Targeted pulses of magnetic stimulation to specific regions of the brain have been shown to improve episodic memory, according to new research led by a team from the University of Glasgow (Glas.), Scotland. Episodic memories form an integral part of our being, and yet declines as we age or are subject to chronic brain diseases or traumatic brain injuries.

Over several experiments, Professor Simon Hanslmayr and colleagues, from the university, found inhibiting activity over the left dorsolateral prefrontal cortex (DLPFC) of the brain can improve episodic memory performance – by using low frequency repetitive transcranial magnetic stimulation (rTMS). The researchers hypothesised that they could not only improve memory, but also generate targets for future memory-related therapies in the process.

In the experiments, data was collected from two different cohorts of college students who had been asked to memorise lists of words; half of the students received slow rTMS over the left DLPFC while trying to memorise the words, and the other half received rTMS over a control region of the brain.

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Analysis of the datasets obtained revealed that memory performance was better for words that were memorised while the left prefrontal cortex was being stimulated. Examining the electroencephalogram (EEG) data that was recorded during the experiments, the researchers found that the slow rTMS applied to the prefrontal region in turn led to reduced power of low-frequency (beta) waves in the parietal region of the brain, which is known to be involved in attention and perception.

Mircea van der Plas, Centre for Cognitive Neuroimaging, Glas., said: “Our electrophysiological results suggest that frontal stimulation affects a wider network and improves memory formation by inhibiting parietal areas,” i.e., disinhibited activity of the parietal region leads to enhanced encoding of the words being memorised, and thus improved memory.

van der Plas has suggested further experiments will better explain the “neural basis of memory formation by inhibiting parietal areas.”

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