ORCID Profile
0000-0002-0637-0411
Current Organisations
University of Adelaide
,
Cybin Inc
,
PurMinds Neuropharma
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Biological Psychology (Neuropsychology, Psychopharmacology, Physiological Psychology) | Psychology | Central Nervous System
Behaviour and Health | Expanding Knowledge in Psychology and Cognitive Sciences |
Publisher: INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols
Date: 20-08-2021
DOI: 10.37766/INPLASY2021.8.0075
Abstract: Is the perineuronal net structure within emotional processing brain regions associated with changes in affective state? The objective of this scoping review is to bring together the literature on human and animal studies which have measured perineuronal net structure in brain regions associated with emotional processing (such as but not limited to amygdala, hippoc us and prefrontal cortex). Perineuronal nets are a specialised form of condensed extracellular matrix that enwrap and protect neurons (Suttkus et al., 2016), regulate synaptic plasticity (Celio and Blumcke, 1994) and ion homeostasis (Morawski et al., 2015). Perineuronal nets are dynamic structures that are influenced by external and internal environmental shifts – for ex le, increasing in intensity and number in response to stressors (Blanco and Conant, 2021) and pharmacological agents (Riga et al., 2017). This review’s objective is to generate a compilation of existing knowledge regarding the structural changes of perineuronal nets in experimental studies that manipulate affective state, including those that alter environmental stressors. The outcomes will inform future research directions by elucidating non-cellular central nervous system mechanisms that underpin positive and negative emotional states. These methods may also be targets for manipulation to manage conditions of depression or promote wellbeing. Population: human and animal Condition: affective state as determined through validated behavioural assessment methods or established biomarkers. This includes both positive and negative affective states. Context: PNN structure, measuringPNNs.
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.TEM.2019.10.005
Abstract: Globally, obesity has reached epidemic proportions. The rapidly increasing numbers of overweight people can be traced back to overconsumption of energy-dense, poor-quality foods as well as physical inactivity. This development has far-reaching and costly implications. Not only is obesity associated with serious physiological and psychological complications, but mounting evidence also indicates a ripple effect through generations via epigenetic changes. Parental obesity could induce intergenerational and transgenerational changes in metabolic and brain function of the offspring. Most research has focused on maternal epigenetic and gestational effects however, paternal contributions are likely to be substantial. We focus on the latest advances in understanding the mechanisms of epigenetic inheritance of obesity-evoked metabolic and neurobiological changes through the paternal germline that predict wide-ranging consequences for the following generation(s).
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.TICS.2019.01.005
Abstract: In the modern obesogenic environment, limiting calorie-dense food consumption is partially dependent on the capacity of in iduals to override visceral reactions to hyperpalatable and rewarding food cues. In the current review, we employ a health neuroscience framework to outline: (i) how in idual variations in prefrontal cortical structure and functionality, and by extension, executive functions, may predispose an in idual to the overconsumption of appetitive calorie-dense foods via differences in dietary self-regulation (ii) how obesity may result in changes to cortical structure and functionality and (iii) how the relationship between the structure and function of the prefrontal cortex and obesity may be best described as reciprocal in nature.
Publisher: Springer Science and Business Media LLC
Date: 09-05-2013
DOI: 10.1038/NPP.2013.112
Publisher: Society for Neuroscience
Date: 28-08-2013
Publisher: Springer Science and Business Media LLC
Date: 28-02-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8FO02118J
Abstract: A hypercaloric diet given to adolescent rats induces social memory deficits and reduced neurochemical markers of normal social development.
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.NLM.2013.05.005
Abstract: Frontotemporal lobe dementia (FTD) is a heterogeneous range of disorders, a subset of which arise from fully penetrant, autosomal dominant point mutations in the gene coding for the microtubule associated protein tau. These genetic tauopathies are associated with complex behavioural/cognitive disturbances, including compromised executive function. In the present study, we modelled the effects of the FTD with Parkinsonism linked to chromosome 17 (FTDP-17) tauV337M mutation (known as the Seattle Family A mutation) expressed in mice on executive processes using a novel murine analogue of the Stroop task. Employing biconditional discrimination procedures, Experiment 1 showed that normal mice, but not mice with excitotoxic lesions of the medial prefrontal cortex, were able to use context cues to resolve response conflict generated by incongruent stimulus compounds. In contrast to predictions, response conflict resolution was not disrupted by the tauV337M mutation (Experiment 2). However, while context appropriate actions were goal-directed in wild-type mice, performance of tauV337M mice was not goal-directed (Experiment 3). The results indicate that the tauV337M mutation in mice disrupts, selectively, a subset of processes related to executive function.
