Ultrastructure of the dorsal claustrum in cat. II. Synaptic organization.

The claustrum is a bilateral subcortical nucleus situated between the insular cortex and the striatum in the brain of all mammals. It consists of two embryologically distinct subdivisions - dorsal and ventral claustrum. The claustrum has high connectivity with various areas of the cortex, subcortical and allocortical structures. It has long been suggested that the various claustral connections have different types of synaptic contacts at the claustral neurons. However, to the best of our knowledge, the literature data on the ultrastructural organization of the different types of synaptic contacts in the dorsal claustrum are very few. Therefore, the aim of our study was to observe and describe the synaptic organization of the dorsal claustrum in the cat. We used a total of 10 adult male cats and conducted an ultrastructural study under a transmission electron microscope as per established protocol. We described a multitude of dendritic spines, which were subdivided into two types - with and without foot processes. Based on the size and shape of the terminal boutons, the quantity and distribution of vesicles and the characteristic features of the active synaptic zone, we described six types of synaptic boutons, most of which formed asymmetrical synaptic contacts. Furthermore, we reported the presence of axo-dendritic, axo-somatic, dendro-dendritic and axo-axonal synapses. The former two likely represent the morphological substrate of the corticoclaustral pathway, while the remaining two types have the ultrastructural features of inhibitory synapses, likely forming a local inhibitory circuit in the claustrum. In conclusion, the present study shares new information about the neuropil of the claustrum and proposes a systematic classification of the types of synaptic boutons and contacts observed in the dorsal claustrum of the cat, thus supporting its key and complex role as a structure integrating various information within the brain.

Comparative investigation of neuronal nitric oxide synthase immunoreactivity in rat and human claustrum.

We compared the distribution, density and morphological characteristics of nitric oxide synthase-immunoreactive (NOS-ir) neurons in the rat and human claustrum. These neurons were categorized by diameter into three main types: large, medium and small. In the human claustrum, large neurons ranged from 26 to 40µm in diameter, medium neurons from 20 to 25µm and small neurons from 13 to 19µm. In the rat claustrum, large neurons ranged from 19 to 23µm in diameter, medium neurons from 15 to 18µm and small neurons from 10 to 14µm. The cell bodies of large and medium neurons varied broadly in shape - multipolar, elliptical, bipolar and irregular, consistent with a projection neuron phenotype. The small neurons were most seen as being oval or elliptical in shape, resembling an interneuron phenotype. Based on a quantitative comparison of their dendritic characteristics, the NOS-ir neurons of humans and rats displayed a statistically significant difference.

Sodium P-Aminosalicylic Acid Improved Manganese-Induced Learning and Memory Dysfunction via Restoring the Ultrastructural Alterations and γ-Aminobutyric Acid Metabolism Imbalance in the Basal Ganglia.

Excessive intake of manganese (Mn) may cause neurotoxicity. Sodium para-aminosalicylic acid (PAS-Na) has been used successfully in the treatment of Mn-induced neurotoxicity. The γ-aminobutyric acid (GABA) is related with learning and memory abilities. However, the mechanism of PAS-Na on improving Mn-induced behavioral deficits is unclear. The current study was aimed to investigate the effects of PAS-Na on Mn-induced behavioral deficits and the involvement of ultrastructural alterations and γ-aminobutyric acid (GABA) metabolism in the basal ganglia of rats. Sprague-Dawley rats received daily intraperitoneally injections of 15 mg/kg MnCl2.4H2O, 5d/week for 4 weeks, followed by a daily back subcutaneously (sc.) dose of PAS-Na (100 and 200 mg/kg), 5 days/week for another 3 or 6 weeks. Mn exposure for 4 weeks and then ceased Mn exposure for 3 or 6 weeks impaired spatial learning and memory abilities, and these effects were long-lasting. Moreover, Mn exposure caused ultrastructural alterations in the basal ganglia expressed as swollen neuronal with increasing the electron density in the protrusions structure and fuzzed the interval of neuropil, together with swollen, focal hyperplasia, and hypertrophy of astrocytes. Additionally, the results also indicated that Mn exposure increased Glu/GABA values as by feedback loops controlling GAT-1, GABAA mRNA and GABAA protein expression through decreasing GABA transporter 1(GAT-1) and GABA A receptor (GABAA) mRNA expression, and increasing GABAA protein expression in the basal ganglia. But Mn exposure had no effects on GAT-1 protein expression. PAS-Na treatment for 3 or 6 weeks effectively restored the above-mentioned adverse effects induced by Mn. In conclusion, these findings suggest the involvement of GABA metabolism and ultrastructural alterations of basal ganglia in PAS-Na's protective effects on the spatial learning and memory abilities.

