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At least 919 records · Page 51Linked to original sources
PubMed2005

Human brain structures related to plantar vibrotactile stimulation: a functional magnetic resonance imaging study.

The purpose of this study was to investigate the sensorimotor cortex response to plantar vibrotactile stimulation using a newly developed MRI compatible vibration device. Ten healthy subjects (20-45 years) were investigated. Vibrotactile stimulation of the sole of the foot with a frequency of 50 Hz and a displacement of 1 mm was performed during fMRI (echo-planar imaging sequence at 1.5 T) using an MRI compatible moving magnet actuator that is able to produce vibration frequencies between 0 and 100 Hz and displacement amplitudes between 0 and 4 mm. The fMRI measurement during vibrotactile stimulation of the right foot revealed brain activation contralaterally within the primary sensorimotor cortex, bilaterally within the secondary somatosensory cortex, bilaterally within the superior temporal, inferior parietal, and posterior insular region, bilaterally within the anterior and posterior cingular gyrus, bilaterally within the thalamus and caudate nucleus, contralaterally within the lentiform nucleus, and bilaterally within the anterior and posterior cerebellar lobe. The advantages of the new MRI compatible vibration device include effective transmission of the stimulus and controlled vibration amplitudes, frequencies, and intensities. The results indicate that plantar vibration can be a suitable paradigm to observe activation within the sensorimotor network in fMRI. Furthermore, the method may be used to determine the optimal responsiveness of the individual sensorimotor network.

Adult↗
PubMedDate not supplied

[Mediator processes in the brain structures in the late periods after external and combined exposure to ionizing radiation].

In experiments with mature Wistar male rats it was shown that X-radiation of 12.9 mCi/kg and the combined effect of X-rays and 131I of 6.5 mCi/kg changed the rate of mediator processes in the structures responsible for the hypothalamic function regulation. At remote times (6 months) following irradiation differences were observed in the discoordination of mediator interrelations associated with the peculiarities of the indirect effect of external and combined irradiation implemented via endocrine mechanism system.

Animals↗
PubMed1993

Cognitive functions and brain structures: a quantitative study of CSF volumes on Alzheimer patients and healthy control subjects.

In the present study we have investigated the connection between cerebrospinal fluid spaces and cognitive function in patients with senile dementia of Alzheimer type (SDAT) and in successfully aged control subjects. The cerebrospinal fluid (CSF) volumes were measured using a low field MRI technique, and the cognitive functions were assessed with a number of psychometric tests. We found that the SDAT patients showed significantly larger relative volumes in all examined CSF spaces. The largest differences between the groups were found in the volumes of the temporal horns. We also found a significant correlation between the relative CSF volumes in the basal parts of the brain, and episodic memory tests. Significant correlations were also detected between the relative volumes of the lateral ventricles, and degree of dementia as well as between the relative volumes of the lateral ventricles and episodic memory tests.

Aged↗
PubMed2005

Effects of traumatic stress on brain structure and function: relevance to early responses to trauma.

The events of 9/11 and the widening impact of psychological trauma today have raised a higher level of awareness about the potentially deleterious effects of psychological trauma on the individual. One area of interest after 9/11 was the early trauma response and the most effective way to deal with the window of time immediately after traumatization in order to prevent long term psychopathology. Understanding the neurobiology of the acute trauma response may be useful in designing prevention and treatment strategies. Studies in animals and humans have shown that biological stress response systems, including norepinephrine and cortisol, are affected in both the acute and chronic stages of the trauma response. Brain areas involved in memory, including the hippocampus, amygdala, and prefrontal cortex, may be areas of intervention to ameliorate the early trauma response. Due to the difficulty of performing research in this time period, most research to date has been in patients with chronic disorders such as chronic posttraumatic stress disorder (PTSD). Only a few treatment studies have been performed in the early trauma period, and more research in this area is needed.

Brain↗
PubMed1987

The influence of long-term treatment with haloperidol on neuronal activity and sensitivity in several brain structures of the rat.

The influence of long-term haloperidol pretreatment on neuronal spontaneous activity and transmitter sensitivity was investigated in prefrontal cortex, hippocampus and locus coeruleus. The changes are different in all areas as well as in the transmission systems involved. In particular cases, analogies exist between haloperidol- and isolation-induced changes, reflecting a comparable dopaminergic supersensitivity.

Action Potentials↗
PubMed1975

Implications of genetic variation in mouse brain structure for electrode placement by stereotaxic surgery.

