"Identifying Emotions on the Basis of Neural Activation"
PLOS One, 2013:1
Mouse over here for a brief summary or click to open article in a new tab.We attempt to determine the discriminability and organization of neural activation corresponding to the experience of specific emotions. Method actors were asked to self-induce nine emotional states (anger, disgust, envy, fear, happiness, lust, pride, sadness, and shame) while in an fMRI scanner. Using a Gaussian Naïve Bayes pooled variance classifier, we demonstrate the ability to identify specific emotions experienced by an individual at well over chance accuracy on the basis of: 1) neural activation of the same individual in other trials, 2) neural activation of other individuals who experienced similar trials, and 3) neural activation of the same individual to a qualitatively different type of emotion induction. Factor analysis identified valence, arousal, sociality, and lust as dimensions underlying the activation patterns. These results suggest a structure for neural representations of emotion and inform theories of emotional processing.
Archive: May 2013
"Limited Encoding of Effort by Dopamine Neurons in a Cost-Benefit Trade-off Task"
The Journal of Neuroscience, 33(19):8288-8300
Mouse over here for a brief summary or click to open article in a new tab.Animals are thought to evaluate the desirability of action options using a unified scale that combines predicted benefits (“rewards”),
costs, and the animal’s internal motivational state. Midbrain dopamine neurons have long been associated with the reward part of this
equation, but it is unclear whether these neurons also estimate the costs of taking an action. We studied the spiking activity of dopamine
neurons in the substantia nigra pars compacta of monkeys (Macaca mulatta) during a reaching task in which the energetic costs incurred
(friction loads) and the benefits gained (drops of food) were manipulated independently. Although the majority of dopamine neurons
encoded the upcoming reward alone, a subset predicted net utility of a course of action by signaling the expected reward magnitude
discounted by the invested cost in terms of physical effort. In addition, the tonic activity of some dopamine neurons was slowly reduced
in conjunction with the accumulated trials, which is consistent with the hypothesized role for tonic dopamine in the invigoration or
motivation of instrumental responding. The present results shed light on an often-hypothesized role for dopamine in the regulation of the
balance in natural behaviors between the energy expended and the benefits gained, which could explain why dopamine disorders, such as
Parkinson’s disease, lead to a breakdown of that balance.