Amygdalar unit activity during three learning tasks: Eyeblink classical conditioning, Pavlovian fear conditioning, and signaled avoidance conditioning

Neural activity in central and basolateral amygdala nuclei (CeA and BLA, respectively) was recorded during delay eyeblink conditioning, Pavlovian fear conditioning, and signaled barpress avoidance. During paired training, the CeA exhibited robust learning-related excitatory activity during all 3 tasks. By contrast, the BLA exhibited minimal activity during eyeblink conditioning, while demonstrating pronounced increases in learning-related excitatory responsiveness during fear conditioning and barpress avoidance. In addition, the relative amount of amygdalar activation observed appeared to be related to the relative intensity of the unconditioned stimulus and somatic requirements of the task. Results suggest the CeA mediates the Pavlovian association between sensory stimuli and the BLA mediates the modulation of instrumental responding through the assignment of motivational value to the unconditioned stimulus.