A recent study published in the journal "Nature Neuroscience" depicted that recurrent and highly focused neuromodulation grounded in the spatiospectral characteristics of memory-specific cortical circuitry can be used to selectively and sustainably exploit the plasticity of the aging brain. An ongoing objective of translational medicine is the creation of technologies that can preserve or improve memory in older adults. This study outlined recurrent transcranial alternating current stimulation (tACS) methods with the purpose of selectively improving long-term memory and working memory in persons aged 65 to 88 over the course of four days.

Investigators examined the modification of theta rhythms in the inferior parietal lobule, often known as the recency effect, to see if it could enhance older individuals' auditory-verbal working memory performance. Furthermore, in what the investigators referred to as "Experiment 1," it was established which modification of dorsolateral prefrontal cortex-nested gamma rhythms would enhance the auditory-verbal long-term memory function known as the primacy effect.

For carrying out neurorhythm modulation experiments, high-definition-tACS were used in conjunction with suitable source-sink setups of nine 12 mm ring electrodes (8 x 1, tACS). The authors also looked at if neuromodulation would be more advantageous for older persons with poorer general cognitive function. Experiment 2's aim was to substantiate the specificity of Experiment 1's frequency and location. In order to do this, the entrainment frequencies were altered in two areas.

Comparable to Experiment 1, Experiment 3 assessed the impact of gamma modulation in the  dorsolateral prefrontal cortex and theta modulation in the inferior parietal lobule on a different group of volunteers. Across all 3 experiments, the goal of the research was to recognize dissociable dual-memory stores on the basis of the distinctive spatiospectral functional and anatomical characteristics of their substrates.

On days 3 and 4 and one month post-treatment, modulating synchronous low-frequency but not high-frequency effect in parietal cortex preferentially boosted working memory. Contrarily, modulating synchronous high-frequency but not low-frequency effect in prefrontal cortex particularly enhanced long-term memory on second and fourth days and one month post-treatment. The amount of memory benefits one month later was predicted by the rate of memory enhancement over four days. People with lower cognitive ability at baseline reported greater, longer-lasting memory gains. Thus, a four-day tACS is beneficial to boost memory function in older people.