搜索结果：Brain, behavior and evolution

The evolutionary expansion of the mammalian neocortex-especially in primates-underpins the emergence of advanced cognitive abilities. This process involved not only increased cortical surface area and neuronal output but also enhanced structural adaptations, such as cortical folding and glial morphological complexity. In this review, we examine the central roles of radial glia (RG) and astrocytes in driving neocortical expansion and evolution. We highlight the emergence of primate- and human-specific genes, which contribute to enhanced RG proliferation and neurogenesis in these species. We further explore how epigenetic regulation and dynamic chromatin architecture modulate RG behavior across species. At the cellular level, we discuss how morphological features-particularly the basal processes and specialized protrusions of RG-facilitate access to diverse extrinsic signals, promoting proliferative capacity and cortical complexity. We then turn to cortical folding, focusing on the role of astrocytes, and the functional relevance of folds in supporting brain homeostasis. Finally, we address astrocyte diversity, development, and evolutionary adaptation, with special emphasis on sex differences and primate-specific features. Comparative transcriptomic and morphological studies reveal that human astrocytes exhibit unique molecular signatures, expanded metabolic capacity, and higher morphological complexity. Together, these insights underscore the multifaceted contributions of RG and astrocytes to the evolutionary elaboration of the neocortex. They further provide a framework for understanding how cellular innovations shaped the modern primate brain in general, and human brain specifically.

Intranasal administration, as a non-invasive brain-targeted delivery strategy, offers a promising approach for the treatment of central nervous system disorders, particularly depression. Traditional oral or intravenous drug delivery is often limited by the restrictive permeability of the blood-brain barrier and the hepatic first-pass effect, which hinder effective drug accumulation in the brain. In contrast, the intranasal route leverages the olfactory and trigeminal neural pathways to enable direct drug transport from the nasal cavity to the brain, effectively bypassing the blood-brain barrier and significantly enhancing brain drug bioavailability. This article systematically reviews the research progress of intranasal drug delivery in the treatment of depression-like behaviors, highlighting the technological evolution of various drug-loading modalities, including solutions, gels, nanoparticles, in situ gels, and cell membrane biomimetic carriers, and analyzes their differences in nasal mucosal retention time, mucus penetration ability, and brain-targeting efficiency. Furthermore, it elaborates on the multiple antidepressant mechanisms of intranasal materials, such as regulating neurotransmitter systems (e.g., 5-Hydroxytryptamine, Dopamine, Glutamate), inhibiting neuroinflammation (e.g., microglial activation, inflammatory factor release), enhancing neuroplasticity (e.g., promoting hippocampal neurogenesis and synapse formation), and modulating the gut microbiota-gut-brain axis. Simultaneously, the article integrates data from multiple clinical trials, focusing on evaluating the efficacy and safety of intranasal formulations such as esketamine in treatment-resistant depression, highlighting their advantages of rapid onset and high response rates, and discussing management strategies for adverse reactions such as dose individualization, local irritation, and dissociative symptoms. Addressing current technical bottlenecks, such as uneven drug absorption due to nasal physiological differences, challenges in the large-scale production of nanocarriers, and insufficient long-term safety evidence, the article proposes that future research should focus on the development of intelligent responsive nanocarriers, the construction of multimodal synergistic treatment systems, the design of personalized medication regimens guided by precision medicine, and the coordinated advancement of real-world research and regulatory standards. This review aims to provide comprehensive theoretical support and development directions for the clinical translation of intranasal drug delivery in the field of depression treatment.

