Temporal Integration of Alternately Exposed Monocular Images of a Random-Dot Stereogram

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 312-312
Author(s):  
W Pieper
Keyword(s):  
Temporal Integration ◽  
Female Students ◽  
Stereoscopic Vision ◽  
Binocular Fusion ◽  
Cortical Cells ◽  
Fixation Mark ◽  
Interpupillary Distance ◽  
Frequency Threshold ◽  
Random Dot Stereogram ◽  
The Right

J R Ewald and O Gross (1906 Pflügers ArchivCXV 514 – 521) reported that monocular half-images presented alternately can be fused to a stereoscopic percept. The situation is like looking through a fence close to the eyes, with picket and gap widths being identical to the interpupillary distance. Though vision is monocular, an observer moving fast enough parallel to the fence will have stereoscopic vision of the scenery behind it. Little is known about the limits of this integrating mechanism. In two experiments, LCD shutter glasses were used to control the viewing conditions of the anaglyphs of a random-dot stereogram. Binocular fusion was supported by a visible binocular fixation mark and a frame around the display. Subjects were eight male and three female students with normal stereoscopic acuity. They were instructed to press a key as long as they could perceive a global figure portrayed in the stereogram (25 min arc disparity). In experiment 1, monocular exposures to the right and the left eye followed each other without pauses. Psychophysical procedures were used to determine the frequency threshold for stereopsis. A breakdown frequency of 2.5 Hz was found, for descending as well as ascending series. Transferred to the concrete example of a fence, the result corresponds to a pace of 0.32 m s−1, with an interocular distance and a fence measure of 63 mm. In experiment 2, alternating monocular exposures of 100 ms duration were separated by variable pauses. Stereopsis disappeared with 8 ms pauses (ascending), and 17 ms pauses (descending). Results may be attributed to integrating mechanisms of binocular cortical cells, rather than to retinal processes (afterimages).

Burst Firing and Modulation of Functional Connectivity in Cat Striate Cortex

1998 ◽  
Vol 80 (2) ◽  
pp. 730-744 ◽  
Author(s):  
R. K. Snider ◽  
J. F. Kabara ◽  
B. R. Roig ◽  
A. B. Bonds
Keyword(s):  
Functional Connectivity ◽  
Cross Correlation ◽  
Striate Cortex ◽  
Temporal Integration ◽  
Burst Firing ◽  
Correlation Peak ◽  
Cortical Cells ◽  
Instantaneous Rate ◽  
Cross Correlation Analysis ◽  
Cat Striate Cortex

Snider, R. K., J. F. Kabara, B. R. Roig, and A. B. Bonds. Burst firing and modulation of functional connectivity in cat striate cortex. J. Neurophysiol. 80: 730–744, 1998. We studied the influences of the temporal firing patterns of presynaptic cat visual cortical cells on spike generation by postsynaptic cells. Multiunit recordings were dissected into the activity of individual neurons within the recorded group. Cross-correlation analysis was then used to identify directly coupled neuron pairs. The 22 multiunit groups recorded typically showed activity from two to six neurons, each containing between 1 and 15 neuron pairs. From a total of 241 neuron pairs, 91 (38%) had a shifted cross-correlation peak, which indicated a possible direct connection. Only two multiunit groups contained no shifted peaks. Burst activity, defined by groups of two or more spikes with intervals of ≤8 ms from any single neuron, was analyzed in terms of its effectiveness in eliciting a spike from a second, driven neuron. We defined effectiveness as the percentage of spikes from the driving neuron that are time related to spikes of the driven neuron. The effectiveness of bursts (of any length) in eliciting a time-related response spike averaged 18.53% across all measurements as compared with the effectiveness of single spikes, which averaged 9.53%. Longer bursts were more effective than shorter ones. Effectiveness was reduced with spatially nonoptimal, as opposed to optimal, stimuli. The effectiveness of both bursts and single spikes decreased by the same amount across measurements with nonoptimal orientations, spatial frequencies and contrasts. At similar firing rates and burst lengths, the decrease was more pronounced for nonoptimal orientations than for lower contrasts, suggesting the existence of a mechanism that reduces effectiveness at nonoptimal orientations. These results support the hypothesis that neural information can be emphasized via instantaneous rate coding that is not preserved over long intervals or over trials. This is consistent with the integrate and fire model, where bursts participate in temporal integration.

