Divergence between thalamic and cortical inputs to lateral amygdala during juvenile-adult transition in mice

Adolescence is considered a critical time of life for emotional development in humans. During this period the amygdala, which regulates emotions, undergoes structural reorganization. Auditory fear conditioning, a form of amygdala-dependent emotional learning, occurs differently in juvenile and adult rodents. Because this learning is mediated by plastic changes in the thalamic and cortical inputs to lateral amygdala (LA), we investigated changes in synaptic properties of these inputs during juvenile-to-adult transition.

Whole-cell patch clamp recording in amygdala slices from juvenile and young adult mice was conducted to investigate long-term potentiation and basal synaptic transmission in the thalamic and cortical inputs to LA.

We show that physiological differences develop between thalamic and cortical afferents to LA during the juvenile-to-adult transition. Although in juvenile mice the two pathways have similar properties, in young adult mice the thalamic pathway has reduced plasticity, increased number of quanta released by a single action potential, and decreased proportion of silent synapses.

Changes in thalamic but not cortical inputs to amygdala take place during late development and might contribute to differences in auditory fear conditioning between juveniles and adults.