Synaptic organization of striate cortex projections in the tree shrew: A comparison of the claustrum and dorsal thalamus.

The tree shrew (Tupaia belangeri) striate cortex is reciprocally connected with the dorsal lateral geniculate nucleus (dLGN), the ventral pulvinar nucleus (Pv), and the claustrum. In the Pv or the dLGN, striate cortex projections are thought to either strongly "drive", or more subtly "modulate" activity patterns respectively. To provide clues to the function of the claustrum, we compare the synaptic arrangements of striate cortex projections to the dLGN, Pv, and claustrum, using anterograde tracing and electron microscopy. Tissue was additionally stained with antibodies against γ-aminobutyric acid (GABA) to identify GABAergic interneurons and non-GABAergic projection cells. The striate cortex terminals were largest in the Pv (0.94 ± 0.08 µm2 ), intermediate in the claustrum (0.34 ± 0.02 µm2 ), and smallest in the dLGN (0.24 ± 0.01 µm2 ). Contacts on interneurons were most common in the Pv (39%), intermediate in the claustrum (15%), and least common in the dLGN (12%). In the claustrum, non-GABAergic terminals (0.34 ± 0.01 µm2 ) and striate cortex terminals were not significantly different in size. The largest terminals in the claustrum were GABAergic (0.51 ± 0.02 µm2 ), and these terminals contacted dendrites and somata that were significantly larger (1.90 ± 0.30 µm2 ) than those contacted by cortex or non-GABAergic terminals (0.28 ± 0.02 µm2 and 0.25 ± 0.02 µm2 , respectively). Our results indicate that the synaptic organization of the claustrum does not correspond to a driver/modulator framework. Instead, the circuitry of the claustrum suggests an integration of convergent cortical inputs, gated by GABAergic circuits. J. Comp. Neurol. 525:1403-1420, 2017. © 2016 Wiley Periodicals, Inc.

Magnetization Transfer and Amide Proton Transfer MRI of Neonatal Brain Development.

Purpose. This study aims to evaluate the process of brain development in neonates using combined amide proton transfer (APT) imaging and conventional magnetization transfer (MT) imaging. Materials and Methods. Case data were reviewed for all patients hospitalized in our institution's neonatal ward. Patients underwent APT and MT imaging (a single protocol) immediately following the routine MR examination. Single-slice APT/MT axial imaging was performed at the level of the basal ganglia. APT and MT ratio (MTR) measurements were performed in multiple brain regions of interest (ROIs). Data was statistically analyzed in order to assess for significant differences between the different regions of the brain or correlation with patient gestational age. Results. A total of 38 neonates were included in the study, with ages ranging from 27 to 41 weeks' corrected gestational age. There were statistically significant differences in both APT and MTR measurements between the frontal lobes, basal ganglia, and occipital lobes (APT: frontal lobe versus occipital lobe P = 0.031 and other groups P = 0.00; MTR: frontal lobe versus occipital lobe P = 0.034 and other groups P = 0.00). Furthermore, APT and MTR in above brain regions exhibited positive linear correlations with patient gestational age. Conclusions. APT/MT imaging can provide valuable information about the process of the neonatal brain development at the molecular level.

Network architecture of the cerebral nuclei (basal ganglia) association and commissural connectome.

The cerebral nuclei form the ventral division of the cerebral hemisphere and are thought to play an important role in neural systems controlling somatic movement and motivation. Network analysis was used to define global architectural features of intrinsic cerebral nuclei circuitry in one hemisphere (association connections) and between hemispheres (commissural connections). The analysis was based on more than 4,000 reports of histologically defined axonal connections involving all 45 gray matter regions of the rat cerebral nuclei and revealed the existence of four asymmetrically interconnected modules. The modules form four topographically distinct longitudinal columns that only partly correspond to previous interpretations of cerebral nuclei structure-function organization. The network of connections within and between modules in one hemisphere or the other is quite dense (about 40% of all possible connections), whereas the network of connections between hemispheres is weak and sparse (only about 5% of all possible connections). Particularly highly interconnected regions (rich club and hubs within it) form a topologically continuous band extending through two of the modules. Connection path lengths among numerous pairs of regions, and among some of the network's modules, are relatively long, thus accounting for low global efficiency in network communication. These results provide a starting point for reexamining the connectional organization of the cerebral hemispheres as a whole (right and left cerebral cortex and cerebral nuclei together) and their relation to the rest of the nervous system.

