Appetite suppression occurs after a meal and in conditions when it is unfavourable to eat, such as during illness or exposure to toxins. A brain region proposed to play a role in appetite suppression ...is the parabrachial nucleus, a heterogeneous population of neurons surrounding the superior cerebellar peduncle in the brainstem. The parabrachial nucleus is thought to mediate the suppression of appetite induced by the anorectic hormones amylin and cholecystokinin, as well as by lithium chloride and lipopolysaccharide, compounds that mimic the effects of toxic foods and bacterial infections, respectively. Hyperactivity of the parabrachial nucleus is also thought to cause starvation after ablation of orexigenic agouti-related peptide neurons in adult mice. However, the identities of neurons in the parabrachial nucleus that regulate feeding are unknown, as are the functionally relevant downstream projections. Here we identify calcitonin gene-related peptide-expressing neurons in the outer external lateral subdivision of the parabrachial nucleus that project to the laterocapsular division of the central nucleus of the amygdala as forming a functionally important circuit for suppressing appetite. Using genetically encoded anatomical, optogenetic and pharmacogenetic tools, we demonstrate that activation of these neurons projecting to the central nucleus of the amygdala suppresses appetite. In contrast, inhibition of these neurons increases food intake in circumstances when mice do not normally eat and prevents starvation in adult mice whose agouti-related peptide neurons are ablated. Taken together, our data demonstrate that this neural circuit from the parabrachial nucleus to the central nucleus of the amygdala mediates appetite suppression in conditions when it is unfavourable to eat. This neural circuit may provide targets for therapeutic intervention to overcome or promote appetite.
Recent evidence indicates that psilocybin with psychological support may be effective for treating depression. Some studies have found that patients with depression show heightened amygdala responses ...to fearful faces and there is reliable evidence that treatment with SSRIs attenuates amygdala responses (Ma, 2015). We hypothesised that amygdala responses to emotional faces would be altered post-treatment with psilocybin. In this open-label study, 20 individuals diagnosed with moderate to severe, treatment-resistant depression, underwent two separate dosing sessions with psilocybin. Psychological support was provided before, during and after these sessions and 19 completed fMRI scans one week prior to the first session and one day after the second and last. Neutral, fearful and happy faces were presented in the scanner and analyses focused on the amygdala. Group results revealed rapid and enduring improvements in depressive symptoms post psilocybin. Increased responses to fearful and happy faces were observed in the right amygdala post-treatment, and right amygdala increases to fearful versus neutral faces were predictive of clinical improvements at 1-week. Psilocybin with psychological support was associated with increased amygdala responses to emotional stimuli, an opposite effect to previous findings with SSRIs. This suggests fundamental differences in these treatments’ therapeutic actions, with SSRIs mitigating negative emotions and psilocybin allowing patients to confront and work through them. Based on the present results, we propose that psilocybin with psychological support is a treatment approach that potentially revives emotional responsiveness in depression, enabling patients to reconnect with their emotions.
ISRCTN, number ISRCTN14426797.
This article is part of the Special Issue entitled ‘Psychedelics: New Doors, Altered Perceptions’.
•Psilocybin with psychological support was used successfully to treat depression.•Amygdala responses to fearful faces were increased one day after psilocybin session.•Increased amygdala responses predicted positive clinical outcomes.•Psilocybin assisted therapy treats depression by reviving emotional responsiveness.
Single-cell RNA sequencing offers a promising opportunity for probing cell types mediating specific behavioral functions and the underlying molecular programs. However, this has been hampered by a ...long-standing issue in transcriptional profiling of dissociated cells, specifically the transcriptional perturbations that are artificially induced during conventional whole-cell dissociation procedures. Here, we develop Act-seq, which minimizes artificially induced transcriptional perturbations and allows for faithful detection of both baseline transcriptional profiles and acute transcriptional changes elicited by behavior/experience-driven activity. Using Act-seq, we provide the first detailed molecular taxonomy of distinct cell types in the amygdala. We further show that Act-seq robustly detects seizure-induced acute gene expression changes in multiple cell types, revealing cell-type-specific activation profiles. Furthermore, we find that acute stress preferentially activates neuronal subpopulations that express the neuropeptide gene Cck. Act-seq opens the way for linking physiological stimuli with acute transcriptional dynamics in specific cell types in diverse complex tissues.
•Act-seq minimizes artificial transcriptional changes during tissue dissociation•Act-seq enables unbiased characterization of cell types and their acute activation•Application of Act-seq provides the first molecular taxonomy in the amygdala•Application of Act-seq identifies neuronal subpopulations activated by stress
Wu et al. develop Act-seq, which minimizes artificially induced transcriptional changes during single-cell dissociation and thus enables faithful characterization of baseline transcriptional profiles and detection of specific cell populations activated by physiological stimuli using single-cell sequencing.
