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At least 865 records · Page 48Linked to original sources

PubMed2002

Project for a scientific psychiatry in the 21st century.

OBJECTIVE: To discuss potential advances in neuroscientific knowledge in the 21st century, enabling the realization of Freud's original vision of a basic biological science and an associated metapsychology. RESULTS: The Australian Twin Study of Attention Deficit Hyperactivity Disorder (ADHD) has demonstrated the high heritability of the core symptoms of ADHD, as well as showing important genetic and environmental influences on comorbid conditions. Brain mapping techniques suggest that working memory, as measured by an A-X Continuous Performance Task, is important in ADHD. METHODS: To outline the development of our own clinical research into ADHD, and the potential for future behaviour and molecular genetic approaches. CONCLUSIONS: The 21st century promises new and exciting developments in phenomenology, genetics, and neuroscientific understandings in Child Psychiatry.

Attention Deficit Disorder with Hyperactivity↗

PubMedDate not supplied

[The evoked cortical activity of the cerebral hemispheres in man during the active and passive perception of facial expression].

Twenty-two right-handed subjects were asked either to identify sad, neutral, or laughing faces presented on a computer monitor or to view passively the same pictures without classification. Visual evoked potentials were recorded from F3/4, C3/4, P3/4, O1/2, and T5/6 derivations. In comparison with the passive viewing, the emotion recognition was characterized by the higher level of cortical activity reflected in the higher N1, N2, N3 amplitudes and shortened latencies of N1, P2, and N2 waves. In contrast, the latencies of the later P3 and N3 waves were longer. During emotion recognition, the dynamical brain mapping technique revealed symmetrical activation of the frontocentral areas and only the right-side activation during the passive perception. Factor analysis demonstrated a complication of N2 structure in the task of face emotion recognition. A principal component corresponding to the descending part of the N2 wave was revealed, which probably reflected the stage of image classification.

Adult↗

PubMedDate not supplied

[The negative components of visual evoked potentials in the mechanisms of the classification of incomplete images].

Event-related brain potentials were recorded in 16 young adult subjects in response to a short presentation of recognizable and nonrecognizable visual images with an incomplete set of signs. Sequential brain maps and amplitude-temporal ERP parameters in 1000 ms poststimulus epoch were estimated (BMDP 4M and 7M, 1987). The results suggested that the component N450 was specifically related to a perception of nonrecognizable visual images. N70 and N150 reflected voluntary attention during invariant recognition and the late negative waves (600-1000 ms) reflected an "exhaustive search" for categorization of new information.

Adult↗

PubMedDate not supplied

[The physiological indices of pre-examination stress].

The EEG spectral power characteristics and intracortical interactions were studied using brain mapping technique in students selected by their high level of anxiety and predisposition to stress. Before the examination, the activation of the anterior areas of the right hemisphere was higher than in norm by both indices. After the examination, the activation of these areas decreased. The obtained results, probably, reflect the neurophysiological dynamics of psychoemotional stress.

Adjustment Disorders↗

PubMed1999

Positron emission tomography in pediatric neurology.

Positron emission tomography (PET) is an accurate and relatively noninvasive way of studying brain activity using systemically administered tracers labeled with positron emitting isotopes. In pediatric neurology, it has great scope not only to elucidate the complexities of the developing brain but also to understand disease processes and characterize biological risk factors. Its greatest clinical utility lies in the field of epilepsy where it is used (in patients with intractable partial epilepsy) to localize epileptogenic foci for surgical resection. In addition, functional brain mapping using PET is increasingly being used to reliably and accurately identify speech and sensory-motor areas to minimize postoperative morbidity. PET is also useful in evaluating neurodegenerative disorders and cognitive abnormalities when magnetic resonance imaging scans are unrevealing. The technology continues to progress rapidly through improvements in imaging and radiopharmacology with potential applications in neurooncology, cerebral vascular disease, and metabolic diseases.

Brain↗

PubMed2005

Abnormalities of hippocampal surface structure in very mild dementia of the Alzheimer type.

