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While recent studies have uncovered dedicated neural pathways mediating the positive control of parenting, the regulation of infant-directed aggression and how it relates to adult-adult aggression is poorly understood. Here we show that urocortin-3 ( Ucn3 )-expressing neurons in the hypothalamic perifornical area (PeFA Ucn3 ) are activated during infant-directed attacks in males and females, but not other behaviors. Functional manipulations of PeFA Ucn3 neurons demonstrate the role of this population in the negative control of parenting in both sexes. PeFA Ucn3 neurons receive input from areas associated with vomeronasal sensing, stress, and parenting, and send projections to hypothalamic and limbic areas. Optogenetic activation of PeFA Ucn3 axon terminals in these regions triggers various aspects of infant-directed agonistic responses, such as neglect, repulsion, and aggression. Thus, PeFA Ucn3 neurons emerge as a dedicated circuit component controlling infant-directed neglect and aggression, providing a new framework to understand the positive and negative regulation of parenting in health and disease.

Spatial transcriptomics can link molecularly described cell types to their anatomical positions and functional roles. Moffitt et al. used a combination of single-cell RNA-sequencing and MERFISH (multiplexed error-robust fluorescence in situ hybridization) to map the identity and location of specific cell types within the mouse preoptic hypothalamus and surrounding areas of the brain (see the Perspective by Tasic and Nicovich). They related these cell types to specific behaviors via gene activity. The approach provides an unbiased description of cell types of the preoptic area, which are important for sleep, thermoregulation, thirst, and social behavior. Science , this issue p. eaau5324 ; see also p. 749 A spatially resolved single-cell transcriptomic study of an essential brain region yields a functionally annotated cell atlas. The hypothalamus controls essential social behaviors and homeostatic functions. However, the cellular architecture of hypothalamic nuclei—including the molecular identity, spatial organization, and function of distinct cell types—is poorly understood. Here, we developed an imaging-based in situ cell-type identification and mapping method and combined it with single-cell RNA-sequencing to create a molecularly annotated and spatially resolved cell atlas of the mouse hypothalamic preoptic region. We profiled ~1 million cells, identified ~70 neuronal populations characterized by distinct neuromodulatory signatures and spatial organizations, and defined specific neuronal populations activated during social behaviors in male and female mice, providing a high-resolution framework for mechanistic investigation of behavior circuits. The approach described opens a new avenue for the construction of cell atlases in diverse tissues and organisms.

The positive effect of stress on memory formation involves glucocorticoid receptors, but is otherwise not well understood. This article reports that stressful memory consolidation in rats involves the activation of a nongenomic molecular cascade downstream of hippocampal glucocorticoid receptors that overlaps with the BDNF-TrkB signaling pathway. Emotionally important events are well remembered. Although memories of emotional experiences are known to be mediated and modulated by stress hormones such as glucocorticoids, little is known about the underlying molecular mechanisms. We found that the hippocampal glucocorticoid receptors that are critically engaged during the formation of long-term inhibitory avoidance memory in rats were coupled to the activation of CaMKIIα, TrkB, ERK, Akt, PLCγ and CREB, as well as a to a substantial induction of Arc and synaptic GluA1. Most of these changes, which are initiated by a nongenomic effect of glucocorticoid receptors, were also downstream of the activation of brain-derived neurotrophic factor (BDNF). Hippocampal administration of BDNF, but not of other neurotrophins, selectively rescued both the amnesia and the molecular impairments produced by glucocorticoid receptor inhibition. Thus, glucocorticoid receptors mediate long-term memory formation by recruiting the CaMKIIα-BDNF-CREB–dependent neural plasticity pathways.

Highly multiplexed single-molecule FISH has emerged as a promising approach to spatially resolved single-cell transcriptomics because of its ability to directly image and profile numerous RNA species in their native cellular context. However, background—from off-target binding of FISH probes and cellular autofluorescence—can become limiting in a number of important applications, such as increasing the degree of multiplexing, imaging shorter RNAs, and imaging tissue samples. Here, we developed a sample clearing approach for FISH measurements. We identified off-target binding of FISH probes to cellular components other than RNA, such as proteins, as a major source of background. To remove this source of background, we embedded samples in polyacrylamide, anchored RNAs to this polyacrylamide matrix, and cleared cellular proteins and lipids, which are also sources of autofluorescence. To demonstrate the efficacy of this approach, we measured the copy number of 130 RNA species in cleared samples using multiplexed error-robust FISH (MERFISH). We observed a reduction both in the background because of off-target probe binding and in the cellular autofluorescence without detectable loss in RNA. This process led to an improved detection efficiency and detection limit of MERFISH, and an increased measurement throughput via extension of MERFISH into four color channels. We further demonstrated MERFISH measurements of complex tissue samples from the mouse brain using this matrix-imprinting and -clearing approach. We envision that this method will improve the performance of a wide range of in situ hybridization-based techniques in both cell culture and tissues.

Infant avoidance and aggression are promoted by activation of the Urocortin-3 expressing neurons of the perifornical area of hypothalamus (PeFA Ucn3 ) in male and female mice. PeFA Ucn3 neurons have been implicated in stress, and stress is known to reduce maternal behavior. We asked how chronic restraint stress (CRS) affects infant-directed behavior in virgin and lactating females and what role PeFA Ucn3 neurons play in this process. Here we show that infant-directed behavior increases activity in the PeFA Ucn3 neurons in virgin and lactating females. Chemogenetic inhibition of PeFA Ucn3 neurons facilitates pup retrieval in virgin females. CRS reduces pup retrieval in virgin females and increases activity of PeFA Ucn3 neurons, while CRS does not affect maternal behavior in lactating females. Inhibition of PeFA Ucn3 neurons blocks stress-induced deficits in pup-directed behavior in virgin females. Together, these data illustrate the critical role for PeFA Ucn3 neuronal activity in mediating the impact of chronic stress on female infant-directed behavior.

