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Astronomia nova to human brain mapping.
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[Magnetoencephalography (MEG) and functional brain mapping].
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A probabilistic atlas and reference system for the human brain: International Consortium for Brain Mapping (ICBM).
Motivated by the vast amount of information that is rapidly accumulating about the human brain in digital form, we embarked upon a program in 1992 to develop a four-dimensional probabilistic atlas and reference system for the human brain. Through an International Consortium for Brain Mapping (ICBM) a dataset is being collected that includes 7000 subjects between the ages of eighteen and ninety years and including 342 mono- and dizygotic twins. Data on each subject includes detailed demographic, clinical, behavioural and imaging information. DNA has been collected for genotyping from 5800 subjects. A component of the programme uses post-mortem tissue to determine the probabilistic distribution of microscopic cyto- and chemoarchitectural regions in the human brain. This, combined with macroscopic information about structure and function derived from subjects in vivo, provides the first large scale opportunity to gain meaningful insights into the concordance or discordance in micro- and macroscopic structure and function. The philosophy, strategy, algorithm development, data acquisition techniques and validation methods are described in this report along with database structures. Examples of results are described for the normal adult human brain as well as examples in patients with Alzheimer's disease and multiple sclerosis. The ability to quantify the variance of the human brain as a function of age in a large population of subjects for whom data is also available about their genetic composition and behaviour will allow for the first assessment of cerebral genotype-phenotype-behavioural correlations in humans to take place in a population this large. This approach and its application should provide new insights and opportunities for investigators interested in basic neuroscience, clinical diagnostics and the evaluation of neuropsychiatric disorders in patients.
Brain mapping: new wave optical imaging.
Optical imaging of intrinsic signals is widely used for high-resolution brain mapping in various animal species. A new approach using continuous data acquisition and Fourier decomposition of the signal allows for much faster mapping, opening up the possibility of applying this method to new experimental questions.
Topographic brain mapping of EEG after acute application of ergotalkaloids in the elderly.
In a double-blind, placebo-controlled, crossover study the encephalotropic and nootropic effects of single doses of two ergotalkaloids (30 and 60 mg nicergoline and 5 mg co-dergocrine mesylate (CDM)) were investigated in 12 elderly subjects (mean age 67 years), utilizing topographic brain mapping of the EEG. Evaluation of EEG, memory, pulse and blood pressure were carried out at 0, 2, 4, 6 and 8 h. Topographic brain maps demonstrated an augmentation of total power, an acceleration of the centroid of the total activity, a decrease of delta/theta and an increase of beta activity (mostly in the alpha-adjacent frequency bands), as well as an acceleration of the centroid of the delta/theta and a slowing of the beta centroid. These changes are indicative of improvement in vigilance of elderly subjects after ergotalkaloids, which was also reflected in the significant improvement of memory after nicergoline. Topographically, the main effect was found over the frontal, central and temporal regions. Timewise, the pharmacodynamic peak fell into the 4th h, although with 60 mg significant encephalotropic effects could be observed in the 2nd and in the 6th h. The drugs were well tolerated.
Brain mapping for hemispheric tumors in children.
Hemispheric tumors are common in children. Pathologically, they range from indolent low grade astrocytic tumors to high grade malignant neoplasms. In general, the extent of resection correlates favorably with survival. Advances in technology are permitting surgical resection to be extended to near eloquent and eloquent regions of the brain. These techniques include advanced neuronavigation, brain mapping, and intra-operative MRI scanners. Incorporation of functional information in surgical planning should lead to safer surgical procedures with improvements in patient outcome.
Mapping brain maturation and cognitive development during adolescence.
Non-invasive mapping of brain structure and function with magnetic resonance imaging (MRI) has opened up unprecedented opportunities for studying the neural substrates underlying cognitive development. There is an emerging consensus of a continuous increase throughout adolescence in the volume of white matter, both global and local. There is less agreement on the meaning of asynchronous age-related decreases in the volume of grey matter in different cortical regions; these might equally represent loss ("pruning") or gain (intra-cortical myelination) of tissue. Functional MRI studies have so far focused mostly on executive functions, such as working memory and behavioural inhibition, with very few addressing questions regarding the maturation of social cognition. Future directions for research in this area are discussed in the context of processing biological motion and matching perceptions and actions.
Three-dimensional probabilistic anatomical cranio-cerebral correlation via the international 10-20 system oriented for transcranial functional brain mapping.
