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Science (New York, N.Y.) Oct 2023The human brain directs complex behaviors, ranging from fine motor skills to abstract intelligence, but the diversity of cell types that support these skills has not...
The human brain directs complex behaviors, ranging from fine motor skills to abstract intelligence, but the diversity of cell types that support these skills has not been fully described. In this work, we used single-nucleus RNA sequencing to systematically survey cells across the entire adult human brain. We sampled more than three million nuclei from approximately 100 dissections across the forebrain, midbrain, and hindbrain in three postmortem donors. Our analysis identified 461 clusters and 3313 subclusters organized largely according to developmental origins and revealing high diversity in midbrain and hindbrain neurons. Astrocytes and oligodendrocyte-lineage cells also exhibited regional diversity at multiple scales. The transcriptomic census of the entire human brain presented in this work provides a resource for understanding the molecular diversity of the human brain in health and disease.
Topics: Adult; Humans; Brain; Gene Expression Profiling; Mesencephalon; Neurons; Prosencephalon; Transcriptome; Single-Cell Gene Expression Analysis
PubMed: 37824663
DOI: 10.1126/science.add7046 -
Neuron Aug 2023Pain and itch are two closely related but essentially distinct sensations that elicit different behavioral responses. However, it remains mysterious how pain and itch...
Pain and itch are two closely related but essentially distinct sensations that elicit different behavioral responses. However, it remains mysterious how pain and itch information is encoded in the brain to produce differential perceptions. Here, we report that nociceptive and pruriceptive signals are separately represented and processed by distinct neural ensembles in the prelimbic (PL) subdivision of the medial prefrontal cortex (mPFC) in mice. Pain- and itch-responsive cortical neural ensembles were found to significantly differ in electrophysiological properties, input-output connectivity profiles, and activity patterns to nociceptive or pruriceptive stimuli. Moreover, these two groups of cortical neural ensembles oppositely modulate pain- or itch-related sensory and emotional behaviors through their preferential projections to specific downstream regions such as the mediodorsal thalamus (MD) and basolateral amygdala (BLA). These findings uncover separate representations of pain and itch by distinct prefrontal neural ensembles and provide a new framework for understanding somatosensory information processing in the brain.
Topics: Mice; Animals; Prefrontal Cortex; Neural Pathways; Thalamus; Basolateral Nuclear Complex; Pain
PubMed: 37224813
DOI: 10.1016/j.neuron.2023.04.032 -
Molecular Psychiatry Aug 2023Social behaviors, how individuals act cooperatively and competitively with conspecifics, are widely seen across species. Rodents display various social behaviors, and... (Review)
Review
Social behaviors, how individuals act cooperatively and competitively with conspecifics, are widely seen across species. Rodents display various social behaviors, and many different behavioral paradigms have been used for investigating their neural circuit bases. Social behavior is highly vulnerable to brain network dysfunction caused by neurological and neuropsychiatric conditions such as autism spectrum disorders (ASDs). Studying mouse models of ASD provides a promising avenue toward elucidating mechanisms of abnormal social behavior and potential therapeutic targets for treatment. In this review, we outline recent progress and key findings on neural circuit mechanisms underlying social behavior, with particular emphasis on rodent studies that monitor and manipulate the activity of specific circuits using modern systems neuroscience approaches. Social behavior is mediated by a distributed brain-wide network among major cortical (e.g., medial prefrontal cortex (mPFC), anterior cingulate cortex, and insular cortex (IC)) and subcortical (e.g., nucleus accumbens, basolateral amygdala (BLA), and ventral tegmental area) structures, influenced by multiple neuromodulatory systems (e.g., oxytocin, dopamine, and serotonin). We particularly draw special attention to IC as a unique cortical area that mediates multisensory integration, encoding of ongoing social interaction, social decision-making, emotion, and empathy. Additionally, a synthesis of studies investigating ASD mouse models demonstrates that dysfunctions in mPFC-BLA circuitry and neuromodulation are prominent. Pharmacological rescues by local or systemic (e.g., oral) administration of various drugs have provided valuable clues for developing new therapeutic agents for ASD. Future efforts and technological advances will push forward the next frontiers in this field, such as the elucidation of brain-wide network activity and inter-brain neural dynamics during real and virtual social interactions, and the establishment of circuit-based therapy for disorders affecting social functions.
Topics: Mice; Animals; Autism Spectrum Disorder; Prefrontal Cortex; Brain; Nucleus Accumbens; Social Behavior
PubMed: 37612363
DOI: 10.1038/s41380-023-02201-0 -
Cell Feb 2024Human brain development involves an orchestrated, massive neural progenitor expansion while a multi-cellular tissue architecture is established. Continuously expanding...
