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Westphal, A. M.

Publications and source records attributed to Westphal, A. M..

4 recordsLinked to original sources

Cortical astrocytes flexibly encode reward contingencies and shape conditioned behavior

Learned associations between environmental cues and reward drive motivated behavior, yet how specific cell types support this process remains unclear. Using longitudinal two-photon calcium imaging, we tracked dorsal medial prefrontal cortical astrocytes throughout the acquisition, expression, and reversal of Pavlovian sucrose conditioning. As learning progressed, astrocytes exhibited time-locked, spatially coordinated calcium signals that differentiated correct behavioral action from mistakes, evolving from broad outcome encoding to selective representation of responses associated with the reward-conditioned stimulus. Omission testing revealed that prefrontal astrocytes preferentially respond to the cue-reward association, rather than the conditioned stimulus or reward alone. When reward contingencies were reversed, astrocytic activity rapidly adapted to track the new cue-reward association and encode updated and outdated motivated behavioral actions. Finally, astrocytic ablation attenuated motivated behavior during initial associative learning and prevented persistence of conditioned reward seeking when reward contingencies were updated or unpredictable. These findings reveal prefrontal astrocytes are functionally plastic elements that regulate reward-seeking behavior across associative learning. TeaserPrefrontal astrocytes flexibly encode the cue-reward associations that drive conditioned reward-seeking behavior.

neuroscience↗

Corticostriatal ensemble dynamics across heroin self-administration to reinstatement

Corticostriatal projection neurons from prelimbic medial prefrontal cortex to the nucleus accumbens core critically regulate drug-seeking behaviors, yet the underlying encoding dynamics whereby these neurons contribute to drug seeking remain elusive. Here we use two-photon calcium imaging to visualize the activity of corticostriatal neurons in mice from the onset of heroin use to relapse. We find that the activity of these neurons is highly heterogeneous during heroin self-administration and seeking, with at least 8 distinct neuronal ensembles that display both excitatory and inhibitory encoding dynamics. These neuronal ensembles are particularly apparent during relapse, where excitatory responses are amplified compared to heroin self-administration. Moreover, we find that optogenetic inhibition of corticostriatal projection neurons attenuates heroin seeking regardless of the relapse trigger. Our results reveal the precise corticostriatal activity dynamics underlying drug-seeking behaviors and support a key role for this circuit in mediating relapse to drug seeking.

neuroscience↗

Accumbens Nitrergic Interneurons Drive the Cell Type-Specific Synaptic Plasticity Required for Cue-Induced Cocaine Seeking

Cocaine use disorder (CUD) remains a serious public health crisis, with relapse vulnerability continuing to pose the largest impediment to effective clinical treatment. Relapse to cocaine seeking is often triggered by drug craving evoked by exposure to drug-associated environmental cues. Data from preclinical models of rodent self-administration (SA) and cue-induced reinstatement demonstrate that exposure to drug predictive cues following a period of withdrawal engages a large induction of glutamate release in the nucleus accumbens core (NAc), not observed during cued sucrose seeking. This profound glutamate release engages neuronal nitric oxide synthase (nNOS) expressing interneurons likely through activation of metabotropic glutamate receptor 5 (mGluR5), leading to increased production of nitric oxide (NO). Importantly, cue-induced glutamate and NO production have been linked to activation of matrix metalloproteinases (MMPs) and induction of the transient synaptic plasticity in medium spiny neurons (MSNs) required for cued cocaine seeking. Recent evidence suggests that cue-induced structural and synaptic plasticity occurs predominantly in D1 Dopamine receptor expressing MSNs, yet despite these findings, how cue-induced glutamate release is translated into D1 MSN plasticity has yet to be elucidated. We show here that knockdown of nNOS is sufficient to block cue-induced reinstatement to cocaine and prevents cue-induced functional and structural synaptic adaptions specifically in D1 receptor containing MSNs. Next, we demonstrate that knockdown of mGluR5, selectively on nitrergic interneurons in the NAc, is sufficient to block both conditioned place preference (CPP) and cue-induced reinstatement to cocaine, mechanistically linking cue-associated glutamate release to NO signaling. Finally, we demonstrate that downstream of glutamate-mediated activation of mGluR5 on nitrergic interneurons and MMP activation, expression of {beta}3 integrin receptors on D1 MSNs is required for cued cocaine seeking. Taken together, our data provide a mechanistic link between cocaine cue-induced glutamate release, activation of nitrergic interneurons and the D1 MSN plasticity required for cued cocaine seeking, Significance StatementRelapse vulnerability to cocaine is a persistent challenge to successful treatment of CUD. Relapse precipitated by drug-associated environment cues requires synaptic plasticity in MSNs. Here, we show that knockdown of nNOS, or mGluR5 on nitrergic interneurons, or {beta}3 integrin receptors on D1 MSNs is sufficient to block cue-induced cocaine seeking. Taken together our data support the following cocaine seeking signaling cascade. {square}Cocaine cues [->] PrL driven NAc glutamate release [->] mGluR5-mediated Activation of NAc nitrergic neurons [->] Activation of B3 integrins [->] D1 MSN plasticity [->] Reinstated Cocaine seeking.

neuroscience↗

A subset of nucleus accumbens neurons receiving dense and functional prelimbic cortical input are required for cocaine seeking

BackgroundPrelimbic cortical projections to the nucleus accumbens core are critical for cue-induced cocaine seeking, but the identity of the accumbens neuron(s) targeted by this projection, and the transient neuroadaptations contributing to relapse within these cells, remain unknown. MethodsMale Sprague-Dawley rats underwent cocaine or sucrose self-administration, extinction, and cue-induced reinstatement. Pathway-specific chemogenetics, patch-clamp electrophysiology, in vivo electrochemistry, and high-resolution confocal microscopy were used to identify and characterize a small population of nucleus accumbens core neurons that receive dense prelimbic cortical input to determine their role in regulating cue-induced cocaine and natural reward seeking. ResultsChemogenetic inhibition of prelimbic cortical projections to the nucleus accumbens core suppressed cue-induced cocaine relapse and normalized real-time cue-evoked increases in accumbens glutamate release to that of sucrose seeking animals. Furthermore, chemogenetic inhibition of the population of nucleus accumbens core neurons receiving the densest prelimbic cortical input suppressed cocaine, but not sucrose seeking. These neurons also underwent morphological plasticity during the peak of cocaine seeking in the form of dendritic spine expansion and increased ensheathment by astroglial processes at large spines. ConclusionsWe identified and characterized a unique subpopulation of nucleus accumbens neurons that receive dense prelimbic cortical input. The functional specificity of this subpopulation is underscored by their ability to mediate cue-induced cocaine relapse, but not sucrose seeking. This subset of cells represents a novel target for addiction therapeutics revealed by anterograde targeting to interrogate functional circuits imbedded within a known network.

neuroscience↗