The perception of speed is influenced by visual contrast. In primary visual cortex (V1), an early stage in the visual perception pathway, the neural tuning to speed is directly related to the neural tuning to temporal frequency of stimulus changes. The influence of contrast on speed perception can be caused by the joint dependency of neural responses in V1 on temporal frequency and contrast. Here, we investigated how tuning to contrast and temporal frequency in V1 of anesthetized mice are related. We found that temporal frequency tuning is contrast-dependent. V1 was more responsive at lower temporal frequencies than the dLGN, consistent with previous work at high contrast. The temporal frequency tuning moves toward higher temporal frequencies with increasing contrast. The low half-maximum temporal frequency does not change with contrast. The Heeger divisive normalization equation provides a good fit to many response characteristics in V1, but does not fit the dependency of temporal frequency and
ABCO Automation signed a value-added reseller agreement with Visual Components, a company specializing in 3-D manufacturing factory simulation software. With this partnership, ABCO adds Visual Components simulation software to its service offerings.. As part of our concepting and designing process, we use Visual Components to provide clients a digital 3D model of their potential system, says Jack Walsh, executive vice president, ABCO Automation. Visual Components is key to helping our clients visualize the design and layout configuration as well as simulate the designs functionality.. The Visual Components software allows user to simulate the design of factory layouts; users get an approximate graphical view of a factory or production line, while the simulation function creates an accurate version of the factory or production line. With the visualization, users can test the simulation and find flaws before finalizing the design. ...
Over successive stages, the visual system develops neurons that respond with view, size and position invariance to objects or faces. A number of computational models have been developed to explain how transform-invariant cells could develop in the visual system. However, a major limitation of computer modelling studies to date has been that the visual stimuli are typically presented one at a time to the network during training. In this paper, we investigate how vision models may self-organize when multiple stimuli are presented together within each visual image during training. We show that as the number of independent stimuli grows large enough, standard competitive neural networks can suddenly switch from learning representations of the multi-stimulus input patterns to representing the individual stimuli. Furthermore, the competitive networks can learn transform (e.g. position or view) invariant representations of the individual stimuli if the network is presented with input patterns containing
Short presentation of a large moving pattern elicits an Ocular Following Response (OFR) that exhibits many of the properties attributed to low-level motion processing such as spatial and temporal integration, contrast gain control and divisive interaction between competing motions. Similar mechanisms have been demonstrated in V1 cortical activity in response to center-surround gratings patterns measured with real-time optical imaging in awake monkeys. More recent experiments of OFR have used disk gratings and bipartite stimuli which are optimized to study the dynamics of center-surround integration. We quantified two main characteristics of the global spatial integration of motion from an intermediate map of possible local translation velocities: (i) a finite optimal stimulus size for driving OFR, surrounded by an antagonistic modulation and (ii) a direction selective suppressive effect of the surround on the contrast gain control of the central stimuli [Barthelemy06,Barthelemy07].In fact, the ...
A computer-implemented image processing method and apparatus for warping a plurality of gel electrophoresis images is provided. The method includes the steps of assigning tiepoints in a reference image and in one or more object images. The tiepoints in the object image are evaluated one-by-one by comparison to regions about a corresponding tiepoint in the reference image, and the location of the tiepoint in the object image is adjusted by slight movement to a location with respect to recognizable features in both the reference and object image thereby defining a tiepoint pair linking a location in the reference image with a location in the object image. outlier tiepoint pairs may be rejected if that pair does not meet predetermined conditions. Warping functions are generated and then globally optimized. The plurality of images are tied together using the tiepoint pairs such that all of the images may be subsequently warped into registration to a single base image selected from the plurality of
It is almost one hundred years since Titchener [E.B. Titchener, Lectures on the Elementary Psychology of Feeling and Attention, Macmillan, New York, 1908] published his influential claim that attending to a particular sensory modality (or location) can speed up the relative time of arrival of stimuli presented in that modality (or location). However, the evidence supporting the existence of prior entry is, to date, mixed. In the present study, we used an audiovisual simultaneity judgment task in an attempt to circumvent the potential methodological confounds inherent in previous research in this area. Participants made simultaneous versus successive judgment responses regarding pairs of auditory and visual stimuli at varying stimulus onset asynchronies (SOAs) using the method of constant stimuli. In different blocks of trials, the participants were instructed to attend either to the auditory or to the visual modality, or else to divide their attention equally between the two modalities. The probability
Computer simulations of layers I and II of pirifonn (olfactory) cortex indicate that this biological network can generate a series of distinct output responses to individual stimuli, such that different responses encode different levels of information about a stimulus. In particular, after learning a set of stimuli modeled after distinct groups of odors, the simulated networks initial response to a cue indicates only its group or category, whereas subsequent responses to the same stimulus successively subdivide the group into increasingly specific encoding of the individual cue. These sequences of responses amount to an automated organization of perceptual memories according to both their similarities and differences, facilitating transfer of learned information to novel stimuli without loss of specific information about exceptions. Human recognition performance robustly exhibits such multiple levels: a given object can be identified as a vehicle, as an automobile, or as a Mustang. The findings ...
