Showing papers by "Chris D. Frith published in 1996"
TL;DR: Direct in vivo evidence of a differential neural response in the human amygdala to facial expressions of fear and happiness is reported, providing direct evidence that the humangdala is engaged in processing the emotional salience of faces, with a specificity of response to fearful facial expressions.
Abstract: The amygdala is thought to play a crucial role in emotional and social behaviour. Animal studies implicate the amygdala in both fear conditioning and face perception. In humans, lesions of the amygdala can lead to selective deficits in the recognition of fearful facial expressions and impaired fear conditioning, and direct electrical stimulation evokes fearful emotional responses. Here we report direct in vivo evidence of a differential neural response in the human amygdala to facial expressions of fear and happiness. Positron-emission tomography (PET) measures of neural activity were acquired while subjects viewed photographs of fearful or happy faces, varying systematically in emotional intensity. The neuronal response in the left amygdala was significantly greater to fearful as opposed to happy expressions. Furthermore, this response showed a significant interaction with the intensity of emotion (increasing with increasing fearfulness, decreasing with increasing happiness). The findings provide direct evidence that the human amygdala is engaged in processing the emotional salience of faces, with a specificity of response to fearful facial expressions.
1,954 citations
TL;DR: Mentalizing ability was studied in symptomatic schizophrenic patients and non-symptomatic controls, consistent with the hypothesis that certain of the positive symptoms of schizophrenia reflect an impairment in the ability to infer the mental states of others.
Abstract: Mentalizing ability was studied in 46 symptomatic schizophrenic patients and 44 non-symptomatic controls. Subjects heard six stories and simultaneously were shown simple cartoon pictures depicting the action sequencing occurring in the stories. All the stories involved false belief or deception, so that it was necessary to infer the mental states of the characters in order to understand their behaviour. After each story, subjects were asked one memory/reality question (concerning an event in the story) and one question that depended on the ability to infer the mental state of one of the characters. Patients with paranoid delusions were impaired on the questions concerning mental states. Patients with behavioural signs (i.e. negative features or incoherence) were also impaired on the mental state questions, but this difficulty was associated with memory impairments. Patients with symptoms of passivity (e.g. delusions of control) and patients in remission did not differ from normal controls. These results are consistent with the hypothesis that certain of the positive symptoms of schizophrenia reflect an impairment in the ability to infer the mental states of others.
814 citations
TL;DR: The functional anatomy of planning was investigated using the Tower of London task and enhanced neural activity in both this rostral prefrontal area and the visuospatial working memory system was associated with increased task difficulty.
642 citations
TL;DR: The independent activation of the posterior and anterior speech areas in dyslexics supports the notion that representations of unsegmented and segmented phonology are functionally and anatomically separate.
Abstract: Summary A rhyming and a short-term memory task with visually presented letters were used to study brain activity in five compensated adult developmental dyslexics. Their only cognitive difficulty was in phonological processing, manifest in a wide range of tasks including spoonerisms, phonemic fluency and digit naming speed. PET scans showed that for the dyslexics, a subset only of the brain regions normally involved in phonological processing was activated: Broca 's area during the rhyming task, temporo-parietal cortex during the short-term memory task. In contrast to normal controls these areas were not activated in concert. Furthermore the left insula was never activated. We propose that the defective phonological system of these dyslexics is due to weak connectivity between anterior and posterior language areas. This could be due to a dysfunctional left insula which may normally act as an anatomical bridge between Broca's area, superior temporal and inferior parietal cortex. The independent activation of the posterior and anterior speech areas in dyslexics supports the notion that representations of unsegmented and segmented phonology are functionally and anatomically separate.
625 citations
TL;DR: Five patients with Asperger syndrome with mild variant of autism with normal intellectual functioning were studied, and no task-related activity was found in this region of left medial prefrontal cortex, but normal activity was observed in immediately adjacent areas.
Abstract: THE ability to attribute mental states to others ('theory of mind') pervades normal social interaction and is impaired in autistic individuals In a previous positron emission tomography scan study of normal volunteers, performing a 'theory of mind' task was associated with activity in left medial prefrontal cortex We used the same paradigm in five patients with Asperger syndrome, a mild variant of autism with normal intellectual functioning No task-related activity was found in this region, but normal activity was observed in immediately adjacent areas This result suggests that a highly circumscribed region of left medial prefrontal cortex is a crucial component of the brain system that underlies the normal understanding of other minds
581 citations
TL;DR: The functional anatomy of the RVIP task is investigated using positron emission tomography derived measures of regional cerebral blood flow (rCBF) in eight healthy volunteers and it is suggested that these data are consistent with the existence of a right fronto-parietal network for sustained, and possibly selective, attention, and a left frontospecific network for the phonological loop component of working memory.
