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Results for “Dorsolateral Prefrontal Cortex”

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PubMed2002

Proton magnetic resonance spectroscopic imaging in pediatric major depression.

BACKGROUND: Neurobiologic abnormalities in dorsolateral prefrontal cortex (DLPFC) are believed to be involved in the pathophysiology of major depressive disorder (MDD). Although MDD commonly emerges during childhood and adolescence, to our knowledge, no prior study has examined the DLPFC in pediatric patients with MDD. METHODS: In this study, choline compounds (Cho), N-acetylaspartate (NAA), and creatine/phosphocreatine (Cr) were measured in left and right DLPFC using a multislice proton magnetic resonance spectroscopic imaging sequence with validated phantom replacement methodology in 11 treatment-naïve MDD patients, 10-16 years of age, and 11 case-matched healthy control subjects. RESULTS: A significant increase in Cho was observed in left but not right DLPFC in MDD patients versus control subjects (32.5% higher). No significant differences in NAA or Cr were observed between case-control pairs. CONCLUSIONS: These results provide new evidence of localized functional neurochemical marker alterations in left DLPFC in pediatric MDD. Our results must be considered preliminary, however, given the small sample size.

Adolescent↗

PubMed2002

Cerebral blood flow during anticipation of public speaking in social phobia: a PET study.

BACKGROUND: The aim was to examine the neural correlates of anxiety elicited by the anticipation of public speaking in individuals with social phobia. Positron emission tomography and (15)O-water was used to measure regional cerebral blood flow in subjects with DSM-IV defined social phobia during anxiety anticipation. Heart rate and subjective anxiety were also recorded. While being scanned, subjects were speaking alone either before or after speaking in public. To evaluate anticipatory anxiety we compared individuals speaking alone before they were speaking in front of an audience with those who did the reverse. RESULTS: Heart rate and subjective anxiety measures confirmed anticipatory anxiety in social phobics who performed their private speech before their public. This was accompanied by enhanced cerebral blood flow in the right dorsolateral prefrontal cortex, left inferior temporal cortex, and in the left amygdaloid-hippocampal region. Brain blood flow was lower in the left temporal pole and bilaterally in the cerebellum in the anticipation group. CONCLUSIONS: Brain regions with altered perfusion presumably reflect changes in neural activity associated with worry about anticipated public performance. We speculate that anticipatory anxiety in social phobics originates in an affect sensitive fear network encompassing the amygdaloid-hippocampal region, prefrontal, and temporal areas.

Adult↗

PubMed2003

A randomized controlled comparison of electroconvulsive therapy and repetitive transcranial magnetic stimulation in severe and resistant nonpsychotic major depression.

BACKGROUND: Studies published over the past few years suggest that transcranial magnetic stimulation (TMS) may have significant antidepressant actions. In a previous report, we compared electroconvulsive therapy (ECT) and repetitive TMS (rTMS) and found ECT to be superior for psychotic major depression (MD); however, ECT and rTMS had similar results in nonpsychotic MD. We now report on a controlled randomized comparison of ECT and rTMS in patients with nonpsychotic MD. METHODS: Forty patients with nonpsychotic MD referred for ECT were included. Electroconvulsive therapy was performed according to established protocols. Repetitive TMS was performed over the left dorsolateral prefrontal cortex at 90% motor threshold. Patients were treated with 20 sessions (five times per week for 4 weeks) of 10-Hz treatments (1200 pulses per treatment-day) at 90% motor threshold. Response to treatment was defined as a decrease of at least 50% in the Hamilton Rating Scale for Depression (HRSD) score, with a final HRSD equal or less than 10 points and a final Global Assessment of Function Scale rating of 60 or more points. RESULTS: The overall response rate was 58% (23 out of 40 patients responded to treatment). In the ECT group, 12 responded and eight did not; in the rTMS group, 11 responded and nine did not (chi2 =.10, ns). Thus, patients responded as well to either ECT or rTMS. CONCLUSIONS: This study adds to the growing literature supporting an antidepressant effect for rTMS. This study is particularly relevant because it suggests that rTMS and ECT reach similar results in nonpsychotic major depressive disorder.

