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At least 127 records · Page 7Linked to original sources

PubMed1997

[Functional brain mapping in motor task and somatosensory stimulation using echo planar MRI].

Functional brain mapping was performed with a 1.5T clinical MRI apparatus. Single shot gradient echo echo-planar imaging (EPI) sequence was employed. Normal volunteers were studied with the task of grasping hand or opposition of fingers at the frequency of 3 Hz, median nerve electro-stimulation, pure somatosensory stimulation by roller for acupuncture. Apparent signal increase was observed at contralateral sensorimotor cortex with motor task. Signal changes delayed about 5 seconds compared with the start and the cessation of the task, which may suggest that regional changes of CBF and blood oxygen level in capillary and/or in venule lag behind electrical excitation. It was hard to detect the activated area with median nerve electro-stimulation. On the other hand, roller stimulation provoked distinct activated areas at contralateral sensorimotor cortex. The activated areas caused by the roller stimulation and the motor task coincided entirely, which suggests the possibility of the intermixed localization of primary areas of motor and somatosensory. It was also clearly demonstrated that the activated area was broader with quick (3 Hz) and complicated motor task (finger opposition) than with slow (1Hz) and simple motor task (hand grasping).

Adult↗

PubMed2005

Paramagnetic artifact and safety criteria for human brain mapping.

Biological effects of magnetic field and their safety criteria, especially effects of gradient magnetic field on the cerebral and pulmonary circulation during functional brain mapping are still unclear. Here we estimated that magnetically induced artifacts for the blood oxygenation level- and flow- based functional magnetic resonance imaging are less than 0.1%, and disturbance in the pulmonary circulation is less than 1.3% even if the field strength of magnetic resonance system is risen up to 10 tesla. These paramagnetic effects are considered to be small and harmless during human brain mapping.

Editorial↗

PubMed1997

[Theory and clinical application of functional MRI: 3D-functional brain mapping].

Functional magnetic resonance imaging (fMRI) was performed using a clinical 1.5 T MR scanner. Normal volunteers and patients with several neurological disorders were studied with somatosensory stimulation using sponge at right hand and visual stimulation using checkerboard pattern. Both fMR images by gradient echo echo planar imaging and three dimensional gradient echo images were studied. Reconstructed 3 dimensional functional brain mapping was superimposed on 3D anatomical images. Apparent signal increase was observed at contra lateral sensorimotor cortex and secondary sensory cortex with sponge stimulation. In the case of left homonymous hemianopia due to cerebral infarction, increasing signal was only observed surrounding left calcarine fissure by using stimulation of all visual field. In conclusion, fMRI and 3-D functional brain mapping has extremely high potentiality to examine pathophysiology of various neurological disorders.

Brain↗

PubMed1999

Quantitative imaging of substance P in the human brain using a brain mapping analyzer.

The distribution of substance P (SP)-like immunoreactive neurons in the brains of aged normal human was analyzed quantitatively. Consecutive coronal sections in which the striatum and the substantia nigra were exposed widely, were obtained from the right hemisphere and stained immunohistochemically for SP. Each stained section was divided into approximately three million microareas and the immunohistochemical fluorescence intensity in each area was measured using a human brain mapping analyzer, which is a microphotometry system for analysis of the distribution of neurochemicals in a large tissue slice. These distributions are displayed in color and monochromatic graphics. In the analyzed brain regions, conspicuously intense SP-like immunoreactivity was observed in the substantia nigra and the internal segment of the globus pallidus. Within the substantia nigra, the SP-like immunoreactive intensity in the pars compacta was 25%, higher than that in the pars reticulata, and the distribution of melanin-containing neurons corresponded well to the distribution of the SP-containing structures. SP-like immunoreactive intensity in the internal segment of the globus pallidus, which was lower than that in the substantia nigra, was approximately twice as high as that in the external segment of the globus pallidus. Very intense immunoreactivity was localized at the most medial area of the internal segment of the globus pallidus. The SP-like immunoreactive intensity in the caudate nucleus and putamen was moderate, and the distribution was heterogeneous and observed in patches.

Aged↗

PubMed2005

In vivo auditory brain mapping in mice with Mn-enhanced MRI.