Integrated imaging and GPS network monitors remote object movement. Browser interface displays objects and detectors. Database stores object position movement. Cameras detect objects and generate image signal. Internet provides selectable connection between system controller and various cameras according to object positions.
Integrated imaging and GPS network monitors remote object movement. Browser interface displays objects and detectors. Database stores object position movement. Cameras detect objects and generate image signal. Internet provides selectable connection between system controller and various cameras according to object positions.
In the sustained readiness task (SRT) subjects are required to monitor the succession of presentations of a simple stimulus (red square) and respond as fast as possible at each stimulus onset. The rather long and random inter-trial-intervals (ITI) and the absence of external stimulation other than the red square, make it difficult for the subject to stay alerted (Klemmer, 1957). As such, response latencies are known to increase with fatigue and sedative effects.. The SRT task is only asking for a simple response to each appearance of the same red square without the need to discriminate between different stimuli (Donders, 1969). The SRT task is focusing on decrease in response speed when subjects monitor a simple unpredictable stimulus over an extended period of time. In contrast, vigilance tasks focus primarily on the decrement of discriminating between signal and noise (Davies & Parasuraman, 1982).. The sustained readiness task is an alternative way to measure the concept of sustained ...
A method of manufacturing a portable computing device, involves the steps of (1) maintaining a table comprising stimulus/response data for possible hardware components that may be interfaced in the computing device; (2) performing one manufacturing step in the manufacture of the portable computing device by interfacing one of the possible hardware components with one other component of the computing device; and (3) performing one other manufacturing step in the manufacture by: (i) applying a stimulus to the interfaced hardware component, and reading a response from the interfaced hardware component in response to the applied stimulus; (ii) identifying the interfaced hardware component from a correlation of the response with the stimulus/response data; and (iii) saving the identification as configuration data in the computing device.
Laurens son, Connor, has been struggling with reading and light sensitivity since pre-school. Lauren had Connor take a test to identify whether he had...
We show a hardness-preserving construction of a PRF from any length doubling PRG which improves upon known constructions whenever we can put a non-trivial upper bound qon the number of queries to...
Research in the Serre lab focuses on understanding the brain mechanisms underlying the recognition of objects and complex visual scenes using a combination of behavioral, imaging and physiological techniques.
There is a puzzle in the FAQ: Remove two opposite corners from a chessboard. Can you cover the remaining 62 squares with dominoes? Answer: No. The remaining board has 32 white and 30 black squares, but each domino must cover one black and one white square. The 56 tiles in a set of Triominoes cannot make a convex shape due to parity. Joseph DeVincentis explains why. Sam Loyd invented the 15-14 puzzle. He offered $1000 to the first person to find a sequence of moves which put at the pieces in order. By parity, this problem was unsolvable. To see this, draw a 3x3 grid and place different objects on a1, a2, c1, and c2. Make moves with the following rule: When one object moves, a different object must move to take its place. Moves are thus paired. Now, swap the objects on a1 and a2. You will find this is possible, but only if the objects on c1 and c2 also swap. John Conway made a block packing problem. You must fit three 1x1x3 boxes, thirteen 1x2x4 boxes, one 1x2x2 box, and one 2x2x2 cube into a ...
GO:0007601. The series of events required for an organism to receive a visual stimulus, convert it to a molecular signal, and recognize and characterize the signal. Visual stimuli are detected in the form of photons and are processed to form an image. ...
Across the entire dataset of 10 decoding sessions per animal, the 50 object conditions could be decoded from the planning epoch with an accuracy of 48.7 ± 3.6 and 51.9 ± 3.4% (mean ± SD) in animals M and Z, respectively. This performance was 23.9× and 26× above chance (2%). During motor execution (i.e., from the hold epoch), the average decoding accuracy was even larger: 62.9 ± 3.6 and 61.4 ± 4.1% (monkeys M and Z, respectively), corresponding to 31.5× and 30.7× above chance (2%). This means that decoding accuracy in the hold epoch was on average 14.2 and 9.5 percentage points higher than in the planning epoch (animals M and Z, respectively). This improvement was significant (p , 0.001, two-way ANOVA) in both animals.. Furthermore, we explored the functional differences of the various cortical areas and recording sites separately in each electrode array: (1) F5lat; (2) F5med; (3) AIPlat; (4) AIPmed; (5) M1lat; and (6) M1med (array numbering as in Fig. 2). To make the analysis fair, we ...
