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The temporal discrimination threshold (TDT) is the shortest time interval at which an observer can discriminate two sequential stimuli as being asynchronous (typically 30-50 ms). It has been shown to be abnormal (prolonged) in... more
The temporal discrimination threshold (TDT) is the shortest time interval at which an observer can discriminate two sequential stimuli as being asynchronous (typically 30-50 ms). It has been shown to be abnormal (prolonged) in neurological disorders, including cervical dystonia, a phenotype of adult onset idiopathic isolated focal dystonia. The TDT is a quantitative measure of the ability to perceive rapid changes in the environment and is considered indicative of the behavior of the visual neurons in the superior colliculus, a key node in covert attentional orienting. This article sets out methods for measuring the TDT (including two hardware options and two modes of stimuli presentation). We also explore two approaches of data analysis and TDT calculation. The application of the assessment of temporal discrimination to the understanding of the pathogenesis of cervical dystonia and adult onset idiopathic isolated focal dystonia is also discussed.
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Research Interests: Engineering, Mathematics, Decision Making, Physical Medicine and Rehabilitation, Gait, and 13 moreEvoked Potentials, Humans, Female, Male, Clinical Neurophysiology, Motor Evoked Potentials, Aged, Middle Aged, Parkinson´s Disease, Parkinson Disease, Case Control Studies, Psychology and Cognitive Sciences, and Medical and Health Sciences
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Research Interests: Acoustics, Research Design, Quality of life, Medication Adherence, Treatment Outcome, and 13 moreMedicine, Ireland, Prospective studies, Humans, Clinical Sciences, Time Factors, Randomized Controlled Trial, Trials, Disease Progression, Equipment Design, Glucocorticoids, Cardiovascular medicine and haematology, and Bronchodilator agents
Visuospatial memory describes our ability to temporarily store and manipulate visual and spatial information and is employed for a wide variety of complex cognitive tasks. Here a visuospatial learning task requiring fine motor control is... more
Visuospatial memory describes our ability to temporarily store and manipulate visual and spatial information and is employed for a wide variety of complex cognitive tasks. Here a visuospatial learning task requiring fine motor control is employed to investigate visuospatial learning in a group of typically developing adults. Electrophysiological and behavioural data is collected during a target location task under two experimental conditions, Target Learning and Target Cued. Movement times are employed as a behavioural metric of performance while dynamic P3b amplitudes and power in the alpha band (approximately 10 Hz) are explored as electrophysiological metrics during visuospatial learning. Results demonstrate that task performance, as measured by movement time, is highly correlated with P3b amplitude and alpha power at a consecutive trial level (trials 1 - 30). The current set of results, in conjunction with the existing literature, suggests that changes in P3b amplitude and alpha...
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Research Interests: Engineering, Communication, Behavioral Sciences, Research Design, Electronics, and 15 moreMedication Adherence, Asthma, Computer Mediated Communication, Electronics and communication, Respiratory Health, Prospective studies, Humans, Medical devices, Asthma Management, Respiratory Diseases, Feedback, Adherence, BMJ, Biomedical Engineering and Bioengineering, and Combination Therapy
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Sensory and perceptual disturbances progress with disease duration in Parkinson's disease (PD) and probably contribute to motor deficits such as bradykinesia and gait disturbances, including freezing of gait (FOG). Simple reaction... more
Sensory and perceptual disturbances progress with disease duration in Parkinson's disease (PD) and probably contribute to motor deficits such as bradykinesia and gait disturbances, including freezing of gait (FOG). Simple reaction time tests are ideal to explore sensory processing, as they require little cognitive processing. Multisensory integration is the ability of the brain to integrate sensory information from multiple modalities into a single coherent percept, which is crucial for complex motor tasks such as gait. The aims of this study were to: 1. Assess differences in unisensory (auditory and visual) and multisensory processing speed in people with PD and age-matched healthy controls. 2. Compare relative differences in unisensory processing in people with PD with disease duration and freezing of gait status taking into account the motor delays, which are invariably present in PD. 3. Compare relative differences in multisensory (audiovisual) processing between the PD coho...
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Noise input signals are commonly used in both linear and non-linear system identification of physiological systems. This method can be applied to electrophysiological analysis of the human auditory system by controlling the modulation of... more
Noise input signals are commonly used in both linear and non-linear system identification of physiological systems. This method can be applied to electrophysiological analysis of the human auditory system by controlling the modulation of the amplitude of a sound stimulus using a precomputed noise signal. In this study we describe how one can obtain an estimate of the linear response of the auditory system using noise signals and we compare it to a standard auditory evoked potential (AEP). Two different noise modulated sounds are tested, broadband noise (BBN) and a 2kHz tone. Results show that the BBN is better at eliciting notable responses. Results also show that although the SNR of the proposed response to the modulated BBN is generally lower than the standard AEP the two responses do correlate well suggesting that the spread spectrum stimulus is a valid method for elicitation of an AEP.
