Search results for "prefrontal cortex."
showing 10 items of 320 documents
Lateralized effects of self-induced sadness and happiness on corticospinal excitability.
1997
We studied the changes in excitability of the corticospinal projection evoked by self-induced sad and happy thoughts. Corticospinal excitability was probed using focal, single-pulse transcranial magnetic stimulation (TMS) applied to the optimal scalp position for evoking motor potentials in the contralateral first dorsal interosseus muscle. Fourteen right-handed subjects were studied while counting mentally, thinking sad thoughts, or thinking happy thoughts. In each of these three conditions TMS was applied in each subject randomly, 20 times to the right and 20 times to the left hemisphere. Sad thoughts resulted in a significant facilitation of the motor potentials evoked by left-hemispheri…
Recognition memory and prefrontal cortex: Dissociating recollection and familiarity processes using rTMS
2008
Recognition memory can be supported by both the assessment of the familiarity of an item and by the recollection of the context in which an item was encountered. The neural substrates of these memory processes are controversial. To address these issues we applied repetitive transcranial magnetic stimulation (rTMS) over the right and left dorsolateral prefrontal cortex (DLPFC) of healthy subjects performing a remember/know task. rTMS disrupted familiarity judgments when applied before encoding of stimuli over both right and left DLPFC. rTMS disrupted recollection when applied before encoding of stimuli over the right DLPFC. These findings suggest that the DLPFC plays a critical role in recog…
High frequency repetitive transcranial magnetic stimulation (rTMS) reduces EEG-hypofrontality in patients with schizophrenia.
2015
The reduced metabolic activity in the prefrontal brain lobes, so-called hypofrontality, is associated with increased electrophysiological delta-band activity. Schizophrenia inpatients (N=35) received sham-controlled 10Hz rTMS over the left dorsolateral prefrontal cortex in a randomised design. After treatment, the resting electroencephalography revealed a significant decrease in the delta-band activity, which originated in the right prefrontal cortex and correlated with improvements in facial affect recognition.
Excitability regulation in the dorsomedial prefrontal cortex during sustained instructed fear responses: a TMS-EEG study
2018
AbstractThreat detection is essential for protecting individuals from adverse situations, in which a network of amygdala, limbic regions and dorsomedial prefrontal cortex (dmPFC) regions are involved in fear processing. Excitability regulation in the dmPFC might be crucial for fear processing, while abnormal patterns could lead to mental illness. Notwithstanding, non-invasive paradigms to measure excitability regulation during fear processing in humans are missing. To address this challenge we adapted an approach for excitability characterization, combining electroencephalography (EEG) and transcranial magnetic stimulation (TMS) over the dmPFC during an instructed fear paradigm, to dynamica…
Keeping memory clear and stable--the contribution of human basal ganglia and prefrontal cortex to working memory.
2010
Successful remembering involves both hindering irrelevant information from entering working memory (WM) and actively maintaining relevant information online. Using a voxelwise lesion-behavior brain mapping approach in stroke patients, we observed that lesions of the left basal ganglia render WM susceptible to irrelevant information. Lesions of the right prefrontal cortex on the other hand make it difficult to keep more than a few items in WM. These findings support basal ganglia-prefrontal cortex models of WM whereby the basal ganglia play a gatekeeper role and allow only relevant information to enter prefrontal cortex where this information then is actively maintained in WM.
Neural correlates of antinociception in borderline personality disorder.
2006
Context A characteristic feature of borderline personality disorder (BPD) is self-injurious behavior in conjunction with stress-induced reduction of pain perception. Reduced pain sensitivity has been experimentally confirmed in patients with BPD, but the neural correlates of antinociceptive mechanisms in BPD are unknown. We predicted that heat stimuli in patients with BPD would activate brain areas concerned with cognitive and emotional evaluation of pain. Objective To assess the psychophysical properties and neural correlates of altered pain processing in patients with BPD. Design Case-control study. Setting A university hospital. Participants Twelve women with BPD and self-injurious behav…
Neurobiological signature of intimacy in anorexia nervosa
2019
Background Intimacy and psychosexual development represent core problems of anorexia nervosa (AN). Experiential and neurobiological evidence however is scarce. Material and methods Thirty-one female AN patients were compared with 35 non-patients (NP) and 22 recovered participants (REC) by using functional magnetic resonance imaging. Participants viewed pictures of couples in intimate relationships and control stimuli. Results AN patients experienced intimate stimuli with lower valence and dominance. AN showed decreased activation of parietal cortices. NP decreased the prefrontal cortex response, which AN patients did not. REC participants did not differ from NP on a behavioural level, thoug…
Alterations in the expression of PSA-NCAM and synaptic proteins in the dorsolateral prefrontal cortex of psychiatric disorder patients.
2012
Alterations in the structure and physiology of the prefrontal cortex (PFC) have been found in different psychiatric disorders and some of them involve inhibitory networks, especially in schizophrenia and major depression. Changes in the structure of these networks may be mediated by the polysialylated neural cell adhesion molecule (PSA-NCAM), a molecule related to neuronal structural plasticity, expressed in the PFC exclusively by interneurons. Different studies have found that PSA-NCAM expression in the hippocampus and the amygdala is altered in schizophrenia, major depression and animal models of these disorders, in parallel to changes in the expression of molecules related to inhibitory …
Semaphorin and plexin gene expression is altered in the prefrontal cortex of schizophrenia patients with and without auditory hallucinations
2015
Auditory hallucinations (AH) are clinical hallmarks of schizophrenia, however little is known about molecular genetics of these symptoms. In this study, gene expression profiling of postmortem brain samples from prefrontal cortex of schizophrenic patients without AH (SNA), patients with AH (SA) and control subjects were compared. Genome-wide expression analysis was conducted using samples of three individuals of each group and the Affymetrix GeneChip Human-Gene 1.0 ST-Array. This analysis identified the Axon Guidance pathway as one of the most differentially expressed network among SNA, SA and CNT. To confirm the transcriptome results, mRNA level quantification of seventeen genes involved i…
Attention to pain is processed at multiple cortical sites in man.
2004
Painful cutaneous laser stimuli evoked potentials (LEPs) were recorded over the primary somatosensory (SI), parasylvian, and medial frontal (MF) cortex areas in a patient with subdural electrode grids located over these areas for surgical treatment of epilepsy. The amplitudes of the negative (N2*) and positive (P2**) LEP peaks over SI, parasylvian, and MF cortex were enhanced by attention to (counting stimuli), in comparison with distraction from the stimulus (reading for comprehension). Late positive deflections following the P2** peak (late potential—LP) were recorded over MF and from the lateral premotor regions during attention but not during distraction. These findings suggest that att…