Biomedical subjects

Marcello Nardini

Publications and source records attributed to Marcello Nardini.

9 recordsLinked to original sources

PubMed2006

Preferential responses in amygdala and insula during presentation of facial contempt and disgust.

Some authors consider contempt to be a basic emotion while others consider it a variant of disgust. The neural correlates of contempt have not so far been specifically contrasted with disgust. Using functional magnetic resonance imaging (fMRI), we investigated the neural networks involved in the processing of facial contempt and disgust in 24 healthy subjects. Facial recognition of contempt was lower than that of disgust and of neutral faces. The imaging data indicated significant activity in the amygdala and in globus pallidus and putamen during processing of contemptuous faces. Bilateral insula and caudate nuclei and left as well as right inferior frontal gyrus were engaged during processing of disgusted faces. Moreover, direct comparisons of contempt vs. disgust yielded significantly different activations in the amygdala. On the other hand, disgusted faces elicited greater activation than contemptuous faces in the right insula and caudate. Our findings suggest preferential involvement of different neural substrates in the processing of facial emotional expressions of contempt and disgust.

Adult↗

PubMed2006

Prefrontal-hippocampal coupling during memory processing is modulated by COMT val158met genotype.

BACKGROUND: Studies in humans and in animals have demonstrated that a network of brain regions is involved in performance of declarative and recognition memory tasks. This network includes the hippocampal formation (HF) as well as the ventrolateral prefrontal cortex (VLPFC). Studies in animals have suggested that the relationship between these brain regions is strongly modulated by dopamine. METHODS: Using fMRI in healthy humans matched for a series of demographic and genetic variables, we studied the effect of the COMT val158met polymorphism on function of HF and VLPFC as well as on their functional coupling during recognition memory. RESULTS: The COMT Val allele was associated with: relatively poorer performance at retrieval; reduced recruitment of neuronal resources in HF and increased recruitment in VLPFC during both encoding and retrieval; and unfavorable functional coupling between these two regions at retrieval. Moreover, functional coupling during retrieval was predictive of behavioral accuracy. CONCLUSIONS: These results shed new light on individual differences in responsivity and connectivity between HF and VLPFC related to genetic modulation of dopamine, a mechanism accounting at least in part for individual differences in recognition memory performance.

Adult↗

PubMed2006

Additive effects of genetic variation in dopamine regulating genes on working memory cortical activity in human brain.

Functional polymorphisms in the catechol-O-methyltransferase (COMT) and the dopamine transporter (DAT) genes modulate dopamine inactivation, which is crucial for determining neuronal signal-to-noise ratios in prefrontal cortex during working memory. We show that the COMT Met158 allele and the DAT 3' variable number of tandem repeat 10-repeat allele are independently associated in healthy humans with more focused neuronal activity (as measured with blood oxygen level-dependent functional magnetic resonance imaging) in the working memory cortical network, including the prefrontal cortex. Moreover, subjects homozygous for the COMT Met allele and the DAT 10-repeat allele have the most focused response, whereas the COMT Val and the DAT 9-repeat alleles have the least. These results demonstrate additive genetic effects of genes regulating dopamine signaling on specific neuronal networks subserving working memory.

Adult↗

PubMed2005

Variation of human amygdala response during threatening stimuli as a function of 5'HTTLPR genotype and personality style.

BACKGROUND: In the brain, processing of fearful stimuli engages the amygdala, and the variability of its activity is associated with genetic factors as well as with emotional salience. The objective of this study was to explore the relevance of personality style for variability of amygdala response. METHODS: We studied two groups (n=14 in each group) of healthy subjects categorized by contrasting cognitive styles with which they attribute salience to fearful stimuli: so-called phobic prone subjects who exaggerate potential environmental threat versus so-called eating disorders prone subjects who tend to be much less centered around fear. The two groups underwent functional magnetic resonance imaging (fMRI) at 3T during performance of a perceptual task of threatening stimuli and they were also matched for the genotype of the 5' variable number tandem repeat (VNTR) polymorphism in the serotonin transporter. RESULTS: The fMRI results indicated that phobic prone subjects selectively recruit the amygdala to a larger extent than eating disorders prone subjects. Activity in the amygdala was also independently predicted by personality style and genotype of the serotonin transporter. Moreover, brain activity during a working memory task did not differentiate the two groups. CONCLUSIONS: The results of the present study suggest that aspects of personality style are rooted in biological responses of the fear circuitry associated with processing of environmental information.