Striosome-dendron bouquets highlight a unique striatonigral circuit targeting dopamine-containing neurons.

The dopamine systems of the brain powerfully influence movement and motivation. We demonstrate that striatonigral fibers originating in striosomes form highly unusual bouquet-like arborizations that target bundles of ventrally extending dopamine-containing dendrites and clusters of their parent nigral cell bodies. Retrograde tracing showed that these clustered cell bodies in turn project to the striatum as part of the classic nigrostriatal pathway. Thus, these striosome-dendron formations, here termed "striosome-dendron bouquets," likely represent subsystems with the nigro-striato-nigral loop that are affected in human disorders including Parkinson's disease. Within the bouquets, expansion microscopy resolved many individual striosomal fibers tightly intertwined with the dopamine-containing dendrites and also with afferents labeled by glutamatergic, GABAergic, and cholinergic markers and markers for astrocytic cells and fibers and connexin 43 puncta. We suggest that the striosome-dendron bouquets form specialized integrative units within the dopamine-containing nigral system. Given evidence that striosomes receive input from cortical regions related to the control of mood and motivation and that they link functionally to reinforcement and decision-making, the striosome-dendron bouquets could be critical to dopamine-related function in health and disease.

Anatomical localization of Cav3.1 calcium channels and electrophysiological effects of T-type calcium channel blockade in the motor thalamus of MPTP-treated monkeys.

Conventional anti-Parkinsonian dopamine replacement therapy is often complicated by side effects that limit the use of these medications. There is a continuing need to develop nondopaminergic approaches to treat Parkinsonism. One such approach is to use medications that normalize dopamine depletion-related firing abnormalities in the basal ganglia-thalamocortical circuitry. In this study, we assessed the potential of a specific T-type calcium channel blocker (ML218) to eliminate pathologic burst patterns of firing in the basal ganglia-receiving territory of the motor thalamus in Parkinsonian monkeys. We also carried out an anatomical study, demonstrating that the immunoreactivity for T-type calcium channels is strongly expressed in the motor thalamus in normal and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys. At the electron microscopic level, dendrites accounted for >90% of all tissue elements that were immunoreactive for voltage-gated calcium channel, type 3.2-containing T-type calcium channels in normal and Parkinsonian monkeys. Subsequent in vivo electrophysiologic studies in awake MPTP-treated Parkinsonian monkeys demonstrated that intrathalamic microinjections of ML218 (0.5 µl of a 2.5-mM solution, injected at 0.1-0.2 µl/min) partially normalized the thalamic activity by reducing the proportion of rebound bursts and increasing the proportion of spikes in non-rebound bursts. The drug also attenuated oscillatory activity in the 3-13-Hz frequency range and increased gamma frequency oscillations. However, ML218 did not normalize Parkinsonism-related changes in firing rates and oscillatory activity in the beta frequency range. Whereas the described changes are promising, a more complete assessment of the cellular and behavioral effects of ML218 (or similar drugs) is needed for a full appraisal of their anti-Parkinsonian potential.

Topographic organization of the human and non-human primate subthalamic nucleus.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is used to relieve motor symptoms of Parkinson's disease. A tripartite system of STN subdivisions serving motoric, associative, and limbic functions was proposed, mainly based on tracing studies, which are limited by low numbers of observations. The evidence is compelling and raises the question as to what extent these functional zones are anatomically segregated. The majority of studies indicate that there is anatomical overlap between STN functional zones. Using ultrahigh-resolution magnetic resonance imaging techniques it is now possible to visualize the STN with high spatial resolution, and it is feasible that in the near future stereotactic guided placement of electrical stimulators aided by high-resolution imaging will allow for more specific stimulation of the STN. The neuroanatomical and functional makeup of these subdivisions and their level of overlap would benefit from clarification before serving as surgical targets. We discuss histological and imaging studies, as well as clinical observations and electrophysiological recordings in DBS patients. These studies provide evidence for a topographical organization within the STN, although it remains unclear to what extent functionally and anatomically distinct subdivisions overlap.