The spatial locations of several forebrain and midbrain fibre tracts have been compared across seven commonly used inbred, hybrid and outbred mouse strains using a series of electrolytic lesions of known positions with respect to a stereotaxic instrument. Highly significant genetic variation was found in the position of lambda, bregma and several major fibre tracts with respect to interaural zero; in the locations of fibre tracts with respect to bregma; and in the location of fibre tracts with respect to each other. It was demonstrated that stereotaxic coordinates of a structure for one strain could not be used for other strains. Errors resulting from improper alignment of the head in the instrument and histological artifact were also determined. These errors showed no significant group differences, but they revealed that within-group variation was substantially affected by such imperfections.

Animals↗
PubMed2001

Neuroendocrine regulation of sexually dimorphic brain structure and associated sexual behavior in male rats is genetically controlled.

Steroid hormones, particularly 17beta-estradiol (E2), regulate the development and expression of neural structures and sexual behavior. Recently, we demonstrated that E2-regulated responses are controlled by quantitative trait loci. In this study, we quantified 1) volume of the sexually dimorphic nucleus (SDN) of the preoptic area (POA); 2) medial basal hypothalamic (MBH)-POA aromatase and 5alpha-reductase enzyme activities during prenatal development and in adults; 3) serum LH, testosterone, FSH, E2, prolactin (PRL), and corticosterone levels; 4) reproductive organ (i.e., testis and ventral prostate) weights; and 5) male mating behavior in Noble (NB/Cr) and Wistar-Furth (WF/NCr) rat strains to determine the genetic influence on the measured parameters. Maximal phenotypic divergence in male SDN-POA volumes was seen between NB/Cr versus WF/NCr and BDIX/Cr rats (among nine rat strains initially examined), with the average SDN-POA volume of NB/Cr male rats being significantly greater ( approximately 30%) than that of either WF/NCr or BDIX/Cr males. Subsequent experiments investigated WF/NCr versus NB/Cr male rats in further detail. Significantly higher MBH-POA aromatase activity was seen in adult WF/NCr versus NB/Cr males, while MBH-POA 5alpha-reductase rates were not significantly different (within or between sex) for the two rat strains assayed. Serum LH levels were significantly higher (by greater than sixfold) in WF/NCr versus NB/Cr males, whereas testis organ:body weight and ventral prostate:body weight ratios in WF/NCr versus NB/Cr males were significantly smaller (by approximately 6-fold for testis and approximately 1.5-fold for prostate values). Serum FSH levels were significantly higher (by twofold) in WF/NCr versus NB/Cr males. However, serum testosterone levels were not significantly different, whereas E2 levels were approximately twofold higher (but not significantly different) in WF/NCr versus NB/Cr animals. No significant differences were found in basal (i.e., nonstress) serum PRL or corticosterone levels between the WF/NCr and NB/Cr males. In male copulatory tests, NB/Cr males exhibited significantly more aggressive sexual behavior (e.g., in mounting, intromission, and ejaculation parameters) compared with WF/NCr males. Taken together, these findings indicate that WF/NCr males are, in general, low responders, whereas NB/Cr males are high responders to hormonal signals. The obtained data suggest that the correlative, phenotypic variation in SDN-POA volume (i.e., structure) and reproductive hormone patterns and mating behavior (i.e., function) of WF/NCr versus NB/Cr males is regulated by potentially E2-mediated mechanisms that are genetically controlled.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1993

The representation of patterns of structural brain asymmetry in normal individuals.

Hemispheric asymmetries were examined in 20 normal individuals who underwent MR scanning. The asymmetry indices were represented for a series of contiguous, consecutive coronal images through the occipital and frontal lobes, along the dorso-ventral [DV] axis. A monotonic decrease in size of the parieto-occipital hemispheric areal asymmetry was observed, from a marked left predominance to a greater degree of symmetry. When frontal and occipital lobe asymmetries were compared, the familiar frontal-right vs occipital-left counterclockwise torque was observed, but was found to be more prominent in the dorsal aspect of the frontal cuts and the ventral aspect of the occipital cuts. At the individual level, a within-subject linear model for predicting cerebral area as a function of cut, hemisphere and DV, revealed this marked DV effect. The use of the within-subject linear model further enabled the individual assessment of structural asymmetries, and provided criteria by which subjects could be grouped. We further show how a deviation of the occipital falx will engender different hemispheric asymmetries, depending on the orientation of the coronal imaging plane. Given the latter, we recommend planning the coronal cuts based on a low-ventricular transaxial scout, wherein the deviated falx, if present, can be taken into account.

