Banca de QUALIFICAÇÃO: JÉSSICA WINNE RODRIGUES DE FREITAS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JÉSSICA WINNE RODRIGUES DE FREITAS
DATE: 13/12/2021
TIME: 09:30
LOCAL: GOOGLE MEET - meet.google.com/qzt-wxqu-eiw
TITLE:

Electrophysiological correlates of the hippocampus and medial prefrontal cortex in an animal model of tinnitus and in response to activation of a non-canonical central auditory pathway

KEY WORDS:

Hippocampus, Theta oscillation, Tinnitus, anxiety, calcium imaging, noncanonical auditory pathway.

PAGES: 90
BIG AREA: Ciências Biológicas
AREA: Fisiologia
SUMMARY:

In this work, we investigate the electrophysiological correlates of the hippocampus and medial prefrontal cortex in an animal model of tinnitus, based on a high-dose salicylate, and in the response to a high-intensity broadband noise stimuli in healthy mice during the locomotion. We explored a noncanonical auditory pathway, and through hippocampal calcium imaging we recorded the activity of excitatory and inhibitory neurons in response to sound and speed simultaneously. We present the main results in 4 manuscripts organized in three experimental articles (1, 2 and 4) and a book chapter (3). In the first article (Winne et al. 2019), we found that a high dose of salicylate (300mg/kg) induced type 2 theta (4 to 6) Hz in the ventral hippocampus (VHipp) and an anxiety-like behavior in animals. In addition, dorsal hippocampal type 1 theta (7 to 10) Hz (DHipp) had its correlation with running speed abolished. In the second article (Winne et al. 2020), we found that after pretreatment with salicylate, only young mice with preserved hearing exhibited anxiety like behavior. It was also
observed both an increase in type 2 theta oscillations and slow gamma (30 to 60) Hz, in VHipp and in the medial prefrontal cortex (CPFm). We also noticed an increased theta 2 coherence between these areas after pretreatment with salicylate when animals were in an anxiogenic environments. And finally, the pretreatment of mice with a single dose of the hallucinogen 5-MeO-DMT, prevented the emergence of anxiety-associated behaviors and the induction of type 2 and slow gamma theta after salicylate injection. Together, the articles 1 and 2 indicates that anxiety-related mechanisms are also related to tinnitus, based on electrophysiological and behavioral evidence. In the Chapter 3 (Winne et al., 2021), we discussed about a technique of calcium imaging to animals in freely moving, using mini-endoscopes. We describe the lens and baseplate implant surgery for the UCLA Miniscope V3 and V4. We used GRIN lens for the hippocampus, and a combination of prism and GRIN lens for the neocortex. We detail protocols that contain adaptations from other groups work, already published, and one developed in our laboratory for lens fixation (GRIN-relay-Prism). Finally, we comment on the differences between analysis software and the computational needs for this step. Finally, in the article 4, that is still in the process of being finalized for publication, we address a non-canonical auditory pathway that we demonstrate to provide auditory information for the polysensory integration of the entorhinal cortex and dorsal hippocampus (DHipp) and is activated by broadband noise stimuli. Using sound stimulation/inhibition, chemogenetics, and optogenetics, we found that the type 1 theta oscillations abolished correlation with speed when this non-canonical pathway is activated, and that they simultaneously show increased frequency and decreased power in the dorsal hippocampus. We also verified that the activation of this pathway induced an increase in coherence between the DHipp and medial prefrontal cortex. Through calcium imaging, we evidenced alterations in the firing pattern of interneurons and pyramidal neurons of the dorsal hippocampus in response to broadband sounds of intensities above 80db. We presume that sensitizing DHipp neurons to auditory stimuli by somehow, could help to quickly identify dangerous environments and increase the alertness of animals in response to possible environmental threats.

BANKING MEMBERS:
Interno - 2394627 - EDUARDO BOUTH SEQUERRA
Interno - 1696755 - BRUNO LOBAO SOARES
Presidente - 1764910 - GEORGE CARLOS DO NASCIMENTO