To better define the pattern of hippocampal deformity early in the course of Alzheimer's disease, we compared the pattern of hippocampal surface variation in subjects with very mild dementia of the Alzheimer type (DAT) and nondemented subjects. The surface of the hippocampus was divided a priori on a neuroanatomical template into three zones approximating the locations of underlying subfields [Csernansky, J.G., Wang, L., Swank, J., Miller, J.P., Gado, M., McKeel, D., Miller, M.I., Morris, J.C., 2005. Preclinical detection of Alzheimer's disease: hippocampal shape and volume predict dementia onset in the elderly. NeuroImage 25, 783--792]; i.e., a lateral zone (LZ) approximating the CA1 subfield, a superior zone (SZ) approximating the combined CA2, CA3, CA4 subfields and the gyrus dentatus (GD), and an inferior-medial zone (IMZ) approximating the subiculum. Large-deformation high-dimensional brain mapping (HDBM-LD) was used to generate the hippocampal surfaces of all subjects and to register the surface zones across subjects. Average variations within each zone were calculated for the subjects with very mild DAT as compared to the average of the nondemented subjects. After correcting for multiple comparisons, the very mild DAT subjects showed significant inward variation in the left and right LZ, the left and right IMZ, but not in the left and right SZ as compared to nondemented subjects. In logistic regression analyses, inward variation of the left and right LZ or IMZ by 0.1 mm relative to the average of the nondemented subjects increased the odds of the subject being a very mild DAT subject (range-1.18 to 1.57) rather than being a nondemented subject. The odds ratios for the left and right SZ were not significant. These results represent a replication of our previous findings [Csernansky, J.G., Wang, L., Joshi, S., Miller, J.P., Gado, M., Kido, D., McKeel, D., Morris, J.C., Miller, M.I., 2000. Early DAT is distinguished from aging by high-dimensional mapping of the hippocampus. Neurology 55, 1636--1643.] and suggest that inward deformities of the hippocampal surface in proximity to the CA1 subfield and subiculum can be used to distinguish subjects with very mild DAT from nondemented subjects.

Activities of Daily Living↗

PubMed1998

The "Mozart effect" on epileptiform activity.

The "Mozart Effect," using the Piano Sonata in D Major (K.448), was examined in patients with seizures. In 23 of 29 instances significant decreases in epileptiform activity were noted from patients even in coma, with status epilepticus or with periodic lateralized epileptiform discharges (PLEDs). The effect may be immediate or require 40-300 sec to manifest itself. The change in the amount of ictal activity in one patient in coma was from 62% before the music to 21% during Mozart. Amplitudes of these discharges also have often decreased. Examples of PLEDs on both temporal areas are shown in which the effect was only on the left temporal area but in other patients only on the right temporal area. Brain maps during the music showed theta and alpha activity decreased on the central areas, while delta waves increased on the frontal midline area. The basis of this effect is likely that the superorganization of the cerebral cortex with its highly structured radial columns seen throughout both hemispheres may resonate with the superior architecture of Mozart's music.

Adolescent↗

PubMed1999

Increased cortical oxidative metabolism due to sensory stimulation: implications for functional brain imaging.

Modern functional brain mapping relies on interactions of neuronal electrical activity with the cortical microcirculation. The existence of a highly localized, stimulus-evoked initial deoxygenation has remained a controversy. Here, the activity-dependent oxygen tension changes in the microcirculation were measured directly, using oxygen-dependent phosphorescence quenching of an exogenous indicator. The first event after sensory stimulation was an increase in oxygen consumption, followed by an increase in blood flow. Because oxygen consumption and neuronal activity are colocalized but the delayed blood flow is not, functional magnetic resonance imaging focused on this initial phase will yield much higher spatial resolution, ultimately enabling the noninvasive visualization of fundamental processing modules in the human brain.

Animals↗

PubMed1989

An example of the possible clinical usefulness of topographic EEG displays.

This paper shows the brain maps of a patient before and during a seizure initiated by a focus within the right occipital area. The maps demonstrate an ictal transformation in the form of a gradual decrease in frequency of the ictal rhythms, seen also on the EEG traces. However, the maps also show the very distinct difference in the background activity between the left and right hemispheres, and also the possibility of independent foci of depressed activity within the right anterior and posterior temporal areas, the latter not at all evident on the EEG tracings. This case may serve as an example of useful data gathered on a patient by EEG topography, not made clear by a standard recording.

Adolescent↗

PubMed1992

Therapeutic efficacy of pyritinol in patients with senile dementia of the Alzheimer type (SDAT) and multi-infarct dementia (MID).

This trial was performed to investigate the efficacy of pyritinol in the treatment of senile dementia. Initially, a total of 183 inpatients were screened for eligibility. Of 164 patients who met the inclusion criteria, 156 completed the trial. Allocation of the patients to the Senile Dementia of the Alzheimer Type group or the Multi-Infarct Dementia group was based on the Hachinski Ischemic Score, computed tomography scans and electroencephalographic (EEG) findings. In a 12-week double-blind treatment phase either 200 mg pyritinol dihydrochloride-monohydrate or placebo was given 3 times daily. Confirmatory statistics included item 2 of the Clinical Global Impression, the total score of the Short Cognitive Performance Test (Syndrom Kurz Test) and the factor 'cognitive disturbances' of the Sandoz Clinical Assessment Geriatric scale. In addition, data on tolerance, of EEG brain mapping and of a responder analysis were evaluated based on descriptive statistics. The therapeutic efficacy of pyritinol was clearly demonstrated by confirmatory analysis as the drug was statistically significantly superior to placebo in all 3 target variables. The clinical relevance of the outcome was underlined by the analysis of the descriptive variables and by the convergence found at the different observation levels. The EEG mapping demonstrated significant differences between placebo and pyritinol, with the latter decreasing slow and increasing fast alpha and beta activity, which reflects improvement of vigilance. Based on the results of this trial, it can be accepted that the therapeutic effect of pyritinol is superior to placebo in patients with mild to moderate dementia of both degenerative and vascular etiology.