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Asthma is chronic airways disease characterized by recurrent attacks of breathlessness and wheezing. Adherence to medication regimes is a common failing for asthmatic patients and there exists a requirement to monitor such... more
Asthma is chronic airways disease characterized by recurrent attacks of breathlessness and wheezing. Adherence to medication regimes is a common failing for asthmatic patients and there exists a requirement to monitor such patients' adherence. The detection of inhalations from recordings of inhaler use can provide empirical evidence about patients' adherence to their asthma medication regime. Manually listening to recordings of inhaler use is a tedious and time consuming process and thus an algorithm which can automatically and accurately carry out this task would be of great value. This study employs a recording device attached to a commonly used dry powder inhaler to record the acoustic signals of patients taking their prescribed medication. An algorithm was developed to automatically detect and accurately demarcate inhalations from the acoustic signals. This algorithm was tested on a dataset of 255 separate recordings of inhaler use in real world environments. The dataset was obtained from 12 asthma outpatients who attended a respiratory clinic over a three month period. Evaluation of the algorithm on this dataset achieved sensitivity of 95%, specificity of 94% and an accuracy of 89% in detecting inhalations compared to manual inhalation detection.
Research Interests: Computer Science, Asthma, Medicine, Humans, Female, and 8 moreMale, Young Adult, Patient Compliance, Dry Powder Inhalers, Aged, Middle Aged, Adult, and Inhaler
Research Interests: Multiple sclerosis, Audiology, EEG, Electroencephalography, Cognitive Neuroscience, and 15 moreMedicine, Information Processing, Humans, Female, Male, Mental processes, Event Related Potentials, Clinical Sciences, Middle Aged, Adult, Indexation, Cognition disorders, Acoustic Stimulation, Attention deficit disorder with hyperactivity, and High density
In natural environments complex and continuous auditory stimulation is virtually ubiquitous. The human auditory system has evolved to efficiently process an infinitude of everyday sounds, which range from short, simple bursts of noise to... more
In natural environments complex and continuous auditory stimulation is virtually ubiquitous. The human auditory system has evolved to efficiently process an infinitude of everyday sounds, which range from short, simple bursts of noise to signals with a much higher order of information such as speech. Investigation of temporal processing in this system using the event-related potential (ERP) technique has led to great advances in our knowledge. However, this method is restricted by the need to present simple, discrete, repeated stimuli to obtain a useful response. Alternatively the continuous auditory steady-state response is used, although this method reduces the evoked response to its fundamental frequency component at the expense of useful information on the timing of response transmission through the auditory system. In this report, we describe a method for eliciting a novel ERP, which circumvents these limitations, known as the AESPA (auditory-evoked spread spectrum analysis). T...
Research Interests: Computer Science, Auditory Perception, Electroencephalography, Neurophysiology, Medicine, and 14 moreBrain Mapping, Fourier Analysis, Humans, Female, Male, Reaction Time, Young Adult, Adult, Auditory Threshold, Auditory evoked Potentials, Acoustic Stimulation, Statistics as Topic, Psychology and Cognitive Sciences, and Medical and Health Sciences
Research Interests: Genetics, Magnetic Resonance Imaging, Medicine, Brain Mapping, Humans, and 15 moreCaudate Nucleus, Discrimination Learning, Cerebral Cortex, Female, Male, Dystonia, Clinical Sciences, High Resolution, Family Health, Atrophy, Adult, Genetic Susceptibility, Magnetic resonance image, Disability Evaluation, and Corpus striatum
Research Interests: Cognitive Science, Auditory Perception, Psychoacoustics, Attention, Electroencephalography, and 14 moreSpace perception, Brain Mapping, Humans, Cerebral Cortex, Female, Male, Reaction Time, Young Adult, Adult, Analysis of Variance, Auditory evoked Potentials, Auditory Cortex, Neurosciences, and Acoustic Stimulation
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Cognitive assessments are valuable tools in assessing neurological conditions. They are critical in measuring deficits in cognitive function in an array of neurological disorders and during the ageing process. Automation of cognitive... more
Cognitive assessments are valuable tools in assessing neurological conditions. They are critical in measuring deficits in cognitive function in an array of neurological disorders and during the ageing process. Automation of cognitive assessments is one way to address the increasing burden on medical resources for an ever increasing ageing population. This study investigated the suitability of using automated Interactive Voice Response (IVR) technology to deliver a suite of cognitive assessments to older adults using speech as the input modality. Several clinically valid and gold-standard cognitive assessments were selected for implementation in the IVR application. The IVR application was designed using human centred design principles to ensure the experience was as user friendly as possible. Sixty one participants completed two IVR assessments and one face to face (FF) assessment with a neuropsychologist. Completion rates for individual tests were inspected to identify those tests ...
