Amygdala

Summary

The amygdala is an almond-shaped set of neuronal nuclei located deep within the brain's medial temporal lobe, just anterior to the hippocampus (shown in Figure 1). The amygdala is an important component of the limbic system, a neural network that mediates many aspects of emotional learning and behavior and plays a prominent role in processing of certain emotions, including fear. Abnormal functioning or damage within the amygdala, and the neural circuits that connect it with a variety of cortical and subcortical structures, is thought to contribute to the pathophysiology of a number of neuropsychiatric disorders, such as anxiety, autism and depression.

The transcriptome analysis shows that 73% (n=14599) of all human protein-coding genes (n=20090) are expressed in the human amygdala. Human one-to-one orthologues were investigated in pig and mouse brain, suggesting that 12166 of all mouse one-to-one orthologues (n=16320) are expressed in the mouse amygdala and that 13015 of all pig orthologues (n=15829) are expressed in the pig amygdala.

Gene classification based on regional RNA expression in human, pig and mouse amygdala defines 0 genes as amygdala enriched in either of the three species.

Figure 1. Schematic drawing of the human brain, indicating the location of amygdala from a coronal perspective.

Anatomical divisions

The basolateral complex is the largest of the amygdaloid clusters, located roughly within the lateral and middle parts of the amygdala, and includes the lateral and basal nuclei, while the cortical and medial nuclei comprise the cortico-medial amygdaloid group. Interestingly, the basolateral amygdala has been implicated in both mediating the formation of memories related to emotional events and fear extinction (learning process resulting in the elimination of a previously elicited fear response) through interaction with the prefrontal cortex.


SH3GL2

SLC18A3

CCK

Regionally elevated protein expression in human

Table 1: Number of genes within the different categories of regionally elevated expression, in human amygdala

Specificity Number of Human elevated genes
Region enriched 0
Group enriched 10
Region enhanced 1
Elevated 11

The transcriptome analysis shows that 73% (n=14599) of all human proteins (n=20090) are expressed in the amygdala and 11 genes show an elevated expression level in amygdala compared to other regions of the brain.

  • 0 regionally enriched genes
  • 11 regionally elevated genes in total
  • 4 of the amygdala elevated genes are elevated in other tissues than the brain.
  • 7 of the amygdala elevated genes are elevated in the brain.

Elevated expression in amygdala compared to other brain regions is divided into three different categories; regionally enriched (at least four-fold higher mRNA levels in amygdala compared to all other regions), group enriched (at least four-fold higher mRNA levels in a group of 2-5 regions) and regionally enhanced (at least four-fold higher mRNA levels in amygdala compared to the average of all regions), The number of genes in the individual category is shown in Table 1.

Regionally elevated protein expression in mouse


The transcriptome analysis shows that 61% (n=12166) of all mouse one-to-one human orthologue genes (n=16320) are expressed in the amygdala. 38 genes show an elevated expression in amygdala compared to other regions of the brain.

Table 2: Number of genes within the different categories of regionally elevated expression, in amygdala

Specificity Number of Mouse elevated genes
Region enriched 0
Group enriched 36
Region enhanced 2
Elevated 38

Figure 2. Schematic drawing of the mouse brain, indicating the location of amygdala from a coronal perspective.

Regionally elevated protein expression in pig



The transcriptome analysis shows that 65% (n=13015) of all pig one-to-one human orthologue genes (n=15829) are expressed in the amygdala. 41 genes show an elevated expression in amygdala compared to other regions of the brain.


Table 3: Number of genes within the different categories of regionally elevated expression, in amygdala

Specificity Number of Pig elevated genes
Region enriched 0
Group enriched 40
Region enhanced 1
Elevated 41

Figure 3. Schematic drawing of the pig brain, indicating the location of amygdala from a coronal perspective or sagittal view.

Extended information

No extended information for the Amygdala