Abstract
The STN is a target for ‘deep brain’ stimulation (DBS) in the treatment of Parkinson's disease. DBS effects are likely to be a mixture of multiple effects, affecting both axons and somata within the STN. We here report on experiments studying one key component of the overall response to DBS, i.e., the effect of stimulation on the activity of neurons within the STN. Two monkeys received two chronic recording chambers each. The two chambers were directed at the same STN. One of them was used to carry out electrical stimulation of the STN with a microelectrode (using monophasic stimulation at 1/s, pulse width 50 µs, amplitude ∼ 300 µA), and the other to simultaneously record the neuronal activity in STN with standard extracellular single-unit recording techniques. Peristimulus histograms were calculated to determine the latency and duration of stimulation-evoked responses. In most cases, STN neurons responded to the nearby stimulation with a cessation of activity, typically starting immediately after the stimulation and lasting for 37.2 ± 20.7 ms (n = 161). In some neurons, the inhibition was followed by an excitation. The results suggest that electrical stimulation of the STN has prominent and complex effects on the neuronal activity within the STN. Given the high frequency of therapeutic DBS (130 Hz), it is unlikely that the excitatory effects will manifest themselves. The inhibitory responses may result from activation of GPe axons which then would inhibit STN neurons. [J Physiol Sci. 2006;56 Suppl:S192]
