Biomedical subjects

Edward T Bullmore

Publications and source records attributed to Edward T Bullmore.

At least 19 recordsLinked to original sources

PubMed2006

Emotional memory in depersonalization disorder: a functional MRI study.

This study examines emotional memory effects in primary depersonalization disorder (DPD). A core complaint of DPD sufferers is the dulling of emotional responses, and previous work has shown that, in response to aversive stimuli, DPD patients do not show activation of brain regions involved in normal emotional processing. We hypothesized that DPD sufferers would not show the normal emotional enhancement of memory, and that they would not show activation of brain regions concerned with emotional processing during encoding and recognition of emotional verbal material. Using fMRI, 10 DPD patients were compared with an age-matched healthy control group while performing a test of emotional verbal memory, comprising one encoding and two recognition memory tasks. DPD patients showed significantly enhanced recognition for overtly emotive words, but did not show enhancement of memory for neutral words encoded in an emotive context. In addition, patients did not show activation of emotional processing areas during encoding, and exhibited no substantial difference in their neural responses to emotional and neutral material in the encoding and emotional word recognition tasks. This study provides further evidence that patients with DPD do not process emotionally salient material in the same way as healthy controls, in accordance with their subjective descriptions of reduced or absent emotional responses.

Adult↗

PubMed2006

The relationship between motor deficit and hemisphere activation balance after stroke: A 3T fMRI study.

Functional imaging during movement of the hand affected by a stroke has shown excess activation of the contralesional motor network, implying less physiological hemisphere activation balance. Although this may be adaptive, the relationship between the severity of motor deficit and the hemisphere activation balance for the four major cortical motor areas has not been systematically studied. We prospectively studied 19 right-handed patients with first-ever stroke (age range 61+/-10 years) in the stable phase of recovery (>3 months after onset), using auditory-paced index-thumb (IT) tapping of the affected hand at 1.25 Hz as the fMRI paradigm. The hemisphere activation balance for the primary motor (M1), primary somatosensory (S1), supplementary motor (SMA) and dorsal premotor (PMd) areas was measured by a modified weighted laterality index (wLI), and correlations with motor performance (assessed by the affected/unaffected ratio of maximum IT taps in 15 s, termed IT-R) were computed. There were statistically significant negative correlations between IT-R and the wLI for M1 and S1, such that the more the hemispheric balance shifted contralesionally, the worse the performance. Furthermore, worse performance was related to a greater amount of contralesional, but not ipsilesional, activation. No significant correlation between IT-R and the wLI was obtained for the SMA and PMd, which functionally have stronger bilateral organization. These findings suggest that the degree of recovery of fine finger motion after stroke is determined by the extent to which activation balance in the primary sensory motor areas--where most corticospinal fibers originate--departs from normality. This observation may have implications for therapy.

Aged↗

PubMed2006

Fronto-cerebellar systems are associated with infant motor and adult executive functions in healthy adults but not in schizophrenia.

Delineating longitudinal relationships between early developmental markers, adult cognitive function, and adult brain structure could clarify the pathogenesis of neurodevelopmental disorders such as schizophrenia. We aimed to identify brain structural correlates of infant motor development (IMD) and adult executive function in nonpsychotic adults and to test for abnormal associations between these measures in people with schizophrenia. Representative samples of nonpsychotic adults (n = 93) and people with schizophrenia (n = 49) were drawn from the Northern Finland 1966 general population birth cohort. IMD was prospectively assessed at age 1 year; executive function testing and MRI were completed at age 33-35 years. We found that earlier motor development in infancy was correlated with superior executive function in nonpsychotic subjects. Earlier motor development was also normally associated with increased gray matter density in adult premotor cortex, striatum, and cerebellum and increased white matter density in frontal and parietal lobes. Adult executive function was normally associated with increased gray matter density in a fronto-cerebellar system that partially overlapped, but was not identical to, the gray matter regions normally associated with IMD. People with schizophrenia had relatively delayed IMD and impaired adult executive function in adulthood. Furthermore, they demonstrated no normative associations between fronto-cerebellar structure, IMD, or executive function. We conclude that frontal cortico-cerebellar systems correlated with adult executive function are anatomically related to systems associated with normal infant motor development. Disruption of this anatomical system may underlie both the early developmental and adult cognitive abnormalities in schizophrenia.

