The TIGR triangle of the pineal region: a virtual reality anatomic study.

BACKGROUND: In this morphometric study, we describe the anatomy of the TIGR triangle, which is bordered by the tentorial surface of the cerebellum, the internal cerebral vein and vein of Galen complex, and the vein of Rosenthal. These structures define the window, or deep keyhole, to access the pineal region in non-midline supracerebellar infratentorial approaches. METHODS: The posterior fossa anatomy of 16 patients was studied in virtual reality (VR), and the TIGR triangles were defined and measured with special attention on its angular orientation in the posterior fossa. The angular expanse of the posterior fossa was measured and recorded as the transverse-sigmoid junction (TSJ) angle. Because a perpendicular corridor through an anatomic aperture provides the best exposure, we studied the starting point along the TSJ angle that offers the best exposure of TIGR. RESULTS: In the 31 posterior fossa sides included in the study, the perpendicular trajectory through the TIGR triangle was on average 27.13° CI 95% (range: 5.97°-48.53°) from the midline. When comparing the SCIT variants, both the paramedian and lateral approaches provided near-perpendicular trajectory through the TIGR triangle in a majority of specimens. However, the modified paramedian approach, with starting point defined as TSJ angle/3, provided the most perpendicular path through the TIGR triangle. CONCLUSION: We studied the size, spatial orientation, and morphology of the TIGR triangle. Our data indicated that the best exposure of TIGR is through a modified paramedian SCIT approach, in which the starting point one third of the way from midline to the TSJ.

Diversity and evolution of cerebellar folding in mammals.

The process of brain folding is thought to play an important role in the development and organisation of the cerebrum and the cerebellum. The study of cerebellar folding is challenging due to the small size and abundance of its folia. In consequence, little is known about its anatomical diversity and evolution. We constituted an open collection of histological data from 56 mammalian species and manually segmented the cerebrum and the cerebellum. We developed methods to measure the geometry of cerebellar folia and to estimate the thickness of the molecular layer. We used phylogenetic comparative methods to study the diversity and evolution of cerebellar folding and its relationship with the anatomy of the cerebrum. Our results show that the evolution of cerebellar and cerebral anatomy follows a stabilising selection process. We observed two groups of phenotypes changing concertedly through evolution: a group of 'diverse' phenotypes - varying over several orders of magnitude together with body size, and a group of 'stable' phenotypes varying over less than 1 order of magnitude across species. Our analyses confirmed the strong correlation between cerebral and cerebellar volumes across species, and showed in addition that large cerebella are disproportionately more folded than smaller ones. Compared with the extreme variations in cerebellar surface area, folial anatomy and molecular layer thickness varied only slightly, showing a much smaller increase in the larger cerebella. We discuss how these findings could provide new insights into the diversity and evolution of cerebellar folding, the mechanisms of cerebellar and cerebral folding, and their potential influence on the organisation of the brain across species.

The debated neuroanatomy of the fourth ventricle.

The fourth ventricle is a small, fluid-filled cavity located within the brain that plays a vital role in the body's physiological functions. Therefore, the anatomical elements forming it bear significant clinical relevance. However, the exact relations between the elements that form its roof are still debated in the neuroanatomical literature; the inferior medullary velum, and the ventricle's median aperture in particular. In some atlases, the inferior medullary velum is placed in the midline, while in others, it is placed in the transverse plane. The median aperture is also displayed in different ways in midsagittal drawings: as a round perforation of a midline velum, as a foramen in an uncharacterized part of the ventricle, and as a gap between the nodule and the brainstem. This work aims to provide a comprehensive review of the different descriptions of the fourth ventricle, in order to gain a clearer understanding of the ventricular system's structure.

Comparative histological analysis of cerebellum of representative species of elasmobranchii

SUMMARY: In elasmobranch fishes, variations in gross structural organization of cerebellum has been extensively explored. The basic histological features of cerebellum although conserved in the group but the comparative account on subtle cellular variations is largely underestimated. The present study aims to explore the histological and cellular variations in different layers of cerebellar cortex of the representative elasmobranchs' species belonging to different habitat. Our findings showed that the histological architecture of cerebellar granular layer between the examined species varies noticeably. By and large increase cellular density were observed in all the layers of cerebellum in the representative species of shark compared to ray. The findings were then compared and discussed with reference to their habitat and behavior.

