Dorothea HämmererUniversity of Innsbruck | UIBK · Developmental Psychology
Dorothea Hämmerer
PhD (Dr. rer. nat.)
About
52
Publications
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Citations since 2017
Introduction
I am interested in understanding how age differences across the lifespan in cognitive and attentional control are related to differences in neuromodulation.
A current focus lies on understanding the cognitive and physiological impact of changes in the noradrenergic system, which appears to be particularly vulnerable in ageing and dementia.
I make use of EEG, (f)MRI, PET and pupillometry as well as pharmacological and non-invasive stimulation interventions.
Additional affiliations
February 2014 - present
October 2012 - February 2014
October 2009 - September 2012
Publications
Publications (52)
The neuromodulatory subcortical system (NSS) nuclei are critical hubs for survival, hedonic tone, and homeostasis. Tau‐associated NSS degeneration occurs early in Alzheimer's disease (AD) pathogenesis, long before the emergence of pathognomonic memory dysfunction and cortical lesions. Accumulating evidence supports the role of NSS dysfunction and d...
The substantia nigra/ventral tegmental area (SN/VTA), the brain’s most prominent dopamine source, is involved in novelty exploration and episodic memory. Using a novelty detection task combined with neuromelanin‐sensitive MRI, this work aimed to investigate the relationship between SN integrity, neural novelty response and subsequent recognition me...
The locus coeruleus (LC) in the brainstem as the main regulator of brain noradrenaline gains increasing attention because of its involvement in neurologic and psychiatric diseases and its relevance in general to brain function. In this study, we created a structural connectome of the LC nerve fibers based on in vivo MRI tractography to gain an unde...
Alterations to the noradrenergic system may occur in the early stages of Alzheimer’s disease (AD) and Parkinson’s disease (PD) and could contribute to clinical symptoms. The aim of this study was to conduct a meta‐analysis of noradrenergic differences in AD and PD assessed using cerebrospinal fluid (CSF) and positron emission tomography (PET) measu...
The noradrenergic locus coeruleus (LC) in the brainstem shows earliest signs of protein pathologies in neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. Its small size (about 3‐4mm in width and 15 mm in length) makes it less suitable for Positron Emission Tomography (PET) investigations, so the past decade has seen a steep ris...
Background:
The Locus Coeruleus (LC) may play an important role in the pathogenesis of Alzheimer's disease (AD). Neuromelanin-sensitive Magnetic Resonance Imaging (MRI) permits the visualization of the LC in vivo. Previously, we proposed an automatic, deep learning-based approach to segmenting the LC in a cohort of 82 healthy young and older adult...
The noradrenergic system shows pathological modifications in aging and neurodegenerative diseases and is thought to be affected in the early stages of both Alzheimer and Parkinson's diseases. We conducted a meta-analysis of noradrenergic differences in Alzheimer's disease type dementia (ADD) and Parkinson's disease (PD) using CSF and PET biomarkers...
The noradrenergic locus coeruleus (LC) in the brainstem shows early signs of protein pathologies in neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. As the LC’s small size (approximately 2.5 mm in width) presents a challenge for molecular imaging, the past decade has seen a steep rise in structural and functional Magnetic Res...
Transcutaneous auricular vagus nerve stimulation (taVNS), as a non-invasive brain stimulation technique may influence the locus coeruleus-norepinephrine system (LC-NE system) via modulation of the Vagus Nerve (VN) which projects to the LC. Few human studies exist examining the effects of taVNS on the LC-NE system and studies to date assessing the a...
Sensitive and reliable in vivo imaging of the locus coeruleus (LC) is important to develop and evaluate its potential as a biomarker in neurodegenerative diseases such as Alzheimer’s disease (AD). It is not known whether AD-related alterations in LC integrity can be detected using ¹⁸F-labelled fluoro-2-deoxyglucose (FDG) positron emission tomograph...
The locus coeruleus‐norepinephrine system (LC‐NE system) supports the process of encoding of emotionally salient events. LC integrity varies in healthy elderly and is associated with altered cognitive functions in aging. Post‐mortem as well as structural indicators suggest that the modulation of the LC‐NE system is reduced in elderly. This reductio...
