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University of Houston
1.
Lentsch, Matthew.
Objective Measurement of Spectacle Wear Time with a Temperature Sensor Data Logger.
Degree: MS, Physiological Optics and Vision Science, 2017, University of Houston
URL: http://hdl.handle.net/10657/4594
► Purpose: Many practitioners and researchers desire to objectively quantify spectacle wear time. The purpose of this study was to evaluate the Smartbutton Data Logger Temperature…
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▼ Purpose: Many practitioners and researchers desire to objectively quantify spectacle wear time. The purpose of this study was to evaluate the Smartbutton Data Logger Temperature Recorder for monitoring spectacle wear. Methods: Fifty adults (32 female, 18 male) wore a thermosensor on their spectacles for 2 weeks for each of 2 mount types while keeping wear diaries. Temperatures during reported spectacle wear (ON) were compared to temperatures during non-wear (OFF). The success of two methods to approximate wear time was evaluated by percent error with respect to subject reported wear time. The first filtered temperatures, defining wear time from temperature ranges determined from group or individual mean temperatures calculated during subject-reported ON times. The second utilized examiners interpreting temperature versus time plots to identify spectacle wear. Results: Group mean ON (31.8 ± 0.6 ⁰C) and OFF (24.7 ± 1.5 ⁰C) temperatures differed significantly (p<0.001), female ON temperatures averaged 1⁰C higher than males (p=0.04), and there was no significant difference in temperature between mounts (p=0.18) by repeated measures ANOVA. Median percent error and first and third quartiles (Q1, Q3) of each approximation technique was: group mean filtering = 8% (Q1 3%, Q3 18%), individual mean filtering = 7% (Q1 4%, Q3 19%), examiner 1 = 6% (Q1 2%, Q3 14%), examiner 2 = 7% (Q1 3%, Q3 12%). Evaluation of the most detailed diaries (8 subjects) revealed that brief wear intervals and leaving spectacles in a warm, parked car resulted in higher percent error in approximating wear time. Conclusions: The SmartButton is a promising device to monitor spectacle compliance in patients with all approximation methods evaluated providing less than 10% median percent error in wear time.
Advisors/Committee Members: Anderson, Heather A. (advisor), Marsack, Jason D. (committee member), Das, Vallabh E. (committee member).
Subjects/Keywords: Spectacle Compliance; Dose Monitoring; Amblyopia
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APA (6th Edition):
Lentsch, M. (2017). Objective Measurement of Spectacle Wear Time with a Temperature Sensor Data Logger. (Masters Thesis). University of Houston. Retrieved from http://hdl.handle.net/10657/4594
Chicago Manual of Style (16th Edition):
Lentsch, Matthew. “Objective Measurement of Spectacle Wear Time with a Temperature Sensor Data Logger.” 2017. Masters Thesis, University of Houston. Accessed January 20, 2021.
http://hdl.handle.net/10657/4594.
MLA Handbook (7th Edition):
Lentsch, Matthew. “Objective Measurement of Spectacle Wear Time with a Temperature Sensor Data Logger.” 2017. Web. 20 Jan 2021.
Vancouver:
Lentsch M. Objective Measurement of Spectacle Wear Time with a Temperature Sensor Data Logger. [Internet] [Masters thesis]. University of Houston; 2017. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10657/4594.
Council of Science Editors:
Lentsch M. Objective Measurement of Spectacle Wear Time with a Temperature Sensor Data Logger. [Masters Thesis]. University of Houston; 2017. Available from: http://hdl.handle.net/10657/4594

University of Houston
2.
Liu, Su.
Investigation of High Frequency Oscillations in Epilepsy Using Computational Intelligence.
