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Chris D Frith

Publications and source records attributed to Chris D Frith.

At least 19 recordsLinked to original sources
PubMed2006

Dopamine-dependent prediction errors underpin reward-seeking behaviour in humans.

Theories of instrumental learning are centred on understanding how success and failure are used to improve future decisions. These theories highlight a central role for reward prediction errors in updating the values associated with available actions. In animals, substantial evidence indicates that the neurotransmitter dopamine might have a key function in this type of learning, through its ability to modulate cortico-striatal synaptic efficacy. However, no direct evidence links dopamine, striatal activity and behavioural choice in humans. Here we show that, during instrumental learning, the magnitude of reward prediction error expressed in the striatum is modulated by the administration of drugs enhancing (3,4-dihydroxy-L-phenylalanine; L-DOPA) or reducing (haloperidol) dopaminergic function. Accordingly, subjects treated with L-DOPA have a greater propensity to choose the most rewarding action relative to subjects treated with haloperidol. Furthermore, incorporating the magnitude of the prediction errors into a standard action-value learning algorithm accurately reproduced subjects' behavioural choices under the different drug conditions. We conclude that dopamine-dependent modulation of striatal activity can account for how the human brain uses reward prediction errors to improve future decisions.

Adult↗
PubMed2006

Discriminating imagined from perceived information engages brain areas implicated in schizophrenia.

Some of the symptoms of schizophrenia may reflect a difficulty discriminating between information that was perceived from the outside world and information that was imagined. This study used fMRI to examine the brain regions associated with this reality monitoring ability in healthy volunteers, who recollected whether information had previously been perceived or imagined, or whether information had been presented on the left or right of a monitor screen. Recent studies have suggested that schizophrenia may be associated particularly with dysfunction in medial anterior prefrontal cortex, thalamus, and cerebellum. In our data, activation in all three of these regions of interest was significantly greater during recollection of whether stimuli had been perceived or imagined versus recollection of stimulus position. In addition, reduced prefrontal activation was associated with the same misattribution error that has been observed in schizophrenia. These results indicate a possible link between the brain areas implicated in schizophrenia and the regions supporting the ability to discriminate between perceived and imagined information.

Adult↗
PubMed2006

The neural basis of mentalizing.

Mentalizing refers to our ability to read the mental states of other agents and engages many neural processes. The brain's mirror system allows us to share the emotions of others. Through perspective taking, we can infer what a person currently believes about the world given their point of view. Finally, the human brain has the unique ability to represent the mental states of the self and the other and the relationship between these mental states, making possible the communication of ideas.

Brain↗
PubMed2006

How we predict what other people are going to do.

We present a framework for discussing two major aspects of social cognition: the ability to predict what another person is like and what another person is likely to do next. In the first part of this review, we discuss studies that concern knowledge of others as members of a group and as individuals with habitual dispositions. These include studies of group stereotypes and of individual reputation, derived either from experience in reciprocal social interactions such as economic games or from indirect observation and cultural information. In the second part of the review, we focus on processes that underlie our knowledge about actions, intentions, feelings and beliefs. We discuss studies on the ability to predict the course of motor actions and of the intentions behind actions. We also consider studies of contagion and sharing of feelings. Lastly, we discuss studies of spatial and mental perspective taking and the importance of the perception of communicative intent. In the final section of this review, we suggest that the distinction between top-down and bottom-up processes, originally applied to non-social cognitive functions, is highly relevant to social processes. While social stimuli automatically elicit responses via bottom-up processes, responses to the same stimuli can be modulated by explicit instructions via top-down processes. In this way, they provide an escape from the tyranny of strong emotions that are readily aroused in social interactions.

Cognition↗
PubMed2006

Differential components of prospective memory? Evidence from fMRI.

Two of the principal components of prospective memory (i.e., remembering to carry out delayed intentions) are recognizing the appropriate context to act ("cue identification") and remembering the action to be performed ("intention retrieval"). In this experiment, the demands on these components were manipulated while measuring brain activity using fMRI to explore whether the two components share a common neural basis. The results showed significant behavioral differences between the cue identification and intention retrieval conditions. However, a consistent pattern of hemodynamic changes was found in both prospective memory conditions in anterior prefrontal cortex (BA 10), with lateral BA 10 activation accompanied by medial BA 10 deactivation. These effects were more pronounced when demands on intention retrieval were high. This is consistent with the hypothesis that anterior prefrontal cortex (area 10) supports the biasing of attention between external events (e.g., identifying the cue amid distracting stimuli) and internal thought processes (i.e., maintaining the intention and remembering the intended actions). Together, the results suggest that whilst cue identification and intention retrieval may be behaviorally separable, they share at least some common neural basis in anterior prefrontal cortex.

Adolescent↗
PubMed2006

Empathic neural responses are modulated by the perceived fairness of others.

