Appetitive Motivational Systems Research Articles

Neuroanatomical correlates of pleasant and unpleasant emotion

Substantial evidence suggests that a key distinction in the classification of human emotion is that between an appetitive motivational system associated with positive or pleasant emotion and an aversive motivational system associated with negative or unpleasant emotion. To explore the neural substrates of these two systems, 12 healthy women viewed sets of pictures previously demonstrated to elicit pleasant, unpleasant and neutral emotion, while positron emission tomographic (PET) measurements of regional cerebral blood flow were obtained. Pleasant and unpleasant emotions were each distinguished from neutral emotion conditions by significantly increased cerebral blood flow in the vicinity of the medial prefrontal cortex (Brodmann's area 9), thalamus, hypothalamus and midbrain ( P<0.005). Unpleasant was distinguished from neutral or pleasant emotion by activation of the bilateral occipito-temporal cortex and cerebellum, and left parahippocampal gyrus, hippocampus and amygdala ( P<0.005). Pleasant was also distinguished from neutral but not unpleasant emotion by activation of the head of the left caudate nucleus ( P<0.005). These findings are consistent with those from other recent PET studies of human emotion and demonstrate that there are both common and unique components of the neural networks mediating pleasant and unpleasant emotion in healthy women.

Affect, Emotional Disorder, and Future-directed Thinking

Affect, it has been argued, can be divided into two higher order dimensions of positive affect (PA) and negative affect (NA) (Watson, L.A. Clark, & Tellegen, 1988). This framework has been used to provide an analysis of depression and anxiety, and has also been integrated with the account of aversive and appetitive motivational systems outlined by Gray (1987) and others (L.A. Clark, Watson, & Mineka, 1994). The present studies represent an attempt to extend this framework to include patterns of future-directed thinking. Two studies are reported in which a sample of students completed measures of PA and NA, depression and anxiety, hopelessness and worry, and positive and negative expectancies. Factor analysis revealed two clear factors. The first factor had loadings from NA, anxiety, worry, negative expectancies, and depression; the smaller second factor had loadings from PA and positive expectancies, and negative loadings from hopelessness and depression. The results support the existence of two basic cognitive-affective systems that also span biological, behavioural, and motivational levels.

Win some, lose some: Parental hypertension and heart rate change in an incentive versus response cost paradigm

Fowles (1983), citing evidence from separate studies, suggests that both incentive and response cost paradigms increase heart rate and should be subsumed under Gray's (1975) ‘appetitive motivational system’. Shock avoidance and loss of reward (response cost) contingencies, while aversive, appear to evoke this motivational system; consequently both should elicit heart rate increases independent of anxiety. The present investigation compared magnitude of heart rate changes observed under conditions of winning and losing money. Results showed: (1) no differences between incentive and response cost conditions; (2) no effect of state anxiety on heart rate in these conditions, despite an elevation of state anxiety on the task day relative to a subsequent relaxation day assessment; and (3) some evidence for the presence under both such appetitive conditions of cardiovascular hyperresponsivity among offspring of hypertensive parents. The results suggest a need for systematic parametric studies of experimental conditions.

Reinstatement of heroin and cocaine self-administration behavior in the rat by intracerebral application of morphine in the ventral tegmental area

In rats trained to self-administer heroin or cocaine intravenously, non-contingent priming injections of heroin or cocaine, respectively, reinstated responding after a period of extinction. In rats similarly trained to self-administer heroin or cocaine intravenously, morphine sulphate was applied centrally to sites in the ventral tegmental area (VTA), the periventricular grey (PVG) and the caudate nucleus following a period of extinction. Self-administration behavior was reinstated by morphine application to sites in the region of the VTA, but not to other sites, in both heroin and cocaine-trained animals. This priming effect of morphine was blocked or attenuated by prior administration of naltrexone, given intraperitoneally. Morphine in the VTA is known to activate mesolimbic dopamine neurons, suggesting that dopamine activity in this system may underline the priming effects of both opiates and stimulants. Furthermore, the fact that the mesolimbic system is implicated in the positive motivational actions of both drug groups, suggests that morphine reinstates drug-taking behavior in these animals by activating appetitive motivational systems of the brain.

The heart beats to reward: the effect of monetary incentive on heart rate.

ABSTRACTTwo experiments are reported which test the hypothesis that heart rate increases will be seen in response to monetary incentives during performance on a continuous motor task. In the first study, heart rate was significantly higher when subjects were paid 2ø for each success feedback compared to subjects who received feedback only. In contrast, there was no effect of varying the probability of success (10% versus 90% success). Study 2 replicated the monetary incentive effect on heart rate, this time employing 100% success feedback. In neither study were subjects' response rates significantly affected by monetary incentive. In addition, control groups responding much faster on the task as a result of making it more predictable did not show increased heart rate. Consequently, these incentive effects are difficult to explain with a cardiac‐somatic coupling interpretation. It was concluded that cardiac acceleration does occur in response to monetary incentives, even in the absence of failure feedback, and it was proposed that this incentive effect reflects the activation of an appetitive motivational system. Possible applications of the assessment of appetitive responses are suggested.

Transfer of Learning across Reinforcers: Appetitive Discrimination Learning between Stimuli Previously Associated with Shock

In each of two experiments rats learned a food-rewarded discrete-trial discrimination in which the correct response in a two-lever Skinner box was signalled by an external stimulus. For one (experimental) group of subjects, one of the stimuli had previously been associated with electric shock while the other had been used to signal the absence of shock. A control group had previously experienced the stimuli uncorrelated with shock. In both experiments its was found that the control subjects learned the discrimination more rapidly than experimental subjects. The relevance of these findings to theories of the acquired distinctiveness of cues and to accounts of interaction between appetitive and aversive motivational systems is discussed.