Toshiki Tani - Academia.edu (original) (raw)

Papers by Toshiki Tani

2009 IEEE 8th International Conference on Development and Learning, 2009

... Science Institute, Wako, Saitama 351-0198, Japan (corresponding author to provide phone: +81-... more ... Science Institute, Wako, Saitama 351-0198, Japan (corresponding author to provide phone: +81-48-462-1111, ext.7153; fax: +81-48-467-9684; e-mail: yoshi-t@brain ... 1 week and for adult mice for 1 week (n = 8), 2 weeks (n = 4) and 3 weeks (n = 4). A light (250 300 lx) and dark ...

Neuroscience Research, 2011

Areas in and around superior temporal sulcus (STS) are thought to be important to social behavior... more Areas in and around superior temporal sulcus (STS) are thought to be important to social behavior (e.g., recognizing other's action and intention). Although new-world monkey marmosets have strong pro-social nature, data related connection of STS is scanty. We performed retrograde tracer (CTB-Alexa 488 or 555) injection around superior temporal cortex of the marmosets. So far, we have made three injections into dorsal and ventral parts of middle STS and dorsal part of caudal STS. We found each injection resulted in unique input pattern, like macaque monkey (Selzer and Pandya, 1994). But, in general, areas around STS receive strong projection form multiple sources (insular, parietal cortex, frontal and occipital cortices), as expected as its multi-modal nature. Based on these results, we will discuss the subdivision of the marmoset areas around STS, by combining with electrophysiology and cytoarchitectures. Research fund: KAKENHI (22300104).

NeuroImage, 2006

To elucidate the effect of visual experience on the development of orientation maps, we conducted... more 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. A longer period of goggle rearing, however, decreased the degree of over-representation, which still remained at a remarkable level. Dark rearing episodes daily interleaved between single orientation exposures moderated the over-representation effect. Unit recording from goggle-reared kittens showed preferred orientations consistent with optical imaging. Using c-Fos immunoreactivity mapping, we showed tha...

PLoS ONE, 2009

Orientation selectivity of primary visual cortical neurons is an important requisite for shape pe... more 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. When goggle rearing (GR) started at P16-P30, 2 weeks of GR induced a marked over-representation of the exposed orientation, and 2 more weeks of GR consolidated the altered orientation maps. GR that started later than P50, in turn, induced the under-representation of the exposed orientation. Orientation plasticity in the most sensitive period was markedly suppressed by cortical infusion of NMDAR antagonist. The present study reveals that the plasticity and consolidation of orientation selectivity in an early life are dynamically regulated in an experience-dependent manner.

Neuroscience Research, 2006

In the visual cortex, pinwheel centers, which appear as point singularities in orientation maps, ... more 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. This tendency was mathematically analyzed with a formula describing the condition determining the geometrical relationship between pinwheel centers and ocular dominance columns. Moreover, to examine the effect of activity correlations in the eye-specific pathways on the column formation, we conducted intrinsic signal optical imaging using normally reared cats and dark-reared cats. The between-eye activity correlation in dark-reared cats is expected to be lower than that in normal cats due to the lack of common visual input in the two eyes. The statistical analysis of experimental data showed that while more pinwheel centers tended to be located in the center subregion of ocular dominance columns than in the border subregion in the normal cats, a weak tendency in the opposite direction was found in the dark-reared cats. Based on the consistent results from the model and experiment, it is suggested that the activity correlation between the left- and right-eye specific pathways has influence on the establishment of geometrical relationship in the cortical representation between orientation preference and ocular dominance.

Neuroscience Research, 2007

Neuroscience Research, 2009

Neurocomputing, 2013

One of the potential foundations for the perception of harmony is the neurons in the primary audi... more One of the potential foundations for the perception of harmony is the neurons in the primary auditory cortex (A1) that specifically respond to harmonically related frequencies, whose underlying organizing principles are yet unclear. We hypothesize that such harmony-related responses result from adapting to natural harmonic sounds by using sparse coding, a computational model that originally related natural image statistics to the neural properties of the primary visual cortex (V1). Our previous work has shown that a set of harmonic responses found in A1 of marmoset monkeys can emerge by sparse coding of highly harmonic sounds; however, the work was only preliminary because the specific sounds we used were unfamiliar to monkeys. In the present study, we recorded voices of marmosets, and showed that the same model applied to the conspecific vocalizations can reproduce the harmonyrelated responses. This result more directly supports the hypothesis that A1 adapts to natural sounds, in particular voices comprising harmonic overtones, under the principle of sparse coding.

