Topographic anatomy of the subthalamic nucleus localized by high-resolution human brain atlas superimposing digital images of cross-sectioned surfaces and histological images of microscopic sections from frozen cadaveric brains.

Despite the recent advent of neuro-radiographic techniques, creating a 'perfect' human brain atlas providing precise and consistent images with minimal distortion is practically difficult. In this study, we created a new human brain atlas from cadaveric brains with serial sections of 50 µm thickness covering the entire basal ganglia. Human cerebral hemispheres were obtained from 10 donated cadavers and fixed in 10% formalin solution, cut in a block measuring 50 mm × 30 mm × 50 mm around the midpoint of the anterior and posterior commissures and frozen at -40 °C. Each block was cut into 50-µm-thick sections on the freezing microtome and the cross-sectioned surface was photographed. Simultaneously, every 10th slice from one sagittal hemisphere was sampled and stained using the Kluver-Barrera method. Prepared slides were photographed under light microscopy, and data from digital images of the cross-sectioned surface (DICSS) and digital images from microscopic sections (DIMS) were processed. Gray areas on DICSS largely represented areas of dense cellularity, and around subthalamic nucleus (STN), the zona incerta and field of Forel were clearly distinguishable on the anterosuperior side, as was the substantia nigra on the caudal side. DICSS successfully delineated the anatomical structure identical to the STN and surrounding contiguous nuclei. This new brain atlas will allow elucidation of anatomy that cannot be clearly disclosed from modern radiographic imaging or is very difficult to analyze with spatially inconsistent histological sections, and will contribute to further progress in anatomical studies of the human basal ganglia.

The olfactory bulb and the number of its glomeruli in the common marmoset (Callithrix jacchus).

The olfactory system has been well studied in mammals such as mice and rats. However, few studies have focused on characterizing this system in diurnal primates that rely on their sense of smell to a lesser extent due to their ecological environment. In the present study, we determined the histological organization of the olfactory bulb in the common marmoset (Callithrix jacchus). We then constructed 3-dimensional models of the glomeruli of the olfactory bulb, and estimated the number of glomeruli. Olfactory glomeruli are the functional units of olfactory processing, and have been investigated in detail using mice. There are approximately 1800 glomeruli in a mouse hemibulb, and olfactory sensory neurons expressing one selected olfactory receptor converge onto one or two glomeruli. Because mice have about 1000 olfactory receptor genes, it is proposed that the number of glomeruli in mammals is nearly double that of olfactory receptor genes. The common marmoset carries only about 400 intact olfactory receptor genes. The present study revealed that the number of glomeruli in a marmoset hemibulb was approximately 1500-1800. This result suggests that the number of glomeruli is not positively correlated with the number of intact olfactory receptor genes in mammals.

Zonal distribution of perforant path cells in layer III of the entorhinal area projecting to CA1 and subiculum in the rat.

The distribution pattern of the cells that give rise to perforant path projections, including direct entorhino-CA1 and entorhino-subicular projections, was investigated in layer III of the medial and lateral entorhinal areas in the rat using retrograde labeling with horseradish peroxidase conjugated to wheat germ agglutinin and cholera toxin B subunit. Using two-dimensional unfolded maps of the entire hippocampal and parahippocampal fields, we found that cells projecting to a certain septotemporal level of CA1 and the subiculum were distributed in a band-like zone extending across the medial and lateral entorhinal areas. The transverse axis of these zones was disposed parallel to the rhinal fissure and their longitudinal axis was perpendicular to the boundary between the medial and lateral entorhinal areas. Projections to the septal CA1 originated from the zone near the rhinal fissure, whereas those to the temporal CA1 originated from the zone far from the rhinal fissure. Each zone in both the medial and lateral entorhinal areas involved many neurons projecting to a wide proximodistal range of CA1 and the subiculum. These results suggest that the entorhino-CA1 and entorhino-subicular perforant path projections are generally organized in a band-like zonal fashion with a gradient, rather than a point-to-point topographic arrangement.

Internet-based atlas of the primate spinal cord.

In 2009, we reported an online brain atlas of the common marmoset (Callithrix jacchus) at http://marmoset-brain.org:2008. Here we report new digital images of the primate spinal cord sections added to the website. We prepared histological sections of every segment of the spinal cord of the common marmoset, rhesus monkey and Japanese monkey with various staining techniques. The sections were scanned with Carl Zeiss MIRAX SCAN at light microscopic resolution. Obtained digital data were processed and converted into multi-resolutionary images with Adobe Photoshop and Zoomify Design. These images of the primate spinal cords are now available on the web via the Internet.

Stereo Navi 2.0: software for stereotaxic surgery of the common marmoset (Callithrix jacchus).

Recently, we reported our web-accessible digital brain atlas of the common marmoset (Callithrix jacchus) at http://marmoset-brain.org:2008. Using digital images obtained during construction of this website, we developed stand-alone software for navigation of electrodes or injection needles for stereotaxic electrophysiological or anatomical experiments in vivo. This software enables us to draw lines on exchangeable section images, measure the length and angle of lines, superimpose a stereotaxic reference grid on the image, and send the image to the system clipboard. The software, Stereo Navi 2.0, is freely available at our brain atlas website.

Web-accessible digital brain atlas of the common marmoset (Callithrix jacchus).

Here we describe a web-accessible digital brain atlas of the common marmoset (Callithrix jacchus) at http://marmoset-brain.org:2008. We prepared the histological sections of the marmoset brain using various staining techniques. For virtual microscopy, high-resolution digital images of sections were obtained with Aperio Scanscope. The digital images were then converted to Zoomify files (zoomable multiresolution image files). Thereby, we could provide the multiresolution images of the marmoset brains for fast interactive viewing on the web via the Internet. In addition, we describe an automated method to obtain drawings of Nissl-stained sections.

Organization of connectivity of the rat presubiculum: II. Associational and commissural connections.

The regional, laminar, and longitudinal organization of intrinsic projections in the presubiculum was examined in the rat with the retrograde tracer horseradish peroxidase conjugated to wheat germ agglutinin and the anterograde tracer Phaseolus vulgaris-leucoagglutinin. Cells of origin of intrinsic projections in the presubiculum were distributed in layers II and V, with almost none in layers III and VI. Projections from layer II cells were bilateral and confined to layers II and V and also to the deep portion of layer I, whereas projections from layer V cells were ipsilateral and confined largely to layer V, with fewer projections to layer II. Septotemporal and proximodistal differences in both the projection and the distribution of layer II cells were found: layer II cells in the septal and mid presubiculum, especially those located in the distal part, provided long projections to the temporal presubiculum, whereas layer II cells in the temporal presubiculum provided slightly shorter projections almost entirely within the mid and temporal presubiculum. Layer II cells aggregated massively in the distal portions of the septal and mid presubiculum, but very few layer II cells were found in the most proximal part, especially in the temporal presubiculum. On the other hand, in layer V, cells of origin and their terminals were diffusely and equally distributed throughout the entire proximodistal extent of the presubiculum. Layer V cells did not project longitudinally as far as layer II cells. These longitudinal connections, in layers II and V, make it possible to merge information conveyed by parallel pathways in the presubiculum.