Successful social interaction requires recognizing subtle changes in the mental states of others.... more Successful social interaction requires recognizing subtle changes in the mental states of others. Deficits in emotion recognition are found in several neurological and psychiatric illnesses, and are often marked by disturbances in gaze patterns to faces, typically interpreted as a failure to fixate on emotionally informative facial features. However, there has been very little research on how fixations inform emotion recognition in healthy people. Here, we asked whether fixations predicted detection of subtle and extreme emotions in faces. We used a simple model to predict emotion detection scores from participants' fixation patterns. The best fit of this model heavily weighted fixations to the eyes in detecting subtle fear, disgust and surprise, with less weight, or zero weight, given to mouth and nose fixations. However, this model could not successfully predict detection of subtle happiness, or extreme emotional expressions, with the exception of fear. These findings argue th...
Adjusting for an error requires both disengaging from the wrong course of action and initiating a... more Adjusting for an error requires both disengaging from the wrong course of action and initiating a corrective response. The dorsal anterior cingulate cortex (dACC) has been implicated in both these processes in the decision-making and action monitoring literatures. Here, we aimed to distinguish between these putative functions with a variant of the Eriksen flanker task that manipulated response requirements (i.e. one or two finger responses). We found that two event-related potentials originating from the dACC (error-related negativity (ERN) and anterior N2) only reflected the representation of the incorrect response: these waveforms were larger when the incorrect response involved two fingers rather than one finger. The increase in ERN magnitude was also accompanied by a reduction in spontaneous error corrections. These results argue that activity in the dACC reflects a process involved in disengaging from an ongoing incorrect action, clearing the way for the correct response.
Effective self-control relies on the rapid adjustment of inappropriate responses. Understanding t... more Effective self-control relies on the rapid adjustment of inappropriate responses. Understanding the brain basis of these processes has the potential to inform neurobiological models of the many neuropsychiatric disorders that are marked by maladaptive responding. Research on error processing in particular has implicated the dorsomedial frontal lobe (DMF) and basal ganglia (BG) in error detection, inhibition and correction. However there is controversy regarding the specific contributions of these regions to each of these component processes. Here we examined the effects of lesions affecting DMF or BG on these error-related processes. A flanker task was used to induce errors that in turn led to spontaneous, online corrections, while response kinematics were measured with high spatiotemporal resolution. The acceleration of errors was initially greater than that of correct responses. Errors then showed slower acceleration compared to correct responses, consistent with engagement of inh...
International journal of obesity (2005), Jan 16, 2014
Background:Poor inhibitory control is associated with overeating and/or obesity in school-age chi... more Background:Poor inhibitory control is associated with overeating and/or obesity in school-age children, adolescents and adults. The current study examined whether an objective and reliable marker of response inhibition, the stop-signal reaction time (SSRT), is associated with body mass index (BMI) z-scores and/or food intake during a snack test in pre-school children.Methods:The current sample consisted of 193 pre-school children taking part in a longitudinal study of early brain development (Maternal Adversity, Vulnerability and Neurodevelopment (the MAVAN project)). Linear mixed-effect models were used to examine whether the SSRT measured at age 48 months associated with BMI z-scores and/or dietary intake during a laboratory-based snack test.Results:After controlling for significant covariates including maternal BMI, there was a significant gender by SSRT interaction effect in predicting 48-month BMI z-scores. Post-hoc analysis revealed an association between longer SSRTs (poor re...
Adaptive decision making involves selecting the most valuable option, typically by taking an acti... more Adaptive decision making involves selecting the most valuable option, typically by taking an action. Such choices require value comparisons, but there is debate about whether these comparisons occur at the level of stimuli (goods-based) value, action-based value, or both. One view is that value processes occur in series, with stimulus value informing action value. However, lesion work in nonhuman primates suggests that these two kinds of choice are dissociable. Here, we examined action-value and stimulus-value learning in humans with focal frontal lobe damage. Orbitofrontal damage disrupted the ability to sustain the correct choice of stimulus, but not of action, after positive feedback, while damage centered on dorsal anterior cingulate cortex led to the opposite deficit. These findings argue that there are distinct, domain-specific mechanisms by which outcome value is applied to guide subsequent decisions, depending on whether the choice is between stimuli or between actions.