Aged↗

PubMed2000

Spatiotemporal dynamics of the BOLD fMRI signals: toward mapping submillimeter cortical columns using the early negative response.

The existence of the early-negative blood-oxygenation-level-dependent (BOLD) response is controversial and its practical utility for mapping brain functions with columnar spatial specificity remains questionable. To address these issues, gradient-echo BOLD fMRI studies were performed at 4.7 T and 9.4 T using the well-established orientation column model in the cat visual cortex. A robust transient early-negative BOLD response was consistently observed in anesthetized cat (-0.35 +/- 0.09%, mean +/- SD, n = 8 at 2.9 +/- 0.5 sec poststimulus onset for 4.7 T, TE = 31 ms; -0.29 +/- 0.10%, n = 4 at 3.0 +/- 0.8 sec poststimulus onset for 9.4 T, TE = 12 ms). In addition to its temporal evolution, the BOLD response also evolved dynamically in the spatial domain. The initially spatially localized early-negative signal appeared to dynamically drain from the active sites toward large vessels, followed by a wave of the delayed positive signal, which exhibited similar spatiotemporal dynamics. Only the early-negative BOLD response within 2 sec of the stimulus onset (not the entire dip) yielded columnar layouts without differential subtraction. The functional maps of two orthogonal orientations using the first 2-sec dip were indeed complementary. On the other hand, the delayed positive BOLD response appeared diffused and extended beyond the active sites. It was thus less suitable to resolve columnar layouts. These results have implications for the design and interpretation of the BOLD fMRI at columnar resolution. Magn Reson Med 44:231-242, 2000.

Animals↗

PubMed1984

Dyslexia: two priorities for the 1980s.

Within the past decade significant advances have been made in articulating the unique neuropsychological and cognitive processes in dyslexic children. The brain mapping procedures and postmortum studies are especially important in this regard. However, two important issues remain largely unaddressed. First, to date, no recognized nosology for dyslexia or subtypes of dyslexia exist. Second, the functional neurolinguistic system involved in reading and severe reading failure is, as of yet, still not completely understood in regard to subtypes of dyslexia. This article discusses these two areas of priority and proposes a framework for addressing these areas of concern.

Brain↗

PubMed1989

Effects of L-tryptophan on daytime arousal.

A double-blind placebo-controlled study was carried out on 20 subjects to examine the early morning sedative effects of 2 g of L-tryptophan. Using brain mapping technique, 16-channel EEG recordings were topographically displayed. A distinct increase in theta amplitude, predominantly in the central region, together with an alpha reduction was observed after L-tryptophan administration, signs characterizing the EEG of drowsiness. Subjective self-rated sleepiness increased after the ingestion of L-tryptophan. Psychomotor performance, assessed by means of various psychometric tests, was not affected by this low dose of L-tryptophan.

Adult↗

PubMed2005

Source density-driven independent component analysis approach for fMRI data.

Independent component analysis (ICA) has become a popular tool for functional magnetic resonance imaging (fMRI) data analysis. Conventional ICA algorithms including Infomax and FAST-ICA algorithms employ the underlying assumption that data can be decomposed into statistically independent sources and implicitly model the probability density functions of the underlying sources as highly kurtotic or symmetric. When source data violate these assumptions (e.g., are asymmetric), however, conventional ICA methods might not work well. As a result, modeling of the underlying sources becomes an important issue for ICA applications. We propose a source density-driven ICA (SD-ICA) method. The SD-ICA algorithm involves a two-step procedure. It uses a conventional ICA algorithm to obtain initial independent source estimates for the first-step and then, using a kernel estimator technique, the source density is calculated. A refitted nonlinear function is used for each source at the second step. We show that the proposed SD-ICA algorithm provides flexible source adaptivity and improves ICA performance. On SD-ICA application to fMRI signals, the physiologic meaningful components (e.g., activated regions) of fMRI signals are governed typically by a small percentage of the whole-brain map on a task-related activation. Extra prior information (using a skewed-weighted distribution transformation) is thus additionally applied to the algorithm for the regions of interest of data (e.g., visual activated regions) to emphasize the importance of the tail part of the distribution. Our experimental results show that the source density-driven ICA method can improve performance further by incorporating some a priori information into ICA analysis of fMRI signals.