Publisher: Wiley
Date: 14-12-2021
Publisher: Frontiers Media SA
Date: 27-08-0004
Publisher: Elsevier BV
Date: 02-2015
DOI: 10.1016/J.BBR.2014.10.011
Abstract: Memories are not static imprints of past experience, but rather are dynamic entities which enable us to predict outcomes of future situations and inform appropriate behaviours. In order to maintain the relevance of existing memories to our daily lives, memories can be updated with new information via a process of reconsolidation. In this review we describe recent experimental advances in the reconsolidation of both appetitive and aversive memory, and explore the neuronal mechanisms that underpin the conditions under which reconsolidation will occur. We propose that a prediction error signal, originating from dopaminergic midbrain neurons, is necessary for destabilisation and subsequent reconsolidation of a memory.
Publisher: Cold Spring Harbor Laboratory
Date: 16-03-0015
Abstract: In this study we sought to determine the effect of daily sucrose consumption in young rats on their subsequent performance in tasks that involve the prefrontal cortex and hippoc us. High levels of sugar consumption have been associated with the development of obesity, however less is known about how sugar consumption influences behavioral control and high-order cognitive processes. Of particular concern is the fact that sugar intake is greatest in adolescence, an important neurodevelopmental period. We provided sucrose to rats when they were progressing through puberty and adolescence. Cognitive performance was assessed in adulthood on a task related to executive function, a rodent analog of the Stroop task. We found that sucrose-exposed rats failed to show context-appropriate responding during incongruent stimulus compounds presented at test, indicative of impairments in prefrontal cortex function. Sucrose exposed rats also showed deficits in an on object-in-place recognition memory task, indicating that both prefrontal and hippoc al function was impaired. Analysis of brains showed a reduction in expression of parvalbumin-immunoreactive GABAergic interneurons in the hippoc us and prefrontal cortex, indicating that sucrose consumption during adolescence induced long-term pathology, potentially underpinning the cognitive deficits observed. These results suggest that consumption of high levels of sugar-sweetened beverages by adolescents may also impair neurocognitive functions affecting decision-making and memory, potentially rendering them at risk for developing mental health disorders.
Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/J.BBR.2017.03.029
Abstract: Excessive consumption of sugar sweetened drinks is proposed to produce functional changes in the hippoc us and prefrontal cortex, leading to perturbations in behavioural control. Impairments in behavioural control have been observed in obese people on tasks that involve making choices, including delay-discounting, indicative of increased impulsivity. In this study we examined the impact of 2h daily access to 10% sucrose (or no sucrose in controls) in young male rats on behavioural tasks reliant on hippoc al function including delay-discounting, T-maze forced choice alternation and place recognition memory, as well as progressive ratio to measure motivation. We observed deficits in place recognition memory and T-maze forced choice alternation, indicative of hippoc al deficits in rats with a history of sucrose consumption. Moreover, rats with a history of sucrose consumption were less motivated to lever press for rewards on a progressive ratio schedule. However, rats with a history of sucrose consumption performed equally to control animals during the delay-discounting task, suggesting that they discounted for reward size over a delay in a manner comparable to control animals. These findings indicate that high-sucrose diets impact on spatial and working memory processes, but do not induce impulsive-like choice behaviours in rats, suggesting that unhealthy diet choices may not influence this aspect of decision-making behaviour.
Publisher: Frontiers Media SA
Date: 27-11-2019
Publisher: Informa UK Limited
Date: 22-11-2020
Publisher: Springer Science and Business Media LLC
Date: 15-11-2016
DOI: 10.1038/MP.2016.193
Abstract: Overconsumption of high-fat diets (HFDs) can critically affect synaptic and cognitive functions within telencephalic structures such as the medial prefrontal cortex (mPFC). The underlying mechanisms, however, remain largely unknown. Here we show that adolescence is a sensitive period for the emergence of prefrontal cognitive deficits in response to HFD. We establish that the synaptic modulator reelin (RELN) is a critical mediator of this vulnerability because (1) periadolescent HFD (pHFD) selectively downregulates prefrontal RELN
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.NEUBIOREV.2017.10.014
Abstract: Obesity is an increasing problem in young people. Childhood obesity and overweight have increased rapidly on a global scale, and have tripled in the past 30 years, to affect approximately one in five children. Diets high in refined fats and sugar are a major contributor to the development of obesity, and the effects of such obesity-inducing hypercaloric diets on brain function may contribute to the high prevalence of anxiety disorders in people with obesity. Anxiety disorders typically emerge in childhood and adolescence, and symptoms often continue into adulthood. Based on this symptomology, we consider anxiety-related behavioral consequences of hypercaloric diets across development. We review research on the effects of hypercaloric dietary manipulations across the lifespan on emotion regulation and the neurobiological mechanisms that underpin these processes. Cumulatively, the findings reveal that gestation and the juvenile/adolescent developmental periods may be early-life windows of vulnerability for developing anxiety in later life due to the augmented effects of these diets on neuroendocrine stress systems and the maturation of neural circuitry supporting emotion regulation.