Assayed all keys except for J23202, but Tecan was being wierd and wouldnt give good numbers even though I changed both the integration time and the gain like 20 times. The following results were taken at a gain of 180 and 200 with the max integration time, and the OnRFP is still only in the 1000s rather than the 10000s. Might want to repeat this assay sometime ...
http://phygeo7.geo.uni-augsburg.de/gis2/scripts/v.digatt v.digatt] (shell script) Interactively assign numeric table attributes to series of vector objects. It is meant to be effective by avoiding to type in the attribute value for all single objects again and again. The user is prompted for typing in an attribute value which is assigned to all objects selected by mouseclick afterwards. Next the display is redrawn after updating the table column. Zooming allows to change the region before the old value can be reused or a new one can be typed in (or copied by mouse from another object) in order to assign it to the next series of objects etc. It is tested not very extensively yet. Therefore better work with a copy of your map and consider using v.digit or d.what.vect -e alternatively. [http://phygeo7.geo.uni-augsburg.de/gis2/scripts/v.digatt.png screenshot ...
v.digatt (shell script) Interactively assign numeric table attributes to series of vector objects. It is meant to be effective by avoiding to type in the attribute value for all single objects again and again. The user is prompted for typing in an attribute value which is assigned to all objects selected by mouseclick afterwards. Next the display is redrawn after updating the table column. Zooming allows to change the region before the old value can be reused or a new one can be typed in (or copied by mouse from another object) in order to assign it to the next series of objects etc. It is tested not very extensively yet. Therefore better work with a copy of your map and consider using v.digit or d.what.vect -e alternatively. screenshot ...
The API Im trying to describe has a structure where the root object can contain an arbitrary number of child objects (properties that are themselves objects). The key, or property in the root object, is the unique identifier of the child object, and the value is the rest of the child objects data.. ...
An event is an occurrence of a phenomenon at a certain moment in time. The occurrence of the event itself is assumed to have no duration. Typically, when an event occurs, it affects the state of an object. A state machine is a model of the behaviour of a single object over time and helps you to understand how that objects state affects its reactions to events.. Figure 18 shows a state machine diagram (known as a statechart diagram in the UML) relating to the occupancy of a room in a hot ...
Gene target information for LOC340089 - POM121 membrane glycoprotein (rat) pseudogene (human). Find diseases associated with this biological target and compounds tested against it in bioassay experiments.
Gene target information for Gnptg - N-acetylglucosamine-1-phosphotransferase, gamma subunit (house mouse). Find diseases associated with this biological target and compounds tested against it in bioassay experiments.
ED Eliminator Review Is ED Eliminator Scam Or Not? Jack Stonewood ED Eliminator System Does Really Works? Check My First ED Eliminator Bonus & Results
This document provides the function overview, relationships between tables, description of single objects, description of MIB tables, and description of alarm objects.
A seller designs a mechanism to sell a single object to a potential buyer whose private type is his incomplete information about his valuation. The seller can ...
When you view your stress response as helpful, you create the biology of courage.. In other words, when you view stress as good, it is good. Not in a fake way. It actually changes how your body responds.. McGonigal shares a study where researchers tracked 30,000 adults for eight years. At the start of the study, they asked participants whether they believed that stress is harmful to your health.. What they found at the end of the study is that 43% had an increased chance of dying from stress, only if they believed that stress was harmful to your health.. What they found is that re-thinking the stress response as helpful helps people to be less anxious, less stressed out, and more confident.. Normally, in a stress response, your heart rate goes up and your blood vessels restrict. But when you view your stress response as helpful, your physical response changes. Your blood vessels stay relaxed, like they do in in moments of joy and courage.. And this difference, McGonigal says, is the difference ...
The new SQL Server 2012 Sequence Object can be used to generate unique numbers that can be automatically incremented based on an increment value. Greg Larsen discusses the different features of the sequence object and how you can use it to generate sequence numbers.
Sadly, the Bitcoin system does not allow me to see who is sending me bitcoin donations, so I cannot thank you personally. I must thank you all collectively here. Thank you for your kind support of our work ...
Need the ability to add objects to the list with the default value equal for all. This value can ... it was expected that both values will be other.
Construct a new path object for use with path based webservice. The path is immediately validated before use, so any subclass constraints that affect this path need to be included in the subtypes hash.. This constructor is not meant to be used directly; rather, obtain Webservice::InterMine:Path objects from their respective Service objects via their ...