The factors that affect food choices are critical to understanding obesity. In the present study,... more The factors that affect food choices are critical to understanding obesity. In the present study, healthy participants were shown pictures of foods to determine the impact of caloric content on food choice. Brain activity was then measured while participants bid for a chance to purchase and eat one item. True caloric density, but not individual estimates of calorie content, predicted how much participants were willing to pay for each item. Caloric density also correlated with the neural response to food pictures in the ventromedial prefrontal cortex, a brain area that encodes the value of stimuli and predicts immediate consumption. That same region exhibited functional connectivity with an appetitive brain network, and this connectivity was modulated by willingness to pay. Despite the fact that participants were poor at explicitly judging caloric content, their willingness to pay and brain activity both correlated with actual caloric density. This suggests that the reward value of a...
The extent to which we learn from positive and negative outcomes of decisions is modulated by the... more The extent to which we learn from positive and negative outcomes of decisions is modulated by the neurotransmitter dopamine. Dopamine neurons burst fire in response to unexpected rewards and pause following negative outcomes. This dual signaling mechanism is hypothesized to drive both approach and avoidance behavior. Here we test a prediction deriving from a computational reinforcement learning model, in which approach is mediated via activation of the direct cortico-striatal pathway due to striatal D1 receptor stimulation, while avoidance occurs via disinhibition of indirect pathway striatal neurons secondary to a reduction of D2 receptor stimulation. Using positron emission tomography with two separate radioligands, we demonstrate that individual differences in human approach and avoidance learning are predicted by variability in striatal D1 and D2 receptor binding, respectively. Moreover, transient dopamine precursor depletion improved learning from negative outcomes. These findi...
Methods: To test this hypothesis we scanned 28 human normal weight participants using event relat... more Methods: To test this hypothesis we scanned 28 human normal weight participants using event related fMRI (Siemens Trio 3T), while they bid for the right to purchase food items and trinkets in two different conditions: once following iv injection of ghrelin and again after a ...
Successful social interaction requires recognizing subtle changes in the mental states of others.... more Successful social interaction requires recognizing subtle changes in the mental states of others. Deficits in emotion recognition are found in several neurological and psychiatric illnesses, and are often marked by disturbances in gaze patterns to faces, typically interpreted as a failure to fixate on emotionally informative facial features. However, there has been very little research on how fixations inform emotion recognition in healthy people. Here, we asked whether fixations predicted detection of subtle and extreme emotions in faces. We used a simple model to predict emotion detection scores from participants' fixation patterns. The best fit of this model heavily weighted fixations to the eyes in detecting subtle fear, disgust and surprise, with less weight, or zero weight, given to mouth and nose fixations. However, this model could not successfully predict detection of subtle happiness, or extreme emotional expressions, with the exception of fear. These findings argue th...
Adjusting for an error requires both disengaging from the wrong course of action and initiating a... more Adjusting for an error requires both disengaging from the wrong course of action and initiating a corrective response. The dorsal anterior cingulate cortex (dACC) has been implicated in both these processes in the decision-making and action monitoring literatures. Here, we aimed to distinguish between these putative functions with a variant of the Eriksen flanker task that manipulated response requirements (i.e. one or two finger responses). We found that two event-related potentials originating from the dACC (error-related negativity (ERN) and anterior N2) only reflected the representation of the incorrect response: these waveforms were larger when the incorrect response involved two fingers rather than one finger. The increase in ERN magnitude was also accompanied by a reduction in spontaneous error corrections. These results argue that activity in the dACC reflects a process involved in disengaging from an ongoing incorrect action, clearing the way for the correct response.
Effective self-control relies on the rapid adjustment of inappropriate responses. Understanding t... more Effective self-control relies on the rapid adjustment of inappropriate responses. Understanding the brain basis of these processes has the potential to inform neurobiological models of the many neuropsychiatric disorders that are marked by maladaptive responding. Research on error processing in particular has implicated the dorsomedial frontal lobe (DMF) and basal ganglia (BG) in error detection, inhibition and correction. However there is controversy regarding the specific contributions of these regions to each of these component processes. Here we examined the effects of lesions affecting DMF or BG on these error-related processes. A flanker task was used to induce errors that in turn led to spontaneous, online corrections, while response kinematics were measured with high spatiotemporal resolution. The acceleration of errors was initially greater than that of correct responses. Errors then showed slower acceleration compared to correct responses, consistent with engagement of inh...