Brain lateralization is a longstanding feature of the primate lineage and is often considered distinctive of the human lineage, particularly in relation to lateralized behaviors. However, little is known about the macroevolutionary dynamics of asymmetric endocranial shape across fossil and extant catarrhines. Here we apply three dimensional geometric morphometrics to a comparative sample of extant apes, humans, and fossil hominins to investigate patterns, rates, and directions of brain shape lateralization under an explicit phylogenetic framework. We analyzed 161 cranial endocasts representing 81 extant and extinct Catarrhine species, using high-resolution geometric morphometrics. We focus on endocast shape lateralization as an evolutionary component of endocranial morphology rather than on individual level hemispheric differences. Rates of asymmetric shape change are quantified across lineages by using Phylogenetic Ridge Regression (RRphylo) to map evolutionary rates of endocast shape lateralization directly onto the cortical surface. Our results show that hominins exhibit distinctly higher rates of asymmetric endocranial shape evolution compared with non human apes, with particularly pronounced changes observed along the lineage leading to modern humans. These changes are not explained by single-side brain size variation and are spatially concentrated in specific regions of the endocranial surface. The patterns we identified reflect macroevolutionary modifications of endocranial shape and do not constitute direct evidence of hemispheric functional specialization. Nevertheless, the observed evolutionary dynamics are consistent with broader scenarios involving increasing structural reorganization of the human brain during hominin evolution. These findings provide a quantitative framework for investigating the evolutionary history of endocranial asymmetry and its potential biological correlates while maintaining a clear distinction between morphological evidence and functional interpretation.

Research on the relationship between the evolution of ontogenetic locomotor milestones and the emergence of advanced cognition in early hominins is reviewed and discussed from an evo-devo perspective that incorporates theoretical underpinnings from the Extended Evolutionary Synthesis (EES). Comparative ontogenetic data from chimpanzee and human infants shed light on likely derivations in hominin locomotor milestones, their effect on the emergence of habitual bipedalism, and the latter's probable contribution(s) to cognitive evolution. Human babies' locomotor milestone of crawling on hands and knees is hypothesized to have been derived during hominin evolution in place of a knuckle-walking developmental stage that likely existed in the apelike predecessors of the earliest hominins. A review of comparative research suggests that evolutionary modifications in crawling, sitting, and pointing in addition to selection for bipedalism, contributed to the progressive evolution of both locomotion and advanced cognition in hominins. Comparisons of the ontogenetic development of locomotor stages in chimpanzee and human infants suggest that locomotor evolution and the emergence of advanced cognition were deeply intertwined during hominin evolution.

The brainstem connects the forebrain to the spinal cord. It consists of three layers, the ventral basis, the intermediate tegmentum, and the dorsal tectum. Caudo-rostrally, the brainstem is divided into the medulla oblongata or myelencephalon, the metencephalon, and the mesencephalon. The tegmentum is the most conserved part of the brainstem and contains the motor and sensory nuclei of cranial nerves (CN) III-XII. They are arranged in a mediolateral direction, and, unlike the spinal cord, their afferent and efferent fibers are not macroscopically separated. The tegmental reticular formation, the brainstem core, has a lattice structure with manifold longitudinal and transverse fibers and stacked neurons. Its architecture provides maximum convergence and divergence of intrinsic and ascending/descending information from the spinal cord and forebrain. It coordinates brainstem-based vital functions, and its integrity is essential for arousal, consciousness, and goal-directed behavior. Its small aminergic and cholinergic telencephalic projection nuclei have a profound impact on mood, motivation, and cognition. Human telencephalic evolution manifests in volume increases of the cerebral crura, pons, cerebellar hemispheres, olives, pyramidal tract, and medial lemniscus. However, the spatial constraints of the posterior fossa limited the proportional expansion of the brainstem during human telencephalic evolution, rendering this evolutionarily conserved structure increasingly vulnerable to malfunction and disease.