Aged↗

PubMed2003

Cerebral function in posttraumatic stress disorder during verbal working memory updating: a positron emission tomography study.

BACKGROUND: This study examined cerebral function in posttraumatic stress disorder (PTSD) during the updating of working memory to trauma-neutral, verbal information. METHODS: Ten PTSD and matched control subjects completed a visuoverbal target detection task involving continuous updating (Variable target condition) or no updating (Fixed target condition) of target identity, with updating activity estimated by condition comparison. RESULTS: Normal updating activity using this paradigm involved bilateral activation of the dorsolateral prefrontal cortex (DLPFC) and inferior parietal lobe. The PTSD group lacked this activation in the left hemisphere and was significantly different from control subjects in this regard, but showed additional activation in the superior parietal lobe, bilaterally. CONCLUSIONS: The pattern of parietal activation suggests a dependence on visuospatial coding for working memory representation of trauma-neutral, verbal information. Group differences in the relative involvement of the DLPFC indicate less dependence in PTSD on the executive role normally attributed to the left DLPFC for monitoring and manipulation of working memory content in posterior regions of the brain.

Female↗

PubMed2003

Neural circuitry underlying voluntary suppression of sadness.

BACKGROUND: The ability to voluntarily self-regulate negative emotion is essential to a healthy psyche. Indeed, a chronic incapacity to suppress negative emotion might be a key factor in the genesis of depression and anxiety. Regarding the neural underpinnings of emotional self-regulation, a recent functional neuroimaging study carried out by our group has revealed that the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex are involved in voluntary suppression of sexual arousal. As few things are known, still, with respect to the neural substrate underlying volitional self-regulation of basic emotions, here we used functional magnetic resonance imaging to identify the neural circuitry associated with the voluntary suppression of sadness. METHODS: Twenty healthy female subjects were scanned during a Sad condition and a Suppression condition. In the Sad condition, subjects were instructed to react normally to sad film excerpts whereas, in the Suppression condition, they were asked to voluntarily suppress any emotional reaction in response to comparable stimuli. RESULTS: Transient sadness was associated with significant loci of activation in the anterior temporal pole and the midbrain, bilaterally, as well as in the left amygdala, left insula, and right ventrolateral prefrontal cortex (VLPFC) (Brodmann area [BA] 47). Correlational analyses carried out between self-report ratings of sadness and regional blood oxygen level dependent (BOLD) signal changes revealed the existence of positive correlations in the right VLPFC (BA 47), bilaterally, as well as in the left insula and the affective division of the left anterior cingulate gyrus (BA 24/32). In the Suppression condition, significant loci of activation were noted in the right DLPFC (BA 9) and the right orbitofrontal cortex (OFC) (BA 11), and positive correlations were found between the self-report ratings of sadness and BOLD signal changes in the right OFC (BA 11) and right DLPFC (BA 9). CONCLUSIONS: These results confirm the key role played by the DLPFC in emotional self-regulation. They also indicate that the right DLPFC and right OFC are components of a neural circuit implicated in voluntary suppression of sadness.

Adult↗

PubMed1998

A.E. Bennett Research Award. Toward a neurodevelopmental model of of obsessive--compulsive disorder.

