Institutional creator:

Instytut Biologii Doświadczalnej im. Marcelego Nenckiego PAN

Contributor:

Kossut, Małgorzata : Supervisor

Publisher:

Instytut Biologii Doświadczalnej im. Marcelego Nenckiego PAN

Place of publishing:

Warszawa

Description:

251 pages : illustrations ; 30 cm ; Bibliography ; Summary in English

Degree name:

PhD in Biological Sciences

Degree discipline :

biological sciences

Degree grantor:

Nencki Institute of Experimental Biology PAS ; degree obtained in 2024

Type of object:

Thesis

Abstract:

Plasticity is a key feature of virtually all brains. It is hypothesized to underpin learning and memory and plays an important role in the early development of brain circuits. However, plasticity is not limited to developmental phases. This capacity is preserved in adulthood in the mammalian visual cortex and other basic sensory centers. Partial retinal lesions are a well-established model for inducing adult plasticity in the visual cortex, but our knowledge about how the inhibitory network contributes to brain plasticity remains incomplete. Somatostatin (SST-IN) interneurons constitute a significant neocortical subpopulation of interneurons, along with parvalbumin (PV-IN) and vasoactive intestinal peptide (VIP- IN) interneurons. Unlike the extensively studied PV-interneurons, which are acknowledged as key components in guiding ocular dominance plasticity, the contribution of SST-interneurons is less understood because neuroplasticity has only been more intensively studied in the last decade. In this dissertation, a fear conditioning mouse model was used to investigate plasticity in adults by recording the activity of the entire primary visual cortex (V1), with a particular emphasis on the role of plastic changes induced by learning through different interneurons expressing SST-IN and PV-IN. In the first stage of this study, an intrinsic signal optical imaging (ISOI) technique was used to investigate the stimulus orientation sensitivities of neurons in the mouse visual cortex in vivo. Optical signals from the right and left V1 cortex were recorded in response to moving black and white bars. ISOI allowed cortical activity to be recorded in the form of activation maps and optical signals. The second stage was devoted to investigating the effects of classical conditioning, in which orientation- specific visual stimuli were coupled to caudal current application (UCS). Animals were divided into experimental groups: those subjected to full classical conditioning, pseudoclassical conditioning, and exposure only to visual stimuli. The learning indicator was the induction of conditioned bradycardia. Training sessions lasted 10 minutes each for seven consecutive days. ECG was monitored during the training. Twenty-four hours after training, its effect on visual cortex V1 activity was recorded using the ISOI technique. It was found that conditioning led to increased activation strength in the visual cortex compared to the control group. Additionally, assessment of the active areas' size revealed a concentration of activity. The third step was to investigate the importance of SST-IN in the process of plastic changes induced by conditioning and their involvement in the activation of visual cortex V1. It was investigated whether the experimental procedures used affected the abundance of SST-IN and PV-IN in different areas of the visual cortex, in all its layers. After finding changes in SST-IN abundance in the conditioned group, it was tested whether chemogenetic silencing of SST-IN would affect the outcome of conditioning. SST interneurons appear to play a key role in the occurrence of plastic conditioning-induced changes, as the experimental group in which SST-IN activity was blocked using DREADD did not show changes induced by classical conditioning. These findings affirm the utility of ISOI as a technique for imaging the activity of large neuron populations in the mouse visual cortex, allowing for the characterization of orientation sensitivity, as well as changes in light scattering response amplitudes during ISOI registration. The study demonstrated that SST-IN activity in the cortex is essential for forming associations between conditioned and unconditioned stimuli, confirming its crucial role in shaping neuroplastic changes related to conditioning.

Detailed Resource Type:

PhD Dissertations

Resource Identifier:

oai:rcin.org.pl:242439

Source:

IBD PAN, call no. 20523

Language:

pol

Language of abstract:

eng

Rights:

Rights Reserved - Free Access

Terms of use:

Copyright-protected material. May be used within the limits of statutory user freedoms

Copyright holder:

Publication made available with the written permission of the author

Digitizing institution:

Nencki Institute of Experimental Biology of the Polish Academy of Sciences

Original in:

Library of the Nencki Institute of Experimental Biology PAS

Access:

Open