Publisher: Center for Open Science
Date: 08-2022
Abstract: Concussion, sometimes called a mild traumatic brain injury (mTBI), is an acquired brain injury resulting in alterations to brain function underpinned by a sequence of neuropathological and neurometabolic events that can result in excitotoxicity, oxidative stress, oedema, neuroinflammation and cell death. To date, pharmaceutical therapies have had limited success in treating TBI, presenting considerable interest in nutritional therapies in the form of dietary supplementation to alleviate the deleterious pathological sequelae following neurotrauma. Many nutritional supplements have low toxicity, few drug interactions, and are already approved for human use making them attractive potential therapies following a concussion. In the setting of brain injury models, a considerable body of preclinical evidence has accumulated supporting the use of nutritional supplements including essential fatty acids, vitamins, minerals, amino acids, polyphenols, bioflavonoids and other bioactive compounds to facilitate aspects of functional recovery. Here, we review studies presenting diet supplements as therapeutic strategies as potential treatments for mTBI or to augment neurological resistance against mTBI in experimental models, as well as emerging therapeutic targets including the gut microbiome, and psychedelic and non-psychedelic compounds derived from fungi.
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.PHYSBEH.2016.01.036
Abstract: Excessive consumption of sugar sweetened drinks is proposed to produce functional changes in the hippoc us, leading to perturbations in learning and memory. In this study we examined the impact of 2h daily access to 10% sucrose (or no sucrose in controls) on recognition memory tasks in young male and female rats. In Experiment 1 we tested rats on memory tasks reliant on the hippoc us (place recognition), perirhinal cortex (object recognition), and a combination of hippoc us, prefrontal cortex and perirhinal cortex (object-in-place memory). Exposure to sucrose for 2h a day for 14days prior to behavioral testing did not affect object recognition, but impaired spatial memory to an extent in both male and female rats. Male rats exposed to sucrose were impaired at both place recognition and object-in-place recognition, however female rats showed no impairment in object-in-place performance. Plasticity within the hippoc us is known to increase during the proestrus phase of the estrous cycle and is related to higher levels of circulating estrogens. In Experiment 2 we tested place recognition and object-in-place memory in 10% sucrose exposed or non-exposed control female rats both during the metestrus (low estrogen) and proestrus (high estrogen) phases of their cycle on place recognition and object-in-place memory. Both sucrose exposed and control female rats were able to perform place object-in-place recognition correctly during metestrus and proestrus, however sucrose exposed rats were only able to perform place recognition correctly during proestrus. This indicates that when hippoc al function is compromised, endogenous estrogens may boost memory performance in females, and that males may be at more risk of high sugar diet induced cognitive deficits.
Publisher: Frontiers Media SA
Date: 13-10-2016
Publisher: Society for Neuroscience
Date: 23-01-2019
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.NLM.2011.05.001
Abstract: Instrumental performance in rats with hippoc al lesions is insensitive to the degradation of action-outcome contingencies, but sensitive to the effects of selective devaluation by satiation. One interpretation of this dissociation is that damage to the hippoc us impairs the formation of context-outcome associations upon which the effect of contingency degradation, but not selective satiation, relies. Here, we provide a direct assessment of this interpretation, and showed that conditioned responding to contexts did not show sensitivity to selective satiation (Experiment 1), and confirmed that instrumental performance was sensitive to selective satiation (Experiment 2) following hippoc al cell loss.