BACKGROUND: Neurobiological models for obsessive-compulsive disorder (OCD) have consistently implicated ventral prefrontal cortical and striatal circuits in the pathophysiology of this disorder, but typically have not utilized a developmental framework for conceptualizing the illness. METHODS: We describe an integrated series of neurobiologic studies aimed at testing the hypothesis that neurodevelopmental abnormalities of ventral prefrontal-striatal circuits may be involved in and contribute to the etiology and presentation of the illness. RESULTS: Using studies of oculomotor physiology, we have identified a selective deficit in neurobehavioral response suppression in OCD that may be related to failures in the developmental maturation of frontostriatal circuitry. Magnetic resonance imaging studies showed that treatment-naive pediatric OCD patients had significant volumetric abnormalities in ventral prefrontal cortical and striatal regions but no abnormalities in dorsolateral prefrontal cortex. Severity of OCD symptoms but not illness duration was related to ventral prefrontal cortical and striatal volumes. CONCLUSIONS: Critical neurodevelopmental changes in ventral prefrontal-striatal circuitry may be associated with the initial presentation of OCD, and a developmentally mediated network dysplasia may underlie OCD. Such dysplasia in ventral prefrontal cortical circuits could manifest clinically by disrupting brain functions that mediate ongoing purposive behaviors.

Adolescent↗

PubMed1998

Regionally specific neuronal pathology in untreated patients with schizophrenia: a proton magnetic resonance spectroscopic imaging study.

BACKGROUND: Proton magnetic resonance spectroscopic imaging (1H-MRSI) studies have reported reductions of N-acetyl aspartate (NAA), a marker of neuronal integrity, in the hippocampal region (HIPPO) and dorsolateral prefrontal cortex (DLPFC) of pharmacologically treated patients with schizophrenia. The purpose of the present study was twofold: to exclude drug treatment as a source of the previous findings and to examine NAA relative concentrations in a unique sample of chronically untreated patients. METHODS: We studied 12 medication-free patients, 5 of whom were "drug naive" and symptomatic for a mean of 12 years, and 12 control subjects. Ratios of areas under the metabolite peaks of the proton spectra were determined [i.e., NAA/creatine (CRE), NAA/choline (CHO), CHO/CRE] for multiple cortical and subcortical regions. Hippocampal formation and frontal lobe volumes were also measured to test for correlations with 1H-MRSI data. RESULTS: Significant reductions of NAA/CRE and NAA/CHO were found bilaterally in HIPPO and DLPFC. There were no significant changes in CHO/CRE or in NAA ratios in any other area sampled. No significant correlation was found between metabolite ratios, length of illness, and volumes of the hippocampal region and frontal lobe. Mean ratios and effect sizes were not different in chronically ill but still medication-naive patients in comparison with subacute patients and previously studied chronic patients receiving medications. CONCLUSIONS: Bilateral reductions of NAA ratios in HIPPO and DLPFC are reliable findings. The findings implicate a relatively localized pattern of neurochemical pathology that does not appear to change with prolonged illness whether medicated or unmedicated.

Adult↗

PubMed1998

Depersonalization: neurobiological perspectives.

Depersonalization remains a fascinating and obscure clinical phenomenon. In addition to earlier Jacksonian neurobiological adumbrations, and conventional psychodynamic accounts, views started to be expressed in the 1930s that depersonalization might be a vestigial form of behavior, and since the 1960s that it might be a phenomenon related to the temporal lobe. Recent advances in the neurobiology of the limbic system, and the application of Geschwind's concept of disconnection in the corticolimbic system, have opened the possibility of developing testable models. This paper includes a review of these ideas and of the clinical features of depersonalization, particularly of its emotional changes, suggesting that they are important for the neurobiological understanding of depersonalization. It also draws attention to clinical similarities between the experiential narratives produced by patients suffering from depersonalization and those with corticolimbic disconnections. On the basis of this, a new model is proposed according to which the state of increased alertness observed in depersonalization results from an activation of prefrontal attentional systems (right dorsolateral prefrontal cortex) and reciprocal inhibition of the anterior cingulate, leading to experiences of "mind emptiness" and "indifference to pain" often seen in depersonalization. On the other hand, a left-sided prefrontal mechanism would inhibit the amygdala resulting in dampened autonomic output, hypoemotionality, and lack of emotional coloring that would in turn, be reported as feelings of "unreality or detachment."