scholarly journals The EEG Activity during Binocular Depth Perception of 2D Images

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Marsel Fazlyyyakhmatov ◽  
Nataly Zwezdochkina ◽  
Vladimir Antipov
Keyword(s):  
Cognitive Task ◽  
Cortical Activity ◽  
Stereoscopic Vision ◽  
Image Perception ◽  
Brain Functions ◽  
Before And After ◽  
False Image ◽  
Random Dot Stereogram ◽  
The Brain ◽  
Band Activity

The central brain functions underlying a stereoscopic vision were a subject of numerous studies investigating the cortical activity during binocular perception of depth. However, the stereo vision is less explored as a function promoting the cognitive processes of the brain. In this work, we investigated a cortical activity during the cognitive task consisting of binocular viewing of a false image which is observed when the eyes are refocused out of the random-dot stereogram plane (3D phenomenon). The power of cortical activity before and after the onset of the false image perception was assessed using the scull EEG recording. We found that during stereo perception of the false image the power of alpha-band activity decreased in the left parietal area and bilaterally in frontal areas of the cortex, while activity in beta-1, beta-2, and delta frequency bands remained to be unchanged. We assume that this suppression of alpha rhythm is presumably associated with increased attention necessary for refocusing the eyes at the plane of the false image.

scholarly journals The Effect Ofinitial Practice with Dominant and Non-Dominant Hand on Acquisition, Retention and Transfer of a Complex Motor Task

2017 ◽  
Vol 14 (3) ◽  
pp. 1067-1074 ◽  
Author(s):  
Malihe Moones Tousi ◽  
Toktam Emami ◽  
Seyed Mojtaba Hoseini
Keyword(s):  
Movement Time ◽  
Motor Task ◽  
Transfer Task ◽  
Female Students ◽  
Dominant Hand ◽  
Left Hand ◽  
Right Hand ◽  
Significant Difference ◽  
Post Test ◽  
The Right

ABSTRACT: The purpose of this study is to analyze the effect of practice orderwithdominant and non-dominant hand on acquisition, retention and transfer of basketball dribbling skills of female students at Ferdowsi University. The subjects were 20 female students of General Physical Education (19-24), who did not have any experiences in basketball with dominant right hand. They were randomly selected and equally assigned into two groups. The subjects practiced within the program for 4 weeks, 2 times a week and 45 minutes per session. Group A practiced with their dominant right hand for the first four sessions and then switched to their left hand for the second four sessions. Group B practiced reversely. The subjects were assessed by Slalom-Dribble-Test in pre-test and post-test. Retention and transfer tests were performed one week after the exercise was finished. The results showed that there was no significant difference between the two groups in acquisition of dribbling skill (p=0.053). Movement time has been significantly reduced from pre-test to post-test (p=0.00). The results showed better performance of the right hand compared to the left (p=0.042). Both groups had a shorter dribbling time with the right hand compared to the left hand in the post-test and retention test. There was no significant difference between two groups in transfer task (p = 0.16). The results indicate that practicing with dominant and non-dominant limbs in the initial motor learning seems to be important to improve performance of both limbs and to strengthen bilateral competence of the learners.

scholarly journals Cortical inhibitory network selects cerebellar signals for movement initiation

2020 ◽  
Author(s):  
Abdulraheem Nashef ◽  
Oren Cohen ◽  
Steve I. Perlmutter ◽  
Yifat Prut
Keyword(s):  
Motor Cortex ◽  
Ampa Receptors ◽  
Cortical Neurons ◽  
Signal To Noise Ratio ◽  
Large Population ◽  
Pyramidal Cells ◽  
Movement Initiation ◽  
Cortical Cells ◽  
Sequence Of Events ◽  
The Right