En los peces elasmobranquios, las variaciones en la organización estructural general del cerebelo se han explorado ampliamente. Las características histológicas básicas del cerebelo, aunque se conservan en el grupo, pero la descripción comparativa de las variaciones celulares sutiles es limitada. El presente estudio tiene como objetivo explorar las variaciones histológicas y celulares en diferentes capas de la corteza cerebelosa de las especies representativas de elasmobranquios pertenecientes a diferentes hábitats. Nuestros hallazgos mostraron que la arquitectura histológica de la capa granular del cerebelo entre las especies examinadas varía notablemente. Se observó un gran aumento de la densidad celular en todas las capas del cerebelo en las especies representativas de tiburón en comparación con la raya. Luego, los hallazgos se compararon y discutieron con referencia a su hábitat y comportamiento.

Dissecação anatômica como estratégia para o estudo do sistema neural em fetos humanos / Anatomic dissection as a strategy for the study of the neural system in fetuses / Disección anatómica como estrategia para el estudio del sistema neural en fetos

Esse trabalho busca relatar o processo de confecção de peças anatômicas para o ensino da anatomia humana a partir de material cadavérico fetal. Os discentes do curso de medicina da Universidade Federal do Paraná (UFPR) ­ Campus Toledo participaram do programa de voluntariado acadêmico e deram atenção especial aos aspectos técnicos do processo de dissecação, bem como a experiência subjetiva desse procedimento como ferramenta de aprendizado ativo. O procedimento foi realizado na sala de preparação de cadáver da UFPR ­ Campus Toledo, utilizando instrumental de dissecação e cadáveres humanos fetais com 20, 17 e 14 semanas de idade gestacional, direcionado de modo a expor as partes constituintes do sistema neural. Foram confeccionadas peças de cérebro, cerebelo, tronco encefálico, medula espinal, nervos espinais e suas estruturas associadas. Os voluntários envolvidos foram capazes de produzir material de estudo de qualidade através da dissecação e fortalecer seu conhecimento em anatomia humana e aptidão manual. Também foi dada atenção à importância e às limitações do processo de dissecação como estratégia de aprendizado em cursos da área de saúde. pôde ser observado que a dissecação pode fazer parte de uma formação completa e bem estruturada dos discentes, que por sua vez irão integrar a sociedade e a academia. Além disso, a exposição da topografia neural fetal pode servir de referencial para posteriores estudos que venham a utilizar essas informações.

This work aims to report the confection process of anatomic pieces for teaching human anatomy from fetal cadaveric material. The students of the medicine course of Universidade Federal do Paraná (UFPR) ­ Campus Toledo, took part in the academic volunteer program and paid special attention to the technical aspects of the dissection process, as well as the subjective experience of this procedure as an active learning tool. The procedure was performed at the cadaver preparation room of the UFPR ­ Campus Toledo, using dissection tools and human fetal corpses of 20, 17 and 14 weeks of gestational ages, directed so as to expose the constituent parts of the neural system. Pieces of the brain, cerebellum, brainstem, spinal cord, spinal nerves, and its associated structures were made. The involved voluntaries were able to produce quality study material through dissection, and strengthen their knowledge in human anatomy and manual skill. Attention was also given to the importance and limitations of the dissection process as a learning strategy in health courses. it was observed that dissection can be part of a complete and well-structured training of students, who in turn will integrate society and academia. In addition, the exposure of fetal neural topography can serve as a reference for further studies that use this information

Este trabajo tiene como objetivo relatar el proceso de confección de piezas anatómicas para la enseñanza de la anatomía humana a partir de material cadavérico fetal. Los alumnos del curso de medicina de la Universidade Federal do Paraná (UFPR) - Campus Toledo, participaron del programa de voluntariado académico y prestaron especial atención a los aspectos técnicos del proceso de disección, así como a la vivencia subjetiva de este procedimiento como herramienta de aprendizaje activo. El procedimiento fue realizado en la sala de preparación de cadáveres de la UFPR - Campus Toledo, utilizando herramientas de disección y cadáveres de fetos humanos de 20, 17 y 14 semanas de edad gestacional, dirigidos de forma a exponer las partes constitutivas del sistema neural. Se realizaron piezas del cerebro, cerebelo, tronco encefálico, médula espinal, nervios espinales y sus estructuras asociadas. Los voluntarios participantes pudieron elaborar material de estudio de calidad mediante la disección y reforzar sus conocimientos de anatomía humana y habilidad manual. También se prestó atención a la importancia y las limitaciones del proceso de disección como estrategia de aprendizaje en los cursos de salud. Se observó que la disección puede formar parte de una formación completa y bien estructurada de los estudiantes, que a su vez integrarán la sociedad y el mundo académico. Además, la exposición de la topografía neural fetal puede servir de referencia para estudios posteriores que utilicen esta información.