Adult↗

PubMed2006

Differential activation of the amygdala and the 'social brain' during fearful face-processing in Asperger Syndrome.

Impaired social cognition is a core feature of autism. There is much evidence showing people with autism use a different cognitive style than controls for face-processing. We tested if people with autism would show differential activation of social brain areas during a face-processing task. Thirteen adults with high-functioning autism or Asperger Syndrome (HFA/AS) and 13 matched controls. We used fMRI to investigate 'social brain' activity during perception of fearful faces. We employed stimuli known to reliably activate the amygdala and other social brain areas, and ROI analyses to investigate brain areas responding to facial threat as well as those showing a linear response to varying threat intensities. We predicted: (1) the HFA/AS group would show differential activation (as opposed to merely deficits) of the social brain compared to controls and (2) that social brain areas would respond to varied intensity of fear in the control group, but not the HFA/AS group. Both predictions were confirmed. The controls showed greater activation in the left amygdala and left orbito-frontal cortex, while the HFA/AS group showed greater activation in the anterior cingulate gyrus and superior temporal cortex. The control group also showed varying responses in social brain areas to varying intensities of fearful expression, including differential activations in the left and right amygdala. This response in the social brain was absent in the HFA/AS group. HFA/AS are associated with different patterns of activation of social brain areas during fearful emotion processing, and the absence in the HFA/AS brain of a response to varying emotional intensity.

Adult↗

PubMed2006

Task-induced deactivations during successful paired associates learning: an effect of age but not Alzheimer's disease.

Task-induced fMRI deactivations during successful encoding and retrieval of visuospatial paired associates were examined at different levels of task difficulty in younger and older adults (Experiment 1), and older adults with and without mild probable Alzheimer's disease (AD) (Experiment 2). Irrespective of the level of task difficulty, common deactivations (determined through the use of conjunction analyses) were observed in the lateral and medial prefrontal, anterior and posterior cingulate, and temporal brain regions and in the claustrum during both encoding and retrieval in younger and older adults (Experiment 1). In AD patients and healthy older adults, common deactivations were found in posterior cingulate, temporal, and lateral parietal regions and in the insula and claustrum during encoding and retrieval of paired associates (Experiment 2). As task difficulty increased, irrespective of the type of task, the magnitude of task-induced deactivations increased in the medial prefrontal/superior frontal gyrus and middle/posterior cingulate cortex in younger and older adults (Experiment 1), and in the middle cingulate cortex in older adults with and without AD (Experiment 2). In Experiment 1, greater deactivation was observed in the anterior cingulate gyrus in older compared to younger adults during retrieval of paired associates which was attributed to greater suppression of task-unrelated thoughts in the older group. No significant differences in task-induced deactivation, or in the type of relationship exhibited between deactivation and task difficulty, were observed between older adults with and without AD (Experiment 2). It was suggested that this was related to the matching of successful task performance and task difficulty across patient and control groups. Following previous proposals, task-induced deactivations were suggested to underlie a shifting of attentional focus from monitoring of the self and the environment (through attenuation of these activities) to external, goal-directed behaviour.

Adult↗

PubMed2006

Frontal responses during learning predict vulnerability to the psychotogenic effects of ketamine: linking cognition, brain activity, and psychosis.

CONTEXT: Establishing a neurobiological account of delusion formation that links cognitive processes, brain activity, and symptoms is important to furthering our understanding of psychosis. OBJECTIVE: To explore a theoretical model of delusion formation that implicates prediction error-dependent associative learning processes in a pharmacological functional magnetic resonance imaging study using the psychotomimetic drug ketamine. DESIGN: Within-subject, randomized, placebo-controlled study. SETTING: Hospital-based clinical research facility, Addenbrooke's Hospital, Cambridge, England. The work was completed within the Wellcome Trust and Medical Research Council Behavioral and Clinical Neuroscience Institute, Cambridge. PARTICIPANTS: Fifteen healthy, right-handed volunteers (8 of whom were male) with a mean +/- SD age of 29 +/- 7 years and a mean +/- SD predicted full-scale IQ of 113 +/- 4 were recruited from within the local community by advertisement. INTERVENTIONS: Subjects were given low-dose ketamine (100 ng/mL of plasma) or placebo while performing a causal associative learning task during functional magnetic resonance imaging. In a separate session outside the scanner, the dose was increased (to 200 ng/mL of plasma) and subjects underwent a structured clinical interview. MAIN OUTCOME MEASURES: Brain activation, blood plasma levels of ketamine, and scores from psychiatric ratings scales (Brief Psychiatric Ratings Scale, Present State Examination, and Clinician-Administered Dissociative States Scale). RESULTS: Low-dose ketamine perturbs error-dependent learning activity in the right frontal cortex (P = .03). High-dose ketamine produces perceptual aberrations (P = .01) and delusion-like beliefs (P = .007). Critically, subjects showing the highest degree of frontal activation with placebo show the greatest occurrence of drug-induced perceptual aberrations (P = .03) and ideas or delusions of reference (P = .04). CONCLUSIONS: These findings relate aberrant prediction error-dependent associative learning to referential ideas and delusions via a perturbation of frontal cortical function. They are consistent with a model of delusion formation positing disruptions in error-dependent learning.

