شعاع شکمی بادامه مغز: مربوطه به تکانش و خشونت

Investigations into the specific association of amygdala volume, a critical aspect of the fronto-limbic emotional circuitry, and aggression have produced results broadly consistent with the ‘larger is more powerful’ doctrine. However, recent reports suggest that the ventral and dorsal aspects of the amygdala play functionally specific roles, respectively, in the activation and control of behavior. Therefore, parceling amygdala volume into dorsal and ventral components might prove productive in testing hypotheses regarding volumetric association to aggression, and impulsivity, a related aspect of self-control. We sought to test this hypothesis in a group of 41 psychiatric patients who received standard magnetic resonance imaging and a psychometric protocol including aggression and impulsivity measures. Whole amygdala volumes were not associated with aggression or impulsivity, but significant correlations were found when dorsal/ventral amygdalae were analyzed separately. Specifically, left and right ventral amygdala volume was positively associated with motor impulsivity, and left dorsal amygdala was negatively associated with aggression. Results are discussed in terms of an activation and control model of brain-behavior relations. Potential relevance to the continuum of amygdala hyper- to hypo-activation and aggression is discussed.

Dysfunction of the limbic system, including the amygdala and hippocampus, has been implicated in aggression (Bear, 1991) and in the functional and clinical neuroanatomy of morality (Fumagalli and Priori, 2012). The amygdala and inter-connected cortical areas play an important role in perceiving and responding to threatening stimuli and in regulating aggressive behavior in humans (Goldstein et al., 1996 and LeDoux, 2000) and other species (Kluver and Bucy, 1939, Adamec, 1991, Gregg and Siegel, 2001 and Saddoris et al., 2005). The structure–function relationship of the amygdala and related structures to the aggressive behavior of antisocial individuals has been extensively reviewed (Raine and Yang, 2006). Among healthy controls the strength of the coupled activity of the amygdala with the orbital frontal cortex or the dorsomedial cortex is related to the degree of attenuation of negative affect generated during emotional re-appraisal (Banks et al., 2007). Siever (2008) reviewed evidence suggesting that aggression is, in part, a result of amygdala activation in the absence of top-down controls, a phenomenon sometimes referred to as dual-brain pathology (Tebartz van Elst et al., 2001).

Aggression and impulsivity were modestly associated with one another (r=0.3, P=0.05), as were aggression and years of education (r=−0.37, P<0.05). Age was not associated with total amygdala volume, aggression, or impulsivity. Handedness was significantly associated with left amygdala volume (t[32]=2.19, P<0.05), but not right volume (t[32]=0.26, P>0.05). Handedness was partialled out of the total, dorsal, and ventral, left amygdala correlations. TICV was partialled out of all ROI volumes to trait correlations.