There are currently no noninvasive imaging methods available for auditory brain mapping in mice, despite the increasing use of genetically engineered mice to study auditory brain development and hearing loss. We developed a manganese-enhanced MRI (MEMRI) method to map regions of accumulated sound-evoked activity in awake, normally behaving mice. To demonstrate its utility for high-resolution (100-microm) brain mapping, we used MEMRI to show the tonotopic organization of the mouse inferior colliculus. To test its efficacy in an experimental setting, we acquired data from mice experiencing unilateral conductive hearing loss at different ages. Larger and persistent changes in auditory brainstem activity resulted when hearing loss occurred before the onset of hearing, showing that early hearing loss biases the response toward the functional ear. Thus, MEMRI provides a sensitive and effective method for mapping the mouse auditory brainstem and has great potential for a range of functional neuroimaging studies in normal and mutant mice.

Acoustic Stimulation↗

PubMed1997

Assessment of digital EEG, quantitative EEG, and EEG brain mapping: report of the American Academy of Neurology and the American Clinical Neurophysiology Society [RETIRED].

A. Digital EEG is an established substitute for recording, reviewing, and storing a paper EEG record. It is a clear technical advance over previous paper methods. It is highly recommended. (Class III evidence, Type C recommendation). B. EEG brain mapping and other advanced QEEG techniques should be used only by physicians highly skilled in clinical EEG, and only as an adjunct to and in conjunction with traditional EEG interpretation. These tests may be clinically useful only for patients who have been well selected on the basis of their clinical presentation. C. Certain quantitative EEG techniques are considered established as an addition to digital EEG in: C.1. Epilepsy: For screening for possible epileptic spikes or seizures in long-term EEG monitoring or ambulatory recording to facilitate subsequent expert visual EEG interpretation. (Class I and II evidence, Type A recommendation as a practice guideline). C.2. OR and ICU monitoring: For continuous EEG monitoring by frequency-trending to detect early, acute intracranial complications in the OR or ICU, and for screening for possible epileptic seizures in high-risk ICU patients. (Class II evidence, Type B recommendation as a practice option). D. Certain quantitative EEG techniques are considered possibly useful practice options as an addition to digital EEG in: D.1. Epilepsy: For topographic voltage and dipole analysis in presurgical evaluations. (Class II evidence, Type B recommendation). D.2. Cerebrovascular Disease: Based on Class II and III evidence, QEEG in expert hands may possibly be useful in evaluating certain patients with symptoms of cerebrovascular disease whose neuroimaging and routine EEG studies are not conclusive. (Type B recommendation). D.3. Dementia: Routine EEG has long been an established test used in evaluations of dementia and encephalopathy when the diagnosis remains unresolved after initial clinical evaluation. In occasional clinical evaluations, QEEG frequency analysis may be a useful adjunct to interpretation of the routine EEG when used in expert hands. (Class II and III evidence as a possibly useful test, Type B recommendation). E. On the basis of current clinical literature, opinions of most experts, and proposed rationales for their use, QEEG remains investigational for clinical use in postconcussion syndrome, mild or moderate head injury, learning disability, attention disorders, schizophrenia, depression, alcoholism, and drug abuse. (Class II and III evidence, Type D recommendation). F. On the basis of clinical and scientific evidence, opinions of most experts, and the technical and methodologic shortcomings, QEEG is not recommended for use in civil or criminal judicial proceedings. (Strong Class III evidence, Type E recommendation). G. Because of the very substantial risk of erroneous interpretations, it is unacceptable for any EEG brain mapping or other QEEG techniques to be used clinically by those who are not physicians highly skilled in clinical EEG interpretation. (Strong Class III evidence, Type E recommendation).

Brain↗

PubMed1990

Auditory evoked responses (ABR, MLR, SVR) and brain mapping in the elderly.

The influence of age on evoked auditory brainstem responses (ABRs) is still a matter of controversy. It is well known that in the elderly the ABRs show a progressive latency shift of the principal components. While many authors have reported a I-V internal latency shift, others claim that there is not a delay in the central conduction time (CCT) with ageing. Middle latency auditory evoked responses (MLRs) are also reported to be impaired in the elderly, but the few results published need further investigations. This study investigates some of the controversial aspects of electrophysiological assessment of the auditory system in the elderly. 36 healthy subjects (18 males and 18 females), mean age 67.2 years +/- 5.8, underwent ABRs, MLRs and SVRs and SVRs brain mapping evaluation. All the data were compared with our normative data for young adults. Our results confirm previous reports of a latency shift of all principal components of ABR, but do not demonstrate a significant CCT impairment in the elderly. The MLRs, SVRs and brain mapping analysis also support this conclusion.