Adaptation, Biological↗

PubMed1998

Hippocampal N-acetyl aspartate in unaffected siblings of patients with schizophrenia: a possible intermediate neurobiological phenotype.

BACKGROUND: Shared neurobiological characteristics of patients with schizophrenia and their siblings may represent "intermediate phenotypes" that may more closely reflect the genetic susceptibility underlying this illness. We sought evidence of such phenotypes using magnetic resonance spectroscopy based on previously described regional abnormalities in levels of the neuronal marker N-acetyl-aspartate (NAA) in the hippocampal area and dorsolateral prefrontal cortex of patients with schizophrenia. METHODS: We studied 47 schizophrenics, 60 unaffected siblings, and 66 healthy control subjects with long echo time multislice proton magnetic resonance spectroscopic imaging, primarily measuring NAA, creatine plus phosphocreatine (CRE), and choline-containing compounds. RESULTS: Both patients and their unaffected siblings had significant reductions in hippocampal area NAA/CRE as compared with control subjects. As exploratory analyses, estimates of heritability were performed. Although quantitative correlation of hippocampal NAA between patients and sibs was low (likely reflecting measurement noise), qualitatively defined "low hippocampal NAA/CRE phenotypes" yielded relative risk estimates (lambda s) of between 3.8 and 8.8, suggesting this characteristic is heritable. CONCLUSIONS: Our finding adds to the evidence that hippocampal abnormalities are associated with schizophrenia and may represent a novel biological phenotype for genetic studies of schizophrenia.

Adult↗

PubMed1999

Altered GABA neurotransmission and prefrontal cortical dysfunction in schizophrenia.

Dysfunction of the dorsolateral prefrontal cortex appears to be a central feature of the pathophysiology of schizophrenia, and this dysfunction may be related to alterations in gamma aminobutyric acid (GABA) neurotransmission. Determining the causes and consequences of altered GABA neurotransmission in schizophrenia, and the relationship of these changes to other abnormalities in prefrontal cortical circuitry, requires an understanding of which of the multiple subpopulations of cortical GABA neurons are affected. The chandelier class of GABA neurons, especially those located in the middle layers of the prefrontal cortex (PFC), have been hypothesized to be preferentially involved in schizophrenia because they 1) receive direct synaptic input from dopamine axons, 2) exert powerful inhibitory control over the excitatory output of layer 3 pyramidal neurons, and 3) undergo substantial developmental changes during late adolescence, the typical age of onset of schizophrenia. Consistent with this hypothesis, the axon terminals of chandelier neurons, as revealed by immunoreactivity for the GABA membrane transporter, are reduced substantially in the middle layers of the PFC in schizophrenic subjects. This alteration appears to be selective for the chandelier class of GABA neurons and for the disease process of schizophrenia. These findings provide insight into the pathophysiologic mechanisms underlying prefrontal cortical dysfunction in schizophrenia, and they reveal new targets for therapeutic intervention in this illness.

Adolescent↗

PubMed2000

A randomized clinical trial of repetitive transcranial magnetic stimulation in the treatment of major depression.

