Biomedical subjects

Vincent Giampietro

Publications and source records attributed to Vincent Giampietro.

13 recordsLinked to original sources

PubMed2006

Probing the working memory system in chronic fatigue syndrome: a functional magnetic resonance imaging study using the n-back task.

OBJECTIVE: Up to 90% of patients with chronic fatigue syndrome (CFS) report substantial cognitive difficulties. However, objective evidence supporting these claims is inconsistent. The present functional magnetic resonance imaging study examined the neural correlates of working memory in patients with CFS compared with controls. METHODS: Seventeen patients with CFS and 12 healthy control subjects were scanned while performing a parametric version of the n-back task (0-, 1-, 2-, and 3-back). RESULTS: Both groups performed comparably well and activated the verbal working memory network during all task levels. However, during the 1-back condition, patients with CFS showed greater activation than control subjects in medial prefrontal regions, including the anterior cingulate gyrus. Conversely, on the more challenging conditions, patients with CFS demonstrated reduced activation in dorsolateral prefrontal and parietal cortices. Furthermore, on the 2- and 3-back conditions, patients but not control subjects significantly activated a large cluster in the right inferior/medial temporal cortex. Trend analyses of task load demonstrated statistically significant differences in brain activation between the two groups as the demands of the task increased. CONCLUSIONS: These results suggest that patients with CFS show both quantitative and qualitative differences in activation of the working memory network compared with healthy control subjects. It remains to be determined whether these findings stay stable after successful treatment.

Adult↗

PubMed2006

A reversal of the normal pattern of parahippocampal response to neutral and fearful faces is associated with reality distortion in schizophrenia.

BACKGROUND: Individuals with schizophrenia demonstrate impaired recognition of facial expressions and may misattribute emotional salience to otherwise nonsalient stimuli. The neural mechanisms underlying this deficit and the relationship with different symptoms remain poorly understood. METHODS: We used event-related functional magnetic resonance imaging to measure neural responses to neutral, mildly fearful, and prototypically fearful facial expressions. The sample included 15 medicated individuals with chronic schizophrenia (SZ) and 11 healthy control individuals (CON), matched for gender (all male), age, and years of education. RESULTS: A repeated measures 3 x 2 analysis of variance (ANOVA) revealed a significant interaction between expression intensity and group in right parahippocampal gyrus (p < .01). Individuals with chronic schizophrenia demonstrated a decrease, whereas CON showed an increase, in right parahippocampal gyrus response to increasingly fearful expressions. Between-group comparison revealed greater activation in SZ than CON in right parahippocampal gyrus to neutral faces. The reality distortion dimension, but not neuroleptic medication dose, was positively associated with the right parahippocampal gyral and right amygdalar response to neutral faces in SZ. CONCLUSIONS: An abnormally increased parahippocampal response to neutral faces was positively associated with reality distortion in SZ. This may underlie the previously reported finding of a misattribution of emotional salience to nonsalient social stimuli in schizophrenia.

Adult↗

PubMed2006

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. Processing BSL sentences, when contrasted with signed lists, was reliably associated with greater activation in the posterior portions of the left middle and superior temporal gyri and in the left inferior frontal cortex, but not in the anterior temporal cortex, which was activated to a similar extent whether lists or sentences were processed. Further support for the specificity of these areas for processing the linguistic-rather than visuospatial-features of signed sentences came from a contrast of hearing native signers and hearing sign-naïve participants. Hearing signers recruited the left posterior temporal and inferior frontal regions during BSL sentence processing to a greater extent than hearing non-signers. These data suggest that these left perisylvian regions are differentially associated with sentence processing, whatever the modality of the linguistic input.

Adolescent↗

PubMed2006

Facial emotion processing in criminal psychopathy. Preliminary functional magnetic resonance imaging study.

BACKGROUND: It has been suggested that people with psychopathic disorders lack empathy because they have deficits in processing distress cues (e.g. fearful facial expressions). AIMS: To investigate brain function when individuals with psychopathy and a control group process facial emotion. METHOD: Using event-related functional magnetic resonance imaging we compared six people scoring > or =25 on the Hare Psychopathy Checklist-Revised and nine non-psychopathic healthy volunteers during an implicit emotion processing task using fearful, happy and neutral faces. RESULTS: The psychopathy group showed significantly less activation than the control group in fusiform and extrastriate cortices when processing both facial emotions. However, emotion type affected response pattern. Both groups increased fusiform and extrastriate cortex activation when processing happy faces compared with neutral faces, but this increase was significantly smaller in the psychopathy group. In contrast, when processing fearful faces compared with neutral faces, the control group showed increased activation but the psychopathy group decreased activation in the fusiform gyrus. CONCLUSIONS: People with psychopathy have biological differences from controls when processing facial emotion, and the pattern of response differs according to emotion type.

