The role of eye-specific attention in ocular dominance plasticity.

It is well known how selective attention biases information processing in real time, but few work investigates the aftereffects of prolonged attention, let alone the underlying neural mechanisms. To examine perceptual aftereffect after prolonged attention to a monocular pathway, movie images played normally were presented to normal adult's one eye (attended eye), while movie images of the same episode but played backwards were presented to the opposite eye (unattended eye). One hour of watching this dichoptic movie caused a shift of perceptual ocular dominance towards the unattended eye. Interestingly, the aftereffect positively correlated with the advantage of neural activity for the attended-eye over unattended-eye signals at the frontal electrodes measured with steady-state visual evoked potentials. Moreover, the aftereffect disappeared when interocular competition was minimized during adaptation. These results suggest that top-down eye-specific attention can induce ocular dominance plasticity through binocular rivalry mechanisms. The present study opens the route to explain at least part of short-term ocular dominance plasticity with the ocular-opponency-neuron model, which may be an interesting complement to the homeostatic compensation theory.

Impact of relative and absolute values on orienting attention in time.

Reward has been known to render the reward-associated stimulus more salient to block effective attentional orienting in space. However, whether and how reward influences goal-directed attention in time remains unclear. Here, we used a modified attentional cueing paradigm to explore the effect of reward on temporal attention, in which the valid targets were given a low monetary reward and invalid targets were given a high monetary reward. The results showed that the temporal cue validity effect was significantly smaller when the competitive reward structure was employed (Experiment 1), and we ruled out the possibility that the results were due to the practice effect (Experiment 2a) or a reward-promoting effect (Experiment 2b). When further strengthening the intensity of the reward from 1:10 to 1:100 (Experiment 3), we found a similar pattern of results to those in Experiment 1. These results suggest that reward information which was based on relative instead of absolute values can weaken, but not reverse, the orienting attention in time.

Different temporal dynamics of object-based attentional allocation for reward and non-reward objects.

Previous studies have confirmed that both non-reward objects (such as rectangles) and reward objects (such as banknotes) can guide the allocation of our attention; however, it is unclear whether the allocation mode of attention for reward objects is the same as for non-reward objects. This study aims to evaluate different modes of object-based attentional selection elicited by two types of objects: reward objects and non-reward objects. In our analysis, we used a two-rectangle paradigm in which two objects were presented visually. In a series of four experiments, we found a constant object-based effect with non-reward objects, such as rectangles and umbrellas, as stimuli in all of the stimulus onset asynchrony (SOA) conditions (Experiments 1 and 4), but the object-based effect disappeared only at longer SOA with reward objects such as monetary and food objects as stimuli (Experiments 2 and 3). Moreover, we found that monetary and food objects induced similar object-based effects. These results suggest that the temporal dynamics of object-based attentional allocation are different with respect to reward and non-reward objects, and different types of reward objects can guide attentional allocation in a similar way.

Adaptation of Ocular Opponency Neurons Mediates Attention-Induced Ocular Dominance Plasticity.

Previous research has shown that ocular dominance can be biased by prolonged attention to one eye. The ocular-opponency-neuron model of binocular rivalry has been proposed as a candidate account for this phenomenon. Yet direct neural evidence is still lacking. By manipulating the contrast of dichoptic testing gratings, here we measured the steady-state visually evoked potentials (SSVEPs) at the intermodulation frequencies to selectively track the activities of ocular-opponency-neurons before and after the "dichoptic-backward-movie" adaptation. One hour of adaptation caused a shift of perceptual and neural ocular dominance towards the unattended eye. More importantly, we found a decrease in the intermodulation SSVEP response after adaptation, which was significantly greater when high-contrast gratings were presented to the attended eye than when they were presented to the unattended eye. These results strongly support the view that the adaptation of ocular-opponency-neurons contributes to the ocular dominance plasticity induced by prolonged eye-based attention.

Causal role of the frontal eye field in attention-induced ocular dominance plasticity.

Previous research has found that prolonged eye-based attention can bias ocular dominance. If one eye long-termly views a regular movie meanwhile the opposite eye views a backward movie of the same episode, perceptual ocular dominance will shift towards the eye previously viewing the backward movie. Yet it remains unclear whether the role of eye-based attention in this phenomenon is causal or not. To address this issue, the present study relied on both the functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) techniques. We found robust activation of the frontal eye field (FEF) and intraparietal sulcus (IPS) when participants were watching the dichoptic movie while focusing their attention on the regular movie. Interestingly, we found a robust effect of attention-induced ocular dominance shift when the cortical function of vertex or IPS was transiently inhibited by continuous theta burst stimulation (cTBS), yet the effect was significantly attenuated to a negligible extent when cTBS was delivered to FEF. A control experiment verified that the attenuation of ocular dominance shift after inhibitory stimulation of FEF was not due to any impact of the cTBS on the binocular rivalry measurement of ocular dominance. These findings suggest that the fronto-parietal attentional network is involved in controlling eye-based attention in the 'dichoptic-backward-movie' adaptation paradigm, and in this network, FEF plays a crucial causal role in generating the attention-induced ocular dominance shift.

Negligible contribution of adaptation of ocular opponency neurons to the effect of short-term monocular deprivation.

