Effect of amphetamine, cocaine and depolarization by high potassium on extracellular dopamine in the nucleus accumbens shell of SHR rats. An in vivo microdyalisis study

Abstract The basolateral amygdala (BLA) and ventral subiculum (vSub) of the hippocampus convey emotion and context information, respectively, to the nucleus accumbens (NAc). Using in vivo extracellular recordings from NAc neurons, we examined how acute and repeated restraint stress alters the plasticity of the vSub and BLA afferent pathways. High-frequency (HFS) and low-frequency (LFS) stimulation was applied to the vSub to assess the impact on NAc responses to vSub and BLA inputs. In addition, iontophoretic application of the dopamine D2-antagonist sulpiride was used to explore the role of dopamine in the NAc in mediating the effects of stress on plasticity. Acute and repeated restraint caused disparate effects on BLA- and vSub-evoked responses in the NAc. Following repeated restraint, but not after acute restraint, HFS of the vSub failed to potentiate the vSub–NAc pathway while instead promoting a long-lasting reduction of the BLA–NAc pathway and these effects were independent of D2-receptor activity. In contrast, LFS to the vSub pathway after acute restraint resulted in potentiation in the vSub–NAc pathway while BLA-evoked responses were unchanged. When sulpiride was applied prior to LFS of the vSub after acute stress, there was a pronounced decrease in vSub-evoked responses similar to control animals. This work provides new insight into the impact of acute and repeated stress on the integration of context and emotion inputs in the NAc. These data support a model of stress whereby the hippocampus is inappropriately activated and dominates the information processing within this circuit via a dopaminergic mechanism after acute bouts of stress.

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Cerebellar Activation Bidirectionally Regulates Nucleus Accumbens Shell and Core

10.1101/2020.09.28.283952 ◽

2020 ◽

Author(s):

Alexa D’Ambra ◽

Se Jung Jung ◽

Swetha Ganesan ◽

Evan G. Antzoulatos ◽

Diasynou Fioravante

Keyword(s):

Nucleus Accumbens ◽

Functional Connectivity ◽

Cerebellar Nuclei ◽

Brain Network ◽

Nucleus Accumbens Shell ◽

Control Center ◽

Electrical Microstimulation ◽

Excitatory Responses ◽

Motivated Behaviors

AbstractTraditionally viewed as a motor control center, the cerebellum (CB) is now recognized as an integral part of a broad, long-range brain network that serves limbic functions and motivates behavior. This diverse CB functionality has been at least partly attributed to the multiplicity of its outputs. However, relatively little attention has been paid to CB connectivity with subcortical limbic structures, and nothing is known about how the CB connects to the nucleus accumbens (NAc), a complex striatal region with which the CB shares functionality in motivated behaviors. Here, we report findings from in vivo electrophysiological experiments that investigated the functional connectivity between CB and NAc. We found that electrical microstimulation of deep cerebellar nuclei (DCN) modulates NAc spiking activity. This modulation differed in terms of directionality (excitatory vs. inhibitory) and temporal characteristics, in a manner that depends on NAc subregions: in the medial shell of NAc (NAcMed), slow inhibitory responses prevailed over excitatory ones, whereas the proportion of fast excitatory responses was greater in the NAc core (NAcCore) compared to NAcMed. Slow inhibitory modulation of NAcCore was also observed but it required stronger CB inputs compared to NAcMed. Finally, we observed shorter onset latencies for excitatory responses in NAcCore than in NAcMed, which argues for differential connectivity. If different pathways provide signal to each subregion, the divergence likely occurs downstream of the CB because we did not find any response-type clustering within DCN. Because there are no direct monosynaptic connections between CB and NAc, we performed viral tracing experiments to chart disynaptic pathways that could potentially mediate the newly discovered CB-NAc communication. We identified two anatomical pathways that recruit the ventral tegmental area and intralaminar thalamus as nodes. These pathways and the functional connectivity they support could underlie CB’s role in motivated behaviors.

