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Beyoglu Eye Journal 2024It was aimed to to provide a comprehensive assessment of therapeutic and tectonic emergency keratoplasty procedures, along with a discussion on their indications,...
OBJECTIVES
It was aimed to to provide a comprehensive assessment of therapeutic and tectonic emergency keratoplasty procedures, along with a discussion on their indications, prognostic factors for functional success, and postoperative outcomes.
METHODS
Patients who underwent therapeutic or tectonic Penetrating Keratoplasty (PKP) procedures between 2010 to 2021 in our hospital were retrospectively reviewed. Patient files were evaluated in terms of demographic characteristics, medical and ocular history, visual acuity, initial ocular findings, presence of glaucoma, causative microorganisms, details of surgical procedures, complications, graft transparency and globe integrity. Visual acuity was measured as light perception, hand motion, counting finger, Snellen chart and subsequently converted to Logarithm of the Minimum Angle of Resolution (logMAR) for statistical analysis.
RESULTS
The study included a total of 43 patients, with 16 (37.2%) being female. The average age of the participants was 59.72±18.1 years. The corrected distance visual acuity improved from 2.3±0.66 logMAR preoperatively to 1.72±1.02 logMAR postoperatively (p=0.001). After PKP, anatomical success was achieved in all eyes and functional success was achieved in 23 (51.1%) eyes. It was observed that only preoperative glaucoma had a significant impact on graft survival rate (p=0.002, Figure 2), as well as functional success (p=0.022).
CONCLUSION
Urgent keratoplasty is a viable treatment option for cases involving an actively uncontrolled infection or corneal disease with perforation. In cases of graft rejection, bacteria, fungi, and viral pathogens were detected as causative agents, whereas only bacteria were detected as the causative agents in cases of pre and post-operative endophthalmitis. Early diagnosis and treatment play crucial roles in achieving anatomical and functional success.
PubMed: 38854901
DOI: 10.14744/bej.2024.69772 -
Cognition Jun 2024The classic Michottean 'launching' event is consistent with a real-world Newtonian elastic collision. Previous research has shown that adult humans distinguish launching...
The classic Michottean 'launching' event is consistent with a real-world Newtonian elastic collision. Previous research has shown that adult humans distinguish launching events that obey some of the physical constraints on Newtonian elastic collisions from events that do not do so early in visual processing, and that infants do so early in development (< 9 months of age). These include that in a launching event, the speed of the agent can be 3 times faster (or more) than that of the patient but the speed of the patient cannot be detectably greater than the speed of the agent. Experiment 1 shows that 7-8-month-old infants also distinguish canonical launching events from events in which the motion of the patient is rotated 90° from the trajectory of the motion of the agent (another outcome ruled out by the physics of elastic collisions). Violations of both the relative speed and the angle constraints create Michottean 'triggering' events, in which adults describe the motion of the patient as autonomous but not spontaneous, i.e., still initiated by contact with the causal agent. Experiments 2 and 3 begin to explore whether infants of this age construe Michottean triggering events as causal. We find that infants of this age are not sensitive to a reversal of the agent and patient in triggering events, thus failing to exhibit one of the signatures of representing an event as causal. We argue that there are likely several independent events schemas with causal content represented by young infants, and the literature on the origins of causal cognition in infancy would benefit from systematic investigations of event schemas other than launching events.
PubMed: 38850841
DOI: 10.1016/j.cognition.2024.105844 -
Brain Research Jun 2024Peripheral vestibular activation results in multi-level responses, from brainstem-mediated reflexes (e.g. vestibular ocular reflex - VOR) to perception of self-motion....
Peripheral vestibular activation results in multi-level responses, from brainstem-mediated reflexes (e.g. vestibular ocular reflex - VOR) to perception of self-motion. While VOR responses indicate preserved vestibular peripheral and brainstem functioning, there are no automated measures of vestibular perception of self-motion - important since some patients with brain disconnection syndromes manifest a vestibular agnosia (intact VOR but impaired self-motion perception). Electroencephalography ('EEG') - may provide a surrogate marker of vestibular perception of self-motion. A related objective is obtaining an EEG marker of vestibular sensory signal processing, distinct from vestibular-motion perception. We performed a pilot study comparing EEG responses in the dark when healthy participants sat in a vibrationless computer-controlled motorised rotating chair moving at near threshold of self-motion perception, versus a second situation in which subjects sat in the chair at rest in the dark who could be induced (or not) into falsely perceiving self-motion. In both conditions subjects could perceive self-motion perception, but in the second there was no bottom-up reflex-brainstem activation. Time-frequency analyses showed: (i) alpha frequency band activity is linked to vestibular sensory-signal activation; and (ii) theta band activity is a marker of vestibular-mediated self-motion perception. Consistent with emerging animal data, our findings support the role of theta activity in the processing of self-motion perception.
PubMed: 38844198
DOI: 10.1016/j.brainres.2024.149048 -
Journal of Vision Jun 2024The interception (or avoidance) of moving objects is a common component of various daily living tasks; however, it remains unclear whether precise alignment of foveal...
