The long-held theory that our brains use different mechanisms for forming long-term and short-term memories has been challenged by new research from UCL, published in PNAS.
Neuroscientists formed this theory based on observation of patients with amnesia, a condition that severely disrupts the ability to form long-lasting memories. Typically, amnesia is caused by injury to the hippocampi, a pair of brain structures located in the depth of the temporal lobes.
The team studied patients with a specific form of epilepsy called ‘temporal lobe epilepsy with bilateral hippocampal sclerosis’, which leads to marked dysfunction of the hippocampi. They asked the patients to try and memorise photographic images depicting normal scenes, for example chairs and a table in a living-room. Their memory of the image was tested and brain activity recorded using MEG (magnetoencephalography) after a short interval of just five seconds, or a long interval of 60 minutes.
Nathan Cashdollar, (Department of Clinical and Experimental Epilepsy) first author of the paper, said: “Recent behavioural observations had already begun challenging the classical distinction between long-term and short-term memory which has persisted for nearly half a century. However, this is the first functional and anatomical evidence showing which mechanisms are shared between short-term and long-term memory and which are independent.”
“They also highlight that patients with impaired long-term memory have a short-term memory burden to carry in their daily life as well.”
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Reference >> Cashdollar,N., Malecki,U., Rugg-Gunn,F.J., Duncan,J.S., Lavie,N., Duzel,E. ‘Hippocampus dependent and independent theta-networks of active maintenance’ is published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) Monday 9th November online early edition.