Degree: PhD, Biomedical Engineering, 2017, University of Houston
URL: http://hdl.handle.net/10657/4777
► Epilepsy is effecting over 1% of the population worldwide, wherein 1/3 of the patients remain refractory to medication. Successful surgical treatment for patients with intractable…
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▼ Epilepsy is effecting over 1% of the population worldwide, wherein 1/3 of the patients remain refractory to medication. Successful surgical treatment for patients with intractable epilepsy depends critically on the accurate delineation of the seizure onset zone (SOZ). High frequency oscillations (HFOs, 80 - 500 Hz) are proposed as putative biomarkers in epilepsy with their potentials of identifying the SOZ, either by augmenting or replacing the current preoperative evaluation modality which requires detained visual examination of long-term intracranial EEG recordings. The clinical utility of HFOs has been hampered due to the challenges associated with the quantitative identification of HFOs in massive-volume iEEG datasets. The lack of established criteria for distinguishing pathological HFOs from physiological oscillations also adds to the complexity of the problem.
This dissertation aims at the computational analysis of HFOs with specific concerns over its practical application for the localization and prediction of SOZ. We proposed novel algorithms and tools for the auto-detection of HFO in prolonged clinical data based on advanced signal processing and unsupervised machine learning techniques, and investigated the correlation of possible HFO clusters and clinician-determined SOZ in different states. The algorithm achieved significant improvement compared to existing SOZ approximation techniques, indicating that unsupervised clustering methods exploring the time-frequency content of HFOs in the available full-band can efficiently be used to localize the epileptogenic zone in clinical practice. We further investigated the spatial and temporal dynamics of HFO in long-term iEEG recordings, verified the spatial correlation of HFO and SOZ, and assessed the feasibility using automatically detected HFOs to identify SOZ in challenging cases where the ictal pattern was unclear. Finally, for the first time we introduced SOZ-specific HFO waveform patterns which are barely observed in the functional cortex introducing physiological HFOs.
The outcomes of this work add to our understanding of the electrophysiological basis of HFOs as well as the epileptogenic networks, and provide new possibilities for the interpretation of HFOs that can be efficiently applied to distinguish SOZ from eloquent cortical areas, which is a critical step towards the translation of HFOs to valid clinical biomarkers.
Advisors/Committee Members: Ince, Nuri F. (advisor), Zhang, Yingchun (committee member), Omurtag, Ahmet (committee member), Das, Vallabh E. (committee member), Quach, Michael M. (committee member).
Subjects/Keywords: High frequency oscillation; Epilepsy; Seizure onset zone; IEEG; Unsupervised clustering; Time-frequency analysis
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
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APA (6th Edition):
Liu, S. (2017). Investigation of High Frequency Oscillations in Epilepsy Using Computational Intelligence. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/4777
Chicago Manual of Style (16th Edition):
Liu, Su. “Investigation of High Frequency Oscillations in Epilepsy Using Computational Intelligence.” 2017. Doctoral Dissertation, University of Houston. Accessed January 20, 2021.
http://hdl.handle.net/10657/4777.
MLA Handbook (7th Edition):
Liu, Su. “Investigation of High Frequency Oscillations in Epilepsy Using Computational Intelligence.” 2017. Web. 20 Jan 2021.
Vancouver:
Liu S. Investigation of High Frequency Oscillations in Epilepsy Using Computational Intelligence. [Internet] [Doctoral dissertation]. University of Houston; 2017. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10657/4777.
Council of Science Editors:
Liu S. Investigation of High Frequency Oscillations in Epilepsy Using Computational Intelligence. [Doctoral Dissertation]. University of Houston; 2017. Available from: http://hdl.handle.net/10657/4777

University of Houston
3.
Upadhyaya, Suraj.
Investigating the Role of the Superior Colliculus in Strabismus.
Degree: PhD, Physiological Optics and Vision Science, 2018, University of Houston
URL: http://hdl.handle.net/10657/5701
► Purpose: Strabismus is a global problem with prevalence of 3-5% in infants around the world. Besides eye misalignment, which leads to difficulty in perception of…
(more)
▼ Purpose: Strabismus is a global problem with prevalence of 3-5% in infants around the world. Besides eye misalignment, which leads to difficulty in perception of depth, other associated problems include fixation instability, unequal saccades in two eyes and nystagmus. Traditionally, extraocular muscles were thought to be responsible for ocular misalignment. However, recent data suggests that disrupted vergence circuits in the brain contributes towards strabismus. Before improving treatment modalities, a better understanding of basic neural mechanism and structures involved in strabismus is necessary. Superior Colliculus (SC) is an important visual-oculomotor structure that has been implicated in control of vergence in cats, monkeys, and humans. The goal of this dissertation was to understand the role of the SC in strabismus.