To elucidate molecular, cellular, and circuit changes that occur in the brain during learning, we investigated the role of a glutamate receptor subtype in fear conditioning. In this form of learning, ...animals associate two stimuli, such as a tone and a shock. Here we report that fear conditioning drives AMPA-type glutamate receptors into the synapse of a large fraction of postsynaptic neurons in the lateral amygdala, a brain structure essential for this learning process. Furthermore, memory was reduced if AMPA receptor synaptic incorporation was blocked in as few as 10 to 20% of lateral amygdala neurons. Thus, the encoding of memories in the lateral amygdala is mediated by AMPA receptor trafficking, is widely distributed, and displays little redundancy.
Sexual and aggressive behaviors are fundamental to animal survival and reproduction. The medial preoptic nucleus (MPN) and ventrolateral part of the ventromedial hypothalamus (VMHvl) are essential ...regions for male sexual and aggressive behaviors, respectively. While key inhibitory inputs to the VMHvl and MPN have been identified, the extrahypothalamic excitatory inputs essential for social behaviors remain elusive. Here we identify estrogen receptor alpha (Esr1)-expressing cells in the posterior amygdala (PA) as a main source of excitatory inputs to the hypothalamus and key mediators for mating and fighting in male mice. We find two largely distinct PA subpopulations that differ in connectivity, gene expression, in vivo responses and social behavior relevance. MPN-projecting PA
cells are activated during mating and are necessary and sufficient for male sexual behaviors, while VMHvl-projecting PA
cells are excited during intermale aggression and promote attacks. These findings place the PA as a key node in both male aggression and reproduction circuits.
When extreme, anxiety-a state of distress and arousal prototypically evoked by uncertain danger-can be debilitating. Uncertain anticipation is a shared feature of situations that elicit signs and ...symptoms of anxiety across psychiatric disorders, species, and assays. Despite the profound significance of anxiety for human health and wellbeing, the neurobiology of uncertain-threat anticipation remains unsettled. Leveraging a paradigm adapted from animal research and optimized for fMRI signal decomposition, we examined the neural circuits engaged during the anticipation of temporally uncertain and certain threat in 99 men and women. Results revealed that the neural systems recruited by uncertain and certain threat anticipation are anatomically colocalized in frontocortical regions, extended amygdala, and periaqueductal gray. Comparison of the threat conditions demonstrated that this circuitry can be fractionated, with frontocortical regions showing relatively stronger engagement during the anticipation of uncertain threat, and the extended amygdala showing the reverse pattern. Although there is widespread agreement that the bed nucleus of the stria terminalis and dorsal amygdala-the two major subdivisions of the extended amygdala-play a critical role in orchestrating adaptive responses to potential danger, their precise contributions to human anxiety have remained contentious. Follow-up analyses demonstrated that these regions show statistically indistinguishable responses to temporally uncertain and certain threat anticipation. These observations provide a framework for conceptualizing anxiety and fear, for understanding the functional neuroanatomy of threat anticipation in humans, and for accelerating the development of more effective intervention strategies for pathological anxiety.
Anxiety-an emotion prototypically associated with the anticipation of uncertain harm-has profound significance for public health, yet the underlying neurobiology remains unclear. Leveraging a novel neuroimaging paradigm in a relatively large sample, we identify a core circuit responsive to both uncertain and certain threat anticipation, and show that this circuitry can be fractionated into subdivisions with a bias for one kind of threat or the other. The extended amygdala occupies center stage in neuropsychiatric models of anxiety, but its functional architecture has remained contentious. Here we demonstrate that its major subdivisions show statistically indistinguishable responses to temporally uncertain and certain threat. Collectively, these observations indicate the need to revise how we think about the neurobiology of anxiety and fear.
The ability to help and care for others fosters social cohesiveness and is vital to the physical and emotional well-being of social species, including humans
. Affiliative social touch, such as ...allogrooming (grooming behaviour directed towards another individual), is a major type of prosocial behaviour that provides comfort to others
. Affiliative touch serves to establish and strengthen social bonds between animals and can help to console distressed conspecifics. However, the neural circuits that promote prosocial affiliative touch have remained unclear. Here we show that mice exhibit affiliative allogrooming behaviour towards distressed partners, providing a consoling effect. The increase in allogrooming occurs in response to different types of stressors and can be elicited by olfactory cues from distressed individuals. Using microendoscopic calcium imaging, we find that neural activity in the medial amygdala (MeA) responds differentially to naive and distressed conspecifics and encodes allogrooming behaviour. Through intersectional functional manipulations, we establish a direct causal role of the MeA in controlling affiliative allogrooming and identify a select, tachykinin-expressing subpopulation of MeA GABAergic (γ-aminobutyric-acid-expressing) neurons that promote this behaviour through their projections to the medial preoptic area. Together, our study demonstrates that mice display prosocial comforting behaviour and reveals a neural circuit mechanism that underlies the encoding and control of affiliative touch during prosocial interactions.
