Enhancing memory performance with rTMS in healthy subjects and individuals with Mild Cognitive Impairment: the role of the right dorsolateral prefrontal cortex

Abstract

A debated question in the literature is the degree of anatomical and functional lateralization of the executive control processes sub-served by the dorsolateral prefrontal cortex (DLPFC) during recognition memory retrieval. We investigated if transient inhibition and excitation of the left and right DLPFC at retrieval by means of repetitive transcranial magnetic stimulation (rTMS) modulate recognition memory performance in 100 healthy controls (HCs) and in eight patients with Mild Cognitive Impairment (MCI). Recognition memory tasks of faces, buildings, and words were used in different experiments. rTMS-inhibition of the right DLPFC enhanced recognition memory in both HCs and MCIs. rTMS-excitation of the same region in HCs deteriorated memory performance. Inhibition of the right DLPFC could modulate the excitability of a network of brain regions, in the ipsilateral as well as in the contralateral hemisphere, enhancing function in HCs or restoring an adaptive equilibrium in MCI.

Effects of repetitive transcranial magnetic stimulation on improvement of cognition in elderly patients with cognitive impairment: a systematic review and meta‐analysis

“…Coppi et al () and Ash et al () reported using the fronto‐parietal–temporal lobes and prefrontal areas, respectively, without specifying the exact target site. Regarding the targeting method, six studies used magnetic resonance imaging‐guided navigation (Cotelli et al , ; Cotelli et al , ; Turriziani et al , ; Rabey et al , ; Anderkova et al , ; Lee et al , ) and three studies used a non‐imaging‐based technique (Ahmed et al , ; Drumond Marra et al , ; Rutherford et al , ), either a 5‐cm rule to locate the DLPFC (Pascual‐Leone et al , ) or an electroencephalography 10–20 system to locate the brain area.…”

Causal Role of Prefrontal Cortex in Strengthening of Episodic Memories through Reconsolidation

“…Second, to determine whether the rTMS effect was topographically specific, we applied rTMS over the vertex after memory reactivation (Vertex-R, control site) [6]. We chose the frequency of rTMS on the basis of a recent study showing that 1 Hz rTMS of right lateral PFC enhanced episodic memory performance when delivered during the interval (10 min) between encoding and retrieval [18]. Memory recall was tested on Day 3 (24h post-reactivation) (see Figure 1 and Supplemental Information).…”

Noninvasive Stimulation of Prefrontal Cortex Strengthens Existing Episodic Memories and Reduces Forgetting in the Elderly

“…However, this principle is mainly derived from basic studies of motor cortex and does not necessarily apply to other cortical regions and more complex cognitive functions (Sandrini et al, 2011). For instance, Turriziani et al (2012) showed that 1 Hz rTMS (considered to have an inhibitory effect) of right DLPFC enhanced episodic memory while intermittent Theta Burst Stimulation (considered to have a facilitatory effect) of the same region deteriorated memory performance. In addition, there is evidence that 1 Hz rTMS may improve performance of a cognitive task by strengthening the connectivity between taskrelevant brain regions depending on the functional state of the cortex at the time of stimulation (Ward et al, 2010).…”