Search

A growing body of neuroimaging research has documented that, in the absence of an explicit task, the brain shows temporally coherent activity. This so-called 'resting state' activity or, more explicitly, the default-mode network, has been associated with daydreaming, free association, stream of consciousness, or inner rehearsal in humans, but similar patterns have also been found under anesthesia and in monkeys. Spatiotemporal activity patterns in the default-mode network are both complex and consistent, which raises the question whether they are the expression of an interesting cognitive architecture or the consequence of intrinsic network constraints. In numerical simulation, we studied the dynamics of a simplified cortical network using 38 noise-driven (Wilson-Cowan) oscillators, which in isolation remain just below their oscillatory threshold. Time delay coupling based on lengths and strengths of primate corticocortical pathways leads to the emergence of 2 sets of 40-Hz oscillators. The sets showed synchronization that was anticorrelated at

The use of functional neuroimaging on patients with pediatric bipolar disorder finds that there is increased amygdala activation on this group when they are tasked to judge whether emotion in faces showing the same emotion were older or younger than 35 years. The right prefontal systems also seem less engaged in patients with this disorder.

The article discusses the results obtained from a whole-genome study and fine-mapping linkage study that is conducted to analyze the auditory-visual synesthesia, a neurological condition characterized by anomalous sensory perception. The results prove that the disorder is highly linked to various chromosomes, including 2q24, 5q33, 6p12, and 12p12.

Patients with bipolar I disorder demonstrated white matter abnormalities in white matter regions as seen through the use of diffusion tensor imaging. The findings suggest that white matter abnormalities in pediatric bipolar disorder may be useful in constructing neurobiological models of the disorder.

Left-right asymmetry of the brain has been studied mostly through psychological examination and functional imaging in primates, leaving its molecular and synaptic aspects largely unaddressed. Here, we show that hippocampal CA1 pyramidal cell synapses differ in size, shape, and glutamate receptor expression depending on the laterality of presynaptic origin. CA1 synapses receiving neuronal input from the right CA3 pyramidal cells are larger and have more perforated PSD and a GluR1 expression level twice as high as those receiving input from the left CA3. The synaptic density of GluR1 increases as the size of a synapse increases, whereas that of NR2B decreases because of the relatively constant NR2B expression in CA1 regardless of synapse size. Densities of other major glutamate receptor subunits show no correlation with synapse size, thus resulting in higher net expression in synapses having right input. Our study demonstrates universal left-right asymmetry of hippocampal synapses with a fundamental relationship between synaptic area and the expression of glutamate receptor subunits. hippocampus | laterality | NMDA receptor | AMPA receptor | spine

The use of cognitive neuroscience and functional brain neuroimaging to understand brain dysfunction in pediatric psychiatric disorders is discussed. Results show that bipolar youths demonstrate impairment in affective and cognitive neural systems and in these two circuits' interface. Implications for the diagnosis and treatment of psychiatric disorders are also examined.

Neuroimaging findings support the frontal-striatal-thalamic model of pediatric obsessive-compulsive disorder. Glutamate is also implicated in the pathological finding of the disease. Implications for pediatric OCD treatments are discussed.

Event-related potential is a kind of neuroimaging tool which can be used in the study of neurodevelopment. Two areas of atypical development, children diagnosed with autism and children experiencing early psychosocial neglect, have benefited from ERPs. The physiological basis of ERPs and the constraints on their applications are also discussed.

Neuroimaging findings which identify n ormal brain development trajectories are presented. Results show that early brain development begins with the neural tube formation and ends with myelintation. How disturbances in brain development patterns are related to childhood psychiatric disorders is examined.

The use of longitudinal neuroimaging to study the developmental perspectives of brain pathology in children with childhood-onset schizophrenia (COS) is described. Structural neuroimaging is capable of providing evidence of neurobiological specificity of COS to distinguish it from other brain abnormalities seen in neuropsychiatric illnesses like pediatric bipolar illness, which exhibit similar clinical symptoms.

