Excitatory and inhibitory ensembles of the dorsal medial prefrontal cortex during the strengthening and weakening of an appetitive association

Brebner, Leonie Sophie (2019) Excitatory and inhibitory ensembles of the dorsal medial prefrontal cortex during the strengthening and weakening of an appetitive association. Doctoral thesis (PhD), University of Sussex.

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Abstract

Animals associate relevant signals or ‘cues’ to food in order to efficiently gather nutrients. Sparse sets of neurons called ‘neuronal ensembles’ in the dorsal medial prefrontal cortex (dmPFC) play a vital role in associative memory formation. However, how these neurons are recruited into an ensemble to establish appetitive ‘food-cue’ associations during conditioning remains unclear.
The aims of this study were twofold: 1) examine the recruitment of both pyramidal cell and interneuron ensembles during the establishment and extinction of appetitive associations in the dmPFC and 2) investigate their function in appetitive conditioning.
Here, we took advantage of a microprism-based 2-photon imaging procedure to longitudinally image the dmPFC of Fos-GFP x GAD-tdTomato transgenic mice in vivo. These mice express GFP in strongly activated (Fos expressing) neurons and tdTomato in interneurons, which allowed us to track recently activated pyramidal cells and interneurons over conditioning and extinction. During conditioning, in which behavioural responding became cue-selective, a stable, repeatedly activated neuronal ensemble was recruited from a pyramidal cell pool activated during early learning. Furthermore, repeatedly enhancing the excitability of the initial learning activated pool with chemogenetics throughout training disrupted appetitive learning. In contrast, during extinction, a stable inhibitory ensemble emerged from interneurons activated in early extinction learning.
These novel findings reveal ensemble recruitment patterns occurring in the dmPFC during alterations in the strength of food-cue associations.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Life Sciences > Neuroscience
Subjects: Q Science > QL Zoology > QL0750 Animal behaviour > QL0756.5 Food
Q Science > QP Physiology > QP0351 Neurophysiology and neuropsychology
Depositing User: Library Cataloguing
Date Deposited: 21 Nov 2019 11:27
Last Modified: 21 Nov 2019 11:27
URI: http://sro.sussex.ac.uk/id/eprint/88151

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