Journal of Physical Therapy Science, 2011

... HIROKAZU NARITA, RPT, MSE1,2), HIDEKI YOSHIDA, RPT, PhD1), SHOJI CHIBA, PhD3), ATSUSHI ODA, R... more ... HIROKAZU NARITA, RPT, MSE1,2), HIDEKI YOSHIDA, RPT, PhD1), SHOJI CHIBA, PhD3), ATSUSHI ODA, RPT, PhD1), TAKAAKI ISHIKAWA, RPT4,6 ... We defined the line connecting the fibular head and the lateral malleolus as the reference line and drew a line perpendicular to ...

Journal of Neuroscience Methods, 2007

To examine the effect of experience on the developmental plasticity of functional maps in the vis... more 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. By this method, combined with the intrinsic signal optical imaging technique, we were able to observe a rapid and robust reorganization of orientation maps.

Journal of Neurophysiology, 2002

Neuronal activity in the early visual cortex has been extensively studied from the standpoint of ... more 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. The aim of the present study was to obtain a better understanding of the distribution of such neurons in the visual cortex. Using optical imaging of intrinsic signals, we found that there are a group of surface-responsive regions located in area 18, along the area 17/18 border, that tend to overlap the singular points of the orientation-preference map. Extracellular recordings confirmed that neurons responsive to uniform plane stimuli are accumulated in these regions. Such neurons also existed outside the surface-responsive regions around the singular points. These results suggest that there exists a functional organization related to the representation of a uniform surface in the early visual cortex.

Journal of Neural Engineering, 2009

Recently, intrinsic signal optical imaging has been widely used as a routine procedure for visual... more 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 microelectrode array for the ICMS was inserted with a specially designed easy-to-detach electrode holder around the 17/18 transition zones (TZs), where the left and right hemispheres were interconnected via the corpus callosum. The microelectrode array was stably anchored in agarose without any holder, which enabled us to visualize evoked activities even in the vicinity of penetration sites as well as in a wide recording region that covered a part of both hemispheres. The VSD imaging could successfully visualize ICMS-evoked excitation and subsequent propagation in the visual cortices contralateral as well as ipsilateral to the ICMS. Using the orientation maps as positional references, we showed that the activity propagation patterns were consistent with previously reported anatomical patterns of intracortical and interhemispheric connections. This finding indicates that our experimental system can serve for the investigation of cortical functional connectivity.

Frontiers in Neuroanatomy, 2011

2 branches, axon arborizations in layer III/IV were just below to layer Ia ramifications, but muc... more 2 branches, axon arborizations in layer III/IV were just below to layer Ia ramifications, but much wider (148-533 μm: mean, 341 μm) than that in layer Ia axon branches and dendritic bundles, suggesting that layer-specific information transmission spacing existed even from the same single axons from the AV to the GRS. Thus, microcolumn-type structure in the upper layer of the GRS was not strictly continuous from layer I to layer IV. How each layer and its components interact each other in different spatial scale should be solved future.

European Journal of Neuroscience, 2012

In an early stage of the postnatal development of cats, orientation maps mature and spatial frequ... more 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. Independent of age, an anteroposterior gradient of response strengths from lower to higher spatial frequencies was observed. This indicates that the regional distribution of spatial frequencies is innately determined. The size of iso-orientation domains tended to decrease as the stimulus spatial frequency increased at every age examined. In contrast, orientation representation bias changed with age. In cats younger than 3 months, the cardinal (vertical and horizontal) orientations were represented predominantly over the oblique orientations. However, in young adult cats from 3 to 9 months old, the representation bias switched to predominantly oblique orientations. These age-dependent changes in the orientation representation bias imply that orientation maps continue to elaborate within postnatal 1 year with the consolidation of spatial frequency selectivity. We conclude that both intrinsic and mutual factors lead to the development of orientation maps and spatial frequency selectivity.

Altered sensory experience in early life often leads to remarkable adaptations so that humans and... more 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., the sharpness of tuning of single neurons in the primary visual cortex, is modified to match a particular environment. Specifically, neurons tuned to an experienced orientation in orientation-restricted animals show sharper orientation tuning than neurons in normal animals, whereas the opposite was true for neurons tuned to non-experienced orientations. This sharpened tuning appears to be due to elongated receptive fields. Our results demonstrate that restricted sensory experiences can sculpt the supranormal functions of single neurons tailored for a particular environment. The above findings, in addition to the minimal population response to orientations close to the experienced one, agree with the predictions of a sparse coding hypothesis in which information is represented efficiently by a small number of activated neurons. This suggests that early brain areas adopt an efficient strategy for coding information even when animals are raised in a severely limited visual environment where sensory inputs have an unnatural statistical structure.