Suchergebnisse

AbstractHumans learn about their environments by observing others, including what to fear and what to trust. Observational fear learning may be especially important early in life when children turn to their parents to gather information about their world. Yet, the vast majority of empirical research on fear learning in youth has thus far focused on firsthand classical conditioning, which may fail to capture one of the primary means by which fears are acquired during development. To address this gap in the literature, the present study examined observational fear learning in youth (n = 33; age range: 6–17 years) as they watched videos of their parent and an "unfamiliar parent" (i.e., another participant's parent) undergo fear conditioning. Youth demonstrated stronger fear learning when observing their parent compared to an unfamiliar parent, as indicated by changes in their self‐reported liking of the stimuli to which their parents were conditioned (CS+, a geometric shape paired with an aversive noise; CS‐, a geometric shape never paired with an aversive noise) and amygdala responses. Parent trait anxiety was associated with youth learning better (i.e., reporting a stronger preference for the CS‐ relative to CS+), and exhibiting stronger medial prefrontal‐amygdala connectivity. Neuroimaging data were additionally acquired from a subset of parents during firsthand conditioning, and parental amygdala and mPFC activation were associated with youth's neural recruitment. Together, these results suggest that youth preferentially learn fears via observation of their parents, and this learning is associated with emotional traits and neural recruitment in parents.

AbstractLearning safe versus dangerous cues is crucial for survival. During development, parents can influence fear learning by buffering their children's stress response and increasing exploration of potentially aversive stimuli. Rodent findings suggest that these behavioral effects are mediated through parental presence modulation of the amygdala and medial prefrontal cortex (mPFC). Here, we investigated whether similar parental modulation of amygdala and mPFC during fear learning occurs in humans. Using a within‐subjects design, behavioral (final N = 48, 6–17 years, mean = 11.61, SD = 2.84, 60% females/40% males) and neuroimaging data (final N = 39, 6–17 years, mean = 12.03, SD = 2.98, 59% females/41% males) were acquired during a classical fear conditioning task, which included a CS+ followed by an aversive noise (US; 75% reinforcement rate) and a CS−. Conditioning occurred once in physical contact with the participant's parent and once alone (order counterbalanced). Region of interest analyses examined the unconditioned stress response by BOLD activation to the US (vs. implicit baseline) and learning by activation to the CS+ (vs. CS−). Results showed that during US presentation, parental presence reduced the centromedial amygdala activity, suggesting buffering of the unconditioned stress response. In response to learned stimuli, parental presence reduced mPFC activity to the CS+ (relative to the CS−), although this result did not survive multiple comparisons' correction. These preliminary findings indicate that parents modulate amygdala and mPFC activity during exposure to unconditioned and conditioned fear stimuli, potentially providing insight into the neural mechanisms by which parents act as a social buffer during fear learning.Research Highlights
This study used a within‐participant experimental design to investigate how parental presence (vs. absence) affects youth's neural responses in a classical fear conditioning task.
Parental presence reduced the youth's centromedial amygdala activation to the unconditioned stimulus (US), suggesting parental buffering of the neural unconditioned response (UR).
Parental presence reduced the youth's mPFC activation to a conditioned threat cue (CS+) compared to a safety cue (CS−), suggesting possible parental modulation of fear learning.

Abstract
The ability to learn about threat and safety is critical for survival. Studies in rodent models have shown that the gut microbiota can modulate such behaviors. In humans, evidence showing an association with threat or extinction learning is lacking. Here, we tested whether individual variability in threat and extinction learning was related to gut microbiota composition in healthy adults. We found that threat, but not extinction learning, varies with individuals' microbiome composition. Our results provide evidence that the gut microbiota is associated with excitatory threat learning across species.