Methods: Prism-reared adult strabismic monkeys (n=6) were used. Scleral search coils were used to measure eye movements. Behavioral-study: Fixational data from five strabismic and one normal monkeys were collected to determine the relationship between fixational saccade amplitude and fixational stability. Electrical stimulation-study: Electrical stimulation (10-40µamp, 400Hz, 500msec) was applied to the SC of three strabismic monkeys to investigate the effect of SC activation on strabismus angle. Neurophysiology-study: Single-cell recording within the rostral SC of two strabismic monkeys was used to localize cells related to eye misalignment. Firing properties of these cells were also studied during 5° and 15° ipsilateral and contralateral saccades and during brief periods of target extinction (300-400ms). Muscimol inactivation-study: Muscimol, a GABA-a agonist inhibitory neurotransmitter, was used to pharmacologically inactivate the SC in two strabismic monkeys to determine a causal role between SC activity and eye misalignment as well as fixation instability of strabismic animals.
Results: Behavioral-study: Amplitude of fixational saccades was larger in strabismic monkeys than that of normal monkeys (p<0.001; one-way-ANOVA). There was a nonlinear relationship between amplitude of fixational saccades and fixation instability such that fixational saccade amplitude saturates for larger fixation instability. Vergence BCEA (instability in depth) was poor in strabismic monkeys. Electrical stimulation-study: Electrical stimulation of SC produced significant changes in the horizontal misalignment that could be either convergent or divergent. Amplitude of electrically-evoked saccades was similar in the two eyes (p>0.05; paired t-test), but directions were different. Approximately 50% of the change in strabismic angle was due to saccade disconjugacy and the other 50% was due to disconjugate post-saccadic drift. Neurophysiological-study: Cells related to eye misalignment were found within the rSC. Some cells showed increased responses for small angles of exotropia (Convergence or near-response cells - NRC) while others showed increased response for larger angles of exotropia (Divergence or far-response…
Advisors/Committee Members: Das, Vallabh E. (advisor), Chino, Yuzo M. (committee member), Harwerth, Ronald S. (committee member), Walton, Mark M. G. (committee member).
Subjects/Keywords: Strabismus; Superior colliculus; Fixational saccades; Non-human primates
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Upadhyaya, S. (2018). Investigating the Role of the Superior Colliculus in Strabismus. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/5701
Chicago Manual of Style (16th Edition):
Upadhyaya, Suraj. “Investigating the Role of the Superior Colliculus in Strabismus.” 2018. Doctoral Dissertation, University of Houston. Accessed January 20, 2021.
http://hdl.handle.net/10657/5701.
MLA Handbook (7th Edition):
Upadhyaya, Suraj. “Investigating the Role of the Superior Colliculus in Strabismus.” 2018. Web. 20 Jan 2021.
Vancouver:
Upadhyaya S. Investigating the Role of the Superior Colliculus in Strabismus. [Internet] [Doctoral dissertation]. University of Houston; 2018. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10657/5701.
Council of Science Editors:
Upadhyaya S. Investigating the Role of the Superior Colliculus in Strabismus. [Doctoral Dissertation]. University of Houston; 2018. Available from: http://hdl.handle.net/10657/5701

University of Houston
4.
-1421-5910.
Investigation of Spatio-Spectral Dynamics of Local Field Potentials in Parkinson’s Disease.