Antisocial Personality Disorder↗

PubMed2005

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. Activation of the left inferior frontal gyrus (LIFG), BA 47, was shared by both non-meaningful and metaphoric sentences but not by literal sentences. Furthermore, activation of the left thalamus appeared to be specifically involved in deriving meaning from metaphoric sentences despite lack of reaction times differences between literals and metaphors. We assign this to the ad hoc concept construction and open-endedness of metaphoric interpretation. In contrast to previous studies, our results do not support the view the right hemispheric is specifically involved in metaphor comprehension.

Adult↗

PubMed2005

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. RESULTS: In the three groups, the lateral fusiform gyrus, inferior parietal cortex, and lateral prefrontal cortex were activated in response to body shapes compared with the control condition (drawings of houses). The responses in the lateral fusiform gyrus and in the parietal cortex were less strong in patients with eating disorders compared with healthy control subjects. Patients with eating disorders rated the body shapes in all weight categories as more aversive than did healthy women. In the group with eating disorders, the aversion ratings correlated positively with activity in the right medial apical prefrontal cortex. CONCLUSIONS: Processing of female body shapes engages a distributed neural network, parts of which are underactive in women with eating disorders. The considerable variability in subjective emotional reaction to body shapes in patients with eating disorders is associated with differential activity in the prefrontal cortex.

Adult↗

PubMed2005

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. METHODS: Using event-related functional magnetic resonance imaging (fMRI), neural responses to happy and sad facial expressions were measured in 14 healthy individuals and 16 individuals with major depressive disorder. RESULTS: Healthy but not depressed individuals demonstrated linear increases in response in bilateral fusiform gyri and right putamen to expressions of increasing happiness, while depressed individuals demonstrated linear increases in response in left putamen, left parahippocampal gyrus/amygdala, and right fusiform gyrus to expressions of increasing sadness. There was a negative correlation in depressed individuals between depression severity and magnitude of neural response within right fusiform gyrus to happy expressions. CONCLUSIONS: Our findings indicate preferential increases in neural response to sad but not happy facial expressions in neural regions involved in the processing of emotional stimuli in depressed individuals. These findings may be associated with the above pattern of implicit and explicit attentional biases in these individuals and suggest a potential neural basis for the negative cognitions and social dysfunction in major depression.

Adult↗

PubMed2004

Subcortical and ventral prefrontal cortical neural responses to facial expressions distinguish patients with bipolar disorder and major depression.

BACKGROUND: Bipolar disorder (BD) is characterised by abnormalities in mood and emotional processing, but the neural correlates of these, their relationship to depressive symptoms, and the similarities with deficits in major depressive disorder (MDD) remain unclear. We compared responses within subcortical and prefrontal cortical regions to emotionally salient material in patients with BP and MDD using functional magnetic resonance imaging. METHODS: We measured neural responses to mild and intense expressions of fear, happiness, and sadness in euthymic and depressed BD patients, healthy control subjects, and depressed MDD patients. RESULTS: Bipolar disorder patients demonstrated increased subcortical (ventral striatal, thalamic, hippocampal) and ventral prefrontal cortical responses particularly to mild and intense fear, mild happy, and mild sad expressions. Healthy control subjects demonstrated increased subcortical responses to intense happy and mild fear, and increased dorsal prefrontal cortical responses to intense sad expressions. Overall, MDD patients showed diminished neural responses to all emotional expressions except mild sadness. Depression severity correlated positively with hippocampal response to mild sadness in both patient groups. CONCLUSIONS: Compared with healthy controls and MDD patients, BD patients demonstrated increased subcortical and ventral prefrontal cortical responses to both positive and negative emotional expressions.

Adult↗

PubMed2004

Dissociating linguistic and nonlinguistic gestural communication in the brain.

Gestures of the face, arms, and hands are components of signed languages used by Deaf people. Signaling codes, such as the racecourse betting code known as Tic Tac, are also made up of such gestures. Tic Tac lacks the phonological structure of British Sign Language (BSL) but is similar in terms of its visual and articulatory components. Using fMRI, we compared the neural correlates of viewing a gestural language (BSL) and a manual-brachial code (Tic Tac) relative to a low-level baseline task. We compared three groups: Deaf native signers, hearing native signers, and hearing nonsigners. None of the participants had any knowledge of Tic Tac. All three groups activated an extensive frontal-posterior network in response to both types of stimuli. Superior temporal cortex, including the planum temporale, was activated bilaterally in response to both types of gesture in all groups, irrespective of hearing status. The engagement of these traditionally auditory processing regions was greater in Deaf than hearing participants. These data suggest that the planum temporale may be responsive to visual movement in both deaf and hearing people, yet when hearing is absent early in development, the visual processing role of this region is enhanced. Greater activation for BSL than Tic Tac was observed in signers, but not in nonsigners, in the left posterior superior temporal sulcus and gyrus, extending into the supramarginal gyrus. This suggests that the left posterior perisylvian cortex is of fundamental importance to language processing, regardless of the modality in which it is conveyed.

