Pupil Constrictions and Their Associations With Increased Negative Affect During Responses to Recalled Memories of Interpersonal Stress

Pupil diameter change is indicative of emotional processing. Most previous findings regarding pupillary response and emotion have reported that the pupil enlarges in response to the presentation of emotional perceptual stimuli (e.g., visual images) within several seconds. It is considered that such stimuli activate the sympathetic nervous system, leading to pupil dilation. In order to examine the effects of emotions similar to daily emotional experiences of mood, the present study examined pupil diameter changes and their relationships with subjective emotional changes while recalling a topic of stressful interpersonal events in daily life. The data of 20 university students (11 males, Mage = 20.36 ± 2.38 years; 9 females, Mage = 22.33 ± 3.57) were analyzed. In the experimental task, participants were instructed to recall their memories concerning the topic through instructions and questions presented on a monitor, which proceeded at their own pace, through a key press. Subsequently, after baseline and instruction periods, participants were instructed to freely recall their memories. They were then asked to respond silently to a series of questions concerning the freely recalled memories. In the analysis, we compared the pupil diameters between these different periods and observed that pupil diameters significantly decreased during the response period relative to the free recall or baseline periods. Furthermore, pupil constrictions during the response period were negatively correlated with increases in negative affect scale scores. Pupil constriction, which is indicative of decreased arousal level and parasympathetic activation, was presumably caused by multiple factors including less cognitive difficulty and a relatively long experimental task period. As the result of a less tonic mode in the response period, the attention of participants might be more successfully focused on ongoing tasks, which might lead to optimal performance in recalling memories, possibly leading to correlations between pupil diameter and negative emotional changes.

Gaze dynamics of feature-based distractor inhibition under the prior-knowledge and expectation

Prior information about distractor facilitates selective attention to task-relevant items and helps the optimization of oculomotor planning. Particularly, feature-based attentional inhibition could be benefited from the pre-knowledge of critical features of the distractors. In the present study, we capitalized on gaze-position decoding to examine the dynamics of attentional deployment in a feature-based attentional task that involved two groups of dots (target/distractor dots) moving toward different directions. Specifically, this measurement revealed how pre-knowledge of the target’s or distractor’s direction modulated real-time feature-based attentional bias. In Experiment 1, participants were provided with target cues indicating the moving direction of target dots. The results showed that participants were biased towards the cued direction and tracked the target dots throughout the task period. In Experiment 2 and Experiment 3, participants were provided with cues that informed the moving direction of distractor dots. The results showed that participants would continuously monitor the distractor’s direction when the distractor cue varied on a trial-by-trial basis (Experiment 2). However, when the to-be-ignored distractor direction remained constant (Experiment 3), participants would strategically bias their attention to the distractor’s direction before the cue onset and reduce the cost of re-deployment of attention between trials. These results suggest that monitoring the distractor’s feature is a prerequisite for feature-based attentional inhibition and this process is facilitated by the predictability of the distractor’s feature.

Iterative learning of human partner’s desired trajectory for proactive human–robot collaboration

A period-varying iterative learning control scheme is proposed for a robotic manipulator to learn a target trajectory that is planned by a human partner but unknown to the robot, which is a typical scenario in many applications. The proposed method updates the robot’s reference trajectory in an iterative manner to minimize the interaction force applied by the human. Although a repetitive human–robot collaboration task is considered, the task period is subject to uncertainty introduced by the human. To address this issue, a novel learning mechanism is proposed to achieve the control objective. Theoretical analysis is performed to prove the performance of the learning algorithm and robot controller. Selective simulations and experiments on a robotic arm are carried out to show the effectiveness of the proposed method in human–robot collaboration.

A closer look at the timecourse of mind wandering: pupillary responses and behaviour