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Freezing of gait (FOG), an episodic gait disturbance characterized by the inability to generate effective stepping, occurs in more than half of Parkinson's disease patients. It is associated with both executive dysfunction and... more
Freezing of gait (FOG), an episodic gait disturbance characterized by the inability to generate effective stepping, occurs in more than half of Parkinson's disease patients. It is associated with both executive dysfunction and attention and becomes most evident during dual-tasking (performing two tasks simultaneously). This study examined the effect of dual motor-cognitive virtual reality training on dual-task performance in FOG. 20 community dwelling participants with Parkinson's disease (13 with FOG, 7 without FOG) participated in a pre-assessment, eight twenty-minute intervention sessions and a post-assessment. The intervention consisted of a virtual reality maze (DFKI, Germany) through which participants navigated by stepping-in-place on a balance board (Nintendo, Japan) under time pressure. This was combined with a cognitive task (Stroop test), which repeatedly divided participants' attention. The primary outcome measures were pre- and post-intervention differences ...
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This paper presents an application of an effective EEG- based Brain Computer Interface design as the control mechanism for an immersive 3-D game. The BCI uses the steady-state visual evoked potential (SSVEP) generated in response to... more
This paper presents an application of an effective EEG- based Brain Computer Interface design as the control mechanism for an immersive 3-D game. The BCI uses the steady-state visual evoked potential (SSVEP) generated in response to phase-reversing checkerboard patterns. Real-time game control and signal processing is facilitated by a combined graphics/DSP/network communications framework. Three methods of feature extraction are compared in a series of offline classification tests. It is found that autoregressive modelling of the EEG trials performs better than more intuitive power spectrum estimation, giving best accuracy of 89%. Two power spectrum estimation methods are also compared during real-time game play. Despite the relatively uncontrolled environment in which the game was played, the performance of the BCI control was robust and relatively consistent across all subjects with 41 of 48 games successfully completed. Performance while playing the game is found to be an improve...
A system of remotely detecting vocal fold pathologies using telephone quality speech recorded during a telephone dialogue is presented. This study aims at developing a dialogue system using VoiceXML for remote diagnosis of voice... more
A system of remotely detecting vocal fold pathologies using telephone quality speech recorded during a telephone dialogue is presented. This study aims at developing a dialogue system using VoiceXML for remote diagnosis of voice pathology. To assess the accuracy of the system, a database of 631 clean speech files of the sustained phonation of the vowel sound /a/ (58 normal subjects, 573 pathologic) from the Disordered Voice Database Model 4337 was transmitted over telephone channels to produce a test corpus. Pitch perturbation features, amplitude perturbation features and a set of measures of the harmonic-to-noise ratio are extracted from the clean and transmitted speech files. These feature sets are used to test and train automatic classifiers, employing the method of Linear Discriminant Analysis. Cross-fold validation was employed to measure classifier performances. While a sustained phonation can be classified as normal or pathologic with accuracy greater than 90%, results indica...
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Orthostatic hypotension (OH) is a frequent cause of orthostatic intolerance (OI) and related symptoms associa/-ted with the occurrence of syncope. The purpose of this study was to examine if older people haemodynamic profile with symptoms... more
Orthostatic hypotension (OH) is a frequent cause of orthostatic intolerance (OI) and related symptoms associa/-ted with the occurrence of syncope. The purpose of this study was to examine if older people haemodynamic profile with symptoms of OI is different to controls during active stand. The database includes sample of 45 participants, aged at least 60 years, where 46.7% (n=21) had symptomatic OI and 53.3% (n=24) did not. Haemodynamic parameters were registered during three phases: a pre-exercise, walking phase and a post-exercise stand. Different haemodynamic parameters such as, pulse rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and cardiac output (CO) were extracted at each of the phases. Results showed differences along phases in both groups. Mean HR differences in phase 1–2 and phase 2–3 showed a statistical signification between symptomatic OI and non-symptomatic OI group. In addition, the combination of the variables rise/fall time-maximum/minimum...
Etiological commonalities are apparent between bipolar disorder and schizophrenia. For example, it is becoming clear that both populations show similar electrophysiological deficits in the auditory domain. Recent studies have also shown... more
Etiological commonalities are apparent between bipolar disorder and schizophrenia. For example, it is becoming clear that both populations show similar electrophysiological deficits in the auditory domain. Recent studies have also shown robust visual sensory processing deficits in patients with schizophrenia using the event-related potential technique, but this has not been formally tested in those with bipolar disorder. Our goal here was to assess whether early visual sensory processing in patients with bipolar disorder, as indexed by decreased amplitude of the P1 component of the visual evoked potential (VEP), would show a similar deficit to that seen in those with schizophrenia. Since the P1 deficit has already been established as an endophenotype in schizophrenia, a finding of commonality between disorders would raise the possibility that it represents a measure of common genetic liability. We visually presented isolated-check stimuli to euthymic patients with a diagnosis of bip...