Adult↗

PubMed2006

Permutation testing of orthogonal factorial effects in a language-processing experiment using fMRI.

The block-paradigm of the Functional Image Analysis Contest (FIAC) dataset was analysed with the Brain Activation and Morphological Mapping software. Permutation methods in the wavelet domain were used for inference on cluster-based test statistics of orthogonal contrasts relevant to the factorial design of the study, namely: the average response across all active blocks, the main effect of speaker, the main effect of sentence, and the interaction between sentence and speaker. Extensive activation was seen with all these contrasts. In particular, different vs. same-speaker blocks produced elevated activation in bilateral regions of the superior temporal lobe and repetition suppression for linguistic materials (same vs. different-sentence blocks) in left inferior frontal regions. These are regions previously reported in the literature. Additional regions were detected in this study, perhaps due to the enhanced sensitivity of the methodology. Within-block sentence suppression was tested post-hoc by regression of an exponential decay model onto the extracted time series from the left inferior frontal gyrus, but no strong evidence of such an effect was found. The significance levels set for the activation maps are P-values at which we expect <1 false-positive cluster per image. Nominal type I error control was verified by empirical testing of a test statistic corresponding to a randomly ordered design matrix. The small size of the BOLD effect necessitates sensitive methods of detection of brain activation. Permutation methods permit the necessary flexibility to develop novel test statistics to meet this challenge.

Algorithms↗

PubMed2006

Applications of fMRI in translational medicine and clinical practice.

Functional MRI (fMRI) has had a major impact in cognitive neuroscience. fMRI now has a small but growing role in clinical neuroimaging, with initial applications to neurosurgical planning. Current clinical research has emphasized novel concepts for clinicians, such as the role of plasticity in recovery and the maintenance of brain functions in a broad range of diseases. There is a wider potential for clinical fMRI in applications ranging from presymptomatic diagnosis, through drug development and individualization of therapies, to understanding functional brain disorders. Realization of this potential will require changes in the way clinical neuroimaging services are planned and delivered.

Animals↗

PubMed2006

Regional brain morphometry in patients with schizophrenia or bipolar disorder and their unaffected relatives.

OBJECTIVE: Schizophrenia and psychotic bipolar disorder have a number of overlapping symptoms and risk factors, but it is not yet clear if the disorders are characterized by similar deviations in brain morphometry or whether any such deviations reflect the impact of shared susceptibility genes on brain structure. The authors used region-of-interest morphometry to volumetrically assess brain structures frequently implicated in psychotic illness in families affected with schizophrenia or psychotic bipolar disorder. METHOD: Magnetic resonance imaging brain scans were obtained from 243 subjects, comprising 42 patients with schizophrenia or schizoaffective disorder, 57 of their unaffected first-degree relatives, 38 patients with psychotic bipolar disorder, 52 of their unaffected first-degree relatives, and 54 healthy comparison subjects. Most of the families affected with schizophrenia and all of the families affected with bipolar disorder were multiply affected with the illness. Volumetric measurements of the cerebrum, lateral ventricles, third ventricle, and hippocampus were completed with stereological methods. RESULTS: Patients with schizophrenia had increased volume of the lateral and third ventricles and reduced hippocampal volume. None of these volumetric abnormalities was present in psychotic bipolar disorder. Unaffected relatives of patients with schizophrenia from multiply affected families had enlarged lateral ventricles but no other volumetric deviations. Unaffected relatives of patients with bipolar disorder showed preservation of ventricular and hippocampal volume. CONCLUSIONS: Schizophrenia and psychotic bipolar disorder are characterized by morphometric distinctions in ventricular and hippocampal regions. Lateral ventricular enlargement represents a potential morphometric endophenotype for schizophrenia.

