A team from the MRC Cognition and Brain Science Unit and Department of Clinical Neurosciences at the University of Cambridge have demonstrated that the ‘multiple demand’ network for general intelligence is responsible for co-ordinating the response of sensory brain regions when the environment changes. This represents a decade-long effort led by Dr Thomas Cope and Dr Laura Hughes with the co-operation of research teams led by Prof James Rowe, Prof John Duncan and Dr Alexandra Woolgar.
The team measured the brainwaves of 75 patients with different types of dementia, while they listened to sound patterns that changed unpredictably. They compared their brain responses to 48 age-matched healthy individuals and showed that damage to any ‘multiple demand’ region in frontal or parietal lobe reduced the brain’s ability to react to change. There was no such effect from damage to other brain regions, such as those that control memory and language.
The team went on to look at the ways in which brain regions were interacting with each other, and showed that undamaged brain regions were working harder to try and compensate for damage elsewhere. This compensation was only partially effective.
These results are important because they explain why people with different neurodegenerative diseases, which seem to affect unrelated brain regions, all share a difficulty in responding appropriately when the environment changes unexpectedly.
The same mechanisms are likely to underpin other conditions driven by brain network dysfunction, such as schizophrenia. They are also important for our understanding of how the healthy brain works. They show us that ‘multiple demand’ regions for general intelligence are also fundamental for basic perceptual functions that don’t require attention and active thought. Finally, the results validate some animal models of Alzheimer’s disease and Frontotemporal dementia by showing that brain connectivity is abnormal at the same oscillation frequencies in mice and humans.
Cope, TE at al. Causal Evidence for the Multiple Demand Network in Change Detection: Auditory Mismatch Magnetoencephalography across Focal Neurodegenerative Diseases. JNeuro; 8 March 2022; DOI: 10.1523/JNEUROSCI.1622-21.2022
University of Cambridge: Dementia patients struggle to cope with change because of damage to general intelligence brain