How the brains of domestic animals evolved under domestication remains poorly understood. We quantified brain shape variation in domestic dogs (n = 203, 111 breeds) and wolves (n = 40) using endocast-based 3D geometric morphometrics. Size, shape, and morphological integration were assessed on the whole brain, and in six morphofunctional subregions. Results demonstrate that domestication and artificial selection significantly restructured brain form and morphological integration patterns in dogs, reflecting mosaic evolution across brain subregions. Dogs exhibit a three-fold increase in brain shape variation relative to wolves, as well as expanded frontal lobes and areas putatively associated with social interaction behavior-these regions are also larger in cooperative vs. independent breeds. Morphological integration is higher in dogs than wolves, and in modern breeds compared to ancient breeds. Thus, rather than constrain, integration appears to facilitate neuroanatomical evolvability under domestication and breeding selection. Ancient dog breeds retain more wolf-like neuroanatomy. Breed function is a poor predictor of brain shape, but brain integration restructures according to breed function, with working breeds displaying the highest integration. These findings reveal the profound impact of domestication on neuroanatomical evolution, emphasizing neuroanatomical features linked to social behavior, and challenging prevailing assumptions about the role of structural integration on evolvability.

Tacaribe virus (TCRV), a New World arenavirus, is associated with neotropical frugivorous bats, particularly Artibeus spp., and is considered to have zoonotic potential. Here, we report the detection of TCRV in multiple biological compartments of a Molossus molossus (velvety free-tailed bat), an insectivorous species commonly found in Brazilian urban ecosystems. Brain tissues negative for rabies were subjected to high-throughput RNA sequencing, revealing a diverse array of viral taxa, including partial L and S segments of TCRV with respective genome coverages of 68.2% and 65.6%. These sequences shared 90% nucleotide identity and 94% amino acid identity with TCRV reference strains. Phylogenetic reconstruction grouped the newly identified TCRV sequences and the TCRV strain A354 (isolated from a Brazilian Artibeus planirostris bat) within a clade that also includes Tietê mammarenavirus strains (Brazilian Carollia perspicillata bat), both of which are genetically divergent members of the Arenaviridae family. The detection of TCRV in M. molossus may indicate previously unrecognized circulation of this virus in insectivorous bats, expanding our understanding of its tissue tropism and host range. This finding is particularly significant given the synanthropic behavior of M. molossus bats and its potential implications for TCRV evolution. Moreover, our results highlight the critical role of untargeted high-throughput sequencing in uncovering overlooked viral diversity, enabling the detection of unexpected pathogens in non-traditional hosts and tissues. While TCRV remains poorly characterized in terms of human pathogenicity, continued surveillance is warranted to assess potential spillover risks. Understanding which animals carry viruses is key to predicting and preventing disease spread. Here, we report the first detection of Tacaribe virus (TCRV), previously found only in fruit-eating bats, in multiple biological compartments, including the brain, of Molossus molossus, an insect-eating bat common in urban areas of Brazil. This finding expands the known range of both the virus and its possible hosts. By confirming this unexpected host-virus association using original tissue samples, our study provides new insights into how TCRV may circulate in nature. While TCRV is not currently considered a major threat to humans, its detection in a new bat species raises important questions about its transmission, evolution, and potential health impacts. These results emphasize the importance of monitoring diverse bat species, including those not traditionally linked to specific viruses, to better assess emerging virus risks in changing environments.