International journal of obesity (2005), Jan 16, 2014
Background:Poor inhibitory control is associated with overeating and/or obesity in school-age chi... more Background:Poor inhibitory control is associated with overeating and/or obesity in school-age children, adolescents and adults. The current study examined whether an objective and reliable marker of response inhibition, the stop-signal reaction time (SSRT), is associated with body mass index (BMI) z-scores and/or food intake during a snack test in pre-school children.Methods:The current sample consisted of 193 pre-school children taking part in a longitudinal study of early brain development (Maternal Adversity, Vulnerability and Neurodevelopment (the MAVAN project)). Linear mixed-effect models were used to examine whether the SSRT measured at age 48 months associated with BMI z-scores and/or dietary intake during a laboratory-based snack test.Results:After controlling for significant covariates including maternal BMI, there was a significant gender by SSRT interaction effect in predicting 48-month BMI z-scores. Post-hoc analysis revealed an association between longer SSRTs (poor re...
Adaptive decision making involves selecting the most valuable option, typically by taking an acti... more Adaptive decision making involves selecting the most valuable option, typically by taking an action. Such choices require value comparisons, but there is debate about whether these comparisons occur at the level of stimuli (goods-based) value, action-based value, or both. One view is that value processes occur in series, with stimulus value informing action value. However, lesion work in nonhuman primates suggests that these two kinds of choice are dissociable. Here, we examined action-value and stimulus-value learning in humans with focal frontal lobe damage. Orbitofrontal damage disrupted the ability to sustain the correct choice of stimulus, but not of action, after positive feedback, while damage centered on dorsal anterior cingulate cortex led to the opposite deficit. These findings argue that there are distinct, domain-specific mechanisms by which outcome value is applied to guide subsequent decisions, depending on whether the choice is between stimuli or between actions.
The factors that affect food choices are critical to understanding obesity. In the present study,... more The factors that affect food choices are critical to understanding obesity. In the present study, healthy participants were shown pictures of foods to determine the impact of caloric content on food choice. Brain activity was then measured while participants bid for a chance to purchase and eat one item. True caloric density, but not individual estimates of calorie content, predicted how much participants were willing to pay for each item. Caloric density also correlated with the neural response to food pictures in the ventromedial prefrontal cortex, a brain area that encodes the value of stimuli and predicts immediate consumption. That same region exhibited functional connectivity with an appetitive brain network, and this connectivity was modulated by willingness to pay. Despite the fact that participants were poor at explicitly judging caloric content, their willingness to pay and brain activity both correlated with actual caloric density. This suggests that the reward value of a...
The extent to which we learn from positive and negative outcomes of decisions is modulated by the... more The extent to which we learn from positive and negative outcomes of decisions is modulated by the neurotransmitter dopamine. Dopamine neurons burst fire in response to unexpected rewards and pause following negative outcomes. This dual signaling mechanism is hypothesized to drive both approach and avoidance behavior. Here we test a prediction deriving from a computational reinforcement learning model, in which approach is mediated via activation of the direct cortico-striatal pathway due to striatal D1 receptor stimulation, while avoidance occurs via disinhibition of indirect pathway striatal neurons secondary to a reduction of D2 receptor stimulation. Using positron emission tomography with two separate radioligands, we demonstrate that individual differences in human approach and avoidance learning are predicted by variability in striatal D1 and D2 receptor binding, respectively. Moreover, transient dopamine precursor depletion improved learning from negative outcomes. These findi...
Methods: To test this hypothesis we scanned 28 human normal weight participants using event relat... more Methods: To test this hypothesis we scanned 28 human normal weight participants using event related fMRI (Siemens Trio 3T), while they bid for the right to purchase food items and trinkets in two different conditions: once following iv injection of ghrelin and again after a ...
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