The interception (or avoidance) of moving objects is a common component of various daily living tasks; however, it remains unclear whether precise alignment of foveal vision with a target is important for motor performance. Furthermore, there has also been little examination of individual differences in visual tracking strategy and the use of anticipatory gaze adjustments. We examined the importance of in-flight tracking and predictive visual behaviors using a virtual reality environment that required participants (n = 41) to intercept tennis balls projected from one of two possible locations. Here, we explored whether different tracking strategies spontaneously arose during the task, and which were most effective. Although indices of closer in-flight tracking (pursuit gain, tracking coherence, tracking lag, and saccades) were predictive of better interception performance, these relationships were rather weak. Anticipatory gaze shifts toward the correct release location of the ball provided no benefit for subsequent interception. Nonetheless, two interceptive strategies were evident: 1) early anticipation of the ball's onset location followed by attempts to closely track the ball in flight (i.e., predictive strategy); or 2) positioning gaze between possible onset locations and then using peripheral vision to locate the moving ball (i.e., a visual pivot strategy). Despite showing much poorer in-flight foveal tracking of the ball, participants adopting a visual pivot strategy performed slightly better in the task. Overall, these results indicate that precise alignment of the fovea with the target may not be critical for interception tasks, but that observers can adopt quite varied visual guidance approaches.
Topics: Humans; Male; Female; Young Adult; Motion Perception; Adult; Individuality; Psychomotor Performance; Fixation, Ocular; Virtual Reality; Saccades; Fovea Centralis; Eye Movements
PubMed: 38842836
DOI: 10.1167/jov.24.6.4 -
Nature Communications Jun 2024Despite the profound implications of self-organization in animal groups for collective behaviors, understanding the fundamental principles and applying them to swarm...
Despite the profound implications of self-organization in animal groups for collective behaviors, understanding the fundamental principles and applying them to swarm robotics remains incomplete. Here we propose a heuristic measure of perception of motion salience (MS) to quantify relative motion changes of neighbors from first-person view. Leveraging three large bird-flocking datasets, we explore how this perception of MS relates to the structure of leader-follower (LF) relations, and further perform an individual-level correlation analysis between past perception of MS and future change rate of velocity consensus. We observe prevalence of the positive correlations in real flocks, which demonstrates that individuals will accelerate the convergence of velocity with neighbors who have higher MS. This empirical finding motivates us to introduce the concept of adaptive MS-based (AMS) interaction in swarm model. Finally, we implement AMS in a swarm of ~10 miniature robots. Swarm experiments show the significant advantage of AMS in enhancing self-organization of the swarm for smooth evacuations from confined environments.
Topics: Robotics; Animals; Birds; Motion Perception; Behavior, Animal; Motion; Flight, Animal; Social Behavior
PubMed: 38839782
DOI: 10.1038/s41467-024-49151-x -
Brain Structure & Function Jul 2024Connectivity maps are now available for the 360 cortical regions in the Human Connectome Project Multimodal Parcellation atlas. Here we add function to these maps by...
Selective activations and functional connectivities to the sight of faces, scenes, body parts and tools in visual and non-visual cortical regions leading to the human hippocampus.
Connectivity maps are now available for the 360 cortical regions in the Human Connectome Project Multimodal Parcellation atlas. Here we add function to these maps by measuring selective fMRI activations and functional connectivity increases to stationary visual stimuli of faces, scenes, body parts and tools from 956 HCP participants. Faces activate regions in the ventrolateral visual cortical stream (FFC), in the superior temporal sulcus (STS) visual stream for face and head motion; and inferior parietal visual (PGi) and somatosensory (PF) regions. Scenes activate ventromedial visual stream VMV and PHA regions in the parahippocampal scene area; medial (7m) and lateral parietal (PGp) regions; and the reward-related medial orbitofrontal cortex. Body parts activate the inferior temporal cortex object regions (TE1p, TE2p); but also visual motion regions (MT, MST, FST); and the inferior parietal visual (PGi, PGs) and somatosensory (PF) regions; and the unpleasant-related lateral orbitofrontal cortex. Tools activate an intermediate ventral stream area (VMV3, VVC, PHA3); visual motion regions (FST); somatosensory (1, 2); and auditory (A4, A5) cortical regions. The findings add function to cortical connectivity maps; and show how stationary visual stimuli activate other cortical regions related to their associations, including visual motion, somatosensory, auditory, semantic, and orbitofrontal cortex value-related, regions.
Topics: Humans; Magnetic Resonance Imaging; Male; Female; Adult; Brain Mapping; Hippocampus; Young Adult; Photic Stimulation; Connectome; Face; Neural Pathways; Visual Cortex; Visual Perception; Pattern Recognition, Visual
PubMed: 38839620
DOI: 10.1007/s00429-024-02811-6 -
ENeuro Jun 2024How features of complex visual patterns are combined to drive perception and eye movements is not well understood. Here we simultaneously assessed human observers'...