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Ventral arkypallidal neurons modulate accumbal firing to promote reward consumption

10.1101/2020.04.01.020099 ◽

2020 ◽

Cited By ~ 1

Author(s):

Yvan M. Vachez ◽

Jessica R. Tooley ◽

Eric Casey ◽

Tom Earnest ◽

Kavitha Abiraman ◽

...

Keyword(s):

Nucleus Accumbens ◽

Inhibitory Input ◽

Nucleus Accumbens Shell ◽

Calcium Activity ◽

Consumption Behavior ◽

Synaptic Contacts ◽

Hedonic Value ◽

Reward Value

ABSTRACTA pause in firing of nucleus accumbens shell (NAcSh) neurons is critical for reward consumption; however, the substrate driving this pause is unknown. While ventral pallidal (VP) activity encodes reward value, the specific roles of VP subpopulations in computation and expression of this value are poorly understood. Here, we establish that inhibitory input from the VP is crucial for reward-related inhibition of NAc firing. A sparse, non-canonical subpopulation of VP neurons, the so-called “ventral arkypallidal (vArky)” neurons makes inhibitory synaptic contacts throughout the NAcSh, and drives inhibition of NAcSh neurons in vivo. Moreover, endogenous calcium activity of vArky neurons predicted subsequent reward consumption behavior, while optogenetically activating this pathway increased reward consumption by amplifying hedonic value of reward. Classically, the VP is considered downstream of the NAc; however, our results challenge this view and establish that vArky neurons in the VP promote reward consumption via potent modulation of NAcSh firing.

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Descending projections from the nucleus accumbens shell excite activity of taste-responsive neurons in the nucleus of the solitary tract in the hamster

Journal of Neurophysiology ◽

10.1152/jn.00362.2014 ◽

2015 ◽

Vol 113 (10) ◽

pp. 3778-3786 ◽

Cited By ~ 2

Author(s):

Cheng-Shu Li ◽

Da-Peng Lu ◽

Young K. Cho

Keyword(s):

Nucleus Accumbens ◽

Electrophysiological Study ◽

Neuronal Firing ◽

Solitary Tract ◽

Nucleus Accumbens Shell ◽

Descending Input ◽

Parabrachial Nuclei ◽

Gustatory Neurons ◽

Stimulation Of

The nucleus of the solitary tract (NST) and the parabrachial nuclei (PbN) are the first and second relays in the rodent central taste pathway. A series of electrophysiological experiments revealed that spontaneous and taste-evoked activities of brain stem gustatory neurons are altered by descending input from multiple forebrain nuclei in the central taste pathway. The nucleus accumbens shell (NAcSh) is a key neural substrate of reward circuitry, but it has not been verified as a classical gustatory nucleus. A recent in vivo electrophysiological study demonstrated that the NAcSh modulates the spontaneous and gustatory activities of hamster pontine taste neurons. In the present study, we investigated whether activation of the NAcSh modulates gustatory responses of the NST neurons. Extracellular single-unit activity was recorded from medullary neurons in urethane-anesthetized hamsters. After taste response was confirmed by delivery of sucrose, NaCl, citric acid, and quinine hydrochloride to the anterior tongue, the NAcSh was stimulated bilaterally with concentric bipolar stimulating electrodes. Stimulation of the ipsilateral and contralateral NAcSh induced firings from 54 and 37 of 90 medullary taste neurons, respectively. Thirty cells were affected bilaterally. No inhibitory responses or antidromic invasion was observed after NAcSh activation. In the subset of taste cells tested, high-frequency electrical stimulation of the NAcSh during taste delivery enhanced taste-evoked neuronal firing. These results demonstrate that two-thirds of the medullary gustatory neurons are under excitatory descending influence from the NAcSh, which is a strong indication of communication between the gustatory pathway and the mesolimbic reward pathway.

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