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S Yamane

Publications and source records attributed to S Yamane.

At least 73 records · Page 4Linked to original sources
PubMed1988

What facial features activate face neurons in the inferotemporal cortex of the monkey?

Single neurons were recorded in the inferotemporal cortex (IT) of a monkey trained to discriminate three selected human faces from a large number of different faces. Neurons which were not responsive to non-face visual stimuli used in the task but were responsive to certain sets of faces were found in the gyrus of the IT. The correlation analysis between the quantified facial features and the responses has revealed that face neurons detect the combination of the distances between facial parts such as eyes, mouth, eyebrows, hair, and so on. One of the face neurons detected the combination of the degree that the forehead above the left eye covered with hair and the distance between the eyes and the mouth. The results of this analysis have given appropriate reason for naming the neurons as the face neurons.

Animals↗
PubMed1987

Inhibition of Streptococcus mutans glucosyltransferase by M-GTFI, a new inhibitor.

Two hundred strains of soil microorganisms were screened for the production of inhibitors of the glucosyltransferase activity of Streptococcus mutans strain, K1-R. The strain producing the greatest amount of inhibitor was one recently isolated in our laboratory. It has now been identified as a strain of Micromonospora narashinoensis on the basis of morphological and physiological studies. The inhibitor, M-GTFI, affects the glucosyltransferase that produces the water-insoluble glucan rather than that which produces the water-soluble glucan. Fuchsin-sulphite staining of the inhibitor after its purification by polyacrylamide gel electrophoresis indicates that it is probably an acidic substance. It had Mr 5700 as was determined by gel filtration. From an examination of the effects of this inhibitor on representative strains of S. mutans other than K1-R, there is a suggestion of a similar selectivity for the water-insoluble glucan-forming activity in other strains.

Dental Caries↗
PubMed1986

Stereoscopic mechanisms: binocular responses of the striate cells of cats to moving light and dark bars.

New knowledge concerning the internal structure and response properties of the receptive fields of striate cells calls for a fresh appraisal of their binocular interactions in the interest of a better understanding of the neural mechanisms underlying binocular depth discrimination. Binocular position-disparity response profiles were recorded from 71 simple and B-cells in response to moving light and dark bars. Predominantly excitatory (PE) cells (N = 48) had disparity response profiles that were spatially closely similar to their respective monocular responses. In addition, the centrally located excitatory subregions were flanked on one or both sides by non-specific inhibitory regions. PE cells with a preferred stimulus orientation within 30 degrees of the vertical (N = 17) showed binocular facilitations with maximal values that were always more than twice (mean 3.3) the sum of the two monocular responses to the same stimuli and generally greater than the facilitations shown by cells with orientations more than 30 degrees from the vertical (N = 29; mean 2.2 times the sum of the respective monocular responses). The strength of the binocular facilitation depended on the stimulus contrast, the facilitation decreasing with increasing contrast. The receptive-field disparity distribution of the 31 PE cells capable of making significant horizontal disparity discriminations has standard deviations of 0.37 degrees and 0.40 degrees, respectively. Predominantly inhibitory cells (PI) (N = 23) showed two basic types of disparity response profile: symmetric (N = 17) and asymmetric (N = 6). Uncertainty regarding the precise location of the binocular fixation point in the anaesthetized and paralysed preparation made it difficult to categorize PI cells adequately.

Animals↗
PubMed1986

End-stopped cells and binocular depth discrimination in the striate cortex of cats.

Proposals concerning neural mechanisms for binocular depth discrimination have been criticized on the grounds that only striate cells with a preferred stimulus orientation not too far from the vertical can make significant horizontal disparity discriminations. We investigated this claim by preparing a two-dimensional array of position-disparity response profiles to moving light and dark bars from each of 18 cells in the simple family. From these arrays, it was possible to reconstruct disparity response profiles along any axis across the receptive field, irrespective of the cell's optimal stimulus orientation. This analysis showed that cells with a predominantly excitatory binocular response (N = 10) can make precise horizontal disparity discriminations, independent of their optimal stimulus orientation, provided that they are sufficiently end stopped. End-free cells, on the other hand, are effective for horizontal disparity discriminations only if their preferred orientation are near the vertical. Nearly all striate cells we examined were end-stopped to some degree and nearly half had an end inhibition sufficient to reduce the monocular response from the dominant eye to half its maximal amplitude. Cells having a predominantly inhibitory disparity response profile of the symmetric type (N = 8) have an inhibitory profile along every axis across the receptive field. An outline is given of a neural mechanism for the determination of absolute viewing distance based on the sensitivities of striate cells to vertical retinal-image disparities.

Animals↗
PubMed1986

Hornet venoms: lethalities and lethal capacities.

The i.v. LD50 values to mice of pure venoms of Vespa mandarinia japonica, V. simillima xanthoptera, V. tropica deusta and V. l. luctuosa were, respectively, 4.1, 3.1, 2.8 and 1.6 mg/kg. The LD50 value of 1.6 mg/kg distinguishes the venom of V. luctuosa as the most lethal known wasp venom. To measure the absolute lethality of a single sting, a new index, called lethal capacity, based on the amount of venom possessed by an individual and its lethality is presented. V. mandarinia and V. tropica are the most venomous known insects, with a lethal capacity of one sting from V. mandarinia delivering an LD50 (i.v.) dosage of venom to 270 g of mouse. The lethal capacity for an entire hornet colony, called colony lethal capacity, for V. tropica is 84 kg of mouse/colony.

Animals↗
PubMed1985

Properties of end-zone inhibition of hypercomplex cells in cat striate cortex.

