Anxiety disorders are characterized by excessive attention to threat. Several brain areas, including the orbitofrontal cortex (OFC), have been associated with threat processing, with more recent work implicating specialized roles for the medial and lateral subregions of the OFC in mediating specific symptoms of anxiety disorders. Virtually no causal work, however, has evaluated the role of these OFC subregions in regulating behavioral responses under threat. To address this gap, we compared male rhesus monkeys (Macaca mulatta) with bilateral excitotoxic lesions restricted to either the lateral OFC (lOFC), targeting Walker's areas 11 and 13, or the medial OFC (mOFC), targeting Walker's area 14, to a group of unoperated controls on behavioral responses to the presentation of a fake rubber snake, fake spider, and neutral stimuli. Both lesion groups showed heightened defensive and reduced approach responses, accompanied by longer latencies to retrieve a food reward, in the presence of the threatening stimuli. Compared to unoperated controls, the mOFC lesion group also showed longer latencies to reach for rewards and a greater proportion of defensive responses (e.g., piloerection) in the presence of neutral stimuli. Thus, monkeys with mOFC lesions displayed a greater tendency to express defensive responses even in the absence of threat. Overall, our data reveal that both the mOFC and lOFC contribute to the attenuation of defensive responses. Notably, these findings, obtained following selective, excitotoxic lesions of the OFC, are diametrically opposed to the effects of aspiration lesions of OFC observed in macaques.
Evidence is mixed regarding differences in prevalence of aggressive behavior, with many (though not all) studies suggesting that men are more aggressive than women. Furthermore, while aggression often occurs in response to provocation-induced anger, this relationship may be stronger for men; women may be more likely to engage in non-aggressive (e.g., affiliative) behaviors in response to provocation, particularly at low-level provocation. This study examined gender differences in aggression as well as differences in the relationship between anger and aggression for men and women. Adults ( N = 424) participated in a behavioral aggression task, and a subset of participants ( n = 304) completed a questionnaire assessing trait levels of anger as part of a larger study at a large midwestern university. Results indicated that while men and women aggressed at similar levels, aggression was significantly associated with trait anger for men only, at low levels of provocation, with only a trending relationship for high provocation. This suggests that while men and women may be equally aggressive in certain situations, this behavior may be differentially associated with anger.
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