Coherence and divergence in autonomic-subjective affective space

A central tenet of many theories of emotion is that emotional states are accompanied by distinct patterns of autonomic activity. However, experimental studies of coherence between subjective and autonomic responses during emotional states provide little evidence of coherence. Crucially, previous studies investigating coherence have either adopted univariate approaches or made limited use of multivariate analytic approaches by investigating subjective and autonomic responses separately. The current study addressed this question using a multivariate dimensional approach to build a common autonomic-subjective affective space incorporating subjective responses and three different autonomic signals (heart rate, skin conductance response, and pupil diameter), measured during an emotion-inducing task, in 51 participants. Results showed that autonomic and subjective responses could be adequately described in a two-dimensional affective space. The first dimension included contributions from subjective and autonomic responses, indicating coherence, while contributions to the second dimension were almost exclusively of autonomic covariance. Thus, while there was a degree of coherence between autonomic and subjective emotional responses, there was substantial structure in autonomic responses that did not covary with subjective emotional experience. This study, therefore, contributes new insights into the relationship between subjective and autonomic emotional responses, and provides a framework for future multimodal emotion research, enabling both hypothesis- and data-driven testing.

Mind over motor mapping: Driver response to changing vehicle dynamics

Improvements in vehicle safety require understanding of the neural systems that support the complex, dynamic task of real-world driving. We used functional near infrared spectroscopy (fNIRS) and pupilometry to quantify cortical and physiological responses during a realistic, simulated driving task in which vehicle dynamics were manipulated. Our results elucidate compensatory changes in driver behavior in response to changes in vehicle handling. We also describe associated neural and physiological responses under different levels of mental workload. The increased cortical activation we observed during the late phase of the experiment may indicate motor learning in prefrontal-parietal networks. Finally, relationships among cortical activation, steering control, and individual personality traits suggest that individual brain states and traits may be useful in predicting a driver's response to changes in vehicle dynamics. Results such as these will be useful for informing the design of automated safety systems that facilitate safe and supportive driver-car communication.

Affective bias as a rational response to the statistics of rewards and punishments

Affective bias, the tendency to differentially prioritise the processing of negative relative to positive events, is commonly observed in clinical and non-clinical populations. However, why such biases develop is not known. Using a computational framework, we investigated whether affective biases may reflect individuals' estimates of the information content of negative relative to positive events. During a reinforcement learning task, the information content of positive and negative outcomes was manipulated independently by varying the volatility of their occurrence. Human participants altered the learning rates used for the outcomes selectively, preferentially learning from the most informative. This behaviour was associated with activity of the central norepinephrine system, estimated using pupilometry, for loss outcomes. Humans maintain independent estimates of the information content of distinct positive and negative outcomes which may bias their processing of affective events. Normalising affective biases using computationally inspired interventions may represent a novel approach to treatment development.

CIDER: Enhancing the Performance of Computational Eyeglasses

The human eye offers a fascinating window into an individual's health, cognitive attention, and decision making, but we lack the ability to continually measure these parameters in the natural environment. We demonstrate CIDER, a system that operates in a highly optimized low-power mode under indoor settings by using a fast Search-Refine controller to track the eye, but detects when the environment switches to more challenging outdoor sunlight and switches models to operate robustly under this condition. Our design is holistic and tackles a) power consumption in digitizing pixels, estimating pupillary parameters, and illuminating the eye via near-infrared and b) error in estimating pupil center and pupil dilation. We demonstrate that CIDER can estimate pupil center with error less than two pixels (0.6°), and pupil diameter with error of one pixel (0.22mm). Our end-to-end results show that we can operate at power levels of roughly 7mW at a 4Hz eye tracking rate, or roughly 32mW at rates upwards of 250Hz.

Remission prognosis for cognitive therapy for recurrent depression using the pupil: utility and neural correlates

BACKGROUND

Although up to 60% of people with major depressive disorder respond to cognitive therapy (CT) in controlled trials, clinicians do not routinely use standardized assessments to inform which patients should receive this treatment. Inexpensive, noninvasive prognostic indicators could aid in matching patients with appropriate treatments. Pupillary response to emotional information is an excellent candidate, reflecting limbic reactivity and executive control. This study examined 1) whether pretreatment assessment of pupillary responses to negative information were associated with remission in CT and 2) their associated brain mechanisms.

METHODS

We examined whether pretreatment pupillary responses to emotional stimuli were prognostic for remission in an inception cohort of 32 unipolar depressed adults to 16 to 20 sessions of CT. Twenty patients were then assessed on the same task using functional magnetic resonance imaging. Pupillary responses were assessed in 51 never-depressed controls for reference.

RESULTS

Remission was associated with either low initial severity or the combination of higher initial severity and low sustained pupillary responses to negative words (87% correct classification of remitters and nonremitters, 93% sensitivity, 80% specificity; 88% correct classification of high-severity participants, p < .01, 90% sensitivity, 92% specificity). Increased pupillary responses were associated with increased activity in dorsolateral prefrontal regions associated with executive control and emotion regulation.

CONCLUSIONS

For patients with higher severity, disruptions of executive control mechanisms responsible for initiating emotion regulation, which are indexed by low sustained pupil responses and targeted in therapy, may be key to remitting in this intervention. These mechanisms can be measured using inexpensive noninvasive psychophysiological assessments.