Degree: PhD, Biomedical Engineering, 2017, University of Houston
URL: http://hdl.handle.net/10657/4776
► Parkinson’s disease (PD) is characterized by the progressive loss of dopaminergic nigral neurons resulting in motor and non-motor deficits. Deep brain stimulation (DBS) of the…
(more)
▼ Parkinson’s disease (PD) is characterized by the progressive loss of dopaminergic nigral neurons resulting in motor and non-motor deficits. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has emerged as an effective neurosurgical treatment for the patients with PD where their motor symptoms cannot be controlled with medications. Accurate localization of STN is an important factor defining the efficacy of DBS. The most common targeting method in DBS surgery is the microelectrode single unit activity recording, which is performed by listening to bursting firing patterns of individual neurons to identify the basal ganglia structures. However, it requires significant expertise and is fraught by potential technical difficulties. On the other hand, local field potentials (LFPs), owing to their oscillatory and robust nature, can overcome these technical issues. In this regard, we recorded LFPs from multitrack microelectrodes and macroelectrode in PD patients who underwent DBS surgery. We demonstrated for the first time that combination of different subband features derived from beta and high frequency oscillations of LFPs can be used to estimate the optimal track for DBS implantation and to identify the dorsal STN border with high accuracy. These results establish the initial evidence that LFPs can be strategically fused with computational intelligence in the operating room to increase the chance of optimal placement of the DBS electrode within the motor sub-territory of the STN, without an appreciable downside.
We also investigated the spatio-spectral patterns of LFPs in the most commonly accepted subtypes of PD, tremor dominant (TD) and postural instability and gait difficulty (PIGD). As of today, no underlying neural correlates have been identified. Here we show that activity in the subbands of LFPs recorded with microelectrodes from sub-territories of the STN provide distinguishing neurophysiological information about these phenotypes. We found distinct patterns between TD and PIGD groups in HFOs and their interaction with the beta band in the dorsal and ventral regions of the STN. Our results indicate that the spatio-spectral dynamics of LFPs can be used as an objective method to distinguish the two major subtypes of PD. This observation provides support for distinct pathophysiologic mechanisms underlying these subtypes.
Advisors/Committee Members: Ince, Nuri F. (advisor), Omurtag, Ahmet (committee member), Zhang, Yingchun (committee member), Das, Vallabh E. (committee member), Viswanathan, Ashwin (committee member), Jimenez-Shahed, Joohi (committee member).
Subjects/Keywords: Parkinson's Disease; Local field potentials; Subthalamic nucleus; Intraoperative recordings
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
-1421-5910. (2017). Investigation of Spatio-Spectral Dynamics of Local Field Potentials in Parkinson’s Disease. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/4776
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-1421-5910. “Investigation of Spatio-Spectral Dynamics of Local Field Potentials in Parkinson’s Disease.” 2017. Doctoral Dissertation, University of Houston. Accessed January 20, 2021.
http://hdl.handle.net/10657/4776.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-1421-5910. “Investigation of Spatio-Spectral Dynamics of Local Field Potentials in Parkinson’s Disease.” 2017. Web. 20 Jan 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-1421-5910. Investigation of Spatio-Spectral Dynamics of Local Field Potentials in Parkinson’s Disease. [Internet] [Doctoral dissertation]. University of Houston; 2017. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10657/4776.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-1421-5910. Investigation of Spatio-Spectral Dynamics of Local Field Potentials in Parkinson’s Disease. [Doctoral Dissertation]. University of Houston; 2017. Available from: http://hdl.handle.net/10657/4776
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Houston
5.
Agaoglu, Mehmet Naci.
Nonretinotopic Reference Frames for Dynamic Form and Motion Perception.