Adolescent↗

PubMed2005

Modulation of effective connectivity by cognitive demand in phonological verbal fluency.

Verbal fluency is a classic neuropsychological measure of language production. Phonological verbal fluency involves the generation of words beginning with a specified letter, and its functional neuroanatomy is comprised of a distributed network of regions which is modulated by cognitive load. In order to investigate the functional relationship of these regions, the effective connectivity was analyzed with covariance structural equation modeling under conditions of varying cognitive load. Significant path coefficients were evident between the anterior cingulate, left middle frontal gyrus, and precuneus. The left middle frontal gyrus showed a facilitory projection to the precuneus which had a suppressive influence on anterior cingulate activation. With increasing cognitive demand, the left middle frontal projection to the precuneus became suppressive, and the path coefficient from the precuneus to the anterior cingulate showed a marked diminution in strength. The path analysis suggests that the lead-in process for letter verbal fluency may primarily involve an orthographic visual strategy. The marked changes in path coefficients with the increased cognitive load may reflect the greater demands placed on executive function. The significant changes in path coefficient values with increased cognitive demand indicate the importance of accounting for task difficulty not only in the interpretation of brain activation maps but also for effective connectivity measurements.

Adult↗

PubMed2005

Impairment of specific episodic memory processes by sub-psychotic doses of ketamine: the effects of levels of processing at encoding and of the subsequent retrieval task.

RATIONALE: The precise nature of the impact of the N-methyl-D-aspartate antagonist, ketamine, upon human episodic memory, has yet to be elucidated fully. OBJECTIVES: This study sought to assess the effects of ketamine on the sub-processes facilitating memory encoding and retrieval. METHODS: We evaluated the effects of the drug on a series of memory performance measures depending upon whether it was administered at the encoding or retrieval stage and on the nature of the encoding task used. Twelve healthy volunteers participated in a double-blind, placebo-controlled, randomized, within-subjects study. Intravenous infusions of placebo, 50 ng/ml ketamine or 100 ng/ml ketamine were administered. We investigated the effects of ketamine on three key aspects of episodic memory: encoding vs retrieval processes, source memory, and depth of processing. Data were analysed using both multinomial modelling and standard measures of item discrimination and response bias. RESULTS: Deleterious effects of ketamine on episodic memory were primarily attributable to its effects on encoding, rather than retrieval processes. Recognition memory was impaired for items encoded at an intermediate level of processing, but preserved for shallowly and deeply encoded items. Increased source guessing bias was also observed when encoding took place under ketamine. CONCLUSIONS: The effects of ketamine upon episodic memory seem, therefore, to predominate at encoding. Furthermore, our results are also consistent with a specific impairment of encoding processes that result in subsequent recollective, as opposed to familiarity-based, retrieval. The observed effects are compatible with memory deficits seen in schizophrenia and thus provide some support for the ketamine model of the disease.

Adolescent↗

PubMed2005

Functional dysconnectivity in schizophrenia associated with attentional modulation of motor function.

It is not known whether there is a core abnormality that occurs in all cases of schizophrenia. The cognitive dysmetria hypothesis proposes that there is such an abnormality which is characterized cognitively by a disruption in control and coordination processes, and functionally by abnormal inter-regional connectivity within the cortico-cerebellar-thalamo-cortical circuit (CCTCC). In the current study, we used functional MRI (fMRI) to investigate these two key aspects of the hypothesis. Since patients with schizophrenia show deficits in attention which have been characterized extensively using the continuous performance task (CPT) and since functional imaging studies have also demonstrated that this task engages the CCTCC, we used this task to investigate whether two patient groups with distinct symptom profiles would show functional dysconnectivity within this network. Three groups of subjects participated in the study: healthy volunteers (n = 12), schizophrenia patients with both negative and positive symptoms (n = 11) and schizophrenia patients with primarily positive symptoms (n = 11). Patient groups were matched for age of illness onset and medication, and to the control group for age, gender and handedness. Subjects were scanned using fMRI whilst they performed a modified version of the CPT, involving both degraded and non-degraded stimuli. Stimulus degradation has been shown to produce decrements in sensitivity, which is thought to reflect increased demands on the limited capacity of visual attention. Between-group comparisons revealed that patients with schizophrenia, irrespective of symptomatology, showed attenuation of the anterior cingulate and cerebellar response to stimulus degradation in comparison with control subjects. We also observed disruptions of inter-regional brain integration in schizophrenia. A task-specific relationship between the medial superior frontal gyrus and both anterior cingulate and the cerebellum was disrupted in both patient groups in comparison with controls. In addition, patients with negative symptoms showed impaired behavioural performance, and abnormal task-related connectivity between anterior cingulate and supplementary motor area. These findings are consistent with theoretical accounts of schizophrenia as a disorder of functional integration, and with the cognitive dysmetria hypothesis, which posits a disconnection within the CCTCC as a fundamental abnormality in schizophrenia, independent of diagnostic subtype. Furthermore, these data show evidence of additional functional deficits in patients with negative symptoms, deficits which may explain the accompanying attentional impairment.