Adult↗

PubMed2004

Functional lateralization of the sensorimotor cortex in patients with schizophrenia: effects of treatment with olanzapine.

BACKGROUND: Earlier cross-sectional studies with functional magnetic resonance imaging (fMRI) in treated patients with schizophrenia have reported abnormalities of cortical motor processing, including reduced lateralization of primary sensory motor cortex. The objective of the present longitudinal study was to evaluate whether such cortical abnormalities represent state or trait phenomena of the disorder. METHODS: Seventeen acutely ill, previously untreated patients were studied after 4 weeks and after 8 weeks of olanzapine therapy. Seventeen matched healthy subjects served as control subjects. All subjects underwent two fMRI scans 4 weeks apart during a visually paced motor task using a simple periodic block design. Functional magnetic resonance imaging data were analyzed in Statistical Parametric Mapping (SPM99). Region of interest analyses were used to determine a laterality quotient (an index of lateralization) of motor cortical regions. RESULTS: The fMRI data indicated that patients had reduced activation of the primary sensory motor cortex at 4 weeks but not at 8 weeks; however, the laterality quotient in the primary sensory motor cortex was reduced in patients at both time points. CONCLUSIONS: These results suggest that some cortical abnormalities during motor processing represent state phenomena, whereas reduced functional lateralization of the primary sensory motor cortex represents an enduring trait of schizophrenia.

Adolescent↗

PubMed2004

Hippocampal neurochemical pathology in patients at first episode of affective psychosis: a proton magnetic resonance spectroscopic imaging study.

While several studies have suggested a relationship between the hippocampus and psychosis in schizophrenia, fewer studies have specifically investigated the presence of psychosis in mood disorders from a neurobiological perspective. Moreover, a limitation of these earlier studies is that the majority of them were performed in chronic patients. The present proton magnetic resonance spectroscopic imaging (1H-MRSI) study assessed neuronal integrity (as assessed with N-acetylaspartate, NAA) in the hippocampus of patients with a first episode of mood disorders with psychotic symptoms. We studied 17 patients and 17 healthy subjects matched for age and sex. Subjects underwent 1H-MRSI, and measures of NAA, choline-containing compounds (CHO), and creatine+phosphocreatine (CRE) in 11 brain regions were obtained, i.e. hippocampus (HIPPO), dorsolateral prefrontal cortex, superior temporal gyrus, inferior frontal gyrus, occipital cortex, anterior and posterior cingulate, centrum semiovale, prefrontal white matter, thalamus and putamen. NAA/CRE ratios in HIPPO of patients were significantly lower than in controls. Sporadic and non-hypothesis-driven results were found in occipital cortex and prefrontal white matter as a main effect of diagnosis, and in superior temporal gyrus as a hemisphere by diagnosis interaction. These results would not survive a Bonferroni correction for the number of ROIs. No correlations were found with the available demographic and clinical data. Therefore, hippocampal neuronal abnormalities are present at the onset of mood disorders with psychotic symptoms. These data suggest that neuronal abnormalities in HIPPO may be associated with psychosis in mood disorders. Since these data were obtained in patients at first episode, they cannot be explained by chronicity of illness or pharmacological treatment.

Adolescent↗

PubMed2004

Interaction of COMT (Val(108/158)Met) genotype and olanzapine treatment on prefrontal cortical function in patients with schizophrenia.

