Van der Veer Institute for Parkinsons and Brain Research

Christchurch, New Zealand

Van der Veer Institute for Parkinsons and Brain Research

Christchurch, New Zealand
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Davie-Gray A.,University of Canterbury | Moor S.,University of Otago | Spencer C.,University of Canterbury | Woodward L.J.,University of Canterbury | And 2 more authors.
Neurotoxicology and Teratology | Year: 2013

Pregnant women with substance dependency are a high-risk psychiatric and obstetric population, with their infants also at elevated neonatal risk. This paper draws on prospective, longitudinal data from a regional cohort of 81 methadone-maintained (MM) and 107 comparison women and their infants to describe the obstetric, socio-familial and mental health needs of women in methadone maintenance treatment during pregnancy. Of particular interest was the extent and pattern of maternal licit and illicit drug use over the course of pregnancy. Results showed that MM women had complex reproductive histories, chronic health problems, and were subject to high rates of socioeconomic adversity and comorbid mental health problems. During pregnancy, more than half continued to use licit and illicit drugs, although there was a general trend for drug use to reduce over time. No differences were observed between women maintained on low (12.5-61.0. mg/day) and high (61.1-195.0. mg/day) doses of methadone, with the exception of opiate abuse which was higher in the low dose group (p=.07). Findings highlight that pregnant women enrolled in MMT and their infants represent a vulnerable group with complex, social, obstetric and psychiatric needs. They also reinforce the need for services that can provide on-going wrap-around, multidisciplinary and multiagency care for these high risk dyads, both during pregnancy and in the transition to parenthood. © 2013 Elsevier Inc.

Abdul Wahab N.,Van der Veer Institute for Parkinsons and Brain Research | Abdul Wahab N.,University of Canterbury | Abdul Wahab N.,Universiti Sains Malaysia | Jones R.D.,Van der Veer Institute for Parkinsons and Brain Research | And 4 more authors.
Physiology and Behavior | Year: 2010

This project evaluated the effects of olfactory and gustatory stimuli on the amplitude and latency of motor-evoked potentials (MEPs) from the submental muscles when evoked by transcranial magnetic stimulation (TMS). Sixteen healthy volunteers (8 males; age range 19-43) participated in the study. Lemon concentrate at 100% and diluted in water to 25% were presented separately as odor and tastant stimuli. Tap water was used as control. 15 trials of TMS-evoked MEPs triggered by volitional contraction of the submental muscles and volitional swallowing were measured at baseline, during control condition, during stimulus presentation, and immediately, 30-, 60-, and 90-min poststimulation for each of the four stimulus presentations. Experiments were repeated using the combined odor and tastant concentrations that most influenced the MEP independently. Differences in MEP amplitude measured during swallowing were seen at 30-, 60-, and 90-min poststimulation for simultaneous olfactory and gustatory stimulation as opposed to no differences seen at any point for stimuli presented separately. This study has shown that combined odor and tastant stimulation (i.e., flavor) can increase MEP amplitude during swallowing and that this enhancement of MEP can persist for at least 90. min following stimulation. As increased MEP amplitude has been associated with improved swallowing performance, a follow-up study is underway to determine the biomechanical changes produced by altered MEPs to facilitate translation of these data to clinical dysphagia management. © 2010 Elsevier Inc.

Abdul Wahab N.,Van der Veer Institute for Parkinsons and Brain Research | Abdul Wahab N.,University of Canterbury | Abdul Wahab N.,Universiti Sains Malaysia | Jones R.D.,Van der Veer Institute for Parkinsons and Brain Research | And 4 more authors.
Physiology and Behavior | Year: 2011

