A systematic review and quantitative appraisal of fMRI studies of verbal fluency: role of the left inferior frontal gyrus.

The left inferior frontal gyrus (LIFG) has consistently been associated with both phonologic and semantic operations in functional neuroimaging studies. Two main theories have proposed a different functional organization in the LIFG for these processes. One theory suggests an anatomic parcellation of phonologic and semantic operations within the LIFG.

fMRI of parents of children with Asperger Syndrome: a pilot study.

Background: People with autism or Asperger Syndrome (AS) show altered patterns of brain activity during visual search and emotion recognition tasks. Autism and AS are genetic conditions and parents may show the 'broader autism phenotype.'

Aims: (1) To test if parents of children with AS show atypical brain activity during a visual search and an empathy task; (2) to test for sex differences during these tasks at the neural level; (3) to test if parents of children with autism are hyper-masculinized, as might be predicted by the 'extreme male brain' theory.

Cerebral processing of food-related stimuli: effects of fasting and gender.

To maintain nutritional homeostasis, external food-related stimuli have to be evaluated in relation to the internal states of hunger or satiety. To examine the neural circuitry responsible for integration of internal and external determinants of human eating behaviour, brain responses to visual and complex gustatory food-related stimuli were measured using functional magnetic resonance imaging in 18 healthy non-smokers (10 women, 8 men). Each individual was studied on two occasions, the order of which was counterbalanced; after eating as usual and after 24 h fasting.

A method to produce evolving functional connectivity maps during the course of an fMRI experiment using wavelet-based time-varying Granger causality.

Functional magnetic resonance imaging (fMRI) is widely used to identify neural correlates of cognitive tasks. However, the analysis of functional connectivity is crucial to understanding neural dynamics. Although many studies of cerebral circuitry have revealed adaptative behavior, which can change during the course of the experiment, most of contemporary connectivity studies are based on correlational analysis or structural equations analysis, assuming a time-invariant connectivity structure.

Variable precision registration via wavelets: optimal spatial scales for inter-subject registration of functional MRI.

The detection of significantly activated brain regions in multi-subject functional magnetic resonance imaging (fMRI) studies almost invariably entails the coregistration of individual subjects' data in a standard space. Here, we investigate how sensitivity to detect loci of generic activation in such studies may be conditioned by the precision of anatomical registration. We describe a novel algorithm, implemented in the wavelet domain, for inhomogeneous deformation of individual images to match a template.

Stroop performance in bipolar disorder: further evidence for abnormalities in the ventral prefrontal cortex.

Objectives: Bipolar patients are impaired in Stroop task performance, a measure of selective attention. Structural and functional abnormalities in task-associated regions, in particular the prefrontal cortex (PFC), have been reported in this population. We aimed to examine the relationship between functional abnormalities, impaired task performance and the severity of depressive symptoms in bipolar patients.

The role of 'shared representations' in social perception and empathy: an fMRI study.

Evidence suggests that we use the same mechanisms for both producing and perceiving actions. Such 'shared representations' may also underlie social perception and empathy. However, this idea raises some important and as yet unresolved questions: (i) how do we distinguish other-orientated empathic responses from a self-orientated reactions such as personal distress and (ii) what are the neural substrates underpinning these processes? We employed event-related functional magnetic resonance imaging (fMRI) to explore whether 'shared representations' were recruited to decode dynamic social stimuli in 12 healthy volunteers.

Human attachment security is mediated by the amygdala: evidence from combined fMRI and psychophysiological measures.

The neural basis of human attachment security remains unexamined. Using event-related functional magnetic resonance imaging (fMRI) and simultaneous recordings of skin conductance levels, we measured neural and autonomic responses in healthy adult individuals during a semantic conceptual priming task measuring human attachment security "by proxy". Performance during a stress but not a neutral prime condition was associated with response in bilateral amygdalae.

An fMRI study of verbal self-monitoring: neural correlates of auditory verbal feedback.

The ability to recognize one's own inner speech is essential for a sense of self. The verbal self-monitoring model proposes that this process entails a communication from neural regions involved in speech production to areas of speech perception. According to the model, if the expected verbal feedback matches the perceived feedback, then there would be no change in activation in the lateral temporal cortices.

Deriving meaning: Distinct neural mechanisms for metaphoric, literal, and non-meaningful sentences.

In this study, we used a novel cognitive paradigm and event-related functional magnetic resonance imaging (ER-fMRI) to investigate the neural substrates involved in processing three different types of sentences. Participants read either metaphoric (Some surgeons are butchers), literal (Some surgeons are fathers), or non-meaningful sentences (Some surgeons are shelves) and had to decide whether they made sense or not. We demonstrate that processing of the different sentence types relied on distinct neural mechanisms.

Functional neuroanatomy of body shape perception in healthy and eating-disordered women.

Background: Abnormalities in perception and evaluation of body shape are a hallmark of eating disorders.

Methods: Brain responses to line drawings of underweight, normal weight, and overweight female bodies were measured with functional magnetic resonance imaging in 9 women with bulimia nervosa, 13 with anorexia nervosa, and 18 healthy women. Participants rated the stimuli for fear and disgust.

The neural correlates of anhedonia in major depressive disorder.

Background: Anhedonia is a relative lack of pleasure in response to formerly rewarding stimuli. It is an important diagnostic feature of major depressive disorder (MDD), and predicts antidepressant efficacy. Understanding its neurobiological basis may help to target new treatments and predict treatment outcomes.

