This page treats the amygdala as a bilateral nuclear complex even though the displayed Human Reference Atlas mesh is left-sided. The two amygdalae are homologous, but neither is internally uniform: basolateral, superficial, centromedial, and intercalated territories have different cell types, connections, and roles. A gross mesh cannot show those nuclear boundaries. Statements about an “amygdala response” should therefore not be read as evidence that every nucleus, or both hemispheres, contributes identically.

The familiar basolateral-to-central diagram captures an important route in associative threat learning, but it compresses meaningful nuclear differences. Sensory thalamic and cortical information enters especially through the lateral nucleus, while the basal and basolateral nuclei are more strongly interconnected with hippocampal and prefrontal systems; central and medial outputs can influence autonomic, endocrine, and defensive responses through hypothalamic and brainstem targets. Among the major amygdalar output routes, the stria terminalis follows a long arching course toward the bed nucleus and hypothalamic region, whereas the ventral amygdalofugal pathway takes a more direct ventral course toward septal, hypothalamic, basal-forebrain, and frontal targets. The real circuitry also contains parallel and recurrent pathways, intercalated inhibitory cells, and regulatory inputs from prefrontal and cingulate cortex. “Fear centre” is consequently misleading: the amygdala helps evaluate biologically relevant information within distributed circuits rather than generating a unitary emotion by itself.

The amygdala also affects attention and memory. Basolateral activity can modulate consolidation in other memory systems, helping emotionally arousing events—pleasant or unpleasant—persist. Its reciprocal relationship with the hippocampal formation links motivational relevance with context. The salience label on this page denotes a broad association with systems that prioritise relevant internal and external events; the canonical cortical salience-network hubs are anterior insula and dorsal anterior cingulate cortex, not the amygdala alone.

Human lesion evidence requires careful wording. Bilateral amygdala damage has impaired recognition of fear in facial expressions and conditioned autonomic learning in landmark cases, but results vary across people and tasks. A follow-up study found the clearest facial-fear deficit after bilateral rather than unilateral damage, contradicting a simple right-amygdala-only account. Klüver-Bucy syndrome is broader still: it is associated with bilateral temporal injury that commonly extends beyond the amygdala, and complete forms are uncommon. Visual object agnosia in a complete syndrome particularly implicates adjacent ventral occipitotemporal association cortex rather than the amygdala alone; the historical term “psychic blindness” has also been used more broadly for loss of an object’s emotional significance. The syndrome therefore cannot be attributed to an isolated amygdala lesion or reduced to one visual mechanism.

Functional imaging implicates amygdala-centred circuitry in anxiety and post-traumatic stress disorder at the group level. Meta-analyses report altered responses during emotional tasks, and treatment studies report changes in amygdala connectivity after exposure-based therapy. These associations do not make an amygdala scan diagnostic, do not show that one region causes the disorder, and should not be interpreted as a treatment biomarker for an individual patient.