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At least 613 records · Page 34Linked to original sources
PubMed2000

Functional mapping of human brain in olfactory processing: a PET study.

This study describes the functional anatomy of olfactory and visual naming and matching in humans, using positron emission tomography (PET). One baseline control task without olfactory or visual stimulation, one control task with simple olfactory and visual stimulation without cognition, one set of olfactory and visual naming tasks, and one set of olfactory and visual matching tasks were administered to eight normal volunteers. In the olfactory naming task (ON), odors from familiar items, associated with some verbal label, were to be named. Hence, it required long-term olfactory memory retrieval for stimulus recognition. The olfactory matching task (OM) involved differentiating a recently encoded unfamiliar odor from a sequentially presented group of unfamiliar odors. This required short-term olfactory memory retrieval for stimulus differentiation. The simple olfactory and visual stimulation resulted in activation of the left orbitofrontal region, the right piriform cortex, and the bilateral occipital cortex. During olfactory naming, activation was detected in the left cuneus, the right anterior cingulate gyrus, the left insula, and the cerebellum bilaterally. It appears that the effort to identify the origin of an odor involved semantic analysis and some degree of mental imagery. During olfactory matching, activation was observed in the left cuneus and the cerebellum bilaterally. This identified the brain areas activated during differentiation of one unlabeled odor from the others. In cross-task analysis, the region found to be specific for olfactory naming was the left cuneus. Our results show definite recruitment of the visual cortex in ON and OM tasks, most likely related to imagery component of these tasks. The cerebellar role in cognitive tasks has been recognized, but this is the first PET study that suggests that the human cerebellum may have a role in cognitive olfactory processing as well.

Adolescent↗
PubMed2000

Topographic mapping of the brain activity of perceived motion.

The study compared electrical brain activity of 6 subjects in 5 different conditions. Absolute theta and alpha power in the frontal, parietal, and occipital areas were analyzed, with significant differences found only in the frontal area. Results suggested that the perception of movement requires higher order cognitive processing outside the occipital area. Implications for education and cognitive research are discussed.

Adult↗
PubMed1976

Computer mapping of brain-stem sensory centers in man.

A computer program is described for use on-line with a two--stage stereotaxic technique in man. It has four capabilities. It transposes coordinates between a brain atlas and a stereotaxic frame, simultaneously adjusting for variations in individual brain dimensions. Corrections for electrode trajectories, and for any irregularities of placement of the stereotaxic frame in the head are also made. It plots an operative template that shows electrode trajectories and the sites from which physiological data are collected appropriately oriented upon a sagittal diagram of the brain. It graphically displays physiological data in the form of a Woolsey-type figurine chart that indicates threshold in milliamperes and, through the use of coded symbols, the quality of response and certain other data. It stores all this data in a tape library together with the locations of any lesions made. This makes it possible to replot any individual patient's operative data at any time. It also permits scanning of the stored protocols from all patients for any particular type of data either by itself or in combination with other data. This retrieved information is plotted on appropriate sagittal brain diagrams corrected for individual variations in brain size. Illustrations of the capabilities of the program are presented particularly with reference to the primary afferent pathways of the upper brain stem.

Afferent Pathways↗
PubMed2000

Trance surgery in Brazil.

This report presents the results of fieldwork in Brazil on healer-mediums who perform crude forms of surgery, often employing sharp instruments. We found that these healer-mediums were in a hyperaroused brain state while they were engaged in behaviors commonly described in the anthropology literature as "possession trance"; therefore, this practice is termed "trance surgery" in this report. The research was conducted at widely scattered sites throughout Brazil. We observed several thousand patients being treated by 9 trance surgeons and videotaped several hundred of these cases. In addition to background information and our own observational material, this paper includes 2 medical case reports, physiological data gathered from healers and patients, and results of a pathologist's examination of a surgically excised tumor. Topographic brain mapping revealed increased brain activity (36-44 Hz) when healer-mediums were engaged in trance behaviors, compared to resting baseline conditions at midline scalp locations (Cz, P < .009 and Pz, P < .004; both matched t tests). These results suggest the presence of a hyperaroused brain state associated with the trance behaviors of the healers. We believe that such a state is required for this unusual practice, but other factors may also be involved. In contrast, a small sample of patients monitored during possession trance surgical procedures revealed no high-frequency brain activity; instead, there were indications of cortical quieting, suggesting relaxation, despite the absence of anesthesia. Pathohistological examination of a tumor excised from a patient in our presence revealed a human fibroadenoma. We conclude that these practices are usually benign and that pain is often absent, despite the lack of sterile procedures and anesthesia. Although during the period of our investigation we were informed anecdotally of 3 cases involving serious complications or death, we personally observed no cases of shock, hemorrhage, or death. The cases presented in this paper, as well as others we have followed, suggest that serious illnesses, not likely to improve without treatment, may do so after trance surgery procedures are performed. If the major benefit of trance surgery is to initiate self-healing processes, it would have to do so in powerful ways, which possibly can be elucidated with positron emission tomography and functional magnetic resonance imaging scans. Positive findings would be helpful in understanding large-scale healing effects and may lead to new treatment protocols.

Aged↗
PubMed1994

[EEG spike focus topography: study of potential fields].

