New Zealand Brain Research Institute

Napier, New Zealand

New Zealand Brain Research Institute

Napier, New Zealand

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Woodward L.J.,University of Canterbury | Woodward L.J.,New Zealand Brain Research Institute | Clark C.A.C.,University of Oregon | Bora S.,University of Canterbury | Inder T.E.,University of Washington
PLoS ONE | Year: 2012

Background: Cerebral white matter abnormalities on term MRI are a strong predictor of motor disability in children born very preterm. However, their contribution to cognitive impairment is less certain. Objective: Examine relationships between the presence and severity of cerebral white matter abnormalities on neonatal MRI and a range of neurocognitive outcomes assessed at ages 4 and 6 years. Design/Methods: The study sample consisted of a regionally representative cohort of 104 very preterm (≤32 weeks gestation) infants born from 1998-2000 and a comparison group of 107 full-term infants. At term equivalent, all preterm infants underwent a structural MRI scan that was analyzed qualitatively for the presence and severity of cerebral white matter abnormalities, including cysts, signal abnormalities, loss of white matter volume, ventriculomegaly, and corpus callosal thinning/myelination. At corrected ages 4 and 6 years, all children underwent a comprehensive neurodevelopmental assessment that included measures of general intellectual ability, language development, and executive functioning. Results: At 4 and 6 years, very preterm children without cerebral white matter abnormalities showed no apparent neurocognitive impairments relative to their full-term peers on any of the domain specific measures of intelligence, language, and executive functioning. In contrast, children born very preterm with mild and moderate-to-severe white matter abnormalities were characterized by performance impairments across all measures and time points, with more severe cerebral abnormalities being associated with increased risks of cognitive impairment. These associations persisted after adjustment for gender, neonatal medical risk factors, and family social risk. Conclusions: Findings highlight the importance of cerebral white matter connectivity for later intact cognitive functioning amongst children born very preterm. Preterm born children without cerebral white matter abnormalities on their term MRI appear to be spared many of the cognitive impairments commonly associated with preterm birth. Further follow-up will be important to assess whether this finding persists into the school years. © 2012 Woodward et al.

Jonmohamadi Y.,University of Otago | Jonmohamadi Y.,New Zealand Brain Research Institute | Poudel G.,New Zealand Brain Research Institute | Poudel G.,Monash University | And 7 more authors.
NeuroImage | Year: 2014

We propose source-space independent component analysis (ICA) for separation, tomography, and time-course reconstruction of EEG and MEG source signals. Source-space ICA is based on the application of singular value decomposition and ICA on the neuroelectrical signals from all brain voxels obtained post minimum-variance beamforming of sensor-space EEG or MEG. We describe the theoretical background and equations, then evaluate the performance of this technique in several different situations, including weak sources, bilateral correlated sources, multiple sources, and cluster sources. In this approach, tomographic maps of sources are obtained by back-projection of the ICA mixing coefficients into the source-space (3-D brain template). The advantages of source-space ICA over the popular alternative approaches of sensor-space ICA together with dipole fitting and power mapping via minimum-variance beamforming are demonstrated. Simulated EEG data were produced by forward head modeling to project the simulated sources onto scalp sensors, then superimposed on real EEG background. To illustrate the application of source-space ICA to real EEG source reconstruction, we show the localization and time-course reconstruction of visual evoked potentials. Source-space ICA is superior to the minimum-variance beamforming in the reconstruction of multiple weak and strong sources, as ICA allows weak sources to be identified and reconstructed in the presence of stronger sources. Source-space ICA is also superior to sensor-space ICA on accuracy of localization of sources, as source-space ICA applies ICA to the time-courses of voxels reconstructed from minimum-variance beamforming on a 3D scanning grid and these time-courses are optimally unmixed via the beamformer. Each component identified by source-space ICA has its own tomographic map which shows the extent to which each voxel has contributed to that component. © 2014 Elsevier Inc.

Poudel G.R.,New Zealand Brain Research Institute | Poudel G.R.,Christchurch Hospital | Innes C.R.H.,New Zealand Brain Research Institute | Innes C.R.H.,Christchurch Hospital | And 3 more authors.
Sleep | Year: 2012