In two experiments, magnetoencephalography (MEG) was used to investigate the effects of motion on gamma oscillations in human early visual cortex. When presented centrally, but not peripherally, stationary and moving gratings elicited several evoked and induced response components in early visual cortex. Time-frequency analysis revealed two nonphase locked gamma power increases-an initial, rapidly adapting response and one sustained throughout stimulus presentation and varying in frequency across observers from 28 to 64 Hz. Stimulus motion raised the sustained gamma oscillation frequency by a mean of approximately 10 Hz. The largest motion-induced frequency increases were in those observers with the lowest gamma response frequencies for stationary stimuli, suggesting a possible saturation mechanism. Moderate gamma amplitude increases to moving versus stationary stimuli were also observed but were not correlated with the magnitude of the frequency increase. At the same site in visual cortex, sustained
ABSTRACT. Aging often results in reduced visual acuity from changes in both the eye and neural circuits [1-4]. In normally aging subjects, primary visual cortex has been shown to have reduced responses to visual stimulation [5]. It is not known, however, to what extent aging affects visual field representations and population receptive sizes in human primary visual cortex. Here we use functional MRI (fMRI) and population receptive field (pRF) modeling [6] to measure angular and eccentric retinotopic representations and population receptive fields in primary visual cortex in healthy aging subjects ages 57 - 70 and in healthy young volunteers ages 24 - 36 (n = 9). Retinotopic stimuli consisted of black and white, drifting checkerboards comprising moving bars 11 deg in radius. Primary visual cortex (V1) was clearly identifiable along the calcarine sulcus in all hemispheres. There was a significant decrease in the surface area of V1 from 0 to 3 deg eccentricity in the aging subjects with respect to ...
Aging often results in reduced visual acuity from changes in both the eye and neural circuits [1-4]. In normally aging subjects, primary visual cortex has been shown to have reduced responses to visual stimulation [5]. It is not known, however, to what extent aging affects visual field repre-sentations and population receptive sizes in human primary visual cortex. Here we use func-tional MRI (fMRI) and population receptive field (pRF) modeling [6] to measure angular and ec-centric retinotopic representations and population receptive fields in primary visual cortex in healthy aging subjects ages 57 - 70 and in healthy young volunteers ages 24 - 36 (n = 9). Retinotopic stimuli consisted of black and white, drifting checkerboards comprising moving bars 11 deg in radius. Primary visual cortex (V1) was clearly identifiable along the calcarine sulcus in all hemispheres. There was a significant decrease in the surface area of V1 from 0 to 3 deg eccentricity in the aging subjects with respect to the young
Many pairs of spatial and temporal frequencies in a motion display that result in the same stimulus speed for a moving object can produce different speed percepts (Priebe NJ et al., J Neurosci. 2003, 23(13): 5650-61). We previously reported that judgments of the speed of an object depend on the spatiotemporal frequency of the moving pattern in an inverted-U function, peaking at a specific spatial and temporal frequency combination [http://www.journalofvision.org/4/8/84/]. The location of this peak is largely independent of the size and shape of the object. In the present series of experiments, with the use of high coherence dot motion stimuli, we investigated the dependence of perceived speed on both spatial and temporal frequencies. The perceived speed of the stimulus was estimated using a 2AFC paradigm with interleaved QUEST staircases; subjects were asked to pick the faster of the two spatially separated [6 deg eccentricity] patches of dots moving in opposite directions. We systematically ...
In this study, we show that top-down control mechanisms engaged during visual imagery of simple shapes (letters X and O) can selectively activate position-invariant perceptual codes in visual areas specialised for shape processing, including lateral occipital complex (LOC). First, we used multivoxel pattern analysis (MVPA) to identify visual cortical areas that code for shape within a position-invariant reference frame. Next, we examined the similarity between these high-level visual codes and patterns elicited while participants imagined the corresponding stimulus at central fixation. Our results demonstrate that imagery engages object-centred codes in higher-level visual areas. More generally, our results also demonstrate that top-down control mechanisms are able to generate highly specific patterns of visual activity in the absence of corresponding sensory input. We argue that a general model of top-down control must account for dynamic modulation of functional connectivity between high-level control
The simple-cell receptive field (RF) structure is an attractive and unique feature of the primary visual cortex, which is thought to reflect the circuitry principles governing orientation selectivity. Synaptic inputs underlying spike RFs are key to understanding mechanisms for neuronal processing. The well-known push-pull model, which is proposed to explain the synaptic mechanism under simple-cell RFs, predicts that in simple cells the spatially separated excitation and inhibition does not interact with each other and that simple inhibitory neurons exist in the primary visual cortex (V1). However, previous experimental results suggest that synaptic inhibition plays an important role in shaping RF properties in the visual cortex. The synaptic mechanisms underlying simple-cell RFs remain not well understood, partly due to difficulties in systematically studying functional properties of cortical inhibitory neurons and precisely measuring excitatory and inhibitory synaptic inputs in vivo.; In the ...