Regulation of early cerebellar development.

The study of cerebellar development has been at the forefront of neuroscience since the pioneering work of Wilhelm His Sr., Santiago Ramón y Cajal and many others since the 19th century. They laid the foundation to identify the circuitry of the cerebellum, already revealing its stereotypic three-layered cortex and discerning several of its neuronal components. Their work was fundamental in the acceptance of the neuron doctrine, which acknowledges the key role of individual neurons in forming the basic units of the nervous system. Increasing evidence shows that the cerebellum performs a variety of homeostatic and higher order neuronal functions beyond the mere control of motor behaviour. Over the last three decades, many studies have revealed the molecular machinery that regulates distinct aspects of cerebellar development, from the establishment of a cerebellar anlage in the posterior brain to the identification of cerebellar neuron diversity at the single cell level. In this review, we focus on summarizing our current knowledge on early cerebellar development with a particular emphasis on the molecular determinants that secure neuron specification and contribute to the diversity of cerebellar neurons.

In vivo probabilistic atlas of white matter tracts of the human subthalamic area combining track density imaging and optimized diffusion tractography.

The human subthalamic area is a region of high anatomical complexity, tightly packed with tiny fiber bundles. Some of them, including the pallidothalamic, cerebello-thalamic, and mammillothalamic tracts, are relevant targets in functional neurosurgery for various brain diseases. Diffusion-weighted imaging-based tractography has been suggested as a useful tool to map white matter pathways in the human brain in vivo and non-invasively, though the reconstruction of these specific fiber bundles is challenging due to their small dimensions and complex anatomy. To the best of our knowledge, a population-based, in vivo probabilistic atlas of subthalamic white matter tracts is still missing. In the present work, we devised an optimized tractography protocol for reproducible reconstruction of the tracts of subthalamic area in a large data sample from the Human Connectome Project repository. First, we leveraged the super-resolution properties and high anatomical detail provided by short tracks track-density imaging (stTDI) to identify the white matter bundles of the subthalamic area on a group-level template. Tracts identification on the stTDI template was also aided by visualization of histological sections of human specimens. Then, we employed this anatomical information to drive tractography at the subject-level, optimizing tracking parameters to maximize between-subject and within-subject similarities as well as anatomical accuracy. Finally, we gathered subject level tracts reconstructed with optimized tractography into a large-scale, normative population atlas. We suggest that this atlas could be useful in both clinical anatomy and functional neurosurgery settings, to improve our understanding of the complex morphology of this important brain region.

Disección didáctica de fibra blanca en cerebelo humano en tres pasos: entrenamiento microneuroanatómico / 3-Step didactic white matter dissection of human cerebellum: Micro-neuroanatomical training