BACKGROUND: Multiple groups have reported on the use of repetitive transcranial magnetic stimulation (rTMS) in treatment-resistant major depression. The purpose of this study is to assess the efficacy of rTMS in unmedicated, treatment-resistant patients who meet criteria for major depression. METHODS: Depressed subjects, who had failed to respond to a median of four treatment trials, were assigned in a randomized double-blind manner to receive either active (n = 10; 20 2-sec trains of 20 Hz stimulation with 58-sec intervals; delivered at 80% motor threshold with the figure-of-eight coil positioned over the left dorsolateral prefrontal cortex) or sham (n = 10; similar conditions with the coil elevated and angled 45 degrees tangentially to the scalp) rTMS. These sequences were applied during 10 consecutive weekdays. Continuous electroencephalogram sampling and daily motor threshold determinations were also obtained. RESULTS: The group mean 25-item Hamilton Depression Rating Scale (HDRS) score was 37.2 (+/- 2.0 SEM) points. Adjusted mean decreases in HDRS scores were 14.0 (+/- 3.7) and 0.2 (+/- 4.1) points for the active and control groups, respectively (p <.05). One of 10 subjects receiving active treatment demonstrated a robust response (i.e., HDRS decreased from 47 to 7 points); three other patients demonstrated 40-45% decreases in HDRS scores. No patients receiving sham treatment demonstrated partial or full responses. CONCLUSIONS: A 2-week course of active rTMS resulted in statistically significant but clinically modest reductions of depressive symptoms, as compared to sham rTMS in a population characterized by treatment resistance.

Adolescent↗

PubMed2006

Why is Broca's area involved in syntax?

It is suggested that, rather than Broca's area playing its role in syntactic comprehension because its functions are a specialization those of the dorsolateral prefrontal cortex (DLPFC) or derived from sensori-motor functions of cortex from which it is evolutionarily descended, this region may be involved in this aspect of language because of its intrinsic neural organization.

Biological Evolution↗

PubMedDate not supplied

[Visuospatial context processing in untreated schizophrenic patients and relation to disorganization syndrome].

AIM: Previous studies on schizophrenia have suggested that context-processing disturbances were one of the core cognitive deficits present in schizophrenia. Schizophrenic patients have a failure either of inhibition strategy and maintenance of visuospatial information (25) in condition of contextual interference. In the present study, we explored the performances of untreated schizophrenic patients with 2 tasks exploring detection and long term retention of complex visual features and field dependence-independence tasks were selected. These abilities involve temporary maintenance of visuospatial information and executive functioning of visual working memory system. Several studies have shown that cognitive deficit may depend on schizophrenic symptomatology. However results remain controversial in determining the specific influence of negative and positive symptomatologies as well as clinical disorganization. Our goal was to explore the processing of spatial context and its relation to disorganized syndrome. This study was approved by the local ethic committee. METHODOLOGY: Thirty-six schizophrenic patients were included according to DSM IV criteria (19 neuroleptic naïve, 17 unmedicated patients during more than 3 months). Thirty-six healthy controls were matched to patients for age, gender and level of education. Absence of axis 1 pathology was attested for controls with SCID-NP. Current symptomatology was evaluated by the Positive and Negative Syndrome Scale (PANSS) (14). Clinical disorganisation was evaluated with the disorganisation score established upon a factorial analysis of PANSS by Lepine and Lançon. Items selected to distinguish the disorganised group were abstraction, disorganization, orientation, and attention. PROCEDURE: Two tasks of embedded figures were administered individually to patients and controls. The Faverge task (Research of Figures-RF) (10) evaluates the ability to recognize the target from spatial complex geometrical figures. The Group Embedded Figure Task (GEFT - Oltman) assesses the detection and maintenance of visual target and its recognition within a complex figure. Performance between patients and controls were compared with the Student T test. The comparison of two clinical subgroups of disorganized and low disorganized patients and control group was performed with an ANOVA. Tuckey test was used for pairwise comparisons. RESULTS: We defined two subgroups of patients, disorganized patients (subscore 12, n=17) and low disorganized patients (subscore<12, n=19). Theses 2 subgroups were similar for age and level of education. Concerning the two tasks, there was no significant difference between schizophrenic patients and normal controls. The comparison between subgroups of disorganized and low disorganized patients, for RF task, showed a decrease of correct answers with disorganized patients (p<0.05). For GEFT task, disorganized patients had a decrease of correct answers p<0.01) and more errors (p<0.01) and omissions (p<0.05). The low disorganized patients exhibited for the two tests comparable performance to controls. The disorganized patients had a decrease of right answers (p<0.05) and more errors (p<0.05) than controls for GEFT task and no significant difference for RF. However, with IQ (evaluated with an abstract reasoning test) introduced as covariate, only correct answers for GEFT task remain significant (p<0.05). DISCUSSION: The weak performance of disorganized schizophrenic patients for two tasks RF and GEFT showed that treatment of visuospatial information was impaired in the first perceptive phase of selection and in the organization of information (RF), especially with the maintenance of visual information in memory (GEFT). By contrast, low disorganized patients demonstrated a correct analytic treatment of elementary processing and visuospatial working memory. CONCLUSION: The severity of disorganization influences the visuospatial context processing and visuospatial working memory. These results show the heterogeneity of cognitive functioning regarding to schizophrenic symptomatologies. This difficulty could be related to a problem of central executive functioning in the visuospatial component of working memory, possibly mediated by the dysfunction of dorsolateral prefrontal cortex.