We have previously documented increased amplitude of motor-evoked potentials (MEPs) from the submental muscles during volitional swallowing following simultaneous odor and tastant stimulation. The MEP denotes neural excitability from the motor cortex to the target muscle(s). However, it is unknown if changes in the MEP transfer to the swallowing muscles to facilitate improved swallowing. Thus, we sought to evaluate changes in the biomechanics of swallowing following stimulation protocols that are known to influence neural excitability. Sixteen healthy participants were exposed to low and high concentrations of lemon odor and tastant. The odor and tastant concentrations which produced the highest amplitude of submental electromyography (EMG) were then combined for simultaneous stimuli presentation. Outcome measures included EMG from the submental muscles, as well as lingual and pharyngeal manometry. Poststimulation results showed decreased midglossopalatal pressure at 30. min and decreased duration at anterior and midglossopalatal pressure and increased EMG duration at 60. min. This study strengthens the justification for the use of flavor in managing patients with dysphagia as long-term changes were present in the poststimulation period. © 2010 Elsevier Inc.

Van Stockum S.,Van der Veer Institute for Parkinsons and Brain Research | Van Stockum S.,University of Otago | Macaskill M.R.,Van der Veer Institute for Parkinsons and Brain Research | Macaskill M.R.,University of Otago | And 4 more authors.
European Journal of Neuroscience | Year: 2011

Numerous studies have shown that Parkinson's disease (PD) affects the ability to generate voluntary saccades and the ability to suppress reflexive saccades. The effects of PD on the generation of reflexive saccades, however, are not clear. Some studies report impairments, but there are also reports of abnormal facilitation or hyper-reflexivity of the saccade system in PD. Meanwhile, it has been reported that the concurrent performance of a perceptual discrimination task facilitates saccade initiation and reduces saccade latencies in healthy subjects [A. Montagnini and L. Chelazzi (2005)Vis. Res., 45, 3391-3401; L. Trottier and J. Pratt (2005)Vis. Res., 45, 1349-1354]. To investigate the circumstances under which the saccade system may appear hyper-reflexive in PD, we compared reflexive saccades with and without a concurrent perceptual discrimination task in 20 PD patients and 20 controls. Without the discrimination task, the PD group produced reflexive saccades at normal latencies. The discrimination task reduced saccade latencies more in the PD group than in the control group, resulting in abnormally short mean reflexive saccade latencies in the PD group. The discrimination task increased saccade gain in both groups, but saccades in the PD group remained hypometric as compared with saccades in the control group. We conclude that the attentional demands of this paradigm revealed a hypersensitivity to visual inputs in the PD group. © 2011 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Doeltgen S.H.,University of Canterbury | Doeltgen S.H.,Van der Veer Institute for Parkinsons and Brain Research | Dalrymple-Alford J.,University of Canterbury | Dalrymple-Alford J.,Van der Veer Institute for Parkinsons and Brain Research | And 3 more authors.
Neurorehabilitation and Neural Repair | Year: 2010

Background. Neuromuscular electrical stimulation (NMES) of the muscles underlying the pharynx and faucial pillars affects the excitability of corticobulbar projections in a frequency- and duration-specific manner. The anterior hyomandibular (submental) muscles are primary targets for the clinical application of NMES to improve disordered swallowing, but the optimal NMES parameters for this application are unknown. Objective. To determine the influence of NMES parameters on the excitability of corticobulbar projections to the submental musculature. Methods. Transcranial magnetic stimulation (TMS) was used in event-related protocols, triggered by either volitional contraction of the submental muscles or pharyngeal swallowing, to assess corticobulbar excitability prior to, immediately following, and 30, 60, and 90 minutes post-NMES in 25 healthy volunteers. In the first 2 experiments, 4 stimulus frequencies (5, 20, 40, and 80 Hz) and 3 NMES dosages, manipulated through stimulus train durations or number of repetitions, were evaluated. The optimal excitatory NMES triggered by volitional swallowing (event-related NMES) was then replicated in a new sample and contrasted with non-event-related NMES (either discrete events or continuously for 1 hour). Results. It was found that 80Hz NMES increased motor-evoked potential (MEP) amplitude at 30 minutes and 60 minutes poststimulation only after 60 repetitions of 4-s event-related NMES trains. Non-event-related and continuous NMES did not affect MEP amplitudes. No changes in MEP onset latencies were observed. Conclusions. Changes in corticobulbar excitability induced by NMES of the submental muscle group are frequency and dose dependent and only occur after NMES triggered by volitional swallowing. Underlying neural mechanisms are discussed. © 2010 The Author(s).