Objetivos: Un buen conocimiento anatómico del cerebelo es fundamental para llevar a cabo abordajes al IV ventrículo (frecuentes en la neurocirugía pediátrica) de forma segura, evitando secuelas como el mutismo cerebeloso. El propósito del presente trabajo es realizar una disección didáctica del cerebelo humano centrándonos especialmente en los pedúnculos cerebelosos y en los núcleos dentados (DN); estructuras en riesgo durante estos procedimientos. Material y métodos :Se disecó el órgano, siguiendo el método de Klingler para fibras blancas, usando material de microcirugía estándar y específico, bajo un microscopio D. F. Vasconcellos M900 con aumento x6-x40. Se utilizó una cámara Canon EOS T7 con un objetivo de 18-55 mm y se editaron las imágenes con Adobe Lightroom Classic CC y Keynote. Se emplearon métodos especiales como la iluminación endoscópica con luz LED para la obtención de algunas fotografías. Resultados: Se logró disecar con éxito los DN del cerebelo y describir su relación con los pedúnculos cerebelosos, vermis inferior y velos medulares. Mediante esta guía de tres pasos (1. cara tentorial; 2. cara suboccipital; 3. estructuras del IV ventrículo) se consiguió mostrar los elementos más importantes para el estudio del órgano y caracterizar sus implicaciones en los distintos abordajes al IV ventrículo. Conclusiones: La mejor forma de completar el estudio de neuroanatomía es la disección de especímenes, ya que aporta una visión 3 D. La transiluminación con luz LED se reveló como una herramienta útil para el registro fotográfico de estructuras del IV ventrículo, lo que mejora la visión espacial. Su principal aplicación la encontramos en los velos medulares y forámenes de la fosa romboide, ya que son permeables a la luz. La guía de disección en tres fases propuesta en este trabajo puede ayudar a los neurocirujanos, en cualquier etapa de su formación, a comprender mejor el cerebelo (AU)

Objectives: A thorough understanding of cerebellum anatomy is essential in 4th ventricle approaches (more frequent in pediatric neurosurgery), avoiding relevant complications such as cerebellar mutism. The aim of the present work is to show the feasibility of a didactic dissection of human cerebellum focusing on cerebellar peduncles and dentate nucleus (DN), which are structures at high risk during these surgical procedures. Material and methods: The cerebellum was dissected according to the Klingler method for white matter, using standard and specific microsurgery tools. Surgical microscope magnification (x6-x40) provided by a D.F. Vasconcellos M900 was required. A Canon EOS T7 18-55 mm digital camera was used and Adobe Lightroom Classic CC and Keynote were selected as photo enhancing software. Special methods such as LED light endoscopic transillumination were used for photographical reasons. Results: DN dissection was successfully achieved and the relations between these nucleus and the cerebellar peduncles, inferior vermis and medullary velums were described. Through this three steps dissection guide (1. tentorial surface; 2. suboccipital surface; 3. 4th ventricle structures), the most relevant anatomical structures were shown and its implications in different 4th ventricle approaches were characterised. Conclusion: 3 D perspective provided by real specimen anatomical dissection is critical for learning neuroanatomy. ED transillumination was shown as a useful technique for the 4th ventricle structures photographic documentation which improves spatial recognition. This benefit can be applied for the study of the relations between the medullary velums and the rhomboid fossa foramina, which are permeable to light. The proposed three-steps dissection guide helps to a better understanding of human cerebellum and to gain self-confidence, allowing safer practice for neurosurgeons in all stages of their career (AU)

3-Step didactic white matter dissection of human cerebellum: Micro-neuroanatomical training.

OBJECTIVES: A thorough understanding of cerebellum anatomy is essential in 4th ventricle approaches (more frequent in pediatric neurosurgery), avoiding relevant complications such as cerebellar mutism. The aim of the present work is to show the feasibility of a didactic dissection of human cerebellum focusing on cerebellar peduncles and dentate nucleus (DN), which are structures at high risk during these surgical procedures. MATERIAL AND METHODS: The cerebellum was dissected according to the Klingler method for white matter, using standard and specific microsurgery tools. Surgical microscope magnification (×6-×40) provided by a D.F. Vasconcellos M900 was required. A Canon EOS T7 18-55 mm digital camera was used and Adobe Lightroom Classic CC and Keynote were selected as photo enhancing software. Special methods such as LED light endoscopic transillumination were used for photographical reasons. RESULTS: DN dissection was successfully achieved and the relations between these nucleus and the cerebellar peduncles, inferior vermis and medullary velums were described. Through this three steps dissection guide (1. tentorial surface; 2. suboccipital surface; 3. 4th ventricle structures), the most relevant anatomical structures were shown and its implications in different 4th ventricle approaches were characterised. CONCLUSION: 3 D perspective provided by real specimen anatomical dissection is critical for learning neuroanatomy. LED transillumination was shown as a useful technique for the 4th ventricle structures photographic documentation which improves spatial recognition. This benefit can be applied for the study of the relations between the medullary velums and the rhomboid fossa foramina, which are permeable to light. The proposed three-steps dissection guide helps to a better understanding of human cerebellum and to gain self-confidence, allowing safer practice for neurosurgeons in all stages of their career.

