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Elevation of cell adhesion molecule immunoreactivity in the anterior cingulate cortex in bipolar disorder.

BACKGROUND: Neuroimaging reports of increases in signal hyperintensities in white and deep gray matter and other work indicate that there might be an inflammatory response in affective disorders. METHODS: The microvascular immunoreactivity of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 was measured with image analysis in postmortem tissue from the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC) from 15 unipolar and 15 bipolar subjects and compared with each other and with 15 subjects with schizophrenia and 15 control subjects. RESULTS: Intercellular adhesion molecule-1 immunoreactivity in gray and white matter of the ACC in bipolar subjects was increased compared with control subjects (gray: p =.001; white: p <.001) and schizophrenic subjects (gray: p =.016; white: p =.025) and modestly increased in white matter compared with unipolar subjects (p =.049). No such differences were found in the DLPFC. CONCLUSIONS: These findings are consistent with the presence of an inflammatory response in the ACC in bipolar disorder.

Adult↗

Functional lesions and human action monitoring: combining repetitive transcranial magnetic stimulation and event-related brain potentials.

OBJECTIVE: Electrophysiological recordings of the error-related negativity (ERN) and functional imaging data point to an involvement of medial frontal cortex (including the anterior cingulate cortex, ACC) and dorsolateral prefrontal cortex (DLPFC) in the detection and correction of performance errors. Here, we studied this network by applying trains of rapid transcranial magnetic stimulation (rTMS) prior to the recording of the ERN. METHODS: Low-frequency (0.9 Hz) rTMS was applied to medial frontal or lateral frontal regions (different sessions) for 60 s immediately before each 3 min ERN recording in 11 healthy young subjects. The ERN was obtained by multichannel recordings in a typical Eriksen flanker task with instructions calling for immediate error correction in case a performance error was detected by the subject. Event-related potentials were quantified and statistically evaluated using standard methodology. RESULTS: Compared to a no-stimulation control condition, medial frontal stimulation led to a small but reliable decrease in the number of corrected errors as well as to an attenuation of the ERN and an increase of the subsequent error-positivity (Pe). No effect on these components was seen after lateral frontal stimulation. No reliable effects on the lateralized readiness potential were observed. CONCLUSIONS: Functional lesions by rTMS appear to interfere with the functions of the medial frontal cortex in error detection and correction.

Adult↗

A parietal-frontal network studied by somatosensory oddball MEG responses, and its cross-modal consistency.

Previous studies using functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs) of the brain have found that a distributed parietal-frontal neuronal network is activated in normals during both auditory and visual oddball tasks. The common cortical regions in this network are inferior parietal lobule (IPL)/supramarginal gyrus (SMG), anterior cingulate cortex (ACC), and dorsolateral prefrontal cortex (DLPFC). It is not clear whether the same network is activated by oddball tasks during somatosensory stimulation. The present study addressed this question by testing healthy adults as they performed a novel median-nerve oddball paradigm while undergoing magnetoencephalography (MEG). An automated multiple dipole analysis technique, the Multi-Start Spatio-Temporal (MSST) algorithm, localized multiple neuronal generators, and identified their time-courses. IPL/SMG, ACC, and DLPFC were reliably localized in the MEG median-nerve oddball responses, with IPL/SMG activation significantly preceding ACC and DLPFC activation. Thus, the same parietal-frontal neuronal network that shows activation during auditory and visual oddball tests is activated in a median-nerve oddball paradigm. Regions uniquely related to somatosensory oddball responses (e.g., primary and secondary somatosensory, dorsal premotor, primary motor, and supplementary motor areas) were also localized. Since the parietal-frontal network supports attentional allocation during performance of the task, this study may provide a novel method, as well as normative baseline data, for examining attention-related deficits in the somatosensory system of patients with neurological or psychiatric disorders.

Adult↗

Functional neuroanatomy of aversion and its anticipation.

