Processing of temporal unpredictability in human and animal amygdala

Area of Science:

• Neuroscience
• Behavioral Science
• Psychology

Background:

• The amygdala is crucial for fear conditioning.
• Noxious stimuli are most effective when unpredictable.
• Previous research linked amygdala activation to fear.

Purpose of the Study:

• To investigate if unpredictability alone, without fear, affects amygdala activity and behavior.
• To explore the role of temporal unpredictability in neural and behavioral responses.
• To examine conserved mechanisms across species.

Main Methods:

• Translational study using mice and humans.
• Mice exposed to temporally unpredictable auditory stimuli.
• Neural activity measured via c-fos expression and single-neuron recordings.
• Human functional magnetic resonance imaging (fMRI).
• Behavioral assessments including avoidance and attention to emotional faces.

Main Results:

• Temporal unpredictability increased c-fos expression and prevented habituation in the mouse amygdala.
• Unpredictable auditory stimulation induced anxiety-like and avoidance behaviors in mice.
• Human fMRI showed sustained amygdala activity and anxiety-like behavior (enhanced attention to emotional faces) due to temporal unpredictability.
• Unpredictability per se, independent of motivational context, impacted amygdala function.

Conclusions:

• Unpredictability is a significant environmental factor influencing amygdala habituation and emotional behavior.
• The amygdala's response to unpredictability is an evolutionarily conserved mechanism.
• This mechanism aids in adapting behavior to anticipate uncertain events.