THE NEUROBIOLOGICAL BASIS OF INDIVIDUAL DIFFERENCES IN SUSCEPTIBILITY TO THE CONSEQUENCES OF STRESS
Funder
National Health and Medical Research Council
Funding Amount
$583,875.00
Summary
Stress plays a major role in the development and progression of many different mental health disorders. However, as we all know, the effects of stress on one person can be very different from its effects upon another. This is at least partly explained by differences in individual coping styles. When faced with a stressful situation without a ready solution, people tend to divide into two broad camps: those with an innate tendency to adopt passive coping strategies, such as avoidance, and those t ....Stress plays a major role in the development and progression of many different mental health disorders. However, as we all know, the effects of stress on one person can be very different from its effects upon another. This is at least partly explained by differences in individual coping styles. When faced with a stressful situation without a ready solution, people tend to divide into two broad camps: those with an innate tendency to adopt passive coping strategies, such as avoidance, and those that tend towards active coping strategies, such as attempting to take control of the situation. Previous studies have provided findings that suggest that passive coping is more common amongst sufferers of depression, post-traumatic stress disorder, and chronic pain syndrome than is active coping. But is this cause, or effect? And what are the intervening brain mechanisms? We attempt to address such questions in the present project using an animal model in which social conflict has been shown to trigger depression-like symptoms. In particular we wish to: (i) determine whether the patterns of brain activity triggered by social conflict are different for active vs. passive copers; (ii) determine whether the depression-like consequences of social conflict are more severe in passive than in active copers; (iii) determine whether differences in coping style and vulnerability to social conflict stress are due to the actions of a particular neurotransmitter, dopamine, in the prefrontal cortex of the brain; (iv) determine whether the actions of antidepressants might be attributable changes in prefrontal cortex dopamine function which in turn promote active coping in preference to passive coping. These studies will provide exciting new information about the neurobiological basis of individual differences in vulnerability to the harmful effects of stress, and thus will offer the hope of developing new ways of preventing devastating illnesses such as depression.Read moreRead less
Dopamine Mechanisms Conferring Resilience To Depression: A New Antidepressant Target
Funder
National Health and Medical Research Council
Funding Amount
$560,948.00
Summary
A significant proportion of people who suffer depression fail to obtain effective relief from either drugs or psychotherapy. Accordingly, there is a pressing need to develop new, and more effective, treatments. This project will determine whether certain specific brain pathways that use the transmitter dopamine can be manipulated in their activity so as to increase resilience to depression. This work has potential to provide the foundation for the development a new generation of antidepressants.
Methamphetamine-induced Habits And The Re-establishment Of Behavioural Control.
Funder
National Health and Medical Research Council
Funding Amount
$577,079.00
Summary
The aim of this project is to understand the neural bases of drug addiction, specifically methamphetamine addiction, particularly the changes in neural processes that render drug seeking compulsive. We aim to establish the physical and chemical changes in the brain that cause the changes in decision making induced by exposure to drugs of abuse, most notably the changes that result in a loss of behavioural control.
The Neurochemical Basis Of Behavioural Control: Relevance For Addiction, OCD And Tourette Syndrome.
Funder
National Health and Medical Research Council
Funding Amount
$375,225.00
Summary
Both the control of voluntry responses over reflexive habits, and the ability to direct voluntary responses appropriately when there are conflicting choices present in the world, are thought to be important in mental disorders such as drug addiction, tic disorders such as Tourette syndrome and obsessive compulsive disorder. This project will examine the brain neurochemistry that underpins our ability to control voluntary responses, providing insight into potential pharmacological interventions.
Imaging Genetics In Schizophrenia And Bipolar Disorder: Adjudicating Neurocognitive Endophenotypes
Funder
National Health and Medical Research Council
Funding Amount
$569,873.00
Summary
Schizophrenia and bipolar disorder share some common genes and cognitive deficits, yet manifest differently in terms of symptom expression, illness course, and functional impact. This research tests the assertion that genes implicated as common to these conditions may code for impairments in prefrontal cognitive and sub-cortical emotion processing. We also examine whether between-diagnosis distinctions in these brain responses may be mediated by hypothalamic-pituitary-adrenal axis functioning.
Inhibition Of Fear Memories By Extinction: Neural Substrates.