The capacity to anticipate aversive circumstances is central not only to successful adaptation but also to understanding the abnormalities that contribute to excessive worry and anxiety disorders. Forecasting and reacting to aversive events mobilize a host of affective and cognitive capacities and corresponding brain processes. Rapid event-related functional magnetic resonance imaging (fMRI) in 21 healthy volunteers assessed the overlap and divergence in the neural instantiation of anticipating and being exposed to aversive pictures. Brain areas jointly activated by the anticipation of and exposure to aversive pictures included the dorsal amygdala, anterior insula, dorsal anterior cingulate cortex (ACC), right dorsolateral prefrontal cortex (DLPFC), and right posterior orbitofrontal cortex (OFC). Anticipatory processes were uniquely associated with activations in rostral ACC, a more superior sector of the right DLPFC, and more medial sectors of the bilateral OFC. Activation of the right DLPFC in anticipation of aversion was associated with self-reports of increased negative affect, whereas OFC activation was associated with increases in both positive and negative affect. These results show that anticipation of aversion recruits key brain regions that respond to aversion, thereby potentially enhancing adaptive responses to aversive events.

Adult↗

Neural correlates of developmental differences in risk estimation and feedback processing.

The primary aim of this study was to compare the neural substrates of decision-making in middle-aged children and adults. To this end, we collected fMRI data while 9-12-year-olds and 18-26-year-olds performed a simple gambling task. The task was designed to tap two important aspects of decision-making: risk estimation and feedback processing. We examined how orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and dorsolateral prefrontal cortex (DLPFC) contributed to risk estimation, and how ventrolateral and medial prefrontal cortices (VLPFC and medial PFC) contributed to negative feedback processing in children and adults. Region of interest analyses revealed differences in brain activation between children and adults for ACC and lateral OFC. ACC was recruited more for high-risk than for low-risk trials, and this difference was larger for children than for adults. In contrast, children and adults did not differ in activation for OFC or DLPFC. These data suggest that children's decision-making under uncertainty is associated with a high degree of response conflict. Both age groups exhibited bilateral VLPFC (BA 47) and medial PFC/ACC (BA 6/ BA 32 (dorsal) and 24 (ventral)) activation associated with negative feedback processing. Relative to adults, children engaged lateral OFC more strongly for negative relative to positive feedback. These results indicate that children may find negative feedback more aversive than adults do. In summary, children aged 9-12 years and adults recruit similar brain regions during risk-estimation and feedback processing, but some key differences between the groups provide insight into the factors contributing to developmental changes in decision-making.

Adolescent↗

Alfentanil increases cortical dopamine D2/D3 receptor binding in healthy subjects.

Animal studies have shown that opioids modulate the function of dopaminergic neurons. The effect of alfentanil on cortical and thalamic binding of the D2/D3 receptor ligand [(11)C]FLB 457 was evaluated in eight healthy subjects with positron emission tomography. The simplified reference tissue model was used to calculate tracer binding potential (BP) during a baseline condition and target-controlled infusion of alfentanil, and the results were analyzed using a comparison group not receiving opioid. Behavioral and analgesic effects of alfentanil were also evaluated. In the region-of-interest analysis, alfentanil increased the BP of [(11)C]FLB 457 in the medial frontal cortex (P=0.0027), dorsolateral prefrontal cortex (P=0.027) superior temporal cortex (P=0.028), and medial thalamus (P=0.003) These results were confirmed in a voxel-based analysis, which further revealed an opioid-induced increase in [(11)C]FLB 457 BP in the anterior cingulate cortex (P<0.001). Alfentanil induced euphoria (P=0.003) and analgesia (P=0.006) Cheerfulness (r=0.918, P=0.001) and euphoria (r=0.982, P<0.001) were associated with increased BP of [(11)C]FLB 457 in the left posterior cingulate cortex, but the analgesic effect of alfentanil did not correlate with changes in [(11)C]FLB 457 BP. The results of this study demonstrate opioid-dopamine interactions in frontal and temporal cortical regions and the thalamus in healthy subjects. Increased D2/D3 tracer binding during opioid infusion may reflect decreased synaptic dopamine levels. The association of the uplifting effect of alfentanil with increased D2/D3 binding in the posterior cingulate cortex suggests that cortical dopamine may be involved in the behavioral effects of opioids.