Publisher: Springer New York
Date: 2015
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 05-2020
Publisher: Elsevier BV
Date: 08-2018
Publisher: Frontiers Media SA
Date: 21-11-2016
Publisher: Frontiers Media SA
Date: 19-05-2017
Publisher: Cold Spring Harbor Laboratory
Date: 21-12-2012
Abstract: Despite extensive evidence that appetitive memories undergo reconsolidation, two notable failures to observe reconsolidation have been reported: instrumental responding and goal-tracking. However, these studies do not provide conclusive evidence for a lack of memory reconsolidation due to the numerous boundary conditions that dictate whether a memory will undergo reconsolidation. In this study we sought to reexamine reconsolidation in an appetitive, Pavlovian conditioned approach procedure and the behavioral boundary conditions within which memories are destabilized and reconsolidated. This study demonstrated that a Pavlovian goal-tracking memory, previously thought to be resistant to destabilization, will undergo memory reconsolidation under discrete conditions that favor reconsolidation as opposed to extinction, and that this is dependent on the amount of training rats received. With restricted training, systemic administration of MK-801 impaired memory extinction. In contrast, with more extended training, MK-801 administration impaired memory reconsolidation. We also demonstrate that behavioral boundary conditions that exist for appetitive memory reconsolidation are much more complex than simple parametric calculations. Moreover, extinction per se is not a boundary on reconsolidation, in that MK-801 also has no behavioral effect under some conditions.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.PHYSBEH.2016.01.038
Abstract: Adolescents are the highest consumers of sugar sweetened drinks. Excessive consumption of such drinks is a likely contributor to the development of obesity and may be associated with enduring changes in the systems involved in reward and motivation. We examined the impact of daily sucrose consumption in young male and female rats (N=12 per group) across the adolescent period on the motivation to perform instrumental responses to gain food rewards as adults. Rats were or were not exposed to a sucrose solution for 2 h each day for 28 days across adolescence [postnatal days (P) 28-56]. They were then trained as adults (P70 onward) to lever press for a palatable 15% cherry flavored sucrose reward and tested on a progressive ratio (PR) schedule to assess motivation to respond for reinforcement. Female rats exposed to sucrose had higher breakpoints on the PR schedule than controls, whereas male rats exposed to sucrose had lower breakpoints than controls. These results show that consumption of sucrose during adolescence produced sex-specific behavioral changes in responding for sucrose as adults.
Publisher: Wiley
Date: 11-2015
DOI: 10.1111/BPH.13321
Publisher: Springer Science and Business Media LLC
Date: 13-12-2012
DOI: 10.1007/S00213-012-2934-3
Abstract: Discrepancies in an expected outcome have been demonstrated to result in modification of behaviour in both appetitive and aversive conditioning settings. In this study, we sought to establish whether overexpectation generated from compound conditioning with two previously rewarded stimuli was able to induce memory destabilisation and subsequent reconsolidation in a Pavlovian conditioned approach setting. It was shown that 4 days, but not 1 day, of overexpectation training was required to induce memory reconsolidation, and this was disrupted by application of the NMDA subtype of glutamate receptor antagonist MK-801 prior to overexpectation training, but not by MK-801 application 6 h post-training. These data provide evidence that the memories underlying Pavlovian conditioned approach do undergo reconsolidation and that such reconsolidation can be triggered by overexpectation. Therefore, the updating of appetitive conditioned stimulus and unconditioned stimulus associations underpinning conditioned responding in manners other than extinction training is likely achieved through memory reconsolidation.
Publisher: Elsevier BV
Date: 08-2021
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.NEUBIOREV.2014.12.002
Abstract: Changes in food composition and availability have contributed to the dramatic increase in obesity over the past 30-40 years in developed and, increasingly, in developing countries. The brain plays a critical role in regulating energy balance. Some human studies have demonstrated increased preference for high fat and high sugar foods in people reporting greater stress exposure. We have examined neurochemical changes in the brain in rodent models during the development of obesity, including the impact of obesity on cognition, reward neurocircuitry and stress responsiveness. Using supermarket foods high in fat and sugar, we showed that such a diet leads to changes in neurotransmitters involved in the hedonic appraisal of foods, indicative of an addiction-like capacity of foods high in fat and/or sugar. Importantly, withdrawal of the palatable diet led to a stress-like response. Furthermore, access to this palatable diet attenuated the physiological effects of acute stress (restraint), indicating that it could act as a comfort food. In more chronic studies, the diet also attenuated anxiety-like behavior in rats exposed to stress (maternal separation) early in life, but these rats may suffer greater metabolic harm than rats exposed to the early life stressor but not provided with the palatable diet. Impairments in cognitive function have been associated with obesity in both people and rodents. However, as little as 1 week of exposure to a high fat, high sugar diet selectively impaired place but not object recognition memory in the rat. Excess sugar alone had similar effects, and both diets were linked to increased inflammatory markers in the hippoc us, a critical region involved in memory. Obesity-related inflammatory changes have been found in the human brain. Ongoing work examines interventions to prevent or reverse diet-induced cognitive impairments. These data have implications for minimizing harm caused by unhealthy eating.
