models of connectivity in a task related network. During the HSCT ARMS subjects did not differ from Healthy Controls in terms of fronto-temporal activation, i. e. there was neither a main effect of group nor a group-by-task interaction. However, there was both a significant main effect of group and a significant interaction in the anterior cingulate cortex (ACC), with greater ACC activity in the ARMS subjects. A systematic BMS procedure among 14 alternative DCMs including the ACC, middle frontal, and middle temporal gyri revealed intact task-dependent modulation of fronto-temporal effective connectivity in the ARMS group. However, ARMS subjects showed increased endogenous connection strength between the ACC and the middle temporal gyrus relative to healthy controls. Although task related fronto-temporal integration in the ARMS was intact, this may depend on increased engagement of the ACC which was not observed in healthy control subjects.

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YNIMG Journal 2010 Journal Article

The test–retest reliability of 18F-DOPA PET in assessing striatal and extrastriatal presynaptic dopaminergic function

  • Alice Egerton
  • Arsime Demjaha
  • Philip McGuire
  • Mitul A. Mehta
  • Oliver D. Howes

Brain presynaptic dopaminergic function can be assessed using 18F-DOPA positron emission tomography (PET). Regional 18F-DOPA utilization may be used to index dopaminergic abnormalities over time or dopaminergic response to treatment in clinical populations. Such studies require prior knowledge of the stability of the 18F-DOPA signal in the brain regions of interest. Test–retest reliability was examined in eight healthy volunteers who each received two 18F-DOPA PET scans, approximately 2 years apart. 18F-DOPA utilization (k i cer) was determined using graphical analysis relative to a reference tissue input (Patlak and Blasberg, 1985). Reproducibility (measured as the within-subjects variation) and reliability (measured as intraclass correlation coefficients, ICCs) of 18F-DOPA k i cer were assessed in the structural and functional subdivisions of the striatum and select extrastriatal brain regions. Voxel-based median ICC maps were used to visualize the distribution of 18F-DOPA k i cer reliability across the brain. The caudate and putamen, and associative and sensorimotor, striatal subdivisions showed good reliability across the two scan sessions with bilateral ICCs ranging from 0. 681 to 0. 944. Reliability was generally lower in extrastriatal regions, with bilateral ICCs ranging from 0. 235 in the amygdala to 0. 894 in the thalamus. These data confirm the utility of 18F-DOPA PET in assessing dopaminergic function in the striatum and select extrastriatal areas but highlight the limitations in using this approach to measure dopaminergic function in low uptake extrastriatal brain areas. This information can be used to optimize the experimental design of future studies investigating changes in brain dopaminergic function with 18F-DOPA.

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YNIMG Journal 2009 Journal Article

Neural substrates of visual paired associates in young adults with a history of very preterm birth: Alterations in fronto-parieto-occipital networks and caudate nucleus

  • Ana Narberhaus
  • Emma Lawrence
  • Matthew P. Allin
  • Muriel Walshe
  • Philip McGuire
  • Larry Rifkin
  • Robin Murray
  • Chiara Nosarti

This study investigated neuronal activation during visuo-perceptual learning processing in adults who were born very preterm (VPT, <33 weeks' gestation). A visual paired associates task was administered during functional magnetic resonance imaging (fMRI) and neuronal activation was compared between 21 VPT-born adults of both sexes and 22 matched controls. The task consisted of 4 conditions (encoding, recognition, same/different discrimination condition (baseline) and a low-level baseline), each containing 8 stimuli pairs. There were no group differences in terms of correctly recognized visual pairs. However, during encoding, VPT-born individuals showed increased BOLD signal response compared to controls in left caudate nucleus, right cuneus (BA 18) and left superior parietal lobule (BA 7), and decreased signal in right inferior frontal gyrus (BA 46). During recognition, VPT-born adults showed increased BOLD signal response compared to controls in right cerebellum and in anterior cingulate gyrus (BA 32) bilaterally. The fMRI data were additionally analyzed controlling for structural differences in the hippocampus bilaterally, where the VPT group showed decreased probability of the absolute amount of grey matter compared to controls. Results of our study suggest that despite good task performance, VPT-born individuals activate different neural networks during mnemonic processing of visuo-perceptual material which may indicate neural compensation for the adult consequences of perinatal brain injury following very preterm birth, as well as maturational delays.

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YNIMG Journal 2008 Journal Article

Abnormal P300 in people with high risk of developing psychosis

  • Elvira Bramon
  • Madiha Shaikh
  • Matthew Broome
  • Julia Lappin
  • Daniel Bergé
  • Fern Day
  • James Woolley
  • Paul Tabraham

Background Individuals with an “at-risk mental state” (or “prodromal” symptoms) have a 20–40% chance of developing psychosis; however it is difficult to predict which of them will become ill on the basis of their clinical symptoms alone. We examined whether neurophysiological markers could help to identify those who are particularly vulnerable. Method 35 cases meeting PACE criteria for the at-risk mental state (ARMS) and 57 controls performed an auditory oddball task whilst their electroencephalogram was recorded. The latency and amplitude of the P300 and N100 waves were compared between groups using linear regression. Results The P300 amplitude was significantly reduced in the ARMS group [8. 6±6. 4 microvolt] compared to controls [12. 7±5. 8 microvolt] (p <0. 01). There were no group differences in P300 latency or in the amplitude and latency of the N100. Of the at-risk subjects that were followed up, seven (21%) developed psychosis. Conclusion Reduction in the amplitude of the P300 is associated with an increased vulnerability to psychosis. Neurophysiological and other biological markers may be of use to predict clinical outcomes in populations at high risk.

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v2026.09.13