574 citations
TL;DR: Brain imaging studies show that "holding something in mind" is associated with activity in an extended system which involves both prefrontal cortex and more posterior areas whose location is determined by the nature of the information being held in mind.
292 citations
TL;DR: The results support the presence of extra-motor neuronal involvement, particularly along a thalamo-frontal association pathway, in some non-demented ALS patients and suggest dysfunction of DLPFC in some ALS patients with associated cognitive impairments.
Abstract: PET measurements of regional cerebral blood flow (rCBF) were used to explore frontal lobe dysfunction in amyotrophic lateral sclerosis (ALS). An activation paradigm of executive frontal lobe function (verbal fluency), which contrasted rCBF during word generation and word repetition, was used. Two groups of ALS patients, defined by the presence or absence of cognitive impairment (ALSi) (impaired, n = 6: ALSu unimpaired, n = 6) were compared with healthy age-matched controls (n = 6). Patient selection was based on prior performance on a written test of verbal fluency. Additional neuropsychological assessment of the patients revealed evidence of executive and memory dysfunction in the ALSi group only, with marked deficits in tests of intrinsic generation. The ALSi patients displayed significantly (P < 0.001) impaired activation in cortical and subcortical regions including the dorsolateral prefrontal cortex (DLPFC; areas 46 and 9), lateral premotor cortex (areas 8 and 6), medial prefrontal and premotor cortices (areas 8 and 9), insular cortex bilaterally and the anterior thalamic nuclear complex. Although the three groups showed matched word generation performance on the scanning paradigm, the ALSu group displayed a relatively unimpaired pattern of activation. These results support the presence of extra-motor neuronal involvement, particularly along a thalamo-frontal association pathway, in some non-demented ALS patients. In addition, this study suggests dysfunction of DLPFC in some ALS patients with associated cognitive impairments.
276 citations
TL;DR: In this paper, the neural correlates of inner speech and of auditory verbal imagery were examined in normal volunteers, using positron emission tomography (PET) in order to examine the neural networks associated with these two tasks.
Abstract: The neural correlates of inner speech and of auditory verbal imagery were examined in normal volunteers, using positron emission tomography (PET). Subjects were shown single words which they used to generate short, stereotyped sentences without speaking. In an inner speech task, sentences were silently articulated, while in an auditory verbal imagery condition, subjects imagined sentences being spoken to them in an another person's voice. Inner speech was associated with increased activity in the left inferior frontal gyrus. Auditory verbal imagery was associated with increases in the same region, and in the left premotor cortex, the supplementary motor area and the left temporal cortex. The data suggest that the silent articulation of sentences involves activity in an area concerned with speech generation, while imagining speech is associated with additional activity in regions associated with speech perception.
261 citations
TL;DR: A positron emission tomography study designed to investigate the regional cerebral blood flow changes associated with topographical memory formation in humans, i.
Abstract: The importance of the hippocampal formation of the brain for allocentric spatial mapping of the environment has been suggested by animal lesion and electrophysiological work. Here we describe a positron emission tomography (PET) study designed to investigate the regional cerebral blood flow changes associated with topographical memory formation in humans, i.e. the formation of representations of large-scale environments necessary for way-finding. Topographical learning of an urban environment from viewing of film footage depicting navigation was associated with activation of the right parahippocampal gyrus and hippocampus, with activation also of the left parahippocampal gyrus. In addition, there was activity in the pretuneus. In contrast, the encoding of non-navigation episodic memory in a similar realworld context was not associated with activity in the hippocampal formation. Our results shed light on the neural basis of the human representation of large-scale space pinpointing a particular role for the human hippocampal formation in learning to find one's way.
232 citations
Journal Article•
TL;DR: An association between medial prefrontal activity and SITs is consistent with data linking this region to self-initiated thought, and its activation during tasks which entail thinking which is decoupled from stimuli in the immediate environment.
Abstract: The neural correlates of stimulus-independent thoughts (SITs) were investigated in two studies of normal volunteers, using positron emission tomography (PET) and H2(15)O to measure regional cerebral blood flow. Subjects rated how frequently SITs occurred while they were concurrently performing different sets of cognitive tasks. In both studies, the main positive correlations between SITs and blood flow were in the medial prefrontal region. These correlations were not attributable to between-task differences in cognitive demand, or to effects of practice on these demands. An association between medial prefrontal activity and SITs is consistent with data linking this region to self-initiated thought, and its activation during tasks which entail thinking which is decoupled from stimuli in the immediate environment.
