Subjecting Elite Athletes to Inspiratory Breathing Load Reveals Behavioral and Neural Signatures of Optimal Performers in Extreme Environments

Background: It is unclear whether and how elite athletes process physiological or psychological challenges differently than healthy comparison subjects. In general, individuals optimize exercise level as it relates to differences between expected and experienced exertion, which can be conceptualized as a body prediction error. The process of computing a body prediction error involves the insular cortex, which is important for interoception, i.e. the sense of the physiological condition of the body. Thus, optimal performance may be related to efficient minimization of the body prediction error. We examined the hypothesis that elite athletes, compared to control subjects, show attenuated insular cortex activation during an aversive interoceptive challenge. Methodology/Principal Findings: Elite adventure racers (n = 10) and healthy volunteers (n = 11) performed a continuous performance task with varying degrees of a non-hypercapnic breathing load while undergoing functional magnetic resonance imaging. The results indicate that (1) non-hypercapnic inspiratory breathing load is an aversive experience associated with a profound activation of a distributed set of brain areas including bilateral insula, dorsolateral prefrontal cortex and anterior cingulated; (2) adventure racers relative to comparison subjects show greater accuracy on the continuous performance task during the aversive interoceptive condition; and (3) adventure racers show an attenuated right insula cortex response during and following the aversive interoceptive condition of non-hypercapnic inspirator

Brain volumetric deficits in MAPT mutation carriers: a multisite study

Objective: MAPT mutations typically cause behavioral variant frontotemporal dementia with or without parkinsonism. Previous studies have shown that symptomatic MAPT mutation carriers have frontotemporal atrophy, yet studies have shown mixed results as to whether presymptomatic carriers have low gray matter volumes. To elucidate whether presymptomatic carriers have lower structural brain volumes within regions atrophied during the symptomatic phase, we studied a large cohort of MAPT mutation carriers using a voxelwise approach. Methods: We studied 22 symptomatic carriers (age 54.7 ± 9.1, 13 female) and 43 presymptomatic carriers (age 39.2 ± 10.4, 21 female). Symptomatic carriers’ clinical syndromes included: behavioral variant frontotemporal dementia (18), an amnestic dementia syndrome (2), Parkinson’s disease (1), and mild cognitive impairment (1). We performed voxel-based morphometry on T1 images and assessed brain volumetrics by clinical subgroup, age, and mutation subtype. Results: Symptomatic carriers showed gray matter atrophy in bilateral frontotemporal cortex, insula, and striatum, and white matter atrophy in bilateral corpus callosum and uncinate fasciculus. Approximately 20% of presymptomatic carriers had low gray matter volumes in bilateral hippocampus, amygdala, and lateral temporal cortex. Within these regions, low gray matter volume

A computational modeling approach to understanding the psychological and neural mechanisms underlying directional reasoning about ambiguous events

People often view the ambiguities of their social world through a subjective, rather than objective lens. For example, people may construe ambiguous social events in ways that are consistent with their current moods or with the goals they wish to achieve (e.g., Blanchette & Richards, 2010; Pauker, Rule, & Ambady, 2010). Although both mood and motivation direct reasoning about ambiguity, little is known about whether similar mechanisms account for the effects of mood or motivation. Furthermore, similar neural profiles have been associated with mood-congruent ambiguity resolution and motivated reasoning (e.g., Bhanji & Beer, 2012; Hughes & Beer, 2013), but the extent to which these regions support the same underlying processes has not been explored. A deep understanding of the underlying mechanisms has been difficult to assess because previous research has utilized self-report and reaction time measures to explore the effects of mood and motivation on ambiguity (e.g., Butler & Mathews, 1983; Ditto et al., 1998). People have little introspective access to the cognitive processes that lead to their decisions (Nisbett & Wilson, 1977), and reaction time analyses cannot disentangle underlying mechanisms. Therefore a deeper understanding requires alternative approaches. Drift-diffusion modeling (DDM) makes it possible to independently estimate parameters related to two mechanisms theorized to be involved ambiguity construal: expectations and preferential evidence accumulation. This dissertation describes five studies that utilize DDM to examine two overarching research questions: (I) What role do expectations and preferential evidence accumulation play in the influence of mood and motivation on the construal of ambiguity (Studies 1a, 1b, 3, 4) and (II) Are these processes supported by neural regions known to be involved in the effects of mood and motivation on the construal of ambiguity (Studies 2, 4)? The findings support a predicted role for expectations in mood-congruent and motivated construals of ambiguity. In addition, VMPFC supported motivated expectations that contribute to ambiguity construal. The role of preferential evidence accumulation, on the other hand, was less robust. Findings contribute to our understanding of mood-congruent and motivated reasoning about ambiguity and suggest fruitful approaches for future work exploring directed reasoning about ambiguous events.Psycholog