Adult↗

PubMedDate not supplied

Add-on rTMS for treatment of depression: a pilot study using stereotaxic coil-navigation according to PET data.

OBJECTIVE: Repetitive transcranial magnetic stimulation (rTMS) is regarded as a potentially new tool to treat depression. In a double-blind, randomized, sham-controlled pilot study we investigated the efficacy of neuronavigated rTMS, guided according to the prefrontal metabolic state determined by positron emission tomography (PET). METHODS: 25 patients with major depression were included. Prior to rTMS, PET scans were obtained. For the real stimulation condition, the dorsolateral prefrontal cortex (DLPFC) with lower metabolic activity compared to the contralateral hemisphere was selected, if detected by prior PET. Stimulation parameters were 15 Hz, 110% motor threshold (MT), 3000 stimuli/day, for 10 days. A neuronavigational system was used to place the magnetic coil above each individuals' selected cortical region (real condition: DLPFC, sham: midline parieto-occipital, intensity 90% of MT). RTMS was administered add-on to medication. Depression-related symptoms were rated with Beck's, Hamilton's (HAM-D), and Montgomery-Asberg's (MADRS) depression rating scales. RESULTS: Real stimulation improved depression according to HAM-D and MADRS moderately but significantly better compared to sham at the end of the stimulation sessions. In the real condition, four out of 13 patients responded with a mean improvement in HAM-D and/or MADRS of at least 50%, whereas none responded to sham. Antidepressant effects of stimulation of the relatively hypometabolic DLPFC were comparable to stimulation in absence of metabolic differences. CONCLUSIONS: A moderate improvement of depressive symptoms after rTMS was observed. Our preliminary data show that stimulation of prefrontal hypometabolism may not be advantageous to stimulation irrespective of the metabolic state.

Adult↗

PubMed2001

Neural activity associated with episodic memory for emotional context.

To address the question of which brain regions subserve retrieval of emotionally-valenced memories, we used event-related fMRI to index neural activity during the incidental retrieval of emotional and non-emotional contextual information. At study, emotionally neutral words were presented in the context of sentences that were either negatively, neutrally or positively valenced. At test, fMRI data were obtained while participants discriminated between studied and unstudied words. Recognition of words presented in emotionally negative relative to emotionally neutral contexts was associated with enhanced activity in right dorsolateral prefrontal cortex, left amygdala and hippocampus, right lingual gyrus and posterior cingulate cortex. Recognition of words from positive relative to neutral contexts was associated with increased activity in bilateral prefrontal and orbitofrontal cortices, and left anterior temporal lobe. These findings suggest that neural activity mediating episodic retrieval of contextual information and its subsequent processing is modulated by emotion in at least two ways. First, there is enhancement of activity in networks supporting episodic retrieval of neutral information. Second, regions known to be activated when emotional information is encountered in the environment are also active when emotional information is retrieved from memory.

Adolescent↗

PubMed2002

MRI brain scan analyses and neuropsychological profiles of nine patients with persisting unilateral neglect.