Publisher: Cold Spring Harbor Laboratory
Date: 15-01-2014
Abstract: Three experiments used rats to examine the effect of a single bout of voluntary activity (wheel running) on the acquisition, extinction, and reconsolidation of context conditioned fear. In Experiment 1, rats provided with access to a wheel for 3 h immediately before or after a shocked exposure to a context froze more when tested in that context than rats provided with access to the wheels 6 h after the shocked exposure or rats not provided with access to the wheels. In Experiment 2, rats provided with access to the wheels immediately before or after a nonshocked exposure to the conditioned context froze less when tested in that context than rats provided with access to the wheels 6 h after the nonshocked exposure or rats not provided with access to the wheels. In Experiment 3, rats provided with access to wheels immediately after an extended nonshocked exposure to the conditioned context again froze less, whereas rats provided with access to the wheels after a brief nonshocked exposure froze more on the subsequent test than sedentary controls. These results show that a single bout of running can enhance acquisition, extinction, and reconsolidation of context conditioned fear.
Publisher: Wiley
Date: 12-2017
DOI: 10.1002/BDR2.1173
Abstract: Adolescence is a significant period of physical, social, and emotional development, and is characterized by prominent neurobiological changes in the brain. The maturational processes that occur in brain regions responsible for cognitive control and reward seeking may underpin excessive consumption of palatable high fat and high sugar "junk" foods during adolescence. Recent studies have highlighted the negative impact of these foods on brain function, resulting in cognitive impairments and altered reward processing. The increased neuroplasticity during adolescence may render the brain vulnerable to the negative effects of these foods on cognition and behavior. In this review, we describe the mechanisms by which junk food diets influence neurodevelopment during adolescence. Diet can lead to alterations in dopamine-mediated reward signaling, and inhibitory neurotransmission controlled by γ-aminobutyric acid (GABA), two major neurotransmitter systems that are under construction across adolescence. We propose that poor dietary choices may derail the normal adolescent maturation process and influence neurodevelopmental trajectories, which can predispose in iduals to dysregulated eating and impulsive behaviors.
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.PHYSBEH.2018.02.027
Abstract: High sucrose diets (HSDs) have been shown to have detrimental effects on hippoc al dependent memory in rats, including the performance of spatial tasks reliant on pattern separation, a cognitive process involved in minimising interference during memory encoding. As such we sought to investigate the impact of HSDs on object and spatial recognition tasks that varied the cognitive load placed on pattern separation processes. Young male and female rats were 4 weeks old at the start of diet manipulations. Rats in the HSD condition were provided with daily access to 10% sucrose solution for 2 h per day across a 28 d period, during which they were assessed on their performance of memory tasks that varied the similarity of spatial arrangements (Spontaneous Location Recognition, SLR) and object features (Novel Object Recognition, NOR) to determine the effect of HSD on memory encoding processes. Both female and male rats that consumed HSDs were impaired at NOR when objects shared multiple features (s-NOR), however when objects were distinct, novel object recognition was not impacted by HSD consumption. Male rats in the control condition generally outperformed female rats in the SLR task when there were small spatial separations (s-SLR) but not when there were large spatial separations (d-SLR). HSD consumption disrupted performance of d-SLR in female rats, but not male rats. Specific HSD deficits were observed in HSD consuming male rats in the s-SLR task. However, the volume of sucrose consumed differed between sexes, and may have impacted memory differentially. These findings indicate that HSD-induced memory deficits may extend to pattern separation dependent recognition memory mechanisms when objects share overlapping features, and impairments in spatial tasks may be more pronounced in female rats.
Publisher: Cold Spring Harbor Laboratory
Date: 17-06-2016
Abstract: High sugar diets reduce hippoc al neurogenesis, which is required for minimizing interference between memories, a process that involves “pattern separation.” We provided rats with 2 h daily access to a sucrose solution for 28 d and assessed their performance on a spatial memory task. Sucrose consuming rats discriminated between objects in novel and familiar locations when there was a large spatial separation between the objects, but not when the separation was smaller. Neuroproliferation markers in the dentate gyrus of the sucrose-consuming rats were reduced relative to controls. Thus, sucrose consumption impaired aspects of spatial memory and reduced hippoc al neuroproliferation.