A novel, fully automated, observer-independent program for semiquantifying striatal 123I-FP-CIT uptake / Un nuevo programa, totalmente automático e independiente del observador para semi-cuantificar la captación estriatal de 123I-FP-CIT

Objective: To describe and validate a novel, fully automated program specifically designed for the semi- quantification of striatal 123I-FP-CIT uptake using volumes of interest (VOI) analysis. Material and methods: The proposed algorithm is based on a template that mimics the striatal 123 I-FP-CIT uptake in a healthy subjects, derived from defined anatomical VOIs available from WFU PickAtlas. Four SPECT studies of the anthropomorphic Alderson phantom filled with variable radioactive concentrations were acquired for the experimental validation. Experimental SPECT images were spatially normalized with respect to the previously created template. The binary VOIs corresponding to left caudate and puta- men and right caudate and putamen, which were used to construct the template, were projected onto the experimental images to obtain the counts for these regions. To minimize the partial volume effect, a percentage of the voxels in these regions (threshold), rather than all of them, was used. A binary occipital VOI was used to quantify the non-specific uptake. Experimental binding potentials (BPs) were calculated from the counts in these regions. True BPs were calculated from aliquots taken from the solutions used to fill the phantom. Results: There were statistically significant differences in the experimental BP values (p < 0.002) accord- ing to the percentage of voxels used. A highly significant correlation was achieved between true and experimental BP values, regardless of the percentage of voxels included for quantification. Conclusions: Our novel, observer-independent program automatically performs the semiquantification of striatal 123I-FP-CIT uptake in experimental studies (AU)

Objetivos: Describir y validar un nuevo software, totalmente automático, específicamente diseñado para semicuantificar la captación estriatal de 123I-FP-CIT usando volúmenes de interés (VOIs). Material y métodos: El algoritmo propuesto se basa en una plantilla que remeda la captación estriatal de 123I-FP-CIT en un sujeto sano, obtenida a partir de VOIs anatómicos definidos en WFU PickAtlas. Para la validación experimental de este algoritmo se adquirieron 4 estudios SPECT del maniquí antropomórfico Alderson llenado con concentraciones radioactivas variables. Las imágenes SPECT experimentales se normalizaron espacialmente respecto a la plantilla creada. Los VOIs binarios correspondientes a núcleo caudado y putámen derechos e izquierdos, utilizados para disen ̃ar la plantilla, se proyectaron sobre las imágenes experimentales para obtener las cuentas en estas regiones. Para minimizar los efectos de volumen parcial se utilizó un porcentaje de vóxeles, en vez de utilizar todos los vóxeles contenidos en estos VOIs. Se ha utilizado un VOI binario situado en región occipital para cuantificar la unión no específica. Los potenciales de unión (BPs) experimentales se calcularon a partir de las cuentas obtenidas en estas regiones. Los BPs reales se calcularon a partir de alícuotas tomadas de las soluciones utilizadas para llenar el maniquí. Resultados: Hubo diferencias estadísticamente significativas en los BPs experimentales en función del porcentaje de vóxeles utilizados para la cuantificación (p < 0.002). Se alcanzó una alta correlación entre los BPs reales y los experimentales, independientemente del porcentaje de vóxeles utilizados para la cuantificación. Conclusiones: Este nuevo programa automático e independiente del observador realiza la semicuantificación de la captación estriatal de 123I-FP-CIT en estudios experimentales (AU)

Decreased mitochondrial bioenergetics and calcium buffering capacity in the basal ganglia correlates with motor deficits in a nonhuman primate model of aging.

Altered mitochondrial function in the basal ganglia has been hypothesized to underlie cellular senescence and promote age-related motor decline. We tested this hypothesis in a nonhuman primate model of human aging. Six young (6-8 years old) and 6 aged (20-25 years old) female Rhesus monkeys (Macaca mulatta) were behaviorally characterized from standardized video records. Additionally, we measured mitochondrial bioenergetics along with calcium buffering capacity in the substantia nigra and putamen (PUT) from both age groups. Our results demonstrate that the aged animals had significantly reduced locomotor activity and movement speed compared with younger animals. Moreover, aged monkeys had significantly reduced ATP synthesis capacity (in substantia nigra and PUT), reduced pyruvate dehydrogenase activity (in PUT), and reduced calcium buffering capacity (in PUT) compared with younger animals. Furthermore, this age-related decline in mitochondrial function in the basal ganglia correlated with decline in motor function. Overall, our results suggest that drug therapies designed to enhance altered mitochondrial function may help improve motor deficits in the elderly.

