Descriptive Psychopathology: The Signs and Symptoms of ...

72 Section 1: Present, past, and futureA ventral system, including the amygdala, insula, ventral striatum, and ventralaspects of the anterior cingulate gyrus and prefrontal cortex, identifies the salienceof emotion-related stimuli and produces an immediate emotional response and itsassociated autonomic support. Sensory input to this system is from the thalamus tothe amygdala. 88 Motor programs are accessed and appropriate movement to theemotional situation released. When dysfunctional, this system is central to theemergence of mood and anxiety disorders. The abnormal mood states observedin patients with epilepsy are associated with seizure foci in this system.A dorsal system, including the hippocampus, and dorsal aspects of the anteriorcingulate gyrus and prefrontal cortex, regulates the emotional state. Cognitiveprocesses are integrated with and can affect and be affected by the dorsal system.When dysfunctional, this system fails to modulate normal and abnormal emotionalstates. Its intrinsic dysfunction may elicit avolitional or disinhibited syndromes.Executive control of emotion is compromised.The generation of emotionThe generation of emotions reflects a rapid cascade. Potentially emotionallysalient stimuli evoke activation and arousal. Activation is followed by appraisal,i.e. is the situation threatening, is there prey or predator present? This appraisalis immediate and bypasses the cortex. Following appraisal, the appropriateemotional response is generated.Arousal and activation, subserved by the midbrain reticular formation and partof the thalamus, when over-active elicits anxiety. Under-arousal is associated withapathy and stupor. Dysfunction in the arousal subsystem of “go–no go” elicitsbradykinesia, rigidity, and catalepsy. Dysfunction in an “effort” subsystem elicitsavolition and emotional blunting.Appraisal of emotion occurs within awareness (cortical) and out of awareness(subcortical). This process assesses stimuli for their relevance, immediately directsaction in response to salient stimuli, and sends information to the hypothalamus(the head ganglion of the autonomic nervous system) to regulate associatedautonomic support for flight/fight. The amygdala and the insula (a sensoryintegrating area adjacent to the mesial aspect of the temporal lobe) subservethis step. 89The amygdala modulates vigilance and attention to emotionally salient information.90 The insula is involved in fear conditioning, conveying the representationof the aversive sensory experience to the amygdala for further “action”.The insula is involved in the generation of social (secondary) emotions such asdisgust, pride, humiliation, and guilt. 91 Excitatory lesions in the insula elicitgustatory hallucinations of unpleasant tastes, while ablating lesions are associatedwith impaired recognition of facial and vocal emotion. 92