Repetitive transcranial magnetic stimulation (rTMS) is widely recognized as an effective and noninvasive neuromodulation for treating depression, and has been applied in a wide range of clinical settings. However, previous studies often reported inconsistent antidepressant effects that may be due to differences in the rTMS protocols such as coil placement. The typical simulation site for rTMS depression protocol is the left dorsolateral prefrontal cortex (DLPFC). Targeting the exact site of the left DLPFC while considering individual brain structure has been challenging due to the non-invasive nature of rTMS. Several researchers have applied various targeting methods to overcome the abovementioned issue. Most of the previous studies have applied the “5-cm rule” or the “international 10-20 system,” which is easily applicable. Recently, researchers started to apply a neuronavigation system that targets the stimulation site based on neuroimaging of each individual. Pros and cons of targeting methods have been discussed in terms of validity and reliability of targeting stimulation sites, differences in treatment responses, as well as considerations of individual characteristics. Therefore, the current review focuses on the targeting methods of stimulation site and the treatment effects of depression in previous studies. For discussion, we divided neuronavigation methods into using fixed coordinates and using individualized targets. Furthermore, the limitations of each targeting method are discussed that may potentially contribute to the development of the optimal rTMS protocol for depression treatment.

Hyperbaric oxygen therapy (HBOT) is a noninvasive method that supplies pure oxygen under a pressure greater than normal atmospheric pressure to increase the partial pressure of oxygen in the plasma and tissue. Based on the potential mechanisms of HBOT, including neuroprotection and neurological recovery, HBOT has been suggested as a promising therapeutic option for neurological and psychiatric disorders. This review specifically focused on the clinical trials applying HBOT for psychiatric disorders published during the recent decade. We critically reviewed the efficacy and safety of HBOT in psychiatric disorders, and cautiously suggested the future directions for further research.

Transcranial direct current stimulation (tDCS) is a non-invasive and effective neuromodulatory technique to modulate cortical activities by applying 1 to 2 milliamps electric current. The use of tDCS to enhance cognitive function such as executive function and memory has attracted much attention in recent years, and a lot of studies have been carried out to identify neural mechanisms underlying cognitive enhancement effects of tDCS. In this review, we discussed the previous neuroimaging studies on applications of tDCS for cognitive enhancement using functional magnetic resonance imaging (fMRI). Previous tDCS studies for neurological or psychiatric conditions and elderly individuals suggested that cognitive enhancement effects of tDCS were associated with normalizing aberrant brain networks and activities related to pathophysiology. Moreover, tDCS-induced cognitive enhancement in healthy individuals was associated with functional changes in brain activations and network connectivity. Furthermore, cognitive enhancement effects of tDCS were varied depending on the neurological structure and functional characteristics between individuals. The current review may provide critical insights into functional activity and connectivity of the brain regarding cognitive enhancement effects of tDCS, which could give direction for further studies on identifying the specific neural mechanisms and clinical strategies of tDCS.

Cognitive enhancement refers to the improvement of cognitive function related to deficits that occurred as part of a certain illness. However, the term cognitive enhancement does not yet have a definitive meaning, and its connotations often vary depending on the research of interest. Recently, research interests are growing towards enhancing human cognition beyond what has traditionally been considered necessary using various brain devices. The phenomenon of exceeding the cognitive abilities of individuals who are already functional has also introduced new terminologies as means to classify between cognitive enhancing procedures that are part of treatment versus simply supplementary. Of the many devices used to attain cognitive enhancement, transcranial magnetic stimulation (TMS) is a unique neurostimulatory device that has demonstrated significant improvements in various cognitive domains including memory and cognitive processing skills. While many studies have supported the safety and efficacy of TMS in treatment, there has yet to be an optimization in parameter for TMS that is catered to a certain target group. The current paper aims to review with perspective the many studies that have used TMS for the purpose of cognitive enhancement and provide further insight on the development of an optimal stimulation parameter. The paper reviews 41 peer-reviewed articles that used TMS for cognitive enhancement, summarizes the findings that were apparent for each distinct parameter, and discusses future directions regarding TMS as an elective tool for healthy individuals while considering some of the ethical perspectives that may be warranted.
Brain ; Cognition ; Humans ; Memory ; Neuropsychological Tests ; Transcranial Magnetic Stimulation