Journal of Comparative Neurology最新文献

{"title":"Multiple Longitudinal Tracts in the Cephalopod Arm Sensorimotor System.","authors":"Cassady S Olson, Clifton W Ragsdale","doi":"10.1002/cne.70165","DOIUrl":"10.1002/cne.70165","url":null,"abstract":"<p><p>Octopuses have an incredibly rich behavioral repertoire, exhibiting complex motor acts that require the coordination of eight highly flexible arms, each with hundreds of suckers. These movements are controlled by an axial nerve cord (ANC), analogous to the spinal cord, situated in the center of the arm musculature. The ANC has a cell body layer which forms a U-shape around its neuropil and is capped aborally, or opposite the sucker, by the cerebrobrachial tract (CBT), a massive fiber bundle known to interconnect the arms and the brain. In vertebrate spinal cords, in addition to the major fiber tracts that interconnect the brain and spinal cord, there are spinospinal connectives that coordinate complex motor behaviors across the appendages. Here, we asked with tract-tracing and immunohistochemistry, whether an octopus arm's ANC might also have intrinsic longitudinal connections for coordinated arm and sucker movements. We found that the ANC neuropil is enriched in longitudinal fibers. These fibers form distinct tracts, two within the oral (sucker-side) neuropil and two in the aboral (brachial-side) neuropil. In addition, the CBT itself demonstrates four major subtracts, and DiI labeling and dextran tracing suggest that (1) the CBT also carries arm-intrinsic longitudinal connections and (2) the CBT and the neuropil tracts can be subcategorized into those that primarily connect with the sucker and those that serve the arm musculature. We also examined the organization of fiber tracts in the ANC of the arms and tentacles of two species of squid, establishing that an aboral, extra-neuropil tract is a shared feature across all cephalopod species studied. In addition, the squids have an oral longitudinal tract, though its positioning and size varied with species and appendage. In sum, these findings describe the neural substrate for coordinating motor behaviors along the length of a cephalopod appendage.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 5","pages":"e70165"},"PeriodicalIF":2.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13145324/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nps-Expressing Neurons Receive Extensive Input From Auditory Brainstem Nuclei","authors":"Richie Zhang,&nbsp;Silvia Gasparini,&nbsp;Joel C. Geerling","doi":"10.1002/cne.70156","DOIUrl":"10.1002/cne.70156","url":null,"abstract":"<p>Neurons that express <i>Nps</i> send output to brain regions implicated in circadian function and threat responses, but less is known about the afferent control of these neurons. In this study, we used a sensitive retrograde tracer, cholera toxin beta subunit (CTb), to identify afferents to the rostral–lateral parabrachial region that contains the main concentration of <i>Nps</i>-expressing neurons. We then used Cre-dependent rabies retrograde tracing in <i>Nps</i>-2A-Cre mice to identify inputs to <i>Nps</i>-expressing neurons within this region. These neurons receive heavy input from auditory brainstem structures, including the inferior colliculus, ventral nucleus of the lateral lemniscus, superior olivary complex, and cochlear nucleus. Due to a discrepancy between sparse rabies and prominent CTb labeling extending from the ipsilateral insular to auditory areas of the cerebral cortex, we also performed anterograde labeling and found many close contacts between cortical boutons and <i>Nps-</i>expressing neurons. These findings suggest an unexpected role for auditory information in controlling the activity of <i>Nps-</i>expressing neurons and add to existing evidence suggesting that rabies is relatively insensitive to retrograde labeling of cortical afferents.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13065932/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147645356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Immature Excitatory Neurons in the Postnatal Ferret Paralaminar Nuclei and Their Relationship to the Amygdala Across Species","authors":"Lucía Inés Torrijos-Saiz,&nbsp;Marco Ghibaudi,&nbsp;Malaz Sharief,&nbsp;Lovisa Ljungqvist Brinson,&nbsp;Arturo Alvarez-Buylla,&nbsp;José Manuel García-Verdugo,&nbsp;Vicente Herranz-Pérez,&nbsp;Shawn Sorrells","doi":"10.1002/cne.70155","DOIUrl":"10.1002/cne.70155","url":null,"abstract":"<p>The amygdala paralaminar nuclei (PL) contain immature excitatory neurons that develop on a delayed timeline from birth to adulthood and are more prominent in the amygdala of humans and other primates than in rodents. Whether this expansion is linked to brain complexity or is a feature of primates is unknown. We sought to identify the PL in the ferret (<i>Mustela putorius furo</i>), a small, gyrencephalic mammal that does not belong to the primate order. Here, we show that the amygdala of juvenile (P30–P67) and adult ferrets (&gt;1 year) also contains a