SUMMARYThe onset of voluntary movements is driven by coordinated firing across a large population of motor cortical neurons. This pattern of activity is determined by both local interactions and long-range corticocortical and subcortical inputs. The way remote areas of the brain communicate to effectively drive movement is still unclear. We addressed this question by studying an important pathway through which the cerebellum communicates, via the motor thalamus, with the motor cortex. We found that similar to the sensory cortices, thalamic input to the motor cortex triggers feedforward inhibition by directly contacting inhibitory cells via particularly effective GluR2- lacking AMPA receptors blocked by NASPM. Based on these results, we constructed a classifier for SCP-responsive cortical cells to identify pyramidal and PV interneurons and study their role in controlling movements. The findings indicate that PV and pyramidal cells are co-driven by TC input in response to activation of the CTC pathway. During task performance, PV and pyramidal cells had comparable relations to movement parameters (directional tuning and movement duration). However, PV interneurons exhibited stronger movement-related activity that preceded the firing of pyramidal cells. This seemingly counterintuitive sequence of events where inhibitory cells are recruited more strongly and before excitatory cells may in fact enhance the signal-to-noise ratio of cerebellar signals by suppressing other inputs and prioritizing the excitatory synchronized volley from the TC system which occurs at the right time to overcome the inhibitory signal. In this manner, the CTC system can shape cortical activity in a way that exceeds its sheer synaptic efficacy.

scholarly journals Threshold Values of Myopic Anisometropia Causing Loss of Stereopsis

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Maciej Gawęcki
Keyword(s):  
Binocular Vision ◽  
Healthy Subjects ◽  
Stereoscopic Vision ◽  
Spherical Equivalent ◽  
Threshold Values ◽  
Inclusion Criteria ◽  
Different Types ◽  
Significant Impairment ◽  
The Subject ◽  
The Right

Purpose. The aim of the study was to determine the threshold values of myopic anisometropia that lead to the loss of stereoacuity in most of patients. Materials and Methods. Forty healthy subjects were included in the study. The inclusion criteria were as follows: lack of any functional or morphological ophthalmological disorders, or detectable damage to the visual system, anisometropia equal or less than 0.25 D in a spherical equivalent, and full stereoscopic vision for near and for distance. Myopic anisometropia was evoked by placing different focusing lenses in front of the right eye of the subject in the trial frame. Stereoscopic vision was assessed with the use of the Titmus test (dots) (Stereo Fly Test Stereo Optical Co. Inc.) for near and the Randot test for distance (Distance Randot Stereotest Stereo Optical Co. Inc.). Results. The threshold values for different types of myopic anisometropia for the loss of stereopsis in more than 50% of patients were determined. For near, this value was 3 D for sphere and “against the rule astigmatism” and 4 D for “with the rule astigmatism”. For distance, the values were 2 D for sphere and “against the rule astigmatism” and 3 D for “with the rule astigmatism.” Conclusions. Myopic anisometropia of more than 2 D can cause a significant impairment of binocular vision. Stereoacuity at distance is more sensitive to myopic anisometropia than stereoacuity at near. Myopic anisometropia involving “against the rule” astigmatism potentially affects binocularity more than anisometropia with regular astigmatism. A prompt correction of anisometropia of more than 2 D is needed in children to prevent the development of amblyopia.

Methodological approaches to improving hip joint mobility among female students of higher educational institutions

2021 ◽  
pp. 75-81
Author(s):  
Yana V. Platonova ◽  
Valentina I. Syutina
Keyword(s):  
Hip Joint ◽  
Maximum Amplitude ◽  
Female Students ◽  
Joint Mobility ◽  
Hip Joints ◽  
Limited Mobility ◽  
Mobility Problem ◽  
Hip Diseases ◽  
The Right ◽  
Hip Flexion

Introduction. The statistics revealed during the literature analysis indicates the wide-spread of joint diseases worldwide, including hip diseases, and all human motor activity depends on the hip functioning. Limited mobility in the joint is caused by a sedentary lifestyle and the absence of movements with involved hip joint. The practice of conducting recreational aerobics classes with female students has shown the lack of girls’ proper attention to the mobility problem in the hip joints. Methods. 200 female students of 1–4 courses of Derzhavin Tambov State University, engaged in recreational aerobics, took part in the study of hip joint mobility. The study used tests to assess the degree of hip joint opening and to identify the presence of asymmetry when the legs are pulled to the sides. Results. There is a unidirectional tendency in the ability to perform motor action with the maximum amplitude of movement in the hip joints of female students of 1–4 courses. The thighs of the students open in the same way; there is no asymmetry between the right and left legs when opening. Conclusions. The study helped to draw up an overall balance and identify trends in the development of hip joint mobility in girls, to understand the causes leading to pelvic displacement and limited hip flexion amplitude, to expand the understanding of methods for assessing hip joint mobility and tests for detecting asymmetry when the legs are pulled to the sides.

