scholarly journals Distinctive characteristics of subclasses of red–green P-cells in LGN of macaque

1998 ◽  
Vol 15 (1) ◽  
pp. 37-46 ◽  
Author(s):  
MARTIN J.M. LANKHEET ◽  
PETER LENNIE ◽  
JOHN KRAUSKOPF
Keyword(s):  
Phase Difference ◽  
Color Space ◽  
Macaca Nemestrina ◽  
Large Field ◽  
Temporal Characteristics ◽  
Temporal Properties ◽  
Parvocellular Neurons ◽  
White Point ◽  
Chromatic Properties ◽  
P Cells

We characterized the chromatic and temporal properties of a sample of 177 red–green parvocellular neurons in the LGN of Macaca nemestrina, using large-field stimuli modulated along different directions through a white point in color space. We examined differences among the properties of the four subclasses of red–green P-cells (on- and off-center, red and green center). The responses of off-center cells lag the stimulus more than do those of on-center cells. At low temporal frequencies, this causes the phase difference between responses of the two kinds of cells to be considerably less than 180 deg. For isoluminant modulations the phases of on- and off-responses were more nearly 180 deg apart. A cell's temporal characteristics did not depend on the class of cone driving its center. Red center and green center cells have characteristically different chromatic properties, expressed either as preferred elevations in color space, or as weights with which cells combine inputs from L- and M-cones. Red center cells are relatively more responsive to achromatic modulation, and attach relatively more weight to input from the cones driving the center. Off-center cells also attach relatively more weight than do on-center cells to input from the class of cone driving the center.

scholarly journals Temporal-chromatic interactions in LGN P-cells

1998 ◽  
Vol 15 (1) ◽  
pp. 47-54 ◽  
Author(s):  
MARTIN J.M. LANKHEET ◽  
PETER LENNIE ◽  
JOHN KRAUSKOPF
Keyword(s):  
Temporal Frequency ◽  
Color Space ◽  
Three Dimensional ◽  
Linear Filter ◽  
Filter Model ◽  
Temporal Properties ◽  
Complex Interactions ◽  
Chromatic Properties ◽  
Almost All ◽  
P Cells

We studied the interaction between the chromatic and temporal properties of parvocellular (P) neurons in the lateral geniculate nucleus (LGN) of macaque monkeys. We measured the amplitudes and phases of responses to stimulation by spatially uniform fields modulated sinusoidally about a white point in a three-dimensional color space, at a range of temporal frequencies between 1 and 25 Hz. Below about 4 Hz, temporal frequency had relatively little effect on chromatic tuning. At higher frequencies chromatic opponency was weakened in almost all cells. The complex interactions between temporal and chromatic properties are represented by a linear filter model that describes response amplitude and phase as a function of temporal frequency and direction in color space along which stimuli are modulated. The model stipulates the cone inputs to center and surround, their temporal properties, and the linear combination of center and surround signals. It predicts the amplitudes and phases of responses of P-cells, and the change of chromatic properties with temporal frequency. We used the model to investigate whether or not the chromatic signature of the surround in a red–green cell could be estimated from the change in the cell's chromatic properties with temporal frequency. Our findings could be equally well described by mixed cone surrounds as by pure cone surrounds, and we conclude that, with regard to temporal properties, there is no benefit to be gained by segregating cone classes in center and surround.

Chromatic properties of neurons in macaque MT

1994 ◽  
Vol 11 (3) ◽  
pp. 455-466 ◽  
Author(s):  
Karl R. Gegenfurtner ◽  
Daniel C. Kiper ◽  
Jack M. H. Beusmans ◽  
Matteo Carandini ◽  
Qasim Zaidi ◽  
...  
Keyword(s):  
Contrast Sensitivity ◽  
Behavioral Contrast ◽  
Color Space ◽  
Contrast Threshold ◽  
High Contrast ◽  
Chromatic Contrast ◽  
Mt Neurons ◽  
Null Plane ◽  
Chromatic Properties ◽  
Almost All

