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Results for “Brain Mapping”

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At least 721 records · Page 40Linked to original sources

PubMed2005

Partially distributed representations of objects and faces in ventral temporal cortex.

Object and face representations in ventral temporal (VT) cortex were investigated by combining object confusability data from a computational model of object classification with neural response confusability data from a functional neuroimaging experiment. A pattern-based classification algorithm learned to categorize individual brain maps according to the object category being viewed by the subject. An identical algorithm learned to classify an image-based, view-dependent representation of the stimuli. High correlations were found between the confusability of object categories and the confusability of brain activity maps. This occurred even with the inclusion of multiple views of objects, and when the object classification model was tested with high spatial frequency "line drawings" of the stimuli. Consistent with a distributed representation of objects in VT cortex, the data indicate that object categories with shared image-based attributes have shared neural structure.

Algorithms↗

PubMed2000

Early DAT is distinguished from aging by high-dimensional mapping of the hippocampus. Dementia of the Alzheimer type.

OBJECTIVE: To determine the feasibility of using high-dimensional brain mapping (HDBM) to assess the structure of the hippocampus in older human subjects, and to compare measurements of hippocampal volume and shape in subjects with early dementia of the Alzheimer type (DAT) and in healthy elderly and younger control subjects. BACKGROUND: HDBM represents the typical structures of the brain via the construction of templates and addresses their variability by probabilistic transformations applied to the templates. Local application of the transformations throughout the brain (i.e., high dimensionality) makes HDBM especially valuable for defining subtle deformities in brain structures such as the hippocampus. METHODS: MR scans were obtained in 18 subjects with very mild DAT, 18 healthy elderly subjects, and 15 healthy younger subjects. HDBM was used to obtain estimates of left and right hippocampal volume and eigenvectors that represented the principal dimensions of hippocampal shape differences among the subject groups. RESULTS: Hippocampal volume loss and shape deformities observed in subjects with DAT distinguished them from both elderly and younger control subjects. The pattern of hippocampal deformities in subjects with DAT was largely symmetric and suggested damage to the CA1 hippocampal subfield. Hippocampal shape changes were also observed in healthy elderly subjects, which distinguished them from healthy younger subjects. These shape changes occurred in a pattern distinct from the pattern seen in DAT and were not associated with substantial volume loss. CONCLUSIONS: Assessments of hippocampal volume and shape derived from HDBM may be useful in distinguishing early DAT from healthy aging.

Aged↗

PubMed1998

Topographical and temporal specificity of human intraoperative optical intrinsic signals.

The goal of this study was to determine the topographical and temporal specificity of neuronal and vascular responses using an intraoperative optical technique (iOIS). The face, thumb, index, and middle fingers were stimulated individually to obtain separate maps of cortical activation. Peak optical responses provided unique, non-overlapping cortical brain maps. Non-peak signals were more dispersed and produced overlapping responses from different digits. Peak iOIS responses colocalized with electrocortical stimulation mapping and evoked potentials. Temporally, we observed statistically significant specificity corresponding to sequential cortical activation during early optical signals (500-1750 ms), but later perfusion responses were non-specific. To our knowledge, this is the first report of either topographical specificity in overlapping spatial patterns, and/or temporal specificity in early perfusion profiles. These results therefore may have significant implications for other perfusion dependent functional imaging techniques.

Anesthesia, General↗

PubMed1993

Prenatal growth of the human cerebral cortex: brainprint analysis.

To construct a series of flat maps (brainprints) that document the prenatal growth of human cerebral cortex and help identify sulcal landmarks for division of cortical regions of interest (ROIs) on mapped surfaces, the authors photographed and traced histologic whole-brain slices of 25 normal human fetal brains aged 18-42 weeks gestation. Brainprints of both cerebral hemispheres from each fetus were constructed with semiautomatic brain-mapping software, and each map was divided into five ROIs based on sulcal landmarks: frontal, parietal, insular, occipital, and temporal cortices. Surface areas of cerebral hemispheres and the five ROIs were estimated. Corrected for histologic shrinkage, brainprint estimates of human fetal cortical surface area were approximately twice those of previous estimates. Cortical lobe proportions at 18 weeks appeared to be unchanged to term. Surface area estimates correlated with fetal age, brain weight, and brain volume. This collection of cortical maps may guide future quantitative analyses of cerebral hemispheric growth in premature and term infants who undergo magnetic resonance imaging, which may, in turn, help predict neurobehavioral outcomes of early cortical damage.

