Effects of transcranial magnetic stimulation over the dorsolateral prefrontal cortex on cognitive control and on the autonomic nervous system

Autor: Städtgen, Mario
Přispěvatelé: Gauggel, Siegfried
Jazyk: angličtina
Rok vydání: 2008
Předmět:
Zdroj: Aachen : Publikationsserver der RWTH Aachen University 55 S. : graph. Darst. (2008). = Aachen, Techn. Hochsch., Diss., 2008
Popis: With transcranial magnetic stimulation (TMS) it is possible to influence the activity of cortical structures and to investigate the effects on behaviour. In the present thesis the impact of TMS over the prefrontal cortex, particularly the DLPFC, on the inhibition of initiated responses, an important part of cognitive control functions, and on the sympathetic and parasympathetic branches of the autonomic nervous system was investigated. The prefrontal cortex is involved in these functions but the exact role of the left and right DLPFC is still unclear. The aim of Study 1 was the investigation of the role of the DLPFC for the inhibition of initiated responses, an important part of cognitive control. Single-pulse TMS was applied over the left, right or bilateral DLPFC at different time points following the stop signal in a stop signal inhibition task to elucidate the functional role of the DLPFC during response abortion and to understand the time course of its involvement. An acceleration of inhibition of initiated responses was observed in all TMS conditions compared to the control condition without TMS. The effect was significantly more pronounced during stimulation over the right DLPFC 50 ms and 100 ms after the stop signal. Right DLPFC seems to be more involved in inhibition of initiated responses than the left DLPFC. The aim of the second study was the investigation of the influence of low-frequency (1 Hz) repetitive TMS (rTMS) over the DLPFC on the control and regulation of ANS activity, particularly cardiovascular activity. MRI guided rTMS was applied to the left and right DLPFC, and a control site (vertex), respectively. ECG was recorded during and after rTMS stimulation. Spectral parameters of HRV were extracted as indicators of the sympathetic and parasympathetic activity of the ANS. Thus it was possible to study the impact of prefrontal rTMS on the cortical control of the sympathetic and parasympathetic branches of the ANS separately. The main finding of the experiment was a differential neuromodulatory effect of low-frequency rTMS applied to the left and right DLPFC on HRV as an indicator of ANS activity. Left-sided stimulation increased parasympathetic activity and attenuated the sympathetic branch of the human ANS. To the contrary, rTMS applied to the right prefrontal cortex enhanced sympathetic activity and decreased parasympathetic activity. Thus a dissociation of sympathovagal balance was observed. It was possible to manipulate sympathetic and parasympathetic ANS activity separately by rTMS. Whether the findings of this thesis are of therapeutic or diagnostic use needs to be investigated in further studies. In several diseases accompanied by disorders of inhibition of ongoing responses, e.g. attention deficit hyperactivity disorder (ADHD), Parkinson’s disease or schizophrenia other therapeutic interventions could be supported by TMS over the right DLPFC. Further studies in healthy subjects as well as in patients with neuropsychiatric diseases are also needed to investigate whether the modulatory effects of rTMS can be used therapeutically to correct, for instance, a pathological imbalance of sympathovagal regulation related to psychosomatic and psychopathological states, e.g. cardiac infarction or depression. Thus the results of the present experimental thesis could help to develop clinical interventions to support the cure of several somatic, psychosomatic and mental diseases.
Databáze: OpenAIRE
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