Social migratory connectivity: do birds that socialize in winter breed together?

Researching the complete life cycles of migratory animals is essential for understanding conservation and population dynamics. Many studies focus on the breeding season, but surviving winter is equally important. Living in groups during winter can play a vital role as social connections within groups can provide many benefits such as protection from predators and increased access to resources. However, it is often unknown how social connections change across seasons in migratory animals. We focus on social connections in a migratory bird and ask whether social connections in winter continue during breeding. Golden-crowned sparrows have distinct, stable winter communities which include both site and group fidelity across years: birds almost always rejoin the same social community each year. If these birds have social connectivity across migration, we would expect individuals that associate in winter would also associate together on their breeding grounds. Our small-scale GPS tagging study combined with intensive social behavior data revealed that sparrows in the same tightly-knit winter community migrated to highly disparate locations during summer, showing that social connections in winter do not continue in summer. This suggests that golden-crowned sparrows have entirely separate social structures across seasons and that long-term social memories allow them to reform stable groups each winter.

An interpretation of Cueva de la Huachizca, Santa Clara del Cobre, Michoacan, Mexico

Cueva de la Huachizca is located in the humid forests of the Municipio of Santa Clara del Cobre, Michoacán. During the Postclassic period (1300−1520 ad), Santa Clara del Cobre was a part of the Tarascan Señorio. Ethnographic accounts describe the use of Cueva de la Huachizca as a place of refuge during the Cristero Rebellion (1921−1926). Recent investigations suggest a long history of use including graffiti and inscriptions from the 1800s–1900s and a rock art panel. The panel consists of pecked petroglyphs depicting a man facing an eagle, above a spiral motif. Stylistic analysis of the panel suggests that the rock art was created during pre-Hispanic times, likely by the Postclassic Tarascans. As observed in several regions of Mesoamerica, for the Tarascans, caves were also liminal spaces and had an important role in Postclassic Tarascan cosmology. A ceramic resinera, a pine resin pot, an eagle’s feather, and charcoal were also recovered. The resinera age was estimated by researchers at Archaeomagnetic Services, Geophysics Institute at the National Autonomous University of México-Campus Morelia, Michoacán to between 1921 and 1980. Ethnographic and ethnohistoric accounts describe caves as houses of fertility and rain deities, an idea that while slightly transformed, has survived over 500 years of colonization, and remains in the communities’ social memories. These findings demonstrate the cave’s significance among the descendent communities and Cueva de la Huachizca as an important sacred site.

Fear of a cannibal island: Colonial fear, everyday life, and event landscapes in the Erromango missions of Vanuatu

Archaeological landscapes of colonial encounter were shaped to varying degrees by mutual mistrust, misunderstanding, anxiety, and the inherent terror of frontier violence. In the mission encounters of Island Melanesia, the colonial trope of “cannibalism” added a particular tinge to these fears of the colonized other. Mythologies of cannibalism both repulsed and motivated Christian missionaries who were led to places such as Erromango in the New Hebrides (now Vanuatu). Cannibalism as a practice was rare or even non-existent in these encounters, but it remained part of the European imaginary of the region. Several highly-publicized missionary martyrdoms on Erromango between 1839–1872 remain important to local social memories enacted in place. At the same time, there is a backdrop of relatively peaceful everyday life for missionary families as revealed by the archaeological record of mission houses. The structural and actual violence perpetrated by Europeans in missions and other colonial encounters are historically and currently underemphasized.

Disrupted social memory ensembles in the ventral hippocampus underlie social amnesia in autism-associated Shank3 mutant mice

The ability to remember conspecifics is critical for adaptive cognitive functioning and social communication, and impairments of this ability are hallmarks of autism spectrum disorders (ASDs). Although hippocampal ventral CA1 (vCA1) neurons are known to store social memories, how their activities are coordinated remains unclear. Here we show that vCA1 social memory neurons, characterized by enhanced activity in response to memorized individuals, were preferentially reactivated during sharp-wave ripples (SPW-Rs). Spike sequences of these social replays reflected the temporal orders of neuronal activities within theta cycles during social experiences. In ASD model Shank3 knockout mice, the proportion of social memory neurons was reduced, and neuronal ensemble spike sequences during SPW-Rs were disrupted, which correlated with impaired discriminatory social behavior. These results suggest that SPW-R-mediated sequential reactivation of neuronal ensembles is a canonical mechanism for coordinating hippocampus-dependent social memories and its disruption underlies the pathophysiology of social memory defects associated with ASD.

