Abnormal structure or function of the amygdala is a common component of neurodevelopmental disorders

Abstract

The amygdala, perhaps more than any other brain region, has been implicated in numerous neuropsychiatric and neurodevelopmental disorders. It is part of a system initially evolved to detect dangers in the environment and modulate subsequent responses, which can profoundly influence human behavior. If its threshold is set too low, normally benign aspects of the environment are perceived as dangers, interactions are limited, and anxiety may arise. If set too high, risk taking increases and inappropriate sociality may occur. Given that many neurodevelopmental disorders involve too little or too much anxiety or too little of too much social interaction, it is not surprising that the amygdala has been implicated in many of them. In this chapter, we begin by providing a brief overview of the phylogeny, ontogeny, and function of the amygdala and then appraise data from neurodevelopmental disorders which suggest amygdala dysregulation. We focus on neurodevelopmental disorders where there is evidence of amygdala dysregulation from postmortem studies, structural MRI analyses or functional MRI. However, the results are often disparate and it is not totally clear whether this is due to inherent heterogeneity or differences in methodology. Nonetheless, the amygdala is a common site for neuropathology in neurodevelopmental disorders and is therefore a potential target for therapeutics to alleviate associated symptoms.

Amygdala habituation: A reliable fMRI phenotype

“…Amygdala function is of high interest for cognitive, social and psychiatric neuroscience, emphasizing the need for reliable assessments in humans (Adolphs, 2010;Sander et al, 2003;Schaefer and Gray, 2007;Schumann et al, 2011). In a previous study we have compared the retest reliability of three different tasks (emotional, motivational and cognitive) comprising an fMRI task battery (Plichta et al, 2012).…”

Abolition of lifelong specific phobia: a novel therapeutic consequence of left mesial temporal lobectomy

“…The amygdala is a phylogenetically conserved structure, in evolutionary terms predating the neocortex, and consists of a number of nuclei (Schumann et al, 2011;Stephan & Andy, 1982). In humans, these nuclei may be placed into two main groups according to anatomy and neuronal substrate contained: centromedial and corticobasolateral (Stephan & Andy, 1982).…”

“…Moreover, postoperative imaging demonstrates the surgical lesion to be the widest at its medial edge, tapering as it extends. This suggests potentially greatest impact on medially located nuclei (for an anatomical depiction of relevant nuclei, the reader is referred to Figure 2 of Schumann, Baumann, and Amaral (2011)) and may provide additional insight into distinct functions of amygdaloid structures. We present the case history, methods of assessment and results, and review studies supporting the amygdala's role in specific phobia.…”

Amygdalar Models of Neurological and Neuropsychiatric Disorders

“…Across a range of studies investigating neurodevelopmental disorders, there is evidence of amygdala dysregulation from postmortem studies, structural MRI analyses, and functional MRI [50].…”

“…Schumann et al [50] conducted a study where autistic adults showed a decrease in neurons in the amygdala compared to control groups. It appears that the amygdala undergoes an abnormal pattern of postnatal development that includes unusual enlargement, followed by a reduction of amygdala size, or decreased neurons, into adulthood.…”