Adult↗

Pathophysiology of obsessive-compulsive disorder: a necessary link between phenomenology, neuropsychology, imagery and physiology.

Obsessive-compulsive disorder (OCD) is characterized by repetitive intrusive thoughts and compulsive time-consuming behaviors classified into three to five distinct symptom dimensions including: (1) aggressive/somatic obsessions with checking compulsions; (2) contamination concerns with washing compulsions; (3) symmetry obsessions with counting/ordering compulsions; (4) hoarding obsessions with collecting compulsions; and (5) sexual/religious concerns. Phenomenologically, OCD could be thought of as the irruption of internal signals centered on the erroneous perception that "something is wrong" in a specific situation. This generates severe anxiety, leading to recurrent behaviors aimed at reducing the emotional tension. In this paper, we examine how the abnormalities in brain activity reported in OCD can be interpreted in the light of physiology after consideration of various approaches (phenomenology, neuropsychology, neuroimmunology and neuroimagery) that contribute to proposing the central role of several cortical and subcortical regions, especially the orbitofrontal cortex (OFC), the anterior cingulate cortex (ACC), the dorsolateral prefrontal cortex (DLPC), the head of the caudate nucleus and the thalamus. The OFC is involved in the significance attributed to the consequences of action, thereby subserving decision-making, whereas the ACC is particularly activated in situations in which there are conflicting options and a high likelihood of making an error. The DLPC plays a critical part in the cognitive processing of relevant information. This cortical information is then integrated by the caudate nucleus, which controls behavioral programs. A dysfunction of these networks at one or several stages will result in the emergence and maintenance of repetitive thoughts and characteristic OCD behavior.

Diagnostic Imaging↗

Regional cerebral blood flow changes associated with interoceptive awareness in the recovery process of anorexia nervosa.

BACKGROUND: An abnormality in regional cerebral blood flow (rCBF) in anorexia nervosa (AN) patients has been reported. There are very few studies that have investigated the rCBF changes in the recovery process of AN. METHODS: For eight female AN patients, we performed (123)I-IMP single photon emission computed tomography (SPECT) and four psychological assessments (Eating Disorder Inventory (EDI), Eating Attitude Test (EAT), Self-Rating Depression Scale (SDS) and State-Trait Anxiety Inventory (STAI)) both before and after inpatient-behavioral therapy. SPECT images were analyzed using statistical parametric mapping software. We also performed correlational analysis between rCBF and clinical variables. RESULTS: Following treatment, the patients showed significant body weight recovery. They showed significant improvement in EAT, SDS, STAI and a subscale of EDI - interoceptive awareness (IA) - but not in total EDI or other EDI subscales. Significant rCBF increases were observed in the precuneus, posterior cingulate cortex (PCC), right dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC) and medial prefrontal cortex (MPFC) by the treatment. Significant correlation was observed between rCBF of right DLPFC and IA score before treatment. CONCLUSIONS: Changes of rCBF in right DLPFC, ACC, MPFC, PCC and precuneus were related to the AN recovery process and might be associated with improvement of IA following treatment.

Adolescent↗

Correlation of PET and qEEG in normal subjects.

Positron emission tomography (PET) and quantitative electroencephalography (qEEG) were obtained in 15 normal male subjects with eyes closed at rest. Correlations between qEEG variables and regional metabolism were examined as an approach to investigating the metabolic and neuroanatomical basis of the generation of the EEG. Analogous to the neurometric approach to qEEG, a normative 2-fluoro-deoxyglucose voxel data base was developed for the PET image. The PET image was transformed to an idealized cylindrical set of coordinates to allow registration with the Talairach stereotactic atlas. PET regions of interest for the thalamus, the left and right temporal lobes, the medial frontal cortex and the dorsolateral prefrontal cortex were defined using Talairach coordinates and correlated to the QEEG. Salient findings included a negative correlation of thalamic metabolism to alpha power and a positive correlation of medial frontal cortical metabolism to delta EEG power. The significance of these findings is discussed with reference to the existing literature on the physiology of the generation of the EEG.

Adult↗

Differential amplitude modulation of auditory evoked cortical potentials associated with brain state in the freely moving rhesus monkey.

