Brain Function: Cortical Excitability and Steady Potentials, Relations of Basic Research to Space Biology

AbstractTranscranial magnetic stimulation (TMS)-evoked potentials (TEPs) allow one to assess cortical excitability and effective connectivity in clinical and basic research. However, obtaining clean TEPs is challenging due to the various TMS-related artifacts that contaminate the electroencephalographic (EEG) signal when the TMS pulse is delivered. Different preprocessing approaches have been employed to remove the artifacts, but the degree of artifact reduction or signal distortion introduced in this phase of analysis is still unknown. Knowing and controlling this potential source of uncertainty will increase the inter-rater reliability of TEPs and improve the comparability between TMS–EEG studies. The goal of this study was to assess the variability in TEP waveforms due to of the use of different preprocessing pipelines. To accomplish this aim, we preprocessed the same TMS–EEG data with four different pipelines and compared the results. The dataset was obtained from 16 subjects in two identical recording sessions, each session consisting of both left dorsolateral prefrontal cortex and left inferior parietal lobule stimulation at 100% of the resting motor threshold. Considerable differences in TEP amplitudes were found between the preprocessing pipelines. Topographies of TEPs from the different pipelines were all highly correlated (ρ>0.8) at latencies over 100 ms. By contrast, waveforms at latencies under 100 ms showed a variable level of correlation, with ρ ranging between 0.2 and 0.9. Moreover, the test–retest reliability of TEPs depended on the preprocessing pipeline. Taken together, these results take us to suggest that the choice of the preprocessing approach has a marked impact on the final TEP, and that caution should be taken when comparing TMS–EEG studies that used different approaches. Finally, we propose strategies to control this source of variability.

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Studying restoration of brain function with fetal tissue grafts: Optimal models

Behavioral and Brain Sciences ◽

10.1017/s0140525x0003750x ◽

1995 ◽

Vol 18 (1) ◽

pp. 70-70

Author(s):

Rae Silver ◽

Joseph LeSauter

Keyword(s):

Suprachiasmatic Nucleus ◽

Brain Function ◽

Reproductive Function ◽

Basic Research ◽

Fetal Tissue ◽

Circadian Rhythmicity ◽

Model Systems ◽

Functional Studies ◽

Tissue Grafts

AbstractWe concur that basic research on the use of CNS grafts is needed. Two important model systems for functional studies of grafts are ignored by Stein & Glasier. In the first, reproductive function is restored in hypogonadal mice by transplantation of GnRH-synthesizing neurons. In the second, circadian rhythmicity is restored by transplantation of the suprachiasmatic nucleus.

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Space Biology Group: Basic Research, Biotechnology, Tissue Engineering, and Instrument Development

CHIMIA International Journal for Chemistry ◽

10.2533/000942903777679145 ◽

2003 ◽

Vol 57 (6) ◽

pp. 321-324 ◽

Cited By ~ 2

Author(s):

Isabelle Walther ◽

Augusto Cogoli

Keyword(s):

Tissue Engineering ◽

Instrument Development ◽

Basic Research ◽

Space Biology ◽

Biology Group

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Non-invasive brain stimulation in childhood epilepsy

Journal of the International Child Neurology Association ◽

10.17724/jicna.2016.113 ◽

2016 ◽

Author(s):

Soumya Ghosh ◽

Lakshmi Nagarajan

Keyword(s):

Brain Function ◽

Magnetic Stimulation ◽

Cortical Excitability ◽

Treatment Resistant ◽

Non Invasive ◽

Normal Humans ◽

Generalized Epilepsy ◽

Patients With Epilepsy ◽

The Brain

Transcranial Magnetic Stimulation (TMS) and Transcranial Direct Current Stimulation (tDCS) are new neurophysiological techniques that allow neurologists and neuroscientists to investigate brain function and neural networks in normal humans as well as in those with neurological and neuropsychiatric disorders.In epilepsy, these techniques reveal abnormal excitability of the brain in focal and generalized epilepsy. Different patterns of excitatory and inhibitory changes detected by TMS have the potential to be used in the clinic for evaluating patients with epilepsy and to help with diagnosis, monitoring and treatment.Repetitive TMS (rTMS) and tDCS have the ability to modulate cortical excitability over prolonged periods and are being trialled for the treatment of epilepsy. However, further studies are needed to find optimal stimulation paradigms that reliably reduce seizures, and to confirm long term benefits and safety of these interventions.There are fewer TMS and tDCS studies in children and it's not clear if patterns of excitability changes are similar to those seen in adults or if there are unique patterns in childhood epilepsies. Continuing interventional trials assessing safety and efficacy of TMS and tDCS offer hope to children with treatment resistant epilepsies.

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