Duration Of Motion Aftereffect Research Articles

Contribution of the slow motion mechanism to global motion revealed by an MAE technique

Two different motion mechanisms have been identified with motion aftereffect (MAE). (1) A slow motion mechanism, accessed by a static MAE, is sensitive to high-spatial and low-temporal frequency; (2) a fast motion mechanism, accessed by a flicker MAE, is sensitive to low-spatial and high-temporal frequency. We examined their respective responses to global motion after adapting to a global motion pattern constructed of multiple compound Gabor patches arranged circularly. Each compound Gabor patch contained two gratings at different spatial frequencies (0.53 and 2.13 cpd) drifting in opposite directions. The participants reported the direction and duration of the MAE for a variety of global motion patterns. We discovered that static MAE durations depended on the global motion patterns, e.g., longer MAE duration to patches arranged to see rotation than to random motion (Exp 1), and increase with global motion strength (patch number in Exp 2). In contrast, flicker MAEs durations are similar across different patterns and adaptation strength. Further, the global integration occurred at the adaptation stage, rather than at the test stage (Exp 3). These results suggest that slow motion mechanism, assessed by static MAE, integrate motion signals over space while fast motion mechanisms do not, at least under the conditions used.

Does audible sound modulate the potency of visual motion when that motion is suppressed from awareness by continuous flash suppression?

Audible sounds naturally associated with specific visual stimuli can potentiate awareness of those stimuli during binocular rivalry (Chen et al., 2011; Lee, M., et al., 2015), implying formation of semantically congruent multisensory associations outside of awareness. Is awareness required for establishment of multisensory congruence between low-level sensory information? We have utilized the translational motion aftereffect (MAE) putatively mediated by direction-selective neurons and known to be attenuated by interocular suppression (Blake et al., 2006). MAEs were generated by 8-sec presentations of a pair of monocularly viewed, vertical gabor patterns comprising separate parts above and below central fixation. One pattern moved either leftward or rightward and the other remained stationary. For the visible adaptation condition, MAE contrast dependence was measured over a 1.5-log unit range, allowing selection of a non-saturated contrast for the main experiment. For the invisible adaptation condition, both gabor patterns were reliably rendered invisible by interocular continuous flash suppression (CFS; Tsuchiya & Koch, 2005). Leftward or rightward moving sound was mimicked by varying interaural intensity differences in white noise presented over headphones. Audiovisual motion could be either congruent or incongruent in direction, but owing to the potency of CFS participants were unaware of the congruence and of the location of moving gabor pattern. Following adaptation period, participants reported the duration, location (top vs bottom) and direction (leftward vs rightward) of the MAE experienced while viewing stationary gabor patterns. Among the five participants exhibiting clear dependence of MAE on gabor contrast, all showed reduced MAE duration when adaptation motion was suppressed by CFS. Of relevance to our question, MAE duration in the congruent condition was longer than in the incongruent condition, and no MAE was experienced on 26% of incongruent trials but only 15% of congruent trials. These results suggest that the low-level multisensory representations can be formed outside awareness. Meeting abstract presented at VSS 2018

Opposite effects of high- and low-frequency transcranial random noise stimulation probed with visual motion adaptation.

Transcranial random noise stimulation (tRNS) is a recent neuro-modulation technique whose effects at both behavioural and neural level are still debated. Here we employed the well-known phenomenon of motion after-effect (MAE) in order to investigate the effects of high- vs. low-frequency tRNS on motion adaptation and recovery. Participants were asked to estimate the MAE duration following prolonged adaptation (20 s) to a complex moving pattern, while being stimulated with either sham or tRNS across different blocks. Different groups were administered with either high- or low-frequency tRNS. Stimulation sites were either bilateral human MT complex (hMT+) or frontal areas. The results showed that, whereas no effects on MAE duration were induced by stimulating frontal areas, when applied to the bilateral hMT+, high-frequency tRNS caused a significant decrease in MAE duration whereas low-frequency tRNS caused a significant corresponding increase in MAE duration. These findings indicate that high- and low-frequency tRNS have opposed effects on the adaptation-dependent unbalance between neurons tuned to opposite motion directions, and thus on neuronal excitability.

Visual motion processing in migraine: Enhanced motion after-effects are related to display contrast, visual symptoms, visual triggers and attack frequency.

