Publikationen

Hippocampal subfields and their neocortical interactions during autobiographical memory

2025-05-08T11:30:18Z

Hippocampal subfields and their neocortical interactions during autobiographical memory Leelaarporn, Pitshaporn; Dalton, Marshall A.; Stirnberg, Rüdiger; Stöcker, Tony; Spottke, Annika; Schneider, Anja; McCormick, Cornelia Advances in ultra-high field 7 Tesla functional magnetic resonance imaging (7 T fMRI) have provided unprecedented opportunities to gain insights into the neural underpinnings supporting human memory. The hippocampus, a heterogeneous brain structure comprising several subfields, plays a central role during vivid re-experiencing of autobiographical memories (AM). However, due to technical limitations, how hippocampal subfields differentially support AM, whether this contribution is specific to one portion along the hippocampal long-axis, and how subfields are functionally connected with other brain regions typically associated with AM retrieval remains elusive. Here, we leveraged technical advances of parallel imaging and employed a submillimeter Echo Planar Imaging sequence over the whole brain while participants re-experienced vivid, detail-rich AM. We found that all hippocampal subfields along the long-axis were engaged during AM retrieval. Nonetheless, only the pre/parasubiculum within the anterior body of the hippocampus contributed over and above to AM retrieval. Moreover, whole-brain functional connectivity analyses of the same data revealed that this part of the hippocampus was the only one that was strongly connected to other brain regions typically associated with AM, such as the ventromedial prefrontal cortex (vmPFC) and medial/lateral parietal regions. In the context of the broader literature, our results support recent proposals that the anterior body of the pre/ parasubiculum may play an important role in scene-based cognition, such as its engagement during the reexperiencing of personal past events.

Happiness, positive emotions, and subjective well-being in dementia

2025-04-30T15:45:15Z

Happiness, positive emotions, and subjective well-being in dementia Miklitz, Carolin; Fliessbach, Klaus; McCormick, Cornelia Research on non-cognitive features of dementia traditionally focusses on neuropsychiatric symptoms and challenging behavior and thus on negative aspects of the disease. Despite the clinical observation that many patients frequently report subjective well-being and often express positive emotions there is only little research on the definition, measurement and determinants of subjective well-being and happiness in people living with dementia. Furthermore, the few studies there are, examined happiness using retrospective questionnaires and the accounts of relatives or caregivers. However, in dementia, the experiencing self becomes more significant since past and future thinking are fading into the background. Here, we review the relative scarce literature in this field, discuss different psychological constructs and their applicability for dementia research, and suggest methods for measuring the addressed constructs in people with dementia. In particular, we propose methodology to study happiness and positive emotions in the experienced moment of the participants using ecological momentary assessments (EMA). We believe that adequate measures of momentary subjective well-being might become an important outcome parameter in clinical dementia trials beyond the currently used quality of life measures.

Hippocampal- occipital connectivity reflects autobiographical memory deficits in aphantasia

2025-04-25T14:00:15Z

Hippocampal- occipital connectivity reflects autobiographical memory deficits in aphantasia Monzel, Merlin; Leelaarporn, Pitshaporn; Lutz, Teresa; Schultz, Johannes; Brunheim, Sascha; Reuter, Martin; McCormick, Cornelia Aphantasia refers to reduced or absent visual imagery. While most of us can readily recall decade-old personal experiences (autobiographical memories, AM) with vivid mental images, there is a dearth of information about whether the loss of visual imagery in aphantasics affects their AM retrieval. The hippocampus is thought to be a crucial hub in a brain-wide network underlying AM. One important question is whether this network, especially the connectivity of the hippocampus, is altered in aphantasia. In the current study, we tested 14 congenital aphantasics and 16 demographically matched controls in an AM fMRI task to investigate how key brain regions (i.e. hippocampus and visual- perceptual cortices) interact with each other during AM re-experiencing. All participants were interviewed regarding their autobiographical memory to examine their episodic and semantic recall of specific events. Aphantasics reported more difficulties in recalling AM, were less confident about their memories, and described less internal and emotional details than controls. Neurally, aphantasics displayed decreased hippocampal and increased visual-perceptual cortex activation during AM retrieval compared to controls. In addition, controls showed strong negative functional connectivity between the hippocampus and the visual cortex during AM and resting-state functional connectivity between these two brain structures predicted better visualization skills. Our results indicate that visual mental imagery plays an important role in detail-rich vivid AM, and that this type of cognitive function is supported by the functional connection between the hippocampus and the visual-perceptual cortex.

Use of Cerebrospinal Fluid Biomarkers of Alzheimer’s Disease Risk in Mild Cognitive Impairment and Subjective Cognitive Decline in Routine Clinical Care in Germany

2024-07-08T09:33:24Z

Use of Cerebrospinal Fluid Biomarkers of Alzheimer’s Disease Risk in Mild Cognitive Impairment and Subjective Cognitive Decline in Routine Clinical Care in Germany Bartels, Claudia; Kögel, Anna; Schweda, Mark; Wiltfang, Jens; Pentzek, Michael; Schicktanz, Silke; Schneider, Anja Background: The National Institute of Aging and Alzheimer's Association's diagnostic recommendations for preclinical Alzheimer's disease (AD) and mild cognitive impairment (MCI) define AD by pathological processes which can be detected by biomarkers. These criteria were established as part of a research framework intended for research purposes but progressively enter the clinical practice.
Objective: We investigated the availability, frequency of use, interpretation, and therapeutic implications of biomarkers for the etiologic diagnosis and prognosis in MCI and subjective cognitive decline (SCD) in routine clinical care.
Methods: We conducted a cross-sectional questionnaire survey among 215 expert dementia centers (hospitals and memory clinics) in Germany.
Results: From the 98 centers (45.6% of contacted centers) included, two-thirds reported use of the cerebrospinal fluid (CSF) biomarkers Aß42, tau, and phospho-tau in the diagnostic workup of MCI and one third in SCD. CSF biomarker analysis was more often employed by neurological (MCI 84%; SCD 42%) compared to psychiatric institutions (MCI 61%; SCD 33%; p=0.001). Although dementia experts disagreed on the risk of progression associated with different CSF biomarker constellations, CSF biomarker results guided therapeutic decisions: ~40% of responders reported to initiate cholinesterase inhibitor therapy in MCI and 18% in SCD (p = 0.006), given that all CSF biomarkers were in the pathological range.
Conclusion: Considering the vast heterogeneity among dementia expert centers in use of CSF biomarker analysis, interpretation of results, and therapeutic consequences, a standardization of biomarker-based diagnosis practice in pre-dementia stages is needed.