A Deep Learning-based Pipeline for Segmenting the Cerebral Cortex Laminar Structure in Histology Images.

Characterizing the anatomical structure and connectivity between cortical regions is a critical step towards understanding the information processing properties of the brain and will help provide insight into the nature of neurological disorders. A key feature of the mammalian cerebral cortex is its laminar structure. Identifying these layers in neuroimaging data is important for understanding their global structure and to help understand the connectivity patterns of neurons in the brain.

Multi-modal brain magnetic resonance imaging database covering marmosets with a wide age range.

Magnetic resonance imaging (MRI) is a non-invasive neuroimaging technique that is useful for identifying normal developmental and aging processes and for data sharing. Marmosets have a relatively shorter life expectancy than other primates, including humans, because they grow and age faster. Therefore, the common marmoset model is effective in aging research.

Development and Reorganization of Orientation Representation in the Cat Visual Cortex: Experience-Dependent Synaptic Rewiring in Early Life.

To date, numerous mathematical models have been proposed on the basis of some types of Hebbian synaptic learning to account for the activity-dependent development of orientation maps as well as neuronal orientation selectivity. These models successfully reproduced orientation map-like spatial patterns. Nevertheless, we still have questions: (1) How does synaptic rewiring occur in the visual cortex during the formation of orderly orientation maps in early life? (2) How does visual experience contribute to the maturation of orientation selectivity of visual cortical neurons and reorganize orientation maps? (3) How does the sensitive period for orientation plasticity end? In this study, we performed animal experiments and mathematical modeling to understand the mechanisms underlying synaptic rewiring for experience-dependent formation and reorganization of orientation maps.

Axonal Projections from Middle Temporal Area to the Pulvinar in the Common Marmoset.

The pulvinar, the largest thalamic nucleus in the primate brain, has connections with a variety of cortical areas and is involved in many aspects of higher brain functions. Among cortico-pulvino-cortical systems, the connection between the middle temporal area (MT) and the pulvinar has been thought to contribute significantly to complex motion recognition. Recently, the common marmoset (Callithrix jacchus), has become a valuable model for a variety of neuroscience studies, including visual neuroscience and translational research of neurological and psychiatric disorders.

Axonal Projections From the Middle Temporal Area in the Common Marmoset.

Neural activity in the middle temporal (MT) area is modulated by the direction and speed of motion of visual stimuli. The area is buried in a sulcus in the macaque, but exposed to the cortical surface in the marmoset, making the marmoset an ideal animal model for studying MT function. To better understand the details of the roles of this area in cognition, underlying anatomical connections need to be clarified.

Sound Frequency Representation in the Auditory Cortex of the Common Marmoset Visualized Using Optical Intrinsic Signal Imaging.

Natural sound is composed of various frequencies. Although the core region of the primate auditory cortex has functionally defined sound frequency preference maps, how the map is organized in the auditory areas of the belt and parabelt regions is not well known. In this study, we investigated the functional organizations of the core, belt, and parabelt regions encompassed by the lateral sulcus and the superior temporal sulcus in the common marmoset ().

Novel method of extracting motion from natural movies.

Background: The visual system in primates can be segregated into motion and shape pathways. Interaction occurs at multiple stages along these pathways. Processing of shape-from-motion and biological motion is considered to be a higher-order integration process involving motion and shape information.

3D reconstruction of brain section images for creating axonal projection maps in marmosets.

Background: The brain of the common marmoset (Callithrix jacchus) is becoming a popular non-human primate model in neuroscience research. Because its brain fiber connectivity is still poorly understood, it is necessary to collect and present connection and trajectory data using tracers to establish a marmoset brain connectivity database.

New Method: To visualize projections and trajectories of axons, brain section images were reconstructed in 3D by registering them to the corresponding block-face brain images taken during brain sectioning.

Representation of Glossy Material Surface in Ventral Superior Temporal Sulcal Area of Common Marmosets.

The common marmoset () is one of the smallest species of primates, with high visual recognition abilities that allow them to judge the identity and quality of food and objects in their environment. To address the cortical processing of visual information related to material surface features in marmosets, we presented a set of stimuli that have identical three-dimensional shapes (bone, torus or amorphous) but different material appearances (ceramic, glass, fur, leather, metal, stone, wood, or matte) to anesthetized marmoset, and recorded multiunit activities from an area ventral to the superior temporal sulcus (STS) using multi-shanked, and depth resolved multi-electrode array. Out of 143 visually responsive multiunits recorded from four animals, 29% had significant main effect only of the material, 3% only of the shape and 43% of both the material and the shape.

Supranormal orientation selectivity of visual neurons in orientation-restricted animals.

Altered sensory experience in early life often leads to remarkable adaptations so that humans and animals can make the best use of the available information in a particular environment. By restricting visual input to a limited range of orientations in young animals, this investigation shows that stimulus selectivity, e.g.

Functional columns in superior temporal sulcus areas of the common marmoset.