Background and Objectives: Brain metastases frequently evolve over time in multiple waves, especially in patients with prolonged survival. Despite repeated imaging and targeted therapies, lesion-level continuity is fragmented in clinical practice, as follow-up is typically limited to pairwise MRI comparisons. The aim of the study is to assess the ability of routine narrative MRI follow-up reports to preserve longitudinal lesion identity and to reconstruct a coherent trajectory of disease evolution. Materials and Methods: We conducted a single-center, retrospective, observational study of all brain MRI examinations performed between June 2024 and June 2025 (n = 731 scans, 616 patients). All imaging reviews and longitudinal lesion tracking were performed by one board-certified neuroradiologist. Adult patients with confirmed brain metastases and at least three MRI examinations (including external studies) were included. We assessed the concordance of routine narrative MRI follow-up reports against a longitudinal review of all available MRIs and treatment timelines, which served as the reference standard. Lesion identity was considered preserved when reports explicitly recognized and linked lesions across time points, and lost when identity was omitted or ambiguous in at least one report. Results: The final cohort comprised 73 patients (477 tracked lesions). More than half of monitored lesions disappeared (42.9%) or evolved into post-treatment sequelae (9.9%), and were omitted from narrative reports, limiting retrospective recognition without prior imaging. The ability of routine reports to preserve lesion identity declined as cases became more complex. Concordance was higher in uniform evolution patterns (≈60%) but dropped to 18.2% in mixed evolution. A similar decline was seen with sequential metastatic waves, defined as new metastases appearing at distinct time points: 65.2% (1 wave), 46.7% (2 waves), 18.2% (3 waves), and complete loss of continuity when >3 waves occurred. Conclusions: Routine narrative MRI follow-up reports generally provide adequate information in simple cases with uniform lesion behavior, but tend to lose critical details as disease trajectories become more complex, particularly in heterogeneous or multi-wave disease. Even when individual lesions are identified across examinations, documentation remains fragmented and reflects only a snapshot of the disease course rather than an integrated longitudinal perspective. These findings highlight a critical vulnerability in current follow-up practices. Improving lesion-level continuity, potentially through AI-assisted tools, may enhance the accuracy, consistency, and clinical utility of MRI surveillance in patients with brain metastases.

The Developing Belief Network is a global research collaborative studying religious development in diverse social-cultural settings, with a focus on the intersection of cognitive mechanisms and cultural beliefs and practices in early and middle childhood. The current manuscript describes the study protocol for the network's second wave of data collection, which aims to further explore the development and diversity of religious cognition and behavior using a multi-time point approach. This protocol is designed to investigate three key research questions-how children represent and reason about religious and supernatural agents, how children represent and reason about religion as an aspect of social identity, and how religious and supernatural beliefs are transmitted within and between generations-via a set of eight tasks for children between the ages of 5 and 13 years and a survey completed by their parents/caregivers. This study is being conducted in 41 distinct cultural-religious settings, spanning 16 countries and 12 written languages. In this manuscript, we provide detailed descriptions of all elements of this study protocol, and give a brief overview of the ways in which this protocol has been adapted for use in diverse religious communities. As one example of how this protocol has been implemented outside of the United States, we present Arabic- and English-language study materials for children being raised in one of the following religious traditions in Lebanon: the Druze faith, Maronite Christianity, Orthodox Christianity, Shia Islam, or Sunni Islam. We end with reflections on the challenges of developing and implementing large-scale, multi-site, multi-time point studies of child development; our approach to navigating these challenges; and our suggestions for how future researchers might learn from our experiences and build on the work presented here.

Humans display larger and more complex parietal lobes, when compared with other primates. The superior parietal lobule is a region still poorly known in terms of comparative and evolutionary neuroanatomy, although at least its medial region, the precuneus, is apparently expanded in our species. In this article, I review 20 years of personal research on the morphology and evolution of this cortical element. The precuneus is particularly variable among adult humans, mostly in its dorsal and anterior areas. This large individual variability seems already settled at birth. During aging, this cortical region is particularly sensitive to atrophy and neurodegeneration. Its ventral areas are embedded in a complicated topological environment, suggesting spatial, metabolic, and vascular constraints. Human and nonhuman primates share a similar organization of the superior parietal lobule, although with different proportions. Even when compared with extinct hominids, the precuneus in modern humans looks more expanded. These changes are expected to be associated with some cognitive variations, possibly involving visuospatial integration, body cognition, mental imaging, and self-construction.

