Publications by authors named "Ian Kirk"

Purpose: Anxiety disorders are a major global issue. Diagnosis via symptoms, not biological causes, delivers poor treatment outcomes. Our frontal EEG biomarker, Goal Conflict Specific Rhythmicity (GCSR; 4-12 Hz), developed from our long-standing detailed neuropsychological theory of anxiety processes, is reduced by all chemical types of selective anxiolytic and is high in cases across a range of currently diagnosed anxiety disorders.

View Article and Find Full Text PDF

Actions are rarely devoid of emotional content. Thus, a more complete picture of the neural mechanisms underlying the mental simulation of observed actions requires more research using emotion information. The present study used high-density electroencephalography to investigate mental simulation associated with facial emotion categorisation.

View Article and Find Full Text PDF

Autism spectrum disorder is an increasingly prevalent and debilitating neurodevelopmental condition and an electroencephalogram (EEG) diagnostic challenge. Despite large amounts of electrophysiological research over many decades, an EEG biomarker for autism spectrum disorder (ASD) has not been found. We hypothesized that reductions in complex dynamical system behaviour in the human central nervous system as part of the macroscale neuronal function during cognitive processes might be detectable in whole EEG for higher-risk ASD adults.

View Article and Find Full Text PDF

Long-term potentiation (LTP) is a form of neuroplasticity commonly implicated in mechanistic models of learning and memory. Acute exercise can boost LTP in the motor cortex, and is associated with a shift in excitation/inhibition (E:I) balance, but whether this extends to other regions such as the visual cortex is unknown. We investigated the effect of a preceding bout of exercise on LTP induction and the E:I balance in the visual cortex using electroencephalography (EEG).

View Article and Find Full Text PDF

Auditory processing disorder (APD) is a listening impairment that some school-aged children may experience despite having normal peripheral hearing. Recent resting-state functional magnetic resonance imaging (MRI) has revealed an alteration in regional functional brain topology in children with APD. However, little is known about the structural organization in APD.

View Article and Find Full Text PDF
Article Synopsis
  • Children with auditory processing disorder (APD) struggle with hearing in noisy environments even though their hearing tests are normal; there’s ongoing debate about whether these issues stem from sensory processing or cognitive factors.
  • A study using MRI on 57 children (28 with APD and 29 healthy controls) found that while overall brain network properties were similar, children with APD had distinct brain hub architecture in certain functional modules.
  • Specifically, reduced connectivity was noted in auditory-related brain regions, indicating altered brain network organization in APD children, which is linked to their ability to process spatialized auditory information.
View Article and Find Full Text PDF

Aotearoa New Zealand's population is ageing. Increasing life expectancy is accompanied by increases in prevalence of Alzheimer's Disease (AD) and ageing-related disorders. The multicentre Dementia Prevention Research Clinic longitudinal study aims to improve understanding of AD and dementia in Aotearoa, in order to develop interventions that delay or prevent progression to dementia.

View Article and Find Full Text PDF

Purpose: Individualised predictive models of cognitive decline require disease-monitoring markers that are repeatable. For wide-spread adoption, such markers also need to be reproducible at different locations. This study assessed the repeatability and reproducibility of MRI markers derived from a dementia protocol.

View Article and Find Full Text PDF

Neurophysiological research on the bilingual activity of interpretation or interpreting has been very fruitful in understanding the bilingual brain and has gained increasing popularity recently. Issues like word interpreting and the directionality of interpreting have been attended to by many researchers, mainly with localizing techniques. Brain structures such as the dorsolateral prefrontal cortex have been repeatedly identified during interpreting.

View Article and Find Full Text PDF

Tentative results from feasibility analyses are critical for planning future randomized control trials (RCTs) in the emerging field of neural biomarkers of behavioral interventions. The current feasibility study used MRI-derived diffusion imaging data to investigate whether it would be possible to identify neural biomarkers of a behavioral intervention among people diagnosed with autism spectrum disorder (ASD). The corpus callosum has been linked to cognitive processing and callosal abnormalities have been previously found in people diagnosed with ASD.

View Article and Find Full Text PDF

Cerebral blood flow (CBF) measured with arterial spin labelling (ASL) magnetic resonance imaging (MRI) reflects cerebral perfusion, related to metabolism, and arterial transit time (ATT), related to vascular health. Our aim was to investigate the spatial coefficient of variation (sCoV) of CBF maps as a surrogate for ATT, in volunteers meeting criteria for subjective cognitive decline (SCD), amnestic mild cognitive impairment (MCI) and probable Alzheimer's dementia (AD). Whole-brain pseudo continuous ASL MRI was performed at 3 T in 122 participants (controls = 20, SCD = 44, MCI = 45 and AD = 13) across three sites in New Zealand.

View Article and Find Full Text PDF

Background: Longitudinal neuroimaging provides spatiotemporal brain data (STBD) measurement that can be utilised to understand dynamic changes in brain structure and/or function underpinning cognitive activities. Making sense of such highly interactive information is challenging, given that the features manifest intricate temporal, causal relations between the spatially distributed neural sources in the brain.

Methods: The current paper argues for the advancement of deep learning algorithms in brain-inspired spiking neural networks (SNN), capable of modelling structural data across time (longitudinal measurement) and space (anatomical components).

