Functional Ensemble of Temperament
Functional Ensemble of Temperament is a neurochemical model suggesting specific functional roles of main neurotransmitter systems in the regulation of behaviour.
Earlier theories
Medications can adjust the release of brain neurotransmitters in cases of depression, anxiety disorder, schizophrenia and other mental disorders because an imbalance within neurotransmitter systems can emerge as consistent characteristics in behaviour compromising people's lives. All people have a weaker form of such imbalance in at least one of such neurotransmitter systems that make each of us distinct from one another. The impact of this weak imbalance in neurochemistry can be seen in the consistent features of behaviour in healthy people. In this sense temperament and mental illness represents varying degrees along the same continuum of neurotransmitter imbalance in neurophysiological systems of behavioural regulation.In fact, multiple temperament traits have been linked to brain neurotransmitters and hormone systems.
By the end of the 20th century, it became clear that the human brain operates with more than a dozen neurotransmitters and a large number of neuropeptides and hormones. The relationships between these different chemical systems are complex as some of them suppress and some of them induce each other's release during neuronal exchanges. This complexity of relationships devalues the old approach of assigning “inhibitory vs. excitatory” roles to neurotransmitters: the same neurotransmitters can be either inhibitory or excitatory depending on what system they interact with. It became clear that an impressive diversity of neurotransmitters and their receptors is necessary to meet a wide range of behavioural situations, but the links between temperament traits and specific neurotransmitters are still a matter of research. Several attempts were made to assign specific neurotransmitters to specific traits. For example, dopamine was proposed to be a neurotransmitter of the trait of Extraversion, noradrenaline was linked to anxiety, and serotonin was thought to be a neurotransmitter of an inhibition system. These assignments of neurotransmitter functions appeared to be an oversimplification when confronted by the evidence of much more diverse functionality.
Research groups led by Petra Netter in Germany, Lars Farde in Karolinska Institute in Sweden and Trevor Robbins in Cambridge, UK had most extensive studies of the links between temperament/personality traits or dynamical properties of behavior and groups of neurotransmitters.
Development of the FET model
The architecture of the Functional Ensemble of Temperament was developed by Trofimova as the Compact version of the Structure of Temperament Questionnaire in 1997–2007. This model inherits the activity-specific approach to the structure of temperament proposed by Rusalov in mid-1980s. According to this approach, the traits of temperament related to motor-physical, social-verbal and mental aspects of activities are based on different neurophysiological systems and should be assessed separately. The final STQ-77/FET model considers 12 systems : 9 systems regulating the formal functional aspects of behaviour together with 3 systems related to emotionality .The differences between Trofimova's and Rusalov's models of temperament are:
- the choice of the grouping of temperament traits by three dynamical aspects, presented as three columns in the Figure;
- a presence of orientation-related traits in Trofimova's model which were not included in Rusalov's model. These traits describe the behavioural orientation of a person with preferences to specific types of reinforcers: sensations, other people's state or knowledge about causes of natural processes.
- a different structure of the traits related to emotionality. FET considers emotionality traits as systems amplifying three dynamical aspects of behaviour presented in the three columns of the model. Amplification of orientation aspects emerges in the trait of Neuroticism; amplification of speed of integration emerges as Impulsivity and amplification of subjective feeling of energetic capacities emerges in the trait of Satisfaction.
In 2007–2013 this STQ-77 model of temperament was reviewed and compared to the main findings in neurophysiology, neurochemistry, clinical psychology and kinesiology resulting in the neurochemical FET model offered by Irina Trofimova, McMaster University. Trevor Robbins, Cambridge University who collaborated with Trofimova on this project in 2014–2016 suggested a revision of the part of the FET neurochemical hypothesis related to the trait of Intellectual Endurance. This neurochemical component of the FET hypothesis was upgraded in 2015 by underlying a key role of acetylcholine and noradrenalin in sustained attention. In February 2018, by the suggestion of Dr Marina Kolbeneva the scale Self-Confidence was renamed as the scale of dispositional Satisfaction.
Overview of the model
The final STQ-77/FET model considers 12 systems : nine systems regulating the formal functional aspects of behaviour each assessed in three domains together with three systems related to emotionality . The FET hypothesis suggests that the nine non-emotionality traits are regulated by the monoamines , acetylcholine and neuropeptide systems, whereas the three emotionality-related traits emerge as a dysregulation of opioid receptors systems that have direct control over MA systems. Importantly, the FET model suggests that there is no one-to-one correspondence between the neurotransmitter systems underlying temperament traits but instead specific ensemble relationships between these systems emerge as temperament traits.The FET hypothesis is based only on the strongest consensus points in the research studying the role of neurotransmitter in behavioural regulation and the components of temperament; it doesn't list more controversial links between these multiple systems.
| Temperament trait | Description | Hypothesized links to neurochemical systems † |
| Behavioral orientation traits | NA +... | |
| Sensation seeking | behavioral orientation to well-defined and existing sensational objects and events, underestimation of outcomes of risky behaviour | + cortisol, AdrR, DA, PRL-NPY interactions |
| Empathy | behavioral orientation to the emotional states/needs of others | Possible action of OXY, ADH, MOPr interacting with the NA system |
| Sensitivity to Probabilities | the drive to gather information about commonality, frequency and values of events, to differentiate their specific features, to project these features in future actions | Interaction between neocortical NA, DA, 5-HT and ACh systems |
| Speed of action-integration traits | DA +... | |
| Physical Tempo | speed of integration of an action in physical manipulations with objects with well-defined scripts of actions | DA-PRL, DA-GABA /Glu interaction in basal ganglia, DOPr |
| Social-verbal Tempo | the preferred speed of speech and ability to understand fast speech on well-known topics, reading and sorting of known verbal material | OXY, ADH and PRL under DA control, especially in dorsal striatum |
| Plasticity | the ability to adapt quickly to changes in situations, to change the program of action, and to shift between different tasks | DA-5-HT interaction in the cortex-basal ganglia networks |
| Maintenance of activity traits | 5-HT, ACh +... | |
| Physical Endurance | the ability of an individual to sustain prolonged physical activity using well-defined behavioral elements | 5-HT, ACh, GH-SOM, orexins |
| Social-verbal Endurance | sociability; the ability of an individual to sustain prolonged social-verbal activities using well-defined behavioral elements | 5-HT, OXY, ADH, GH-PRL, orexins |
| Mental Endurance | the ability to stay focused on selected features of objects with suppression of behavioral reactivity to other features | Neocortical NA-ACh |
| Emotional amplifier traits | Opioid receptor systems +... | |
| Neuroticism | A tendency to avoid novelty, unpredictable situations and uncertainty | KOPr > MOPr imbalance →NA-HPA |
| Impulsivity | Initiation of actions based on immediate emotional reactivity | DOPr→ |
| Satisfaction | A sense of security, disposition for a good mood; in high values – overconfidence with negligence to details | KOPr < MOPr →, SOM |
† Neurotransmitter systems: 5-HT: serotonin; DA: dopamine; NE: noradrenalin; ACh: acetylcholine; Glu: glutamate; GH: Growth Hormone; SOM: Somatostatin; PRL: prolactin; OXY: oxytocin; ADH: vasopressin; SubP: Substance P; NPY: Neuropeptide Y; KOPr, MOPr, DOPr: kappa-, mu- and delta-opioid receptors correspondingly; AdrR - adrenergic receptors.