A short-term source monitoring procedure with functional magnetic resonance imaging assessed neural activity when participants made judgments about the format of 1 of 4 studied items (picture, word), the encoding task performed (cost, place), or whether an item was old or new. The results support findings from long-term memory studies showing that left anterior ventrolateral prefrontal cortex (PFC) is engaged when people make source attributions about reflectively generated information (cognitive operations, conceptual features). The findings also point to a role for right lateral PFC in attention to perceptual features and/or familiarity in making source decisions. Activity in posterior regions also differed depending on what was evaluated. These results provide neuroimaging evidence for theoretical approaches emphasizing that agendas influence which features are monitored during remembering (e.g., M. K. Johnson, S. Hashtroudi, & D. S. Lindsay, 1993). They also support the hypothesis that some of the activity in left lateral PFC and posterior regions associated with remembering specific information is not unique to long-term memory but rather is associated with agenda-driven source monitoring processes common to working memory and long-term memory. Keywords: source memory, source monitoring, fMRI, ventrolateral prefrontal cortex

Performance on tests of source memory is typically based on recollection of contextual information associated with an item. However, recent neuroimaging results have suggested that the perirhinal cortex, a region thought to support familiarity-based item recognition, may support source attributions if source information is encoded as a feature of the relevant item (i.e., 'unitized'). The authors hypothesized that familiarity may contribute to source memory performance if item and source information are unitized during encoding, whereas performance may rely more heavily on recollection if source information is encoded as an arbitrary contextual association. Three source recognition experiments examining receiver operating characteristics and response deadline performance indicated that familiarity makes a greater contribution to source memory if source and item information are unitized during encoding. These findings suggest that familiarity can contribute to source recognition and that its contribution depends critically on the way item and source information are initially processed. Keywords: source memory, familiarity, unitization, recollection, ROCs

Embodiment theory proposes that neural systems for perception and action are also engaged during language comprehension. Previous neuroimaging and neurophysiological studies have only been able to demonstrate modulation of action systems during comprehension of concrete language. We provide neurophysiological evidence for modulation of motor system activity during the comprehension of both concrete and abstract language. In Experiment 1, when the described direction of object transfer or information transfer (e.g., away from the reader to another) matched the literal direction of a hand movement used to make a response, speed of responding was faster than when the two directions mismatched (an action-sentence compatibility effect). In Experiment 2, we used single-pulse transcranial magnetic stimulation to study changes in the corticospinal motor pathways to hand muscles while reading the same sentences. Relative to sentences that do not describe transfer, there is greater modulation of activity in the hand muscles when reading sentences describing transfer of both concrete objects and abstract information. These findings are discussed in relation to the human mirror neuron system. Keywords: Language; Embodiment; Abstraction; Mirror neurons; TMS.

It is hypothesized that emotional arousal modulates long-term memory consolidation through the amygdala. Gaseous anesthetic agents are among the most potent drugs that cause temporary amnesia, yet the effects of inhalational anesthesia on human emotional memory processing remain unknown. To study this, two experiments were performed with the commonly used inhalational anesthetic sevoflurane. In experiment 1, volunteers responded to a series of emotional and neutral slides while under various subanesthetic doses of sevoflurane or placebo (no anesthesia). One week later, a mnemonic boost for emotionally arousing stimuli was evident in the placebo, 0.1%, and 0.2% sevoflurane groups, as measured with a recognition test. However, the mnemonic boost was absent in subjects who received 0.25% sevoflurane. Subsequently, in experiment 2, glucose PET assessed brain-state-related activity of subjects exposed to 0.25% sevoflurane. Structural equation modeling of the PET data revealed that 0.25% sevoflurane suppressed amygdala to hippocampal effective connectivity. The behavioral results show that 0.25% sevoflurane blocks emotional memory, and connectivity results demonstrate that this dose of sevoflurane suppresses the effective influence of the amygdala. Collectively, the findings support the hypothesis that the amygdala mediates memory modulation by demonstrating that suppressed amygdala effectiveness equates with a loss of emotional memory. arnygdala | anesthesia | brain imaging | cerebral metabolism | sevoflurane

The role of unconscious thought processes is examined to analyze economic decision-making. Psychoanalytic research and neuroimaging reveal examples of brain function, which are not under conscious control, modulating decision-making. The role of emotions and the unconscious in decision-making and human behavior is discussed.