Adult↗

PubMed1989

Auditory stimulation brain map.

The topography of auditory evoked potentials (AEPs) was studied in 12 neurologically normal, adult, right-handed subjects of either sex. The AEPs were recorded with seventeen active electrodes in response to 500 Hz tone bursts with a level of 75 dB HL presented either to the left or the right ear. AEP brain maps were obtained with the BRAIN ATLAS III system. A region of maximum negativity was obtained corresponding to N1 at vertex and defined as focus of N1 (FN1). The reproducibility within and between sessions of FN1 was studied and found to be good for most of the subjects. The interindividual variability was moderate and the centre of FN1 on the map was localized 7 mm in front of the vertex electrode and 8.4 and 8.0 mm to the contralateral side of the vertex electrode upon stimulation of the left and the right ear, respectively. The approximate position of the skull surface is obtained by multiplication by a factor of 3. It was concluded that a standardized test session including six single maps based on 50 stimuli each gives an average map with identifiable and reproducible focus. The basis seems to be fulfilled to use the brain map in further analysis on clinical material.

Adult↗

PubMed1992

Topographic brain mapping of emotion-related hemisphere asymmetries.

The study used topographic brain mapping of visual evoked potentials to investigate emotion-related hemisphere asymmetries. The stimulus material consisted of color photographs of human faces, grouped into two emotion-related categories: normal faces (neutral stimuli) and faces deformed by dermatological diseases (emotional stimuli). The pictures were presented tachistoscopically to 20 adult right-handed subjects. Brain activity was recorded by 30 EEG electrodes with linked ears as reference. The waveforms were averaged separately with respect to each of the two stimulus conditions. Statistical analysis by means of significance probability mapping revealed significant differences between stimulus conditions for two periods of time, indicating right hemisphere superiority in emotion-related processing. The results are discussed in terms of a 2-stage-model of emotional processing in the cerebral hemispheres.

Adult↗

PubMed2005

Autism: functional brain mapping of exceptional calendar capacity.

BACKGROUND: 'Autistic savants' are individuals with autism who have extraordinary skills. Brain mechanisms underlying such capacities are still unknown. AIMS: To map the exceptional calendar capacity of a man with primary autism. METHOD: Positron emission tomography was used to map brain activity in a man who is able to associate a day of the week with the corresponding calendar date. RESULTS: During the calendar task, the left hippocampus, the left frontal cortex and the left middle temporal lobe were activated. CONCLUSIONS: The cerebral circuit involved in this man's prodigious calendar skill is similar to that normally involved in memory retrieval tasks. These results suggest that the prodigious capacities may be sustained by memory processing.

Adult↗

PubMed2005

Automated cortical projection of head-surface locations for transcranial functional brain mapping.

Recent advancements in two noninvasive transcranial neuroimaging techniques, near-infrared spectroscopy (NIRS) and transcranial magnetic stimulation (TMS), signify the increasing importance of establishing structural compatibility between transcranial methods and conventional tomographic methods, such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). The transcranial data obtained from the head surface should be projected onto the cortical surface to present the transcranial brain-mapping data on the same platform as tomographic methods. Thus, we developed two transcranial projection algorithms that project given head-surface points onto the cortical surface in structural images, and computer programs based on them. The convex-hull algorithm features geometric handling of the cortical surface, while the balloon-inflation algorithm is faster, and better reflects the local cortical structure. The automatic cortical projection methods proved to be as effective as the manual projection method described in our previous study. These methods achieved perfect correspondence between any given point on the head surface or a related nearby point in space, and its cortical projection point. Moreover, we developed a neighbor-reference method that enables transcranial cortical projection of a given head-surface point in reference to three neighboring points and one additional standard point, even when no structural image of the subject is available. We also calculated an error factor associated with these probabilistic estimations. The current study presents a close topological link between transcranial and tomographic brain-mapping modalities, which could contribute to inter-modal data standardization.

Adult↗

PubMed1999

Integration of preoperative and intraoperative functional brain mapping in a frameless stereotactic environment for lesions near eloquent cortex. Technical note.