Background Visual after-effects are illusions that occur after prolonged viewing of visual displays. The motion after-effect (MAE), for example, is an illusory impression of motion after viewing moving displays: subsequently, stationary displays appear to drift in the opposite direction. After-effects have been used extensively in basic vision research and in clinical settings, and are enhanced in migraine. Objective The objective of this article is to assess associations between ( 1 ) MAE duration and visual symptoms experienced during/between migraine/headache attacks, and ( 2 ) visual stimuli reported as migraine/headache triggers. Methods The MAE was elicited after viewing motion for 45 seconds. MAE duration was tested for three test contrast displays (high, medium, low). Participants also completed a headache questionnaire that included migraine/headache triggers. Results For each test contrast, the MAE was prolonged in migraine. MAE duration was associated with photophobia; visual triggers (flicker, striped patterns); and migraine or headache frequency. Conclusions Group differences on various visual tasks have been attributed to abnormal cortical processing in migraine, such as hyperexcitability, heightened responsiveness and/or a lack of intra-cortical inhibition. The results are not consistent with hyperexcitability simply from a general lack of inhibition. Alternative multi-stage models are discussed and suggestions for further research are recommended, including visual tests in clinical assessments/clinical trials.

Motion-form interactions beyond the motion integration level: evidence for interactions between orientation and optic flow signals.

Motion and form encoding are closely coupled in the visual system. A number of physiological studies have shown that neurons in the striate and extrastriate cortex (e.g., V1 and MT) are selective for motion direction parallel to their preferred orientation, but some neurons also respond to motion orthogonal to their preferred spatial orientation. Recent psychophysical research (Mather, Pavan, Bellacosa, & Casco, 2012) has demonstrated that the strength of adaptation to two fields of transparently moving dots is modulated by simultaneously presented orientation signals, suggesting that the interaction occurs at the level of motion integrating receptive fields in the extrastriate cortex. In the present psychophysical study, we investigated whether motion-form interactions take place at a higher level of neural processing where optic flow components are extracted. In Experiment 1, we measured the duration of the motion aftereffect (MAE) generated by contracting or expanding dot fields in the presence of either radial (parallel) or concentric (orthogonal) counterphase pedestal gratings. To tap the stage at which optic flow is extracted, we measured the duration of the phantom MAE (Weisstein, Maguire, & Berbaum, 1977) in which we adapted and tested different parts of the visual field, with orientation signals presented either in the adapting (Experiment 2) or nonadapting (Experiments 3 and 4) sectors. Overall, the results showed that motion adaptation is suppressed most by orientation signals orthogonal to optic flow direction, suggesting that motion-form interactions also take place at the global motion level where optic flow is extracted.

Static Gratings Modulate Motion After-Effect Duration but Not Direction

Motion after-effect (MAE) duration was measured after adapting to a dot field drifting transparently over a static grating. Duration was shorter when the grating was oriented orthogonally to the direction of the dot field than when it was oriented parallel to the direction of the dot field. After bi-directional adaptation involving two transparently drifting dot fields, the effect of the grating on MAE duration depended on its orientation with respect to the combined direction of the two fields, not with respect to the direction of the two component directions. On the other hand, changes in grating orientation had no effect on the apparent direction of the MAE from bi-directional adaptation. The effect of grating orientation on MAE duration is consistent with ‘motion-streak’ interactions between motion and form processes, which favour motion signals parallel to local orientation signals. Results obtained with bi-directional adapting stimuli indicate that the interactions occur after the point at which component motion signals are combined to compute pattern direction.

Psychophysical evidence for interactions between visual motion and form processing at the level of motion integrating receptive fields

Recent physiological and psychophysical research has challenged the traditional view that motion and form information are processed in distinct, parallel pathways in the visual system. Rapid movement creates ‘motion-streaks’ parallel to the motion trajectory, which facilitate motion detection. Some motion-selective neurons in striate and extrastriate cortex are sensitive to motion parallel to their preferred orientation, a possible neural substrate of motion-streak effects. As a psychophysical test of the cortical site of motion–form interactions, four experiments measured the duration and direction of the motion after-effect (MAE) generated by drifting dot fields in the presence of either vertical, horizontal or oblique counter-phase pedestal gratings. In Experiment 1 a single, horizontally drifting dot field was used; motion streak interactions predict stronger after-effects for horizontal gratings. Experiment 2 employed two transparently drifting dot fields (obliquely upwards and downwards), which produce a horizontal MAE. If motion–form interactions depend only on individual dot field trajectory, there should be no effect of grating orientation on MAEs after bi-directional adaptation. MAEs from both uni-directional and bi-directional adaptation were stronger using horizontal gratings than using vertical gratings. Experiments 3 and 4 found that an oblique pedestal did not alter the apparent direction of the MAE from bi-directional motion, despite the fact that it reduced MAE duration compared to a parallel pedestal. These results provide new evidence that the strength of adaptation to motion is affected by simultaneously presented orientation signals, and implicate motion integrating receptive fields in extrastriate cortex as the likely neural locus of this motion–form interaction.

