Dopamine neurons

…learning (RL) algorithm in which dopamine (DA) neurons transmit reward prediction error (RPE) signals---the difference between actual and expected rewards---to enable value learning via cortico-striatal plasticity. Recent studies have highlighted two novel aspects: first, that RPE signals from midbrain DA neurons can encode entire reward distributions through a distributional RL algorithm that mirrors cutting-edge machine

The role of midbrain dopamine neurons in signalling reward prediction is well established, but it is becoming increasingly evident that these signals are heterogeneous. This raises the possibility that dopamine signalling during reward-seeking may vary in different striatal regions. We therefore examined dopamine signalling in the nucleus accumbens (NAc), dorsolateral striatum (DLS) or dorsomedial striatum (DMS) during choice and reward. We developed a mouse decision-making task and measured dopamine signals using fiber photometry. We expressed the GCaMP6f calcium sensor in the ventral tegment

…agonism inhibits GABAergic VTA interneurons, thereby disinhibiting dopamine release from nucleus accumbens-projecting VTA neurons. This GABA disinhibition circuit canonically drives opioid-induced reward and opioid-seeking in the VTA. However, we recently discovered MOR-expressing VTA neurons that release glutamate. In opposition to the classic GABA disinhibition model, MOR agonism on glutamatergic VTA neurons decreases activity in VTA dopamine neurons. Here, we investigated the role of GABA-

…in sleep homeostasis is attributed to neurons projecting to the dorsal fan-shaped body (dFB), which store sleep need via their intrinsic excitability. Here, we test if and how dFB neurons incorporate this intrinsic account of sleep drive into their network activity. In vivo dFB neuron ensemble activity is rhythmic, with a peak at 0.2-1 Hz (measured via calcium imaging). The amplitude of these slow oscillations increases with sleep drive,

…promoting consistent burst firing of dopamine neurons. Besides, sensitive and advanced research techniques led to the recognition of the mesohippocampal dopaminergic terminals, particularly in the two hippocampal regions, CA1 and dentate gyrus (DG). Previous studies have shown that dopamine receptors within these two hippocampal regions play a critical role in antinociceptive responses induced by forced swim stress (FSS) in the presence of inflammatory pain. S

Despite an increasing number of studies describing changes in dopamine brain regions and autism symptoms, the specific alterations in midbrain dopamine neurons projecting to the striatum remain unclear. Therefore, the aim of the present study was to examine the structural and morphological properties of primary dopaminergic neuronal cell cultures isolated from Shank3-deficient transgenic mouse, known for exhibiting autism-like symptomatology. Additionally, we evaluated the expression of selected synaptic proteins in the brain areas relevant for social behavior in wild type (WT) and Shank3-defi

…VTA dopamine (VTA-DA) neurons encode reward and reward-predicting cues heterogeneously. Moreover, individual neurons respond to different behavioural and kinematic variables. However, it remains unclear whether individual dopamine neurons respond to competing rewards like feeding and voluntary exercise heterogeneously. Additionally, it is unknown how motivational state changes, such as hunger or enhanced exercise drive, in

…somatostatin-expressing (Sst+) GPi-LHb neurons project to key nodes in the basal ganglia: the GPe, the striatal striosomes, and dopamine neurons in the SNc. Calcium imaging coupled with unsupervised behavioral segmentation revealed that activity of Sst+ GPi-LHb neurons is strongly linked with motor actions during exploration in an open field arena. On the other hand, in a maze-based choice task, the activity of Sst+ GPi-LHb neurons showed a gradual suppression over days as mice

…the potential involvement of dopamine transmission in these behavioral changes. Maternal CUS and mirtazapine were administered as previously described. Adult offspring were anesthetized with chloral hydrate and electrodes were placed in the ventral tegmental area. Dopamine neurons were detected and recorded. We found no

The degeneration of dopamine neurons of the substantia nigra pars compacta is well-known in motor symptoms of Parkinson’s disease (PD). However, other dopaminergic populations degenerate and give rise to non-motor symptoms such as anxiety which has a high prevalence in PD patients and strongly affects quality of life. One of these structures, the dorsal raphe nucleus (DRN), has been identified as a potential structure involved in anxiety and depression in PD. Indeed, the dopaminergic neurons of the DRN degenerate in PD, and a part of them co-releases the vaso-intestinal peptide (VIP) onto two

…identification of phasic activity in dopamine neurons as a reward prediction error signal that drives learning in basal ganglia and prefrontal circuits. However, recent findings suggest that dopaminergic prediction error signals have access to complex, structured reward predictions and are sensitive to more properties of outcomes than learning theories with simple scalar value predictions might suggest.

…an algorithm that predicts tuning of dopamine neurons to a quantity we call "action surprise," in addition to reward prediction error. In the same model, an implementation of learning from a motor efference copy also predicts a novel

The predominant theory of ventral tegmental area (VTA) dopamine neuron function is that they signal reward prediction error (RPE) in their phasic activity. Some recent studies have observed ramping dopamine neuron activity, but its relationship to RPE signalling is currently under debate. We set out to explain the function of this ramp and its relationship to phasic RPEs, using both experimental and theoretical methods. We chose to examine goal-directed navigation, as it requires learning to accurately estimate location and select optimal actions in each location. Given that VTA dopamine neuro

…mushroom body (MB), ~20 pairs of dopamine neurons (DANs) and mushroom body output neurons (MBON) together form compartmental units of associative learning. Each DAN cell type is selectively tuned to rewards or punishments and write and update memories with cell-type-s

Human movement disorders and pharmacological studies have long suggested molecular dopamine modulates the pace of the internal clock. But how does the endogenous dopaminergic system influence the timing of our movements? We examined the relationship between dopaminergic signaling and the timing of reward-related, self-timed movements in mice. Animals were trained to initiate licking after a self-timed interval following a start cue; reward was delivered if the animal’s first lick fell within a rewarded window (3.3-7 s). The first-lick timing distributions exhibited the scalar property, and we

In behaving rodents, CA1 pyramidal neurons receive spatially-tuned depolarizing synaptic input while traversing a specific location within an environment called its place. Midbrain dopamine neurons participate in reinforcement learning, and bursts of action potentials riding a depolarizing wave of synaptic input signal rewards and reward expectation. Interestingly, slice electrophysiology in vitro shows that both types of cells exhibit a pronounced reduction in firing rate (adaptation) and even cessation of firing during sustained depolarization. We included a five state Markov model of NaV1.6

…that orbitofrontal cortex and midbrain dopamine neurons represent the subjective value of knowledge during information seeking behavior. However, it remains un