Publisher: Wiley
Date: 15-12-2021
DOI: 10.1002/HIPO.23291
Abstract: Intrauterine growth restriction (IUGR) is associated with hippoc al alterations that can increase the risk of short-term memory impairments later in life. Despite the role of hippoc al neurogenesis in learning and memory, research into the long-lasting impact of IUGR on these processes is limited. We aimed to determine the effects of IUGR on neuronal proliferation, differentiation and morphology, and on memory function at adolescent equivalent age. At embryonic day (E) 18 (term ∼E22), placental insufficiency was induced in pregnant Wistar rats via bilateral uterine vessel ligation to generate IUGR offspring (n = 10) control offspring (n = 11) were generated via sham surgery. From postnatal day (P) 36-44, spontaneous location recognition (SLR), novel object location and recognition (NOL, NOR), and open field tests were performed. Brains were collected at P45 to assess neurogenesis (immunohistochemistry), dendritic morphology (Golgi staining), and brain-derived neurotrophic factor expression (BDNF Western blot analysis). In IUGR versus control rats there was no difference in object preference in the NOL or NOR, the similar and dissimilar condition of the SLR task, or in locomotion and anxiety-like behavior in the open field. There was a significant increase in the linear density of immature neurons (DCX+) in the subgranular zone (SGZ) of the dentate gyrus (DG), but no difference in the linear density of proliferating cells (Ki67+) in the SGZ, nor in areal density of mature neurons (NeuN+) or microglia (Iba-1+) in the DG in IUGR rats compared to controls. Dendritic morphology of dentate granule cells did not differ between groups. Protein expression of the BDNF precursor (pro-BDNF), but not mature BDNF, was increased in the hippoc us of IUGR compared with control rats. These findings highlight that while the long-lasting prenatal hypoxic environment may impact brain development, it may not impact hippoc al-dependent learning and memory in adolescence.
Publisher: Springer Science and Business Media LLC
Date: 12-2019
DOI: 10.1186/S12888-019-2403-1
Abstract: Cannabis is the most widely used illicit substance by Australian young people, including those engaged with youth alcohol and other drug (AOD) systems. While recreational cannabis use in young people may be a developmental activity for some, for others, this usage becomes regular and be associated with poorer long term outcomes. This study reports on the rates of cannabis use and co-existing psychosocial complexity factors in the Youth Needs Census (2013 and 2016) where workers report on all clients in the youth AOD system, a cohort considered highly vulnerable. Data was examined for two rounds of data collection for the Youth Needs Census, including 823 youth AOD service engaged young people in 2016 and 1000 AOD service engaged young people in 2013, to identify usage rates, psychosocial outcomes, and changes over time. Daily use of cannabis alone significantly exceeded daily usage rates for meth hetamines, alcohol, and cannabis used alongside other substances. Daily cannabis use was significantly associated with mental health problems, employment problems, education problems, family problems, and housing problems. Daily cannabis use was associated with most psychosocial complexity factors to the same extent as daily meth hetamine use and daily alcohol use, with daily cannabis users only showing lower incidence of the drug-related harm measure. Notably, daily cannabis use also increased from 2013 (47.5%) to 2016 (54.2%). It is imperative that the number of in iduals using cannabis is considered alongside the severity of harm when assessing the social impact of this substance. Within cannabis users engaged with the youth AOD system, who often have high levels of psychosocial complexity, cannabis is used daily by a large proportion of these youths and may play a role in negatively impacting their lives.
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.NLM.2016.10.002
Abstract: Anxiety disorders and obesity are both common in youth and young adults. Despite increasing evidence that over-consumption of palatable high-fat/high-sugar "junk" foods leads to adverse neurocognitive outcomes, little is known about the effects of palatable diets on emotional memories and fear regulation. In the present experiments we examined the effects of daily 2h consumption of a high-fat/high-sugar (HFHS) food across adolescence on fear inhibition and anxiety-like behaviour in young adult rats. Rats exposed to the HFHS diet exhibited impaired retention of fear extinction and increased anxiety-like behaviour in an emergence test compared to rats fed a standard diet. The HFHS-fed rats displayed diet-induced changes in prefrontal cortex (PFC) function which were detected by altered expression of GABAergic parvalbumin-expressing inhibitory interneurons and the stable transcription factor ΔFosB which accumulates in the PFC in response to chronic stimuli. Immunohistochemical analyses of the medial PFC revealed that animals fed the HFHS diet had fewer parvalbumin-expressing cells and increased levels of FosB/ΔFosB expression in the infralimbic cortex, a region implicated in the consolidation of fear extinction. There was a trend towards increased IBA-1 immunoreactivity, a marker of microglial activation, in the infralimbic cortex after HFHS diet exposure but expression of the extracellular glycoprotein reelin was unaffected. These findings demonstrate that a HFHS diet during adolescence is associated with reductions of prefrontal parvalbumin neurons and impaired fear inhibition in adulthood. Adverse effects of HFHS diets on the mechanisms of fear regulation may precipitate a vulnerability in obese in iduals to the development of anxiety disorders.