TY - JOUR. T1 - Recording of reversed Uhthoffs phenomenon by visual evoked potentials elicited by pseudorandom binary sequence stimulation. AU - Mori, H.. AU - Kiyosawa, M.. AU - Nemoto, N.. AU - Mochizuki, M.. AU - Momose, K.. PY - 2001/1/1. Y1 - 2001/1/1. N2 - Reversed Uhthoffs phenomenon is a temporal improvement of visual acuity initiated by body cooling in subjects with demyelinating optic neuropathy. Up until the present, it has been difficult to demonstrate Uhthoffs phenomenon by visually evoked potentials (VEPs). We have been able to demonstrate this phenomenon with VEPs elicited by pseudorandom binary sequence stimuli (PRBS-VEP). Case 1 was a 50-year-old woman with right optic neuropathy. Her right visual acuity was 0.02 and improvement of subjective visual acuity, and temporal frequency characteristics of the VEPs were seen after ingestion of cold water. Case 2 was a 29-year-old man with right optic neuropathy and multiple sclerosis. His right visual acuity was 0.4 and the visual ...
Many current models of working memory (WM) emphasize a close relationship between WM and attention. Recently it was demonstrated that attention can be dynamically and voluntarily oriented to items held in WM, and it was suggested that directed attention can modulate the maintenance of specific WM representations. Here we used event-related functional magnetic resonance imaging to test the effects of orienting attention to a category of stimuli when participants maintained a variable number of faces and scenes in WM. Retro-cues that indicated the relevant stimulus type for the subsequent WM test modulated maintenance-related activity in extrastriate areas preferentially responsive to face or scene stimuli - fusiform and parahippocampal gyri respectively - in a categorical way. After the retro-cue, the activity level in these areas was larger for the cued category in a load-independent way, suggesting the modulation may also reflect anticipation of the probe stimulus. Activity in associative parietal and
© 2019 The Author(s) 2019. Published by Oxford University Press. All rights reserved. The primate visual system contains myriad feedback projections from higher-to lower-order cortical areas, an architecture that has been implicated in the top-down modulation of early visual areas during working memory and attention. Here we tested the hypothesis that these feedback projections also modulate early visual cortical activity during the planning of visually guided actions. We show, across three separate human functional magnetic resonance imaging (fMRI) studies involving object-directed movements, that information related to the motor effector to be used (i.e., limb, eye) and action goal to be performed (i.e., grasp, reach) can be selectively decoded-prior to movement-from the retinotopic representation of the target object(s) in early visual cortex. We also find that during the planning of sequential actions involving objects in two different spatial locations, that motor-related information can be
Previous experimental studies have reported that V1 neurons can respond to a region of uniform luminance (Kinoshita & Komatsu, 2001; Friedman et al., 2003; Roe et al., 2005). Some V1 neurons even show responses modulated by the luminance change of surrounding areas, or flankers that are several degrees away from the their CRFs, while the luminance of the area that covers their CRFs stays constant (Rossi et al., 1996; Rossi & Paradiso, 1999). Some of these neurons show responses that are antiphase to the luminance change of flankers, but show responses in-phase to direct luminance change. These responses are consistent with the human perception of brightness. The modulation of these neurons responses to the simultaneous contrast stimuli cut off at 4 Hz, while the modulation of their responses to direct luminance increases with temporal frequency of the luminance change, which is also consistent to the result shown in human psychophysical studies (Valois, Webster, Valois, & Lingelbach, 1986; ...
Our results provide the first evidence that temporal expectation modulates the power and coherence of gamma responses already at the earliest stage of cortical visual processing. It has been shown that the power and synchronization of gamma oscillations can be modulated by spatial and feature selective attention (Müller et al., 2000; Fries et al., 2001, 2008; Bichot et al., 2005; Taylor et al., 2005; Buschman and Miller, 2007). Our findings extend this notion to the temporal domain.. Fries et al. (2001, 2008) found that gamma synchronization in area V4 was stronger when attention was directed to a stimulus inside the RF. The expectation effects we found in V1 are of comparable magnitude as those found for spatial attention in V4. However, the effects of expectation in V1 are not confined to the attended location (here the fixation point), since the modulation in gamma was comparable for sites recorded simultaneously in the central and peripheral representations of the visual field. These ...