View Article and Find Full Text PDF

Psychiatric diagnoses currently rely on a patient's presenting symptoms or signs, lacking much-needed theory-based biomarkers. Our neuropsychological theory of anxiety, recently supported by human imaging, is founded on a longstanding, reliable, rodent 'theta' brain rhythm model of human clinical anxiolytic drug action. We have now developed a human scalp EEG homolog-goal-conflict-specific rhythmicity (GCSR), i.

View Article and Find Full Text PDF

Long-term potentiation (LTP) is one of the most widely studied forms of neural plasticity, and is thought to be the principle mechanism underlying long-term memory and learning in the brain. Sensory paradigms utilising electroencephalography (EEG) and sensory stimulation to induce LTP have allowed translation from rodent and primate invasive research to non-invasive human investigations. This review focusses on visual sensory LTP induced using repetitive visual stimulation, resulting in changes in the visually evoked response recorded at the scalp with EEG.

View Article and Find Full Text PDF

Animal studies have consistently observed neuronal death following methamphetamine (MA) administration, however, these have not been systematically reviewed. This systematic review aims to present the evidence for MA-induced neuronal death in animals (rodents) and identify the regions affected. Locating the brain regions in which neuronal death occurs in animal studies will provide valuable insight into the linkage between MA consumption and the structural alterations observed in the human brain.

View Article and Find Full Text PDF
Article Synopsis
  • Ketamine shows rapid antidepressant effects by enhancing neural plasticity, specifically through long-term potentiation (LTP) in the brain.
  • A study with 30 depressed patients found that 70% experienced significant symptom reduction after a single dose of ketamine, with measurable changes in brain activity relevant to LTP.
  • The results suggest that ketamine may improve neural connectivity and functioning, supporting the idea that boosting neural plasticity is essential for its antidepressant effects.
View Article and Find Full Text PDF

A single nucleotide polymorphism (SNP) in the gene coding for brain-derived neurotrophic factor (BDNF) has previously been associated with a reduction in recognition memory performance. While previous findings have highlighted that this SNP contributes to recognition memory, little is known about its influence on subprocesses of recognition, familiarity and recollection. Previous research has reported reduced hippocampal volume and decreased fractional anisotropy in carriers of the Met allele across a range of white matter tracts, including those networks that may support recognition memory.

View Article and Find Full Text PDF

: Long-term potentiation (LTP) is recognised as a core neuronal process underlying long-term memory. However, a direct relationship between LTP and human memory performance is yet to be demonstrated. The first aim of the current study was thus to assess the relationship between LTP and human long-term memory performance.

View Article and Find Full Text PDF

The mirror neuron network (MNN) has been proposed as a neural substrate of action understanding. Electroencephalography (EEG) mu suppression has commonly been studied as an index of MNN activity during execution and observation of hand and finger movements. However, in order to establish its role in higher order processes, such as recognizing and sharing emotions, more research using social emotional stimuli is needed.

View Article and Find Full Text PDF
Article Synopsis
  • Spatial navigation involves two main strategies: allocentric (using an external reference) and egocentric (based on one's own position), with the latter further divided into egocentric-cue and egocentric-response.
  • A new virtual tool called the Hex Maze distinguishes between these strategies and measures their use, including preference and competence, across different participants.
  • The study found no significant sex differences in overall navigation ability but supported existing findings on strategy preferences, suggesting that individuals can learn to navigate using multiple strategies effectively.
View Article and Find Full Text PDF

Musical training provides an ideal platform for investigating action representation for sound. Learning to play an instrument requires integration of sensory and motor perception-action processes. Functional neuroimaging studies have indicated that listening to trained music can result in the activity in premotor areas, even after a short period of training.

View Article and Find Full Text PDF

Background: Exercise-induced cognitive improvements have traditionally been observed following aerobic exercise interventions; that is, sustained sessions of moderate intensity. Here, we tested the effect of a 6 week high-intensity training (HIT) regimen on measures of cognitive control and working memory in a multicenter, randomized (1:1 allocation), placebo-controlled trial.

Methods: 318 children aged 7-13 years were randomly assigned to a HIT or an active control group matched for enjoyment and motivation.

View Article and Find Full Text PDF

The catechol-O-methyltransferase (COMT) val158met polymorphism affects the breakdown of synaptic dopamine. Consequently, this polymorphism has been associated with a variety of neurophysiological and behavioral outcomes. Some of the effects have been found to be sex-specific and it appears estrogen may act to down-regulate the activity of the COMT enzyme.

View Article and Find Full Text PDF
Article Synopsis
  • Piperazine-containing party pills, specifically BZP and TFMPP, were popular legal alternatives to illegal drugs in New Zealand until 2008, but their effects on human neural processing were not well understood.
  • A study investigated the impact of these substances on interhemispheric transfer of information (IHTT) using EEG techniques, comparing their effects against a placebo and dexamphetamine in healthy males.
  • Results showed that only TFMPP significantly affected neural latency and IHTT, whereas BZP and the combination with TFMPP did not, and no significant changes were noted in reaction times compared to the placebo.
View Article and Find Full Text PDF