Mind wandering (MW) refers to the shift of attention away from a primary task and/or external environment towards thoughts unrelated to the task. Recent evidence has shown that pupillometry can be used as an objective marker of the onset and maintenance of externally-driven MW episodes. In the present study we aimed to further investigate pupillary changes associated with the onset and duration of self-reported MW episodes.We used a modified version of the joint behavioural-pupillometry paradigm we recently introduced. Participants were asked to perform a monotonous vigilance task which was intermixed with task-irrelevant cue-phrases (visually presented verbal cues); they were instructed to interrupt the task whenever a thought came to mind (self-caught method) and to indicate the trigger of their thought, if any. We found systematic pupil dilation after the presentation of verbal cues reported to have triggered MW, compared with other verbal cues presented during a supposedly on-task period (i.e., the period immediately following the resuming of the task after a self-caught interruption and MW report). These results confirm that pupil diameter is sensitive to the changes associated with the onset of MW and its unfolding over time.Moreover, by computing the latency between the trigger presentation and the task interruption (self-catch), we could also estimate the duration of MW episodes triggered by verbal cues. However, a high variability was found, implying very large inter-event variability, which could not be explained by any of the MW properties we acquired (including: temporal focus, specificity, emotional valence). Our behavioural and pupillometry findings stress the need for objective measures about the temporal unfolding of MW (while most studies focus on arbitrary time-window preceding self-reports of MW).

Dynamic changes in large-scale functional connectivity predict performance in a multisensory task

Complex and variable behavior requires fast changes of functional connectivity in large-scale cortical networks. Here, we report on the cortical dynamics of functional coupling across visual, auditory and parietal areas during a lateralized detection task in the ferret. We hypothesized that fluctuations in coupling, indicative of dynamic variations in the network state, might predict the animals’ performance. While power for hit and miss trials showed significant differences only around stimulus and response onset, phase coupling already differed before stimulus onset. Principal component analysis of directed coupling at the single-trial level during this period revealed subnetworks that most strongly related to behavior. While higher global phase coupling of visual and auditory regions to parietal cortex was predictive of task performance, a second component showed that a reduction in coupling between subnetworks of sensory modalities was also necessary, probably to allow a better detection of the unimodal signals. Furthermore, we observed that long-range coupling became more predominant during the task period compared to the pre-stimulus baseline. Taken together, these results suggest that fluctuations in the network state, particular with respect to long-range connectivity, are key determinants of the animals’ behavior.

Task-Related Hemodynamic Responses Are Modulated by Reward and Task-engagement

Hemodynamic recordings from visual cortex contain powerful endogenous task-related responses that may reflect task-engagement distinct from attention. We tested this hypothesis with hemodynamic measurements (intrinsic-signal optical imaging) from monkey V1, while the animals’ engagement in a periodic fixation task over several hours was varied though reward size, and as animals took breaks. With higher rewards, animals appeared more task-engaged; task-related responses were more temporally precise at the task period (~ 10-20 seconds), and modestly stronger. Surprisingly, 2-5-minute blocks of high-reward trials led to ramp-like decreases in mean local blood volume; these reversed with ramp-like increases during low reward. The blood volume increased even more sharply when the animal shut his eyes and disengaged completely from the task (5-10 minutes). We propose a mechanism that controls vascular tone, likely along with local neural responses, with phasic and tonic components tied to task-engagement.

Montmorency Tart cherries (Prunus cerasus L.) modulate vascular function acutely, in the absence of improvement in cognitive performance

Cerebral blood volume and metabolism of oxygen decline as part of human ageing, and this has been previously shown to be related to cognitive decline. There is some evidence to suggest that polyphenol-rich foods can play an important role in delaying the onset or halting the progression of age-related health disorders such as CVD and Alzheimer’s disease and to improve cognitive function. In the present study, an acute, placebo-controlled, double-blinded, cross-over, randomised Latin-square design study with a washout period of at least 14 d was conducted on twenty-seven, middle-aged (defined as 45–60 years) volunteers. Participants received either a 60 ml dose of Montmorency tart cherry concentrate (MC), which contained 68·0 (sd 0·26) mg cyanidin-3-glucoside/l, 160·75 (sd 0·55) mean gallic acid equivalent/l and 0·59 (sd 0·02) mean Trolox equivalent/l, respectively, or a placebo. Cerebrovascular responses, cognitive performance and blood pressure were assessed at baseline and 1, 2, 3 and 5 h following consumption. There were significant differences in concentrations of total Hb and oxygenated Hb during the task period 1 h after MC consumption (P≤0·05). Furthermore, MC consumption significantly lowered systolic blood pressure (P≤0·05) over a period of 3 h, with peak reductions of 6±2 mmHg at 1 h after MC consumption relative to the placebo. Cognitive function and mood were not affected. These results show that a single dose of MC concentrate can modulate certain variables of vascular function; however, this does not translate to improvements in cognition or mood.