Descriptive Psychopathology: The Signs and Symptoms of ...

62 Section 1: Present, past, and futureto conditioned punishment and frustrative non-reward. The more active thisserotonin modulation, the more behavior is inhibited. Disruption in the behavioralinhibition system is proposed as an explanation for the unwanted repetitivebehaviors that are no longer responsive to conditioning stimuli. 43Anxiety is also proposed to play a role in the pathophysiology of OCD. Themedian raphe nucleus, another major source of serotonin neurons, projects to thelimbic system and hypothalamus modulating noradrenergic functioning andflight/fight mechanisms. Dysfunction in this serotonin system is associated withhigh levels of anxiety that can elicit thoughts of danger and flight/fight behaviorthat disrupts cognition. OCD behaviors can result from disturbed serotonergicmodulation of forebrain and limbic systems or from dysfunction intrinsic tothese systems. Increasing serotonin modulation with selective serotonin reuptakeinhibitor (SSRI) agents is reported helpful in alleviating OCD features. 44Species-specific repetitive automatic and dysfunctional complex feeding,grooming, social, sexual, and predatory behaviors are seen as animal models forOCD. Compulsive self-grooming and licking leading to fur loss and skin lesionsin dogs (canine acral lick) has been successfully treated with SSRI agents. OtherOCD-like behaviors in dogs successfully treated with SSRI agents are running incircles to grasp the tail, nail and foot biting, snapping at imaginary flies, repetitivechewing, and sucking on objects or bodyparts, polydipsia and polyphagia withpica, repetitive digging or scratching, pacing, and rhythmic barking. 45Some captive birds pick their feathers to the degree of self-injury and selfmutilation(i.e. “avian trichotillomania”). Some horses compulsively chew corralfences and “crib” (grasp the fence rail with their teeth and then lean back, tensingneck muscles while air swallowing, endangering their health). Pigs, cows, primates,bears, and elephants in captivity spend hours repetitively biting, chewing,licking, fur pulling, masturbating, and pacing. Great apes in captivity developbehaviors akin to eating disorders and engage in self-injury and self-mutilationand fur pulling. 46 Childhood onset OCD (about 30% of patients) is similar inpresentation to these non-human behaviors. 47The anterior cingulate circuitThe ventral aspect of the anterior cingulate gyrus is associated with emotionalexpression and autonomic function. It has extensive connection with the amygdala,thalamus, nucleus acumbens (involved in hedonistic reward and the abuseof pharmaceuticals), and the ventral striatum (involved in craving and theanticipation of reward). In laboratory animals, lesions in this region are associatedwith an impaired autonomic response to conditioned stimuli and reduced aggression,increased shyness, emotional blunting, reduced motivation, and perturbedmaternal–infant interactions. 48 Dysfunction of the anterior cingulate circuit is