Byline: A. May (1) Keywords: Migraine; Cluster headache; Pain; Functional imaging; PET; MRI; VBM Abstract: The neuroimaging of headache patients has revolutionised our understanding of the pathophysiology of primary headaches and provided unique insights into these syndromes. Modern imaging studies point, together with the clinical picture, towards a central triggering cause. The early functional imaging work using positron emission tomography shed light on the genesis of some syndromes, and has recently been refined, implying that the observed activation in migraine (brainstem) and in several trigeminal-autonomic headaches (hypothalamic grey) is involved in the pain process in either a permissive or triggering manner rather than simply as a response to first-division nociception per se. Using the advanced method of voxel-based morphometry, it has been suggested that there is a correlation between the brain area activated specifically in acute cluster headache -- the posterior hypothalamic grey matter -- and an increase in grey matter in the same region. No structural changes have been found for migraine and medication overuse headache, whereas patients with chronic tension-type headache demonstrated a significant grey matter decrease in regions known to be involved in pain processing. Modern neuroimaging thus clearly suggests that most primary headache syndromes are predominantly driven from the brain, activating the trigeminovascular reflex and needing therapeutics that act on both sides: centrally and peripherally. Author Affiliation: (1) Department of Systems Neuroscience, Universitats-Krankenhaus Eppendorf (UKE), Martinistr. 52, D-20246, Hamburg, Germany Article History: Registration Date: 01/01/2006 Received Date: 24/05/2006 Accepted Date: 06/06/2006 Online Date: 11/08/2006

Introduction Recent research has suggested that air pollution is a risk factor for dementia, mild cognitive disorders, and cognitive decline (Chen et al. 2017; Power et al. 2011, 2016; Tzivian [...], Background: Only a limited number of neuroimaging studies have explored the effects of ambient air pollution in adults. The prior studies have investigated only cortical volume, and they have reported mixed findings, particularly for gray matter. Furthermore, the association between nitrogen dioxide (N[O.sub.2]) and neuroimaging markers has been little studied in adults. Objectives: We investigated the association between long-term exposure to air pollutants (N[O.sub.2], particulate matter (PM) with aerodynamic diameters of [less than or equal to] 10 [micro]m (PM10) and [less than or equal to] 2.5 [micro]m (PM2.5), and neuroimaging markers. Methods: The study included 427 men and 530 women dwelling in four cities in the Republic of Korea. Long-term concentrations of PM10, N[O.sub.2], and PM2.5 at residential addresses were estimated. Neuroimaging markers (cortical thickness and subcortical volume) were obtained from brain magnetic resonance images. A generalized linear model was used, adjusting for potential confounders. Results: A 10-[micro]g/[m.sup.3] increase in PM10 was associated with reduced thicknesses in the frontal [-0.02 mm (95% CI: -0.03, -0.01)] and temporal lobes [-0.06 mm (95% CI: -0.07, -0.04)]. A 10-[micro]g/[m.sup.3] increase in PM2.5 was associated with a thinner temporal cortex [-0.18 mm (95% CI: -0.27, -0.08)]. A 10-ppb increase in N[O.sub.2] was associated with reduced thicknesses in the global [-0.01 mm (95% CI: -0.01, 0.00)], frontal [-0.02 mm (95% CI: -0.03, -0.01)], parietal [-0.02 mm (95% CI: -0.03, -0.01)], temporal [-0.04 mm (95% CI: -0.05, -0.03)], and insular lobes [-0.01 mm (95% CI: -0.02, 0.00)]. The air pollutants were also associated with increased thicknesses in the occipital and cingulate lobes. Subcortical structures associated with the air pollutants included the thalamus, caudate, pallidum, hippocampus, amygdala, and nucleus accumbens. Discussion: The findings suggest that long-term exposure to high ambient air pollution may lead to cortical thinning and reduced subcortical volume in adults.