Vloga medialnega prefrontalnega korteksa pri odločanju v negotovih razmerah pri podganah

Mikuš, Nace (avtor), Klausberger, Thomas (mentor), Passecker, Johannes (komentor)

Veliko vedenjskih vzorcev živali in ljudi bi lahko formulirali kot problem agenta, ki se odloča med različnimi možnostmi z različnimi izidi. Ker živimo v zelo kompleksnem okolju, so ti izidi po navadi prežeti z negotovostjo. Zato ni presenetljivo, da se mnogokrat odločamo za možnosti, ki prevedejo do slabih posledic. Ta problem odločanja je poudarjen pri ljudeh z različnimi psihiatričnimi boleznimi, kar vodi do daljšega okrevanja, slabše kvalitete življenja in celo smrti. Psihotropna zdravila igrajo veliko vlogo pri zdravljenju duševnih boleznih, čeprav zelo slabo razumemo kako delujejo. Boljše poznavanje nevralnih mehanizmov za procesi odločanja lahko privede do bolj usmerjenih farmakoloških terapij. Veliko antipsihotikov in antidepresivov temelji na procesih, ki povečujejo ali zmanjšujejo pretok dopamina in serotonina v možganih. Srednje možganska območja, ki distribuirajo dopamin in serotonin po celih možganih, skozi tesne povezave s podkortikalnimi in kortikalnimi možganskimi strukturami tvorijo nevronska vezja, ki so vpletena v širok spekter vedenjskih vzorcev in počutij. Dorsolateralni prefrontalni korteks in anteriorni cingulum sodelujeta v mehanizmu kognitivnega nadzora vedenja in sta zato ključna pri odločanju v negotovih razmerah. Medialni prefrontalni korteks pri podganah velja za funkcijski in anatomski homolog teh območij. V raziskavi smo združili že obstoječe podatke, pridobljene skozi snemanje aktivnosti medialnega prefrontalnega korteksa pri podganah, z vedenjskim modelom, da bi bolje razumeli, kakšna je vloga medialnega prefrontalnega korteksa pri odločanju v spremenljivih razmerah. Snemanje nevralne aktivnosti je potekalo med tem, ko so se podgane odločale med gotovo malo nagrado in negotovo večjo nagrado. Uporabili smo algoritem vzpodbujevalnega učenja in modelirali verjetnost, da bo podgana izbrala eno ali drugo možnost. Poleg tega smo uporabili podatke pridobljene z optogenetično stimulacijo, da smo lahko definirali nevrone, ki iz medialnega prefrontalnega korteksa projecirajo v jedro rafe in v ventralno tegmentalno območje. Našli smo celice, ki korelirajo svojo aktivnost z izbiro, z izidom izbire in z modelirano verjetnostjo. Večina nevronov, ki so projecirali iz medialnega prefrontalnega korteksa v srednje možganska jedra, so korelirali svojo aktivnost z vedenjskimi spremenljivkami, še posebej z spremenljivko verjetnosti. Naši rezultati kažejo na to, da igra medialni prefrontalni korteks pomembno vlogo pri ohranjanju vedenjskih strategij, ki privedejo do največjega dobička na dolgi rok. Podatki kažejo na to, da je ta mehanizem, vsaj deloma, implementiran v projekcijah iz frontalnih delov v dopaminergična in serotoninergična srednje možganska jedra.

• Jezik: Slovenski jezik
• Ključne besede: nevroekonomija
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: PEF - Pedagoška fakulteta
• Leto izida: 2016
• PID: 20.500.12556/RUL-88506
• COBISS.SI-ID: 11414601
• Datum objave v RUL: 31.08.2017

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: The role of the medial prefrontal cortex in uncertainty based decision making in rats

Izvleček

Many behavioural patterns of humans and nonhuman animals could be framed as a problem of an agent deciding between various alternatives that have different outcomes. Since we live in a very complex environment these outcomes are usually soaked in uncertainty and ambiguity. It is therefore not surprising that many of us often make decisions that have bad consequences. Various psychiatric illnesses exacerbate this decision making problem, which leads to longer recovery times, poorer life quality and even death. Psychotropic drugs play a big role in mental disease treatment, but our understanding of why they work remains very superficial. Uncovering precise neural mechanisms underlying decision making processes has the potential to open up new venues for more targeted pharmacological treatments. Most antipsychotic and antidepressant drugs are based on processes that either stimulate or inhibit the flow of dopamine and serotonin. Midbrain areas that supply the brain with dopamine and serotonin are inter-connected to the subcortical and cortical areas of the brain, forming neural circuits that are involved in a wide range of behavioural patterns and moods. The dorsolateral prefrontal cortex and the anterior cingulate cortex contribute to the mechanism of top-down control of behaviour and are crucial in uncertainty based decision tasks. The medial prefrontal cortex in rats has been proposed as their functional and anatomical homologue. We have combined neural data, that was previously recorded from the medial prefrontal cortex in rats, with a behavioural model, to better understand what is the role of the medial prefrontal cortex in dynamic decision making. The data was recorded while the rats were deciding between a smaller immediate reward and a larger probabilistic reward. We used a reinforcement learning algorithm to model the probability of the rat choosing one option or the other. Additionally, we used data acquired from optogenetic stimulations to define neurons that project from the medial prefrontal cortex to the dorsal raphe nucleus and the ventral tegmental area. We found cells that correlate their firing rates with choice, outcome of choice and with the modelled probability of choosing one or the other arm. The majority of the projections cells were task responsive, with most of them correlating their firing rates with the probability variable. Our results indicate that the medial prefrontal cortex in rats contributes to maintaining behavioural strategies that maximize long-term outcomes and suggest that this could be achieved at least party via the frontal projections to the serotonergic and dopaminergic midbrain areas.

• Ključne besede: neuroeconomics