Postmortem studies show that the locus coeruleus (LC), the major source of cortical noradrenergic projections, exhibits evidence of neurodegeneration early in Alzheimer’s disease (AD). Indeed, the noradrenergic system is more affected than the dopaminergic or cholinergic ones. Albeit to a smaller extent, neuronal loss in the LC is also seen in cogn...
Given its non-invasive nature, there is increasing interest in the use of transcutaneous vagus nerve stimulation (tVNS) across basic, translational and clinical research. Contemporaneously, tVNS can be achieved by stimulating either the auricular branch or the cervical bundle of the vagus nerve, referred to as transcutaneous auricular vagus nerve s...
The locus coeruleus (LC), the origin of noradrenergic modulation of cognitive and behavioral function, may play an important role healthy ageing and in neurodegenerative conditions. We investigated the functional significance of age-related differences in mean normalized LC signal intensity values (LC-CR) in magnetization-transfer (MT) images from...
The error-related negativity (ERN/Ne) as well as the early and late error positivity (Pe) are electrophysiological correlates known to reflect error detection and error awareness. Despite much evidence on age differences in mastering response conflicts, the development and the functional distinctiveness of these components across the lifespan is st...
Pathological alterations to the locus coeruleus, the major source of noradrenaline in the brain, are histologically evident in early stages of neurodegenerative diseases. Novel MRI approaches now provide an opportunity to quantify structural features of the locus coeruleus in vivo during disease progression. In combination with neuropathological bi...
Aging and dopamine modulation have both been independently shown to influence the functional connectivity of brain networks during rest. Dopamine modulation is known to decline during the course of aging. Previous evidence also shows that the dopamine transporter gene (DAT1) influences the re-uptake of dopamine and the anyA9 genotype of this gene i...
Determining the best model or models for a particular data set, a process known as Bayesian model comparison, is a critical part of probabilistic inference. Typically, this process assumes a fixed model-space (that is, a fixed set of candidate models). However, it is also possible to perform Bayesian inference over model-spaces themselves, thus det...
Older adults struggle in dealing with changeable and uncertain environments across several cognitive domains. This has been attributed to difficulties in forming adequate task representations that help navigate uncertain environments. Here, we investigate how, in older adults, inadequate task representations impact on model-based reversal learning....
The locus coeruleus (LC), the major origin of noradrenergic modulation of the central nervous system, may play an important role in neuropsychiatric disorders including Parkinson's disease and Alzheimer's disease. The pattern of age-related change of the LC across the life span is unclear. We obtained normalized, mean LC signal intensity values, th...
A commentary on: Locus Coeruleus Ablation Exacerbates Cognitive Deficits, Neuropathology, and Lethality in P301S Tau Transgenic Mice by Chalermpalanupap, T., Schroeder, J. P., Rorabaugh, J. M., Liles, L. C., Lah, J. J., Levey, A. I., et al. (2018). J. Neurosci. 38, 74–92. doi: 10.1523/JNEUROSCI.1483-17.2017. Alzheimer's disease (AD) is characterize...
Significance
Locus coeruleus (LC) integrity in cognitively normal older adults is a potentially important preclinical marker in dementia. Our study establishes a link between variability in LC integrity and cognitive decline related to noradrenergic modulation in old age. We find that in older adults, reduced LC integrity explains lower memory perf...
The locus coeruleus (LC), the major origin of noradrenergic modulation of the central nervous system, innervates extensive areas throughout the brain and is implicated in a variety of autonomic and cognitive functions. Alterations in the LC-noradrenergic system have been associated with healthy ageing and neuropsychiatric disorders including Parkin...
A better memory for negative emotional events is often attributed to a conjoint impact of increased arousal and noradrenergic modulation. A decline in noradrenergic modulation (NA) during ageing is well documented but its impact on memory function during ageing is unclear. Using pupil diameter (PD) as a proxy for noradrenergic modulation, we examin...
Author summary
When studying human cognition, it is often assumed that agents form and update beliefs only about the current state of the world, an approach known as Bayesian filtering. However, in many situations there are advantages to making inferences about the most likely sequence of states that have occurred, which involves simultaneously upd...
Post hoc analysis of structural data and age-related differences in structural inference.
Tables giving preliminary model comparison and VBM results. Figures illustrating the effects of ΔLL and L on model fitting.
