Banca de QUALIFICAÇÃO: ELIS HERCULANO DUARTE

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : ELIS HERCULANO DUARTE
DATE: 15/05/2026
TIME: 09:00
LOCAL: INSTITUTO DO CEREBRO - SALA DE REUNIÕES
TITLE:

Dynamics of freezing behavior across fear conditioning and extinction protocols in rats

KEY WORDS:

Aversive memory. Memory extinction. Freezing. Fear conditioning. Automated behavior analysis.

PAGES: 60
BIG AREA: Ciências Biológicas
AREA: Fisiologia
SUMMARY:

Fear is an adaptive defensive state that triggers autonomic, behavioral, and cognitive responses aimed at the organism's survival. In rodents, one of the most frequently observed responses during fear expression is freezing behavior, considered a primary marker for measuring aversive responses. In this study, we investigated the dynamics of this behavior in rats subjected to a fear conditioning, extinction, and aversive memory recall protocol. The protocol included habituation stages to the environment and sounds, conditioning with pairings between an aversive auditory stimulus (CS+) and a footshock, counterbalanced by a neutral stimulus (CS−), early and late extinction sessions, as well as recall tests for both extinction and aversive memories. Our analyses demonstrated that freezing probability does not rise instantaneously after stimulus onset; instead, it exhibits progressive growth over the subsequent seconds. This contrasts with the probability of movement, which follows an inverse profile, and the probability of immobility, which is not coupled with the stimulus onset. Comparisons between different time window sizes and window shifts relative to the CS+ onset demonstrated that freezing quantification is sensitive to both window length and the timing of the analysis onset. These findings led us to adopt a 20-second window for inter-session analyses, encompassing the final 10 seconds of the CS+ and the 10 seconds following the stimulus offset. Based on this definition, we observed that the highest freezing values were concentrated in the session immediately following conditioning, reflecting behavioral task learning—specifically, the association between the CS+ and the shock. As an additional tool for behavioral analysis, we also developed an automated motor immobility detection workflow based on body tracking and Random Forest supervised classification, which served as a screening strategy for subsequent behavioral analyses. In summary, our results indicate that the automated workflow was capable of generating suitable data for manual analysis, contributing to a reduction in review workload. Simultaneously, the findings from the behavioral analyses demonstrate the efficacy of the protocol in inducing aversive responses after conditioning and their progressive decrease throughout memory extinction.

COMMITTEE MEMBERS:
Presidente - 1721223 - ADRIANO BRETANHA LOPES TORT
Interna - 1976236 - EMELIE KATARINA SVAHN LEAO
Interno - 1698305 - RODRIGO NEVES ROMCY PEREIRA