Assoc Prof Olivier Piguet

TEAM LEADER PROFILE

Principal Research Fellow, NeuRA Associate Prof, UNSW
Co-Director FRONTIER, Frontotemporal Dementia Research Group, NeuRA
Visiting Clinical Neuropsychologist, Prince of Wales Hospital

+612 9399 1713


Assoc Prof Olivier Piguet trained in psychology in Geneva and obtained a Master’s degree in clinical neuropsychology at the University of Melbourne and a PhD at the University of Sydney. He undertook postdoctoral training at MIT before establishing his research group at Neuroscience Research Australia. He is also a clinical neuropsychologist with 18 years clinical experience, 12 of which dedicated to ageing and neurodegeneration. He has a growing international reputation in the field of cognitive changes associated with healthy and pathological brain ageing and has published over 50 peer-reviewed journal articles on this topic. More recently, his research has focused on the biological correlates underlying changes in emotion processing and memory in frontotemporal dementia. At NeuRA, Assoc Prof Piguet collaborates closely with Prof Hodges and Prof Halliday.

Projects Assoc Prof Olivier Piguet is currently involved with

CURRENT PROJECTS

Episodic memory in FTD

Associative memory in frontotemporal dementia
Associative memory processes are crucial to the formation and retrieval of memories. Associative memory deficits in patients with FTD have not been thoroughly investigated. The aim of this project is to assess associative memory abilities in patients with different subtypes of FTD, patients with Alzheimer’s disease and healthy controls. We are utilising a number of novel associative memory tasks in an attempt to identify subtle deficits in associative memory abilities in these groups. Such tasks may be useful clinically and contribute to improving the diagnostic accuracy of patients with dementia in the early stages of the disease.
Episodic future thinking in frontotemporal dementia
Imagine the next time you will take a holiday abroad. What will you do in a few hours? What will you do next week…next month…next year? Thinking about the future, withdrawing from our current tasks to imagine, daydream, and construct possible future scenarios is something we all engage in. Imagining the future depends on the same neural system that is recruited when remembering the past. When dementia patients experience difficulties remembering the past, is their ability to imagine the future also affected? This study investigates episodic future thinking in frontotemporal dementia, to explore the impact of damage to the episodic memory system and how this affects the ability to conceive of oneself in the future.

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Episodic memory in FTD

Emotion processing in frontotemporal dementia

Emotional memory in frontotemporal dementia
All memories are not created equal. Emotion has a powerful impact on memory with highly emotional events generally remembered with greater detail and vividness than events that lack emotion. The brain regions necessary for both emotion and memory are affected in frontotemporal dementia. Although disturbance of emotion has been reported in frontotemporal dementia, whether it also impacts on memory has not been investigated. This project aims to determine how these emotion and memory interact in FTD, and how they differ across subtypes.
Emotion processes in FTD subtypes
How people interpret and recognize emotions in others is critical for everyday social interactions and the formation and maintenance of interpersonal relationships. Evidence now suggests that the ability to recognise emotions in others is disturbed in frontotemporal dementia. This project aims to investigate how emotion processing is disturbed across subtypes of frontotemporal dementia and determine whether there are ways to improve emotion recognition in these groups. This will help us to understand the mechanisms important for emotion processing, and help to find ways for patients and their families to overcome these difficulties

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Emotion processing in frontotemporal dementia

Eating disturbance in FTD

Marked eating disturbances (e.g., overeating) are common in a subset of patients diagnosed with FTD. Such behaviours have a major impact on patient management and health but their biological causes are poorly understood. Whether the hypothalamus, a structure critical for the regulation of eating behaviours, is affected in FTD is unknown. This project will investigate biological markers of eating disturbance in FTD using blood tests and high resolution neuroimaging.

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Eating disturbance in FTD

Brain imaging

Patterns of white matter changes in frontotemporal dementia subtypes

Brain atrophy is found in specific cortical and subcortical regions in frontotemporal dementia. The pattern of atrophy is specific to each subtype. Although changes in the brain grey matter are well documented, changes in the white matter are not as well understood. This study investigates changes in white matter in FTD subtypes using diffusion tensor imaging, and how these changes are related to those found in the grey matter. This project will also map the evolution of these changes with disease progression.
In vivo and postmortem relations of white matter changes in frontotemporal dementia

Changes in white matter integrity have been reported in FTD on neuroimaging investigations such as MRI, with a particular interest on diffusion tensor imaging (DTI) in recent years. DTI provides a measure of tissue organisation. However, the nature of these changes of the white matter ultrastructure in FTD is unknown. This project will determine the changes in the brain white matter at postmortem in FTD patients for whom DTI was acquired in life. Relations between these changes in the different FTD subtypes will be established.

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Brain imaging

Biological basis of episodic memory

Functional and biological correlates of associative memory

Our ability to create and retrieve specific memories is dependent upon a number of discrete cognitive processes allowing us to create associations between different types of information. These processes are collectively called associative memory. Recent evidence suggests that brain structures within the medial temporal lobe are crucial for different types of associative memory. This project utilises different tasks of associative memory in combination with structural and functional magnetic resonance imaging techniques to investigate the neural correlates of associative memory processes. The goal of this research is to increase our understanding of the contributions of the medial temporal lobe contribute to these processes.