Adult↗

PubMed1991

Brain imaging: evoked potential, quantitative EEG and SPECT abnormalities in schizophrenia.

The case of a nineteen-year-old female with a three-year history of psychiatric symptomatology clinically consistent with the DSM-III-R diagnosis of schizophrenia is presented. Neurophysiologic assessment using topographic brain mapping demonstrated auditory evoked potential P300 asymmetry with left temporal inactivation and increased latency, while EEG frequency analysis was remarkable for left hemispheric slow wave predominance as well as increased left temporal beta activity. Single photon emission computed tomography (SPECT) using hexamethylpropyleneamine oxime (HMPAO) in the same patient revealed radionucleide uptake reductions in the frontotemporal cortical regions. The clinical presentation of schizophrenia in the context of these imaging correlations is reviewed.

Adult↗

PubMed1992

The neuroanatomical basis of anxiety.

This review details the neural systems that are important in anxiety-related behaviours. In particular, the role of the amygdaloid complex, Papez circuit, septohippocampal formation and raphe nuclei are described and discussed. Evidence is gathered from a variety of experimental approaches. These include behavioural assessment of anxiety in animals after intracerebral injection of pharmacological agents and following lesions of discrete brain nuclei and selective neurotransmitter pathways. Further evidence is provided by functional brain mapping studies applied to animals and humans. It is proposed that the neural systems recruited in different experimental conditions of anxiety may differ, supporting the notion that clinical anxiety exists in several forms. This has implications for the identification of new anxiolytic treatments. In particular, the findings suggest that approaches aimed at identifying new anxiolytic agents must take into account both the distribution of receptors for the drug and the neuronal systems activated by the experimental protocol.

Animals↗

PubMed2001

Interdependencies in the spontaneous EEG while listening to music.

We studied the patterns of interdependency between different brain regions during the performance of higher cognitive functions. Our goal was to check the existence in these patterns of both task-related differences (e.g. listening to music vs. rest) and training-related differences (musicians vs. non-musicians). For this purpose, a non-linear measure, called similarity index (S.I.), was used to detect asymmetric interdependencies between different brain regions by means of EEG signals. Relatively active and passive regions of the brain were found where the degree of activity was represented by excited degrees of freedom. The S.I. obtained during listening to different kinds of music was compared statistically with the S.I. with eyes closed, and significant changes (P< or = 0.05) were entered into schematic brain maps. A topographical representation of the S.I. yielded differences in the interdependency while performing different cognitive tasks. The results demonstrate the occurrence of task-related differences in both groups of subjects. Furthermore, subjects with musical training possessed significantly higher degrees of interdependencies than such without musical training while listening to music but not to text. We conclude that the new measure can be successfully applied for studying the dynamical co-operation between cortical areas during higher cognitive functioning.

Adult↗

PubMed2004

[The visual pathways, from anatomical MRI to physiological with (f)MRI and tractography with diffusion tensor MRI (DTMRI)].

Advances in MRI technology have led to a better knowledge of visual pathways (1984-2004), with a new descriptive anatomy and functional model. The authors first describe the technical development of MRI over the last thirty years, then describe and illustrate the new descriptive anatomy. Cephalic MRI reveals brain structures that were previously invisible, on different encephalic planes, in the optic pathways, horizontally from the cornea to the calcarin fissure (neuro-ocular plane (NOP), oblique trans-hemispheric neuro-ocular (OTNOP) and neuro-opto-tractal planes (NOTP)), in their orthogonal orientation upon the oculomotor pathways: head and axonal optic nerve pack (visual deutoneurons in their meninges), optic tracts, lateral geniculate bodies, optic radiations and the calcarian fissure. Comparative anatomy with the rhesus macaque is mentioned. Functional neuroanatomy (physiology) benefits from cine-MRI for ocular motricity (OD MRI), growth by the observation of myelinization in children, blood and CSF circulation by MR angiography, local blood volumes by perfusion imaging, neuronal quantification with inflammation or myelin regeneration by spectroscopy (MRS), brain mapping by functional MR ((f)MRI) measuring local CBF enhancement by paradigmatic stimulations. The recent functional imaging method, tractography (or diffusion tensor MRI (DTMRI)), using diffusion MRI techniques, natural vector calculations with diffusion tensor and software power for morphological and statistical directional results, represents the direction of projection, association and commissural white matter tracts. Normal examples are shown and some common clinical consequences are discussed.

Adult↗