Complement-associated loss of CA2 inhibitory synapses in the demyelinated hippocampus impairs memory

The complement system is implicated in synapse loss in the MS hippocampus, but the functional consequences of synapse loss remain poorly understood. Here, in post-mortem MS hippocampi with demyelination we find that deposits of the complement component C1q are enriched in the CA2 subfield, are linked to loss of inhibitory synapses and are significantly higher in MS patients with cognitive impairments compared to those with preserved cognitive functions. Using the cuprizone mouse model of demyelination, we corroborated that C1q deposits are highest within the demyelinated dorsal hippocampal CA2 pyramidal layer and co-localized with inhibitory synapses engulfed by microglia/macrophages. In agreement with the loss of inhibitory perisomatic synapses, we found that Schaffer collateral feedforward inhibition but not excitation was impaired in CA2 pyramidal neurons and accompanied by intrinsic changes and a reduced spike output. Finally, consistent with excitability deficits, we show that cuprizone-treated mice exhibit impaired encoding of social memories. Together, our findings identify CA2 as a critical circuit in demyelinated intrahippocampal lesions and memory dysfunctions in MS.

CULTURAL EROSION AND CULTURAL MEMORY IN TAUFIQ RAFAT’S ARRIVAL OF THE MONSOON

Purpose of the study: This study focuses on analyzing and locating the cultural images and the elements which present the idea of cultural erosion, and with the lens of cultural memory evokes the idea of identity, and nostalgia in Taufiq Rafat’s poetry. Methodology: This research is qualitative in design. To explore the concepts of cultural memory and cultural erosion Purposive sampling is used for the selection of the poems. For analysis, textual and descriptive methods of analysis are used. Jan Assmann's (cultural theorist and archaeologist) theory of cultural memory serves as a theoretical framework for this study. Main Findings: From the analysis, it is explored that Rafat’s poetry discerns the concepts of cultural erosion and cultural memory. In the majority of his poems, few dominant images are used repeatedly to strengthen the notion of memory and yearning for the past such as time (clock), the flow of time which is fleeting and nontransient. He not only laments on cultural erosion but also keeps his personal and social memories, traditions, ancient civilizations, rituals, and objects alive so that they could be transferred to the next generations to establish mnemonics. Applications of the study: This research may be beneficial to those studying Anthropology, Culture Studies, History, South Asian Literature, and Sociology. Furthermore, the interpretation of major symbols and images related to the culture, and history which evoke cultural memory, and erosion will pave the way for the deconstruction of symbols in poetry. The novelty of the study: Rafat’s poetry is enriched with natural and romantic images, the depiction of beauty and culture about which many studies are available. The significance of this study lies in the fact that the concept of cultural memory from his poems has been evoked and analyzed.

The Will of the Gods: Patterns of Dream Interpretation in Early Tamil Literature

Societies interpreted their dreams in various ways. While dream interpretation has always been an essential part of medical and philosophical discourse, it was only recently that historians began to show certain interest in writing what is called the cultural history of dream interpretation. In fact, dreams, rituals, myths, social memories and consciously constructed histories all share certain similarities since they engage with the past and are expressed in a narrative form. Dream psychology, therefore, may provide a useful analytical tool for historians who are interested in mapping the mental structure of societies. This article is an attempt to unearth the patterns of dream interpretations by analysing the dream expressions found in Tamil literature up to the twelfth century ad. The social attitude towards dreams in the Sangam literature, early Tamil epics and Bhakti literatures is studied in the sociocultural context of their times. One can presume that the literary language of dreams more or less reflected the contemporary cultural beliefs and social practices.

Complement-associated loss of CA2 inhibitory synapses in the demyelinated hippocampus impairs memory

The complement system is implicated in synapse loss in the MS hippocampus, but the functional consequences of synapse loss remain poorly understood. Here, in post-mortem MS hippocampi with demyelination we find that deposits of the complement component C1q are enriched in the CA2 subfield, are linked to loss of inhibitory synapses and are significantly higher in MS patients with cognitive impairments compared to those with preserved cognitive functions. Using the cuprizone mouse model of demyelination, we corroborated that C1q deposits are highest within the demyelinated dorsal hippocampal CA2 pyramidal layer, and co-localized with inhibitory synapses engulfed by microglia/macrophages. In agreement with the loss of inhibitory perisomatic synapses, we further found that Schaffer collateral feedforward inhibition but not excitation was impaired in CA2 pyramidal neurons and accompanied by a reduced spike output. Ultimately, we show that these electrophysiological changes were associated with an impaired encoding of social memories. Together, our findings identify CA2 as a critical circuit in demyelinated intrahippocampal lesions and memory dysfunctions in MS.