The parts of the brain that are needed to remember words, and how these are affected by a common form of epilepsy, have been identified by a team of neurologists and neurosurgeons at UCL.
The new study, published in Brain Communications, found that shrinkage in the front and side of the brain (prefrontal, temporal and cingulate cortices, and the hippocampus) was linked to difficulty remembering words.
The new discovery highlights how the network that is involved in creating and storing word memories is dispersed throughout the brain.
This is particularly crucial for helping to understand conditions such as epilepsy, in which patients may have difficulty with remembering words. The researchers hope that their findings will help guide neurosurgical treatment for patients with epilepsy by helping surgeons to avoid parts of the brain important for language and memory, that may otherwise be affected, when doing operations.
Corresponding author, Professor John Duncan (UCL Queen Square Institute of Neurology) said: "Being able to remember and recall words is important for day-to-day memory to work well.
"Detailed MRI brain scans are used to find out the causes of epilepsy and can show if any parts of the brain are shrunken. By measuring the parts of the brain that are shrunken and how well a person can remember words, we can work out which parts of the brain are used for making and storing memories.
"In addition, if medication has not stopped seizures occurring, this helps us to guide neurosurgical treatment for a person's epilepsy, to avoid damaging the parts of the brain that are needed for memory to work well."
In the first study of its kind, the researchers examined 84 people with temporal lobe epilepsy (epilepsy arising from the temporal lobe at the sides of the head) and hippocampal sclerosis (a condition in which part of the brain is scarred, and memory is affected) and 43 healthy people.
The patients were divided into those with left-sided and right-sided hippocampal sclerosis.
High-resolution MRI scans were used to measure the size and shape of different parts of the brain, including the cerebral cortex (the outer layer of the brain responsible for thinking, memory, attention, perception, awareness, and language) and specific areas within the hippocampus (the part of the brain that helps with learning, memory, and spatial navigation).
All participants underwent standardised tests to assess their verbal memory. These tests were part of the Adult Memory and Information Processing Battery, which measures how well people can remember and recall words.
The researchers then compared the memory test scores to the sizes of different brain areas, to see if smaller brain parts were linked to worse memory.
They found that smaller sizes in certain brain areas, like the prefrontal, temporal and cingulate cortices, and parts of the hippocampus, were linked to worse memory for words in people with epilepsy arising in their temporal lobes.
These findings are also important for understanding how the brain organises and remembers words.
Lead author, Dr Giorgio Fiore (National Hospital for Neurology and Neurosurgery, UCLH) said: "This research is important as it helps us to understand how memory may fail and may help guide the designing of neurosurgical operations for epilepsy that will not make memory worse."
This work was funded by the Epilepsy Research UK and supported by the National Institute for Health and Care Research University College London Hospitals Biomedical Research Centre (NIHR UCLH BRC).