Microsurgical anatomy and surgical exposure of the cerebellar peduncles.

A better understanding of the surgical anatomy of the cerebellar peduncles in different surgical approaches and their relationship with other neural structures are delineated through cadaveric dissections. We aimed to revisit the surgical anatomy of the cerebellar peduncles to describe their courses along the brain stem and the cerebellum and revise their segmental classification in surgical areas exposed through different approaches. Stepwise fiber microdissection was performed along the cerebellar tentorial and suboccipital surfaces. Multiple surgical approaches in each of the cerebellar peduncles were compared in eight silicone-injected cadaveric whole heads to evaluate the peduncular exposure areas. From a neurosurgical point of view, the middle cerebellar peduncle (MCP) was divided into a proximal cisternal and a distal intracerebellar segments; the inferior cerebellar peduncle (ICP) into a ventricular segment followed by a posterior curve and a subsequent intracerebellar segment; the superior cerebellar peduncle (SCP) into an initial congregated, an intermediate intraventricular, and a distal intramesencephalic segment. Retrosigmoid and anterior petrosectomy approaches exposed the junction of the MCP segments; telovelar, supratonsillar, and lateral ICP approaches each reached different segments of ICP; paramedian supracerebellar infratentorial, suboccipital transtentorial, and combined posterior transpetrosal approaches displayed the predecussation SCP within the cerbellomesencephalic fissure, whereas the telovelar approach revealed the intraventricular SCP within the superolateral recess of the fourth ventricle. Better understanding of the microsurgical anatomy of the cerebellar peduncles in various surgical approaches and their exposure limits constitute the most critical aspect for the prevention of surgical morbidity during surgery in and around the pons and the upper medulla. Our findings help in evaluating radiological data and planning an operative procedure for cerebellar peduncles.

The Posterior Inferior Cerebellar Artery (PICA): An Anatomical and Clinical Analysis.

AIM: To study the operative approaches for posterior inferior cerebellar artery (PICA) aneurysms or understanding the different pathologies that can affect this artery, and to present detailed knowledge of this artery?s anatomy. MATERIAL AND METHODS: The present study analyzed the different variations of the PICA?s first two segments, the anterior medullary and lateral medullary segments, regarding the number of trunks, their emergency site, and the presence or absence of hypoplasia of this artery, through microsurgical dissection of 23 fresh cadaver brains. RESULTS: Some striking variations were found, such as the absence of the left vertebral artery in one of the brains and the emergence of any PICA in another two brains studied. Moreover, variations such as hypoplastic arteries, missing trunks on one side and double or triple trunks, different emergence sites, significant PICA emergence from the superior part of the vertebral artery (59% of the trunks), and asymmetries between the right and left sides were recorded. The double origins of non-hypoplastic PICAs were found in 17% (n = 4) of patients. CONCLUSION: The results obtained in the present study indicated the great importance of the studies and reviews on the different topographies of PICA; these studies and reviews expand the knowledge and consensus on the characteristics and implications of PICA?s variations. The clinical implication of this knowledge and consensus is obtaining the best surgical strategies for clipping aneurysms and, in addition, the best choices for occlusion of the vessel affected if the territory of the main vessel has an adequate collateral circulation. From the results of the present study, it is evident that there was a significant PICA emergence from the superior part of the vertebral artery and that the double origin of non-hypoplastic trunks was also found in some patients; the latter is associated with a greater chance of aneurysms and other additional complications.

Time in Neurogenesis: Conservation of the Developmental Formation of the Cerebellar Circuitry.