Mapping study of EEG spike focus was performed on 122 topographic maps, from 88 records of 72 subjects, classified in: F for "functional" (no epileptic seizure); EGI, EGS and EGC: respectively generalized idiopathic, symptomatic and cryptogenic epilepsies; EPI, EPS and EPC: respectively partial idiopathic, symptomatic and cryptogenic epilepsies--epilepsies with centro-temporal spikes (EPR) are predominant in this group--; EI: indeterminate epilepsies. The graphoelements study: morphology, localization, amplitude, time course (sites of appearance, culmination and disappearance) and of electrical fields: distribution, monopolar, bipolar or intermediary aspect was performed. In order to quantify the brain mapping data we established series of numeric parameters: maximal negative and positive values; sum of the negative and positive values; ratio of these values. EGS and EPS groups have very variable map imaging for a patient or from a patient to another, r1 ratio is lower to 0.33. Idiopathic epilepsies are characterised by the stability of imaging, in the EGI group aspect is frequently monopolar with a central negativity, r1 and r2 ratios are high (0.9 and 1.2); in the EPI group the aspect can be monopolar or bipolar, in the EPR the aspect is stable, longitudinal bipolar, r1 and r2 ratios are between 0.33 and 0.99. In the EGC, EPC and EI groups there is no typical imaging, the mapping aspect can be monopolar or bipolar, in EGC and EPC r1 ratio is between 0 and 0.99, in EI r1 and r2 ratios are low (r1 = r2 = 0.2). In the F group the monopolar aspect is frequent. We can note the stability of the electrical fields apportionment in idiopathic epilepsies which is explainable by the integrity of the cerebral potential propagation pathways in spite of a dysfunction responsible of the epileptic seizures, the presence of a lesion is one of the responsible factors of the instability of the brain mapping.

Adolescent↗
PubMed1986

Substance P neuronal cell bodies in the human brain: complete mapping by immunohistofluorescence.

The localization of substance P-immunoreactive (SP-IR) cells was studied in 5 postmortem brains from aged human subjects using technical improvements combined with the indirect immunofluorescence method. The presence of various forms of SP-IR cells was observed in paleocortical and neocortical areas as well as in the basal ganglia, the brainstem and the spinal cord. The distribution of these SP-IR cell bodies was transposed onto our previous mapping of SP-IR fibers and terminals. The morphological differences between SP-containing cell bodies or areas of human and rat central nervous systems and the SP-changes in various states of human pathology are shortly discussed.

Aged↗
PubMedDate not supplied

EEG in migraine: a review of the literature.

EEG abnormalities in migraine have been reported by a number of authors during the last 50 years. Prevalences vary considerably in the older literature. A number of unspecific rhythms related to drowsiness or hyperventilation have probably been counted as "abnormal", and the reported numbers of definitely abnormal EEG rhythms have been consistently low. In a few controlled and blinded studies, however, slight excess of various EEG rhythms has been found in migraine patients. Similar prevalences of interictal EEG abnormalities have generally been found in patients with classic and common migraine, but the diagnostic classification may not have been precise enough in some studies. During visual aura, either slow waves, depression of background activity amplitude or normal EEG have been reported. The most definitely abnormal EEGs with unilateral or bilateral delta activity have been recorded during attacks of hemiplegic migraine, and during attacks of migraine with disturbed consciousness. The relationship between migraine and epilepsy has still not been adequately clarified. The connection seems to exist in several small entities (e.g. migraine-like headache as an epileptic manifestation, epileptic seizures triggered by epileptic attacks, and possibly in epilepsies with occipital spike waves), but it is seemingly not "fundamental". Newer methods, i.e. EEG frequency analysis and topographic brain mapping, are promising tools in this field. So far, mostly small studies have been published with somewhat inconsistent results. A pattern of increased alpha rhythm variability (and/or asymmetry) in the headache-free phase seems to emerge, however. Significant asymmetry of alpha and theta during headache has been reported in one topographic brain mapping study. Magnetoencephalographic studies of migraine patients have demonstrated slow wave-shifts (similar to those observed in animals with spreading depression). The EEG patterns observed in migraine patients seem to suggest a possible physiological connection between sleep, hyperventilation and migraine. The study of such relationship may shed new light on migraine pathophysiology.

Brain Mapping↗
PubMed2003

Isotropic apparent diffusion coefficient mapping of postnatal cerebral development.

Diffusion-weighted imaging (DWI) allows us to image the motion of tissue water. This has been used to demonstrate acute ischaemia. Diffusion imaging is also sensitive to water movement along neuronal tracts. Our objective was to map brain maturation in vivo using maps of apparent diffusion coefficient (ADC). We studied 22 children without neurological disease aged between 2 and 720 days. MRI was performed at 1.5 tesla. Multislice single-shot echoplanar DWI was performed at b 0 and 1000 s/mm(2). ADC maps were generated automatically and measurements were performed in the basal ganglia, frontal and temporal white matter and the pons. There was a decrease over time in water diffusion in the areas examined, most marked in the frontal (0.887-1.898 x 10(-3) mm(2)/s) and temporal (1.077-1.748 x 10(-3) mm(2)/s)lobes. There was little change, after an initial decrease, in the basal ganglia (0.690-1.336 x 10(-3) mm(2)/s). There was a difference in water diffusion between the anterior (0.687-1.581 x 10(-3) mm(2)/s) and posterior (0.533-1.393 x 10(-3) mm(2)/s) pons. These changes correlate well with those observed in progressive myelination: the increased water content probably reflects incomplete myelination and the decrease with time in water motion reflects the increase in myelinated brain.

Brain Mapping↗