Lying in a 3T MRI scanner induces neglect-like spatial attention bias

The static magnetic field of MRI scanners can induce a magneto-hydrodynamic stimulation of the vestibular organ (MVS). In common fMRI settings, this MVS effect leads to a vestibular ocular reflex (VOR). We asked whether – beyond inducing a VOR – putting a healthy subject in a 3T MRI scanner would also alter goal-directed spatial behavior, as is known from other types of vestibular stimulation. We investigated 17 healthy volunteers, all of which exhibited a rightward VOR inside the MRI-scanner as compared to outside-MRI conditions. More importantly, when probing the distribution of overt spatial attention inside the MRI using a visual search task, subjects scanned a region of space that was significantly shifted toward the right. An additional estimate of subjective straight-ahead orientation likewise exhibited a rightward shift. Hence, putting subjects in a 3T MRI-scanner elicits MVS-induced horizontal biases of spatial orienting and exploration, which closely mimic that of stroke patients with spatial neglect.

Neural Correlates of Value-Driven Spatial Attention

Reward learning has been shown to habitually guide spatial attention to regions of a scene. However, the neural mechanisms that support this bias in spatial orienting are unknown. In the present study, participants learned to orient to a particular quadrant of a scene (high-value quadrant) to maximize monetary gains. This learning was scene-specific, with the high-value quadrant varying across different scenes. During a subsequent test phase, participants were faster at identifying a target if it appeared in the high-value quadrant (valid), and initial saccades were more likely to be made to the high-value quadrant. fMRI analyses during the test phase revealed learning-dependent priority signals in the bilateral caudate tail and superior colliculus, frontal eye field, substantia nigra, and insula, paralleling findings concerning feature-based value-driven attention. In addition, ventral regions typically associated with scene selective and spatial information processing, including the hippocampus, parahippocampal gyrus, and temporo-occipital cortex, were also implicated. Taken together, our findings offer new insights into the neural architecture subserving value-driven attention, both extending our understanding of nodes in the attention network previously implicated in feature-based value-driven attention and identifying a ventral network of brain regions implicated in rewards influence on scene-dependent spatial orienting.

Athletics and attention: Bi-directional influences in the lab and on the field

Selectively attending to some information while ignoring other information is crucial for athletic success. Active participation in athletics is also beneficial when attention is measured in the laboratory. This review examines this bi-directional relationship between athletics and attention. The introduction orients readers to the concept of selective visual attention. In the following section we review the evidence that athletic participation influences performance on laboratory measures of visual attention, including tasks of spatial orienting, spatial shifting, attention distribution, temporal sequencing, and the control of action. In the third section we review how attention measures are influenced by contextual factors that are also known to influence athletic performance. These include behavioral practices like exercise, sleep, and hydration; environmental factors like thermal stress, competition, and distraction; and individual differences in personality, age, and gender. In the next section we situate all this empirical evidence in the evolving theoretical understanding of attention in the cognitive sciences over the past five decades. In doing so, it becomes clear that research on athletics is an important database to consider when developing models of attention. By bringing these literatures together, a stronger theoretical foundation is sought that may contribute positively to research on both optimal athletic performance and framework development in attention.

Methylphenidate reduces orienting bias in healthy individuals

Background: Healthy individuals show subtle orienting bias, a phenomenon known as pseudoneglect, reflected in a tendency to direct greater attention toward one hemispace. Accumulating evidence indicates that this bias is an individual trait, and attention is preferentially directed contralaterally to the hemisphere with higher dopamine signaling. Administration of methylphenidate (MPH), a dopamine transporter inhibitor, was shown to normalize aberrant spatial attention bias in psychiatric and neurological patients, suggesting that the reduced orienting bias following administration of MPH reflects an asymmetric effect of the drug, increasing extracellular dopamine in the hemisphere with lower dopamine signaling. Aim: We predicted that, similarly to its effect on patients with brain pathology, MPH will reduce the orienting bias in healthy subjects. Methods: To test this hypothesis, we examined the behavioral effects of a single dose (20 mg) of MPH on orienting bias in 36 healthy subjects (18 females) in a randomized, double-blind placebo-controlled, within-subject design, using the greyscales task, which has been shown to detect subtle attentional biases in both patients and healthy individuals. Results/outcomes: Results demonstrate that healthy individuals vary in both direction and magnitude of spatial orienting bias and show reduced magnitude of orienting bias following MPH administration, regardless of the initial direction of asymmetry. Conclusions/interpretations: Our findings reveal, for the first time in healthy subjects, that MPH decreases spatial orienting bias in an asymmetric manner. Given the well-documented association between orienting bias and asymmetric dopamine signaling, these findings also suggest that MPH might exert a possible asymmetric neural effect in the healthy brain.

