Non-invasive brain stimulation therapies

Noninvasive brain stimulation therapies are a promising field for the development of new protocols for the treatment of neuropsychiatric disorders. They are based on the stimulation of neural networks with the intent of modeling their synaptic activity to adequate levels. For this, it is necessary to precisely determine which networks are related to which brain functions, and the normal activation level of each of these networks, so that it is possible to direct the stimulation to the affected networks in order to induce the desired effects. These relationships are under intense investigation by the scientific community, and will contribute to the advancement of treatments by neurostimulation, with the emergence of increasingly accurate and effective protocols for different disorders. Currently, the most used techniques are Transcranial Direct Current Stimulation and Transcranial Magnetic Stimulation, with the most common applications being for treating Major Depressive Disorder. The advancement of research in this field may determine new target networks for stimulation in the treatment of other disorders, extending the application of these techniques and also our knowledge about brain functioning.

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Transcranial magnetic stimulation reveals diminished homoeostatic metaplasticity in cognitively impaired adults

Brain Communications ◽

10.1093/braincomms/fcaa203 ◽

2020 ◽

Vol 2 (2) ◽

Author(s):

Mark H Sundman ◽

Koeun Lim ◽

Viet Ton That ◽

Jack-Morgan Mizell ◽

Chidi Ugonna ◽

...

Keyword(s):

Older Adults ◽

Cognitive Impairment ◽

Transcranial Magnetic Stimulation ◽

Brain Stimulation ◽

Magnetic Stimulation ◽

Cognitive Status ◽

Synaptic Activity ◽

Cognitively Impaired ◽

Non Invasive ◽

Potential Value

Abstract Homoeostatic metaplasticity is a neuroprotective physiological feature that counterbalances Hebbian forms of plasticity to prevent network destabilization and hyperexcitability. Recent animal models highlight dysfunctional homoeostatic metaplasticity in the pathogenesis of Alzheimer’s disease. However, the association between homoeostatic metaplasticity and cognitive status has not been systematically characterized in either demented or non-demented human populations, and the potential value of homoeostatic metaplasticity as an early biomarker of cognitive impairment has not been explored in humans. Here, we report that, through pre-conditioning the synaptic activity prior to non-invasive brain stimulation, the association between homoeostatic metaplasticity and cognitive status could be established in a population of non-demented human subjects (older adults across cognitive spectrums; all within the non-demented range). All participants (n = 40; age range, 65–74, 47.5% female) underwent a standardized neuropsychological battery, magnetic resonance imaging and a transcranial magnetic stimulation protocol. Specifically, we sampled motor-evoked potentials with an input/output curve immediately before and after repetitive transcranial magnetic stimulation to assess neural plasticity with two experimental paradigms: one with voluntary muscle contraction (i.e. modulated synaptic activity history) to deliberately introduce homoeostatic interference, and one without to serve as a control condition. From comparing neuroplastic responses across these experimental paradigms and across cohorts grouped by cognitive status, we found that (i) homoeostatic metaplasticity is diminished in our cohort of cognitively impaired older adults and (ii) this neuroprotective feature remains intact in cognitively normal participants. This novel finding suggests that (i) future studies should expand their scope beyond just Hebbian forms of plasticity that are traditionally assessed when using non-invasive brain stimulation to investigate cognitive ageing and (ii) the potential value of homoeostatic metaplasticity in serving as a biomarker for cognitive impairment should be further explored.

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Head models of healthy and depressed adults for simulating the effects of non-invasive brain stimulation

F1000Research ◽

10.12688/f1000research.15125.1 ◽

2018 ◽

Vol 7 ◽

pp. 704 ◽

Cited By ~ 1

Author(s):

Nya Mehnwolo Boayue ◽

Gábor Csifcsák ◽

Oula Puonti ◽

Axel Thielscher ◽

Matthias Mittner

Keyword(s):

Electric Fields ◽

Brain Stimulation ◽

Brain Anatomy ◽

Imaging Data ◽

Magnetic Resonance Imaging Data ◽

Structural Variations ◽

Major Depressive ◽

Non Invasive ◽

The Past ◽

Dorsolateral Prefrontal

During the past decade, it became clear that the effects of non-invasive brain stimulation (NIBS) techniques such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS) are substantially influenced by variations in individual head and brain anatomy. In addition to structural variations in the healthy, several psychiatric disorders are characterized by anatomical alterations that are likely to further constrain the intracerebral effects of NIBS. Here, we present high-resolution realistic head models derived from structural magnetic resonance imaging data of 19 healthy adults and 19 patients diagnosed with major depressive disorder (MDD). By using a freely available software package for modelling the effects of different NIBS protocols, we show that our head models are well-suited for assessing inter-individual and between-group variability in the magnitude and focality of tDCS-induced electric fields for two protocols targeting the left dorsolateral prefrontal cortex.

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Neuromodulation Special IssueNon-invasive stimulation of the social brain: the methodological challenges

Social Cognitive and Affective Neuroscience ◽

10.1093/scan/nsaa102 ◽

2020 ◽

Author(s):

Tegan Penton ◽

Caroline Catmur ◽

Michael J Banissy ◽

Geoffrey Bird ◽

Vincent Walsh

Keyword(s):

Brain Stimulation ◽

Brain Function ◽

Social Brain ◽

Non Invasive ◽

Social Processing ◽

The Social ◽

Social Difficulties ◽

Lesion Studies ◽

Reliable Interpretation ◽

Stimulation Of

Abstract Use of non-invasive brain stimulation methods (NIBS) has become a common approach to study social processing in addition to behavioural, imaging and lesion studies. However, research using NIBS to investigate social processing faces challenges. Overcoming these is important to allow valid and reliable interpretation of findings in neurotypical cohorts, but also to allow us to tailor NIBS protocols to atypical groups with social difficulties. In this review, we consider the utility of brain stimulation as a technique to study and modulate social processing. We also discuss challenges that face researchers using NIBS to study social processing in neurotypical adults with a view to highlighting potential solutions. Finally, we discuss additional challenges that face researchers using NIBS to study and modulate social processing in atypical groups. These are important to consider given that NIBS protocols are rarely tailored to atypical groups before use. Instead, many rely on protocols designed for neurotypical adults despite differences in brain function that are likely to impact response to NIBS.

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