Diagnoses of eating disorders often evolve over time, yet research in China is scarce. Thus, this study aims to explore the evolution of eating disorder diagnoses and symptom development characteristics in the Chinese cultural context through high-quality retrospective examination, and to analyze risk factors for common symptom development. A retrospective analysis of patients diagnosed with eating disorders from 2019 to 2024 with a disease course exceeding two years. Data on age at onset, BMI, symptom onset, and other relevant variables were collected by reviewing outpatient medical records to determine longitudinal symptom progression and diagnostic shifts. A multifactorial cox proportional hazards model was constructed incorporating variables such as age of onset, sex, family history, self-harm, and amenorrhea to predict binge eating in restrictive eating disorder. Among 128 outpatients with eating disorders, 50.8 % experienced diagnostic shifts, predominantly from restrictive anorexia to binge-purge types, with complex symptom evolution in the majority. Survival analysis indicates that self-harm behavior significantly affects survival time compared to no self-harm (HR = 1.534, 95 %CI = 1.012-2.325, p = 0.044), and amenorrhea significantly affects survival time compared to no amenorrhea (HR = 0.565, 95 % CI = 0.373-0.855, p = 0.007). In the Chinese cultural context, diagnostic shifts and symptom overlaps across eating disorder subtypes are observed, potentially indicating a natural progression of clinical phenomena. Assessment of self-harm and amenorrhea is crucial in the early diagnosis and treatment of eating disorders, particularly in patients with restrictive eating behaviors.

Evolution of novel behavior is reflected in changes in sensory investment or integration, but the exact nature of these changes is often unclear. The Neotropical butterfly tribe, Heliconiini, offer an attractive system for studying how behavioral evolution is facilitated by changes in the neural system. Within the Heliconiini tribe, the genus Heliconius possess fourfold larger mushroom bodies, the insect learning and memory center, than closely related Heliconiini. Mushroom body expansion in Heliconius co-occurred with a dietary innovation, and is associated with systematic spatial foraging and extended lifespan. Heliconius' foraging relies on visual scene memories and, indeed, Heliconius have stable visual long-term memory, and evidence of visual specialization in the mushroom bodies. Here, we explore how vision-specific neuroanatomical and behavioral enhancement in Heliconius impacts sensory pathways upstream of the mushroom bodies by assessing investment across the eyes, sensory neuropils, and projection pathways. Despite evidence of refinement in visually based behavior, we found no increased investment in visual structures, brain areas, or pathways. This suggests that the rapid expansion of the Heliconius mushroom body occurred in a context of conserved detection and processing of visual cues, and that a localized shift within integrative brain centers facilitated the evolution of Heliconius' novel behaviors.

The macaque genus includes 25 species with diverse social systems, ranging from low to high social tolerance grades. Such interspecific behavioral variability provides a unique model to tackle the evolutionary foundation of primate social brain. Yet, the neuroanatomical correlates of these social tolerance grades remain unknown. To address this question, we expressed social tolerance grades within a novel cognitive framework and analyzed post-mortem structural scans from 12 macaque species. Our results show that amygdala volume is a subcortical predictor of macaques' social tolerance, with high tolerance species exhibiting larger amygdala than low tolerance ones. We further investigated the developmental trajectory of amygdala across social grades and found that intolerant species showed a gradual increase in relative amygdala volume across the lifespan. Unexpectedly, tolerant species exhibited a decrease in relative amygdala volume across the lifespan, contrasting with the age-related increase observed in intolerant species-a developmental pattern previously undescribed in primates. Taken together, these findings provide valuable insights into the cognitive, neuroanatomical, and evolutionary basis of primates' social behaviors. Macaque monkeys live under a variety of social regimes. Some species flourish within highly structured, hierarchical societies, while others navigate more tolerant yet less predictable social networks. Primatologists have categorised these social differences, including how often reconciliation occurs after conflicts, into four levels of social tolerance. However, the neuronal mechanisms underlying these social variations remain poorly understood. Closely related species offer a natural laboratory for studying the social brain in primates. To investigate how neural networks may have evolved in response to differing social challenges, Silvère et al. analysed 43 brain scans from 12 macaque species. All data were gathered from animals that had died of natural or accidental causes The scans showed that the relative size of a species’ amygdala – a brain region involved in emotional responses, decision-making, and memory – correlates with its level of social tolerance. For example, low-tolerance species are born with a smaller amygdala, which grows larger with age. Conversely, in more socially tolerant species, the amygdala decreases in size as they age, contrasting with findings in other primates, including humans. These findings imply that living in a more tolerant social environment could impose greater cognitive demands on the brain, with the amygdala possibly playing a part in complex social cognition. In contrast, the volume of a brain region called the hippocampus revealed more variable differences across social grades among macaques, with a more significant effect observed only in individuals aged between 13 and 18 years. Additionally, differences in hippocampal volume also varied among monkeys living in different areas, supporting the idea that certain regions contribute to social cognitive processes in tolerant species, particularly during developmental phases linked to social maturation. Exploring natural variation in brain evolution and function opens new avenues for primate neuroscience. A more extensive comparative analysis across all living primate species could further clarify evolutionary pathways. Moreover, identifying neural networks that are either evolutionarily conserved or highly variable may help shape new research directions aimed at understanding the biological basis of neurodivergence.