Brain Mapping↗

PubMed1993

The utility of topographic EEG mapping in obstructive sleep apnea syndrome.

A study was undertaken to determine whether topographic brain mapping of standard EEG and cognitive evoked potentials would provide additional information for the detection of subtle brain abnormalities associated with obstructive sleep apnea. During nocturnal sleep, significant brain activity was detected in frontal regions not usually monitored with standard sleep recordings. Moreover, preliminary results suggest that total brain activity decreased in association with apneic events and depth of O2 desaturation. Also, component asymmetry in the P300 waveform observed in brain areas not typically recorded improved with treatment. We conclude that the use of topographic mapping adds important information to the study of brain function during sleep and sleep apnea.

Brain↗

PubMed2001

Glasgow Coma Scale, brain electric activity mapping and Glasgow Outcome Scale after hyperbaric oxygen treatment of severe brain injury.

OBJECTIVE: To study the effect of hyperbaric oxy gen (HBO) treatment of severe brain injury. METHODS: Fifty-five patients were divided into a treatment group (n=35 receiving HBO therapy) and a control group (n=20 receiving dehydrating, cortical steroid and antibiotic therapy) to observe the alteration of clinic GCS (Glasgow Coma Scale), brain electric activity mapping (BEAM), prognosis and GOS (Glasgow Outcome Scale) before a nd after hyperbaric oxygen treatment. RESULTS: In the treatment group GCS, BEAM and GOS were improved obviously after 3 courses of treatment, GCS increased from 5.1 to 14.6 (P<0.01-0.001),the BEAM abnormal rate reduced from 94.3% to 38% (P<0.01-0.001), the GOS good-mild disability rate was 83.7%, and the middle-severe disability rate was 26.3% compared with the control group. There was a statistic significant difference between the two groups (P<0.01-0.001). CONCLUSIONS: Hyperbaric oxygen treatment could improve obviously GCS, BEAM and GOS of severe brain injury patients, and effectively reduce the mortality and morbidity. It is an effective method to treat severe brain injury.

Adult↗

PubMed2003

The significance of increase in striatal D(2) receptors in epileptic EL mice.

The present study systematically and quantitatively analyzed the immunohistochemical distribution of various substances involved in synthesis, binding, and transport of dopamine in the forebrain of epileptic mice (EL mouse strain) using a brain mapping analyzer. A reduction in serum calcium levels decreases calcium/calmodulin-dependent-dopamine synthesis in the brain and subsequently increases susceptibility to epileptic convulsions and induces abnormal behavior in EL mice. The immunohistochemical levels of D(2) receptors in the medial area of the neostriatum were significantly higher in EL mice than in ddY mice (mother strain of EL mice), while there were no differences in the levels of tyrosine hydroxylase, calcium/calmodulin-dependent protein kinase II, calmodulin, D(1) receptors, and dopamine transporters. Together with our previous findings, the results suggest that the decrease in serum calcium levels and subsequent decrease in brain dopamine synthesis comprise the primary physiologic disorder in EL mice, and convulsions or increased D(2) receptors are secondarily-induced phenomena to improve or compensate for the principal disorder.

Animals↗

PubMed1997

[The data processing of neurophysiological examination and the diagnostic support system].