Melzer T.R.,Van der Veer Institute for Parkinsons and Brain Research | Melzer T.R.,University of Otago | Watts R.,Van der Veer Institute for Parkinsons and Brain Research | Watts R.,University of Canterbury | And 13 more authors.
Journal of Neurology, Neurosurgery and Psychiatry | Year: 2012

Objective: Mild cognitive impairment and dementia are common non-motor features of Parkinson's disease (PD). The aim of this study was to characterise grey matter changes associated with clearly defined stages of cognitive impairment in PD using structural MRI. Methods: 96 PD subjects were classified using detailed cognitive testing as PD with normal cognition (PD-N, n=57), PD with mild cognitive impairment (PD-MCI, n=23) or PD with dementia (PD-D, n=16); 34 controls matched for mean age and sex ratio also participated. Grey matter volume differences were evaluated using voxel based morphometry of grey matter segments derived from T1 weighted 3 T MRI, and multiple linear regression assessed the relationship between cognitive and motor impairments and grey matter concentration. Results: Compared with controls, no grey matter differences were found in PD-N. PD-MCI showed limited grey matter atrophy in the temporal, parietal and frontal cortex as well as the bilateral caudal hippocampus, amygdala and right putamen. PD-D subjects exhibited far more extensive atrophy in regions involved in PD-MCI but also had reduced grey matter volume in other large areas of the temporal lobe (including the parahippocampi), the intracalcarine and lingual gyri, posterior cingulate gyrus, frontal regions and bilateral caudate. Grey matter loss in PD correlated with global cognitive score but not motor impairment in most of these regions. Interpretation: Marked grey matter atrophy occurs in PD with dementia but far less extensive changes are evident in PD-MCI. Some grey matter atrophy precedes the development of dementia but may be accelerated once frank dementia begins.

Pritchard V.E.,University of Canterbury | Pritchard V.E.,Van der Veer Institute for Parkinsons and Brain Research | Woodward L.J.,University of Canterbury | Woodward L.J.,Van der Veer Institute for Parkinsons and Brain Research
Psychological Assessment | Year: 2011

Executive functions (EF) necessary for purposeful goal-directed activities undergo rapid change and development during the preschool years. However, of the few psychometrically valid measures of EF suitable for use with preschoolers, information on task sensitivity and predictive validity is scant. The neurodevelopmental correlates of early executive difficulties are also largely unknown. In this study, the discriminant and predictive validity of the recently developed Shape School task (Espy, Bull, Martin, & Stroup, 2006) was examined with data from a regional sample of 209 preschool children at age 4 years. A 2-tiered measurement approach was used, with task completion examined in addition to efficiency. Children's performance was also examined in relation to functioning in a range of neurodevelopmental domains. The Shape School task showed some usefulness in capturing expected differences between at-risk and typically developing children. Performance loaded heavily on language and global cognitive abilities. However, several other factors were also implicated, including attention, motor skills, and ocular control. In addition, task completion and efficiency scores appeared to reflect different aspects of performance, and their associations with neurodevelopmental function and later academic achievement on the Woodcock-Johnson Tests of Achievement at age 6 years also differed. Implications for the application of the Shape School task are discussed. © 2011 American Psychological Association.

