Amygdala Subfield Segmentation

Legend for both columns shown at bottom of page

Mai Atlas	Amygdala subfield parcellation (7T MRI)








Mai Atlas Legend AB access, basal amygdaloid nucleus, AAA anterior amygdaloid area, ACo anterior cortical amygdaloid nucleus ACoD anterior cortical amygdaloid nucleus, dorsal part ACoV anterior cortical amygdaloid nucleus, ventral part AHi amygdalohippocampal area AI amygdaloid island BL basolateral amygdaloid nuclues BLD basolateral amygdaloid nuclues, dorsal (magnocellular) part BLI basolateral amygdaloid nuclues, intermediate part BLPL basolateral amygdaloid nuclues, paralaminar part BLVL basolateral amygdaloid nucleus, ventrolateral part BLVM basolateral amygdaloid nucleus, ventromedial part BM basomedial amygdaloid nucleus BMDM basomedial amygdaloid nucleus, dorsomedial part BMVM basomedial amygdaloid nucleus, ventromedial part Ce central amygdaloid nucleus CeL central amygdaloid nucleus, lateral part CeM central amygdaloid nucleus, medial part La lateral amygdaloid nuclues LaDA lateral amygdaloid nuclues, dorsol anterior part LaDL lateral amygdaloid nuclues, dorsolateral part LaDM lateral amygdaloid nuclues, dorsomedial part LaI lateral amygdaloid nuclues, intermediate part Me medial amygdaloid nuclues MeA medial amygdaloid nuclues, anterior part PCo posterior cortical amygdaloid nuclues

In the most rostral coronal plane in which the amygdala is present, the lateral nucleus appears as a small circle of grey matter surrounded by white matter inferior to the preamygdalar claustrum, with only the lateral nucleus present.

Moving caudally, the lateral nucleus increases in area in the shape of an ellipse with the basolateral and basomedial nuclei appearing ap-proximately two millimeters caudal to the most rostral aspect of the lateral nucleus.

The basolateral and basomedial nuclei appear adjacent to and medial to the lateral nucleus, the basomedial nucleus being superior to the basolateral nucleus, with the most lateral aspect of the basolateral and basomedial nuclei are inferior to the entorhinal sulcus. The lateral nucleus continues to be bounded inferiorly and laterally by white matter.

The preamygdalar claustrum is superior to the lateral nucleus, and forms the superior and medial boundary to the basolateral and basomedial nuclei. Moving caudally the lateral nucleus decreases in area while forming the lateral extent of the amygdale, with the lateral nucleus no longer present when the hippocampus reaches its maximum width.

The centromedial nucleus increases in area and forms the superior boundary to the basomedial nucleus and the most lateral aspect of the basolateral nucleus. More caudally the centromedial nucleus forms the superior extent of the amygdala.

The basolateral nucleus has a concave shape, forming the lateral and inferior extent of the amygdala. The medial extent of the amygdala is comprised of the basolateral and basomedial nuclei, the basomedial nucleus occupying the space formed by the concavity of the basolateral nucleus.

More caudally the basolateral nucleus diminishes in area until it disappears. This occurs approximately at the coronal plane at which the semi annular sulcus can no longer be detected, with the basomedial nucleus lieing inferior to the centromedial nucleus.

Moving further caudally the basomedial nucleus gradually disappears leaving the centromedial nucleus as the only amygdala subfield. The basomedial nucleus gradually de-creases in size until it can no longer be detected. The subfields are then refined in the sagittal and axial planes.

Reference: Left column shows amygdala subdivisions from Mai, J.K., Assheuer, J., Paxinos, G. 2008. Atlas of the human brain. 3rd ed. Elsevier Academic Press, Amsterdam ; Boston.