collection of immature excitatory neurons that express doublecortin (Dcx) and polysialylated neural cell adhesion molecule (Psa-Ncam). Similar to humans and mice, these immature neurons express Tbr1 and CoupTFII, but not FoxP2, which labels neighboring clusters of GABAergic cells in the intercalated nuclei. Ferret PL neurons extend into the ventral basolateral amygdala (BLA) and appear either in dense clusters surrounded by astroglia or as individual cells, and each subpopulation contains neurons with migratory morphology. This expansion of PL neurons into the amygdala is similar to what is seen in humans, but unlike in mice, where PL neurons are infrequent in the BLA. We compared these findings to the marmoset (<i>Callithrix jacchus</i>), a lissencephalic non-human primate, and the swine (<i>Sus scrofa domesticus</i>), a gyrencephalic mammal, and found immature neurons extending into the amygdala in both. Our study identifies the PL region of the ferret amygdala, which contains immature neurons with migratory features in juveniles and adults. Cross-species comparisons indicate that the expansion of PL neurons into the amygdala seen in primates with both high and low gyrencephalic indices has also occurred in species with gyrencephalic brains from different orders.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13045936/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147609115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sex- and Male-Morph-Specific Variation in Brain Mass and Cell Number Scaling in Solitary Centris pallida (Hymenoptera: Apidae) Bees.","authors":"Meghan Barrett, R Keating Godfrey","doi":"10.1002/cne.70163","DOIUrl":"10.1002/cne.70163","url":null,"abstract":"<p><p>Intraspecific variation in behavior is associated with variable brain resource allocation patterns: There is frequently increased tissue investment in discrete regions that support fitness-relevant cognitive abilities. However, the relationships between tissue volume and actual cell numbers have rarely been explored for insects due to methodological hurdles recently addressed via the application of isotropic fractionation. In solitary desert Centris pallida (Hymenoptera: Apidae) bees, there are two major levels of intraspecific variation: sex (males vs. females) and male morph (as a result of alternative reproductive tactics, large morph and small morph males rely on scent or sight, respectively, for mate location). Using isotropic fractionation, we separately analyzed optic lobe (OL) and central brain (CB) cell numbers of males and females to determine the impacts of sex and morph on brain cell allometry. Female bees' brains were bigger and had higher cell numbers and cell densities than males of the same size. In both sexes, total brain cell number increased with brain size, driven by increases in OL cell numbers. Between male morphs, we found that OL masses were relatively larger in small-morph males, consistent with the relationship between body size and OL volumes reported in prior studies. However, small-morph C. pallida males had fewer total cells (as represented by cell nuclei) and reduced cell density, in their OLs. Together, these data suggest that there is intraspecific and brain-region-specific variation in brain cell numbers and that variation in brain tissue volume may not match other levels of neural organization like brain cell numbers/densities.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 4","pages":"e70163"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13088941/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147698968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fiber Track Length Gradients in the Avian Sound Localization Circuit Require Conduction Velocity Gradients to Maintain Isochronicity.","authors":"David M Harris","doi":"10.1002/cne.70162","DOIUrl":"10.1002/cne.70162","url":null,"abstract":"<p><p>The chicken brainstem sound localization neural network exhibits a case where fiber length varies continuously across the fiber arrays connecting n. magnocellularis and n. laminaris. Detailed morphometric measurements were taken to quantify these length gradients. For both ipsilateral and contralateral projections, the path lengths connecting the caudal low-frequency segments are longer than those at the rostral high-frequency end, with a linear path length gradient between them. The length and the length gradient of the contralateral projection increase from hatchling to 2-4 weeks. Synchronous transmission of information is achieved if there is a conduction velocity gradient across both the ipsilateral and contralateral fiber tracts. Adjustments of conduction velocity are required at both the cellular and population levels. A model is proposed that balances conduction distances and velocities by varying the number of nodes of Ranvier along a gradient to achieve isochronicity across the entire network. Continued differential growth between fiber arrays requires a continuous timing adjustment during development and maturation. Control is assigned to the oligodendrocytes that produce and maintain myelin.