Neurophysiological examinations include EEG, EMG, Evoked Potential (EP) and ENG. In this paper, EEG and EP data processing, and the diagnostic support system using these findings were discussed. The FFT and AR model for analysis of frequency, and the pattern recognition for spike or spindle detection are the technical methods for application to EEG data processing of the first order. Amplitude or phase mapping techniques, as a second order data processing, were not only applied to the diagnosis of neurological disorders, but also used for detection of electrical equivalent dipole source localization which was inversely reconstructed in the cerebral cortex from the distribution of EEG potentials on the scalp. The averaging technique was used for detection of small evoked potentials (EP) such as SEP or ABR. The following items were included in the diagnostic support system applied to data processing. 1) Topographic analysis in the brain mapping of SEP to median nerve stimulation was applied to the identification of the central sulcus during a neurosurgical procedure to maintain the QOL of patient. 2) The usefulness of EEG automatic reporting system with Japanese sentences and brain topographic mapping was described. 3) Digital EEG in a data filing system using magneto optical disks was used for data analysis and diagnostic support system after EEG examination.

Algorithms↗

PubMed2004

Registration and real-time visualization of transcranial magnetic stimulation with 3-D MR images.

This paper describes a method for registering and visualizing in real-time the results of transcranial magnetic stimulations (TMS) in physical space on the corresponding anatomical locations in MR images of the brain. The method proceeds in three main steps. First, the patient scalp is digitized in physical space with a magnetic-field digitizer, following a specific digitization pattern. Second, a registration process minimizes the mean square distance between those points and a segmented scalp surface extracted from the magnetic resonance image. Following this registration, the physician can follow the change in coil position in real-time through the visualization interface and adjust the coil position to the desired anatomical location. Third, amplitude of motor evoked potentials can be projected onto the segmented brain in order to create functional brain maps. The registration has subpixel accuracy in a study with simulated data, while we obtain a point to surface root-mean-square error of 1.17+/-0.38 mm in a 24 subject study.

Adolescent↗

PubMed1991

Resection of intrinsic tumors from nondominant face motor cortex using stimulation mapping: report of two cases.

We report two right-handed patients who underwent resection of intrinsic glial tumors from the nondominant hemisphere, face motor cortex. Both patients underwent preoperative assessment with computed tomography and magnetic resonance imaging localizing the tumor in the inferior region of the Rolandic cortex. With the patients under general anesthesia and without muscular paralysis, the tumor volume was determined by intraoperative ultrasound and resective surgery accomplished with the aid of cortical and subcortical stimulation mapping techniques. Radical resection of the tumor from the face motor cortex was achieved in both patients. A transient contralateral facial weakness and apraxia were noted in each patient, and this resolved within 6 to 8 weeks following surgery. Removal of intrinsic tumors involving the nondominant face motor cortex may be safely achieved using brain mapping techniques to localize inferior Rolandic cortex and avoid resection of the hand motor cortex and descending subcortical motor pathways. Permanent disability will be prevented due to the bilateral representation of face motor function at the neocortical level. However, due to language localization in cortical zones contiguous with the dominant hemisphere, face motor cortex, we do not recommend resection of this region.

Adolescent↗

PubMed1991

Plasticity of auditory maps in the brain.

The central auditory pathway contains maps of sound frequency that reflect the functional organization of the cochlea, as well as topographic representations of other stimulus features, such as sound location, that are synthesized within the brain. Both types of map undergo changes during development and are shaped by experience. This is particularly true of the representation of auditory space in the superior colliculus, which can be modified by alteration of auditory and visual inputs early in life. Although experience-induced plasticity in this map is restricted primarily to the developmental period, the frequency representation in the cortex of adult animals can re-organize following partial deafness.

Acoustic Stimulation↗

PubMed2003

Practice and difficulty evoke anatomically and pharmacologically dissociable brain activation dynamics.

Brain activation is adaptive to task difficulty and practice. We used functional MRI to map brain systems activated by an object-location learning task in 24 healthy elderly volunteers each scanned following placebo and two of four active drugs studied. We distinguished a fronto-striatal system adaptive to difficulty from a posterior system adaptive to practice. Fronto-striatal response to increased cognitive load was significantly attenuated by scopolamine, sulpiride and methylphenidate; practice effects were not modulated by these drugs but were enhanced by diazepam. We also found enhancement by methylphenidate, and attenuation by sulpiride, of load response in premotor, cingulate and parietal regions comprising a spatial attention network. Difficulty and practice evoke anatomically and pharmacologically dissociable brain activation dynamics, which are probably mediated by different neurotransmitter systems in humans.