Leow L.P.,Van der Veer Institute for Parkinsons and Brain Research | Huckabee M.-L.,University of Canterbury | Huckabee M.-L.,Van der Veer Institute for Parkinsons and Brain Research | Anderson T.,Van der Veer Institute for Parkinsons and Brain Research | And 2 more authors.
Dysphagia | Year: 2010

This prospective, cross-sectional study evaluated the impact of dysphagia on quality of life in healthy ageing and in subjects with Parkinson's disease (PD) using the Swallowing Quality of Life (SWAL-QOL) questionnaire. Sixteen healthy young adults (8 males, mean age = 25.1 years) and 16 healthy elders (8 males, mean age = 72.8 years) were recruited. Thirty-two subjects with idiopathic PD (mean age = 68.5 years) were recruited from a movement disorders clinic. The severity of PD was staged using the Hoehn and Yahr scale. Results revealed that elders experienced symptoms of dysphagia more frequently than young adults but the overall SWAL-QOL scores were not significantly different. Subjects with PD who experienced dysphagia reported greatly reduced QOL, and significant differences were found in all but one subsection of the SWAL-QOL. Disease progression detrimentally impacts QOL, with subjects in later-stage PD experiencing further reduction in the desire to eat, difficulty with food selection, and prolonged eating duration. These features, which increase with disease severity, are likely to impact negatively upon nutritional status, which is already under threat from PD-related dysphagia. © 2009 Springer Science+Business Media, LLC.

Peiris M.T.,Van der Veer Institute for Parkinsons and Brain Research
Journal of neural engineering | Year: 2011

A system capable of reliably detecting lapses in responsiveness ('lapses') has the potential to increase safety in many occupations. We have developed an approach for detecting the state of lapsing with second-scale temporal resolution using data from 15 subjects performing a one-dimensional (1D) visuomotor tracking task for two 1 h sessions while their electroencephalogram (EEG), facial video, and tracking performances were recorded. Lapses identified using a combination of facial video and tracking behaviour were used to train the classification models. Linear discriminant analysis was used to form detection models based on individual subject data and stacked generalization was utilized to combine the outputs of multiple classifiers to obtain the final prediction. The performance of detectors estimating the lapse/not-lapse state at 1 Hz based on power spectral features, approximate entropy, fractal dimension, and Lempel-Ziv complexity of the EEG was compared. Best lapse state estimation performance was achieved using the detector model created using power spectral features with an area under the curve from receiver operating characteristic analysis of 0.86 ± 0.03 (mean±SE) and an area under the precision-recall curve of 0.43 ± 0.09. A novel technique was developed to provide improved estimation of accuracy of detection of variable-duration events. Via this approach, we were able to show that the detection of lapse events from spectral power features was of moderate accuracy (sensitivity = 73.5%, selectivity = 25.5%).

Farr H.,University of Canterbury | Farr H.,Van der Veer Institute for Parkinsons and Brain Research | David T.,University of Canterbury
Journal of Theoretical Biology | Year: 2011

Functional hyperemia is an important metabolic autoregulation mechanism by which increased neuronal activity is matched by a rapid and regional increase in blood supply. This mechanism is facilitated by a process known as "neurovascular coupling"-the orchestrated communication system involving neurons, astrocytes and arterioles. Important steps in this process are the production of EETs in the astrocyte and the release of potassium, via two potassium channels (BK and KIR), into the perivascular space. We provide a model which successfully accounts for several observations seen in experiment. The model is capable of simulating the approximate 15% arteriolar dilation caused by a 60-s neuronal activation (modelled as a release of potassium and glutamate into the synaptic cleft). This model also successfully emulates the paradoxical experimental finding that vasoconstriction follows vasodilation when the astrocytic calcium concentration (or perivascular potassium concentration) is increased further. We suggest that the interaction of the changing smooth muscle cell membrane potential and the changing potassium-dependent resting potential of the KIR channel are responsible for this effect. Finally, we demonstrate that a well-controlled mechanism of potassium buffering is potentially important for successful neurovascular coupling. © 2011 Elsevier Ltd.

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