Degree: PhD, Electrical Engineering, 2015, University of Houston
URL: http://hdl.handle.net/10657/1922
► The spatial representation of a visual scene in the early visual system is well known. The optics of the eye map the three-dimensional environment onto…
(more)
▼ The spatial representation of a visual scene in the early visual system is well known. The optics of the eye map the three-dimensional environment onto two-dimensional images on the retina. These retinotopic representations are preserved in the early visual system. Retinotopic representations and processing are among the most prevalent concepts in visual neuroscience. However, it has long been known that a retinotopic representation of the stimulus is neither sufficient nor necessary for perception. Many visual processes (form and motion perception, visual search, attention, and perceptual learning) that have been thought to occur in retinotopic coordinates, have been found to operate in non-retinotopic coordinates. Based on these findings, our goal was to characterize the non-retinotopic representations and their underlying reference frames. We proposed that each retinotopic motion vector creates a perceptual reference-frame field in the retinotopic space (like an electromagnetic field), and interactions between these fields determine the selection of the effective reference frame. To test this theory, we performed a series of psychophysical experiments. We first used the slit-viewing paradigm to investigate how features of a moving object are attributed. Our results support the predictions of the non-retinotopic feature-processing hypothesis and demonstrate the ability of the visual system to operate non-retinotopically at a fine feature processing level. We then used a variant of the induced motion paradigm to investigate non-retinotopic reference frames for motion perception. We found that the effective reference frame for motion perception is non-retinotopic, and emerges from an amalgamation of motion-based, retinotopic and spatiotopic reference frames. In determining the percept, the influence of relative motion, defined by a motion-based reference frame, dominates those of retinotopic and spatiotopic motions within a finite region. Moreover, we found that different reference fields interact nonlinearly, and the way they interact depends on how motion vectors are grouped. Finally, we investigated how various spatiotemporal factors influence reference frame selection for motion perception. In line with our theory, we found that the motion-based-nearest-vector metric can fully account for all the data reported here. Taken together, these findings suggest that the brain actively constructs perceptual space by using motion-based reference frames.
Advisors/Committee Members: Ogmen, Haluk (advisor), Sheth, Bhavin R. (committee member), Das, Vallabh E. (committee member), Contreras-Vidal, Jose L. (committee member), Herzog, Michael H. (committee member).
Subjects/Keywords: Reference frames; Motion perception; Retinotopy; Induced motion; Feature attribution
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Agaoglu, M. N. (2015). Nonretinotopic Reference Frames for Dynamic Form and Motion Perception. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/1922
Chicago Manual of Style (16th Edition):
Agaoglu, Mehmet Naci. “Nonretinotopic Reference Frames for Dynamic Form and Motion Perception.” 2015. Doctoral Dissertation, University of Houston. Accessed January 20, 2021.
http://hdl.handle.net/10657/1922.
MLA Handbook (7th Edition):
Agaoglu, Mehmet Naci. “Nonretinotopic Reference Frames for Dynamic Form and Motion Perception.” 2015. Web. 20 Jan 2021.
Vancouver:
Agaoglu MN. Nonretinotopic Reference Frames for Dynamic Form and Motion Perception. [Internet] [Doctoral dissertation]. University of Houston; 2015. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10657/1922.
Council of Science Editors:
Agaoglu MN. Nonretinotopic Reference Frames for Dynamic Form and Motion Perception. [Doctoral Dissertation]. University of Houston; 2015. Available from: http://hdl.handle.net/10657/1922

University of Houston
6.
Gonen, Fahrettin Firat 1986-.
Real-Time Visual Stimulus Selection through Attentional and Decisional Processes.
Degree: PhD, Electrical Engineering, 2017, University of Houston
URL: http://hdl.handle.net/10657/4608
► Our senses continuously receive a staggering amount of information from our environment. To operate efficiently in a natural environment, our brain needs to select in…
(more)
▼ Our senses continuously receive a staggering amount of information from our environment. To operate efficiently in a natural environment, our brain needs to select in real-time a subset of the information impinging on our senses. Two processes play a crucial role in real-time stimulus selection and filtering: attentional and decisional processes. The broad goal of our study was to investigate how attentional and decisional processes select visual inputs for processing. The study was divided into three parts: The first and second parts studied visual attention. The last part examined decisional processes. In the first part, we investigated the allocation of exogenous attention when perceptual groups were formed or dissolved. By varying the relative timing between the cue onset and the formation, or dissolution of perceptual groups, we sought to understand the relationship between processes organizing inputs into meaningful units (perceptual grouping) and the processes selecting from these units (attention). The time-course of attentional benefits of grouping was remarkably similar in the case of group formation and dissolution, operating within a half-second time frame. The results revealed the dynamics of how attention and grouping work in synergy during the transient period when groups form or dissolve.