Funder
National Health and Medical Research Council
Funding Amount
$234,250.00
Summary
Anxiety disorders [e.g., Post Traumatic Stress Disorder (PTSD)] are the most prevalent type of psychopathology in the industrialised world. They are associated with characteristic behavioural (e.g., heightened startle) and autonomic (e.g., cardiovascular) reactions. These disorders are often characterised as an inability to regulate the emotion of fear. Significant progress has been made in understanding the neural and cellular processes involved in the establishment of fear memories, but relati ....Anxiety disorders [e.g., Post Traumatic Stress Disorder (PTSD)] are the most prevalent type of psychopathology in the industrialised world. They are associated with characteristic behavioural (e.g., heightened startle) and autonomic (e.g., cardiovascular) reactions. These disorders are often characterised as an inability to regulate the emotion of fear. Significant progress has been made in understanding the neural and cellular processes involved in the establishment of fear memories, but relatively little is known about the mechanisms by which fear memories can be inhibited or suppressed. Understanding this latter process is a key to the development of effective treatments for anxiety disorders such as PTSD where the patient suffers from persistent, intrusive, unwanted trauma memories. A common experimental procedure for reducing learned fear is to repeatedly expose the subject to a fear-eliciting stimulus but without any aversive outcome. This procedure leads to a progressive loss, or extinction, of the fear reactions elicited by the stimulus. Historically, the extinction of fear was thought to be due to an erasure of the fear memory. However, recent evidence shows that extinction inhibits, rather than erases, the fear memory. Because the fear memories remain intact, some structure(s) in the brain must inhibit activity in the fear pathway. This project uses extinction of conditioned fear reactions in rat subjects to determine the structure(s) in the brain that inhibit fear memories and their behavioural and cardiovascular expression. It brings together the expertise of four well-established researchers and uses a combination of behavioural, physiological, immunohistochemical, tract tracing, and lesion approaches to achieve this aim. The proposed experiments will reveal the structure(s) in the brain that control the inhibition of fear, as well as the site(s) of this inhibition in the fear pathwayRead moreRead less
A decade ago the adult brain was thought of as a structurally-fixed organ. Against this are well-documented cases of slow recovery after massive injuries or stroke. Simple models of brain injury using the tactile, visual and auditory systems of animals as models have now revealed multiple stages of recovery (plasticity). Some of these are inbuilt into the wiring of the neural systems such that functional plasticity can result without the need for any structural or cellular changes. A second grou ....A decade ago the adult brain was thought of as a structurally-fixed organ. Against this are well-documented cases of slow recovery after massive injuries or stroke. Simple models of brain injury using the tactile, visual and auditory systems of animals as models have now revealed multiple stages of recovery (plasticity). Some of these are inbuilt into the wiring of the neural systems such that functional plasticity can result without the need for any structural or cellular changes. A second group of plastic phenomena depend upon minute changes in the connections between neurons and these are invoked in the first few days following an injury (synaptic plasticity; changes in the pattern and strength of the connections between neurons). Aside from being model systems, there are also parallels of this plasticity with clinical situations such as losses in hearing and sight, and of the adaptations made by the brain in response to prosthetics (e.g. bionic ear) and resorative surgery but the degree of relevance for these situations is unclear. An intriguing aspect of the experiments on auditory and visual systems is that neurons with inputs from both ears, or both eyes, undergo the plastic changes when the relevant sense organ on only one side is damaged but the other is intact. In fact, on the basis of the limited available evidence, it appears that the changes are independent of there being a normal input from the other side. This is difficult to explain in terms of the modern understanding neuronal plasticity at a cellular level. It is thus proposed to study both auditory and visual models of this brain plasticity with stimuli which are systematically varied to extract the extent of bilateral interaction in the induced plasticity. This will enable prediction of how these plasticity mechanisms will be involved in adaptations made to prosthetics and surgical corrections.Read moreRead less
Combining input from vision and hearing greatly enhances perception when information from one of these senses is degraded or incomplete, such as when tracking objects in foggy, dark or noisy places. This enhancement is of considerable importance because degraded input is the daily situation faced by many people with hearing or vision impairment. We will study the neural processes underlying our ability to combine vision and hearing to create a more reliable and accurate perception of the world.