Objectives: To investigate changes in resting cerebral blood flow (CBF) after acute sleep restriction. To investigate the extent to which changes in CBF after sleep restriction are related to drowsiness as manifested in eye-video. Design: Participants were scanned for 5 min using arterial spin labeling (ASL) perfusion imaging after both sleep-restricted and rested nights. Participants were rated for visual signs of drowsiness in the eye-video recorded during the scan. Setting: Lying supine in a 3-Tesla magnetic resonance imaging scanner. Participants: Twenty healthy adults (age 20-37 yr) with no history of neurologic, psychiatric, or sleep disorder, and with usual time in bed of 7.0-8.5 h. Interventions: In the night before the sleep-restricted session, participants were restricted to 4 h time in bed. Results: There was an overall reduction in CBF in the right-lateralized fronto-parietal attentional network after acute sleep restriction, although this was largely driven by participants who showed strong signs of drowsiness in the eye-video after sleep restriction. Change in CBF correlated with change in drowsiness in the basal forebrain-cingulate regions. In particular, there was a pronounced increase in CBF in the basal forebrain and anterior and posterior cingulate cortex of participants who remained alert after sleep restriction. Conclusions: The pattern of cerebral activity after acute sleep restriction is highly dependent on level of drowsiness. Nondrowsy individuals are able to increase activity in the arousal-promoting brain regions and maintain activity in attentional regions. In contrast, drowsy individuals are unable to maintain arousal and show decreased activity in both arousal-promoting and attentional regions.

Moreau P.-H.,French National Center for Scientific Research | Tsenkina Y.,French National Center for Scientific Research | Lecourtier L.,French National Center for Scientific Research | Lopez J.,French National Center for Scientific Research | And 7 more authors.
Brain Structure and Function | Year: 2013

Medial thalamic damage produces memory deficits in humans (e.g., Korsakoff's syndrome) and experimental animals. Both the anterior thalamic nuclei (ATN) and rostral intralaminar plus adjacent lateral thalamic nuclei (ILN/LT) have been implicated. Based on the differences in their main connections with other neural structures, we tested the prediction that ATN lesions would selectively impair acquisition of spatial location discrimination, reflecting a hippocampal system deficit, whereas ILN/LT lesions would impair acquisition of visual pattern discrimination, reflecting a striatal system deficit. Half the rats were first trained in a spatial task in a water maze before switching to a visual task in the same maze, while the remainder were tested with the reverse order of tasks. Compared with sham-operated controls, (1) rats with ATN lesions showed impaired place learning, but normal visual discrimination learning, (2) rats with ILN/LT lesions showed no deficit on either task. Rats with ATN lesions were also hyperactive when their home cage was placed in a novel room and remained more active than ILN/LT or SHAM rats for the subsequent 21 h, especially during the nocturnal phase. These findings confirmed the influence of ATN lesions on spatial learning, but failed to support the view that ILN/LT lesions disrupt striatal-dependent memory. © 2012 Springer-Verlag.

Borrie S.A.,University of Canterbury | McAuliffe M.J.,University of Canterbury | Liss J.M.,Arizona State University | O'Beirne G.A.,University of Canterbury | Anderson T.J.,New Zealand Brain Research Institute
Journal of the Acoustical Society of America | Year: 2013

This investigation examined perceptual learning of dysarthric speech. Forty listeners were randomly assigned to one of two identification training tasks, aimed at highlighting either the linguistic (word identification task) or indexical (speaker identification task) properties of the neurologically degraded signal. Twenty additional listeners served as a control group, passively exposed to the training stimuli. Immediately following exposure to dysarthric speech, all three listener groups completed an identical phrase transcription task. Analysis of listener transcripts revealed remarkably similar intelligibility improvements for listeners trained to attend to either the linguistic or the indexical properties of the signal. Perceptual learning effects were also evaluated with regards to underlying error patterns indicative of segmental and suprasegmental processing. The findings of this study suggest that elements within both the linguistic and indexical properties of the dysarthric signal are learnable and interact to promote improved processing of this type and severity of speech degradation. Thus, the current study extends support for the development of a model of perceptual processing in which the learning of indexical properties is encoded and retained in conjunction with linguistic properties of the signal. © 2013 Acoustical Society of America.

Alamri Y.A.S.,New Zealand Brain Research Institute
Journal of Medical Ethics | Year: 2016

It is human nature, perhaps more so for doctors and nurses, to comfort children in distress. Unfortunately, however, necessary medical procedures carried out by healthcare providers (eg, venipuncture) can often result in pain and discomfort, which may in turn cause the provider a degree of guilt and distress. Is it ever acceptable to comfort a paediatric patient with a kiss? This essay examines the literature published on this subject reflecting on a recent encounter with a patient. © 2016 by the BMJ Publishing Group Ltd & Institute of Medical Ethics.

