Banca de QUALIFICAÇÃO: JOHSEPH PABALLO GOMES DE SOUZA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOHSEPH PABALLO GOMES DE SOUZA
DATE: 10/10/2025
TIME: 14:00
LOCAL: https://meet.google.com/jry-yccd-pst; Laboratório de pesquisa da memória
TITLE:

THETA–HFO COUPLING IN THE DORSAL HIPPOCAMPUS AS A NEURAL BIOMARKER OF DECISION MAKING UNDER PRESUMED THREAT IN FEAR MEMORY EXTINCTION 

 

KEY WORDS:

Extinction; Hippocampus; Theta-HFO Coupling;

PAGES: 74
BIG AREA: Ciências Biológicas
AREA: Fisiologia
SUMMARY:

Fear memory extinction is the process by which a learned aversive response is reduced through repeated exposure to the fear-associated environment, but without the aversive stimulus. This mechanism is central both for understanding trauma-related disorders and for improving therapeutic strategies. Although structures such as the amygdala, prefrontal cortex, and hippocampus are known to be involved, specific electrophysiological markers of aversive instrumental extinction remain insufficiently characterized. Recently, phase-amplitude coupling (PAC) between theta and high-frequency oscillations (theta–HFO) has emerged as a potential neural marker of these processes. In this study, we evaluated the electrophysiological activity of the dorsal hippocampus in rats during inhibitory avoidance extinction, focusing on theta–HFO coupling. Local field potentials (LFPs) were recorded in the CA1 region of the hippocampus, and PAC was analyzed at different moments of the extinction session, particularly around the moment when the animal stepped down from the safe platform to explore the environment previously associated with the aversive stimulus. Our results revealed a transient and significant increase in theta–HFO modulation index immediately before decision-making, an effect that was absent during pre-exposure and after extinction, indicating specificity for the period in which aversive memory still influences behavior. Moreover, this coupling showed a strong correlation with behavioral avoidance indices, suggesting a predictive role in extinction dynamics. Taken together, these data indicate that theta–HFO coupling in the dorsal hippocampus is a promising neural marker for decision-making under threat during fear memory extinction. These findings fill an important gap in the characterization of the oscillatory mechanisms underlying aversive instrumental extinction and pave the way for future investigations into interventions that can modulate this coupling, with potential translational applications in fear-related disorders.

 

COMMITTEE MEMBERS:
Interno - 2394627 - EDUARDO BOUTH SEQUERRA
Interna - 1976236 - EMELIE KATARINA SVAHN LEAO
Presidente - 1996111 - MARTIN PABLO CAMMAROTA