Human brain development involves an orchestrated, massive neural progenitor expansion while a multi-cellular tissue architecture is established. Continuously expanding organoids can be grown directly from multiple somatic tissues, yet to date, brain organoids can solely be established from pluripotent stem cells. Here, we show that healthy human fetal brain in vitro self-organizes into organoids (FeBOs), phenocopying aspects of in vivo cellular heterogeneity and complex organization. FeBOs can be expanded over long time periods. FeBO growth requires maintenance of tissue integrity, which ensures production of a tissue-like extracellular matrix (ECM) niche, ultimately endowing FeBO expansion. FeBO lines derived from different areas of the central nervous system (CNS), including dorsal and ventral forebrain, preserve their regional identity and allow to probe aspects of positional identity. Using CRISPR-Cas9, we showcase the generation of syngeneic mutant FeBO lines for the study of brain cancer. Taken together, FeBOs constitute a complementary CNS organoid platform.
Topics: Humans; Brain; Central Nervous System; Extracellular Matrix; Organoids; Pluripotent Stem Cells; Prosencephalon; Tissue Culture Techniques; Stem Cells; Morphogenesis
PubMed: 38194967
DOI: 10.1016/j.cell.2023.12.012 -
Nature Reviews. Neuroscience Aug 2023There has been considerable speculation regarding the function of the dentate gyrus (DG) - a subregion of the mammalian hippocampus - in learning and memory. In this... (Review)
Review
There has been considerable speculation regarding the function of the dentate gyrus (DG) - a subregion of the mammalian hippocampus - in learning and memory. In this Perspective article, we compare leading theories of DG function. We note that these theories all critically rely on the generation of distinct patterns of activity in the region to signal differences between experiences and to reduce interference between memories. However, these theories are divided by the roles they attribute to the DG during learning and recall and by the contributions they ascribe to specific inputs or cell types within the DG. These differences influence the information that the DG is thought to impart to downstream structures. We work towards a holistic view of the role of DG in learning and memory by first developing three critical questions to foster a dialogue between the leading theories. We then evaluate the extent to which previous studies address our questions, highlight remaining areas of conflict, and suggest future experiments to bridge these theories.
Topics: Animals; Humans; Dentate Gyrus; Hippocampus; Mental Recall; Learning; Mammals
PubMed: 37316588
DOI: 10.1038/s41583-023-00710-z -
Nature Neuroscience Oct 2023Rapid eye movement (REM) sleep is accompanied by intense cortical activity, underlying its wake-like electroencephalogram. The neural activity inducing REM sleep is...
Rapid eye movement (REM) sleep is accompanied by intense cortical activity, underlying its wake-like electroencephalogram. The neural activity inducing REM sleep is thought to originate from subcortical circuits in brainstem and hypothalamus. However, whether cortical neurons can also trigger REM sleep has remained unknown. Here we show in mice that the medial prefrontal cortex (mPFC) strongly promotes REM sleep. Bidirectional optogenetic manipulations demonstrate that excitatory mPFC neurons promote REM sleep through their projections to the lateral hypothalamus and regulate phasic events, reflected in accelerated electroencephalogram theta oscillations and increased eye movement density during REM sleep. Calcium imaging reveals that the majority of lateral hypothalamus-projecting mPFC neurons are maximally activated during REM sleep and a subpopulation is recruited during phasic theta accelerations. Our results delineate a cortico-hypothalamic circuit for the top-down control of REM sleep and identify a critical role of the mPFC in regulating phasic events during REM sleep.
Topics: Mice; Animals; Sleep, REM; Neurons; Hypothalamus; Prefrontal Cortex; Hypothalamic Area, Lateral; Sleep
PubMed: 37735498
DOI: 10.1038/s41593-023-01398-1 -
Science (New York, N.Y.) Oct 2023The hypothalamus ("hypo" meaning below, and "thalamus" meaning bed) consists of regulatory circuits that support basic life functions that ensure survival. Sitting at... (Review)
Review
The hypothalamus ("hypo" meaning below, and "thalamus" meaning bed) consists of regulatory circuits that support basic life functions that ensure survival. Sitting at the interface between peripheral, environmental, and neural inputs, the hypothalamus integrates these sensory inputs to influence a range of physiologies and behaviors. Unlike the neocortex, in which a stereotyped cytoarchitecture mediates complex functions across a comparatively small number of neuronal fates, the hypothalamus comprises upwards of thousands of distinct cell types that form redundant yet functionally discrete circuits. With single-cell RNA sequencing studies revealing further cellular heterogeneity and modern photonic tools enabling high-resolution dissection of complex circuitry, a new era of hypothalamic mapping has begun. Here, we provide a general overview of mammalian hypothalamic organization, development, and connectivity to help welcome newcomers into this exciting field.