Motion aftereffect duration is not changed by perceptual learning: Evidence against the representation modification hypothesis

The representation modification hypothesis of perceptual learning attributes the practice-induced improvements in sensitivity and/or discriminability to changes in the early visual areas. We used motion aftereffects (MAE) to probe the representations of motion direction. In two experiments, four practice sessions on a fine direction-discrimination task caused large stimulus-specific improvements in d′ but no significant stimulus-specific changes in either static or dynamic MAE duration at posttest relative to a pretest. Power analysis indicated that the data were approximately 100 times more likely given the hypothesis of no MAE change than the hypothesis of a 10% relative change. In light of converging evidence in the MAE literature, this suggests that little or no change occurred in the cortical representations of visual motion up to and including area MT. The task specificity of the learning effect challenges the representation modification hypothesis and supports an alternative—selective reweighting.

A motion-energy model predicts the direction discrimination and MAE duration of two-stroke apparent motion at high and low retinal illuminance

Two-stroke apparent motion offers a challenge to current theoretical models of motion processing and is thus a useful tool for investigating motion sensor input. The stimulus involves repeated presentation of two pattern frames containing a spatial displacement, with a blank inter-stimulus interval (ISI) at one of the two-frame transitions. The resulting impression of continuous motion was measured here using both direction discrimination and motion after-effect duration in order to assess the extent to which data using the two measures can be explained by a computational model without reference to attentive tracking mechanisms. The motion-energy model was found to offer a very good account of the psychophysical data using similar parameters for both tasks. The experiment was run under both photopic and scotopic retinal illumination. Data revealed that the optimum ISI for perceiving two-stroke apparent motion shifts to longer ISIs under scotopic conditions, providing evidence for a biphasic impulse response at low luminance. Best-fitting model parameters indicate that motion sensors receive inputs from temporal filters whose central temporal frequency shifts from 2.5 to 3.0Hz at high retinal illuminance to 1.0–1.5Hz at low retinal illuminance.

The effects of selective attention to first- and second-order motion stimuli on motion aftereffect duration

The effects of selective attention to first- and second-order motion stimuli on motion aftereffect duration

Visual adaptation reveals asymmetric spatial frequency tuning for motion

This study investigated the spatial frequency selectivity of the human visual motion system using the technique of adaptation in which motion aftereffect (MAE) duration was taken as an index of aftereffect magnitude. Eight observers adapted to two vertically oriented, oppositely drifting, luminance-defined gratings that were spatially separated in the vertical dimension. The spatial frequency of the adaptation patterns spanned a 3-octave range (0.25 to 2 c/deg) and drifted at 5 Hz. Following adaptation (20 s), two stationary test patterns were presented and MAE duration was measured. The spatial frequency difference between the adaptation and test patterns was varied from -2.5 to 2.5 octaves in 0.5 octave steps. MAE tuning functions at the lowest adaptation frequency (0.25 c/deg) were bandpass and reasonably symmetric. However, as the spatial frequency of the adaptation patterns increased, overall MAE duration decreased and the shape of the tuning functions became markedly asymmetric. This asymmetry was characterized by a MAE peak that was centered approximately 1 octave below the adaptation frequency. The results are consistent with recent masking studies (C. V. Hutchinson & T. Ledgeway, 2007) and may reflect either asymmetric spatial frequency selectivity of underlying motion units or frequency-specific interactions (e.g. inhibition) between motion sensors tuned to different spatial frequencies.

Spatial and Temporal Frequency Tuning of Motion-in-Depth Aftereffect

In this study, we examined the spatial and temporal frequency tuning of motion-in-depth aftereffect. We changed the spatial frequency of test stimuli and temporal frequency of adapting stimuli to investigate the influence on the motion aftereffect duration. It was found that, in spite of the change of spatial frequency of test stimuli, the maximum motion aftereffect duration was measured when the mean temporal frequency of adapting stimuli was set to 3.83 Hz. On the other hand, in spite of the change of temporal frequency of adapting stimuli, the maximum motion aftereffect duration was measured when the mean spatial frequency of test stimuli was set to 0.40 cycles/degree. We also changed the moving direction of adapting stimuli in approaching and receding directions to investigate the moving direction influence on the motion aftereffect duration. It was noted that compared to the approaching motion, longer motion aftereffect duration was measured for the receding motion.