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 4","pages":"e70162"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13079246/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147690233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neuroendocrine Control of the Testis: Focus on Orexinergic Modulation of Spermatogenesis.","authors":"Debarshi Sarkar, Deepanshu Joshi, Jyoti Parkash, Shio Kumar Singh","doi":"10.1002/cne.70158","DOIUrl":"https://doi.org/10.1002/cne.70158","url":null,"abstract":"<p><p>Orexins are hypothalamic neuropeptides that play an essential role in managing the sleep-wake cycle, food intake, and energy balance. There are two forms of orexins, namely orexin A (OXA) and orexin B (OXB). Orexins exert their effects through two different G-protein-coupled receptors (OX1R and OX2R). Apart from the hypothalamus, expressions of orexins and their receptors are also reported in peripheral organs including the testis, prostate, epididymis, seminal vesicle, and penis. Several studies have explored the mechanisms of action of orexin in the male gonad. This review article summarizes recent knowledge on how the orexin system regulates testicular functions like steroidogenesis, germ cell dynamics, glucose metabolism, and oxidative stress responses. By elucidating these mechanisms, the present study may prove helpful in a better understanding of the spermatogenic process. Additionally, this review article may provide new insights into the interaction of the hypothalamus with the testis and the auto/paracrine role of various neuropeptides in the regulation of male reproduction.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 4","pages":"e70158"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147690283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Little Known Facts, Controversies and Misconceptions About Cranial Motor Nuclei (and a New Classification for All Motoneurons, Cranial, and Spinal).","authors":"Margaux Sivori, Bowen Dempsey, Jean-François Brunet","doi":"10.1002/cne.70153","DOIUrl":"10.1002/cne.70153","url":null,"abstract":"<p><p>Cranial nerves represent a notoriously complex province of the neuroanatomical landscape of the vertebrates. Here, we offer a selection of the anatomic, genetic, and developmental features of their efferent component that are often misrepresented, ignored or controversial, as a complement to more exhaustive treatments of the subject. Our description reveals that efferent (or \"motor\") neurons in vertebrates represent a vague anatomic category (such as that of interneurons) rather than a true neuron type; That motor neurons fall into three bona fide types, segregated on the rostro-caudal axis of the central nervous system; That each of the three types is highly related to a type of preganglionic autonomic neuron; and that this genetic and topographical arrangement of three motor/preganglionic types correlates, not perfectly yet remarkably, with three broad physiological functions.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 4","pages":"e70153"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13080244/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147690321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dopaminergic Innervation of the Nidopallium Caudolaterale in the Japanese Quail","authors":"Defne Albayrak,&nbsp;Sinem Gencturk,&nbsp;Kevin B. Haselhuhn,&nbsp;Cem Sevinc,&nbsp;Onur Güntürkün,&nbsp;Mehdi Behroozi,&nbsp;Noemi Rook,&nbsp;Gunes Unal","doi":"10.1002/cne.70154","DOIUrl":"10.1002/cne.70154","url":null,"abstract":"<p>Convergent evolution illustrates how distantly related lineages develop comparable traits and abilities in response to similar ecological pressures. In birds, the nidopallium caudolaterale (NCL) is an executive function hub analogous to the mammalian prefrontal cortex, despite their distant roots and major differences in gross structure. While the NCL has been studied in pigeons, songbirds, and chickens, its organization in other Galliformes remains unclear. Here, we investigated the NCL in the Japanese quail (<i>Coturnix japonica</i>), a Galliform species commonly used in studies of reproductive behavior and appetitive conditioning. Using immunohistochemistry for tyrosine hydroxylase, we mapped dopaminergic projections from the ventral tegmental area and substantia nigra, quantified fiber density relative to surrounding pallial regions, and characterized axonal arborizations. We identified postsynaptic targets of tyrosine hydroxylase-positive fibers and examined their neurochemical profiles, including putative glutamatergic neurons expressing CaMKIIa and interneuron subpopulations expressing parvalbumin, calbindin, calretinin, or secretagogin. The NCL of the Japanese quail exhibited dense dopaminergic innervation primarily targeting principal neurons, with only sparse <i>en passant</i> contacts on interneuron populations, following the pattern observed in other Galliformes. These findings indicate that dopaminergic modulation of the NCL is conserved across Galliformes and support the use of the Japanese quail as a model for studying executive circuits and cognitive neurobiology in birds.