We simultaneously recorded auditory evoked potentials (AEP) from the temporal cortex (TCx), the dorsolateral prefrontal cortex (dPFCx) and the parietal cortex (PCx) in the freely moving rhesus monkey to investigate state-dependent changes of the AEP. AEPs obtained during passive wakefulness, active wakefulness (AW), slow wave sleep and rapid-eye-movement sleep (REM) were compared. Results showed that AEP from all three cerebral areas were modulated by brain states. However, the amplitude of AEP from dPFCx and PCx significantly appeared greater attenuation than that from the TCx during AW and REM. These results indicate that the modulation of brain state on AEP from all three cerebral areas investigated is not uniform, which suggests that different cerebral areas have differential functional contributions during sleep-wake cycle.

Animals↗

DNA microarray analysis of functionally discrete human brain regions reveals divergent transcriptional profiles.

Transcriptional profiles within discrete human brain regions are likely to reflect structural and functional specialization. Using DNA microarray technology, this study investigates differences in transcriptional profiles of highly divergent brain regions (the cerebellar cortex and the cerebral cortex) as well as differences between two closely related brain structures (the anterior cingulate cortex and the dorsolateral prefrontal cortex). Replication of this study across three independent laboratories, to address false-positive and false-negative results using microarray technology, is also discussed. We find greater than a thousand transcripts to be differentially expressed between cerebellum and cerebral cortex and very few transcripts to be differentially expressed between the two neocortical regions. We further characterized transcripts that were found to be specifically expressed within brain regions being compared and found that ontological classes representing signal transduction machinery, neurogenesis, synaptic transmission, and transcription factors were most highly represented.

Aged↗

Self-initiated versus externally triggered movements. II. The effect of movement predictability on regional cerebral blood flow.

Event-related potential studies in man suggest a role for the supplementary motor area (SMA) in movement preparation, particularly when movements are internally generated. In a previous study combining PET with recording of movement-related cortical potentials, we found similar SMA activation and early pre-movement negativity during self-initiated and predictably paced index finger extensions. Early pre-movement negativity was absent when finger movements were paced by unpredictable cues. We postulated that preparation preceding self-initiated and predictably cued movements was responsible for equivalent levels of SMA activation in these two conditions. To test this, we have performed further studies on six normal volunteers with H2(15)O-PET. Twelve measurements of regional cerebral blood flow were made in each subject under three conditions: rest; self-initiated right index finger extension at a variable rate of once every 2-7 s; and finger extension triggered by pacing tones at unpredictable intervals (at a rate yoked to the self-initiated movements). Activation associated with these conditions was compared using analysis of covariance and t statistics. Compared with rest, unpredictably cued movements activated the contralateral primary sensorimotor cortex, caudal SMA and contralateral putamen. Self-initiated movements additionally activated rostral SMA, adjacent anterior cingulate cortex and bilateral dorsolateral prefrontal cortex (DLPFC). Direct comparison of the two motor tasks confirmed significantly greater activation of these areas and of caudal SMA in the self-initiated condition. These results, combined with our previous data, suggest that rostral SMA plays a primary role in movement preparation while caudal SMA is a motor executive area. In this experiment and in our earlier study, DLPFC was activated only during the self-initiated task, in which decisions were required about the timing of movements.

Adult↗

Prefrontal regions supporting spontaneous and directed application of verbal learning strategies: evidence from PET.