Neuroethologists study many non-model animals. The development of techniques for precise and standardized histological brain analysis is key for understanding neural mechanisms across species. Here we present a novel cost-effective approach to generate species-specific brain matrices for precise and reproducible trimming, blocking, and sectioning of brain tissue. To produce the matrix, we took high-quality photographs of two male CP brains and then used the open-source 3D graphics suite Blender and its inexpensive photogrammetry plug-in SnapMesh to generate the 3D brain surface model. The brain matrix was then modeled in Blender, and 3D printed. Using this approach, we produced the first 3D brain surface model and brain matrix for Seba's short-tailed fruit bat Carollia perspicillata, CP, and assessed its quality using CP brains. Our brain matrix facilitates and standardizes trimming or blocking of brains, providing consistent access to brain regions of CP in the sagittal and coronal planes. This workflow should be suitable for most vertebrate brains. Photogrammetry offers a viable, inexpensive alternative to 3D- or CT-scanners. Our workflow is not only cheaper than alternatives, but does not require blocking the brain during preparation of the 3D surface model, resulting in no tissue loss. The cost-effectiveness and the tissue-preserving features will benefit researchers globally, particularly those with limited financial means and/or few valuable specimens. By providing an accessible, customizable and reproducible workflow, our study represents a significant step toward democratizing advanced neuroscience across diverse species.

Star-nosed moles are renowned as the fastest foragers among mammals, able to identify and eat small prey in less than a quarter of a second. This ability stems in part from the mole's extraordinary mechanosensory star which has been the focus of many investigations. However, fast eating also requires a specialized motor system and associated structures. Here, the mole's unusual incisors are explored as a key adaptation for efficient foraging. High-speed videos of foraging moles, including microscopic views at 1,000 frames per second, were used to measure prey handling time and tooth movements. Scanning electron microscopy was used to assess tooth structure. Specimens from Cornell Museum of Vertebrates were examined with light microscopy. Data from previous investigations were compared to the present results. A mole with worn front teeth was discovered, and this specimen often failed to secure small prey efficiently, thus doubling the mole's handling time compared to normal specimens. The manner in which the worn teeth failed suggested the mole's normal incisors are analogous to a specific type of man-made surgical forceps - so-called Yaşargil tumor forceps. The results reveal an example of serendipitous biomimicry by human surgeons in designing soft tissue forceps, highlight the importance of motor specializations in the star-nosed mole's fast foraging ability, and suggest some of the specific anatomical specialization that are the result of selection on the key variables (space clearance rate and handling time) in Holling's pioneering foraging theory equation.

Wet dog shake (WDS) is a motion in mammals and birds, consisting in vigorous and rapid rotations of the head and trunk around the spinal axis, which allows them to dry themselves. WDS requires fine balance control. To date, motor control in WDS has not been studied. Here, for the first time, we investigated the trunk and limbs muscle EMG activity and correlated it with the kinematics of body movement and ground reactions force during WDS in rats. Strict reciprocity was revealed between the forelimb muscle on the right and left sides despite bipedal hindlimb position. Reciprocal activity was observed between the lumbar and the thoracic segments. The hindlimb muscle activity exhibited two distinct muscle synergies with strict reciprocity and atypical co-activity of flexors and extensors, which were previously observed in paw shaking behavior. These two synergies correlate with the two muscle groups of the pelvic fins of fish. The absence of typical postural responses of the hindlimb was revealed. (1) It is likely that WDS and paw shaking share a common nervous control. (2) The absence of typical postural responses may indicate that body balance in WDS is maintained by perfectly matched frequency and strength of the trunk muscle contractions. (3) In the hypothesis about the origin of WDS, based on the revealed characteristics, we compare it with the S-start response behavior in fish.

