Search results for "Lateral prefrontal cortex"
showing 10 items of 66 documents
Neural correlates of working memory dysfunction in first-episode schizophrenia patients: an fMRI multi-center study.
2005
Working memory dysfunction is a prominent impairment in patients with schizophrenia. Our aim was to determine cerebral dysfunctions by means of functional magnetic resonance imaging (fMRI) in a large sample of first-episode schizophrenia patients during a working memory task. 75 first-episode schizophrenia patients and 81 control subjects, recruited within a multi-center study, performed 2- and 0-back tasks while brain activation was measured with fMRI. In order to guarantee comparability between data quality from different scanners, we developed and adopted a standardized, fully automated quality assurance of scanner hard- and software as well as a measure for in vivo data quality. After t…
Neural Architecture of Selective Stopping Strategies: Distinct Brain Activity Patterns Are Associated with Attentional Capture But Not with Outright …
2017
In stimulus-selective stop-signal tasks, the salient stop signal needs attentional processing before genuine response inhibition is completed. Differential prefrontal involvement in attentional capture and response inhibition has been linked to the right inferior frontal junction (IFJ) and ventrolateral prefrontal cortex (VLPFC), respectively. Recently, it has been suggested that stimulus-selective stopping may be accomplished by the following different strategies: individuals may selectively inhibit their response only upon detecting a stop signal (independent discriminate then stop strategy) or unselectively whenever detecting a stop or attentional capture signal (stop then discriminate s…
Altered effective connectivity during working memory performance in schizophrenia: a study with fMRI and structural equation modeling
2003
The present study aimed to explore altered effective connectivity in schizophrenic patients while performing a 2-back working memory task. Twelve right-handed, schizophrenic patients treated with typical or atypical antipsychotics and 6 healthy control subjects were studied with fMRI while performing a "2-back" working memory task. Effective connectivity within a cortical-subcortical-cerebellar network for mnemonic information processing was assessed and compared between both groups. The path model included cortico-cortical connections comprising the parietal association cortex, ventrolateral prefrontal cortex (VLPFC), and the dorsolateral prefrontal cortex (DLPFC) as well as a cortico-cere…
COMT genotype predicts BOLD signal and noise characteristics in prefrontal circuits.
2006
Abstract Objective: Prefrontal dopamine (DA) is catabolized by the COMT (catechol- O -methyltransferase) enzyme. Literature suggests that the Val/Met single nucleotide polymorphism (SNP) in the COMT gene predicts executive cognition in humans with Val carriers showing poorer performance due to less available synaptic DA. Recent fMRI studies are thought to agree with these studies having demonstrated prefrontal hyperactivation during n -back and attention-requiring tasks. This was interpreted as “less efficient” processing due to impaired signal-to-noise ratio (SNR) of neuronal activity. However, electrophysiological studies of neuronal SNR in primates and humans imply that prefrontal cortex…
Anodal transcranial direct current stimulation of the right dorsolateral prefrontal cortex enhances memory-guided responses in a visuospatial working…
2014
Several studies have shown that transcranial direct current stimulation (tDCS) is able to enhance performances on verbal and visual working memory (WM) tasks. Available evidence points to the right dorsolateral prefrontal cortex (DLPFC) as a critical area in visual WM, but to date direct comparisons of the effects obtained by stimulating the left versus the right DLPFC in the same subject are lacking. Our aim was to determine whether tDCS over the right DLPFC can differently affect performance as compared with left DLPFC stimulation. Ten healthy subjects performed a memory-guided visuospatial task in three conditions: baseline, during anodal stimulation applied over the right and during ano…
Parieto-frontal interactions in visual-object and visual-spatial working memory: Evidence from transcranial magnetic stimulation
2001
This study aimed to investigate whether transcranial magnetic stimulation (TMS) can induce selective working memory (WM) deficits of visual-object versus visual-spatial information in normal humans. Thirty-five healthy subjects performed two computerized visual n-back tasks, in which they were required to memorize spatial locations or abstract patterns. In a first series of experiments, unilateral or bilateral TMS was delivered on posterior parietal and middle temporal regions of both hemispheres after various delays during the WM task. Bilateral temporal TMS increased reaction times (RTs) in the visual-object, whereas bilateral parietal TMS selectively increased RTs in the visual-spatial W…
Opposite effects of suicidality and lithium on gray matter volumes in bipolar depression
2011
Background: Mood disorders are associated with the highest increase of attempted and completed suicide. Suicidality in major depressive disorder and in schizophrenia has been associated with reduced gray matter volumes in orbitofrontal cortex. Lithium reduces the suicide risk of patients with bipolar disorder (BD) to the same levels of the general population, and can increase GM volumes. We studied the effect of a positive history of attempted suicide and ongoing lithium treatment on regional GM volumes of patients affected by bipolar depression. Methods: With a correlational design, we studied 57 currently depressed inpatients with bipolar disorder: 19 with and 38 without a positive histor…
Repetitive TMS over the left dorsolateral prefrontal cortex modulates the error positivity: An ERP study
2019
Abstract Error processing is a critical step towards an efficient adaptation of our behavior to achieve a goal. Little research has been devoted to investigate the contribution of the dorsolateral prefrontal cortex (DLPFC) in supporting error processing. In this study, the causal relationship of the DLPFC in error commission was examined by means of a repetitive transcranial magnetic stimulation protocol (rTMS). Specifically, the effects of an inhibitory protocol were assessed by examining the electroencephalographic signal recorded during the execution of a Go/No-Go task. To this aim, a group of 15 healthy young participants performed a three-session study. At each session, either the righ…
Interest of targeting either cortical area Brodmann 9 or 46 in rTMS treatment for depression: a preliminary randomized study.
2013
Abstract Objective To assess the interest of specifically targeting Brodmann Areas (BA) 9 or 46 for rTMS treatment of depression. Methods Patients with Treatment-Resistant Depression were randomly assigned to two treatment groups to receive either rTMS on BA 9 or on BA 46. Each patient underwent 10 sessions of 1Hz-rTMS for 2weeks. The Hamilton and Montgomery–Asberg Depression Rating Scales (HDRS, MADRS) were used under blind conditions to assess the therapeutic response (50% improvement). A Wilcoxon signed-rank test was used to compare the depression rating scales scores obtained before and after the 10 rTMS sessions for each of the two groups. The therapeutic results in the two groups were…
Modulating memory performance in healthy subjects with Trancranial Direct Current Stimulation over the right dorsolateral prefrontal cortex
2015
Objective: The role of the Dorsolateral Prefrontal Cortex (DLPFC) in recognition memory has been well documented in lesion, neuroimaging and repetitive Transcranial Magnetic Stimulation (rTMS) studies. The aim of the present study was to investigate the effects of transcranial Direct Current Stimulation (tDCS) over the left and the right DLPFC during the delay interval of a non-verbal recognition memory task. Method: 36 right-handed young healthy subjects participated in the study. The experimental task was an Italian version of Recognition Memory Test for unknown faces. Study included two experiments: in a first experiment, each subject underwent one session of sham tDCS and one session of…