Science Times: Electrical Stimulation of the Mesial Temporal Lobe to Enhance Memory: More Questions than Answers

Loss of memory is a dreaded and increasingly common affliction. In the vast majority of cases, few effective treatment options are available. When Suthana et al1 reported in 2012 that stimulation of the entorhinal cortex improved spatial memory, the news was met with cautious optimism. Deep brain stimulation (DBS) has gained attention as a possible treatment option for a growing number of otherwise refractory neurological conditions, including Alzheimer’s disease. DBS of the fornix demonstrated a promising effect on neuroimaging correlates of improved memory in a Phase I pilot study2 but did not prove beneficial for cognitive outcomes in a larger Phase II trial.3 The search for a DBS target to enhance memory remains ongoing.

The entorhinal and hippocampal regions are known to have a key role in declarative memory and are therefore plausible targets for modulating memory performance. However, direct stimulation of the hippocampus had no effect on memory performance in Suthana et al,1 and previous studies found that it impaired verbal memory.4,5 Building on this inconclusive and at times contradictory body of evidence, Jacobs et al6 set out to clarify the effects of entorhinal and hippocampal stimulation on verbal and spatial memory.

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