SemAD

Human memory, especially semantic memory, plays a key role in storing and accessing knowledge, including language and concepts. This unique memory enables humans to conduct daily communication. Research shows that both aging and neurodegenerative conditions like Alzheimer's Disease (AD) can impact semantic memory, leading to deficits in various language related daily tasks.

In clinical settings, Category Verbal Fluency Test (CVFT) often is used to test the dysfunction of semantic memory. This test requires individuals to list words from a given category, relying on both vocabulary retrieval and semantic memory. Studies have shown that aging and conditions like AD lead to a specific decline in CVFT performance, highlighting semantic memory disruptions. However, the simple word count data from CVFTs cannot pinpoint specific cognitive deficits.

At the neural level, disruptions in semantic memory may be linked to changes in the cognitive map, with grid cells in the entorhinal cortex playing a key role in organizing both spatial and abstract concepts. Grid cell dysfunction, often seen in early AD, is thought to contribute to declines in semantic processing and tasks like CVFT.

Background and aims

A key early sign of Alzheimer's Disease (AD) is a decline in language function, especially in how we process meanings of words and concepts. This impairment causes distorted mental representations, where unrelated ideas become incorrectly connected. Research shows that older adults experience a decline in their ability to perform well on tests of word meaning.

This decline in semantic memory is linked to changes in brain regions, particularly the entorhinal cortex, which plays a critical role in how we process concepts. Early signs of AD affect this brain area, where specialized cells, called grid cells, are located. These cells help organize and make sense of abstract ideas. However, we are still lack of direct evidence to link the disruptions in their function with language difficulties seen in both AD and aging.

This study will explore how grid cells help us process the meaning of words and concepts, starting with young adults. It will also look at how these brain functions change with age and how they relate to performance on word-meaning tests in older adults. The goal is to better understand how aging affects the brain's ability to process meaning and identify potential early signs of cognitive decline.

Overview

This study is designed to explore the neural mechanisms underlying semantic processing, with a specific focus on how grid-like activity in the entorhinal cortex contributes to semantic representation. Functional magnetic resonance imaging (fMRI) will be employed alongside behavioral assessments to investigate the link between neural activity and language task performance.

Participants will include both aging and young groups, and data will be collected during word comparison task, word placement task and verbal fluency task. The study will incorporate advanced data analysis techniques to uncover meaningful patterns in both neural and behavioral data.

Course of the study

The study includes recruitment and baseline assessments, fMRI scanning sessions, and follow-up data collection as needed. Neuroimaging and behavioral data analysis will commence after data collection.

Principal investigator: Prof. Dr. Thomas Wolbers
Start of the study: Q4/2024
Status: monocentric (DZNE Magdeburg), recruiting aktiv

Jiayu Chen
Jiayu.Chen(at)dzne.de