Attentional processes can be divided into two types: a fast reflexive process, called exogenous attention, and a slower, voluntary process, called endogenous attention. In the second part, we investigated whether endogenous and exogenous attention, operate independently or interact. The experiment demonstrated that there is an interaction between the endogenous and exogenous systems when the task was discrimination. The evidence for interaction was weak when subject’s task was detection. The interaction between the two orientation types depends on the validity of both types of orientations. When endogenous cue was valid, exogenous cue’s strength was weakened. The endogenous cue was significantly dominant than the exogenous cue. The detection tasks required significantly less time compared to discrimination tasks.
In the last part, we examined information sampling by decisional processes. We tested the Small Sample Advantage (SSA) theory through predictions and found that for the low environmental contingency values, subjects preferred small sample sizes. For the remaining values, the prediction results were not conclusive. Under SSA, probability density function analysis indicates that the percentage correct can never exceed 50%. However, we carried out simulations to test whether the specific realization corresponding to our experiment could yield performance higher than 50% under SSA. Simulation results showed that indeed this was the case and produced an estimate of internal decision level used by the subjects.
Advisors/Committee Members: Ogmen, Haluk (advisor), Breitmeyer, Bruno G. (committee member), Sheth, Bhavin R. (committee member), Contreras-Vidal, Jose L. (committee member), Das, Vallabh E. (committee member).
Subjects/Keywords: Attention; Perceptual grouping; Small sample advantage; Exogenous; Endogenous; Object-based attention; Space-based attention
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Gonen, F. F. 1. (2017). Real-Time Visual Stimulus Selection through Attentional and Decisional Processes. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/4608
Chicago Manual of Style (16th Edition):
Gonen, Fahrettin Firat 1986-. “Real-Time Visual Stimulus Selection through Attentional and Decisional Processes.” 2017. Doctoral Dissertation, University of Houston. Accessed January 20, 2021.
http://hdl.handle.net/10657/4608.
MLA Handbook (7th Edition):
Gonen, Fahrettin Firat 1986-. “Real-Time Visual Stimulus Selection through Attentional and Decisional Processes.” 2017. Web. 20 Jan 2021.
Vancouver:
Gonen FF1. Real-Time Visual Stimulus Selection through Attentional and Decisional Processes. [Internet] [Doctoral dissertation]. University of Houston; 2017. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10657/4608.
Council of Science Editors:
Gonen FF1. Real-Time Visual Stimulus Selection through Attentional and Decisional Processes. [Doctoral Dissertation]. University of Houston; 2017. Available from: http://hdl.handle.net/10657/4608

University of Houston
7.
Sridhar, Deepika.
Relative Contributions of Eye-Position and Retinal Information to Perceived Egocentric Visual Direction.
Degree: PhD, Physiological Optics and Vision Science, 2011, University of Houston
URL: http://hdl.handle.net/10657/502
► Purpose: Visual directions of object(s) in space are judged with reference either to the self (egocentric), or to the eye (oculocentric). Perceived egocentric direction (EVD)…
(more)
▼ Purpose: Visual directions of object(s) in space are judged with reference either to the self (egocentric), or to the eye (oculocentric). Perceived egocentric direction (EVD) is based on the combination of sensed eye-position in the orbits, provided by proprioception and efference copies, and retinal information provided by local sign mechanisms. This dissertation examined whether (1) the eye-position and the retinal information covary within the same subjects, (2) the eye-position information from the non-viewing eye contributes to perceived EVD during complete absence of retinal information from one eye, (3) the contribution of eye-position information varies similarly in the presence and absence of foveal suppression, (4) vergence eye movements contribute to perceived EVD, and (5) differences in eye velocities can account for differences in perceived EVD for different viewing conditions.