Neural basis of egalitarian behavior

Individuals are willing to sacrifice their own resources to promote equality in groups. These costly choices promote equality and are associated with behavior that supports cooperation in humans, but little is known about the brain processes involved. We use functional MRI to study egalitarian preferences based on behavior observed in the “random income game.” In this game, subjects decide whether to pay a cost to alter group members’ randomly allocated incomes.Wespecifically examinewhether egalitarian behavior is associated with neural activity in the ventromedial prefrontal cortex and the insular cortex, two regions that have been shown to be related to social preferences. Consistent with previous studies, we find significant activation in both regions; however, only the insular cortex activations are significantly associated with measures of revealed and expressed egalitarian preferences elicited outside the scanner. These results are consistentwith the notion that brainmechanisms involved in experiencing the emotional states of others underlie egalitarian behavior in humans. Includes supporting information

Attenuated Neural Processing of Risk in Young Adults at Risk for Stimulant Dependence

<div><p>Objective</p><p>Approximately 10% of young adults report non-medical use of stimulants (cocaine, amphetamine, methylphenidate), which puts them at risk for the development of dependence. This fMRI study investigates whether subjects at early stages of stimulant use show altered decision making processing.</p><p>Methods</p><p>158 occasional stimulants users (OSU) and 50 comparison subjects (CS) performed a “risky gains” decision making task during which they could select safe options (cash in 20 cents) or gamble them for double or nothing in two consecutive gambles (win or lose 40 or 80 cents, “risky decisions”). The primary analysis focused on risky versus safe decisions. Three secondary analyses were conducted: First, a robust regression examined the effect of lifetime exposure to stimulants and marijuana; second, subgroups of OSU with >1000 (n = 42), or <50 lifetime marijuana uses (n = 32), were compared to CS with <50 lifetime uses (n = 46) to examine potential marijuana effects; third, brain activation associated with behavioral adjustment following monetary losses was probed.</p><p>Results</p><p>There were no behavioral differences between groups. OSU showed attenuated activation across risky and safe decisions in prefrontal cortex, insula, and dorsal striatum, exhibited lower anterior cingulate cortex (ACC) and dorsal striatum activation for risky decisions and greater inferior frontal gyrus activation for safe decisions. Those OSU with relatively more stimulant use showed greater dorsal ACC and posterior insula attenuation. In comparison, greater lifetime marijuana use was associated with less neural differentiation between risky and safe decisions. OSU who chose more safe responses after losses exhibited similarities with CS relative to those preferring risky options.</p><p>Discussion</p><p>Individuals at risk for the development of stimulant use disorders presented less differentiated neural processing of risky and safe options. Specifically, OSU show attenuated brain response in regions critical for performance monitoring, reward processing and interoceptive awareness. Marijuana had additive effects by diminishing neural risk differentiation.</p></div

Sample characteristics by group status.

<p>Abbreviations: OSU, occasional stimulant users; CS, stimulant naïve comparison subjects; THC, marijuana; Prescription Stimulants = Adderall, Ritalin (used without prescription); BIS, Barrett impulsiveness scale; SSS, sensation seeking scale, BDI, Beck depression inventory; ADHD, attention deficit hyperactivity disorder.</p><p>^a Verbal IQ estimated via WTAR or NAART.</p><p>^b Maximum number of ADHD symptoms = 21 (n = 10 attention deficit symptoms, n = 11 hyperactivity symptoms).</p><p>^c ADHD (age 6–13) and conduct (<18 years) symptoms as assessed during in-person clinical interview (SSAGA).</p><p>^d refers to t-test between Low and High THC OSU.</p><p>* Significance level of p<0.05.</p><p>Sample characteristics by group status.</p