Microstimolazione elettrica

Mentre con la Stimolazione Magnetica Transcranica (TMS) si può inibire o stimolare la corteccia cerebrale in modo non invasivo, per le aree sottocorticali è possibile utilizzare microstimolazioni elettriche di durata limitata e reversibili.
Spesso lo si richiede a volontari che devono subire interventi di neurochirurgia, ad esempio, nel caso di pazienti affetti da Parkinson:

“The present study examined the effects of microstimulation in GPi on the activity of neurons close to the stimulation site.“

“The spontaneous activity of nearly all of the cells (22/23) recorded in GPi in three patients was inhibited by microstimulation at currents typically <10 μA (0.15-ms pulses at 5 Hz). The inhibition had a duration of 10–25 ms at threshold.”

[Dostrovsky JO, Levy R, Wu JP, Hutchison WD, Tasker RR, Lozano AM. Microstimulation-induced inhibition of neuronal firing in human globus pallidus. J Neurophysiol. 2000 Jul;84(1):570-4.]

Qui, su 4 pazienti che dovevano subire un intervento di chirurgia stereotassica:

“Dual microelectrode recordings were performed during stereotactic surgery in 4 patients. Well-isolated high-amplitude units were stimulated extracellularly through the recording microelectrode with 0.5-second trains of high frequency (200 Hz) and low current (≤ 5 μA).”

“In the majority (92%) of SNr neurons, this type of stimulation led to a period of inhibition lasting several hundreds of milliseconds following the end of the train.”

“In previous studies they have shown that microstimulation in the internal globus pallidus, which is functionally similar to the SNr, inhibits firing, whereas similar microstimulation in the STN has minimal effect.”

“The aim of the current study was to examine and compare the aftereffects of local high-frequency microstimulation through the recording electrode on the firing of neurons in the subthalamic nucleus (STN) and the substantia nigra pars reticulata (SNr) in patients undergoing surgery for deep brain stimulation.”

[Lafreniere-Roula M, Hutchison WD, Lozano AM, Hodaie M, Dostrovsky JO. Microstimulation-induced inhibition as a tool to aid targeting the ventral border of the subthalamic nucleus. J Neurosurg. 2009 Oct;111(4):724-8. doi: 10.3171/2009.3.JNS09111.]

E ancora:

“To examine the possibility that impaired inhibition and synaptic plasticity within the basal ganglia play a role in dystonia, the present study used a pair of microelectrodes to test paired pulse inhibition in the globus pallidus interna (GPi) and substantia nigra pars reticulata (SNr) of dystonia and PD patients undergoing implantation of deep brain stimulating (DBS) electrodes.”

[Prescott IA, Dostrovsky JO, Moro E, Hodaie M, Lozano AM, Hutchison WD. Reduced paired pulse depression in the basal ganglia of dystonia patients. Neurobiol Dis. 2013 Mar;51:214-21. doi: 10.1016/j.nbd.2012.11.012. Epub 2012 Nov 29.]



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