This project aims at understanding the cortical dynamics and brain structural determinants governing the flexible allocation of attentional resources in young and healthy ageing subjects. We focus on processes that (1) allow the dividing of resources for the processing of multiple simultaneous visual features or objects and (2) underlie the plasticity and amplification of attentional resource allocation in the normal ageing cortex as a function of individual cortical myelination. As a general experimental approach, we will use versions of the multiple-object and multiple-feature tracking (MOT, MFT) paradigm, which grant insights into resource allocation processes by pushing parallel attentional selection processes to their limit. Our own previous work has shown that observers differ in their capacity and strategy in performing these tasks. Most importantly, they differ with regard to their potential to optimise and enhance resource allocation strategies via training. This project will focus in particular on the mechanisms behind the variation and learnability of tracking strategies in young and elderly adults. There is common agreement that attention is a time-cycling operation, with limits of parallel resource allocation set by neural processing (cycling) time. The latter is intrinsically related to intracortical myelination, which shows age-related decline even in the healthy ageing population. The specific goal is to clarify the link between time-critical MOT/MFT performance and the degree of cortical myelination with regard to inter-individual differences and age-related changes in normally ageing populations. The temporal dynamics of the involved cortical processes will be investigated using high spatiotemporal resolution EEG and MEG recordings. Cortical myelination and connectivity will be assessed using MR imaging (R1-imaging, DTI). This project will also include a mesoscale level analysis of cortical activity changes (7T fMRI) during attentional tracking of objects and features.

Conceptual framework of the project:

Overview of neural resources (blue and yellow brain areas) and readouts of brain structural/functional measures (myelination, connectivity and electromagnetic activity) to be obtained in younger and older adults. Core questions are (1) whether, and if yes, how MOT/MFT performance variation depends on myelination, connectivity and patterns of electromagnetic activity within and between age groups, (2) Whether MOT/MFT performance increments of due to training are unspecific (dark purple arrow), or associated with structural/functional changes and connectivity in and between areas defining the neural resource (red arrow). (3) Whether training effects and associated structural/functional changes would be comparable among ages.

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