The neural processes underlying empathy are a subject of intense interest within the social neurosciences. However, very little is known about how brain empathic responses are modulated by the affective link between individuals. We show here that empathic responses are modulated by learned preferences, a result consistent with economic models of social preferences. We engaged male and female volunteers in an economic game, in which two confederates played fairly or unfairly, and then measured brain activity with functional magnetic resonance imaging while these same volunteers observed the confederates receiving pain. Both sexes exhibited empathy-related activation in pain-related brain areas (fronto-insular and anterior cingulate cortices) towards fair players. However, these empathy-related responses were significantly reduced in males when observing an unfair person receiving pain. This effect was accompanied by increased activation in reward-related areas, correlated with an expressed desire for revenge. We conclude that in men (at least) empathic responses are shaped by valuation of other people's social behaviour, such that they empathize with fair opponents while favouring the physical punishment of unfair opponents, a finding that echoes recent evidence for altruistic punishment.

Brain↗
PubMed2006

Meeting of minds: the medial frontal cortex and social cognition.

Social interaction is a cornerstone of human life, yet the neural mechanisms underlying social cognition are poorly understood. Recently, research that integrates approaches from neuroscience and social psychology has begun to shed light on these processes, and converging evidence from neuroimaging studies suggests a unique role for the medial frontal cortex. We review the emerging literature that relates social cognition to the medial frontal cortex and, on the basis of anatomical and functional characteristics of this brain region, propose a theoretical model of medial frontal cortical function relevant to different aspects of social cognitive processing.

Animals↗
PubMed2006

Modulation of the mirror system by social relevance.

When we observe the actions of others, certain areas of the brain are activated in a similar manner as to when we perform the same actions ourselves. This 'mirror system' includes areas in the ventral premotor cortex and the inferior parietal lobule. Experimental studies suggest that action observation automatically elicits activity in the observer, which precisely mirrors the activity observed. In this case we would expect this activity to be independent of observer's viewpoint. Here we use whole-head magnetoencephalography (MEG) to record cortical activity of human subjects whilst they watched a series of videos of an actor making a movement recorded from different viewpoints. We show that one cortical response to action observation (oscillatory activity in the 7-12 Hz frequency range) is modulated by the relationship between the observer and the actor. We suggest that this modulation reflects a mechanism that filters information into the 'mirror system', allowing only socially relevant information to pass.

Adult↗
PubMed2005

Activation in posterior superior temporal sulcus parallels parameter inducing the percept of animacy.

An essential, evolutionarily stable feature of brain function is the detection of animate entities, and one of the main cues to identify them is their movement. We developed a model of a simple interaction between two objects, in which an increase of the correlation between their movements varied the amount of interactivity and animacy observers attributed to them. Functional magnetic resonance imaging revealed that activation in the posterior superior temporal sulcus and gyrus (pSTS/pSTG) increased in relation to the degree of correlated motion between the two objects. This activation increase was not different when subjects performed an explicit or implicit task while observing these interacting objects. These data suggest that the pSTS and pSTG play a role in the automatic identification of animate entities, by responding directly to an objective movement characteristic inducing the percept of animacy, such as the amount of interactivity between two moving objects.

Adult↗
PubMed2005

Executive dysfunction in Parkinson's disease is associated with altered pallidal-frontal processing.

Executive dysfunction in Parkinson's disease is well documented, but it is still unclear whether this results from (i) prefrontal dysfunction, (ii) striatal dysfunction, or (iii) altered striatal outflow to the prefrontal cortex. To clarify this issue, we used H(2)(15)O PET to asses six nondemented and nondepressed patients with Parkinson's disease and six matched controls while they performed a task involving executive function, random number generation (RNG), and a control counting task. To assess the effect of increasing task demands, each task was performed at three rates. Both groups showed significant increase in nonrandomness of responses during RNG at faster rates, which was differentially greater for the patients at the faster rate. The controls showed significant activation of the lateral and medial prefrontal cortex and superior and medial parietal cortex during RNG relative to counting. For the same comparison, the patients did not show any activity in medial frontal structures. The controls showed significantly greater mesial frontotemporal activation during counting than RNG, whereas the patients did not show any modulation of regional cerebral blood flow (rCBF) in these areas with task. With faster rates of RNG, the controls showed rCBF increase in the right internal segment of globus pallidus (GPi) and a decrease in frontal cortex. The patients showed the opposite pattern of subcortical and frontal rCBF change with faster rates. The results suggest that executive dysfunction in Parkinson's disease is associated with a failure to modulate frontal activation with increased task demands (nature of task or rate), a deficit associated with altered rCBF in the GPi, the final basal ganglia output pathway to frontal cortex rather than any intrinsic prefrontal dysfunction.

Female↗
PubMed2005

Evidence for sensory prediction deficits in schizophrenia.

OBJECTIVE: Patients with schizophrenia experiencing delusions and hallucinations can misattribute their own actions to an external source. The authors test the hypothesis that patients with schizophrenia have defects in their ability to predict the sensory consequences of their actions. METHOD: The authors measured sensory attenuation of self-produced stimuli by patients with schizophrenia and by healthy subjects. RESULTS: Patients with schizophrenia demonstrated significantly less sensory attenuation than healthy subjects. CONCLUSIONS: Patients with a diagnosis of schizophrenia have a dysfunction in their predictive mechanisms.