Adult↗

PubMed2005

Change detection in children with autism: an auditory event-related fMRI study.

Autism involves impairments in communication and social interaction, as well as high levels of repetitive, stereotypic, and ritualistic behaviours, and extreme resistance to change. This latter dimension, whilst required for a diagnosis, has received less research attention. We hypothesise that this extreme resistance to change in autism is rooted in atypical processing of unexpected stimuli. We tested this using auditory event-related fMRI to determine regional brain activity associated with passive detection of infrequently occurring frequency-deviant and complex novel sounds in a no-task condition. Participants were twelve 10- to 15-year-old children with autism and a group of 12 age- and sex-matched healthy controls. During deviance detection, significant activation common to both groups was located in the superior temporal and inferior frontal gyri. During 'novelty detection', both groups showed activity in the superior temporal gyrus, the temporo-parietal junction, the superior and inferior frontal gyri, and the cingulate gyrus. Children with autism showed reduced activation of the left anterior cingulate cortex during both deviance and novelty detection. During novelty detection, children with autism also showed reduced activation in the bilateral temporo-parietal region and in the right inferior and middle frontal areas. This study confirms previous evidence from ERP studies of atypical brain function related to automatic change detection in autism. Abnormalities involved a cortical network known to have a role in attention switching and attentional resource distribution. These results throw light on the neurophysiological processes underlying autistic 'resistance to change'.

Acoustic Stimulation↗

PubMed2005

Emotional memory: separating content and context.

It is now well established that emotion enhances episodic memory. However, it remains unclear whether the same neural processes underlie enhancement of memory for both emotional stimuli and neutral stimuli encoded in an emotive context. We designed an experiment that specifically attempted to separate these effects and that was validated on 30 participants. We then used functional magnetic resonance imaging (fMRI) to examine the neural correlates of encoding and retrieval of the two classes of stimuli in 12 healthy male volunteers. We predicted that aversive emotional context would enhance memory regardless of content and that activation of anterior cingulate would be inversely related to retrieval of aversive items. Both predictions were supported. Furthermore we demonstrated apparent asymmetrical lateralisation of activation in the hippocampal/parahippocampal complex during recognition of words from aversive sentences: more left-sided activation for neutral words from aversive contexts, and more right-sided activation for aversive content words. These findings, if applicable to the wider population, may have application in a range of psychiatric disorders where interactions between emotion and cognition are relevant.

Adolescent↗

PubMed2005

Visuospatial learning and executive function are independently impaired in first-episode psychosis.

BACKGROUND: Demonstrating specific cognitive impairments in psychotic disorders is difficult. However, specific deficits in memory and executive functions have often been claimed. The Cambridge Neuropsychological Test Automated Battery (CANTAB) tasks of IDED attention-shifting (an executive task) and visuospatial paired associates learning (PAL, a memory task) require intact frontal and temporo-hippocampal functioning, respectively; both have been suggested as markers of disease progress in psychosis. METHOD: Seventy-one subjects with a first-episode psychosis or at-risk mental state were assessed on these two tasks during referral to a specialist service, the Cambridge-based CAMEO early intervention team. RESULTS: Performance on the two tasks was dissociated. Poor performance on the PAL test was associated with increased symptom levels and poorer global function, while failure on the IDED executive test was not found to have significant clinical associations. Duration of illness was not associated with performance on either task. CONCLUSIONS: Visuospatial PAL failure may be a marker of clinical severity at the onset of psychosis while IDED performance may reflect a more stable, trait-like impairment. Dissociated performance on the executive and associative learning tasks may reflect independent, neurally dissociated impairments that do not arise in a fixed order. This may explain some of the heterogeneity of cognitive function seen in early psychosis.