Dissociating breathlessness symptoms from mood in asthma

Asthma is one of many chronic diseases in which discordance between objectively measured pathophysiology and symptom burden is well recognised. Understanding the influences on symptom burden beyond pathophysiology could improve our ability to treat symptoms. While co-morbidities such as anxiety and depression may play a role, the impact of this relationship with symptoms on our ability to perceive bodily sensations (termed ‘interoception’), or even our general and symptom-specific attention is not yet understood. Here we studied 63 individuals with asthma and 30 healthy controls. Alongside physiological tests including spirometry, bronchodilator responsiveness, expired nitric oxide and blood eosinophils, we collected self-reported questionnaires covering affective factors such as anxiety and depression, as well as asthma symptoms and asthma-related quality of life (individuals with asthma only). Participants additionally completed a breathing-related interoception task and two attention tasks designed to measure responsiveness to general temporal/spatial cues and specific asthma-related threatening words. We conducted an exploratory factor analysis across the questionnaires which gave rise to key components of ‘Mood’ and ‘Symptoms’, and compared these to physiological, interoceptive and attention measures. While no relationships were found between symptoms and physiological measures in asthma alone, negative mood was related to both decreased interoceptive metacognitive sensitivity (‘insight’ into interoceptive performance) and metacognitive bias (confidence in interoceptive decisions), as well as increased effects of spatial orienting cues in both asthma and controls. Furthermore, the relationship between the extent of symptoms and negative mood revealed potential sub-groups within asthma, with those who displayed the most severe symptoms without concurrent negative mood also demonstrating altered physiological, interoceptive and attention measures. Our findings are a step towards understanding how both symptoms and mood are related to our ability to interpret bodily symptoms, and to explore how the balance between mood and symptoms may help us understand the heterogeneity in conditions such as asthma.

Microsaccadic Eye Movements but not Pupillary Dilation Response Characterizes the Crossmodal Freezing Effect

In typical spatial orienting tasks, the perception of crossmodal (e.g., audiovisual) stimuli evokes greater pupil dilation and microsaccade inhibition than unisensory stimuli (e.g., visual). The characteristic pupil dilation and microsaccade inhibition has been observed in response to “salient” events/stimuli. Although the “saliency” account is appealing in the spatial domain, whether this occurs in the temporal context remains largely unknown. Here, in a brief temporal scale (within 1 s) and with the working mechanism of involuntary temporal attention, we investigated how eye metric characteristics reflect the temporal dynamics of perceptual organization, with and without multisensory integration. We adopted the crossmodal freezing paradigm using the classical Ternus apparent motion. Results showed that synchronous beeps biased the perceptual report for group motion and triggered the prolonged sound-induced oculomotor inhibition (OMI), whereas the sound-induced OMI was not obvious in a crossmodal task-free scenario (visual localization without audiovisual integration). A general pupil dilation response was observed in the presence of sounds in both visual Ternus motion categorization and visual localization tasks. This study provides the first empirical account of crossmodal integration by capturing microsaccades within a brief temporal scale; OMI but not pupillary dilation response characterizes task-specific audiovisual integration (shown by the crossmodal freezing effect).

Robot Faces that Follow Gaze Facilitate Attentional Engagement and Increase Their Likeability

Gaze behavior of humanoid robots is an efficient mechanism for cueing our spatial orienting, but less is known about the cognitive-affective consequences of robots responding to human directional cues. Here, we examined how the extent to which a humanoid robot (iCub) avatar directed its gaze to the same objects as our participants affected engagement with the robot, subsequent gaze cueing and subjective ratings of the robot’s characteristic traits. In a gaze-contingent eyetracking task, participants were asked to indicate a preference for one of two objects with their gaze whilst an iCub avatar was presented between the object photographs. In one condition, the iCub then shifted its gaze toward the object chosen by a participant in 80% of the trials (joint condition) and in the other condition it looked at the opposite object 80% of the time (disjoint condition). Based on the literature in human-human social cognition, we took the speed with which the participants looked back at the robot as a measure of facilitated reorienting and robot-preference, and found these return saccade onset times to be quicker in the joint condition than in the disjoint condition. As indicated by results from a subsequent gaze-cueing tasks, the gaze-following behavior of the robot had little effect on how our participants responded to gaze cues. Nevertheless, subjective reports suggested that our participants preferred the iCub following participants’ gaze to the one with a disjoint attention behavior, rated it as more human-like and as more likeable. Taken together, our findings show a preference for robots who follow our gaze. Importantly, such subtle differences in gaze behavior are sufficient to influence our perception of humanoid agents, which clearly provides hints about the design of behavioral characteristics of humanoid robots in more naturalistic settings.