Adult↗
PubMed2004

Neural correlates of action attribution in schizophrenia.

Patients with first-rank symptoms (FRS) of schizophrenia do not experience all of their actions and personal states as their own. FRS may be associated with an impaired ability to correctly attribute an action to its origin. In the present study, we examined regional cerebral blood flow (rCBF) with positron emission tomography during an action-attribution task in a group of patients with FRS. We used a device previously used with healthy subjects that allows the experimenter to modulate the subject's degree of movement control (and thus action attribution) of a virtual hand presented on a screen. In healthy subjects, the activity of the right angular gyrus and the insula cortex appeared to be modulated by the subject's degree of movement control of the virtual hand. In the present study, the schizophrenic patients did not show this pattern. We found an aberrant relationship between the subject's degree of control of the movements and rCBF in the right angular gyrus and no modulation in the insular cortex. The implications of these results for understanding pathological conditions such as schizophrenia are discussed.

Adult↗
PubMed2004

Empathy for pain involves the affective but not sensory components of pain.

Our ability to have an experience of another's pain is characteristic of empathy. Using functional imaging, we assessed brain activity while volunteers experienced a painful stimulus and compared it to that elicited when they observed a signal indicating that their loved one--present in the same room--was receiving a similar pain stimulus. Bilateral anterior insula (AI), rostral anterior cingulate cortex (ACC), brainstem, and cerebellum were activated when subjects received pain and also by a signal that a loved one experienced pain. AI and ACC activation correlated with individual empathy scores. Activity in the posterior insula/secondary somatosensory cortex, the sensorimotor cortex (SI/MI), and the caudal ACC was specific to receiving pain. Thus, a neural response in AI and rostral ACC, activated in common for "self" and "other" conditions, suggests that the neural substrate for empathic experience does not involve the entire "pain matrix." We conclude that only that part of the pain network associated with its affective qualities, but not its sensory qualities, mediates empathy.

Adult↗
PubMed2004

Brain responses to the acquired moral status of faces.

We examined whether neural responses associated with judgments of socially relevant aspects of the human face extend to stimuli that acquire their significance through learning in a meaningful interactive context, specifically reciprocal cooperation. During fMRI, subjects made gender judgments on faces of people who had been introduced as fair (cooperators) or unfair (defector) players through repeated play of a sequential Prisoner's Dilemma game. To manipulate moral responsibility, players were introduced as either intentional or nonintentional agents. Our behavioral (likebility ratings and memory performance) as well as our imaging data confirm the saliency of social fairness for human interactions. Relative to neutral faces, faces of intentional cooperators engendered increased activity in left amygdala, bilateral insula, fusiform gyrus, STS, and reward-related areas. Our data indicate that rapid learning regarding the moral status of others is expressed in altered neural activity within a system associated with social cognition.

Adult↗
PubMed2004

Attentional effects of noradrenaline vary with arousal level: selective activation of thalamic pulvinar in humans.

Subjects sedated by noradrenergic alpha2 agonists can switch rapidly from a state of extremely low to almost full consciousness following phasic increases in arousal or cognitive demand. Such flexibility is not displayed by traditional sedatives, such as the benzodiazepine diazepam. Experimentally, the phasic modulation of alpha2 effect by arousing or distracting stimuli can counteract the deleterious cognitive effects of alpha2 agonists. We used behavioural and fMRI indices of brain function to investigate the phasic modulatory effect that presentation of loud white noise would have on attentional dysfunction induced by administration of dexmedotomidine, an alpha2 agonist. Dexmedotomidine and midazolam were compared to placebo during performance of a target detection task, which was presented in the presence or absence of white noise. Compared to placebo, both dexmedotomidine and midazolam impaired task performance. This impairment was significantly attenuated by presentation of white noise in the dexmedotomidine condition only. This functional improvement corresponded to selective increase in activity of left medial pulvinar nucleus of the thalamus. This regional increase is suggested to index increases in phasic arousal, which counteract dexmedotomidine's detrimental attentional effects. Finally, despite sedating subjects to equivalent degrees, dexmedotomidine and midazolam had strikingly different regional effects on task-induced brain activity. Therefore, for the same level of sedation, the behavioural and anatomical attributes identifying the quality of sedation can vary.

Acoustic Stimulation↗
PubMed2004

Activation of the human superior temporal gyrus during observation of goal attribution by intentional objects.

Previous functional imaging experiments in humans showed activation increases in the posterior superior temporal gyrus and sulcus during observation of geometrical shapes whose movements appear intentional or goal-directed. We modeled a chase scenario between two objects, in which the chasing object used different strategies to reach the target object: The chaser either followed the target's path or appeared to predict its end position. Activation in the superior temporal gyrus of human observers was greater when the chaser adopted a predict rather than a follow strategy. Attending to the chaser's strategy induced slightly greater activation in the left superior temporal gyrus than attending to the outcome of the chase. These data implicate the superior temporal gyrus in the identification of objects displaying complex goal-directed motion.

Adult↗