CA2 hippocampus social

Prairie voles (Microtus ochrogaster) and Syrian, or golden, hamsters (Mesocricetus auratus) are closely related to mice (Mus musculus) and are commonly used in studies of social behavior including social interaction, social memory, and aggression. Hippocampal area CA2 is known to play a key role in these behaviors in mice and responds to social stimuli in rats, but CA2 has yet to be characterized in hamsters or voles, which are also used in studies of social behaviors. Here, we used immunofluorescence to determine whether CA2 could be molecularly identified in tissue from voles and hamsters...

Chronic stress is associated with increased anxiety, cognitive deficits, and post-traumatic stress disorder. Repeated social defeat (RSD) in mice causes long-term stress-sensitization associated with increased microglia activation, monocyte accumulation, and enhanced interleukin (IL)-1 signaling in endothelia and neurons. With stress-sensitization, mice have amplified neuronal, immune, and behavioral responses to acute stress 24 days later. This is clinically relevant as it shares key aspects with post-traumatic stress disorder...

As the most common form of dementia in the world, Alzheimer's disease (AD) is a progressive neurological disorder marked by cognitive and behavioral impairment. According to previous researches, abundant social connections shield against dementia. However, it is still unclear how exactly social interactions benefit cognitive abilities in people with AD and how this process is used to increase their general cognitive performance. In this study, we found that single novel social (SNS) stimulation promoted c-Fos expression, and increased the protein levels of mature ADAM10/17 and sAPPα in the ventral hippocampus (vHPC) of wild-type (WT) mice, which are hippocampal dorsal CA2 (dCA2) neuron activity and vHPC NMDAR dependent...

Prairie voles ( Microtus ochrogaster ) and Syrian, or golden, hamsters ( Mesocricetus auratus ) are closely related to mice ( Mus musculus ) and rats ( Rattus norvegicus , for example) and are commonly used in studies of social behavior including social interaction, social memory, and aggression. The CA2 region of the hippocampus is known to play a key role in social memory and aggression in mice and responds to social stimuli in rats, likely owing to its high expression of oxytocin and vasopressin 1b receptors...

Social memory consists of two processes: the detection of familiar compared with novel conspecifics and the detailed recollection of past social episodes. We investigated the neural bases for these processes using calcium imaging of dorsal CA2 hippocampal pyramidal neurons, known to be important for social memory, during social/spatial encounters with novel conspecifics and familiar littermates. Whereas novel individuals were represented in a low-dimensional geometry that allows for generalization of social identity across different spatial locations and of location across different identities, littermates were represented in a higher-dimensional geometry that supports high-capacity memory storage...

The hippocampal formation, particularly the CA2 subregion, is critical for social memory formation and memory processing, relying on synaptic plasticity-a fundamental mechanism by which synapses strengthen. Given the role of the ubiquitin-proteasome system (UPS) in various nervous system processes, including learning and memory, we were particularly interested in exploring the involvement of RING-type ubiquitin E3 ligases, such as UHRF2 (NIRF), in social behavior and synaptic plasticity. Our results revealed altered social behavior in mice with systemic Uhrf2 knockout, including changes in nest building, tube dominance, and the three-chamber social novelty test...

Oxytocin plays an important role in modulating social recognition memory. However, the direct implication of oxytocin neurons of the paraventricular nucleus of the hypothalamus (PVH) and their downstream hypothalamic targets in regulating short- and long-term forms of social recognition memory has not been fully investigated. In this study, we employed a chemogenetic approach to target the activity of PVH oxytocin neurons in male rats and found that specific silencing of this neuronal population led to an impairment in short- and long-term social recognition memory...

Heterozygous mutations in the dual-specificity tyrosine phosphorylation-regulated kinase 1a (Dyrk1a) gene define a syndromic form of autism spectrum disorder. The synaptic and circuit mechanisms mediating DYRK1A functions in social cognition are unclear. Here, we identify a social experience-sensitive mechanism in hippocampal mossy fiber-parvalbumin interneuron (PV IN) synapses by which DYRK1A recruits feedforward inhibition of CA3 and CA2 to promote social recognition. We employ genetic epistasis logic to identify a cytoskeletal protein, ABLIM3, as a synaptic substrate of DYRK1A...

The cornu ammonis area 2 (CA2) region is essential for social behaviors, especially in social aggression and social memory. Recently, we showed that targeted CA2 stimulation of vasopressin presynaptic fibers from the paraventricular nuclei of hypothalamus strongly enhances social memory in mice. In addition, the CA2 area of the mouse hippocampus receives neuronal inputs from other regions including the septal nuclei, the diagonal bands of Broca, supramammillary nuclei, and median raphe nucleus. However, the functions of these projections have been scarcely investigated...

Parkinson's disease (PD) is a neurodegenerative disease that affects both motor and non-motor functions. Although motor impairment is a prominent clinical sign of PD, additional neurological symptoms may also occur, particularly in the preclinical and prodromal stages. Among these symptoms, social cognitive impairment is common and detrimental. This article aims to review non-motor symptoms in PD patients, focusing on social cognitive deficits. It also examines the specific characteristics of the CA2 region and its involvement in social behavior, highlighting recent advances and perspectives...

