Psychophysical Reverse Correlation Revealed Broader Orientation Tuning and Prolonged Reaction Time in Amblyopia

Abstract

Purpose Neural selectivity of orientation is a fundamental property of visual system. We aim to investigate whether and how the orientation selectivity changes in amblyopia. Methods Seventeen patients with amblyopia (27.1 ± 7.1 years) and 18 healthy participants (25.1 ± 2.7 years) took part in this study. They were asked to continuously detect vertical gratings embedded in a stream of randomly oriented gratings. Using a technique of subspace reverse correlation, the orientation-time perceptive field (PF) for the atypical grating detection task was derived for each participant. Detailed comparisons were made between the PFs measured with the amblyopic and healthy eyes. Results The PF of the amblyopic eyes showed significant differences in orientation and time domain compared with that of the normal eyes (cluster-based permutation test, p s < 0.05), with broader bandwidth of orientation tuning (31.41 ± 10.59 degrees [mean ± SD] vs. 24.76 ± 6.85 degrees, P = 0.039) and delayed temporal dynamics (483 ± 68 ms vs. 425 ± 58 ms, P = 0.015). None of the altered PF properties correlated with the contrast sensitivity at 1 cycle per degree (c/deg) in amblyopia. No difference in PFs between the dominant and non-dominant eyes in the healthy group was found. Conclusions The altered orientation-time PF to the low spatial frequency and high contrast stimuli suggests amblyopes had coarser orientation selectivity and prolonged reaction time. The broader orientation tuning probably reflects the abnormal lateral interaction in the primary visual cortex, whereas the temporal delay might indicate a high level deficit.

Decomposing the Response Time in Amblyopia: A Drift Diffusion Model Analysis

“… 59 , 60 Given that Ter s in both AE and FE were found to be increased, we speculate that the prolonged Ter is more likely reflecting the deficits in the post-sensory processes that are outside V1 in amblyopia. Our speculation agrees with the result from other amblyopia studies in manual response time 61 and in saccadic delay. 21 , 62 People have also suggested that amblyopia impaired attention 12 , 63 and may impact cortical connections to higher brain areas, including parietal and frontal cortices.…”

Visual Tracking in Amblyopia: A Continuous Psychophysical Approach

“…In contrast, the continuous tracking paradigm has a long stream of dynamic stimuli with simultaneous response collection and thus is capable of collecting multiple responses within a second. 24 – 27 , 33 , 50 It has been shown that the continuous tracking paradigm can provide the psychophysical measure equivalent to that in a conventional trial-based paradigm 24 , 26 with similar precision but in a shorter time (120 tracking trials vs. 4860 discrete trials). 24 In addition, the continuous tracking task is more natural compared to the repetitive conventional trials because our daily visual tasks such as driving or looking for a familiar face in the crowded street are rarely discrete.…”

“…The high-throughput stimulus–response data series generated by the continuous tracking paradigm allowed us to apply cross-correlation to study human tracking in a more rigorous manner. 24 , 25 , 33 , 53 Cross-correlation has been widely used in the analysis of neural data to reveal the neuron receptive fields in physiology. 28 , 30 – 32 It has also been employed to uncover the spatiotemporal weighting functions of sensory processes in psychophysics, such as orientation tuning, 33 , 54 disparity tuning, 55 perceptual template, 56 , 57 eye movement, 50 and face recognition.…”

“…1 F). Considering the observer as a linear system with the target displacement as input and the mouse response as output, the cross-correlation between the displacements of the target and mouse is the impulse response function or the kernel of the system, 24 , 28 , 33 , 50 which can fully characterize the system. In a single trial, the horizontal and vertical components of the trajectory data were separately analyzed ( Figs.…”

“…The continuous psychophysical paradigm, a newly developed computer-based method that allows precise manipulation of visual input, 24 – 27 could serve a potential tool to investigate the visuomotor control. By asking participants to continuously track a stimulus varying in certain feature space during a long time, the paradigm generates high-throughput time-series data enables us to perform cross-correlation analysis to relate the behavioral response to the input 28 – 33 and to reveal the temporal dynamics of the biological system. It has been demonstrated that the paradigm can provide the same measure as the classic trial-based forced-choice paradigm with a higher efficiency.…”