The authors present a method of incorporating preoperative noninvasive functional brain mapping data into the frameless stereotactic magnetic resonance (MR) imaging dataset used for image-guided resection of brain lesions located near eloquent cortex. They report the use of functional (f)MR imaging and magnetic source (MS) imaging for preoperative mapping of eloquent cortex in difficult cases of brain tumor resection such as those in which there are large expansive masses or in which reoperations are required and the anatomy is distorted from prior treatments. To correlate methods of preoperative and intraoperative mapping localization directly, the authors have developed techniques of importing preoperative MS and fMR imaging data into an image-guided frameless stereotactic computer workstation. The data appear as a seamless overlay on the same preoperative volumetric MR imaging dataset used for stereotactic guidance during the operation. Intraoperatively identified functional locations mapped by cortical stimulation are recorded as digitally registered points. This approach should prove useful in assessing the accuracy and reliability of various preoperative functional brain mapping techniques.

Adult↗

PubMed1999

Awake craniotomy with brain mapping as the routine surgical approach to treating patients with supratentorial intraaxial tumors: a prospective trial of 200 cases.

OBJECT: Awake craniotomy was performed as the standard surgical approach to supratentorial intraaxial tumors, regardless of the involvement of eloquent cortex, in a prospective trial of 200 patients surgically treated by the same surgeon at a single institution. METHODS: Patient presentations, comorbid conditions, tumor locations, and the histological characteristics of lesions were recorded. Brain mapping was possible in 195 (97.5%) of 200 patients. The total number of patients sustaining complications was 33 for an overall complication rate of 16.5%. There were two deaths in this series, for a mortality rate of 1%. New postoperative neurological deficits were seen in 13% of the patients, but these were permanent in only 4.5% of them. Complication rates were higher in patients who had gliomas or preoperative neurological deficits and in those who had undergone prior radiation therapy or surgery. No patient who entered the operating room neurologically intact sustained a permanent neurological deficit postoperatively. Of the most recent 50 patients treated, three (6%) required a stay in the intensive care unit, and the median total hospital stay was 1 day. CONCLUSIONS: Use of awake craniotomy can result in a considerable reduction in resource utilization without compromising patient care by minimizing intensive care time and total hospital stay. Awake craniotomy is a practical and effective standard surgical approach to supratentorial tumors with a low complication rate, and provides an excellent alternative to craniotomy performed with the patient in the state of general anesthesia because it allows the opportunity for brain mapping and avoids general anesthesia.

Adolescent↗

PubMed1990

EEG-brain mapping in schizophrenics with predominantly positive and negative symptoms. Comparative studies with remoxipride/haloperidol.

EEG brain maps obtained in 48 drug-free hospitalized schizophrenics diagnosed according to DSMIII demonstrated significant differences as compared with normal controls characterized by a decrease of alpha-1 activity, increase of beta activity and acceleration of the centroid. These findings suggest a state of sustained hyperarousal in schizophrenia. While the patients with negative schizophrenia showed a bi-temporal and frontal augmentation of delta/theta activity, patients with florid symptomatology exhibited just the opposite findings. Alpha-1 activity was attenuated, beta activity augmented in both groups with the findings more pronounced in the positive schizophrenia group. The increase of slow activity suggests an organic factor in the pathogenesis of the negative syndrome, which was supported by correlation maps between EEG measures and the apathy syndrome as measured by the AMDP system. Treatment of schizophrenics with predominantly positive symptoms with 2 different neuroleptics such as remoxipride and haloperidol resulted also in differential effects on brain activity: while haloperidol augmented delta/theta and alpha activity and decreased beta activity, remoxipride produced a decrease of slow and increase of beta activity as well as an acceleration of the centroid suggesting vigilance-promoting properties of the drug. These differential effects on the neurophysiological level were also reflected at the behavioural one evaluated by psychometry, while global clinical evaluation showed, as expected, similar improvement with both drugs (apart from extrapyramidal side effects being significantly more pronounced after haloperidol than remoxipride). Our findings suggest that brain electrical signal topography is a promising method in regard to a better understanding of pathogenesis and treatment in schizophrenia.

Adult↗

PubMed1987

[Brain mapping--topographic demonstration of the EEG and evoked potentials in psychiatry and neurology].