TL;DR: Overall, in schizophrenic subjects the effect of apomorphine, which is interpreted in terms of a net dopaminergic antagonism, was to modify the brain activity, making the pattern more akin to that seen in control subjects.
Abstract: We used positron emission tomography (PET) to measure brain activity in healthy control subjects and unmedicated patients with schizophrenia. Subjects were scanned in the context of a combined psychological and pharmacological challenge, and we examined the effects of apomorphine, a drug acting on dopamine receptors, on brain systems engaged by a paced verbal fluency task. This factorial design enabled comparison of control subjects and schizophrenics in terms of the activations engendered by the cognitive task and the pharmacological challenge and the interaction of the two. We report a failure of cognitive task-related activation in anterior cingulate cortex and of task-related deactivation in the left superior temporal gyrus in the schizophrenic subjects. Compared with controls, the impaired cingulate activation was significantly reversed by apomorphine. Additionally, there was a trend for the abnormal fronto-temporal pattern of activation in schizophrenic subjects to be normalized by the drug. Overall, in schizophrenic subjects the effect of apomorphine, which we interpret in terms of a net dopaminergic antagonism, was to modify the brain activity, making the pattern more akin to that seen in control subjects. The results indicate both a regionally specific abnormality of brain function in schizophrenia and an abnormal pattern of fronto-temporal interactions.
TL;DR: This multivariate analysis may provide a statistical approach to PET activation studies that complements univariate approaches like statistical parametric mapping, and may facilitate the extension of existing multivariate techniques, like the scaled subprofile model and eigenimage analysis, to include hypothesis testing and statistical inference.
Abstract: In this paper we present a general multivariate approach to the analysis of functional imaging studies. This analysis uses standard multivariate techniques to make statistical inferences about activation effects and to describe the important features of these effects. More specifically, the proposed analysis uses multivariate analysis of covariance (ManCova) with Wilk's lambda to test for specific effects of interest (e.g., differences among activation conditions), and canonical variates analysis (CVA) to characterize differential responses in terms of distributed brain systems. The data are subject to ManCova after transformation using their principal components or eigenimages. After significance of the activation effect has been assessed, underlying changes are described in terms of canonical images. Canonical images are like eigenimages but take explicit account of the effects of error or noise. The generality of this approach is assured by the general linear model used in the ManCova. The design and inferences sought are embodied in the design matrix and can, in principle, accommodate most parametric statistical analyses. This multivariate analysis may provide a statistical approach to PET activation studies that 1) complements univariate approaches like statistical parametric mapping, and 2) may facilitate the extension of existing multivariate techniques, like the scaled subprofile model and eigenimage analysis, to include hypothesis testing and statistical inference.
TL;DR: It is proposed that hallucinations are experienced because patients have difficulty in distinguishing sensations caused by their own actions from those that arise from external influences, and this account needs to be extended to understand why patients experience the voices as emanating.
Abstract: Many patients with schizophrenia report hallucinations in which they hear voices talking to them or about them. Behavioural and physiological studies show that this experience is associated with processes occurring in auditory language systems associated with both the production and the reception of speech. I propose that hallucinations are experienced because patients have difficulty in distinguishing sensations caused by their own actions from those that arise from external influences. This distinction can be made by predicting the sensations that will result from executive commands (forward modelling). If the predicted sensation matches the actual sensation then no outside influences have occurred and perception of change can be 'cancelled'. At the physiological level this mechanism depends upon interactions between the prefrontal areas where the executive commands originate and posterior brain regions concerned with the resultant sensations. Evidence from functional brain imaging confirms that interactions between prefrontal (executive) areas and auditory association areas are abnormal in schizophrenia. However, this account needs to be extended before we can understand why patients experience the voices as emanating, not just from an external source, but from agents who are trying to influence their behaviour. Recent imaging studies suggest that medial prefrontal cortex is engaged when we think about other people, but the precise nature of the interaction of this brain area with other regions remains to be established.
TL;DR: In this article, the EEG evoked response to tones (N100/Nd response) is strongly modulated by attention and arises in auditory cortex and adjacent areas was strongly correlated with rate of tone presentation, but this relationship was not affected by the direction of attention.
TL;DR: The amount of confabulation was found to be related to difficulties in suppressing inappropriate responses and formal thought disorder, but unrelated to understanding of the gist or moral of the narratives.