The cerebellum is a conserved structure of vertebrate brains that develops at the most anterior region of the alar rhombencephalon. All vertebrates display a cerebellum, making it one of the most highly conserved structures of the brain. Although it greatly varies at the morphological level, several lines of research point to strong conservation of its internal neural circuitry. To test the conservation of the cerebellar circuit, we compared the developmental history of the neurons comprising this circuit in three amniote species: mouse, chick, and gecko. We specifically researched the developmental time of generation of the main neuronal types of the cerebellar cortex. This developmental trajectory is known for the mammalian cell types but barely understood for sauropsid species. We show that the neurogenesis of the GABAergic lineage proceeds following the same chronological sequence in the three species compared: Purkinje cells are the first ones generated in the cerebellar cortex, followed by Golgi interneurons of the granule cell layer, and lately by the interneurons of the molecular layer. In the cerebellar glutamatergic lineage, we observed the same conservation of neurogenesis throughout amniotes, and the same vastly prolonged neurogenesis of granule cells, extending much further than for any other brain region. Together these data show that the cerebellar circuitry develops following a tightly conserved chronological sequence of neurogenesis, which is responsible for the preservation of the cerebellum and its function. Our data reinforce the developmental perspective of homology, whereby similarities in neurons and circuits are likely due to similarities in developmental sequence.

Pretecto- and ponto-cerebellar pathways to the pigeon oculomotor cerebellum follow a zonal organization.

Both birds and mammals have relatively large forebrains and cerebella. In mammals, there are extensive sensory-motor projections to the cerebellum through the pontine nuclei originating from several parts of the cerebral cortex. Similar forebrain-to-cerebellum pathways exist in birds, but the organization of this circuitry has not been studied extensively. Birds have two nuclei at the base of the brainstem that are thought to be homologous to the pontine nuclei of mammals, the medial and lateral pontine nuclei (PM, PL). Additionally, birds are unique in that they have a pretectal nucleus called the medial spiriform nucleus (SpM) that, like the pontine nuclei, also receives projections from the forebrain and projects to the oculomotor cerebellum (OCb; folia VI to VIII). The OCb also receives input from the pretectal nucleus lentiformis mesencephali (LM), which analyzes visual optic flow information resulting from self-movement. In this study, we used single or double injections of fluorescent tracers to study the organization of these inputs from PM, PL, SpM and LM to the OCb in pigeons. We found that these inputs follow a zonal organization. The most medial zone in the OCb, zone A1, receives bilateral inputs from the lateral SpM, PL and LM. Zones A2 and C receive a bilateral projection from the medial SpM, and a mostly contralateral projection from PM and LM. We discuss how the pathway to zone A1 processes mainly visuo-motor information to spinal premotor areas, whereas the pathways to zone A2/C processes somato-motor and visuo-motor information and may have a feedback/modulatory role.

The evaluation of cerebellum gross morphometric measurements in subjects having migraine, ataxia, dementia and vertigo / Evaluación de las medidas morfométricas macroscópicas del cerebelo en sujetos con migraña, ataxia, demencia, vértigo

SUMMARY: This paper was aimed to determine the morphometric measurements of cerebellum using MRI in subjects having migraine, ataxia, dementia and vertigo. Three hundred twenty six (326 subjects; 80 migraine subjects; 85 vertigo subjects; 83 dementia subjects; 78 ataxia subjects) subjects ranging from 20 up to 85 years were included in this study. Cerebellum morphometric measurements were taken from subjects having brain MRI in the Radiology Department. The means and standard deviations of the measurements were: Sagittal section cerebellum superior inferior length, 56.21±5.16 mm; sagittal section cerebellum anteroposterior length, 86.36 ±5.36 mm; axial section cerebellum antereoposterior length, 66.53±5.41 mm; axial section bi-cerebellar length, 100.48±5.14 mm; coronal section cerebellum supero-inferior length,53.60±3.84 mm; coronal section bi-cerebellar length, 99.77±6.24 mm in subjects with migraine, whereas the corresponding values were 62.33±8.66 mm; 93.31±9.89 mm; 60.26±7.98 mm; 99.89±6.41 mm; 54.35±4.64 mm; 85.58±14.74 mm in subjects with vertigo, respectively. The same values were found as 58.82±8.34 mm; 86.74±13.22 mm; 58.93±8.89 mm; 97.93±6.07 mm; 50.66±4.92 mm; 84.96±14.93 mm in patients having dementia, respectively, while the same measurements were as 60.83±8.59 mm; 92.18±9.12 mm; 57.76±7.85 mm; 97.71±5.82 mm; 52.48±4.85 mm; 81.49±14.38 mm in ataxia patients, respectively. Also, ages were divided into seven groups as decades. There were found significant difference in all parameters according to sex and ages (p<0.05). The cerebellum morphometry provides important and useful knowledge in terms of comparison of abnormalities clinicians and data will be valuable for the determination of pathologies for clinical disciplines.