The tactile motion aftereffect revisited

In two experiments, we measured the direction, duration, frequency, and vividness of the tactile motion aftereffect (MAE) induced by a rotating drum with a ridged surface. In Experiment 1, we adapted the: (1) fingers and palm, including the thumb, (2) fingers and palm, excluding the thumb, and (3) fingers only, excluding the thumb. In each condition the drum rotated at 60 rpm for 120 s. There was no difference in duration, frequency, or vividness between the skin surfaces tested. In Experiment 2, we tested several adapting speeds: 15, 30, 45, 60, and 75 rpm. At each speed the fingers and palm, excluding the thumb, were adapted for 120 s. The duration, frequency, and vividness of the tactile MAE increased linearly with adapting speed. Overall, the tactile MAE was reported on approximately half of the trials, suggesting that it is not as robust as its visual counterpart.

Effects of spatial attention and salience cues on chromatic and achromatic motion processing

While several previous psychophysical and neurophysiological studies have demonstrated chromatic (red/green) input to motion processing, the nature of this input is still a matter of debate. In particular, there exists controversy as to whether chromatic motion processing is mediated by low-level motion mechanisms versus higher-level, attention- or salience-based mechanisms. To address the role of attention, in Experiment 1, we asked whether spatial attention exerts larger effects on chromatic (red/green), as compared to achromatic, motion. To this end, we employed a motion after-effect (MAE) paradigm, and measured attention effects by comparing MAE duration between conditions where subjects attended to the adapting moving grating stimulus versus ignored that stimulus because they were required to perform an attentionally demanding vowel detection task at the center of gaze. The results from these experiments revealed equal effects of spatial attention on chromatic and achromatic motion processing, which were essentially constant (roughly 1.4-fold) across a wide range of stimulus contrasts (3.2–25% cone contrast). These findings suggest that chromatic motion processing is not affected disproportionally by higher-level spatial attention mechanisms. To address the role of salience, in Experiment 2, we investigated the effects of bottom–up salience cues on the strength of chromatic and achromatic motion, as measured with the MAE. Salience was manipulated by varying the relationship between the moving gratings and the background color. The results of these experiments revealed small and insignificant effects of salience cues on chromatic and achromatic motion processing. These findings suggest that mechanisms sensitive to feature salience do not influence low-level chromatic motion mechanisms mediating the motion after-effect.

運動残効による視覚系疲労の評価方法の検討

In order to develop the effective evaluation system for the fatigue of operator's visual system in long term operation, the experiments were carried out utilizing perceptual time duration of motion aftereffect (MAE), critical flicker frequency (CFF) and the near point (NP) measurement. The MAE was measured using rotated spiral figure displayed on a CRT screen. To generate visual fatigue, a signal detection task in randomly displayed alphabets was used. After the task, MAE duration, CFF and NP were increased. It is supposed that the visual fatigue generated by the experimental task affects motion processing system of visual cortex. Results suggest that the MAE can be an effective tool for visual fatigue evaluation.

Adaptation to spiral motion: global but not local motion detectors are modulated by attention

In this study, we investigated the effect of attention on local motion detectors. For this purpose we used logarithmic spirals previously used by Cavanagh and Favreau [ Perception, 1980, 9(2), 175–182]. While the adapting stimulus was a rotating logarithmic spiral, the test stimulus was either the same spiral or its mirror image. When superimposed, all contours of the spiral stimulus and its mirror image are 90° apart. Presenting the same spiral during the test period shows adaptation of both local motion detectors and global rotation detectors, whereas showing the mirror-spiral stimulates another set of local motion detectors, and therefore illustrates adaptation at only the global motion level. To manipulate the attentional state of observers, a secondary task was presented during the adaptation phase and observers either performed the task or ignored it. Motion aftereffect (MAE) duration was measured afterwards. While the effects of attention and test stimulus type on MAE duration were both significant, the difference in the MAE strength between the attention-distracted and attention-not-distracted conditions was equal when the test stimulus was the same-spiral or the mirror-spiral, suggesting that attention to spiral motion modulates only global rotation units and does not affect local motion detectors located at V1. Our results are in accord with those reported by Watanabe et al. [ Proceedings of the National Academy of Sciences of the USA, 1998, 95(19), 11489–11492] which showed differential modulation of motion processing areas depending on the type of motion being attended. Therefore our data are supportive of the notion that attentional modulation of V1 is highly task-dependent.