Methods: The relative contributions of eye-position information from the two eyes during different viewing conditions were determined by open-loop pointing responses to an isolated target presented at one of several horizontal locations on a completely black background. These targets were presented binocularly with either asymmetric or symmetric vergence demands, and monocularly during heterophoria. The targets were either static, or were ramped with a constant asymmetric vergence velocity of 0.75 or 1.5 deg/s. The effect of foveal suppression on the eye-position information was determined using targets with 1.5D of anisometropic blur. The relative contributions of retinal information from each eye were estimated by an alignment task, for contrast-varying targets with horizontal or vertical disparity, and for luminance-varying targets with horizontal disparity. Comparisons of relative contributions of eye-position information during asymmetric vergence and retinal information for targets of unequal contrast or luminance in the two eyes indicated if the two sources of information covary within the same subjects. Comparisons of the contributions of eye-position information during binocular viewing and asymmetric vergence with monocular viewing, suppression of foveal information, and different eye-velocities indicated whether the contribution of eye-position to perceived EVD remains similar during different viewing conditions.
Results: Between-eye differences exist in the contributions of eye-position and retinal information in some subjects. Across subjects, the inferred weighting of eye-position and retinal information covaries quantitatively (p < 0.05). During monocular viewing, the contribution of eye-position information from the non-viewing eye varies idiosyncratically. The contribution of eye-position information from a foveally suppressed eye is less than when no suppression occurs. In subjects who weight the position information from the two eyes unequally, changes in perceived direction were noted during symmetric vergence. No statistically significant differences in the contributions of eye-position information occur…
Advisors/Committee Members: Bedell, Harold E. (advisor), Das, Vallabh E. (committee member), Manny, Ruth E. (committee member), Stevenson, Scott B. (committee member), Patel, Saumil S. (committee member).
Subjects/Keywords: Perception; Oculocentric direction; Vergence; Eye-position; Visual direction; Hering's law; Eye – Movements; Physiological optics; Binocular rivalry
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Sridhar, D. (2011). Relative Contributions of Eye-Position and Retinal Information to Perceived Egocentric Visual Direction. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/502
Chicago Manual of Style (16th Edition):
Sridhar, Deepika. “Relative Contributions of Eye-Position and Retinal Information to Perceived Egocentric Visual Direction.” 2011. Doctoral Dissertation, University of Houston. Accessed January 20, 2021.
http://hdl.handle.net/10657/502.
MLA Handbook (7th Edition):
Sridhar, Deepika. “Relative Contributions of Eye-Position and Retinal Information to Perceived Egocentric Visual Direction.” 2011. Web. 20 Jan 2021.
Vancouver:
Sridhar D. Relative Contributions of Eye-Position and Retinal Information to Perceived Egocentric Visual Direction. [Internet] [Doctoral dissertation]. University of Houston; 2011. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10657/502.
Council of Science Editors:
Sridhar D. Relative Contributions of Eye-Position and Retinal Information to Perceived Egocentric Visual Direction. [Doctoral Dissertation]. University of Houston; 2011. Available from: http://hdl.handle.net/10657/502

University of Houston
8.
Pirdankar, Onkar Harishchandra.
Fixation Stability in Monkeys with Strabismus.
Degree: MS, Physiological Optics and Vision Science, University of Houston
URL: http://hdl.handle.net/10657/4101
► Purpose: To assess the effect of target parameters on fixation stability in strabismic monkeys. Methods: Eye movements were recorded in one normal and three strabismic…
(more)
▼ Purpose: To assess the effect of target parameters on fixation stability in strabismic monkeys.
Methods: Eye movements were recorded in one normal and three strabismic monkeys during 72 fixation conditions (4 shapes; 3 sizes; 2 backgrounds; OD, OS or OU viewing), each repeated 5 times. Fixation stability was quantified using the Bivariate Contour Ellipse Area (BCEA). Influence of target parameters was assessed using 4-way ANOVA.
Results: BCEA was greater in the strabismic monkeys compared to the normal. In strabismus, BCEA of the deviated eye was significantly greater than BCEA in the fixating eye. Target shape and size significantly influenced fixation stability in both normal and strabismic monkeys. Background effects were idiosyncratic.
Conclusions: Target parameters that influence fixation stability in a normal, also affects fixation stability in disease conditions such as strabismus. Target parameter influences likely function via conjugate mechanisms since proportional effects were observed in both viewing and covered eyes.