Adrenergic Uptake Inhibitors↗

PubMedDate not supplied

[Inter- and intrahemispheric disorders in certain types of mental pathology].

Asymmetry of EEG rhythms and intercortical interaction in patients with Major Depression and schizophrenia with negative and positive symptoms were studied by the method of brain mapping. It was shown that in depressive patients the disturbance between anterior and posterior brain areas takes place; in schizophrenics with negative symptoms left hemisphere and in schizophrenics with positive symptoms--right hemisphere are predominantly activated. These inter- and intrahemispheric disturbances correlate with some clinical manifestations of the patients.

Adolescent↗

PubMed1995

c-fos immunoreactivity in the brain following electrical or chemical stimulation of the medial hypothalamus of freely moving rats.

c-fos immunoreactivity was used to map brain areas in which neurons reacted either to electrical stimulation or to microinjection of the excitatory amino acid kainate and of the GABAA antagonist, SR-95531, applied to the medial hypothalamus of freely moving rats. All these stimulations induced flight behavior of moderate intensity. Immunoreactive cells were found within a radius of 0.5 mm around the stimulated area. Distally, clusters of labeled cells were found ipsilaterally in the piriform and entorhinal cortices, in several amygdaloid nuclei, in the bed nucleus of the stria terminalis, in the septo-hypothalamic nucleus, in the paraventricular, anterior and dorsomedial hypothalamic nuclei, the the paraventricular thalamic nucleus, in the dorsal periaqueductal gray extending to the cuneiform nucleus, and bilaterally in the supramammillary decussation and the locus coeruleus. The specificity of the brain areas thus labeled was indicated by the unilateral pattern of activation as well as by the different pattern obtained after control microinjection of saline. Therefore, these results are likely to provide sound information about the brain structures involved in defensive-aversive behavior evoked from the medial hypothalamus.

Animals↗

PubMed2003

Source distribution of neuromagnetic slow-wave activity in schizophrenic patients--effects of activation.

When slow waves in the EEG delta and theta frequency range appear in the waking state, they may indicate pathological conditions including psychopathology. The generators of focal slow waves can be mapped using magnetic source imaging. The resulting brain maps may possibly characterize dysfunctional brain areas. The present study examined the stability of the density and distribution of MEG slow waves during three conditions-rest, mental arithmetic and imagery-in 30 schizophrenic patients and 17 healthy controls. Schizophrenic patients displayed a higher density of delta and theta generators primarily in temporal and parietal areas. The group difference was not affected by the particular conditions. The focal concentration of delta and theta slow waves did not differ between patients with and without neuroleptic medication, whereas the prominence of theta dipoles in the temporal area correlated with neuroleptic dosage. The relative amount of temporal slow waves was correlated with the negative symptoms score (PANSS-N) suggesting that temporal dysfunction may be related to negative symptomatology.Results suggest that the distribution of slow-wave activity, measured in a standardized setting, might add diagnostic information about brain abnormalities in schizophrenia.

Adult↗

PubMed2006

Stimulation mapping via implanted grid electrodes prior to surgery for gliomas in highly eloquent cortex.

