Learning increased with brain stimulation

Cerebral stimulation may be used to treat functional disorders of the brain thanks to research which shows stimulating parts of the brain can help rats learn more easily.

Professor Klaus Funke from Rhur-University Bochum has shown that various stimulus patterns created using transcranial magnetic stimulation (TMS) can change the activity of distinct neuronal types.

TMS stimulates the cortex using a magnetic field – in general, brain activity drops as a result of low frequency stimulation, and increases with higher frequencies. The research looked at the effects of theta burst stimulation (TBS) in which 50Hz bursts are interspersed with 5Hz.

“This rhythm is based on the natural theta rhythm of four to seven Hertz which can be observed in an EEG,” Funke said.

The TBS effect is dependent on whether the stimulus patterns are provided continuously – cTBs, an attenuating effect – or with interruptions, iTBS, which had a strengthening effect.

How precisely the activity of nerve cells is changed by repeated stimulation is unknown, but it is assumed synapses between cells are strengthened or weakened, a process which is also important in learning. Funke showed that artificial cortex stimulation changes the activity of certain inhibitory nerve cells as a function of the stimulus pattern used. Nerve cells specialised in inhibition of other nerve cells show a greater variety in shape and activity than their excitatory counterparts.
In a second study, rats treated with iTBS before a training session learned more over those treated with the cTBS.

“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,” Funke said.