The hypothalamic neuropeptide oxytocin (OT) has received increasing attention for its role in modulating social-emotional processes across species. Previous studies on using intranasal-OT in humans ...point to a crucial engagement of the amygdala in the observed neuromodulatory effects of OT under task and rest conditions. However, the amygdala is not a single homogenous structure, but rather a set of structurally and functionally heterogeneous nuclei that show distinct patterns of connectivity with limbic and frontal emotion-processing regions. To determine potential differential effects of OT on functional connectivity of the amygdala subregions, 79 male participants underwent resting-state fMRI following randomized intranasal-OT or placebo administration. In line with previous studies OT increased the connectivity of the total amygdala with dorso-medial prefrontal regions engaged in emotion regulation. In addition, OT enhanced coupling of the total amygdala with cerebellar regions. Importantly, OT differentially altered the connectivity of amygdala subregions with distinct up-stream cortical nodes, particularly prefrontal/parietal, and cerebellar down-stream regions. OT-induced increased connectivity with cerebellar regions were largely driven by effects on the centromedial and basolateral subregions, whereas increased connectivity with prefrontal regions were largely mediated by right superficial and basolateral subregions. OT decreased connectivity of the centromedial subregions with core hubs of the emotional face processing network in temporal, occipital and parietal regions. Preliminary findings suggest that effects on the superficial amygdala-prefrontal pathway were inversely associated with levels of subclinical depression, possibly indicating that OT modulation may be blunted in the context of increased pathological load. Together, the present findings suggest a subregional-specific modulatory role of OT on amygdala-centered emotion processing networks in humans.
•Effects of oxytocin (OT) on amygdala subregional rsFC were examined.•OT differentially altered rsFC of amygdala subregions.•Increased connectivity with PFC regions were driven by SF and BLA.•OT decreased rsFC of the CM with the face processing network.•Effects on the SF-mPFC pathway were associated with depression.
In mice, various instinctive behaviors can be triggered by olfactory input. Despite growing knowledge of the brain regions involved in such behaviors, the organization of the neural circuits that ...convert olfactory input into stereotyped behavioral output remains poorly understood. Here, we mapped the neural circuit responsible for enhancing sexual receptivity of female mice by a male pheromone, exocrine gland-secreting peptide 1 (ESP1). We revealed specific neural types and pathways by which ESP1 information is conveyed from the peripheral receptive organ to the motor-regulating midbrain via the amygdala-hypothalamus axis. In the medial amygdala, a specific type of projection neurons gated ESP1 signals to the ventromedial hypothalamus (VMH) in a sex-dependent manner. In the dorsal VMH, which has been associated with defensive behaviors, a selective neural subpopulation discriminately mediated ESP1 information from a predator cue. Together, our data illuminate a labeled-line organization for controlling pheromone-mediated sexual behavioral output in female mice.
•Sex pheromone information is sorted by the amygdala in a sexually dimorphic manner•A novel pathway from the hypothalamus to midbrain modulates female sexual behavior•Sex pheromone and predator cue signals are represented by mostly distinct neurons
Ishii et al. show a labeled-line neural circuitry for a sex pheromone, ESP1, that controls sexual receptivity of female mice. This circuit relays information in a sexually dimorphic manner, which is in line with the sex-dependent effects of ESP1.
The neural control of social behaviors in rodents requires the encoding of pheromonal cues by the vomeronasal system. Here we show that the typical preference of male mice for females is eliminated ...in mutants lacking oxytocin, a neuropeptide modulating social behaviors in many species. Ablation of the oxytocin receptor in aromatase-expressing neurons of the medial amygdala (MeA) fully recapitulates the elimination of female preference in males. Further, single-unit recording in the MeA uncovered significant changes in the sensory representation of conspecific cues in the absence of oxytocin signaling. Finally, acute manipulation of oxytocin signaling in adults is sufficient to alter social interaction preferences in males as well as responses of MeA neurons to chemosensory cues. These results uncover the critical role of oxytocin signaling in a molecularly defined neuronal population in order to modulate the behavioral and physiological responses of male mice to females on a moment-to-moment basis.
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