Abstract: This study is an attempt to demonstrate confabulation in schizophrenia. Twelve patients who met DSM-III-R criteria for schizophrenia were matched for age, sex and pre-morbid IQ with 12 volunteers, 9 of whom were normal healthy subjects, with the remainder being depressed patients. To elicit confabulation, subjects were asked to recall narratives. In addition, subjects were examined on a number of neuropsychological tests. Confabulation was defined as recall of information not present in the narrative. Variable amounts of confabulation were observed in all schizophrenics, while only one control subject confabulated. The content and structure of their productions differed from previously reported forms of confabulation in that schizophrenic patients spontaneously rearranged the original narratives to produce new ideas. The amount of confabulation was found to be related to difficulties in suppressing inappropriate responses (Hayling test) and formal thought disorder, but unrelated to understanding of the gist or moral of the narratives. Tentative mechanisms for the process of confabulation are proposed, based on specific difficulties with comprehension, response monitoring and response suppression.
TL;DR: Brain imaging reveals that, in dyslexics, the visual-motion area of the brain fails to activate, which may be a marker for a deviation in brain function which remained largely invisible until complex writing systems evolved.
Abstract: Brain imaging reveals that, in dyslexics, the visual-motion area of the brain fails to activate. This failure may be a marker for a deviation in brain function which remained largely invisible until complex writing systems evolved.
TL;DR: It can be argued that human communication works so well largely because the authors all have a ’theory of mind’, which implies that what people will do can best be predicted from their intentions, their knowledge and their beliefs.
Abstract: It can be argued that human communication works so well largely because we all have a ’theory of mind’. We assume that other peoples’ behaviour, as well as our own, is determined by their mental states. In other words, what people will do can best be predicted from their intentions, their knowledge and their beliefs. Dennett (1987) has referred to this approach for understanding other people as ’having an intentional stance’. The causal role of mental states is most strikingly apparent in the case of false beliefs, since actions based on such beliefs are clearly independent of the real state of the world. For example, Romeo kills himself because he believes, falsely, that Juliet is dead. Errors this extreme may be rare in normal circum-
TL;DR: A detailed investigation of three cases who were previously identified as confabulators found that the severity of cognitive impairment reflects the severityof confabulation, but that memory impairment is neither necessary nor sufficient to account for confabulations.
Abstract: Confabulation is a newly described abnormality in schizophrenia, but its mechanisms are as yet unclear. Here we describe a detailed investigation of three cases who were previously identified as confabulators. The patients were administered experimental tasks as well as standard neuropsychological tests of memory and executive function in an attempt to elucidate the possible mechanisms. It was found that the severity of cognitive impairment reflects the severity of confabulation, but that memory impairment is neither necessary nor sufficient to account for confabulation. This suggests that confabulation and memory have different substrates. Within the spectrum of executive deficits, impairments in response suppression and response monitoring, but not planning or generation, were consistently associated with confabulation. It is suggested that the stages of this form of confabulation are unlike those previously reported in other patients since faults occur at both input and output. At the input st...
01 Jan 1996
TL;DR: PET measurements of regional cerebral blood flow support the presence of extra-motor neuronal involvement, particularly along a thalamo-frontal association pathway, in some non-demented ALS patients and suggest dysfunction of DLPFC in some ALS patients with associated cognitive impairments.
Abstract: Summary PET measurements of regional cerebral blood flow (rCBF) were used to explore frontal lobe dysfunction in amyotrophic lateral sclerosis (ALS). An activation paradigm of executive frontal lobe function (verbal fluency), which contrasted rCBF during word generation and word repetition, was used. Two groups of ALS patients, defined by the presence or absence of cognitive impairment (ALSi) (impaired, n = 6; ALSu, unimpaired, n = 6) were compared with healthy age-matched controls (n = 6). Patient selection was based on prior performance on a written test of verbal fluency. Additional neuropsychological assessment of the patients revealed evidence of executive and memory dysfunction in the ALSi group only, with marked deficits in tests of intrinsic generation. The ALSi patients displayed significantly (P < 0.001) impaired activation in cortical and subcortical regions including the dorsolateral prefrontal cortex (DLPFC; areas 46 and 9), lateral premotor cortex (areas 8 and 6), medial prefrontal and premotor cortices (areas 8 and 9), insular cortex bilaterally and the anterior thalamic nuclear complex. Although the three groups showed matched word generation performance on the scanning paradigm, the ALSu group displayed a relatively unimpaired pattern of activation. These results support the presence of extra-motor neuronal involvement, particularly along a thalamo-frontal association pathway, in some non-demented ALS patients. In addition, this study suggests dysfunction of DLPFC in some ALS patients with associated cognitive impairments.