Introduction: Modeling work on binocular rivalry has described how ocular opponency neurons represent interocular conflict. These neurons have recently been considered to mediate an ocular dominance shift to the eye that has viewed a backward movie for long during which time the other eye is presented with a regular movie. Unlike typical short-term monocular deprivation, the visual inputs are comparable across eyes in that "dichoptic-backward-movie" paradigm. Therefore, it remains unclear whether the ocular opponency neurons are also responsible for the short-term monocular deprivation effect which is prevalently explained by the homeostatic compensation theory. We designed two experiments from distinct perspectives to investigate this question. Methods: In Experiment 1, we mitigated the imbalance in the activity of opponency neurons between the two eyes during monocular deprivation by presenting video stimuli alternately. In Experiment 2, we directly evaluated the response of opponency neurons before and after monocular deprivation using SSVEP techniques. Results: Consistent with each other, both experiments failed to provide reliable evidence supporting the involvement of ocular opponency neurons in the short-term monocular deprivation effect. Discussion: Our results suggest that ocular opponency neurons may not play an essential role in the short-term monocular deprivation effect, potentially due to interference from the homeostatic plasticity mechanism.

Are you looking at me? Impact of eye contact on object-based attention.

Eye contact plays an important role in social interaction and can capture and hold attention. However, it is unclear whether and how objects that can also guide attentional allocation interact with eye contact in guiding attention. Therefore, the current study adapted a well-established two-rectangle paradigm and used faces depicting different gaze directions (direct and averted) or rectangles overlaid with eyes as stimuli. In Experiment 1, we simultaneously presented two faces (one direct gaze, one averted gaze) to participants, manipulating cue location (direct-gaze face, averted-gaze face). The results revealed a larger object-based effect when the cue appeared on the direct-gaze face compared to the averted-gaze face. In Experiment 2, inverted faces were presented, and the results mirrored those of Experiment 1. Interestingly, rectangles overlaid with eyes were presented in Experiment 3, and the results showed that the object-based effect was larger when the cue appeared on the direct-gaze rectangle compared to the averted-gaze rectangle. These findings suggest that eye contact can interact with objects in guiding attention and that this effect is not reliant on the presence of the face. Our results can support attentional prioritization theory and may provide a new approach for diagnosing social-cognitive impairments. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The modulation of object-based attentional selection by facial expressions.

Human beings can show preferentially attentional bias to different facial expressions. However, it is unclear whether the modulation of selective attention by facial expressions is based on the face itself (object-based attention) or its location (space-based attention). This study aimed to test this problem by using faces with different emotional valences in the two-rectangle paradigm across three experiments. We found that there was no significant difference in space-based effect among the positive, neutral, and negative conditions. However, the object-based effect was larger for the negative condition than for the neutral and positive ones, because of its slower reaction times for the invalid different-object trials. The results indicated that the object-based attentional selection was modulated by facial expressions, and that faces expressing negative emotions hamper the disengagement of attention from the whole object (i.e., the face), instead of the certain location. Our study can further add support to the attentional prioritisation hypothesis over attentional spreading hypothesis.

The influence of object similarity on real object-based attention: The disassociation of perceptual and semantic similarity.

Perceptual and semantic similarity have an impact on object-based attention for the geometric objects. However, no previous studies have disassociated perceptual properties from the semantic ones of real objects that combine perceptual and semantic properties. It is unclear whether the perceptual and semantic similarity of real objects jointly or independently guides attentional deployment. The aim of the present study was to explore the influence of object similarity on object-based attention by using a variant of the two-rectangle paradigm and disassociating the perceptual and semantic similarity of real objects. The results indicated that when the semantic of objects was similar, the object-based effect was larger for the perceptually dissimilar condition than for the perceptually similar condition, because of slower response to invalid different-object location in a dissimilar condition. Moreover, when the perception of objects was similar, the object-based effect was larger for the semantically dissimilar condition than for the semantically similar condition, due to slower response to invalid different-object location in a dissimilar condition. These results suggest that perceptual and semantic similarity can independently guide attentional allocation to real objects and the similarity may constrain the object-based attention in a way of grouping. The current study implies that the attentional prioritization hypothesis is more flexible and effective to explain the real object-based attention and also has some implication to advertising design.

The impact of monetary stimuli on object-based attention.

Previous research has implied that monetary reward to target location (a reward for spatial properties) can affect object-based attention, but no study has directly investigated the influence of monetary objects (a reward for object properties) on object-based attention. Thus, it is unclear whether and how monetary objects can affect object-based attention. To experimentally investigate this problem, this study adapted the well-established two-rectangle paradigm. In Experiment 1, either two 100-yuan notes or two 1-yuan notes were presented to participants. We found an object-based effect with faster responses to targets at an uncued position on the cued object compared to those at an equidistant position on the uncued object; the effect was similar in 100-yuan and 1-yuan note trials. In Experiment 2, two notes (one 100-yuan and one 1-yuan) were simultaneously presented to participants, and cue location (100-yuan, 1-yuan) was manipulated. We found a greater object-based effect when the cue appeared on the 100-yuan note than on the 1-yuan note. These results suggest that the rewarding property of objects can affect object-based attention by means of altering object salience.