The recent advent of multichannel near-infrared spectroscopy (NIRS) has expanded its technical potential for human brain mapping. However, NIRS measurement has a technical drawback in that it measures cortical activities from the head surface without anatomical information of the object to be measured. This problem is also found in transcranial magnetic stimulation (TMS) that transcranially activates or inactivates the cortical surface. To overcome this drawback, we examined cranio-cerebral correlation using magnetic resonance imaging (MRI) via the guidance of the international 10-20 system for electrode placement, which had originally been developed for electroencephalography. We projected the 10-20 standard cranial positions over the cerebral cortical surface. After examining the cranio-cerebral correspondence for 17 healthy adults, we normalized the 10-20 cortical projection points of the subjects to the standard Montreal Neurological Institute (MNI) and Talairach stereotactic coordinates and obtained their probabilistic distributions. We also expressed the anatomical structures for the 10-20 cortical projection points probabilistically. Next, we examined the distance between the cortical surface and the head surface along the scalp and created a cortical surface depth map. We found that the locations of 10-20 cortical projection points in the standard MNI or Talairach space could be estimated with an average standard deviation of 8 mm. This study provided an initial step toward establishing a three-dimensional probabilistic anatomical platform that enables intra- and intermodal comparisons of NIRS and TMS brain imaging data.
[Functional brain mapping for neurosurgery].
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[Localization of the epileptogenic focus in a case of xantho- astrocytoma of the temporal lobe by brain mapping].
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Implementation of three-dimensional EEG brain mapping.
The electroencephalogram (EEG) visualization software was developed containing two-dimensional (2D) and three-dimensional (3D) brain mapping modules. The input to the program is standard clinical individual patient data recorded using digital EEG and magnetic resonance imaging (MRI). The software utilizes several techniques, such as heuristic triangulation, ray casting, Gouraud shading, and image fusion to form multimodal 3D images. The program has been applied to the 3D visualization of various EEG signals, "cortical" EEG signals, and potential fields generated by a computer model. The developed program appears to operate efficiently and intuitively in PC/Windows environment.
Topographic analysis in brain mapping can be compromised by the average reference.
The average reference introduces ghost potential fields at the latencies for which the integral of scalp-recorded potentials differs from zero. These spurious effects occur because the average reference is computed from a limited number of (scalp) electrodes which do not survey the bottom half of the head. By arbitrarily re-setting the zero at each latency in the maps to be compared, it can also obliterate or even reverse topographical differences in the case of focal brain potentials enhancements thereby defeating the purpose of brain mapping.
Brain mapping in sedated infants and young children with passive-functional magnetic resonance imaging.
Functional magnetic resonance imaging (fMRI) in pediatric patients presents a unique set of problems due to the need for patient compliance, the frequent need for sedation and an early developmental status. A new method for using fMRI in sedated infants and young children is presented using passive stimuli focused on visual, sensorimotor and language functions. All of these stimuli are presented such that no patient interaction is required. Eight sedated children undergoing diagnostic MRI scans of the brain participated in these passive fMRI procedures. Cortical regions were identified using standard techniques applied to the blood-oxygen-level-dependent signal which is the basis for fMRI. The results support the feasibility of brain mapping in sedated children with passive fMRI techniques.
History and future directions of human brain mapping and functional neuroimaging.
It has long been known that there is some degree of localisation of function in the human brain, as indicated by the effects of traumatic head injury. Work in the middle of the 20th century, notably the direct cortical stimulation of patients during neurosurgery, suggested that the degree and specificity of such localisation of function were far greater than had earlier been imagined. One problem with the data based on lesions and direct stimulation was that the work depended on the study of what were, by definition, damaged brains. During the second half of the 20th century, a collection of relatively non-invasive tools for assessing and localising human brain function in healthy volunteers has led to an explosion of research in what is often termed "Brain Mapping". The present article reviews some of the history associated with these tools, but emphasises the current state of development with speculation about the future.
Alpha rhythm power and the effect of photic stimulation in migraine with brain mapping.
The topographic maps of 50 patients suffering from migraine with or without aura were compared to the brain maps of 20 normal controls and 20 patients with tension-type headaches. Only the migraine group showed a significant decrement of alpha rhythm power, during rest with eyes closed, at the posterior areas of the brain, and a significant increment of alpha power at the same regions during IPS at 20 c/sec.
Correlation of brain mapping and MR imaging.
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Eye movements on brain maps.
This report shows that eye movement artifact, either in the form of up-down or side to side movements, can be clearly demonstrated on brain maps by carefully adjusting the gain in order to delineate the distribution of activity on the anterior regions. Clearly circumscribed activity then appears above (up-down) or to the side (side-side) of each eye.