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Interrogating Basolateral Amygdala Activity during Social Behaviour at Single-Cell and Population Levels

Periodic Reporting for period 1 - AMYGDALA-ELECTROPHYS (Interrogating Basolateral Amygdala Activity during Social Behaviour at Single-Cell and Population Levels)

Reporting period: 2019-05-01 to 2021-04-30

Accurately processing and integrating the social environment is crucial for the survival of social species including rodents, primates and humans. During this MSCA-IF fellowship titled ‘Interrogating Basolateral Amygdala Activity during Social Behaviour at Single-Cell and Population Levels’, we set out to understand how neurons within basolateral amygdala (BLA) contribute to the representation of social stimuli during naturalistic interactions. Understanding the neural computation within the BLA during social behaviour may provide insights into the neural mechanisms underlying neuropsychiatric conditions such as autism, mood disorders and anxiety.

To answer these questions, the fellow recorded from hundreds of BLA neurons using neuropixel probes during naturalistic behaviour in the rat. The resulting dataset was analyzed at single-cell and population levels to understand how the BLA represents etiologically relevant behaviour.
During this fellowship, we had 4 specific scientific objectives. Below, we will briefly outline the results achieved for each of these objectives.
I. Collect large-scale electrophysiological recordings from the BLA during free social interaction. We successfully used neuropixel probes to record from hundreds of neurons within the BLA of freely-moving rats while presenting a battery of social and non-social stimuli. All events were videotaped to allow for offline tracking and automated analysis of behaviour. The large amounts of data collected from this specific objective formed the basis for objectives II and III.
II. Correlate Single Unit Activity with Social Behaviour. We identified functional types of BLA neurons based on their responses to the presented stimuli.
III. Decode Population Activity during Social Behaviour. Since we were recording from up to 120 BLA neurons simultaneously within a single rat, we were able to test what information about the stimulus is present at the BLA circuit level.
IV. Identify the activity of anatomically-defined ensembles of BLA neurons. During the fellowship period, we tested different methods for optically tagging molecularly defined populations of BLA neurons including transgenic rats and different viral methods.

At the conclusion of this fellowship, we are actively working towards publishing the results in a peer-reviewed open-access journal. Upon publication all the data and code used for that publication will be made freely available upon request.
The results achieved during this fellowship will help push the boundaries of knowledge on how the brain, and specifically the basolateral amygdala, perceives and interprets etiologically relevant events. Though this is basic scientific research, these results may help to understand the mechanisms behind social dysfunction in neuropsychiatric disorders such as autism, mood disorders and anxiety. In the immediate future, the rich dataset collected as part of this fellowship can provide preliminary data for future experiments.

The technical experimental advances achieved during this fellowship have immediate benefits for the fellow and the adjacent neuroscientific community. Specifically, the surgical techniques that were refined during this fellowship allow for consistent and reliable extracellular neuronal recordings and the automated behavioural analyses permit complex analysis of social behaviour that was previously labour-intensive.
Diagram of rat brain showing proposed recording site