Behavior affiliative

In this chapter we will focus on two basic principles of neurotransmission that may help to understand normal brain function on the one hand, and the current practice of clinical psychopharmacology on the other. First, the anatomic organization of neurotransmitter systems determines their behavioral affiliation. Second, neurotransmitter receptors modulate the electrical properties (via ion channels) or the biochemical properties (via second messenger systems) of neurons. We will then review these two basic principles for some of the neurotransmitter systems relevant to the practice of neuropsychopharmacology. 

Information processing in the human brain via neuro-chemically defined neuronal systems is complex. Therefore, it remains a challenge to conceptualize psychiatric disorders and their treatment in a reductionistic framework of chemical neuroanatomy. We can nonetheless broadly state that the anatomic organization of neurotransmitter systems determines their behavioral affiliation, and that receptors modulate the electrical or biochemical properties of neurons, with direct relevance to the mechanism of action of psychotropic drugs. Future research will provide more detailed information on the subtypes of neurons and specific neurotransmitters systems that are abnormal in psychiatric disorders, and provide a more rational approach to the development of new treatment interventions. 

Kirkpatrick B., Carter C Newman S. and Insel T. (1994). Axon-sparing lesions of the medial nucleus of the amygdala decrease affiliative behaviors in the prairie vole (Microtus ochrogaster) — behavioral and anatomical specificity. Behav Neurosci 108, 501-513. 

Because this hypothesis generated considerable anxiety and had broad pubhc health implications, the Nutrition Foundation (formerly affiliated with the International Life Sciences Institute but now defunct) convened a committee to evaluate the scientific evidence relative to the Feingold hypothesis, and if warranted, provide guidelines for further research. The committee, known as the National Advisory Committee on Hyperkinesis and Food Additives (1975), found no conclusive link between diet and behavior, but could not rule out a possible association since no studies appropriate for testing the hypothesis had been carried out. Based on the committee s recommendations, several doubleblind crossover studies were subsequently conducted, but these produced... 

Wallen, K., and Tannenbaum, P. L. 1996. Hormonal modulation of sexual behavior and affiliation in rhesus monkeys. Annals of the New York Academy of Sciences in press. 

Ellis, S., Pearson, W., Jr. (1988). Race, science, and religious affiliation. Journal of the Association of Social and Behavioral Scientists, 34, 305-317. 

In human beings and most mammals, affiliation is an essential part of the life process, as it is necessary for both reproduction and survival. There are nonetheless instances in nature of profound lack of affiliative behavior. For example, children with autism spectrum disorders have significant difficulties in social skills, including lack of positive reinforcement from social interaction, poor eye gaze, impairment in social interactions, difficulties in attachment, and difficulties in nonverbal and, often, verbal communication. Deficits of this kind have led us to the study of the neurobiology underlying attachment and affiliation. 

Other brain regions are undoubtedly involved in affi-liative behaviors. For example, the ventral temporal area of the cortex appears to be involved in facial discrimination in humans, and abnormalities in the activation of this area during facial discrimination tasks are present in individuals with autism (Schultz et ah, 2000). In rats and other mammals, the olfactory bulb and entorhinal cortex also appear to be involved in affiliative behaviors, including maternal behaviors (Numan, 1994). 

In different species, the OT has been found to influence a wide range of social behaviors, including maternal and paternal behavior, sexual, aggressive and affiliative behaviors, olfactory investigation, and social recognition memory. These relationships are complex, with OT effects, dose-response relationships, and directionality differing across species. In a number of studies, OT infusion has had contrasting effects on the social behaviors of various species (Winslow et ah. 

Oxytocin typically has a facilitative effect on affiliative behaviors (Witt et ah, 1992), including parental and reproductive behaviors and infant-mother attachment. Oxytocin facilitates social memory, with knockout mice displaying social memory deficits it facilitates conditioning to maternal-related olfactory cues (Nelson and Panksepp, 1996). 

Dopamine also appears to be important in affiliative behaviors. Dopamine is well known for its role in the reward systems of the brain, and this role most likely extends to social behaviors as well. In prairie voles, the Dj receptors appear to play an important role in partner preference formation after mating (Insel and Young, 2001). The specific role has yet to be elucidated, however, agonists can facilitate this behavior and antagonists of the D2 receptor can inhibit it. 

Although social attachment and impairment of social behaviors are evident in a wide range of psychopathology, including childhood trauma, personality disorders, and anxiety disorders, an extensive review of this subject is beyond the scope of this chapter. The focus of this section will thus be primarily limited to the neurobiology of affiliation as it relates to autism spectrum disorders. 

Additionally, an opioid antagonist, naltrexone, has been used to treat children with autism. The results from these studies have been mixed, with some studies showing a mild decrease in hyperactivity and self-injurious behavior, and improved attention (Gillberg, 1995). The children who respond best to this medication appear to have more severe abnormalities in their beta endorphin levels (Bouvard et al., 1995). Overall, the research suggests that the endogenous opioid system, which is important in the reward aspects of affiliation, may also play a role in the neurobiology of autism. 

Insel, T.R., and Winslow J.T. (1998) Serotonin and neuropeptides in affiliative behaviors. Biol Psychiatry 443 207-219. 

Knutson, B., Cole, S., Wolkowitz, O., Reus, V., Chan, T, and Moore, E. (1997) Serotonergic intervention increases affiliative behavior in humans. Ann NY Acad Sci 807 492—493. 

Shapiro, L.E., and Insel, T.R. (1990) Infant s tesponse to social separation reflects adult differences in affiliative behavior a comparative developmental study in praitie and montane voles. Dev Psychobiol 23 374—394. 

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