Contributions of prefrontal cortices to episodic memory

Episodic memory refers to our ability to remember events that are located in a particular time and place, for example where you left your car keys, or recalling your first day at school. The importance of the medial temporal lobes (MTL) for forming and retrieving episodic memories is well established, however, less is known regarding the role of the prefrontal cortex (PFC) or the possible interaction between these brain regions. This project investigates episodic memory disruption in frontotemporal dementia, a neurodegenerative disorder affecting both temporal and prefrontal brain regions selectively, providing us with a unique model to investigate the specialised roles of the MTL and PFC in episodic memory and how these systems interact.

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Biological basis of episodic memory

RESEARCH TEAM

Fiona Kumfor

DR FIONA KUMFOR Research Officer

David Foxe

DAVID FOXE Research Assistant

Cassandra Kaizik

CASSANDRA KAIZIK Research Assistant

Cynthia_Murray_DSC_7648

CYNTHIA MURRAY Research Assistant and Registered Psychologist (Neuropsychology)

Rosi Hutchings

ROSI HUTCHINGS PhD Student

Sicong Tu

SICONG TU PhD Student

Stephanie Wong

STEPHANIE WONG PhD Student

Ramon Landin-Romero

RAMON LANDIN-ROMERO Research Officer

Akira Midorikawa

DR AKIRA MIDORIKAWA Visiting

Melissa Abela

DR MELISSA ABELA Donor Co-ordinator

Angela_Scharfenberg_DSC_7645

ANGELA SCHARFENBERG Research Assistant

PUBLICATIONS

Preservation of episodic memory in semantic dementia: The importance of regions beyond the medial temporal lobes.

Irish M, Bunk S, Tu S, Kamminga J, Hodges JR, Hornberger M, Piguet O

Episodic memory impairment represents one of the hallmark clinical features of patients with Alzheimer's disease (AD) attributable to the degeneration of medial temporal and parietal regions of the brain. In contrast, a somewhat paradoxical profile of relatively intact episodic memory, particularly for non-verbal material, is observed in semantic dementia (SD), despite marked atrophy of the hippocampus. This retrospective study investigated the neural substrates of episodic memory retrieval in 20 patients with a diagnosis of SD and 21 disease-matched cases of AD and compared their performance to that of 35 age- and education-matched healthy older Controls. Participants completed the Rey Complex Figure and the memory subscale of the Addenbrooke's Cognitive Examination-Revised as indices of visual and verbal episodic recall, respectively. Relative to Controls, AD patients showed compromised memory performance on both visual and verbal memory tasks. In contrast, memory deficits in SD were modality-specific occurring exclusively on the verbal task. Controlling for semantic processing ameliorated these deficits in SD, while memory impairments persisted in AD. Voxel-based morphometry analyses revealed significant overlap in the neural correlates of verbal episodic memory in AD and SD with predominantly anteromedial regions, including the bilateral hippocampus, strongly implicated. Controlling for semantic processing negated this effect in SD, however, a distributed network of frontal, medial temporal, and parietal regions was implicated in AD. Our study corroborates the view that episodic memory deficits in SD arise very largely as a consequence of the conceptual loading of traditional tasks. We propose that the functional integrity of frontal and parietal regions enables new learning to occur in SD in the face of significant hippocampal and anteromedial temporal lobe pathology, underscoring the inherent complexity of the episodic memory circuitry.

Longitudinal Memory Profiles in Behavioral-Variant Frontotemporal Dementia and Alzheimer's Disease.

Schubert S, Leyton CE, Hodges JR, Piguet O

To compare changes over time in memory, general cognition tasks, and functional scales between bvFTD and AD. Neither the initial neuropsychological assessment nor projected performances can reliably distinguish the totality of bvFTD and AD individuals. Nevertheless, annual rates of progression on cognitive tasks provide valuable information and will potentially help establish the impact of future therapeutic treatments in these dementia syndromes.

Material specific lateralization of medial temporal lobe function: An fMRI investigation.

Dalton MA, Hornberger M, Piguet O

The theory of material specific lateralization of memory function posits that left and right MTL regions are asymmetrically involved in mnemonic processing of verbal and nonverbal material respectively. Lesion and functional imaging (fMRI) studies provide robust evidence for a left MTL asymmetry in the verbal memory domain. Evidence for a right MTL/nonverbal asymmetry is not as robust. A handful of fMRI studies have investigated this issue but have generally utilised nonverbal stimuli which are amenable to semantic elaboration. This fMRI study aimed to investigate the neural correlates of recognition memory processing in 20 healthy young adults (mean age = 26 years) for verbal stimuli and nonverbal stimuli that were specifically designed to minimize verbalisation. Analyses revealed that the neural correlates of recognition memory processing for verbal and nonverbal stimuli were differentiable and asymmetrically recruited the left and right MTL respectively. The right perirhinal cortex and hippocampus were preferentially involved in successful recognition memory of items devoid of semantic information. In contrast, the left anterior hippocampus was preferentially involved in successful recognition memory of stimuli which contained semantic meaning. These results suggest that the left MTL is preferentially involved in mnemonic processing of verbal/semantic information. In contrast, the right MTL is preferentially involved in visual/non-semantic mnemonic processing. We propose that during development, the left MTL becomes specialised for verbal mnemonic processing due to its proximity with left lateralised cortical language processing areas while visual/non-semantic mnemonic processing gets 'crowded out' to become predominantly, but not completely, the domain of the right MTL. Hum Brain Mapp 37:933-941, 2016. © 2015 Wiley Periodicals, Inc.

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