Visual cortex is traditionally viewed as a hierarchy of neural feature detectors, with neural population responses being driven by bottom-up stimulus features. Conversely, predictive coding models propose that each stage of the visual hierarchy harbors two computationally distinct classes of processing unit: representational units that encode the conditional probability of a stimulus and provide predictions to the next lower level; and error units that encode the mismatch between predictions and bottom-up evidence, and forward prediction error to the next higher level. Predictive coding therefore suggests that neural population responses in category-selective visual regions, like the fusiform face area (FFA), reflect a summation of activity related to prediction (face expectation) and prediction error (face surprise), rather than a homogenous feature detection response. We tested the rival hypotheses of the feature detection and predictive coding models by collecting functional magnetic resonance
Spike count correlations (SCCs), covariation of neuronal responses across multiple presentations of the same stimulus, are ubiquitous in sensory cortices and span different modalities (1⇓-3) and processing stages (4⇓⇓-7). In the visual system, SCCs, also termed noise correlations, have traditionally been considered to be independent of the stimulus and hence have been thought to impede stimulus encoding (8). Studies on stimulus-independent aspects of SCCs in the primary visual cortex (V1) sought to capture correlation patterns that were solely accounted for by differences in receptive field structure (9, 10). Initial investigations of dependence of SCCs on low-level stimulus features, such as orientation and contrast, focused on the population mean of SCCs (11⇓-13), but stimulus-dependent changes in the mean are modest in awake animals (9, 14). Only recently has orientation and contrast dependence of the fine structure of SCCs been demonstrated in anesthetized cats and awake mice (15). ...
A key attribute of the brain is its ability to seamlessly integrate sensory information to form a multisensory representation of the world. In early perceptual processing, the superior colliculus (SC) takes a leading role in integrating visual, auditory and somatosensory stimuli in order to direct eye movements. The SC forms a representation of multisensory space through a layering of retinotopic maps which are sensitive to different types of stimuli. These eye-centered topographic maps can adapt to crossmodal stimuli so that the SC can automatically shift our gaze, moderated by cortical feedback. In this paper we describe a neural network model of the SC consisting of a hierarchy of nine topographic maps that combine to form a multisensory retinotopic representation of audio-visual space. Our motivation is to evaluate whether a biologically plausible model of the SC can localize audio-visual inputs live from a camera and two microphones. We use spatial contrast and a novel form of temporal ...
During infancy, smart perceptual mechanisms develop allowing infants to judge time-space motion dynamics more efficiently with age and locomotor experience. This emerging capacity may be vital to enable preparedness for upcoming events and to be able to navigate in a changing environment. Little is known about brain changes that support the development of prospective control and about processes, such as preterm birth, that may compromise it. As a function of perception of visual motion, this paper will describe behavioral and brain studies with young infants investigating the development of visual perception for prospective control. By means of the three visual motion paradigms of occlusion, looming, and optic flow, our research shows the importance of including behavioral data when studying the neural correlates of prospective control ...
Orienting spatial attention to locations in the extrapersonal world has been intensively investigated during the past decades. Recently, it was demonstrated that it is also possible to shift attention to locations within mental representations held in working memory. This is an important issue, since the allocation of our attention is not only guided by external stimuli, but also by their internal representations and the expectations we build upon them. The present experiment used behavioural measures and event-related functional magnetic resonance imaging to investigate whether spatial orienting to mental representations can modulate the search and retrieval of information from working memory, and to identify the neural systems involved, respectively. Participants viewed an array of coloured crosses. Seconds after its disappearance, they were cued to locations in the array with valid or neutral cues. Subsequently, they decided whether a probe stimulus was presented in the array. The behavioural results
A large extent of the posterior cortex of the primate brain is devoted to vision, and it contains two general streams that process visual information. The one stream is situated more ventrally in the cortex and is important for object recognition, pattern recognition, color perception, and shape perception. These attributes of visual analysis we associate with visual awareness or seeing, and thus this stream has been referred to as the what system because it recognizes objects (Ungerleider and Mishkin 1982). A second, more dorsal stream is associated with visual-motor transformations-that is, the routing of sensory information into motor areas for the purpose of action. This dorsal stream plays an important role in attention, decisions, and movement planning. It also plays an important role in spatial awareness, which is crucial for planning movements to locations in space and for transforming visually defined locations into movement coordinates to accomplish accurate motor behaviors. This ...
In an attempt to understand how low-level visual information contributes to object categorisation, previous studies have examined the effects of spatially filtering images on object recognition at different levels of abstraction. Here, the quantitative thresholds for object categorisation at the basic and subordinate levels are determined by using a combination of the method of adjustment and a match-to-sample method. Participants were asked to adjust the cut-off of either a low-pass or high-pass filter applied to a target image until they reached the threshold at which they could match the target image to one of six simultaneously presented category names. This allowed more quantitative analysis of the spatial frequencies necessary for recognition than previous studies. Results indicate that a more central range of low spatial frequencies is necessary for subordinate categorisation than basic, though the difference is small, at about 0.25 octaves. Conversely, there was no effect of categorisation level
Objects that are semantically related to the visual scene context are typically better recognized than unrelated objects. While context effects on object recognition are well studied, the question which particular visual information of an objects surroundings modulates its semantic processing is still unresolved. Typically, one would expect contextual influences to arise from high-level, semantic components of a scene but what if even low-level features could modulate object processing? Here, we generated seemingly meaningless textures of real-world scenes, which preserved similar summary statistics but discarded spatial layout information. In Experiment 1, participants categorized such textures better than colour controls that lacked higher-order scene statistics while original scenes resulted in the highest performance. In Experiment 2, participants recognized briefly presented consistent objects on scenes significantly better than inconsistent objects, whereas on textures, consistent objects were
Stimulus modality, also called sensory modality, is one aspect of a stimulus or what we perceive after a stimulus. For example, the temperature modality is registered after heat or cold stimulate a receptor. Some sensory modalities include: light, sound, temperature, taste, pressure, and smell. The type and location of the sensory receptor activated by the stimulus plays the primary role in coding the sensation. All sensory modalities work together to heighten stimuli sensation when necessary. Multimodal perception is the ability of the mammalian nervous system to combine all of the different inputs of the sensory nervous system to result in an enhanced detection or identification of a particular stimulus. Combinations of all sensory modalities are done in cases where a single sensory modality results in ambiguous and incomplete result. Integration of all sensory modalities occurs when multimodal neurons receive sensory information which overlaps with different modalities. Multimodal neurons are ...