AbstractWe have studied the responses of MT neurons to moving gratings, spatially modulated in luminance and chromaticity. Most MT neurons responded briskly and with high contrast sensitivity to targets whose luminance was modulated, with or without added chromatic contrast. When luminance modulation was removed and only chromatic stimulation was used, the responses of all MT neurons were attenuated. Most were completely unresponsive to stimulation with targets whose modulation fell within a “null” plane in color space; these null planes varied from neuron to neuron, but all lay close to the plane of constant photometric luminance. For about a third of the neurons, there was no color direction in which responses were completely abolished; almost all of these neurons had a definite minimum response for chromatic modulation near the isoluminant plane. MT neurons that responded to isoluminant targets did so inconsistently and with poor contrast sensitivity, so that only intensely modulated targets were effective. Whereas the best thresholds of MT neurons for luminance targets are close to behavioral contrast threshold, the thresholds for isoluminant targets lie considerably above behavioral contrast threshold. Therefore, although some MT neurons do give responses to isoluminant targets, they are unlikely to be the source of the chromatic motion signals revealed behaviorally.

Forest fire flame and smoke detection from UAV-captured images using fire-specific color features and multi-color space local binary pattern

2020 ◽  
Vol 8 (4) ◽  
pp. 285-309
Author(s):  
F.M. Anim Hossain ◽  
Youmin M. Zhang ◽  
Masuda Akter Tonima
Keyword(s):  
Computer Vision ◽  
Unmanned Aerial Vehicles ◽  
Forest Fire ◽  
Local Binary Pattern ◽  
Color Space ◽  
Fire Detection ◽  
Large Field ◽  
Aerial Vehicles ◽  
Aerial Platforms ◽  
Forest Fire Detection

In recent years, the frequency and severity of forest fire occurrence have increased, compelling the research communities to actively search for early forest fire detection and suppression methods. Remote sensing using computer vision techniques can provide early detection from a large field of view along with providing additional information such as location and severity of the fire. Over the last few years, the feasibility of forest fire detection by combining computer vision and aerial platforms such as manned and unmanned aerial vehicles, especially low cost and small-size unmanned aerial vehicles, have been experimented with and have shown promise by providing detection, geolocation, and fire characteristic information. This paper adds to the existing research by proposing a novel method of detecting forest fire using color and multi-color space local binary pattern of both flame and smoke signatures and a single artificial neural network. The training and evaluation images in this paper have been mostly obtained from aerial platforms with challenging circumstances such as minuscule flame pixels, varying illumination and range, complex backgrounds, occluded flame and smoke regions, and smoke blending into the background. The proposed method has achieved F1 scores of 0.84 for flame and 0.90 for smoke while maintaining a processing speed of 19 frames per second. It has outperformed support vector machine, random forest, Bayesian classifiers and YOLOv3, and has demonstrated the capability of detecting challenging flame and smoke regions of a wide range of sizes, colors, textures, and opacity.

Chromatic properties of neurons in macaque area V2

1997 ◽  
Vol 14 (6) ◽  
pp. 1061-1072 ◽  
Author(s):  
Daniel C. Kiper ◽  
Suzanne B. Fenstemaker ◽  
Karl R. Gegenfurtner
Keyword(s):  
Receptive Field ◽  
Single Cells ◽  
Sine Wave ◽  
Chromatic Contrast ◽  
Temporal Properties ◽  
Area V2 ◽  
Field Organization ◽  
Color Combinations ◽  
Chromatic Properties ◽  
Receptive Field Organization

AbstractWe recorded from single cells in area V2 of cynomolgus monkeys using standard acute recording techniques. After measuring each cell's spatial and temporal properties, we performed several tests of its chromatic properties using sine-wave gratings modulated around a mean gray background. Most cells behaved like neurons in area V1 and their responses were adequately described by a model that assumes a linear combination of cone signals. Unlike in V1, we found a subpopulation of cells whose activity was increased or inhibited by stimuli within a narrow range of color combinations. No particular color directions were preferentially represented. V2 cells showing color specificity, including cells showing narrow chromatic tuning, were present in any of the stripe compartments, as defined by cytochrome-oxidase (CO) staining. An addition of chromatic contrast facilitated the responses of most neurons to gratings with various luminance contrasts. Neurons in all three CO compartments gave significant responses to isoluminant gratings. Receptive-field properties of cells were generally similar for luminance and chromatically defined stimuli. We found only a small number of cells with a clearly identifiable double-opponent receptive-field organization.

