Ventromedial Prefrontal Cortex Activity and Sympathetic Allostasis During Value-Based Ambivalence

Abstract

Anxiety is characterized by low confidence in daily decisions, coupled with high levels of phenomenological stress. Ventromedial prefrontal cortex (vmPFC) plays an integral role in maladaptive anxious behaviors via decreased sensitivity to threatening vs. non-threatening stimuli (fear generalization). vmPFC is also a key node in approach-avoidance decision making requiring two-dimensional integration of rewards and costs. More recently, vmPFC has been implicated as a key cortical input to the sympathetic branch of the autonomic nervous system. However, little is known about the role of this brain region in mediating rapid stress responses elicited by changes in confidence during decision making. We used an approach-avoidance task to examine the relationship between sympathetically mediated cardiac stress responses, vmPFC activity and choice behavior over long and short time-scales. To do this, we collected concurrent fMRI, EKG and impedance cardiography recordings of sympathetic drive while participants made approach-avoidance decisions about monetary rewards paired with painful electric shock stimuli. We observe first that increased sympathetic drive (shorter pre-ejection period) in states lasting minutes are associated with choices involving reduced decision ambivalence. Thus, on this slow time scale, sympathetic drive serves as a proxy for “mobilization” whereby participants are more likely to show consistent value-action mapping. In parallel, imaging analyses reveal that on shorter time scales (estimated with a trial-to-trial GLM), increased vmPFC activity, particularly during low-ambivalence decisions, is associated with decreased sympathetic state. Our findings support a role of sympathetic drive in resolving decision ambivalence across long time horizons and suggest a potential role of vmPFC in modulating this response on a moment-to-moment basis.

Thalamic regulation of frontal interactions in human cognitive flexibility

“…For example, the dorsolateral region is linked to executing cognitive functions [ 6 ], while the orbitofrontal cortex (OFC) is associated with adaptive and flexible responding in a changing environment [ 7 ]. The ventromedial region is associated with estimating the value and salience of sensory and cognitive variables and thereby, guides value-based decision-making [ 8 ].…”

Cardiac-sympathetic contractility and neural alpha-band power: cross-modal collaboration during approach-avoidance conflict

“…We using a graded extension of the approach-avoidance framework previously employed in nonhuman primate 73,74 and human 4,9–10 contexts. Participants approach or avoid varying levels of monetary reward paired with varying levels of painful electric shock, in trial-by-trial “take-both- or-leave-both” offers.…”

“…For safety reasons, we did not administer any electric shocks during the testing session while participants wore physiology electrodes. We instead postponed payout on an infrequent subset of trials, in line with previous work recording physiology signals during similar approach-avoidance paradigms 4,9 . Prior to testing, we selected eighteen “payout trials” (5.11%) with uniform probability across the entire set of offers provided the offered shock was below 80% of a subject’s maximum pain level.…”

Non-invasive monitoring of cardiac contractility and sympathetic drive: Trans-Radial Electrical Bioimpedance Velocimetry (TREV)

“…MEAP outputs were then transferred to MATLAB, where the maximum amplitude in each contractility epoch was computed as an estimation of each heartbeat's contractility (beat-wise contractility timeseries). Then, separately for each subject, and each block, we conducted an additional regression procedure (Dundon, et al, 2020;Dundon, Shapiro, Babenko, Okafor, & Grafton, 2021) to remove the additional confounding effects of heart-rate and respiration from the beat-wise contractility timeseries. Using a multiple regression model, we regressed the vector beat-wise contractility as a function of an intercept and three regressors: (i) the phase of respiration at each heartbeat, (ii) the amplitude of respiration at each heartbeat and (iii) the heartrate at each heartbeat.…”