Neuron size varies significantly over evolution, contributing to diverse nervous systems of variable complexity, while aberrant neuron size is associated with neurodevelopmental and degenerative diseases. How do neuron cell body and neurite size and organization impact nervous system development and function? To systematically study the effects of neuron size on the vertebrate nervous system, we characterized triploid Xenopus tadpoles, which possess a 1.5-fold increase in genome size compared with diploids. Triploid neurons displayed a scaling increase in total volume and a superscaling increase in membrane surface area. Imaging, flow cytometry, and RNA sequencing analyses revealed that triploid brains were morphologically and transcriptionally similar to diploid brains but less proliferative, containing fewer neurons and displaying increased global activity. Interestingly, physiological differences at the neuron and nervous system levels affected swimming behavior in tadpoles. Our findings thus establish a framework to link genome size, neuron size, and nervous system development and function in vertebrates.

Neuroplasticity enables the brain to reorganize in response to developmental change and experience, thereby supporting behavioral flexibility. In insects, both age and experience are known to influence neural structure, but how these factors differ between the sexes remains largely unexplored. Here, using micro-CT scanning, we quantify volumetric plasticity across eight brain regions in the orchid bee Euglossa dilemma, a facultatively social species with pronounced sexual dimorphism in behavior. We show that neuroplasticity follows sex- and region-specific trajectories that map onto the distinct reproductive behaviors exhibited by male and female bees. Consistent with other insect species, both sexes exhibited neuroplasticity in the mushroom bodies but only males showed an experience-dependent expansion, which we attribute to the navigational demands of reproductive behaviors. This was further supported by the expansion of olfactory and visual processing centers associated with the sensory demands of perfume collection and courtship display. Females, in contrast, undergo an exclusively age-dependent volumetric expansion of the mushroom bodies, an experience-dependent expansion of the antennal lobes, and a reduction of the visual neuropils. These patterns of plasticity correlate with female nesting behavior and may reveal potential energy trade-offs during reproduction. Our findings provide the first evidence of exclusively age-driven neuroplasticity in the mushroom bodies of social female bees and establish E. dilemma as a valuable comparative model for studying the evolution of brain plasticity and behavioral adaptation in social insects.

Baird's beaked whale, a member of the family Ziphiidae, is one of the largest odontocetes, second only in body mass to the sperm whale. Baird's beaked whales are known for their ability to dive to exceptional depths; however, this behavior makes them difficult to observe in their natural habitat and has resulted in major gaps in our understanding of the species. To address part of this gap, this study provides a comprehensive description of the Baird's beaked whale brain using magnetic resonance imaging (MRI). We describe the external and internal neuroanatomy, including sulcal and gyral patterns, and provide quantitative measurements of the cerebral cortex, amygdala, hippocampus, ventricular system, superior and inferior colliculi, cerebellum, the mid-sagittal cross-sectional area of the corpus callosum, the gyrification index, and encephalization quotient. Baird's beaked whale has a brain organization typical of odontocetes, including a large, exceptionally gyrencephalic neocortex. Both the encephalization quotient and the relative cerebellar volume are lower than in delphinids, consistent with findings in other deep-diving cetaceans. These differences may reflect energy allocation strategies related to diving behavior and body size. By contextualizing these traits within a broader mammalian neuroanatomical framework, this study contributes to our understanding of how ecological pressures may shape brain evolution, particularly in rarely-studied cetacean lineages like the Ziphiidae.