Amygdala

The amygdala is a subcortical structure, which got its name because of its almond shape. Amygdalar involvement is believed to play a crucial role in emotion. Although mentioned in other entries, the present page is designed to cover topics primarily relating to this particular brain region.

Prefrontal Cortex, Amygdala & Aggression Siegel & Victoroff (2009) admonish that there exist two categories of aggression: defensive and predatory. The former activates the medial hypothalamus and midbrain periaqueductal gray (PAG), while the latter is associated with activity in the lateral hypothalamus.

Still, the prefrontal cortex (PFC), particularly the inferior frontal gyrus (IFG) and the amygdala have also been implicated in aggressive behavior. For example, previous substance abuse recovery studies have shown that metamphetamine dependent individuals show deficits in this cortical framework.

amygdala

Let's say this is cortical framework. Source of the illustration : Megan Jorgensen Album

Thus, Payer et al. (2011) wondered why persons with metamphetamine addictions were more prone to violent outburtsts. Their fMRI study of abstinent subjects with the addiction found the emotional regulation circuitry intact. However, there was lower activity in the ventral IFG, which led the researchers to conclude that aggression is precipitated through another mechanism, namely the associated alexithymia. Alexithymia refers to dysfunctional emotion processing and understanding.

They believe that it is poor emotional insight and not cognitive function per se, that is to blame for increased reported aggressive behavior in people dependent on the drug.

References:

  • Payer, D. E., Lieberman, M. D. & London, E. D. (2011). Neural correlates of affect processing and aggression in metamphetamine dependence. (Reprinted) Archives of General Psychiatry, 68 (3): 271-82.
  • Siegel, A. & Victoroff, J. (2009). Understanding human aggression: New insights from neuroscience. International Journal of Law and Psychiatry, 32: 209-15.
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