Temporal Considerations in Analyzing and Designing Online Discussions in Education

2013 ◽  
pp. 198-231 ◽  
Author(s):  
Alyssa Friend Wise ◽  
Yuting Zhao ◽  
Simone Hausknecht ◽  
Ming Ming Chiu
Keyword(s):  
Data Aggregation ◽  
Online Discussions ◽  
Pedagogical Tool ◽  
Temporal Characteristics ◽  
Analysis And Design ◽  
Temporal Properties ◽  
Units Of Analysis ◽  
Temporal Aspects

Time plays a fundamental role in both the benefits and challenges of using online discussions as a pedagogical tool. This makes temporal considerations critical both for conducting analyses of how learning takes places through online discussions and for designing effective structures to support discussion activity. However, despite the importance of temporal considerations for online discussions, the majority of research on online discussions and guidance for design does not explicitly address issues of time. This chapter provides an initial foundation for researchers, designers, and instructors of online discussions to engage in temporally aware analysis and design. The authors begin with an overview of the general temporal characteristics of online discussions and the analytic considerations they raise in terms of timescales, data aggregation, and units of analysis. They then use the categories of Duration, Sequence, Pace, and Salience as a framework for unpacking the temporal aspects of online discussions in more detail, providing guidance for designers and instructors to manage temporal challenges and harness temporal opportunities. The authors conclude with a call for greater theorization of temporal properties, processes, and their effects on learning to support more informed analysis and design of online discussions.

Temporal properties of optic flow responses in the ventral intraparietal area

2002 ◽  
Vol 19 (3) ◽  
pp. 381-388 ◽  
Author(s):  
S.F. GABEL ◽  
H. MISSLISCH ◽  
S.J. SCHAAFSMA ◽  
J. DUYSENS
Keyword(s):  
Response Latency ◽  
Optic Flow ◽  
Dorsal Stream ◽  
Early Response ◽  
Stimulus Onset ◽  
Late Response ◽  
Temporal Characteristics ◽  
Temporal Properties ◽  
Mst Neurons ◽  
Ventral Intraparietal Area

The ventral intraparietal area (VIP) is located at the end of the dorsal stream. Its neurons are known to have receptive-field characteristics similar to those of MT and MST neurons, but little is known about the temporal characteristics of VIP cells' responses. How fast are directionally selective responses evoked in the ventral intraparietal area after viewing optic flow patterns, and what are the temporal properties of these neuronal responses? To examine these questions, we recorded the activity of 37 directionally selective ventral intraparietal area (VIP) neurons in two awake macaque monkeys in response to optic flow stimuli with presentation times ranging from 17 ms to 2000 ms. We found a minimum response latency of 45 ms, and a median latency of 152 ms. Of all neurons, 10% showed early response components only (response latency < 150 ms and no activity in 500–2000 ms interval after stimulus onset), 55% only late response components (response latency >150 ms and sustained activity in 500–2000 ms interval), and 35% both early and late response components. Early responses appeared to very brief stimulus presentations (33-ms duration), while the late responses required longer stimulus durations. The directional selectivity was independent of optic flow duration in all cells. These results suggest that only a subset of neurons in area VIP may contribute to the fast processing of optic flow, while showing that the temporal properties of VIP responses clearly differ from the temporal characteristics of neurons in areas MT and MST.

Spectral coding in cat retinal ganglion cell receptive fields

1986 ◽  
Vol 55 (2) ◽  
pp. 320-330 ◽  
Author(s):  
J. L. Ringo ◽  
M. L. Wolbarsht
Keyword(s):  
Ganglion Cell ◽  
Receptive Fields ◽  
Spatial Vision ◽  
Threshold Level ◽  
Large Field ◽  
Cone Type ◽  
Spectral Coding ◽  
Color Opponency ◽  
Opponent Color ◽  
Chromatic Properties