RESUMEN: Este trabajo tuvo como objetivo determinar las medidas morfométricas del cerebelo mediante resonancia magnética en sujetos con migraña, ataxia, demencia y vértigo. Trescientos veintiseis sujetos (80 con migraña; 85 con vértigo; 83 con demencia y 78 con ataxia) entre los 20 y los 85 años de edad se incluyeron en este estudio. Se tomaron medidas morfométricas del cerebelo de sujetos sometidos a resonancia magnética en el Departamento de Radiología. Las medias y desviaciones estándar de las medidas fueron: sección sagital longitud superoinferior del cerebelo, 56,21±5,16 mm; sección sagital longitud anteroposterior del cerebelo, 86,36 ±5,36 mm; sección axial longitud anteroposterior del cerebelo, 66,53±5,41 mm; sección axial longitud bicerebelosa, 100,48±5,14 mm; sección coronal longitud superoinferior del cerebelo, 53,60±3,84 mm; longitud bicerebelosa de la sección coronal, 99,77±6,24 mm en sujetos con migraña, mientras que los valores correspondientes fueron 62,33±8,66 mm; 93,31±9,89mm; 60,26±7,98 mm; 99,89±6,41 mm; 54,35±4,64 mm; 85,58±14,74 mm en sujetos con vértigo, respectivamente. Se encontraron los mismos valores para pacientes con demencia 58,82±8,34 mm; 86,74±13,22 mm; 58,93±8,89 mm; 97,93±6,07 mm; 50,66±4,92 mm; 84,96±14,93 mm , respectivamente, mientras que las mismas medidas fueron de 60,83±8,59 mm; 92,18±9,12 mm; 57,76±7,85 mm; 97,71±5,82 mm; 52,48±4,85 mm; 81,49±14,38 mm en pacientes con ataxia, respectivamente. Las edades se dividieron en siete grupos, cada uno en década. Se encontraron diferencias significativas en todos los parámetros según sexo y edad (p<0,05). La morfometría del cerebelo proporciona un conocimiento importante y útil en términos de comparación de anormalidades clínicas y los datos serán valiosos para la determinación de patologías para las disciplinas clínicas.

Gymkhana and pylon slalom driving training effects on the cerebellum structure.

To develop a suitable automobile design as per each driver's characteristics and state, it is important to understand the brain function in acquiring driving skills. Reportedly, the brain structures of professionals, such as athletes and musicians, and those who have received training in special skills, undergo changes with training. However, the development process of the brain in terms of acquiring driving skills has not yet been clarified. In this study, we evaluated the effects of driving training on the brain and observed an increase in the volume of the right cerebellum after short-term training (3 days). The right cerebellum is responsible for controlling the right hand and right foot, which are important for driving. Drivers train to control a vehicle smoothly at high speeds at gymkhana and pylon slalom courses, which are often used in motor sports. The brain structure was analyzed before and after training using magnetic resonance imaging. Voxel-based morphometry was used to assess possible structural changes. First, the lap times after training were clearly shortened and vehicle dynamics were more stable, indicating that the drivers' skill level clearly improved. Second, brain structural analysis revealed a volumetric increase in the right cerebellum. The cerebellum is involved in the process of learning sensory motor skills, such as smooth steering and pedal operations, driving course shape, and vehicle size perception. These results suggest a new inner model for driving operation and support the hypothesis that motor learning affects the cerebellum during vehicle driving training.

A quantitative analysis of cerebellar anatomy in birds.

The cerebellum is largely conserved in its circuitry, but varies greatly in size and shape across species. The extent to which differences in cerebellar morphology is driven by changes in neuron numbers, neuron sizes or both, remains largely unknown. To determine how species variation in cerebellum size and shape is reflective of neuron sizes and numbers requires the development of a suitable comparative data set and one that can effectively separate different neuronal populations. Here, we generated the largest comparative dataset to date on neuron numbers, sizes, and volumes of cortical layers and surface area of the cerebellum across 54 bird species. Across different cerebellar sizes, the cortical layers maintained relatively constant proportions to one another and variation in cerebellum size was largely due to neuron numbers rather than neuron sizes. However, the rate at which neuron numbers increased with cerebellum size varied across Purkinje cells, granule cells, and cerebellar nuclei neurons. We also examined the relationship among neuron numbers, cerebellar surface area and cerebellar folding. Our estimate of cerebellar folding, the midsagittal foliation index, was a poor predictor of surface area and number of Purkinje cells, but surface area was the best predictor of Purkinje cell numbers. Overall, this represents the first comprehensive, quantitative analysis of cerebellar anatomy in a comparative context of any vertebrate. The extent to which these relationships occur in other vertebrates requires a similar approach and would determine whether the same scaling principles apply throughout the evolution of the cerebellum.