Representation of Stereoscopic Depth Based on Relative Disparity in Macaque Area V4

2007 ◽  
Vol 98 (1) ◽  
pp. 241-252 ◽  
Author(s):  
Kazumasa Umeda ◽  
Seiji Tanabe ◽  
Ichiro Fujita
Keyword(s):  
Stereoscopic Vision ◽  
Stereoscopic Depth ◽  
Common Mechanism ◽  
Tuning Curves ◽  
Area V4 ◽  
Neural Representations ◽  
Area V2 ◽  
Random Dot Stereogram ◽  
V4 Neurons ◽  
Background Feature

Stereoscopic vision is characterized by greater visual acuity when a background feature serves as a reference. When a reference is present, the perceived depth of an object is predominantly dependent on this reference. Neural representations of stereoscopic depth are expected to have a relative frame of reference. The conversion of absolute disparity encoded in area V1 to relative disparity begins in area V2, although the information encoded in this area appears to be insufficient for stereopsis. This study examines whether relative disparity is encoded in a higher cortical area. We recorded the responses of V4 neurons from macaque monkeys to various combinations of the absolute disparities of two features: the center patch and surrounding annulus of a dynamic random-dot stereogram. We analyzed the effects of the disparity of the surrounding annulus on the tuning for the disparity of the center patch; the tuning curves of relative-disparity–selective neurons for disparities of the center patch should shift with changes in the disparity of the surrounding annulus. Most V4 tuning curves exhibited significant shifts. The magnitudes of the shifts were larger than those reported for V2 neurons and smaller than that expected for an ideal relative-disparity–selective cell. No correlation was found between the shift magnitude and the degree of size suppression, suggesting that the two phenomena are not the result of a common mechanism. Our results suggest that the coding of relative disparity advances as information flows along the cortical pathway that includes areas V2 and V4.

False Consensus Bias and Gender: Presidential Preferences and the Right to Choose

1994 ◽  
Vol 75 (3_suppl) ◽  
pp. 1601-1602 ◽  
Author(s):  
Clifford E. Brown ◽  
Vicki L. Shuman
Keyword(s):  
Female Students ◽  
False Consensus ◽  
And Gender ◽  
The Right ◽  
Consensus Bias ◽  
Pro Life ◽  
Pro Choice

Both Clinton supporters and pro-choice advocates (31 male and 79 female students of psychology) underestimated the prevalence of their own opinions; yet their estimates were higher than those made by individuals with differing opinions. Although both women and men strongly and similarly favored pro-choice over pro-life, women presumed that men would be less likely to favor the pro-choice position.

Investigation of Temporal Integration by Video Sampling

Perception ◽  
1973 ◽  
Vol 2 (4) ◽  
pp. 441-490 ◽  
Author(s):  
R Williams
Keyword(s):  
Information Integration ◽  
Temporal Integration ◽  
Recognition Task ◽  
Theoretical Models ◽  
Stereoscopic Depth ◽  
Critical Duration ◽  
Integration Time ◽  
Binocular Fusion ◽  
Central Process ◽  
Time Critical

The results from the preliminary set of experiments in which a new video sampling apparatus was used are reported. With the aid of this apparatus experiments were carried out to measure the maximum visual temporal integration time (critical duration) at various background intensities (0·034–34 cd m−2). The aim was to determine to what extent this phenomenon is attributable to either ‘central’ or ‘peripheral’ events. The extended integration period found for the number recognition task is interpreted as evidence of a ‘central’ process; to follow the argument further, an attempt was made to demonstrate information integration using a rotating form in a similar identification–discrimination situation. Monocular, binocular, and dichoptic arrangements were employed, and the amount of dichoptic summation of form information, achieved by both normal and strabismic subjects without stereoscopic depth perception, was used to test two theoretical models of binocular fusion. In addition, stereoscopic depth was generated with uncorrected sampling of the left and right images, which may be due to the action of a ‘fusion hierarchy’. Signal detection theory is suggested as a possible solution to the problem of expectation effects in identification-threshold experiments.

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