We have examined the spectral-coding properties of ganglion cell receptive fields in the cat retina. Two classes of spectral coding were found. The first class consists of cells in which color opponency is spatially local. That is, the opponent cone types cover the same (center or surround) region of the receptive field. The second class consists of cells that show color opponency only to large stimuli (relative to center diameter). Center and surround regions of cells of this class have different spectral sensitivities. Individually the regions are nonopponent. When both regions are stimulated, a spectral opponency is revealed. For example, we recorded from one unit in which the ON-center was mediated by the 556-nm cone type and the OFF-surround was mediated by both 450- and 556-nm cone types. Large-field, threshold-level stimulation in the short-wavelength end of the spectrum produced OFF-responses, while in the long-wavelength end produced ON-responses. For a small stimulus, cells of the second class could mediate spatial vision, largely unaffected by the chromatic properties of the stimulus. Cells of the second class (center/surround opponent) were more commonly encountered than cells of the first class (locally opponent). Color-opponent units of X, Y, and W types were all found.

scholarly journals Temporal characteristics of neural sensitivities to the interaural phase difference in the inferior colliculus

2002 ◽  
Vol 23 (5) ◽  
pp. 286-286
Author(s):  
Shigeto Furukawa ◽  
Katuhiro Maki ◽  
Makio Kashino ◽  
Hiroshi Riquimaroux ◽  
Tatsuya Hirahara
Keyword(s):  
Inferior Colliculus ◽  
Phase Difference ◽  
Temporal Characteristics ◽  
Interaural Phase ◽  
Interaural Phase Difference

Methodology for Improving Data Warehouse Design using Data Sources Temporal Metadata

2011 ◽  
pp. 231-251
Author(s):  
Francisco Araque ◽  
Alberto Salguero ◽  
Cecilia Delgado
Keyword(s):  
Data Warehouse ◽  
Data Extraction ◽  
Temporal Integration ◽  
Extraction Methods ◽  
Data Sources ◽  
Multiple Sources ◽  
Temporal Characteristics ◽  
Temporal Properties ◽  
Single Data ◽  
Using Data

One of the most complex issues of the integration and transformation interface is the case where there are multiple sources for a single data element in the enterprise Data Warehouse (DW). There are many facets due to the number of variables that are needed in the integration phase. This chapter presents our DW architecture for temporal integration on the basis of the temporal properties of the data and temporal characteristics of the data sources. If we use the data arrival properties of such underlying information sources, the Data Warehouse Administrator (DWA) can derive more appropriate rules and check the consistency of user requirements more accurately. The problem now facing the user is not the fact that the information being sought is unavailable, but rather that it is difficult to extract exactly what is needed from what is available. It would therefore be extremely useful to have an approach which determines whether it would be possible to integrate data from two data sources (with their respective data extraction methods associated). In order to make this decision, we use the temporal properties of the data, the temporal characteristics of the data sources, and their extraction methods. In this chapter, a solution to this problem is proposed.

The Ultrastructure of Monkey Gingival Epithelium

1967 ◽  
Vol 25 ◽  
pp. 16-17
Author(s):  
C.N. Sun
Keyword(s):  
Epithelial Cells ◽  
Macaca Nemestrina ◽  
Stratum Granulosum ◽  
Solution Ph ◽  
Gingival Epithelial Cells ◽  
Stratum Spinosum ◽  
Cell Layers ◽  
Gingival Epithelium ◽  
The Individual ◽  
Different Thickness

The present study demonstrates the ultrastructure of the gingival epithelium of the pig tail monkey (Macaca nemestrina). Specimens were taken from lingual and facial gingival surfaces and fixed in Dalton's chrome osmium solution (pH 7.6) for 1 hr, dehydrated, and then embedded in Epon 812.Tonofibrils are variable in number and structure according to the different region or location of the gingival epithelial cells, the main orientation of which is parallel to the long axis of the cells. The cytoplasm of the basal epithelial cells contains a great number of tonofilaments and numerous mitochondria. The basement membrane is 300 to 400 A thick. In the cells of stratum spinosum, the tonofibrils are densely packed and increased in number (fig. 1 and 3). They seem to take on a somewhat concentric arrangement around the nucleus. The filaments may occur scattered as thin fibrils in the cytoplasm or they may be arranged in bundles of different thickness. The filaments have a diameter about 50 A. In the stratum granulosum, the cells gradually become flatted, the tonofibrils are usually thin, and the individual tonofilaments are clearly distinguishable (fig. 2). The mitochondria and endoplasmic reticulum are seldom seen in these superficial cell layers.

Sign in / Sign up

Export Citation Format

Share Document