Direct current stimulation over MT+/V5 modulates motion aftereffect in humans

While there is strong evidence for the central role of the human MT+/V5 in motion processing, its involvement in motion adaptation is still the subject of debate. We used transcranial direct current stimulation (tDCS) to test whether MT+/V5 is part of the neural network involved in the long-term adaptation-induced motion after-effect in humans. It was found that both cathodal and anodal stimulation over MT+/V5 resulted in a significant reduction of the perceived motion after-effect duration, but had no effect on performance in a luminance-change-detection task used to determine attentional load during adaptation. Our control experiment excluded the possibility that the observed MT+/V5 stimulation effects were due to a diffused modulation of the early cortical areas, i.e. by the stimulation applied over MT+/V5. These results provide evidence that external modulation of neural excitability in human MT+/V5 affects the strength of perceived motion after-effect and support the involvement of MT+/V5 in motion adaptation processes.

Attention enhances adaptability: evidence from motion adaptation experiments

Several previous psychophysical and neurophysiological studies have investigated the separate effects of attention and adaptation on visual processing. Here, we investigated the combined effects of attention and adaptation on motion processing by measuring the effects of spatial attention on the duration of the motion after-effect (MAE) over a wide range of stimulus contrasts. MAE duration was compared between two conditions: full-attention, subjects were required to pay attention to the adapting motion stimulus, and poor-attention, subjects performed a difficult vowel detection task at the center of gaze and ignored the adapting motion stimulus. Attention was found to increase the MAE duration by a factor of 1.4, which was approximately constant over a wide range of stimulus contrasts (3.22–80.6%). Notably, this included contrasts for which the MAE duration had reached its asymptotic value. We show that a quantitative model based on known properties of directionally selective MT neurons can explain these results by assuming that attention enhances the effects of adaptation, a phenomenon we refer to as “ adaptation gain”. Specifically, attending to an adapting motion stimulus shifts the semi-saturation point ( C 50) of the underlying contrast response function (CRF) of motion detectors roughly 1.4-fold more to the right than does ignoring that same stimulus. By enhancing the effects of adaptation in this fashion, attention is predicted to enhance the adaptability of the visual motion system.

A gain-control model relating nulling results to the duration of dynamic motion aftereffects

Strength of the motion aftereffect (MAE) is most often quantified by its duration, a high-variance and rather ‘subjective’ measure. With the help of an automatic gain-control model we quantitatively relate nulling-thresholds, adaptation strength, direction discrimination threshold, and duration of the dynamic MAE (dMAE). This shows how the nulling threshold, a more objective two-alternative forced-choice measure, relates to the same system property as MAE-durations. Two psychophysical experiments to test the model use moving random-pixel-arrays with an adjustable luminance signal-to-noise ratio. We measure MAE-duration as a function of adaptation strength and compare the results to the model prediction. We then do the same for nulling-thresholds. Model predictions are strongly supported by the psychophysical findings. In a third experiment we test formulae coupling nulling threshold, MAE-duration, and direction-discrimination thresholds, by measuring these quantities as a function of speed. For the medium-to-high speed range of these experiments we found that nulling thresholds increase and dMAE-durations decrease about linearly, whereas direction discrimination thresholds increase exponentially with speed. The model description then suggests that the motion-gain decreases, while the noise-gain and model’s threshold increase with speed.

Auditory and visual attention modulate motion processing in area MT+

Behavioral and physiological studies have established that visual attention to a given feature or location can modulate early visual processing. In the present experiment, we asked whether auditory attention can likewise influence visual processing. We used a visual illusion, the motion aftereffect (MAE), to assess the effects of visual and auditory attention on motion processing in human area MT+. We acquired psychophysical and functional magnetic resonance imaging (fMRI) data while subjects fixated and viewed moving and stationary stimuli in alternating blocks. For each of four motion conditions, we measured the duration of the subsequent MAE, the time for activity in MT+ to return to baseline after motion adaptation (decay time), and the magnitude of MT+ activity during motion adaptation. For each subject, we first obtained measures of motion processing in the absence of attentional demands, by comparing reversing and expanding motion conditions. Subjects perceived the MAE following adaptation to expanding but not reversing motion, as observed previously, and decay times in MT+ were selectively prolonged after expanding motion. We then assessed the effects of performing either a visual or an auditory attentional task during expanding motion adaptation. Performance of the attentional task, whether visual or auditory, produced a significant reduction of subsequent MAE perception and associated decay times in MT+, as compared to expanding motion with fixation only. Both attentional tasks also reduced the magnitude of activation during motion adaptation. These data show that auditory attention, like visual attention, can modify sensory processing at a remarkably early stage of the visual hierarchy.