A double dissociation of ventromedial prefrontal cortical responses to sad and happy stimuli in depressed and healthy individuals.

Background: The ventromedial prefrontal cortex (VMPFC) is a region implicated in the assessment of the rewarding potential of stimuli and may be dysfunctional in major depressive disorder (MDD). The few studies examining prefrontal cortical responses to emotive stimuli in MDD have indicated increased VMPFC responses to pleasant images but decreased responses to sad mood provocation when compared with healthy individuals. We wished to corroborate these results by examining neural responses to personally relevant happy and sad stimuli in MDD and healthy individuals within the same paradigm.

Lexical and sentential processing in British Sign Language.

Studies of spoken and written language suggest that the perception of sentences engages the left anterior and posterior temporal cortex and the left inferior frontal gyrus to a greater extent than non-sententially structured material, such as word lists. This study sought to determine whether the same is true when the language is gestural and perceived visually. Regional neural activity was measured using functional MRI while Deaf and hearing native signers of British Sign Language (BSL) detected semantic anomalies in well-formed BSL sentences and when they detected nonsense signs in lists of unconnected BSL signs.

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.

Abnormal brain activation during inhibition and error detection in medication-naive adolescents with ADHD.

Objective: Patients with attention deficit hyperactivity disorder (ADHD) and a medication history have shown abnormal brain activation in prefrontal and striatal brain regions during cognitive challenge. Previous findings have been confounded, however, by potential long-term effects of stimulant medication exposure and group discrepancies in task performance. The aim of this study was to investigate whether medication-naive adolescents with ADHD would still show abnormal brain activation in prefrontal brain regions during motor response inhibition in a task designed to control for intergroup performance discrepancies.

Tryptophan depletion reduces right inferior prefrontal activation during response inhibition in fast, event-related fMRI.

Rationale And Objective: In animal and human studies, the neurotransmitter serotonin (5-hydroxytryptamine; 5-HT) has been implicated in mediating impulsiveness and aggression. To test the hypothesis that 5-HT modulates neuro-cognitive brain activation during inhibitory control, we examined the effect of acute tryptophan depletion (ATD), a dietary challenge, which has been shown to decrease 5-HT synthesis in the brain, on functional brain activation during a go/no-go task.

Methods: Nine healthy, right-handed volunteers performed a rapid, event-related go/no-go task in two functional magnetic resonance imaging (fMRI) scanning sessions, 5 h after either a tryptophan-free or a balanced amino acid drink in a double-blind, sham depletion-controlled, counterbalanced, crossover design.

Neural correlates of the misattribution of self-generated speech.

Auditory hallucinations are thought to arise through the misidentification of self-generated verbal material as alien. The neural mechanisms that normally mediate the differentiation of self-generated from nonself speech are unclear. We investigated this in healthy volunteers using functional MRI.

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.

Neural correlates of syntax production in schizophrenia.

Background: The production of grammatically complex sentences is impaired in schizophrenia. It has been suggested that impaired syntax processing reflects a risk for the disorder.

Aims: To examine the neural correlates of syntax production in people with schizophrenia using functional magnetic resonance imaging (fMRI).

A differential pattern of neural response toward sad versus happy facial expressions in major depressive disorder.

Background: Accurate recognition of facial expressions is crucial for social functioning. In depressed individuals, implicit and explicit attentional biases away from happy and toward sad stimuli have been demonstrated. These may be associated with the negative cognitions in these individuals.

BOLD, sweat and fears: fMRI and skin conductance distinguish facial fear signals.

It is not known how the brain and autonomic systems interact during perception of facial signals of danger. We recorded blood-oxygen-level-dependent (BOLD) activity using fMRI and simultaneous skin conductance measures of autonomic arousal in healthy subjects. Distinct response profiles were elicited for fear (enhanced arousal with amygdala activity), anger (rapid onset, slow recovery arousal responses with anterior cingulate) and disgust (delayed arousal responses with insula and basal ganglia activity).

Cortical effects of quetiapine in first-episode schizophrenia: a preliminary functional magnetic resonance imaging study.

Background: Quetiapine improves both psychotic symptoms and cognitive function in schizophrenia. The neural basis of these actions is poorly understood.

Methods: Three subject groups underwent a single functional magnetic resonance imaging (fMRI) session: drug-naive (n = 7) and quetiapine-treated samples of patients with schizophrenia (n = 8) and a healthy control group (n = 8).

Temporal course of auditory hallucinations.

We used functional magnetic resonance imaging to examine how brain activity associated with auditory verbal hallucinations in schizophrenia changed during hallucinatory events. Activation in the left inferior frontal and right middle temporal gyri was evident 6-9 s before the person signalled the onset of the hallucination, whereas activation in the bilateral temporal gyri and the left insula coincided with the perception of the hallucination. This supports the hypothesis that during hallucinations activation in cortical regions mediating the generation of inner speech may precede the engagement of areas implicated in the perception of auditory verbal material.

A functional MRI study of working memory task in euthymic bipolar disorder: evidence for task-specific dysfunction.

Objectives: Even when euthymic bipolar disorder patients can have persistent deficits in working memory, but the neural basis of this deficit remains unclear. We undertook an functional magnetic resonance imaging investigation of euthymic bipolar disorder patients performing two working memory paradigms; the two-back and Sternberg tasks, selected to examine the central executive and the phonological loop respectively. We hypothesized that neuronal dysfunction would be specific to the network underlying the executive rather than the phonological loop component of working memory.