Transcranial magnetic stimulation (TMS) is a technology that temporarily activates – or inactivates – parts of the brain using magnetic stimulation. Its ability to selectively turn areas of the brain on or off allows the functions and interconnections of the brain to by studied in a noninvasive and painless manner. Now researchers have shown that the technology can be used to enable rats to learn more easily. While smarter rats probably aren’t high on anyone’s wish list, the technology shows potential for allowing TMS to better treat a variety of brain disorders and diseases in humans, such as severe depression and schizophrenia.
Although repetitive TMS has been used as a diagnostic tool since the mid-1990’s, it has been unclear how the technology influenced the activity of certain brain nerve cells. The researchers from Germany’s Ruhr University Bochum have now shown that various stimulus patterns using TMS changed the activity of distinct neuronal cell types and that certain stimulus patterns led to rats learning more easily.
For the first time, the researchers have shown that TMS’s artificial stimulation of the cortex changes the activity of certain inhibitory nerve cells depending on whether the stimulation patterns are provided continuously (cTMS), or with interruptions (iTMS). They found that when rats were treated with iTBS before training, they learned more quickly than those that were treated with cTMS or those that received no TMS treatment.
“The iTBS treatment therefore initially reduces the activity of certain inhibiting nerve cells more generally, with the result that the following learning activities can be stored more easily," concludes Prof. Funke who led the study. "This process is termed 'gating'."
Repetitive TMS is already being used in clinical trials with limited success for therapy of functional disorders of the brain, most notably severe depression. It has also been shown that inhibitory nerve cells play an important role in neuropsychiatric diseases such as schizophrenia so Prof. Funke hopes his group's findings may lead to more effective treatments in these areas.
"It is doubtless too early to derive new forms of treatment of functional disorders of the brain from the results of our study, but the knowledge obtained provides an important contribution for a possibly more specific application of TMS in future," says Prof. Funke.