A Review Of The Nature Of The Amygdala Formation And An Examination Of The Basolateral Amygdala (BLA)

The amygdala (/əˈmɪɡdələ/; pl.: amygdalae /əˈmɪɡdəli, -laɪ/ or amygdalas; also corpus amygdaloideum; Latin from Greek, ἀμυγδαλή, amygdalē, 'almond', 'tonsil') is a paired nuclear complex present in the cerebral hemispheres of vertebrates. It is considered part of the limbic system. In primates, it is located medially within the temporal lobes. It consists of many nuclei, each made up of further subnuclei. The subdivision most commonly made is into the basolateral, central, cortical, and medial nuclei together with the intercalated cell clusters. The amygdala has a primary role in the processing of memory, decision-making, and emotional responses (including fear, anxiety, and aggression). The amygdala was first identified and named by Karl Friedrich Burdach in ۱۸۲۲. Over a dozen nuclei have been identified, each with their own subdivisions and distinct connections to the rest of the brain. The chief nuclei are the basolateral complex, the central nucleus, the cortical nucleus, the medial nucleus, and the intercalated cell clusters. The basolateral complex can be further subdivided into the lateral, the basal, and the accessory basal nuclei. It has extensive connections with higher-order cortical areas in the prefrontal, temporal, insular cortices, and the hippocampus. The basolateral complex is surrounded the intercalated cell net that is inhibitory and projects to a broad variety of areas in the basal forebrain, hypothalamus, and the amygdala. The basolateral amygdala, or basolateral complex, consists of the lateral, basal and accessory-basal nuclei of the amygdala. The lateral nuclei receives the majority of sensory information, which arrives directly from the temporal lobe structures, including the hippocampus and primary auditory cortex. The basolateral amygdala also receives dense neuromodulatory inputs from ventral tegmental area (VTA), locus coeruleus (LC), and basal forebrain, whose integrity are important for associative learning. The information is then processed by the basolateral complex and is sent as output to the central nucleus of the amygdala. This is how most emotional arousal is formed in mammals. The amygdala has several different nuclei and internal pathways; the basolateral complex (or basolateral amygdala), the central nucleus, and the cortical nucleus are the most well-known. Each of these has a unique function and purpose within the amygdala. In this study, we investigate and review the nature of the amygdala formation and examine the basolateral amygdala (BLA).

Keywords:

Amygdala Formation , Basolateral Amygdala , BLA , Ventral Tegmental Area , VTA