Cortical areas in the superior temporal sulcus (STS) of primates have been recognized as a part of the 'social brain'. In particular, biological motion stimuli elicit neuronal responses in the STS, indicating their roles in the ability to understand others' actions. However, the spatial organization of functionally identified STS cells is not well understood because it is difficult to identify the precise locations of cells in sulcal regions.

Associations between kidney position and surplus renal arteries in horseshoe kidney: case report and analysis.

We report the anatomical findings of a case of horseshoe kidney, and analyze the associations between kidney position and surplus renal arteries in horseshoe kidneys found in Japanese autopsies in the past. The horseshoe kidney of our case fused at the lower poles of the original kidneys. Its right and left upper poles were at the middle region of the first and second lumbar vertebrae, respectively.

Parallel development of orientation maps and spatial frequency selectivity in cat visual cortex.

In an early stage of the postnatal development of cats, orientation maps mature and spatial frequency selectivity is consolidated. To investigate the time course of orientation map maturation associated with the consolidation of spatial frequency selectivity, we performed optical imaging of intrinsic signals in areas 17 and 18 of cats under the stimulation of drifting square-wave gratings with different orientations and spatial frequencies. First, orientation maps for lower spatial frequencies emerged in the entire part of the lateral gyrus, which includes areas 17 and 18, and then these orientation maps in the posterior part of the lateral gyrus disappeared as orientation maps for higher spatial frequencies matured.

Single axon branching analysis in rat thalamocortical projection from the anteroventral thalamus to the granular retrosplenial cortex.

The granular retrosplenial cortex (GRS) in the rat has a distinct microcolumn-type structure. The apical tufts of dendritic bundles at layer I, which are formed by layer II neurons, co-localize with patches of thalamic terminations from anteroventral (AV) thalamic nucleus. To further understand this microcolumn-type structure in the GRS, one of remaining questions is whether this structure extends into other layers, such as layers III/IV.

Voltage-sensitive-dye imaging of microstimulation-evoked neural activity through intracortical horizontal and callosal connections in cat visual cortex.

Recently, intrinsic signal optical imaging has been widely used as a routine procedure for visualizing cortical functional maps. We do not, however, have a well-established imaging method for visualizing cortical functional connectivity indicating spatio-temporal patterns of activity propagation in the cerebral cortex. In the present study, we developed a novel experimental setup for investigating the propagation of neural activities combining the intracortical microstimulation (ICMS) technique with voltage sensitive dye (VSD) imaging, and demonstrated the feasibility of this setup applying to the measurement of time-dependent intra- and inter-hemispheric spread of ICMS-evoked excitation in the cat visual cortices, areas 17 and 18.

A postnatal critical period for orientation plasticity in the cat visual cortex.

Orientation selectivity of primary visual cortical neurons is an important requisite for shape perception. Although numerous studies have been previously devoted to a question of how orientation selectivity is established and elaborated in early life, how the susceptibility of orientation plasticity to visual experience changes in time remains unclear. In the present study, we showed a postnatal sensitive period profile for the modifiability of orientation selectivity in the visual cortex of kittens reared with head-mounted goggles for stable single-orientation exposure.

Chronically mountable goggles for persistent exposure to single orientation.

To examine the effect of experience on the developmental plasticity of functional maps in the visual cortex, we need to establish a method for a stable visual experience manipulation under the freely moving condition. For this purpose, we fabricated goggles that are chronically mounted stably on the animal's head, but easy to replace according to the animal's growth. Here we report the design of the goggles and the method of mounting them on the head of animals.

Theoretical and experimental studies of relationship between pinwheel centers and ocular dominance columns in the visual cortex.

In the visual cortex, pinwheel centers, which appear as point singularities in orientation maps, are likely to be found at the centers of ocular dominance columns in normal cats and monkeys. To elucidate the mechanism underlying the geometrical relationship, we performed computer simulation based on our correlation-based self-organization model. The simulation showed that pinwheel centers tended to be located at the ocular dominance centers at higher correlations of activities between the left- and right-eye specific pathways, whereas they tended to appear along the borders of ocular dominance columns at lower correlations.

Orientation-restricted continuous visual exposure induces marked reorganization of orientation maps in early life.

To elucidate the effect of visual experience on the development of orientation maps, we conducted intrinsic signal optical imaging of the visual cortex of kittens that were continuously exposed to a single orientation through cylindrical-lens-fitted goggles under a freely moving condition starting at post-natal week 3. We observed a rapid reorganization of orientation maps, characterized by extensive representation of exposed orientations with reduced responsiveness to unexposed orientations. The over-representation of exposed orientation was marked for 1-2 weeks of goggle rearing.

Functional organization of the cat visual cortex in relation to the representation of a uniform surface.

Neuronal activity in the early visual cortex has been extensively studied from the standpoint of contour representation. On the other hand, representation of the interior of a surface surrounded by a contour is much less well understood. Several studies have identified neurons activated by a uniform surface covering their receptive fields, but their distribution within the cortex is not yet known.