Visual images of our own and others body parts can be highly similar, but the types of information we wish to extract from them are highly distinct. From our own body we wish to combine visual information with, at least, somatosensory, proprioceptive and motor information in order to guide our interpretation of sensory events and our actions upon the world. For others bodies we only have visual information available, but from that we can derive much useful social information including their age, health, gender, emotional state and intentions. Consequently, a challenge for the brain is to sort visual images of our own bodies, to be integrated with processing from other sensory modalities, from highly similar images of others bodies for social cognition. We explored the possibility that the extrastriate body area (EBA) may help to accomplish this sorting. Previous work had suggested that the EBA is responsive to images of both our own and others body parts but does not distinguish between ...
Author Summary How can humans and animals make complex decisions on time scales as short as 100 ms? The information required for such decisions is coded in neural activity and should be read out on a very brief time scale. Traditional approaches to coding of neural information rely on the number of electrical pulses, or spikes, that neurons fire in a certain time window. Although this type of code is likely to be used by the brain for higher cognitive tasks, it may be too slow for fast decisions. Here, we explore an alternative code which is based on the latency of spikes with respect to a reference signal. By analyzing the simultaneous responses of many cells in monkey visual cortex, we show that information about the orientation of visual stimuli can be extracted reliably from spike latencies on very short time scales.
When objects disappear from view, we can still bring them to mind, at least for brief periods of time, because we can represent those objects in visual short-term memory (VSTM) (Sperling, 1960; Cowan, 2001). A defining characteristic of this representation is that it is topographic, that is, it preserves a spatial organization based on the original visual percept (Vogel and Machizawa, 2004; Astle et al., 2009; Kuo et al., 2009). Recent research has also shown that features or locations of visual items that match those being maintained in conscious VSTM automatically capture our attention (Awh and Jonides, 2001; Olivers et al., 2006; Soto et al., 2008). But do objects leave some trace that can guide spatial attention, even without participants intentionally remembering them? Furthermore, could subliminally presented objects leave a topographically arranged representation that can capture attention? We presented objects either supraliminally or subliminally and then 1 s later re-presented one of those
Neurite arbors of VGluT3-expressing amacrine cells (VG3-ACs) process visual information locally uniformly detecting object motion while varying in contrast preferences; and in spite of extensive overlap between arbors of neighboring cells population activity in the VG3-AC plexus encodes stimulus positions with subcellular precision.
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Hi there, Ive built a horizontally scrollable hbox layout container, docked on top, filled with other sub-containers, which I want to transform into a vbox layout (scrollable vertically, docked to the left) on orientation change. Right now Im doing something like this on resize: var hboxLayout = Ext.getCmp(hboxLayoutID); Ext.getCmp(hboxLayoutParentID).removeAll(false, true);
Amodal categorization is the grouping of common stimuli independent of the modality of sensory input. Primates show behavioural signs of amodal categorization/cross-modal equivalence. When provided with an object to inspect haptically, apes and monkeys were able to generalize what they had learned to the visual modality (Davenport & Rogers 1970; Weiskrantz & Cowey 1975; Elliot 1977). In addition, when monkeys (or humans) were expected to categorize vocalizations, prior presentation of conceptually congruent images led to faster responses (Martin-Malivel & Fagot 2001). This demonstrates an independence of the perceptual attributes of a stimulus to categorization, something that should be incorporated more explicitly in the aforementioned models of object categorization.. We do not yet know the neural basis for amodal processing, and, indeed, there may be biases for some stimulus pairings across modality that are innate or biased early in development, and therefore are not consistent with other ...