OBJECTIVE: To evaluate whether preoperative mapping of higher cortical functions with subdural grid electrodes can help to maximize resection in functional areas and avoid permanent injury. METHODS: A consecutive series of 16 patients (female: n = 7, male: n = 9, mean age of 38 yr) with a history of seizures and without focal deficit was reviewed, harboring gliomas located in the dominant hemisphere adjacent to or in the F3 gyrus/Broca area (n = 11), parietal/perisylvian area (n = 5) and additionally the pre- or postcentral area (n = 15). All patients in this series were operated for cytoreductive purposes only and not for treatment of intractable seizures. To preoperatively define and intraoperatively tailor the extent of resection all patients had a presurgical grid implantation for functional brain mapping. RESULTS: No permanent morbidity/mortality was observed after grid implantation and resective surgery. On postoperative MRI the resection was complete (100%), nearly complete (>90%) in n = 9 and subtotal (60% to <90%) in n = 5 cases. Twice, only biopsies were taken according to the results of mapping. All patients with high-grade gliomas had adjuvant treatment with radiation and chemotherapy. After a mean follow up of 20.4 months, no tumor relapse or growth was seen in all cases of resection. CONCLUSION: Preoperative grid mapping is a safe and precise instrument to evaluate language and/or associated left perisylvian functions in patients with gliomas. It may be considered a valid alternative to awake craniotomy to maximize safe resection.

Adolescent↗

PubMed2004

Structural abnormalities in the brains of human subjects who use methamphetamine.

We visualize, for the first time, the profile of structural deficits in the human brain associated with chronic methamphetamine (MA) abuse. Studies of human subjects who have used MA chronically have revealed deficits in dopaminergic and serotonergic systems and cerebral metabolic abnormalities. Using magnetic resonance imaging (MRI) and new computational brain-mapping techniques, we determined the pattern of structural brain alterations associated with chronic MA abuse in human subjects and related these deficits to cognitive impairment. We used high-resolution MRI and surface-based computational image analyses to map regional abnormalities in the cortex, hippocampus, white matter, and ventricles in 22 human subjects who used MA and 21 age-matched, healthy controls. Cortical maps revealed severe gray-matter deficits in the cingulate, limbic, and paralimbic cortices of MA abusers (averaging 11.3% below control; p < 0.05). On average, MA abusers had 7.8% smaller hippocampal volumes than control subjects (p < 0.01; left, p = 0.01; right, p < 0.05) and significant white-matter hypertrophy (7.0%; p < 0.01). Hippocampal deficits were mapped and correlated with memory performance on a word-recall test (p < 0.05). MRI-based maps suggest that chronic methamphetamine abuse causes a selective pattern of cerebral deterioration that contributes to impaired memory performance. MA may selectively damage the medial temporal lobe and, consistent with metabolic studies, the cingulate-limbic cortex, inducing neuroadaptation, neuropil reduction, or cell death. Prominent white-matter hypertrophy may result from altered myelination and adaptive glial changes, including gliosis secondary to neuronal damage. These brain substrates may help account for the symptoms of MA abuse, providing therapeutic targets for drug-induced brain injury.

Adult↗

PubMed2001

Differential expression of Fos protein in the rat brain induced by performance of avoidance or escape in the elevated T-maze.

Analysis of Fos protein expression was used to map brain areas activated by exposure of male Wistar rats to the elevated T-maze, an animal model of anxiety where tasks of inhibitory avoidance or one-way escape can be separately performed. The apparatus consists of three elevated arms--one enclosed and two open. In the inhibitory avoidance task--considered to represent learned fear--the time taken by rats to leave from the enclosed arm in three consecutive trials is measured. One-way escape task is measured by recording the time taken by animals to withdraw from the open arm and is thought to reflect innate fear. Control animals were placed three times at the end of the transversal arm of a T-maze composed of three enclosed arms and withdrawal latencies from this arm was similarly measured. Performance of avoidance task increased Fos-like immunoreactivity in the medial amygdaloid nucleus, in the anterior hypothalamic nucleus and in the median raphe nucleus. In contrast, performance of escape task enhanced Fos-like immunoreactivity in the basolateral amygdaloid nucleus and in the dorsal periaqueductal gray matter of the mesencephalon. Both behavioural tasks promoted an increase in Fos-like immunoreactivity in the paraventricular nucleus of the thalamus and in the dorsomedial hypothalamic nucleus. Therefore, the obtained results indicate that different sets of brain structures were, respectively, activated by inhibitory avoidance and one-way escape. This evidence supports the original hypothesis that two types of fear/anxiety are generated in the elevated T-maze.

Animals↗