(DOCX)
During value-based decision making, ventromedial prefrontal cortex (vmPFC) is thought to support choices by tracking the expected gain from different outcomes via a competition-based process. Using a computational neurostimulation approach we asked how perturbing this region might alter this competition and resulting value decisions. We simulated a...
The human midbrain and pons contain nuclei of major neurotransmitter systems that send long-range projections to regulate brain activity in cortical and subcortical structures. Despite being small structures, these nuclei are critically implicated in a very wide range of cognitive and bodily functions, and their dysfunction plays an important role...
Appropriate orientation towards potentially salient novel environmental stimuli requires a system capable of detecting change in the sensorium. Mismatch negativity (MMN), an evoked potential calculated by subtracting the response to a standard repeated stimulus and a rare "odd ball" stimulus, is proposed as such a change detection mechanism. It is...
To evaluate the influence of frontal transcranial direct current stimulation (tDCS) on auditory mismatch negativity (MMN).
MMN is an event related potential calculated by subtracting the amplitude of the evoked potentials in response to a "standard" stimulus from the evoked potentials produced by a rare "oddball" stimulus. Here we assessed the infl...
Maximizing gains during probabilistic reinforcement learning requires the updating of choice - outcome expectations at the time when the feedback about a specific choice or action is given. Extant theories and evidence suggest that dopaminergic modulation plays a crucial role in reinforcement learning and the updating of choice - outcome expectatio...
Maximizing gains during probabilistic reinforcement learning requires the updating of choice – outcome expectations at the time when the feedback about a specific choice or action is given. Extant theories and evidence suggest that dopaminergic modulation plays a crucial role in reinforcement learning and the updating of choice – outcome expec- tat...
The reliability, stability, and signal-to-noise ratio (SNR) of event-related potentials (ERPs) were investigated in children, adolescents, younger adults, and older adults in performance monitoring tasks. P2, N2, P3, and P2-N2 peak-to-peak amplitude showed high odd-even split reliabilities in all age groups, ranging from.70 to.90. Multigroup analys...
In many instances, children and older adults show similar difficulties in reward-based learning and outcome monitoring. These impairments are most pronounced in situations in which reward is uncertain (e.g., probabilistic reward schedules) and if outcome information is ambiguous (e.g., the relative value of outcomes has to be learned). Furthermore,...
In this paper, we review the current literature to highlight relations between age-associated declines in dopaminergic and serotonergic neuromodulation and adult age differences in adaptive goal-directed behavior. Specifically, we focus on evidence suggesting that deficits in neuromodulation contribute to older adults' behavioral disadvantages in l...
By recording the feedback-related negativity (FRN) in response to gains and losses, we investigated the contribution of outcome monitoring mechanisms to age-associated differences in probabilistic reinforcement learning. Specifically, we assessed the difference of the monitoring reactions to gains and losses to investigate the monitoring of outcome...
We recorded Electroencephalograms (EEGs) during a cued Continuous Performance Task (CPT) to investigate lifespan differences in the efficiency of response conflict processing under conditions that put high demands on the ability to suppress a prepotent response. Previous evidence indicates that children and adolescents commit more errors under such...
Age gradient of the mechanism of stimulus-response conflict cost was investigated in a population-based representative sample of 291 individuals, covering the age range from 6 to 89 years. Stimulus-response conflict cost, indicated by the amount of additional processing time required when there is a conflict between stimulus and response options, f...
The IRES-Questionnaire (Indicators of the Rehabilitation Status) is one of the most frequently used assessment tools in medical rehabilitation in Germany. By means of Item-Response-Theory we developed the short form IRES-24 from the long version containing 144 items. The IRES-24 contains four scales: ‘Subjective health’, ‘Functionality in every day...
The IRES-Questionnaire (Indicators of the Rehabilitation Status) is one of the most frequently used assessment tools in medical rehabilitation in Germany. By means of item response theory, we developed the short form IRES-24 from the long version containing 144 items. The IRES-24 contains four scales: "Subjective health", "Functionality in every da...
Projects
Project (1)
The noradrenergic locus coeruleus in the brain stem is among the first brain structures to show pathological changes in dementia. It also shrinks substantially during healthy aging.
I investigate whether a deficit in noradrenergic modulation contributes to memory problems, agitation and difficulties in decision making in healthy aging and early dementia.