The discrepancy between the absence of copper deposition and the presence of neuronal damage in the brain of Atp7b(-/-) mice.

Wilson's disease (WD) is caused by mutations within the copper-transporting ATPase (ATP7B), characterized by copper deposition in various organs, principally the liver and the brain. With the availability of Atp7b(-/-) mice, the valid animal model of WD, the mechanism underlying copper-induced hepatocyte necrosis has been well understood. Nonetheless, little is known about the adverse impact of copper accumulation on the brain in WD. Therefore, the aim of this study was to identify copper disturbances according to various brain compartments and further dissect the causal relationship between copper storage and neuronal damage using Atp7b(-/-) mice. Copper levels in the liver, whole brain, brain compartments and basal ganglia mitochondria of Atp7b(-/-) mice and age-matched controls were measured by atomic absorption spectroscopy. Delicate electron microscopic studies on hepatocytes and neurons in the basal ganglia were performed. Here we further confirmed the remarkably elevated copper content and abnormal ultrastructure findings in livers of Atp7b(-/-) mice. Interestingly, we found the ultrastructure abnormalities in neurons of the basal ganglia of Atp7b(-/-) mice, whereas copper deposition was not detected in the whole brain, even within the basal ganglia and its mitochondria. The disparity provided a new understanding of neuronal dysfunction in WD, and strongly indicated that copper might not be the sole causative player and other unidentified pathogenic factors could enhance the toxic effects of copper on neurons in WD.

[THE ORGANIZATION OF PROJECTIONS OF MIDBRAIN LATERAL TEGMENTAL NUCLEI THE TO BRAIN BASAL GANGLIA IN DOGS].

The organization of the projections of midbrain lateral tegmental nuclei (peripeduncular nucleus, paralemniscal nucleus, nucleus of the brachium of inferior colliculus) to functionally diverse nuclei of the basal ganglia system was studied in dogs (n = 34) by the method of retrograde axonal transport of horse-radish peroxidase. It was found that the midbrain nuclei studied were involved in functionally different circuits, containing the basal ganglia as their components. These nuclei innervate the regions of the putamen, globus pallidus, cuneate nucleus, subcuneate nucleus, which are the motor or the limbic structures on the basis of their predominant connections with the motor or the limbic brain nuclei, and also regions of the caudate nucleus, nucleus accumbens, entopeduncular nucleus, compact part of the pedunculopontine nucleus, which receive the projections from the functionally various structures. The analysis of Nissl-stained frontal sections allowed to refine the anatomical topography of the individual nuclei of the midbrain lateral tegmentum. The cholinergic nature of their neurons was demonstrated based on of the positive histochemical reaction to NADPH diaphorase.

[On the question of the organization of brain function: cortical associations, «disconnection¼ syndrome and higher brain functions].

The review considers the structural/functional brain organization, the disturbance of which is accompanied by the development of cognitive and behavioral disorders. The significance of the disruption of parallel circuits connecting frontal lobes with subcortical structures (the basal ganglia, thalamus, cerebellum) is highlighted. This disruption is clinically described as "disconnection" syndrome. The associations between the basal ganglia and the cortex of the large cerebral hemispheres responsible for motor, cognitive and emotional/behavioral functions do not restricted to these spheres and is characteristic not only of frontal brain areas. There are circuits connecting other brain compartments and the basal ganglia that provide perception, and are involved in decision making on the basis of input information of different modalities.The improvement of understanding of the pathophysiology and neurochemistry of these structures opens new possibilities for selective action on some or other circuit to achieve the best therapeutic result.

Microstructural brain abnormalities and symptom dimensions in child and adolescent patients with obsessive-compulsive disorder: a diffusion tensor imaging study.

