Multimodal imaging investigation of the brain regions supporting different stages of human memory

We generally take it for granted that we can remember people or objects that we have encountered before, but it is thought that this everyday function of retrieving information from our store of memories may involve a number of separate stages. Which brain areas might be involved in these different stages is a question that has not yet received a satisfactory answer, largely because of limitations in the techniques that have traditionally been used. Recent advances allow us to combine information from different techniques (specifically, functional magnetic resonance imaging or fMRI, and magnetoencephalography or MEG) to identify more precisely where in the brain, and when, different cognitive processes take place. It is proposed to use these techniques in experiments that involve healthy volunteers to determine the networks of brain areas that work together to support the retrieval of information from memory. By observing patterns of brain activity during the different stages of memory retrieval (e.g., processing occurring prior to an attempt to search memory, or the checking of information that has been retrieved from memory), we can improve our understanding of which aspects of memory function are impaired, and which may be spared, in patients with brain dysfunction.

The primary aim of the proposed research is to identify the brain networks that are engaged during the different cognitive processing stages of retrieving information from long-term memory. It is proposed that the operating dynamics of these networks can be established over a millisecond timescale using a multimodal imaging approach that combines functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) with recent advances in analysis of effective connectivity. This proposal will address a key issue in cognitive neuroscience that has remained unresolved because previous studies have limitations that make it difficult to determine which region of the brain is important for which stage of memory retrieval. Combining the multimodal neuroimaging techniques of fMRI and MEG will provide an unprecedented spatial and temporal characterisation of the brain regions such as prefrontal cortex that are involved in different stages of retrieval, including the preparatory processing occurring prior to a retrieval attempt and the post-retrieval monitoring and evaluation of recovered information. Further analyses examining the effective connectivity between brain regions will reveal the functional networks, both within prefrontal cortex and including other areas like the medial temporal lobe and parietal cortex, that enable successful operation of these processes.