We report that, in the rat, administering insulin-like growth factor II (IGF-II, also known as IGF2) significantly enhances memory retention and prevents forgetting. Inhibitory avoidance learning leads to an increase in hippocampal expression of IGF-II, which requires the transcription factor CCAAT enhancer binding protein β and is essential for memory consolidation. Furthermore, injections of recombinant IGF-II into the hippocampus after either training or memory retrieval significantly enhance memory retention and prevent forgetting. To be effective, IGF-II needs to be administered within a sensitive period of memory consolidation. IGF-II-dependent memory enhancement requires IGF-II receptors, new protein synthesis, the function of activity-regulated cytoskeletal-associated protein and glycogen-synthase kinase 3 (GSK3). Moreover, it correlates with a significant activation of synaptic GSK3β and increased expression of GluR1 (also known as GRIA1) α-amino-3-hydroxy-5-methyl-4-isoxasolepropionic acid receptor subunits. In hippocampal slices, IGF-II promotes IGF-II receptor-dependent, persistent long-term potentiation after weak synaptic stimulation. Thus, IGF-II may represent a novel target for cognitive enhancement therapies. Growth-factor target for memory drugs An understanding of the mechanisms of memory enhancement is vital for broadening our knowledge of memory processes, as well as for potential clinical applications. Yet very little is known about it. Experiments in rats now show that the administration of insulin-like growth factor II (IGF-II), a protein typically implicated in somatic tissue growth and repair, significantly enhances memory retention, promotes the memory proxy known as long-term potentiation and prevents forgetting. IGF-II acts by initiating a network of signalling cascades that can lead to synaptic potentiation and are most effective within a short time frame immediately following learning. IGF-II is therefore a potential target for modulating cognitive enhancement. After learning, memories are strengthened through a process called 'consolidation', which requires new gene and protein expression, rendering new information less vulnerable to disruption. Several transcription factor families are involved in this process, but many of the relevant downstream targets are unknown. Here, IGF-II, a protein typically implicated in somatic tissue growth and repair, is identified as an essential factor in memory retention. IGF-II initiates its own network of signalling cascades that can lead to synaptic potentiation and are most effective within a short time frame immediately after learning. Thus, IGF-II represents an endogenous target for potentially modulating cognitive enhancement.

Emotionally important events are well remembered. Although memories of emotional experiences are known to be mediated and modulated by stress hormones such as glucocorticoids, little is known about the underlying molecular mechanisms. We found that the hippocampal glucocorticoid receptors that are critically engaged during the formation of long-term inhibitory avoidance memory in rats were coupled to the activation of CaMKIIα, TrkB, ERK, Akt, PLCγ and CREB, as well as a to a substantial induction of Arc and synaptic GluA1. Most of these changes, which are initiated by a nongenomic effect of glucocorticoid receptors, were also downstream of the activation of brain-derived neurotrophic factor (BDNF). Hippocampal administration of BDNF, but not of other neurotrophins, selectively rescued both the amnesia and the molecular impairments produced by glucocorticoid receptor inhibition. Thus, glucocorticoid receptors mediate long-term memory formation by recruiting the CaMKIIα-BDNF-CREB-dependent neural plasticity pathways.

While recent studies have uncovered dedicated neural pathways mediating the positive control of parenting, the regulation of infant-directed aggression and how it relates to adult-adult aggression is poorly understood. Here we show that urocortin-3 (Ucn3)-expressing neurons in the hypothalamic perifornical area (PeFAUcn3) are activated during infant-directed attacks in males and females, but not other behaviors. Functional manipulations of PeFAUcn3 neurons demonstrate the role of this population in the negative control of parenting in both sexes. PeFAUcn3 neurons receive input from areas associated with vomeronasal sensing, stress, and parenting, and send projections to hypothalamic and limbic areas. Optogenetic activation of PeFAUcn3 axon terminals in these regions triggers various aspects of infant-directed agonistic responses, such as neglect, repulsion and aggression. Thus, PeFAUcn3 neurons emerge as a dedicated circuit component controlling infant-directed neglect and aggression, providing a new framework to understand the positive and negative regulation of parenting in health and disease.

Mammals invest considerable resources in protecting and nurturing young offspring. However, under certain physiological and environmental conditions, animals neglect or attack young conspecifics. Males in some species attack unfamiliar infants to gain reproductive advantage and females kill or neglect their young during stressful circumstances such as food shortage or threat of predation. In humans, stress is a risk factor in both sexes for peripartum disorders and associated impairments in parent-infant interactions. While recent studies have uncovered dedicated neural pathways mediating the positive control of parenting, the regulation of infant-directed neglect and aggression and the relationship between these behaviours and stress are poorly understood. Here we show that urocortin-3 (Ucn3)-expressing neurons in the perifornical area (PeFAUcn3) of the hypothalamus are activated during infant-directed attacks in males and females, but not other forms of aggression. Opto- and chemogenetic manipulations of PeFAUcn3 neurons demonstrate the role of this neuronal population in the negative control of parenting in both males and females. PeFAUcn3 neurons receive input from areas associated with vomeronasal sensing, stress, and parenting, and send major projections to the ventromedial hypothalamus (VMH), ventral lateral septum (LSv) and amygdalohippocampal area (AHi). Optogenetic activation of PeFAUcn3 axon terminals in these regions triggers different aspects of infant-directed agonistic responses, such as neglect and aggression. Thus, PeFAUcn3 neurons emerge as a critical hub for the expression of infant-directed neglect and aggression, providing a new framework to examine the positive and negative regulation of parenting.