BACKGROUND: The aims of this study were to determine white matter (WM) microstructure abnormalities in obsessive-compulsive disorder (OCD) using diffusion tensor imaging, and to investigate whether these abnormalities differ according to OCD symptom dimensions. METHODS: Sixty-three child and adolescent OCD patients (11-18 years old) and 37 healthy subjects matched for gender, age, and estimated intelligence quotient were assessed by means of psychopathology scales and diffusion tensor magnetic resonance imaging. RESULTS: Compared with healthy controls OCD patients showed a significant decrease (t = 3.79, P = .049 FDR-corrected) in fractional anisotropy (FA) in the anterior region of the corpus callosum (CC). In addition, mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) values were significantly increased in OCD compared with controls in the CC and in several WM regions of the cingulate, frontal and occipital lobes, basal ganglia, cerebellum, and pons. Compared with healthy controls, OCD patients presenting the harm/checking dimension showed decreased FA in the CC and in the left anterior cingulate gyrus and caudate nucleus, whereas patients with a predominant contamination/washing symptom dimension presented significantly decreased FA in the left midbrain, lentiform nucleus, insula, and thalamus, and increased MD, AD, and RD in both the anterior lobes of cerebellum and in the pons. CONCLUSIONS: The findings suggest WM abnormalities at the microstructural level in the pathogenesis of OCD. Moreover, WM abnormalities in OCD may vary according to the specific OCD symptom dimensions, thus indicating the clinical heterogeneity of the condition.

Neuropeptide Y immunoreactivity in the cat claustrum: A light- and electron-microscopic investigation.

The claustrum is a telencephalic nucleus located ventrolateral to the basal ganglia in the mammalian brain. It has an extensive reciprocal connectivity with most if not all of the cerebral cortex, in particular, primary sensory areas. However, despite renewed and growing interest amongst investigators, there remains a paucity of data concerning its peptidergic profile. The aim of the present study was to examine the presence, morphology, distribution and ultrastructure of neuropeptide Y-immunoreactive (NPY-ir) neurons and fibers in the claustrum of the cat. Ten adult healthy cats from both sexes were used. All animals received human and ethical treatment in accordance with the Principles of Laboratory Animal Care. Subjects were irreversibly anesthetized and transcardially perfused with fixative solution containing glutaraldehyde and paraformaldehyde. Brains were promptly removed, postfixed and sectioned. Slices were incubated with polyclonal anti-NPY antibodies according to the standard avidin-biotin-peroxidase complex method adopted by our Department of Anatomy, Histology and Embryology. NPY-ir neurons and fibers were found to be diffusely distributed throughout the claustrum, with no obvious topographic or functional patterning other than larger numbers in its central/broadest part (stereotaxic planes A12-A16). Neurons were generally classified by diameter into three sizes: small (under 17 µm), medium (17-25 µm) and large (over 25 µm). Staining density is varied with some neurons appearing darker than others. At the electron-microscopic level NPY immunoproduct was observed within neurons, dendrites and terminal boutons, each differing relative to their ultrastructural attributes. Two types of NPY-ir synaptic boutons were found. Lastly, it is of interest to note that gender-specific differences were not observed.

Astrocytic inclusions in progressive supranuclear palsy and corticobasal degeneration.

Tufted astrocytes (TAs) in progressive supranuclear palsy (PSP) and astrocytic plaques (APs) in corticobasal degeneration (CBD) have been regarded as the pathological hallmarks of major sporadic 4-repeat tauopathies. To better define the astrocytic inclusions in PSP and CBD and to outline the pathological features of each disease, we reviewed 95 PSP cases and 30 CBD cases that were confirmed at autopsy. TAs exhibit a radial arrangement of thin, long, branching accumulated tau protein from the cytoplasm to the proximal processes of astrocytes. APs show a corona-like arrangement of tau aggregates in the distal portions of astrocytic processes and are composed of fuzzy, short processes. Immunoelectron microscopic examination using quantum dot nanocrystals revealed filamentous tau accumulation of APs located in the immediate vicinity of the synaptic structures, which suggested synaptic dysfunction by APs. The pathological subtypes of PSP and CBD have been proposed to ensure that the clinical phenotypes are in accordance with the pathological distribution and degenerative changes. The pathological features of PSP are divided into 3 representative subtypes: typical PSP type, pallido-nigro-luysian type (PNL type), and CBD-like type. CBD is divided into three pathological subtypes: typical CBD type, basal ganglia- predominant type, and PSP-like type. TAs are found exclusively in PSP, while APs are exclusive to CBD, regardless of the pathological subtypes, although some morphological variations exist, especially with regard to TAs. The overlap of the pathological distribution of PSP and CBD makes their clinical diagnosis complicated, although the presence of TAs and APs differentiate these two diseases. The characteristics of tau accumulation in both neurons and glia suggest a different underlying mechanism with regard to the sites of tau aggregation and fibril formation between PSP and CBD: proximal-dominant aggregation of TAs and formation of filamentous NFTs in PSP in contrast to the distal-dominant aggregation of APs and formation of less filamentous pretangles in CBD.