Brain mapping of EEG and evoked potentials permits the topographic display of electrical activity of the brain and is superior to conventional polygraphic procedures. Data from 16 scalp electrodes and two ear reference electrodes were worked up. The spontaneous EEG and the EEG during different testing conditions to activate particular brain regions was measured. 2 s EEG data segments were subjected to spectral analysis by a fast Fourier transformation (FFT). For late evoked potentials (VEP, AEP, SEP and P300) a single value representing the amplitude of EP at each 2-ms poststimulus latency point served for subsequent topographic mapping. Statistical techniques (Student's t-test) have been used in conjunction with EEG and EP data to render visible the regions where a clinical population differ from normal subjects. The results show abnormalities of EEG and EP in patients with psychical und neurological diseases.

Arousal↗

PubMed2004

Preoperative mapping for patients with supplementary motor area epilepsy: multimodality brain mapping.

Surgical management and strategies for the supplementary motor area (SMA) epilepsy are described. The following is our preoperative evaluations. The steps include functional magnetic resonance imaging (fMRI), interictal dipole tracing (DT), subdural electrodes mapping, measurements of movement-related cortical potential (MRCP), and the use of the intraoperative open MRI under conscious craniotomy. Six patients with SMA epilepsy underwent surgery after the mapping procedures and are now seizure-free. Combinations of preoperative (fMRI, subdural electrodes mapping) and intraoperative mapping allow exact localization and identification of the critical functional areas. Early postoperative deficits in motor and speech function were profound but patients recovered rapidly. It is concluded that the step of mapping procedures plays an important role in the management of SMA epilepsy surgery.

Adolescent↗

PubMedDate not supplied

Propentofylline in adult-onset cognitive disorders: double-blind, placebo-controlled, clinical, psychometric and brain mapping studies.

In a double-blind, placebo-controlled parallel group trial, the therapeutic efficacy and central effects of propentofylline (HWA 285) - a xanthine derivative with neuroprotective, metabolic, hemorheologic and antithrombotic action - were studied in 190 elderly outpatients with mild to moderate chronic cognitive disturbances (mild dementia, DSM-III-R). They received after a 2-week run-in period (placebo) for 12 weeks either 3 x 300 mg propentofylline or 3 x 1 tablet placebo (given at least 1 h before meals). The verum group (n = 96, age 68 +/- 9) was comparable to the placebo group (n = 94, age 69 +/- 8) in regard to age, height, smoking, consumption of stimulating alcoholic drinks, family and living status. Clinical evaluation by the Gottfries-Brane-Steen (GBS) scale demonstrated a significant superiority of propentofylline over placebo in the total score and the four GBS factors (motor, intellectual, emotional functions and other symptoms) as well as in the clinical global impression and Mini-Mental State. Psychometric measures showed slight and significant improvement in both groups but no intergroup differences. EEG brain mapping was carried out before and after 12 weeks' treatment in the Viennese subsample involving 24 propentofylline and 24 placebo patients. Propentofylline-treated patients exhibited, as compared with placebo-treated ones, a trend towards augmentation of total power, furthermore an increase in relative delta and beta and a decrease in alpha power, an acceleration of the dominant frequency as well as a slowing of the centroid of the combined delta/theta band. The total centroid tended towards acceleration, while the centroid deviation increased significantly. These alterations reflect vigilance changes of the dissociative type and differ from those of the classical nootropics. Clinical and psychometric evaluations demonstrated changes in the same direction as in the total sample, but interdrug differences were not significant. Thus, EEG brain mapping seems to be more sensitive in objectivating central drug effects.

Aged↗

PubMed1995

[Hemispheric functional specialization in motor aphasia. Neurophysiologic findings with computerized electroencephalographic brain mapping during musical and oral sound stimulation. Study of 2 cases].

This study concerns about brain electrical activity during auditory stimulation in 2 aphasic patients, one with classical (left hemisphere lesion) and another with cross aphasia (right hemisphere lesion). Both cases were submitted to dichotic listening test (consonant-vowel-consonant task) and music audition (gregorian chant), during brain mapping examination. We found, in both cases, a great proportion in delta frequency and power in non-lesional hemisphere during dichotic and musical stimulation. Besides, increasing in frequency of alpha activity was observed only in the non-lesional hemisphere restricted to temporal lobe region. Such findings suggest an interesting field of research about measurements of neurophysiological correlates of auditory stimulation and brain electrical activity in aphasia.

Acoustic Stimulation↗