ReviewEscalated aggressive behavior: Dopamine, serotonin and GABA
Section snippets
Definitions and ethics
In most general terms, aggressive behavior can be considered as a behavior that inflicts harm and injury or threatens to do so (Berkowitz, 1983). One important class of aggressive behavior is characterized by its instrumentality, typically in a reproductive context; males achieve dominance in a social setting by engaging in aggressive displays; in other animal species, males patrol and defend territories in order to secure the resources that attract breeding partners, while females suppress the
Approaches to study aggression
It is ethically not acceptable to recreate clinically relevant types of aggressive behavior in the experimental human laboratory in real time. Most studies use simulations of symbolic and moderate forms of aggression towards a fictitious competitor (Cherek and Steinberg, 1987), neuroimaging of individuals who have displayed in the past high levels of aggressive behavior (Soloff et al., 2005, George et al., 2004). Alternatively, individuals with a criminal history or in drug abusers are studied (
Preclinical aggression research
Early laboratory studies of animal aggression began by inducing intense aggressive and defensive reactions in otherwise placid laboratory animals by brain lesions or electrical brain stimulation, by provoking animals with noxious painful stimuli or housing them in isolation for prolonged periods, or by exposing them to frustrating experiences (e.g., Valzelli, 1973, Yen et al., 1959, Ulrich, 1966, Ulrich and Azrin, 1962, Azrin et al., 1966, Hess and Brugger, 1943, Koolhaas, 1978, Brady and
Types of escalated aggression
In social species, the aggressive behavior can serve an important adaptive function. Nevertheless, when this type of behavior exceeds the species-typical pattern, it becomes maladaptive. Escalated or excessive levels of aggressive behavior can be induced in laboratory animals or humans by (a) pharmacological (alcohol-heightened aggression), (b) environmental (social instigation), (c) behavioral (frustration-induced aggression) means or (d) by genetic selection (de Boer and Koolhaas, 2005—this
Escalated forms of aggression and neurotransmitters
The role of neurotransmitters and their receptors and transport sites in preclinical studies of aggression has guided much of the development of pharmacotherapeutic interventions during the past decades (Miczek et al., 2002). The focus on the canonical aminergic transmitters such as dopamine, norepinephrine and serotonin, while still the basis for current drug treatments of violent individuals, has been complemented by a better understanding of modulatory influences by glutamate and GABA as
Conclusions
From an ethological perspective, the term “violence” is not relevant, since its focus is on adaptive forms of aggressive behavior, which are significant in terms of the individual's survival and reproduction. Animal models of hostile and violent symptoms in psychiatric disorders are necessary in order to be relevant to the study of the neurobiological basis of human violence.
The recent observations point to serotonin receptor subtypes such as the 5-HT1B receptor as particularly important for
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