Adolescent↗

PubMed2004

Allocentric spatial memory activation of the hippocampal formation measured with fMRI.

Hippocampal activation was investigated, comparing allocentric and egocentric spatial memory. Healthy participants were immersed in a virtual reality circular arena, with pattern-rendered walls. In a viewpoint-independent task, they moved toward a pole, which was then removed. They were relocated to another position and had to move to the prior location of the pole. For viewpoint-dependent memory, the participants were not moved to a new starting point, but the patterns were rotated to prevent them from indicating the final position. Hippocampal and parahippocampal activation were found in the viewpoint-independent memory encoding phase. Viewpoint-dependent memory did not result in such activation. These results suggest differential activation of the hippocampal formation during allocentric encoding, in partial support of the spatial mapping hypothesis as applied to humans.

Adult↗

PubMed2003

Neural abnormalities during cognitive generation of affect in treatment-resistant depression.

BACKGROUND: Dysfunctions in brain regions known to be involved in affect and mood states are thought to be implicated in depression and may have a role in determining the type and symptoms of this illness. METHODS: Functional magnetic resonance imaging was used to elucidate neural correlates of cognitive generation of affect, using a previously published paradigm of evoking affect with picture-caption pairs, in patients with unipolar, treatment-resistant depression. RESULTS: Compared with control participants, patients showed relatively decreased response in the anterior cingulate (rostral; right) with both negative and positive picture-caption pairs and in the medial frontal gyrus and hippocampus (all left) with positive picture-caption pairs. They demonstrated increased response in the inferior (right) and middle temporal gyri (left) with negative picture-caption pairs, and in the parahippocampal gyrus (right), inferior frontal gyrus (left), subgenual cingulate (right), striatum (right), and brain stem (left) with positive picture-caption pairs. CONCLUSIONS: Reduced medial/middle prefrontal and hippocampal activity may account for positive affect disturbances and temporal lobe hyperactivity for negative affect disturbances in treatment-resistant depression. The results also corroborate previous observations from resting positron emission tomography studies and further elucidate the association between hypoactive rostral cingulate and nonresponsiveness to treatment in depression.

Adult↗

PubMed2003

The effect of negative emotional context on neural and behavioural responses to oesophageal stimulation.

Sensory experience is influenced by emotional context. Although perception of emotion and unpleasant visceral sensation are associated with activation within the insula and dorsal and ventral anterior cingulate gyri (ACG), regions important for attention to and perception of sensory and emotional information, the neural mechanisms underlying the effect of emotional context upon visceral sensation remain unexplored. Using functional MRI, we examined neural responses to phasic, non-painful oesophageal sensation (OS) in eight healthy subjects (seven male; age range 27-36 years) either during neutral or negative emotional contexts produced, respectively, by presentation of neutral or fearful facial expressions. Activation within right insular and bilateral dorsal ACG was significantly greater (P < 0.01) during OS with fearful than with neutral faces. In a second experiment, we measured anxiety, discomfort and neural responses in eight healthy male subjects (age range 22-41 years) to phasic, non-painful OS during presentation of faces depicting either low, moderate or high intensities of fear. Significantly greater (P < 0.01) discomfort, anxiety and activation predominantly within the left dorsal ACG and bilateral anterior insulae occurred with high-intensity compared with low-intensity expressions. Clusters of voxels were also detected in this region, which exhibited a positive correlation between subjective behaviour and blood oxygenation level-dependent effect (P < 0.05). We report the first evidence for a modulation of neural responses, and perceived discomfort during, non-painful visceral stimulation by the intensity of the negative emotional context in which the stimulation occurs, and suggest a mechanism for the effect of negative context on symptoms in functional pain disorders.

Adult↗

PubMed1998

Storage of verbal associations is sufficient to activate the left medial temporal lobe.

Neuroimaging studies have shown that memory encoding activates the medial temporal lobe (MTL). Many believe that these activations are related to novelty but it remains unproven which is critical - novelty detection or the rich associative encoding it triggers. We examined MTL activation during verbal associative encoding using functional magnetic resonance imaging. First, associative encoding activated left posterior MTL more than single word encoding even though novelty detection was matched, indicating not only that associative encoding activates the MTL particularly strongly, but also that activation does not require novelty detection. Moreover, it remains to be convincingly shown that novelty detection alone does produce such activation. Second, repetitive associative encoding produced less MTL activation than initial associative encoding, indicating that priming of associative information reduces MTL activation. Third, re-encoding familiar associations in a well-established way had a minimal effect on both memory and MTL activation, indicating that MTL activation reflects storage of associations, not merely their initial representation.

Journal Article↗