The Memory Program investigates the cognitive systems and brain structures underlying various forms of memory, including autobiographical memory, episodic memory, semantic memory, procedural memory, working memory, as well as imagination of future events. To understand these memory systems, researchers use experimental neuropsychological methods, structural and functional brain imaging, and post-mortem investigations from healthy individuals and from patients with progressive brain pathologies, such as dementia, or patients with static brain lesions due to congenital or acquired brain abnormality, or following brain surgery. The Memory Program aims to develop cognitive models of these memory systems and develop ways to measure these processes in humans.
- Autobiographical memories, imagining the future, and prospective memory
- Prospection: A developmental perspective
- Couples as remembering systems: The costs and benefits of remembering with others as we age
- Interactions between emotions and memory
- Memory in the dementias
- Expanding understanding of the mechanisms and brain circuitry of human memory systems
- Interventions for memory and other cognitive deficits
- Memory disorders in children with traumatic brain injury
The episodic memory system enables us to remember personal events from our recent past and distant past. These memories are essential for our sense of self and continuity over time. Our work has demonstrated that the brain's semantic memory system (our memory for facts and general knowledge) provides the scaffolding necessary for the construction of future events, including prospective memory. Prospective memory supports our capacity to carry out intentions at a future time point, enabling us to 'remember to remember', so we can remember to keep appointments, to take medication, or to pick up milk on the way home, as well as our ability to entertain various possible scenarios regarding future events. Several processes are required for successful prospective memory performance, including retrieval of an appropriate action (episodic memory), but also maintenance of a timetable indicating when to carry out this action in the future. We are exploring the neurocognitive mechanisms essential for successful prospective memory performance by studying its breakdown in neurodegenerative disorders. Prospective memory is seriously compromised in patients with frontotemporal dementia, however, different types of impairment are seen depending on the location of brain atrophy. Our findings indicate that dissociable biological mechanisms underpin prospective memory lapses in the different dementia syndromes.
Prospection is the ability to imagine the future. This ability is central for normal daily functioning, as it guides our actions. The first line of our work has revealed marked developmental gains in prospection from childhood to adolescence, which are largely due to increase in relational memory. We are now exploring developmental changes in prospection from adolescence into early adulthood and investigating the biological underpinnings of these changes. The second line of our research examines the impact of childhood brain injuries on prospection. Preliminary findings suggest that children and adolescents who have sustained brain injuries have impoverished ability to construct future events. The third line of our research studies the development of time based prospective memory, the ability to execute intentions at a certain time. We have developed a new computerised task for assessment of time based prospective memory and standardised this task on a group of typically developing children. The task has also been used in a project that examines rehabilitation of prospective memory deficits in children with acquired brain injuries.
This project measures the costs and benefits of remembering together in long-standing family groups. We have worked with healthy, long married older couples (via the Australian Imaging, Biomarkers & Lifestyle Flagship Study of Ageing in Melbourne) and we are currently working with long married older couples where one partner has mild cognitive impairment (via the Alzheimer's Disease Research Centre at Washington University in St Louis). We measure people's ability to recall different kinds of memory material: word lists, information about the world and autobiographical memories from their past. Importantly, we compare these older adults' success in remembering when they work alone versus when they work together with their spouse. Many couples do much better when they recall with their partner, highlighting systems of memory scaffolding developed over a lifetime of living together. We aim to identify the parameters of successful scaffolding, such as the who, what and when of successful memory cues, and we are exploring whether this scaffolding predicts individuals' cognitive trajectories over time. We also focus on the broader systems of memory scaffolding that couples develop within their physical and social environments to understand how to help promote and protect healthy memory, especially as we age.
Emotional events like weddings, funerals or accidents are typically remembered in greater detail and more vividly than non-emotional events. The emotional enhancement of memory depends on brain regions in the frontal and temporal lobes, including the amygdala, hippocampus, insula and prefrontal cortices. The brain regions that contribute to emotional memory enhancement undergo marked atrophy in the common dementia syndromes. Few studies, however, have investigated how emotional enhancement of memory is affected in patients with Alzheimer's disease and frontotemporal dementia. In patients with Alzheimer's disease, episodic memory is profoundly impaired, yet emotional functioning remains relatively intact. In contrast, early impairments in emotional and social functioning are observed in frontotemporal dementia. Our initial findings revealed that emotional enhancement of memory is compromised in frontotemporal dementia. Using neuroimaging we found that this loss of emotional enhancement of memory is associated with atrophy in the orbitofrontal cortex. We are now investigating how the emotional enhancement of memory can be modulated, either enhanced or reduced, in these progressive brain disorders.