The prefrontal cortex has been implicated in strategic memory processes, including the ability to use semantic organizational strategies to facilitate episodic learning. An important feature of these strategies is the way they are applied in novel or ambiguous situations-failure to initiate effective strategies spontaneously in unstructured settings is a central cognitive deficit in patients with frontal lobe disorders. The current study examined strategic memory with PET and a verbal encoding paradigm that manipulated semantic organization in three encoding conditions: spontaneous, directed and unrelated. During the spontaneous condition, subjects heard 24 words that were related in four categories but presented in mixed order, and they were not informed of this structure beforehand. Any semantic reorganization was, therefore, initiated spontaneously by the subject. In the directed condition, subjects were given a different list of 24 related words and explicitly instructed to notice relationships and mentally group related words together to improve memory. The unrelated list consisted of 24 unrelated words. Behavioural measures included semantic clustering, which assessed active regrouping of words into semantic categories during free recall. In graded PET contrasts (directed > spontaneous > unrelated), two distinct activations were found in left inferior prefrontal cortex (inferior frontal gyrus) and left dorsolateral prefrontal cortex (middle frontal gyrus), corresponding to levels of semantic clustering observed in the behavioural data. Additional covariate analyses in the first spontaneous condition indicated that blood flow in orbitofrontal cortex (OFC) was strongly correlated with semantic clustering scores during immediate free recall. Thus, blood flow in OFC during encoding predicted which subjects would spontaneously initiate effective strategies during free recall. Our findings indicate that OFC performs an important, and previously unappreciated, role in strategic memory by supporting the early mobilization of effective behavioural strategies in novel or ambiguous situations. Once initiated, lateral regions of left prefrontal cortex control verbal semantic organization.

Acoustic Stimulation↗

Sex-related differences in a gambling task and its neurological correlates.

We investigated sex-related differences in task performance and brain activity in the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC) during performance of a decision-making task (the Iowa Gambling Task). When men and women were examined separately, men activated extensive regions of the right lateral OFC and right DLPFC, as well as the left lateral OFC. In contrast, women activated the left medial OFC. Examining sex differences directly, men showed better task performance and greater lateralized brain activity to the right hemisphere than women. This was exemplified by greater activation in a large area of the right lateral OFC of men during their performance of the Iowa Gambling Task. In contrast, women had greater activation in the left DLPFC, left medial frontal gyrus and temporal lobe during this task. Thus, brain mechanisms engaged by men and women when solving the same decision-making task are different. These observations indicate that sex-related differences contribute to the heterogeneity observed in both normal and abnormal brain functioning. These results also provide further evidence of sexual dimorphism in neurocognitive performance and brain function.

Adult↗

Differential hemodynamic brain activity in schizophrenia patients with blunted affect during quetiapine treatment.

Blood-oxygenation-level-dependent (BOLD) brain changes underlying response to quetiapine were examined using passive viewing of emotionally negative stimuli. Twelve DSM-IV schizophrenia patients with blunted affect (BA+) were scanned before and after 22 weeks of quetiapine treatment. Whole-brain, voxel-based methods were used to assess the differential hemodynamic response to quetiapine. In addition, a post hoc comparison to an independent group of 11 schizophrenia patients without blunted affect (BA-) was performed to compare them with BA+ (postquetiapine) in response to emotion processing. A 22-week treatment with quetiapine resulted in significant clinical improvement in the 12 study completers (mean +/- SD posttreatment PANSS blunted affect score of 5.50 +/- 0.76 at baseline to 2.08 +/- 1.00 at end point; t = 7.78, df = 11, P < 0.0001). Treatment response was associated with significant BOLD changes: increases in prefrontal cortex activation particularly in the right dorsolateral prefrontal cortex (DLPFC, BA 46) and the right anterior cingulate cortex (ACC, BA 32); and in the left putamen, right anterior temporal pole (ATP), and right amygdala. Conversely, before treatment with quetiapine, the same subjects activated the midbrain bilaterally and the right pons. The post hoc conjunctional analyses demonstrated that BA- subjects activated the left ACC, left insula, left ATP (BA 21), left ATP (BA 38), left amygdala, and right medial prefrontal cortex. Quetiapine seems to affect clinical recovery by modulating the functioning of specific brain regions. Unique BOLD changes in the putamen and DLPFC with quetiapine, in the BA+ postquetiapine, may reflect modality-specific effects. Controlled studies are needed to further assess these preliminary findings.

Adult↗

Sex differences in the cerebral BOLD signal response to painful heat stimuli.