Harland B.C.,University of Canterbury | Collings D.A.,University of Canterbury | Mcnaughton N.,University of Otago | Abraham W.C.,University of Otago | And 3 more authors.
Hippocampus | Year: 2014

Injury to the anterior thalamic nuclei (ATN) may affect both hippocampus and retrosplenial cortex thus explaining some parallels between diencephalic and medial temporal lobe amnesias. We found that standard-housed rats with ATN lesions, compared with standard-housed controls, showed reduced spine density in hippocampal CA1 neurons (basal dendrites, -11.2%; apical dendrites, -9.6%) and in retrospenial granular b cortex (Rgb) neurons (apical dendrites, -20.1%) together with spatial memory deficits on cross maze and radial-arm maze tasks. Additional rats with ATN lesions were also shown to display a severe deficit on spatial working memory in the cross-maze, but subsequent enriched housing ameliorated their performance on both this task and the radial-arm maze. These enriched rats with ATN lesions also showed recovery of both basal and apical CA1 spine density to levels comparable to that of the standard-housed controls, but no recovery of Rgb spine density. Inspection of spine types in the CA1 neurons showed that ATN lesions reduced the density of thin spines and mushroom spines, but not stubby spines; while enrichment promoted recovery of thin spines. Comparison with enriched rats that received pseudo-training, which provided comparable task-related experience, but no explicit spatial memory training, suggested that basal CA1 spine density in particular was associated with spatial learning and memory performance. Distal pathology in terms of reduced integrity of hippocampal and retrosplenial microstructure provides clear support for the influence of the ATN lesions on the extended hippocampal system. The reversal by postoperative enrichment of this deficit in the hippocampus but not the retrosplenial cortex may indicate region-specific mechanisms of recovery after ATN injury. © 2014 Wiley Periodicals, Inc.

Anderson T.J.,University of Otago | MacAskill M.R.,New Zealand Brain Research Institute
Nature Reviews Neurology | Year: 2013

The neural pathways and brain regions involved in eye movements during ocular fixation and gaze control include the cerebrum, brainstem and cerebellum, and abnormal eye movements can indicate the presence of neurodegeneration. In some patients, oculomotor signs are key to making a diagnosis. Careful clinical examination of eye movements in patients with neurodegenerative disorders is, therefore, an invaluable adjunct to neurological and cognitive assessments. Eye movement recordings in the laboratory are generally not necessary for diagnostic purposes, but can be a useful addition to the clinical examination. Laboratory recordings of eye movements can provide valuable information about disease severity, progression or regression in neurodegenerative disease, and hold particular promise for objective evaluation of the efficacy of putative neuroprotective and neurorestorative therapies. For example, aspects of saccade performance can be tested to probe both motor and cognitive aspects of oculomotor behaviour. This Review describes the oculomotor features of the major age-related movement disorders, including Parkinson disease, Huntington disease, dementia and other neurodegenerative disorders. Findings in presymptomatic individuals and changes associated with disease progression are discussed. © 2013 Macmillan Publishers Limited. All rights reserved.

Miles A.,University of Canterbury | Miles A.,University of Auckland | Huckabee M.-L.,University of Canterbury | Huckabee M.-L.,New Zealand Brain Research Institute
International Journal of Speech-Language Pathology | Year: 2013

This study investigated the inter-rater and intra-rater reliability of subjective judgements of cough in patients following inhalation of citric acid. Eleven speech-language pathologists (SLPs) currently using cough reflex testing in their clinical practice (experienced raters) and 34 SLPs with no experience using cough reflex testing (inexperienced raters) were recruited to the study. Participants provided a rating of strong, weak, or absent to 10 video segments of cough responses elicited by inhalation of nebulized citric acid. The same video segments presented in a different sequence were re-evaluated by the same clinicians following a 15-minute break. Inter-rater reliability for experienced raters was calculated with a Fleiss' generalized kappa of .487; intra-rater reliability was higher with a kappa of .700. Inexperienced raters showed similar reliability, with kappa values for inter-rater and intra-rater reliability of .363 and .618, respectively. In conclusion, SLPs demonstrate only fair-to-moderate reliability in subjectively judging a patient's cough response to citric acid. Experience in making cough judgements does not improve inter-rater reliability significantly. Further validity and reliability research, including an evaluation of the effect of training on judgement reliability, would be beneficial for guiding clinical policies. © 2013 The Speech Pathology Association of Australia Limited.

Borrie S.A.,University of Canterbury | McAuliffe M.J.,University of Canterbury | Liss J.M.,Arizona State University | O'Beirne G.A.,University of Canterbury | Anderson T.J.,New Zealand Brain Research Institute
Journal of the Acoustical Society of America | Year: 2012

Differences in perceptual strategies for lexical segmentation of moderate hypokinetic dysarthric speech, apparently related to the conditions of the familiarization procedure, have been previously reported [Borrie, Language and Cognitive Processes (2012)]. The current follow-up investigation examined whether this difference was also observed when familiarization stimuli highlighted syllabic strength contrast cues. Forty listeners completed an identical transcription task following familiarization with dysarthric phrases presented under either passive or explicit learning conditions. Lexical boundary error patterns revealed that syllabic strength cues were exploited in both familiarization conditions. Comparisons with data previously reported afford further insight into perceptual learning of dysarthric speech. © 2012 Acoustical Society of America.

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