Pretangles and neurofibrillary changes: similarities and differences between AD and CBD based on molecular and morphological evolution.

Pretangles are cytoplasmic tau immunoreactivity in neurons without apparent formation of fibrillary structures. In Alzheimer disease, such tau deposition is considered to represent a premature state prior to fibril formation (AD-pretangles), later to form neurofibrillary tangles and finally ghost tangles. This morphological evolution from pretangles to ghost tangles is in parallel with their profile shift from four repeat (4R) tau-positive pretangles to three repeat (3R) tau-positive ghost tangles with both positive neurofibrillary tangles in between. This complementary shift of tau profile from 4R to 3R suggests that these tau epitopes are represented interchangeably along tangle evolution. Similar tau immunoreactivity without fibril formation is also observed in corticobasal degeneration (CBD-pretangles). CBD-pretangles and AD-pretangles share: (i) selective 4R tau immunoreactivity without involvement of 3R tau; and (ii) argyrophilia with Gallyas silver impregnation. However, CBD-pretangles neither evolve into ghost tangles nor exhibit 3R tau immunoreactivity even at the advanced stage. Because electron microscopic studies on these pretangles are quite limited, it remains to be clarified whether such differences in later evolution are related to their primary ultrastructures, potentially distinct between AD and CBD. As double staining for 3R and 4R tau clarified complementary shift from 4R to 3R tau along evolution from pretangles to ghost tangles, double immunoelectron microscopy, if possible, may clarify similar profile shifts in relation to each tau fibril at the ultrastructural dimension. This will provide a unique viewpoint on how molecular (epitope) representations are related to pathogenesis of fibrillary components.

[The analysis of the possible pathways of carrying information and its integration in the projection systems, connecting the basal ganglia with the rostromedial tegmental nucleus dog's brain].

The structural foundation of processing of the information in the basal ganglia morphofunctional system was studied on the basis of the analysis of the projections between the separate parts of the rostral and thecaudal compartments of the rostromedial tegmental nucleus (RMTN) and the functionally different segments of the striatal and the pallidal structures, which were investigated by the method of the retrograde axonal transport. The elements of the topic, showing to opportunity of segregated carrying of the information between the limbic segments RMTN and the limbic striopallidal fields were revealed in the organization of the projections between the named structures in dog. But the convergence of the projection fibers, proceeding from the neurons of the functionally different parts of RMTN observed in the majority of striopallidal structures that testify about the opportunity of the integration of the functionally different information in them. The revealed labeled RMTN "reticular" neurons with sparsely branching dendrites and long axons, which are projected to the striopallidal structures, also testify about the integrative function of the investigated nucleus. The possible ways of carrying of the motor and the limbic information and its integration in the structures of the studied system and opportunity of the utilization of the received dates for making of the new models, which allow to understand better the mechanism of basal ganglia functioning in normal and pathological conditions are discussed.

Automated in-chamber specimen coating for serial block-face electron microscopy.

When imaging insulating specimens in a scanning electron microscope, negative charge accumulates locally ('sample charging'). The resulting electric fields distort signal amplitude, focus and image geometry, which can be avoided by coating the specimen with a conductive film prior to introducing it into the microscope chamber. This, however, is incompatible with serial block-face electron microscopy (SBEM), where imaging and surface removal cycles (by diamond knife or focused ion beam) alternate, with the sample remaining in place. Here we show that coating the sample after each cutting cycle with a 1-2 nm metallic film, using an electron beam evaporator that is integrated into the microscope chamber, eliminates charging effects for both backscattered (BSE) and secondary electron (SE) imaging. The reduction in signal-to-noise ratio (SNR) caused by the film is smaller than that caused by the widely used low-vacuum method. Sample surfaces as large as 12 mm across were coated and imaged without charging effects at beam currents as high as 25 nA. The coatings also enabled the use of beam deceleration for non-conducting samples, leading to substantial SNR gains for BSE contrast. We modified and automated the evaporator to enable the acquisition of SBEM stacks, and demonstrated the acquisition of stacks of over 1000 successive cut/coat/image cycles and of stacks using beam deceleration or SE contrast.