OBJECTIVE: Deficits in working memory and in prefrontal cortical physiology are important outcome measures in schizophrenia, and both have been associated with dopamine dysregulation and with a functional polymorphism (Val(108/158)Met) in the catechol O-methyltransferase (COMT) gene that affects dopamine inactivation in the prefrontal cortex. The purpose of the present study was to evaluate in patients with schizophrenia the effect of COMT genotype on symptom variation, working memory performance, and prefrontal cortical physiology in response to treatment with an atypical antipsychotic drug. METHOD: Thirty patients with acute untreated schizophrenia were clinically evaluated with the Positive and Negative Syndrome Scale, underwent COMT Val/Met genotyping, and entered an 8-week prospective study of olanzapine treatment. Twenty patients completed two 3-T functional magnetic resonance imaging scans at 4 and 8 weeks during performance of N-back working memory tasks. RESULTS: There was a significant interaction of COMT genotype and the effects of olanzapine on prefrontal cortical function. Met allele load predicted improvement in working memory performance and prefrontal physiology after 8 weeks of treatment. A similar effect was found also for negative symptoms assessed with the Positive and Negative Syndrome Scale. CONCLUSIONS: These results suggest that a genetically determined variation in prefrontal dopamine catabolism impacts the therapeutic profile of olanzapine.

Adult↗

PubMed2003

Gabapentin in antipsychotic-induced tardive dyskinesia: results of 1-year follow-up.

BACKGROUND: In a previous study, improvement of antipsychotic-induced blefarospasm and involuntary oral-mandibulo movements were observed with the use of the anticonvulsant drug gabapentin among affectively ill patients who had been exposed to maintenance neuroleptics. The results reported in the present paper represent the sequel to the previous study. METHODS: The purported efficacy of gabapentin in the treatment of tardive dyskinesia has been assessed in an open design 1-year follow-up study, in which 30 schizoaffective, bipolar I and schizophrenic patients from seven Italian centres were evaluated by means of AIMS. The results showed a statistically significant time-related decrease in AIMS scores. The mean percentage of improvement at AIMS was 47.5+/-18.2%. An improvement of more than 35% after 1 year in 76% of the subjects who completed the trial (n=25) and in 63.3% of the entire sample admitted to the study was revealed. LIMITATION: Open trial. CONCLUSION: The introduction of new antipsychotic drugs has probably already limited the problems related to tardive dyskinesia. However, this type of side-effect is also observed during the course of treatment with atypical neuroleptics albeit with a lesser frequency. The fact that gabapentin treatment may have further improved clinical conditions of patients in whom therapeutic protocols had already been modified, appears to suggest exertion of a possible synergic action by the new neuroleptics on tardive dyskinesia.

Acetates↗

PubMed2003

Working memory deficits and levels of N-acetylaspartate in patients with schizophreniform disorder.

OBJECTIVE: The authors used proton magnetic resonance spectroscopic imaging ((1)H-MRSI) to assess potential reductions of N-acetylaspartate (a marker of neuronal integrity) in the hippocampal area and dorsolateral prefrontal cortex of patients with schizophreniform disorder. In addition, they assessed the relationship between N-acetylaspartate levels and working memory deficits. METHOD: Twenty-four patients with DSM-IV schizophreniform disorder and 24 healthy subjects were studied. Subjects underwent (1)H-MRSI and were given the N-back working memory test. RESULTS: The schizophreniform disorder patients had selective reductions of N-acetylaspartate ratios in the hippocampal area and the dorsolateral prefrontal cortex, and a positive correlation was seen between N-acetylaspartate ratios in the dorsolateral prefrontal cortex and performance during the 2-back working memory condition. CONCLUSIONS: Similar to findings reported in schizophrenia studies, N-acetylaspartate reductions in the hippocampal area and the dorsolateral prefrontal cortex were seen in patients with schizophreniform disorder. Moreover, the results support other evidence that neuronal pathology in the dorsolateral prefrontal cortex accounts for a proportion of working memory deficits already present at illness outset.

Adult↗