The hippocampus is a center of learning, memory, and spatial navigation. This region is divided into the CA1, CA2, and CA3 areas, which are anatomically different from each other. Among these divisions, the CA2 area is unique in terms of functional relevance to sociality. The CA2 area is often manually detected based on the size, shape, and density of neurons in the hippocampal pyramidal cell layer, but this manual segmentation relying on cytoarchitecture is impractical to apply to a large number of samples and dependent on experimenters' proficiency...

Sharp wave ripples (SWRs) are high-frequency synchronization events generated by hippocampal neuronal circuits during various forms of learning and reactivated during memory consolidation and recall. There is mounting evidence that SWRs are essential for storing spatial and social memories in rodents and short-term episodic memories in humans. Sharp wave ripples originate mainly from the hippocampal CA3 and subiculum, and can be transmitted to modulate neuronal activity in cortical and subcortical regions for long-term memory consolidation and behavioral guidance...

Social memories formed in early life, like those for family and unrelated peers, are known to contribute to healthy social interactions throughout life, although how the developing brain supports social memory remains relatively unexplored. The CA2 subregion of the hippocampus is involved in social memory function, but most literature on this subject is restricted to studies of adult rodents. Here, we review the current literature on the embryonic and postnatal development of hippocampal subregion CA2 in mammals, with a focus on the emergence of its unusual molecular and cellular characteristics, including its notably high expression of plasticity-suppressing molecules...

Mice hippocampus contains three prominent subregions, CA1, CA3 and DG and is well regarded as an essential multiple task processor for learning, memory and cognition based on tremendous studies on these three subregions. The narrow region sandwiched between CA1 and CA3 called CA2 has been neglected for a long time. But it raises great attentions recently since this region manifests the indispensable role in social memory. Its unique physical position connecting CA1 and CA3 suggests the potential novel functions besides social memory regulation...

Glycan alterations are associated with aging, neuropsychiatric, and neurodegenerative diseases, although the contributions of specific glycan structures to emotion and cognitive functions remain largely unknown. Here, we used a combination of chemistry and neurobiology to show that 4- O -sulfated chondroitin sulfate (CS) polysaccharides are critical regulators of perineuronal nets (PNNs) and synapse development in the mouse hippocampus, thereby affecting anxiety and cognitive abilities such as social memory...

CA2 is probably the most enigmatic of the hippocampal fields. It is small in size (in humans about 500 μm across the mediolateral axis), and yet, it is involved in important functions, such as in social memory and anxiety. This study offers a glimpse of several significant aspects of the anatomical organization of CA2. We present an overview of the anatomical structure of CA2, imbued in the general organization of the human hippocampal formation. The location and distinctiveness of CA2 is presented in relation with CA3 and CA1, based in a total of 23 human control cases serially sectioned throughout the whole longitudinal axis of the hippocampus, examined every 500 μm in Nissl-stained sections...

Although the hippocampus is crucial for social memory, how social sensory information is combined with contextual information to form episodic social memories remains unknown. Here, we investigated the mechanisms for social sensory information processing using two-photon calcium imaging from hippocampal CA2 pyramidal neurons (PNs)-which are crucial for social memory-in awake head-fixed mice exposed to social and non-social odors. We found that CA2 PNs represent social odors of individual conspecifics and that these representations are refined during associative social odor-reward learning to enhance the discrimination of rewarded compared with unrewarded odors...

Since 1959, the Russian Farm-Fox study has bred foxes to be either tame or, more recently, aggressive, and scientists have used them to gain insight into the brain structures associated with these behavioral features. In mice, hippocampal area CA2 has emerged as one of the essential regulators of social aggression, and so to eventually determine whether we could identify differences in CA2 between tame and aggressive foxes, we first sought to identify CA2 in foxes (Vulpes vulpes). As no clearly defined area of CA2 has been described in species such as cats, dogs, or pigs, it was not at all clear whether CA2 could be identified in foxes...

BACKGROUND AND PURPOSE: High salt (HS) intake has been associated with hypertension and cognitive impairment. It is well-known that angiotensin II (Ang II)-AT1 and prostaglandin E2 (PGE2)-EP1 systems are involved in hypertension and neurotoxicity. However, the involvement of these systems in HS-mediated hypertension and emotional and cognitive impairments remains unclear. EXPERIMENTAL APPROACH: Mice were loaded with HS solution (2% NaCl drinking water) for 12 weeks and blood pressure was monitored...

UNLABELLED: Hippocampal CA2 supports social memory and encodes information about social experiences. Our previous study showed that CA2 place cells responded specifically to social stimuli (Nat Commun, (Alexander et al. 2016)). In addition, a prior study showed that activation of CA2 induces slow gamma rhythms (~ 25-55 Hz) in the hippocampus (Elife, (Alexander 2018)). Together, these results raise the question of whether slow gamma rhythms coordinate CA2 activity during social information processing...