Adult↗

PubMed2005

Brain response to visceral aversive conditioning: a functional magnetic resonance imaging study.

BACKGROUND & AIMS: Brain-imaging studies to date have confounded visceral pain perception with anticipation. We used functional magnetic resonance imaging of the human brain to study the neuroanatomic network involved in aversive conditioning of visceral pain and, thus, anticipation. METHODS: Eight healthy volunteers (5 male) participated in the study. We used a classic conditioning paradigm in which 3 neutral stimuli (differently colored circles) that acted as conditioned stimuli were paired with painful esophageal distention, air puff to the wrist, or nothing, which acted as unconditioned stimuli. Neural activity was measured during learning, anticipation (pairing only 50% of conditioned stimuli with their unconditioned stimuli), and extinction (unpaired conditioned stimuli) phases. For magnetic resonance imaging, axial slices depicting blood oxygen level-dependent contrast were acquired with a 1.5-T system. RESULTS: Neural responses during the learning phase included areas commonly associated with visceral pain (anterior cingulate cortex, insula, and primary and secondary somatosensory cortices) and innocuous somatosensory perception (primary and secondary somatosensory cortices and insula). During the anticipation and extinction phases of aversive stimulation, brain activity resembled that seen during actual painful esophageal stimulation. In contrast, anticipation and extinction of the innocuous somatic stimulus failed to show that effect. CONCLUSIONS: We have shown that actual and anticipated visceral pain elicit similar cortical responses. These results have implications for the design and interpretation of brain-imaging studies of visceral pain. They not only contribute to our understanding of the processing of visceral pain, but also have clinical implications for the management of chronic pain states.

Adult↗

PubMed2005

Functional neuroanatomy of successful paired associate learning in Alzheimer's disease.

OBJECTIVE: The purpose of the study was to develop a strategy for functional imaging of neurodegenerative disorders that overcomes confounds associated with differential performance between patient and comparison groups. METHOD: Functional magnetic resonance imaging was used to examine responses to increasing difficulty of visuospatial paired associate learning in 12 patients with mild probable Alzheimer's disease and 12 age-matched healthy comparison subjects. Performance was matched across groups by only examining successful encoding and retrieval attempts. Adjustment for task difficulty was made on an individual basis so that the patients with Alzheimer's disease and the comparison subjects performed at the same relative levels of difficulty. RESULTS: A network of lateral and medial frontoparietal and occipital regions was engaged in all subjects during successful associative learning. As task difficulty increased, blood-oxygen-level-dependent responses increased linearly in occipitoparietal regions during encoding and retrieval. Differential activations in patients with Alzheimer's disease and comparison subjects were small and were found only when an uncorrected statistical threshold was used. CONCLUSIONS: By controlling for confounds of varying task difficulty and subsequent performance, remarkably similar brain activations were identified during successful paired associate learning in patients with Alzheimer's disease and in healthy comparison subjects. The study methods provide a useful model for further applications of functional imaging involving cognitive activation paradigms in the study of neuropsychiatric disorders.

Aged↗

PubMed2004

Prediction error during retrospective revaluation of causal associations in humans: fMRI evidence in favor of an associative model of learning.

Associative learning theory assumes that prediction error is a driving force in learning. A competing view, probabilistic contrast (PC) theory, is that learning and prediction error are unrelated. We tested a learning phenomenon that has proved troublesome for associative theory--retrospective revaluation--to evaluate these two models. We previously showed that activation in right lateral prefrontal cortex (PFC) provides a reliable signature for the presence of prediction error. Thus, if the associative view is correct, retrospective revaluation should be accompanied by right lateral PFC activation. PC theory would be supported by the absence of this activation. Right PFC and ventral striatal activation occurred during retrospective revaluation, supporting the associative account. Activations appeared to reflect the degree of revaluation, predicting later brain responses to revalued cues. Our results support a modified associative account of retrospective revaluation and demonstrate the potential of functional neuroimaging as a tool for evaluating competing learning models.

Adult↗