Categorization is a process by which the brain assigns meaning to sensory stimuli. Through experience, we learn to group stimuli into categories, such as chair, table and vehicle, which are critical for rapidly and appropriately selecting behavioural responses. Although much is known about the neural representation of simple visual stimulus features (for example, orientation, direction and colour), relatively little is known about how the brain learns and encodes the meaning of stimuli. We trained monkeys to classify 360° of visual motion directions into two discrete categories, and compared neuronal activity in the lateral intraparietal (LIP) and middle temporal (MT) areas, two interconnected brain regions known to be involved in visual motion processing. Here we show that neurons in LIP-an area known to be centrally involved in visuo-spatial attention, motor planning, and decision-making -- robustly reflect the category of motion direction as a result of learning. The activity of LIP ...
One strong claim made by the representational-hierarchical account of cortical function in the ventral visual stream (VVS) is that the VVS is a functional continuum: The basic computations carried out in service of a given cognitive function, such as recognition memory or visual discrimination, might be the same at all points along the VVS. Here, we use a single-layer computational model with a fixed learning mechanism and set of parameters to simulate a variety of cognitive phenomena from different parts of the functional continuum of the VVS: recognition memory, categorization of perceptually related stimuli, perceptual learning of highly similar stimuli, and development of retinotopy and orientation selectivity. The simulation results indicate-consistent with the representational-hierarchical view-that the simple existence of different levels of representational complexity in different parts of the VVS is sufficient to drive the emergence of distinct regions that appear to be specialized for ...
Simple features, such as particular edges of the image in a specific orientation, are extracted at the first cortical processing stage, called the primary visual cortex, or V1. Then subsequent cortical processing stages, V2, V4, etc., extract progressively more complex features, culminating in the inferotemporal cortex where that essential viewpoint invariant object identification is thought to occur. But, most of the connections in the human brain do not project up the cortical hierarchy, as might be expected from gross neuroanatomy, but rather connect neurons located at the same hierarchical level, called lateral connections, and also project down the cortical hierarchy to lower processing levels ...
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The body is designed in a way wherein the different sense organs work with the brain for the interpretation of the different senses so that we can exhibit the appropriate responses, both behavioral and motor. However, there are instances when the responses are not proper because of misinterpretation of the senses. This condition is called sensory processing disorder.. Sensory processing disorder (SPD) was formerly known as sensory integration dysfunction was first described by A. Jean Ayres, a neuroscientist who said that this disorder is similar to a traffic jam that occurs in the neurons, wherein some parts of the brain are prevented from receiving the correct information so that sensory information are interpreted correctly. For someone who has SPD, what happens is that sensory information is perceived differently from that which is normal to other people. This will then result in behavior or responses that are unusual, which makes it hard to accomplish some tasks.. The exact causes of ...
Stock photo Web sites (or any other Web sites that allow downloading high-quality pictures) list thousands of photos that include a single object on a white background. These can be pretty much anything-fruits, vegetables, hands, legs, lamps, tools, cookies, trees, cars, etc. Usually these photos are intended for image editing needs such as complex compositions, ads, and any other pictures that may include either a single object or more than one. But before using such objects in your composition, you want to remove that annoying white background. In this tutorial we will look at the quickest way to remove unwanted background of any color.. Please note that by the quickest way we really mean the quickest, not the most precise way (which is the theme for the next Pixelmator tutorial) of removing unwanted backgrounds. This technique might not work with complex backgrounds or blurry objects.. Anyway, lets get started.. Step 1. Open an image with the object for which you would like to remove the ...
A perceptual set, also called perceptual expectancy or just set is a predisposition to perceive things in a certain way.[73] It is an example of how perception can be shaped by top-down processes such as drives and expectations.[74] Perceptual sets occur in all the different senses.[45] They can be long term, such as a special sensitivity to hearing ones own name in a crowded room, or short term, as in the ease with which hungry people notice the smell of food.[75] A simple demonstration of the effect involved very brief presentations of non-words such as sael. Subjects who were told to expect words about animals read it as seal, but others who were expecting boat-related words read it as sail.[75]. Sets can be created by motivation and so can result in people interpreting ambiguous figures so that they see what they want to see.[74] For instance, how someone perceives what unfolds during a sports game can be biased if they strongly support one of the teams.[76] In one experiment, ...
A perceptual set, also called perceptual expectancy or just set is a predisposition to perceive things in a certain way.[90] It is an example of how perception can be shaped by top-down processes such as drives and expectations.[91] Perceptual sets occur in all the different senses.[56] They can be long term, such as a special sensitivity to hearing ones own name in a crowded room, or short term, as in the ease with which hungry people notice the smell of food.[92] A simple demonstration of the effect involved very brief presentations of non-words such as sael. Subjects who were told to expect words about animals read it as seal, but others who were expecting boat-related words read it as sail.[92]. Sets can be created by motivation and so can result in people interpreting ambiguous figures so that they see what they want to see.[91] For instance, how someone perceives what unfolds during a sports game can be biased if they strongly support one of the teams.[93] In one experiment, ...