Modulation of decision-making by transcranial magnetic stimulation
Date
2019-05-13
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Abstract
Inimese käitumist kontrollivates otsustusprotsessides on oluline roll dorsolateraalsel prefrontaalkorteksil (DLPFK) ning sellega juhteteede kaudu seotud eemalasuvatel ajupiirkondadel, kuid otsustusprotsesside täpsemate neurobioloogiliste mehhanismide kohta on veel vähe teada.
Otsustusprotsesside põhjalik uurimine on oluline nii täidesaatvate funktsioonide ja sihipärase käitumise mõistmiseks kui ka erinevate neuropsühholoogiale tuginevate ravimeetodite väljaarendamiseks.
Käesolev väitekiri keskendus mitte-veridikaalsete otsustusprotsesside uurimisele, kasutades selleks transkraniaalse magnetstimulatsiooni (TMS) meetodit. Otsustusprotsessidega seotud DLPFK piirkondi magnetimpulssidega mõjutades on võimalik tuvastada otsustamise neurobioloogilisi korrelaate ning uurida veridikaalseid ja mitte-veridikaalseid otsusi vastandava teoreetilise mudeli paikapidavust.
Uuring I näitas, et mitte-veridikaalseid otsustusprotsesse on võimalik TMS-i abil selektiivselt mõjutada, kusjuures vasakpoolne DLPFK näib olevat rohkem spetsialiseerunud mitte-veridikaalsetele kognitiivsetele otsustele kui veridikaalsetele, samas kui parempoolne DLPFK osaleb mõlemat tüüpi otsustes. Tulemused ilmestasid ka seda, et TMS rakendamine avaldab korteksi piirkondadele nii lokaalset kui distaalset, TMS lookusest eemalasuvalt realiseeruvat mõju. Uurimuses II leidis kinnitust parempoolse DLPFK oluline roll impulsiivses ja riskantses käitumises: parempoolse DLPFK neurofüsioloogilise erutuvuse pärssimine madalsagedusliku TMS-iga tõi kaasa käitumise pidurduse vähenemise ning oluliselt riskeerivama käitumisstrateegia. Uuring III kinnitas BDNF geeni olulist mõju nii mitte-veridikaalsetele otsustusprotsessidele kui ka sellele, kuidas prefrontaalsete piirkondade mõjutamine TMS-iga mitte-veridikaalset endofenotüübi mõjuga seotud käitumist muudab.
Väitekirja uurimustest järeldub, et TMS meetodil DLPFK piirkondi mõjutades on võimalik otsustusprotsesse mõjutada, kuid vallanduvad käitumuslikud muutused sõltuvad nii ülesande iseloomust, ülesandega seotud kognitiivsete mehhanismide lateralisatsioonist, kui ka inimese neurobioloogilisest endofenotüübist.
Human decision-making is known to depend on the prefrontal cortex and distal areas interconnected to it, but its specific neurobiological mechanisms are still largely unknown. Expanding our knowledge of decision-making processes contributes to understanding the neuropsychological principles of executive function and goal directed behaviour, as well as to advancing the clinical application of neurostimulation in this domain. Within empirical studies included in the current dissertation, repeated transcranial magnetic stimulation (rTMS) was applied to the dorsolateral prefrontal cortex (DLPFC) in order to evaluate potential effects on performance across various decision-making tasks. By observing how non-invasive modulation of neural activity in underlying cortical areas affects non-veridical cognition related behavioural choices, the thesis addressed the functional role of the DLPFC in decision-making processes. Results of Study I demonstrated that non-veridical and veridical decision-making both rely on the right DLPFC, whereas the left DLPFC is more specifically committed to non-veridical cognition. Study I findings also emphasised non-focal, distal effects of TMS, when applied to particularly richly interconnected cortical regions such as the DLPFC. Study II revealed that TMS-induced inhibition of the right DLPFC activity affects non-veridical risky behaviour, suggesting that the right DLPFC plays a role in execution and monitoring of performance in risky tasks with a motor response. Study III revealed that non-veridical behaviour is influenced by genetic differences related to the BDNF gene and that TMS stimulation enhances pre-existing genetically determined biases in decision-making preferences. In conclusion, decision-making behaviour can be modulated by applying TMS to the DLPFC, but the resulting behavioural effects depend on the characteristics of the task, the lateralization of task-specific cognitive mechanisms, as well as the neurobiological endophenotypes involved.
Human decision-making is known to depend on the prefrontal cortex and distal areas interconnected to it, but its specific neurobiological mechanisms are still largely unknown. Expanding our knowledge of decision-making processes contributes to understanding the neuropsychological principles of executive function and goal directed behaviour, as well as to advancing the clinical application of neurostimulation in this domain. Within empirical studies included in the current dissertation, repeated transcranial magnetic stimulation (rTMS) was applied to the dorsolateral prefrontal cortex (DLPFC) in order to evaluate potential effects on performance across various decision-making tasks. By observing how non-invasive modulation of neural activity in underlying cortical areas affects non-veridical cognition related behavioural choices, the thesis addressed the functional role of the DLPFC in decision-making processes. Results of Study I demonstrated that non-veridical and veridical decision-making both rely on the right DLPFC, whereas the left DLPFC is more specifically committed to non-veridical cognition. Study I findings also emphasised non-focal, distal effects of TMS, when applied to particularly richly interconnected cortical regions such as the DLPFC. Study II revealed that TMS-induced inhibition of the right DLPFC activity affects non-veridical risky behaviour, suggesting that the right DLPFC plays a role in execution and monitoring of performance in risky tasks with a motor response. Study III revealed that non-veridical behaviour is influenced by genetic differences related to the BDNF gene and that TMS stimulation enhances pre-existing genetically determined biases in decision-making preferences. In conclusion, decision-making behaviour can be modulated by applying TMS to the DLPFC, but the resulting behavioural effects depend on the characteristics of the task, the lateralization of task-specific cognitive mechanisms, as well as the neurobiological endophenotypes involved.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone
Keywords
otsustamine, neurobioloogia, transkraniaalne magnetstimulatsioon, otsmikusagar, individuaalne käitumine