ORCID Profile
0000-0002-9254-6750
Current Organisations
University of Queensland
,
INSERM U1109
,
University of New South Wales
,
University of Tasmania
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Related Links
Publications
The effect of developmental vitamin D deficiency in male and female Sprague–Dawley rats on decision-making using a rodent gambling task
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.PHYSBEH.2014.09.007
Abstract: Developmental vitamin D (DVD) deficiency is a plausible risk factor for schizophrenia that has been associated with behavioural alterations including disruptions in latent inhibition and response inhibition. The rodent gambling task (rGT) assesses risk-based decision-making, which is a key cognitive deficit observed in schizophrenia patients. The primary aim of this study was to examine risk-based decision-making in DVD-deficient and control rats on the rGT. We also evaluated the performance of female Sprague-Dawley rats on the rGT for the first time. Adult male and female Sprague-Dawley rats from control and vitamin D deficient dams were trained to perform the rGT in standard operant chambers and their performance and choice-preferences were assessed. Female rats were significantly faster to reach rGT training criteria compared with male rats and DVD-deficient rats were faster to reach training criteria than control animals. After reaching stable performance on the rGT DVD-deficient and control rats showed a significant preference for the optimal choice-option in the rGT, but there were no significant effects of sex or diet on these responses. DVD deficiency did not alter the decision-making processes on the rGT because no significant changes in choice-preferences were evident. This is the first study to demonstrate that once established, the performance of females is comparable to male Sprague-Dawley rats on the rGT.
The dorsomedial striatum: an optimal cellular environment for encoding and updating goal-directed learning
Publisher: Elsevier BV
Date: 10-2021
Baseline-dependent effects of amphetamine on attention are associated with striatal dopamine metabolism
Publisher: Springer Science and Business Media LLC
Date: 22-03-2017
DOI: 10.1038/S41598-017-00437-9
Abstract: Psychostimulants, such as hetamine, are widely used to treat attentional deficits. In humans, response to dopaminergic medications is complex with improvement often dependent on baseline performance. Our goal was to determine if attention in rats could be improved by low dose hetamine in a baseline-dependent manner by examining the relationship between task performance, drug response and monoamine levels in corticostriatal tissue. Firstly, rats performed a signal detection task with varying signal durations before administration of saline, 0.1 or 0.25 mg/kg hetamine. Following 0.1 mg/kg hetamine, accuracy in poor performing in iduals increased to that of high performing rats. Furthermore, baseline accuracy correlated with the magnitude of improvement after hetamine. Secondly, neurochemical analysis of monoamine content and gene expression levels in the prefrontal cortex (PFC) and dorsal striatum (CPU) was conducted. CPU homovanillic acid and 5-hydroxyindoleacetic acid levels were increased in poor performers with a significant correlation between the expression of the dopamine transporter gene and baseline accuracy. No changes were found in the PFC. These results indicated poor performance was associated with greater response to hetamine and altered DA and 5-HT neurotransmitter systems in CPU. These results suggest striatal monoamine function may be fundamental to explaining in idual differences in psychostimulant response.
Ral GTPases promote breast cancer metastasis by controlling biogenesis and organ targeting of exosomes.
Publisher: eLife Sciences Publications, Ltd
Date: 06-01-2021
DOI: 10.7554/ELIFE.61539
Abstract: Cancer extracellular vesicles (EVs) shuttle at distance and fertilize pre-metastatic niches facilitating subsequent seeding by tumor cells. However, the link between EV secretion mechanisms and their capacity to form pre-metastatic niches remains obscure. Using mouse models, we show that GTPases of the Ral family control, through the phospholipase D1, multi-vesicular bodies homeostasis and tune the biogenesis and secretion of pro-metastatic EVs. Importantly, EVs from RalA or RalB depleted cells have limited organotropic capacities in vivo and are less efficient in promoting metastasis. RalA and RalB reduce the EV levels of the adhesion molecule MCAM/CD146, which favors EV-mediated metastasis by allowing EVs targeting to the lungs. Finally, RalA, RalB, and MCAM/CD146, are factors of poor prognosis in breast cancer patients. Altogether, our study identifies RalGTPases as central molecules linking the mechanisms of EVs secretion and cargo loading to their capacity to disseminate and induce pre-metastatic niches in a CD146-dependent manner.
Measuring Attention in Rodents: Comparison of a Modified Signal Detection Task and the 5-Choice Serial Reaction Time Task
Publisher: Frontiers Media SA
Date: 14-01-2016
From learning to action: the integration of dorsal striatal input and output pathways in instrumental conditioning
Publisher: Wiley
Date: 31-07-2019
DOI: 10.1111/EJN.13964
Abstract: Considerable evidence suggests that the learning and performance of instrumental actions depend on activity in basal ganglia circuitry however, these two functions have generally been considered independently. Whereas research investigating the associative mechanisms underlying instrumental conditioning has identified critical cortical and limbic input pathways to the dorsal striatum, the performance of instrumental actions has largely been attributed to activity in the dorsal striatal output pathways, with direct and indirect pathway projection neurons mediating action initiation, perseveration and cessation. Here, we discuss evidence that the dorsal striatal input and basal ganglia output pathways mediate the learning and performance of instrumental actions, respectively, with the dorsal striatum functioning as a transition point. From this perspective, the issue of how multiple striatal inputs are integrated at the level of the dorsal striatum and converted into relatively restricted outputs becomes one of critical significance for understanding how learning is translated into action. So too does the question of how learning signals are modulated by recent experience. We propose that this occurs through recurrent corticostriatothalamic feedback circuits that serve to integrate performance signals by updating ongoing action-related learning.
Striatal direct and indirect pathway neurons differentially control the encoding and updating of goal-directed learning
Publisher: eLife Sciences Publications, Ltd
Date: 20-11-2020
DOI: 10.7554/ELIFE.58544
Abstract: The posterior dorsomedial striatum (pDMS) is necessary for goal-directed action however, the role of the direct (dSPN) and indirect (iSPN) spiny projection neurons in the pDMS in such actions remains unclear. In this series of experiments, we examined the role of pDMS SPNs in goal-directed action in rats and found that whereas dSPNs were critical for goal-directed learning and for energizing the learned response, iSPNs were involved in updating that learning to support response flexibility. Instrumental training elevated expression of the plasticity marker Zif268 in dSPNs only, and chemogenetic suppression of dSPN activity during training prevented goal-directed learning. Unilateral optogenetic inhibition of dSPNs induced an ipsilateral response bias in goal-directed action performance. In contrast, although initial goal-directed learning was unaffected by iSPN manipulations, optogenetic inhibition of iSPNs, but not dSPNs, impaired the updating of this learning and attenuated response flexibility after changes in the action-outcome contingency.
Related Organisations
Related Funding Activities
No related grants have been discovered for James Peak.