Geertsenlester9382

We conclude that face stimuli can evoke fast saccadic and manual responses when projected to the K pathway.We investigated the relationship between eyes receiving visual input of large field translating random dot motion and subsequent reflexive changes in running direction in mice. The animals were head-fixed running on a Styrofoam ball and the opto-locomotor reflex (OLR) was measured in response to 2 s of dots patterns moving horizontally to the left or right. We measured the OLR in conditions with both eyes open (binocular) and one eye closed (monocular). When we covered the right or left eye in the monocular condition, we found reflexive behavior to be delayed for a few hundred milliseconds to leftward or rightward motion, respectively. After this delay, the bias disappeared and reflexive behavior was similar to responses to motion under binocular conditions. These results might be explained by different contributions of subcortical and cortical visual motion processing pathways to the OLR. Furthermore, we found no evidence for nonlinear interactions between the two eyes, because the sum of the OLR of the two monocular conditions was equal in amplitude and temporal characteristics to the OLR under binocular conditions.In a reverse-phi stimulus, the contrast luminance of moving dots is reversed each displacement step. Under those conditions, the direction of the moving dots is perceived in the direction opposite of the displacement direction of the dots. In this study, we investigate if mice respond oppositely to phi and reverse-phi stimuli. Mice ran head-fixed on a Styrofoam ball floating on pressurized air at the center of a large dome. We projected random dot patterns that were displaced rightward or leftward, using either a phi or a reverse-phi stimulus. For phi stimuli, changes in direction caused the mice to reflexively compensate and adjust their running direction in the direction of the displaced pattern. We show that for reverse-phi stimuli mice compensate in the direction opposite to the displacement direction of the dots, in accordance with the perceived direction of displacement in humans for reverse-phi stimuli.Perceptual learning, which improves stimulus discrimination, typically results from training with a single stimulus condition. read more Two major learning mechanisms, early cortical neural plasticity and response reweighting, have been proposed. Here we report a new format of perceptual learning that by design may have bypassed these mechanisms. Instead, it is more likely based on abstracted stimulus evidence from multiple stimulus conditions. Specifically, we had observers practice orientation discrimination with Gabors or symmetric dot patterns at up to 47 random or rotating location × orientation conditions. Although each condition received sparse trials (12 trials/session), the practice produced significant orientation learning. Learning also transferred to a Gabor at a single untrained condition with two- to three-times lower orientation thresholds. Moreover, practicing a single stimulus condition with matched trial frequency (12 trials/session) failed to produce significant learning. These results suggest that learning with multiple stimulus conditions may not come from early cortical plasticity or response reweighting with each particular condition. Rather, it may materialize through a new format of perceptual learning, in which orientation evidence invariant to particular orientations and locations is first abstracted from multiple stimulus conditions and then reweighted by later learning mechanisms. The coarse-to-fine transfer of orientation learning from multiple Gabors or symmetric dot patterns to a single Gabor also suggest the involvement of orientation concept learning by the learning mechanisms.Humans and other animals move their eyes in anticipation to compensate for sensorimotor delays. Such anticipatory eye movements can be driven by the expectation of a future visual object or event. Here we investigate whether such anticipatory responses extend to ocular torsion, the eyes' rotation about the line of sight. We recorded three-dimensional eye position in head-fixed healthy human adults who tracked a rotating dot pattern moving horizontally across a computer screen. This kind of stimulus triggers smooth pursuit with a horizontal and torsional component. In three experiments, we elicited expectation of stimulus rotation by repeatedly showing the same rotation (Experiment 1), or by using different types of higher-level symbolic cues indicating the rotation of the upcoming target (Experiments 2 and 3). Across all experiments, results reveal reliable anticipatory horizontal smooth pursuit. However, anticipatory torsion was only elicited by stimulus repetition, but not by symbolic cues. In summary, torsion can be made in anticipation of an upcoming visual event only when low-level motion signals are accumulated by repetition. Higher-level cognitive mechanisms related to a symbolic cue reliably evoke anticipatory pursuit but did not modulate torsion. These findings indicate that anticipatory torsion and anticipatory pursuit are at least partly decoupled and might be controlled separately.Purpose To test the hypothesis that emmetropization buffers against genetic and environmental risk factors for myopia by investigating whether risk factor effect sizes vary depending on children's position in the refractive error distribution. Methods Refractive error was assessed in participants from two birth cohorts Avon Longitudinal Study of Parents and Children (ALSPAC) (noncycloplegic autorefraction) and Generation R (cycloplegic autorefraction). A genetic risk score for myopia was calculated from genotypes at 146 loci. Time spent reading, time outdoors, and parental myopia were ascertained from parent-completed questionnaires. Risk factors were coded as binary variables (0 = low, 1 = high risk). Associations between refractive error and each risk factor were estimated using either ordinary least squares (OLS) regression or quantile regression. Results Quantile regression effects associated with all risk factors (genetic risk, parental myopia, high time spent reading, low time outdoors) were larger for children in the extremes of the refractive error distribution than for emmetropes and low ametropes in the center of the distribution.