Amygdala Analysis

The article “What is the amygdala” by Swanson and Petrovich asks whether the concept of structurally and functionally defined amygdala is truly valid or whether the concept is imposing illogical categorization on diverse structures that belongs to different functional systems. The authors discuss evidence that support latter is the case. Evidence from immunochemistry for GABA and in situ hybridization for glutamic acid decarboxylase suggest that the extrinsic projections of the central amygdalar nucleus (CEA) and medial amygdalar nucleus (MEA) are largely GABAergic, while the chief extrinsic connections of the remaining amygdala is likely glutamatergic. This supports the notion that part of the amygdala is striatal and the rest are cortical. Substantial amount of evidence shows us that most cortical projection neurons use glutamate and descending projections of striatum use GABA. This implies that non-GABA-projecting regions of the amygdala are part of the cortex. Furthermore, the CEA projects to visceral centers in the brainstem. Also, the extended cortical division of amygdala contains the cortical amygdalar nucleus (COA) - accessary olfactory bulb input as well as the rest of the COA, the nucleus of the lateral olfactory tract (NLOT), and the areas of main olfactory bulb input. Moreover, the lateral nucleus amygdala and basolateral nucleus amygdala form a ventromedial extension of the claustrum for large regions of the frontal …show more content…
Johnston introduced the fundamental description of the amygdala widely used today in 1923. However, today we have much more extensive and reliable evidence available to us that supports that the amygdala is not a structural or functional unit. Therefore, we should not arbitrary classify heterogeneous structures that belong to different functional