Deficits of episodic memory are early and prominent symptoms of Alzheimer's disease. In a series of studies, we have demonstrated that patients with frontotemporal dementia, the second most common form of younger-onset dementia, also have significant impairments in episodic memory. Memory deficits are also observed in other dementia syndromes, including Parkinson's disease. These findings have clinical relevance for the accurate diagnosis of these disorders. Our projects aim to elucidate the nature of the memory problems in patients with dementia of different aetiology (Alzheimer's disease, frontotemporal dementia, Parkinson's disease) as well as in individuals at risk of developing dementia (mild cognitive impairment). We are developing a range of memory tests to differentiate these diseases based on the specific aspects of memory that are impaired and the neural structures that have been found to be affected in these disorders. This approach has improved our ability to characterise memory dysfunction in various disorders and to assess the risk of developing dementia in people with emerging memory problems.
The ability to create long-lasting memories relies on a complex array of processes that require the integration of perceptual, emotional and contextual information. Our research, and that of others, has demonstrated the importance of a number of structures within the medial temporal lobes of the brain, such as the hippocampus, mammillary bodies, fornix, thalamus, cingulate cortex, as well as by the prefrontal cortices. Our recent projects expand on this knowledge by investigating the specific roles of these brain regions during the learning (encoding) and remembering (retrieval) phases of memory. Our results support the view that specific regions within and beyond the medial temporal lobes and thalamus contribute to different types of associative memory processes at the time of encoding and retrieval. Our research also confirms a specialisation within these brain regions when processing verbal or non-verbal information. These projects have variously used structural and functional brain imaging techniques, as well as postmortem investigations, in healthy individuals and in clinical populations, including mild cognitive impairment, dementia (Alzheimer's disease, semantic dementia and frontotemporal dementia), or focal brain lesions (stroke or epilepsy). These investigations of the patterns of memory deficits and associated changes in the brain have contributed to a better understanding of the brain circuitry involved in normal memory processes.
One driving impetus to our research program is its clinical relevance. We are using results from our research to design tests of memory that can allow clinicians to identify deficits more precisely. We are also developing interventions that target specific memory deficits in the clinic and in day-to-day activities. In the recent past, we developed an effective word retraining program for individuals diagnosed with semantic dementia, a disorder characterised by a profound loss of naming and comprehension of word meaning. Despite continuing brain deterioration, patients with semantic dementia experience long-term benefits following the completion of this retraining program. Separately, we are developing electronic tools to help with the assessment of memory and language. These tools are freely available to clinicians and researchers, with the aim to facilitate test administration and promote data collection for research projects and for the general clinical community. Following the electronic version of the Addenbrookes Cognitive Examination, we are about to release our Sydney Language Battery app, which examines aspects of language (naming, comprehension, repetition) in an interactive environment. Under construction is also a web-based version of the Everyday Memory Training Program designed by Drs Laurie Miller, Kylie Radford and Sunny Lah. This program will provide individuals with memory deficits retraining memory techniques in separate modules that can be completed at their own pace. Finally, our collaboration with the School of Design at the University of Technology, Sydney, continues with the aim to develop and trial prototype devices that will help people with memory impairment remember events from their personal past and therefore improve their quality of life by feeling better connected.
We are currently investigating memory disorders and their functional implications in children with traumatic brain injury. We have developed a new scale for assessing memory in the acute stage of recovery following a traumatic brain injury sustained in early to middle childhood. This scale was found to be sensitive to the severity of traumatic brain injury and predictive of disability post-discharge. In children who are in the chronic stage of recovery from traumatic brain injury, we examined working memory, a complex system that comprises a central executive and two storage systems (phonological loop and visuo-spatial sketchpad), which is important for academic learning. We found that various components of the working memory system had differential sensitivity to traumatic brain injury in children. The central executive and phonological loop were vulnerable to disruption, while the visuo-spatial sketchpad was not. Moreover, we undertook a double blind randomised controlled trial of computerised working memory rehabilitation that included school aged children who sustained traumatic brain injury more than a year before. Significant gains in working memory were found on completion of the training. These gains were sustained at 3 months follow-up. Importantly, we found evidence of selective transfer, with significant improvements in reading post-training. The impact of working memory rehabilitation may be greater if implemented during periods when functional reorganisation post-injury is most intense and when the brain is undergoing extensive developmental changes. Thus, in the next stage of our research we plan to implement the training at earlier stages of recovery and include preschool children.
Upcoming CCD Seminars
- Wednesday 22nd Feb,
Dr Dries Trippas,
"Belief bias in syllogistic reasoning: A meta-analysis of ROC data."
- Thursday 23rd Feb,
Dr Edwin Burns,
"Our experiences with faces and language shape face perception."
- Friday 24th Feb,
"Perception of L2 morphophonology by Mandarin learners of English. ..."
- Wednesday 1st Mar,
Professor Ocke-Schwen Bohn,
"Infant directed speech and its implications for language development: ..."
- Wednesday 1st Mar,
Distinguished Professor Douglas H Whalen,
"Characteristics and usefulness of phonetic variability. (CLaS-CCD ..."