SPARK-X: non-parametric modeling enables scalable and robust detection of spatial expression patterns for large spatial transcriptomic studies.

Spatial transcriptomic studies are becoming increasingly common and large, posing important statistical and computational challenges for many analytic tasks. Here, we present SPARK-X, a non-parametric method for rapid and effective detection of spatially expressed genes in large spatial transcriptomic studies. SPARK-X not only produces effective type I error control and high power but also brings orders of magnitude computational savings. We apply SPARK-X to analyze three large datasets, one of which is only analyzable by SPARK-X. In these data, SPARK-X identifies many spatially expressed genes including those that are spatially expressed within the same cell type, revealing new biological insights.

Dentate Nucleus: Connectivity-Based Anatomic Parcellation Based on Superior Cerebellar Peduncle Projections.

OBJECTIVE: Projections from the dentate nucleus (DN) follow a certain organized course to upper levels. Crossing and noncrossing fibers of the dentatorubrothalamic (DRT) tract terminate in the red nucleus and thalamus and have various connections throughout the cerebral cortex. We aimed to establish the microsurgical anatomy of the DN in relation to its efferent connections to complement the increased recognition of its surgical importance and also to provide an insight into the network-associated symptoms related to lesions and microsurgery in and around the region. METHODS: The cerebellum, DN, and superior cerebellar peduncle (SCP) en route to red nucleus were examined through fiber dissections from the anterior, posterior, and lateral sides to define the connections of the DN and its relationships with adjacent neural structures. RESULTS: The DN was anatomically divided into 4 areas based on its relation to the SCP; the lateral major, lateral anterosuperior, posteromedial, and anteromedial compartments. Most of the fibers originating from the lateral compartments were involved in the decussation of the SCP. The ventral fibers originating from the lateral anterosuperior compartment were exclusively involved in the decussation. The fibers from the posteromedial compartment ascended ipsilaterally and decussated, whereas most anteromedial fibers ascended ipsilaterally and did not participate in the decussation. CONCLUSIONS: Clarifying the anatomofunctional organization of the DN in relation to the SCP could improve microneurosurgical results by reducing the complication rates during infratentorial surgery in and around the nucleus. The proposed compartmentalization would be a major step forward in this effort.

Macro- and micro-structural cerebellar and cortical characteristics of cognitive empathy towards fictional characters in healthy individuals.

Few investigations have analyzed the neuroanatomical substrate of empathic capacities in healthy subjects, and most of them have neglected the potential involvement of cerebellar structures. The main aim of the present study was to investigate the associations between bilateral cerebellar macro- and micro-structural measures and levels of cognitive and affective trait empathy (measured by Interpersonal Reactivity Index, IRI) in a sample of 70 healthy subjects of both sexes. We also estimated morphometric variations of cerebral Gray Matter structures, to ascertain whether the potential empathy-related peculiarities in cerebellar areas were accompanied by structural differences in other cerebral regions. At macro-structural level, the volumetric differences were analyzed by Voxel-Based Morphometry (VBM)- and Region of Interest (ROI)-based approaches, and at a micro-structural level, we analyzed Diffusion Tensor Imaging (DTI) data, focusing in particular on Mean Diffusivity and Fractional Anisotropy. Fantasy IRI-subscale was found to be positively associated with volumes in right cerebellar Crus 2 and pars triangularis of inferior frontal gyrus. The here described morphological variations of cerebellar Crus 2 and pars triangularis allow to extend the traditional cortico-centric view of cognitive empathy to the cerebellar regions and indicate that in empathizing with fictional characters the cerebellar and frontal areas are co-recruited.