Systematic individual neuroanatomical (MRI) and neuropsychological investigations were conducted for nine patients with unilateral neglect persisting at least 3 months after a cerebral vascular accident. The pattern of referrals, together with subsequent investigation, demonstrates that persisting neglect is rare in both right- and left-hemispheric lesioned patients. But while persisting neglect following a left-hemispheric lesion is even rarer than following a right-hemispheric lesion, it does occur. The neuroanatomical results indicate that persisting neglect may be associated with a different pattern of damage from acute neglect. In the nine patients investigated, persisting neglect reflected extensive lesions that involved three or more cortical lobes or subcortical regions. The results support previous findings that parietal lesions are common but not essential for persisting neglect. In the seven of nine neglect patients with parietal lesions, the rostral inferior parietal lobe and the parietal-frontal junction were involved. Of note was the finding that the brain regions most commonly implicated were the basal ganglia and the superior dorsolateral prefrontal cortex (including the frontal eye field). All of the patients with persisting neglect had a range of neuropsychological deficits, including extinction, personal neglect, and anosognosia for one or more aspects of their neglect. Although it was not possible to demonstrate a double dissociation with this pattern of results, the findings indicate that extinction and anosognosia are dissociable into function-specific forms. Most of the neglect patients also had sustained attention deficits, visual memory problems, and visuospatial constructional difficulties.

Adolescent↗

PubMed2002

Deficits in the initiation of eye movements in the absence of a visual target in adolescents with high functioning autism.

BACKGROUND: We used ocular motor paradigms to examine whether or not saccades are impaired in individuals with high functioning autism (HFA). METHODS: We recorded eye movements in patients with HFA (n=11), and in normal adolescents (n=11) on anti-saccade, memory-guided saccade (MGS), predictive saccade and gap/overlap tasks. RESULTS: Compared with the normal subjects, patients with HFA had (1) a significantly higher percentage of directional errors on the anti-saccade task (63.2% versus 26.6%), (2) a significantly higher percentage of response suppression errors on a MGS task (60.3% versus 29.5%) and (3) a significantly lower percentage of predictive eye movements on a predictive saccade task. They also showed longer latencies on a MGS task and for all conditions tested on a gap/null/overlap task (fixation target extinguished before, simultaneously, or after the new peripheral target appeared). When the latencies during the gap condition were subtracted from the latencies in the overlap condition, there was no difference between patients and normals. CONCLUSIONS: Abnormalities in ocular motor function in patients with HFA provide preliminary evidence for involvement of a number of brain regions in HFA including the dorsolateral prefrontal cortex (dlPFC) and the frontal eye fields (FEFs) and possibly the basal ganglia and parietal lobes.

Adolescent↗

PubMed2003

Brain activation patterns during measurement of sub- and supra-second intervals.

The possibility that different neural systems are used to measure temporal durations at the sub-second and several second ranges has been supported by pharmacological manipulation, psychophysics, and neural network modelling. Here, we add to this literature by using fMRI to isolate differences between the brain networks which measure 0.6 and 3s in a temporal discrimination task with visual discrimination for control. We observe activity in bilateral insula and dorsolateral prefrontal cortex, and in right hemispheric pre-supplementary motor area, frontal pole, and inferior parietal cortex during measurement of both intervals, suggesting that these regions constitute a system used in temporal discrimination at both ranges. The frontal operculum, left cerebellar hemisphere and middle and superior temporal gyri, all show significantly greater activity during measurement of the shorter interval, supporting the hypotheses that the motor system is preferentially involved in the measurement of sub-second intervals, and that auditory imagery is preferentially used during measurement of the same. Only a few voxels, falling in the left posterior cingulate and inferior parietal lobe, are more active in the 3s condition. Overall, this study shows that although many brain regions are used for the measurement of both sub- and supra-second temporal durations, there are also differences in activation patterns, suggesting that distinct components are used for the two durations.

Adult↗