Differential recruitment of ventral pallidal e-types by behaviorally salient stimuli during Pavlovian conditioning

Panna Hegedüs,Julia Heckenast,Balázs Hangya

doi:10.1016/j.isci.2021.102377

Panna Hegedüs, Julia Heckenast + Show 1 more

Open Access

https://doi.org/10.1016/j.isci.2021.102377

Copy DOI

Abstract

SummaryThe ventral pallidum (VP) is interfacing striatopallidal and limbic circuits, conveying information about salience and valence crucial to adjusting behavior. However, how VP neuron populations with distinct electrophysiological properties (e-types) represent these variables is not fully understood. Therefore, we trained mice on probabilistic Pavlovian conditioning while recording the activity of VP neurons. Many VP neurons responded to punishment (54%), reward (48%), and outcome-predicting auditory stimuli (32%), increasingly differentiating distinct outcome probabilities through learning. We identified e-types based on the presence of bursts or fast rhythmic discharges and found that non-bursting, non-rhythmic neurons were the most sensitive to reward and punishment. Some neurons exhibited distinct responses of their bursts and single spikes, suggesting a multiplexed coding scheme in the VP. Finally, we demonstrate synchronously firing neuron assemblies, particularly responsive to reinforcing stimuli. These results suggest that electrophysiologically defined e-types of the VP differentially participate in transmitting reinforcement signals during learning.

Highlights

The ventral pallidum (VP) serves as an interface between the limbic system and other structures, integrating cortical, amygdala, basal ganglia, and neuromodulatory input (Root et al, 2015; Zaborszky and Cullinan, 1992)
Many VP neurons responded to punishment (54%), reward (48%), and outcome-predicting auditory stimuli (32%), increasingly differentiating distinct outcome probabilities through learning
We identified e-types based on the presence of bursts or fast rhythmic discharges and found that non-bursting, non-rhythmic neurons were the most sensitive to reward and punishment

Summary

Introduction

The ventral pallidum (VP) serves as an interface between the limbic system and other structures, integrating cortical, amygdala, basal ganglia, and neuromodulatory input (Root et al, 2015; Zaborszky and Cullinan, 1992). Whether they are routed through different lines of this intricate switch board, labeled by markers such as parvalbumin, the vesicular glutamate transporter VGluT2, or the inhibitory marker GAD2 has been explored recently (Faget et al, 2018; Knowland et al, 2017; Prasad et al, 2020; Stephenson-Jones et al, 2020; Wulff et al, 2019) Another exciting possibility is that integrating and multiplexing is represented by different coding schemes including elements of rate and temporal code, such as characteristic firing patterns like bursts or single spike firing, rhythmic discharges, network level synchrony, and asynchronous activity (Ascoli et al, 2008; Gouwens et al, 2019; de Vries et al, 2020). Avila and Lin suggest that electrophysiological characterization that goes beyond the broad categories of inhibitory and excitatory cell types will enable a better understanding of how VP performs its functions (Avila and Lin, 2014)

Objectives

Methods

Results

Discussion

Conclusion