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.TINS.2019.04.003
Abstract: The relationship between neurons and perineuronal nets (PNNs) is attracting attention as a central mechanism controlling brain plasticity. In the cortex, PNNs primarily surround inhibitory parvalbumin interneurons, playing roles as both a regulator of synaptic plasticity and a protective barrier. PNNs have a delayed developmental trajectory and are key components in the closure of critical periods of heightened neuroplasticity. In animal models, manipulating PNNs outside this critical window can enhance cognition, suggesting a potentially therapeutic approach for attenuating cognitive decline. However, the crucial role of PNNs in plasticity and protection means that such therapeutic modulation must strike a careful balance: manipulation of PNNs to promote plasticity may have unintended negative consequences resulting from excessive plasticity or from exposure of neurons to neurotoxins.
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.NEUROPHARM.2018.04.012
Abstract: Caffeinated sugar-sweetened "energy" drinks are a subset of soft drinks that are popular among young people worldwide. High sucrose diets impair cognition and alter aspects of emotional behaviour in rats, however, little is known about sucrose combined with caffeine. Rats were allocated to 2 h/day 10% sucrose (Suc), 10% sucrose plus 0.04% caffeine (CafSuc) or control (water) conditions. The addition of caffeine to sucrose appeared to increase the rewarding aspect of sucrose, as the CafSuc group consumed more solution than the Suc group. After 14 days of intermittent Suc or CafSuc access, anxiety was assessed in the elevated plus maze (EPM) prior to their daily solution access, whereby CafSuc and Suc rats spent more time in the closed arms, indicative of increased anxiety. Following daily solution access, CafSuc, but not Suc, rats showed reduced anxiety-like behaviour in the open-field. Control and CafSuc rats displayed intact place and long-term object memory, while Suc showed impaired memory performance. Sucrose reduced parvalbumin immunoreactivity in the hippoc us, but no differences were observed between Control and CafSuc conditions. Parvalbumin reactivity in the basolateral amygdala did not differ between conditions. Reduced doublecortin immunoreactivity in the dentate gyrus relative to controls was seen in the CafSuc, but not Suc, treatment conditions. These findings indicate that the addition of caffeine to sucrose attenuated cognitive deficits. However, the addition of caffeine to sucrose evoked anxiety-like responses under certain testing conditions, suggesting that frequent consumption of caffeinated energy drinks may promote emotional alterations and brain changes compared to standard soft drinks.
Publisher: Elsevier BV
Date: 2015
DOI: 10.1016/J.BBI.2014.07.005
Abstract: Both obesity and over-consumption of palatable high fat/high sugar "cafeteria" diets in rats has been shown to induce cognitive deficits in executive function, attention and spatial memory. Adult male Sprague-Dawley rats were fed a diet that supplemented standard lab chow with a range of palatable foods eaten by people for 8 weeks, or regular lab chow. Memory was assessed using a trace fear conditioning procedure, whereby a conditioned stimulus (CS) is presented for 10s and then 30s after its termination a foot shock (US) is delivered. We assessed freezing to the CS (flashing light) in a neutral context, and freezing in the context associated with footshock. A dissociation was observed between levels of freezing in the context and to the CS associated with footshock. Cafeteria diet fed rats froze less than control chow fed rats in the context associated with footshock (P<0.01), indicating that encoding of a hippoc us-dependent context representation was impaired in these rats. Conversely, cafeteria diet fed rats froze more (P<0.05) to the CS than chow fed rats, suggesting that when hippoc al function was compromised the cue was the best predictor of footshock, as contextual information was not encoded. Dorsal hippoc al mRNA expression of inflammatory and neuroplasticity markers was analysed at the end of the experiment, 10 weeks of diet. Of these, mRNA expression of reelin, which is known to be important in long term potentiation and neuronal plasticity, was significantly reduced in cafeteria diet fed rats (P=0.003). This implicates reductions in hippoc al plasticity in the contextual fear memory deficits seen in the cafeteria diet fed rats.