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13033471/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147574218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Brain Morphology and Quantitative Assessment of Sensory Brain Areas in Southern Bluefin Tuna, Thunnus maccoyii (Scombridae, Teleostei)","authors":"Myoung Hoon Ha,&nbsp;Lucille Chapuis,&nbsp;Rebecca Glarin,&nbsp;Bradford Moffat,&nbsp;David K. Wright,&nbsp;Travis L. Dutka,&nbsp;Julian Pepperell,&nbsp;Caroline C. Kerr,&nbsp;Kara E. Yopak,&nbsp;Shaun P. Collin","doi":"10.1002/cne.70148","DOIUrl":"10.1002/cne.70148","url":null,"abstract":"<p>A quantitative comparison of the absolute and relative volumes of different brain areas is useful for predicting the sensory capabilities and behavior of large pelagic teleosts, which are difficult to study in the field or in vivo. However, the size of pelagic teleost brain regions has only been approximated using the idealized ellipsoid method, which is susceptible to over- or underestimation, as it assumes the shape of brain regions to be an idealized ellipsoid or half-ellipsoid. This study examines the gross morphology and volumes of different sensory brain areas of southern bluefin tuna <i>Thunnus maccoyii</i> using magnetic resonance imaging (MRI). The results show that the optic tectum (568 ± 11 mm³) has a larger absolute volume compared to the olfactory bulb (50 ± 5 mm³), eminentia granularis (62 ± 9 mm³), and cristae cerebelli (47 ± 3 mm³), suggesting the significance of vision for <i>T. maccoyii</i>. The full segmentation of a <i>T. maccoyii</i> brain allowed the quantification of the integration areas, which reveals that the corpus cerebelli (1299 mm³) occupies the largest proportion (35%) of total brain volume, whereas the optic tectum only occupies 15% of total brain volume. The corpus cerebelli also exhibits a rostro-caudal elongation with multiple horizontal sulci, which resemble the corpus cerebelli of some species of sharks. The results reveal that the brain of <i>T. maccoyii</i> is dominated by the locomotive area of the corpus cerebelli and highlight the benefits of using MRI when performing quantitative analyses on the brain volumes of large pelagic teleosts.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13023358/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147529772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Connectivity of the Superior Temporal Polysensory Area With the Presubiculum, Parasubiculum, Entorhinal Cortex, and Claustrum–Endopiriform Complex in the Common Marmoset (Callithrix jacchus)","authors":"Yoshiko Honda,&nbsp;Keiko Moriya-Ito,&nbsp;Nanako Hashimoto,&nbsp;Yasushi Kobayashi","doi":"10.1002/cne.70151","DOIUrl":"10.1002/cne.70151","url":null,"abstract":"<p>The rodent hippocampal–presubicular–entorhinal circuit is thought to be a key part of the circuitry involved in memory formation. In primates, additional connections are believed to enable more complex and higher-order memory information processing. We investigated whether such additional connections exist in the cortical regions adjacent to the hippocampal formation using a tracer injection method. We discovered that the marmoset parasubiculum (ParS), presubiculum (PreS) (distal portion), and entorhinal cortex (EC) (proximal or medial portion) have strong reciprocal connections with the superior temporal polysensory area (STP), which is known as a well-developed brain region in primates and where projections from diverse sensory areas converge. When the cholera toxin B subunit (CTB), a bidirectional tracer, was injected into various portions of ParS, PreS, and EC in one hemisphere, anterograde and retrograde labeling were observed in STP in both hemispheres. When CTB was injected into STP on one side, many retrogradely labeled cells were observed in layers III–V of ParS on the same side as the injection, and anterogradely labeled axons and terminal boutons were observed in layers I–III and V of ParS on both sides. In the distal portion of PreS and proximal portion of EC that were adjacent to ParS, retrogradely labeled cells were mostly observed in layer V, and substantial anterograde labeling was observed in all layers. Both in cases of STP injection and PreS (distal)-ParS-EC (proximal) injection, substantial anterograde and retrograde labeling were found in the claustrum–endopiriform complex (Cl–En). These results suggest the existence of a neural circuit that reciprocally connects STP, Cl–En, and PreS-ParS-EC, and may support functions such as higher-order multisensory memory consolidation.</p>","PeriodicalId":15552,"journal":{"name":"Journal of Comparative Neurology","volume":"534 3","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13014218/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147512516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}