How features of complex visual patterns are combined to drive perception and eye movements is not well understood. Here we simultaneously assessed human observers' perceptual direction estimates and ocular following responses (OFR) evoked by moving plaids made from two summed gratings with varying contrast ratios. When the gratings were of equal contrast, observers' eye movements and perceptual reports followed the motion of the plaid pattern. However, when the contrasts were unequal, eye movements and reports during early phases of the OFR were biased toward the direction of the high-contrast grating component; during later phases, both responses followed the plaid pattern direction. The shift from component- to pattern-driven behavior resembles the shift in tuning seen under similar conditions in neuronal responses recorded from monkey MT. Moreover, for some conditions, pattern tracking and perceptual reports were correlated on a trial-by-trial basis. The OFR may therefore provide a precise behavioral readout of the dynamics of neural motion integration for complex visual patterns.
Topics: Motion Perception; Humans; Eye Movements; Photic Stimulation; Male; Female; Adult; Young Adult; Pattern Recognition, Visual
PubMed: 38834301
DOI: 10.1523/ENEURO.0204-24.2024 -
Proceedings of the National Academy of... Jun 2024Human pose, defined as the spatial relationships between body parts, carries instrumental information supporting the understanding of motion and action of a person. A...
Human pose, defined as the spatial relationships between body parts, carries instrumental information supporting the understanding of motion and action of a person. A substantial body of previous work has identified cortical areas responsive to images of bodies and different body parts. However, the neural basis underlying the visual perception of body part relationships has received less attention. To broaden our understanding of body perception, we analyzed high-resolution fMRI responses to a wide range of poses from over 4,000 complex natural scenes. Using ground-truth annotations and an application of three-dimensional (3D) pose reconstruction algorithms, we compared similarity patterns of cortical activity with similarity patterns built from human pose models with different levels of depth availability and viewpoint dependency. Targeting the challenge of explaining variance in complex natural image responses with interpretable models, we achieved statistically significant correlations between pose models and cortical activity patterns (though performance levels are substantially lower than the noise ceiling). We found that the 3D view-independent pose model, compared with two-dimensional models, better captures the activation from distinct cortical areas, including the right posterior superior temporal sulcus (pSTS). These areas, together with other pose-selective regions in the LOTC, form a broader, distributed cortical network with greater view-tolerance in more anterior patches. We interpret these findings in light of the computational complexity of natural body images, the wide range of visual tasks supported by pose structures, and possible shared principles for view-invariant processing between articulated objects and ordinary, rigid objects.
Topics: Humans; Magnetic Resonance Imaging; Male; Female; Adult; Brain; Brain Mapping; Visual Perception; Posture; Young Adult; Imaging, Three-Dimensional; Photic Stimulation; Algorithms
PubMed: 38830105
DOI: 10.1073/pnas.2317707121 -
Scientific Reports Jun 2024When lying inside a MRI scanner and even in the absence of any motion, the static magnetic field of MRI scanners induces a magneto-hydrodynamic stimulation of subjects'...
When lying inside a MRI scanner and even in the absence of any motion, the static magnetic field of MRI scanners induces a magneto-hydrodynamic stimulation of subjects' vestibular organ (MVS). MVS thereby not only causes a horizontal vestibular nystagmus but also induces a horizontal bias in spatial attention. In this study, we aimed to determine the time course of MVS-induced biases in both VOR and spatial attention inside a 3 T MRI-scanner as well as their respective aftereffects after participants left the scanner. Eye movements and overt spatial attention in a visual search task were assessed in healthy volunteers before, during, and after a one-hour MVS period. All participants exhibited a VOR inside the scanner, which declined over time but never vanished completely. Importantly, there was also an MVS-induced horizontal bias in spatial attention and exploration, which persisted throughout the entire hour within the scanner. Upon exiting the scanner, we observed aftereffects in the opposite direction manifested in both the VOR and in spatial attention, which were statistically no longer detectable after 7 min. Sustained MVS effects on spatial attention have important implications for the design and interpretation of fMRI-studies and for the development of therapeutic interventions counteracting spatial neglect.
Topics: Humans; Magnetic Resonance Imaging; Male; Female; Adult; Attention; Eye Movements; Young Adult; Reflex, Vestibulo-Ocular; Space Perception; Vestibule, Labyrinth; Healthy Volunteers
PubMed: 38825633
DOI: 10.1038/s41598-024-62981-5 -
ENeuro Jun 2024Animals use a combination of eye movements to track moving objects. These different eye movements need to be coordinated for successful tracking, requiring interactions...
Animals use a combination of eye movements to track moving objects. These different eye movements need to be coordinated for successful tracking, requiring interactions between the systems involved. Here, we study the interaction between the saccadic and smooth pursuit eye movement systems in marmosets. Using a single-target pursuit task, we show that saccades cause an enhancement in pursuit following a saccade. Using a two-target pursuit task, we show that this enhancement in pursuit is selective toward the motion of the target selected by the saccade, irrespective of any biases in pursuit prior to the saccade. These experiments highlight the similarities in the functioning of saccadic and smooth pursuit eye movement systems across primates.
Topics: Animals; Callithrix; Pursuit, Smooth; Saccades; Male; Female; Photic Stimulation; Motion Perception
PubMed: 38821872
DOI: 10.1523/ENEURO.0027-24.2024