Publisher: SAGE Publications
Date: 16-09-2013
Abstract: Previous research demonstrates that disruption of forebrain dopamine systems impairs the use of high-order information to guide goal-directed performance, and that this deficit may be related to impaired use of task-setting cues in patients with schizophrenia. Such deficits can be interrogated through conflict resolution, which has been demonstrated to be sensitive to prefrontal integrity in rodents. We sought to examine the effects of acute systemic d- hetamine administration on the contextual control of response conflict in rats, and whether deficits were reversed through pre-treatment with clozapine or the D 1 /D 2 antagonist α-flupenthixol. Acute d- hetamine (1.5 mg/kg) disrupted the utilisation of contextual cues therefore rats were impaired during presentation of stimulus compounds that require conflict resolution. Evidence suggested that this effect was attenuated through pre-treatment with the atypical antipsychotic clozapine (5.0 mg/kg), but not the typical antipsychotic α-flupenthixol (0.25 mg/kg), at doses previously shown to attenuate d- hetamine-induced cognitive deficits. These studies therefore demonstrate a potentially viable model of disrupted executive function such as that seen in schizophrenia.
Publisher: Cambridge University Press (CUP)
Date: 13-04-2021
DOI: 10.1017/S2040174420000227
Abstract: Infant colic is a condition of unknown cause which can result in carer distress and attachment difficulties. Recent studies have implicated the gut microbiota in infant colic, and certain probiotics have demonstrated possible efficacy. We aim to investigate whether the intestinal microbiota composition in infants with colic is associated with cry/fuss time at baseline, persistence of cry/fuss at 4-week follow-up, or child behavior at 2 years of age. Fecal s les from infants with colic (n = 118, 53% male) were analyzed using 16S rRNA sequencing. After examining the alpha and beta ersity of the clinical s les, we performed a differential abundance analysis of the 16S data to look for taxa that associate with baseline and future behavior, while adjusting for potential confounding variables. In addition, we used random forest classifiers to evaluate how well baseline gut microbiota can predict future crying time. Alpha ersity of the fecal microbiota was strongly influenced by birth mode, feed type, and child gender, but did not significantly associate with crying or behavioral outcomes. Several taxa within the microbiota (including Bifidobacterium, Clostridium, Lactobacillus, and Klebsiella ) associate with colic severity, and the baseline microbiota composition can predict further crying at 4 weeks with up to 65% accuracy. The combination of machine learning findings with associative relationships demonstrates the potential prognostic utility of the infant fecal microbiota in predicting subsequent infant crying problems.
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.NEUROPHARM.2011.01.024
Abstract: Schizophrenia and autistic spectrum disorder (ASD) are common, chronic mental conditions with both genetic and environmental components to their aetiology. The identification of genes influencing susceptibility to these disorders offers a rational route towards a clearer understanding of the neurobiology, and with this the prospect of treatment and prevention strategies tailored towards the remediation of the altered pathways. Copy number variants (CNVs) underlie many serious illnesses, including neurological and neurodevelopmental syndromes. Recent studies assessing copy number variation in ASD and schizophrenia have repeatedly observed heterozygous deletions eliminating exons of the neurexin-1α gene (but not the neurexin-1β gene) in patients with ASD and schizophrenia. The neurexins are synaptic adhesion proteins that are known to play a key role in synaptic formation and maintenance. The functional significance of the recurrent deletion is poorly understood, but the availability of mice with deletion of the promoter and first exon of neurexin-1α provides direct access to the biological effects of neurexin-1α disruption on phenotypes relevant to ASD and schizophrenia. We review the evidence for the role of neurexin-1α in schizophrenia and ASD, and consider how genetic disruption of neurexin-1α may underpin the neuropathology contributing to these distinct neurodevelopmental disorders.
Publisher: Frontiers Media SA
Date: 2013
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2019
End Date: 2021
Funder: Australian Research Council
View Funded ActivityStart Date: 2018
End Date: 2020
Funder: Canada First Research Excellence Fund
View Funded ActivityStart Date: 2018
End Date: 2021
Funder: National Health and Medical Research Council
View Funded ActivityStart Date: 2019
End Date: 12-2022
Amount: $428,724.00
Funder: Australian Research Council
View Funded ActivityStart Date: 02-2014
End Date: 12-2017
Amount: $375,000.00
Funder: Australian Research Council
View Funded Activity