Advisors/Committee Members: Das, Vallabh E. (advisor), Chino, Yuzo M. (committee member), Bedell, Harold E. (committee member).
Subjects/Keywords: Strabismus; Eye movements; Fixation stability
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APA (6th Edition):
Pirdankar, O. H. (n.d.). Fixation Stability in Monkeys with Strabismus. (Masters Thesis). University of Houston. Retrieved from http://hdl.handle.net/10657/4101
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Chicago Manual of Style (16th Edition):
Pirdankar, Onkar Harishchandra. “Fixation Stability in Monkeys with Strabismus.” Masters Thesis, University of Houston. Accessed January 20, 2021.
http://hdl.handle.net/10657/4101.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
MLA Handbook (7th Edition):
Pirdankar, Onkar Harishchandra. “Fixation Stability in Monkeys with Strabismus.” Web. 20 Jan 2021.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Vancouver:
Pirdankar OH. Fixation Stability in Monkeys with Strabismus. [Internet] [Masters thesis]. University of Houston; [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10657/4101.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Council of Science Editors:
Pirdankar OH. Fixation Stability in Monkeys with Strabismus. [Masters Thesis]. University of Houston; Available from: http://hdl.handle.net/10657/4101
Note: this citation may be lacking information needed for this citation format:
No year of publication.

University of Houston
9.
Neerkaje, Shrivatsa.
Estimating the Emotional Content of an Image from the Observer's Eye Scan Patern.
Degree: MSin Electrical Engineering, Electrical Engineering, University of Houston
URL: http://hdl.handle.net/10657/3678
► The aim of the study is to predict the emotional gist of the image, namely the level of arousal (low or high) and kind of…
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▼ The aim of the study is to predict the emotional gist of the image, namely the level of arousal (low or high) and kind of emotion (positive or negative) that the image elicits from the pattern of eye movements of a human observer. Images were selected based on their arousal and valence ratings. The observers (n=32) viewed the images in a random order and their pattern of eye movements was recorded with a head-mounted eye tracker. Features pertaining to saccades and fixation were extracted. Feature values obtained from the eye scan pattern data were fed into a random forest algorithm in MATLAB. Performing 10 fold cross-validation yielded a classification efficiency of 57% on low versus high arousal images, and 56% on positive versus negative valence images (a priori probability=50%). Several dynamic features were added to improve the efficiency though the effort proved to be unfruitful. Finally, the images were checked to see if they really show any difference by training them through a Convolutional Neural Network. The model showed a classification efficiency of 85% based on Valence and 75% based on Arousal.
Advisors/Committee Members: Sheth, Bhavin R. (committee member), Vilalta, Ricardo (committee member), Das, Vallabh E. (committee member), Jackson, David R. (committee member).
Subjects/Keywords: Emotion Classification; Predictive analytics
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Record Details
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Neerkaje, S. (n.d.). Estimating the Emotional Content of an Image from the Observer's Eye Scan Patern. (Masters Thesis). University of Houston. Retrieved from http://hdl.handle.net/10657/3678
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Chicago Manual of Style (16th Edition):
Neerkaje, Shrivatsa. “Estimating the Emotional Content of an Image from the Observer's Eye Scan Patern.” Masters Thesis, University of Houston. Accessed January 20, 2021.
http://hdl.handle.net/10657/3678.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
MLA Handbook (7th Edition):
Neerkaje, Shrivatsa. “Estimating the Emotional Content of an Image from the Observer's Eye Scan Patern.” Web. 20 Jan 2021.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Vancouver:
Neerkaje S. Estimating the Emotional Content of an Image from the Observer's Eye Scan Patern. [Internet] [Masters thesis]. University of Houston; [cited 2021 Jan 20].
Available from: http://hdl.handle.net/10657/3678.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Council of Science Editors:
Neerkaje S. Estimating the Emotional Content of an Image from the Observer's Eye Scan Patern. [Masters Thesis]. University of Houston; Available from: http://hdl.handle.net/10657/3678
Note: this citation may be lacking information needed for this citation format:
No year of publication.
.