The response properties of 96 striate cells in anaesthetized and paralyzed cats were examined by using narrow optimally-oriented light bars moved in the preferred direction at optimal velocity. The bar was lengthened systematically at both ends to plot and analyze bilateral length-response curves. We found a linear relationship between the maximum slope of the inhibitory phase of the curve and the strength of the end-zone inhibition for both cell families: simple and B-cells. This observation indicates that the length of the two end-zones as given by a bilateral length-response curve is approximately constant regardless of the strength of the end-zone inhibition for a change in the strength of the inhibition from 10 to 100%.

Animals↗
PubMed1985

Direction selectivity of simple cells in cat striate cortex to moving light bars. II. Relation to moving dark bar responses.

The response properties of 84 simple striate cells in anaesthetized (N2O/O2 supplemented with sodium pentobarbital) and paralyzed cats were examined quantitatively using narrow optimally-oriented light and dark bars moving at optimal velocities. Different cells gave two to five spatially-offset response peaks, the light bar and the dark bar response peaks alternating with one another. With only 5 exceptions, the cells had the same preferred direction for movement of the dark bar as for the light bar. Static-field plots were prepared from 32 of the 84 cells using stationary flashing bars. The receptive fields of different cells had from two to four subregions responding either at light on (ON subregion) or at light off (OFF subregion) although one cell had only a single subregion. In the preferred direction of stimulus movement cells gave either the same number of response peaks to moving bars as there were subregions or one additional response peak. The additional response peak, termed a boundary response, always occurred at the end of the sequence of response peaks and was always completely direction selective. The direction selectivities of the individual response peaks in the responses from 49 of the 84 cells were analyzed. To ensure that each response peak and the corresponding peak in the opposite direction both came from the same subregion, the 49 cells were selected on the basis of having a response in the nonpreferred direction sufficient for analysis and of having a stimulus velocity less than 2.5 degrees/s so as to avoid significant spatial shifts of the peaks due to response latencies. For all but two of the 49 cells, the response peaks in any given profile always showed a progressively greater degree of direction selectivity as the stimulus advanced from one subregion to the next, the first subregion giving the least directionally-selective response peak and the last subregion the most directionally-selective peak. This observation was independent of the direction of stimulus motion and of the particular sequence in which the ON and the OFF subregions were traversed by the stimulus. The response patterns observed experimentally have been correlated with theoretical response patterns based on the responses of lateral geniculate neurons.

Animals↗
PubMed1985

Simple and B-cells in cat striate cortex. Complementarity of responses to moving light and dark bars.

This report is based on the quantitatively recorded responses of 72 striate cells in the simple (S and SH) and B-cell (B and BH) families to narrow (0.14 degrees) moving light and dark bars. Cells were regarded as hypercomplex (SH and BH) if the end-zone inhibition reduced the response to 50% of its peak value. The contrast of the bars was relatively low and matched to be equal but opposite for the two kinds of bar. Average response histograms to the two kinds of bar were recorded separately and only subsequently combined. The response histogram from a given S- or SH-cell shows separate response peaks to the light and dark bars. The number of peaks varies from two to five in different cells. Cells with two response peaks were encountered most commonly (54%), and rather less common were cells with three (31%), four (7.5%), and five (7.5%) peaks. By defining the sequence of the response peaks according to the direction preferred by a moving light bar, the number of distinct spatial patterns of responses to the moving bars increases from four to eight since the first response in the sequence can be either to a light bar or to a dark bar. Examples of all eight responses have been recorded. For cells in the simple family with two response peaks, as well as for B-cells, the width of the light-bar peak was the same as, or closely similar to, that of the dark-bar peak. For S- and SH-cells with more than two response peaks this was also true for the two principal peaks, namely the largest and the next-largest immediately adjacent peak. In the simple family, the mean widths of the two principal response peaks remained closely similar despite the progressive decrease in their respective widths as the number of peaks in the pattern increased from two to five. The mean width of the two principal response peaks from S- and SH-cells (0.6 degrees) was significantly less than the mean width for B-cells (1.4 degrees). For simple-family cells the spatial overlap between the two principal peaks (mean 14%) was always less than 50% of the overall width of the two peaks, whereas for B-cells the overlap (mean 79%) was always greater than 50%. For cells in both the simple and B-cell families the length of the receptive field as given by a moving light bar is the same as that given by a moving dark bar.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Binocular simple cells for local stereopsis: comparison of receptive field organizations for the two eyes.

If a cell is to serve as a depth detector in a local stereopsis mechanism, it could indicate the depth of a specific object feature by responding only when that feature is located at the cell's preferred depth and being silent at other depths, the preferred depth varying from cell to cell over a small range. In order to assign a depth value to a particular object feature, the two receptive fields of the cell should respond to one and the same feature in the visual field. This can be done only if the organizations of the two receptive fields are identical or nearly so. Out of 31 cells in the simple family in the cat striate cortex, 15 were selected as having a monocular response from each eye sufficient to be able to examine their receptive field organizations in quantitative detail. The two receptive fields of each cell were remarkably similar in respect to the number, spatial sequence and position disparities of the response peaks to moving light and dark bars, as well as in respect to the relative ocular dominances, peak separations and direction selectivities of the response peaks to the two kinds of bar.

Action Potentials↗
PubMed1983

Neural interactions of two slits in the orientation domain in the visual cortical units of the cat.

The responses of the cat's visual cortical cells to an optimally oriented (O-) and an inclined (theta-) slit have been studied. Cell's responses to the simultaneous presentation, in simple cells, are similar to those to theta-slit alone, but in complex cells, are remarkably decreased at orientation difference of about 45 degrees. In the sequential presentation, the effects of preceding theta-slit on the responses to the following O-slit decrease as the orientation difference increases. This suggests that neural interactions of simultaneous and sequential presentation of two slits are caused by different mechanisms.

Animals↗