There are limited data addressing the question of sex differences in pain-related cerebral processing. This study examined whether pain-related blood oxygenation level-dependent (BOLD) signal change measured with functional magnetic resonance imaging (fMRI) demonstrated sex differences, under conditions of equivalent pain perception. Twenty-eight healthy volunteers (17 women, 11 men) were subject to a fMRI scan while noxious heat stimuli were applied to the dorsum of the left foot. Significant BOLD signal modulation was observed in several nociceptive processing regions of interest (ROIs) in all subjects. There were no sex differences in the spatial extent of BOLD signal change for any ROI, but the signal amplitude was lower for women in most ROIs and significantly so for the primary somatosensory cortex (S1), the midanterior cingulate cortex, and the dorsolateral prefrontal cortex (DLPFC). The BOLD signal response could be positive or negative, and frequently, both polarities were observed within a single ROI. In most ROIs, women show proportionately more voxels with negative signal change than men, and this difference was statistically significant for the S1 and the DLPFC. The time course of the negative signal change was very similar to that of the positive signal change, suggesting that the latter was not "driving" the former. The location of negative and positive clusters formed distinct patterns in several of the ROIs, and these patterns suggest something other than a local "steal" phenomenon as an explanation for the negative signal changes. Sex differences in baseline cerebral blood flow may contribute to the BOLD signal differences observed in this study.

Adult↗

Hemispheric lateralization of somatosensory processing.

Processing of both painful and nonpainful somatosensory information is generally thought to be subserved by brain regions predominantly contralateral to the stimulated body region. However, lesions to right, but not left, posterior parietal cortex have been reported to produce a unilateral tactile neglect syndrome, suggesting that components of somatosensory information are preferentially processed in the right half of the brain. To better characterize right hemispheric lateralization of somatosensory processing, H(2)(15)O positron emission tomography (PET) of cerebral blood flow was used to map brain activation produced by contact thermal stimulation of both the left and right arms of right-handed subjects. To allow direct assessment of the lateralization of activation, left- and right-sided stimuli were delivered during separate PET scans. Both innocuous (35 degrees C) and painful (49 degrees C) stimuli were employed to determine whether lateralized processing occurred in a manner related to perceived pain intensity. Subjects were also scanned during a nonstimulated rest condition to characterize activation that was not related to perceived pain intensity. Pain intensity-dependent and -independent changes in activation were identified in separate multiple regression analyses. Regardless of the side of stimulation, pain intensity--dependent activation was localized to contralateral regions of the primary somatosensory cortex, secondary somatosensory cortex, insular cortex, and bilateral regions of the cerebellum, putamen, thalamus, anterior cingulate cortex, and frontal operculum. No hemispheric lateralization of pain intensity-dependent processing was detected. In sharp contrast, portions of the thalamus, inferior parietal cortex (BA 40), dorsolateral prefrontal cortex (BA 9/46), and dorsal frontal cortex (BA 6) exhibited right lateralized activation during both innocuous and painful stimulation, regardless of the side of stimulation. Thus components of information arising from the body surface are processed, in part, by right lateralized systems analogous to those that process auditory and visual spatial information arising from extrapersonal space. Such right lateralized processing can account for the left somatosensory neglect arising from injury to brain regions within the right cerebral hemisphere.

Adult↗

Evidence for anterior cingulate cortex involvement in monitoring preparatory attentional set.

An important cognitive function underlying unified, voluntary behavior is attentional control. Two frontal regions, anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC), appear to be particularly involved in attentional control and monitoring. In this study, we investigated whether ACC is involved in monitoring the preparatory allocation of attention during task switching, or whether ACC is active only when subjects are processing target stimuli and selecting a response, via a cued-attention design. Event-related BOLD fMRI activity was examined using a cue-target paradigm in which subjects performed task switches that selectively required reallocation of attention when tasks changed. There were three cue conditions: informative switch, informative repeat, and neutral. There were four target conditions: informatively cued switch, informatively cued repeat, neutrally cued switch, and neutrally cued repeat. Significant ACC activity was observed following both informative switch and informative repeat cues, but not after neutral cues. No significant ACC activity was observed following any of the target conditions. Significant DLPFC activity was observed following all three cue conditions and following neutrally cued switch targets. Overall, our results suggest that ACC is involved in monitoring the preparatory allocation of attention for conflict at the level of activation of competing attentional sets. The results also support the role of DLPFC in holding cognitive goals in working memory and allocating attention to the appropriate processing systems to meet those goals.

Adult↗