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PhD defence: Katia Soud

Entitled: "Investigation of Dopamine Release in the Dorsal Hippocampus upon Novelty Exploration and Optogenetic Stimulation of the Locus Coeruleus"

Info about event

Time

Friday 5 April 2024,  at 13:00 - 15:00

Location

Aarhus Universitet, Lokale 1231-424 (Lille Anatomisk Auditorium). Wilhelm Meyers Alle 3, 8000 Aarhus C

Organizer

Graduate School of Health

Press release (Danish):
Locus coeruleus's noradrenalin og dopamin frigives samtidig i hippocampus, hvilken driver hukommelsesboost efter nye oplevelser? Hverdagsoplevelser bliver ofte glemt, medmindre de er forbundet med ekstraordinære begivenheder. For eksempel har mange en detaljeret erindring om deres indkøb i supermarkedet, kort efter annonceringen af den første COVID-19 lockdown. Detaljerne omkring denne hverdags aktivitet, forstærkes i vores hukommelse, på grund af de usædvanlige omstændigheder. Forskning, der undersøger dette fænomen, peger på at det noradrenerge system, specifikt locus coeruleus, spiller en central rolle i processen. Locus coeruleus, faciliterer hukommelse gennem en forbindelse med hippocampus. Nylige undersøgelser, der udfordrer vores gængse opfattelse, har antydet muligheden for at locus coeruleus, udover at frigive noradrenalin, også frigiver dopamin. Det rejser spørgsmålet, er det noradrenalin eller dopamin, der er afgørende i denne hukommelsesproces? I mine forsøg har jeg brugt fluorescerende biosensorer til at lave detaljerede målinger af dopamin og noradrenalin niveauer, under aktivering af locus coeruleus. Dette er gjort med optogenetik eller ved at eksponere rotterne for ekstraordinære miljøer. Mine forsøg afslørede simultan frigivelse af både dopamin og noradrenalin. Efterfølgende forsøg, med brug af hippocampale hjernesnit, understregede behovet for forbedrede metoder, til præcist at differentiere i mellem disse to neuromodulatorer. Mine resultater kaster lys over det komplekse samspil mellem neuromodulatorer i hukommelsesprocesser og baner vejen for yderligere undersøgelser indenfor dette forskningsområde.

Press release (English):
The locus coeruleus's norepinephrine and dopamine co-release in the hippocampus, which is the driver of memory boost after novel experiences? Everyday experiences are often forgotten, unless associated with extraordinary events. For instance, ordinary activities like grocery shopping during the initial COVID-19 lockdown became memorable due to the unprecedented circumstances. Scientists have delved into this phenomenon, revealing the pivotal involvement of the noradrenergic nuclei, the locus coeruleus, in memory consolidation. The locus coeruleus, through its connection with the hippocampus, facilitates memory formation. Recent studies, challenging our previous conception, have suggested the possibility of dopamine co-release from the locus coeruleus, posing intriguing questions regarding the primary neuromodulator responsible for novelty enhanced memory persistence. Norepinephrine, or Dopamine? In this study, I employed live monitoring of dopamine and norepinephrine release, via fluorescent biosensors, following external activation of the locus coeruleus using optogenetics, or coupled with exposure to novel environments in transgenic rats. Our in-vivo fiber-photometry investigation unveiled the simultaneous release of both neuromodulators in the hippocampus from the locus coeruleus. Subsequent experiments utilizing hippocampal slices underscored the need for improved techniques to accurately differentiate between these two neuromodulators. My findings shed light on the complex interplay between neuromodulators in memory processes, paving the way for further studies and a better understanding.