Topics: Animals; Hypothalamus; Mammals; Neocortex; Neurons; Thalamus; Single-Cell Gene Expression Analysis; Neurogenesis
PubMed: 37883552
DOI: 10.1126/science.adh8488 -
Nature Communications Aug 2023Responses of the insular cortex (IC) and amygdala to stimuli of positive and negative valence are altered in patients with anxiety disorders. However, neural coding of...
Responses of the insular cortex (IC) and amygdala to stimuli of positive and negative valence are altered in patients with anxiety disorders. However, neural coding of both anxiety and valence by IC neurons remains unknown. Using fiber photometry recordings in mice, we uncover a selective increase of activity in IC projection neurons of the anterior (aIC), but not posterior (pIC) section, when animals are exploring anxiogenic spaces, and this activity is proportional to the level of anxiety of mice. Neurons in aIC also respond to stimuli of positive and negative valence, and the strength of response to strong negative stimuli is proportional to mice levels of anxiety. Using ex vivo electrophysiology, we characterized the IC connection to the basolateral amygdala (BLA), and employed projection-specific optogenetics to reveal anxiogenic properties of aIC-BLA neurons. Finally, we identified that aIC-BLA neurons are activated in anxiogenic spaces, as well as in response to aversive stimuli, and that both activities are positively correlated. Altogether, we identified a common neurobiological substrate linking negative valence with anxiety-related information and behaviors, which provides a starting point to understand how alterations of these neural populations contribute to psychiatric disorders.
Topics: Animals; Mice; Insular Cortex; Anxiety; Emotions; Anxiety Disorders; Amygdala
PubMed: 37604802
DOI: 10.1038/s41467-023-40517-1 -
Neuron Feb 2024Striatal dopamine (DA) release has long been linked to reward processing, but it remains controversial whether DA release reflects costs or benefits and how these...
Striatal dopamine (DA) release has long been linked to reward processing, but it remains controversial whether DA release reflects costs or benefits and how these signals vary with motivation. Here, we measure DA release in the nucleus accumbens (NAc) and dorsolateral striatum (DLS) while independently varying costs and benefits and apply behavioral economic principles to determine a mouse's level of motivation. We reveal that DA release in both structures incorporates both reward magnitude and sunk cost. Surprisingly, motivation was inversely correlated with reward-evoked DA release. Furthermore, optogenetically evoked DA release was also heavily dependent on sunk cost. Our results reconcile previous disparate findings by demonstrating that striatal DA release simultaneously encodes cost, benefit, and motivation but in distinct manners over different timescales. Future work will be necessary to determine whether the reduction in phasic DA release in highly motivated animals is due to changes in tonic DA levels.
Topics: Mice; Animals; Dopamine; Motivation; Corpus Striatum; Neostriatum; Nucleus Accumbens; Reward
PubMed: 38016471
DOI: 10.1016/j.neuron.2023.10.038 -
Nature Oct 2023The assembly of cortical circuits involves the generation and migration of interneurons from the ventral to the dorsal forebrain, which has been challenging to study at...
The assembly of cortical circuits involves the generation and migration of interneurons from the ventral to the dorsal forebrain, which has been challenging to study at inaccessible stages of late gestation and early postnatal human development. Autism spectrum disorder and other neurodevelopmental disorders (NDDs) have been associated with abnormal cortical interneuron development, but which of these NDD genes affect interneuron generation and migration, and how they mediate these effects remains unknown. We previously developed a platform to study interneuron development and migration in subpallial organoids and forebrain assembloids. Here we integrate assembloids with CRISPR screening to investigate the involvement of 425 NDD genes in human interneuron development. The first screen aimed at interneuron generation revealed 13 candidate genes, including CSDE1 and SMAD4. We subsequently conducted an interneuron migration screen in more than 1,000 forebrain assembloids that identified 33 candidate genes, including cytoskeleton-related genes and the endoplasmic reticulum-related gene LNPK. We discovered that, during interneuron migration, the endoplasmic reticulum is displaced along the leading neuronal branch before nuclear translocation. LNPK deletion interfered with this endoplasmic reticulum displacement and resulted in abnormal migration. These results highlight the power of this CRISPR-assembloid platform to systematically map NDD genes onto human development and reveal disease mechanisms.
Topics: Female; Humans; Infant, Newborn; Pregnancy; Cell Movement; CRISPR-Cas Systems; Gene Editing; Interneurons; Neurodevelopmental Disorders; Organoids; Endoplasmic Reticulum; Prosencephalon; Active Transport, Cell Nucleus
PubMed: 37758944
DOI: 10.1038/s41586-023-06564-w