Adolescent↗
PubMed1987

Relative growth of the higher fetal brain structures.

In a retrospective review of 90 normal obstetric ultrasonographic examinations obtained between 15 and 35 menstrual weeks, measurements were made of the transverse dimensions of the thalamus, basal ganglia/insula, atrium of the lateral ventricle, and temporal operculum in the standard biparietal diameter plane. At 15 menstrual weeks the echogenic choroid plexus, filling the lateral ventricle, dominates the appearance of the cranium. During later gestation, the cerebral hemispheres and basal ganglia (telencephalic structures) show marked growth, while the diencephalon and lateral ventricles increase much less rapidly in size. This observation is made using a method of measurement that least favors the demonstration of cerebral cortical growth. Of note is that the width of the lateral ventricle remains relatively stable throughout the second and third trimesters.

Brain↗
PubMed1992

[The Na+,K(+)-ATPase activity in the brain structures of neuroticized rats differing by the threshold of nervous system excitability].

A 2-week neurotization of two rat lines formed a long-term stress and increased neuronal Na+,K(+)-ATPase activity in hippocampus, locus coeruleus and n. raphe dorsalis, whereas the glial enzyme activity was decreased in hippocampus and N. raphe dorsalis. (Line H). In rats with low threshold of excitability (line L), the decrease of the Na+,K(+)-ATPase activity occurred in n. raphe dorsalis and hippocampus. After a 15-day rest, the activity decreased in all the structures of the line rats, whereas in the line L rats the activity was still increased in hippocampal neurons. Differences between the rat lines and dependence of the enzyme activity on the functional state of the nervous system, are discussed.

Animals↗
PubMed1992

Role of different brain structures in the expression of the physical morphine withdrawal syndrome.

The aim of this study was to investigate the neuroanatomical regions implicated in the expression of the physical signs of morphine withdrawal by using local intracerebral injections of methylnaloxonium in dependent rats. Guide cannulas were implanted and aimed at the lateral ventricle, nucleus accumbens, central amygdala, anterior hypothalamus, medial thalamus, periaqueductal gray matter, locus coeruleus and nucleus raphe magnus. After surgery, rats were made physically dependent by s.c. implantation of two 75-mg morphine pellets. Methylnaloxonium, a quaternary derivative of naloxone (31-1000 ng), was administered 72 hr after pellet implantation. Methylnaloxonium administered i.c.v. induced a withdrawal syndrome similar to systemic naloxone, although several signs such as diarrhea, salivation, lacrimation and rhinorrhea did not appear, suggesting possible peripheral mediation. The most sensitive site for methylnaloxonium-precipitated withdrawal was the locus coeruleus. Signs such as jumping, rearing and locomotor activity were particularly frequent after methylnaloxonium injections into the locus coeruleus. Rearing and locomotor activity were also strongly increased after methylnaloxonium administration into the periaqueductal gray matter. Wet dog shakes were mainly observed after methylnaloxonium administration into the anterior preoptic hypothalamus and nucleus raphe magnus. Injections of methylnaloxonium into the amygdala produced a weak withdrawal syndrome, and the nucleus accumbens and medial thalamus were the least sensitive structures. These results suggest that the locus coeruleus, and secondarily the periaqueductal gray matter, play an important role in the precipitation of the physical signs of opiate withdrawal, mainly in the expression of its motor component. The expression of other signs of withdrawal appear to be multisite determined.

Animals↗
PubMed1981

[Electrophysiologic correlates of interaction between desynchronized and synchronized brain structures during sleep and wakefulness].

The relations of the basal preoptic area to mesencephalic RF, center median of the thalamus, hippocampus and posterior hypothalamus were studied in cats with the aid of positive wave (P-wave) evoked by preoptic stimulation during wakefulness and sleep. In light slow wave sleep, the amplitude and duration of P-wave increased for all the structures except hippocampus. Correlation between the P-wave amplitude in hippocampus and the duration of the paradoxical sleep was revealed. In paradoxical sleep, the P-wave of the mesencephalic RF and the center median was reduced as compared to wakefulness. Various functional properties of the P-wave evoked by preoptic stimulation, are discussed.

Animals↗
PubMed1999

Relationship between brain structure sizes and performing rapid limb movements. A quantitative magnetic resonance study.

In this study, we aimed to determine the relationship between the size of cerebral structures evaluated by quantitative magnetic resonance technique and the ability of performing rapid-velocity limb movements. Forty-seven healthy women with a mean age of 43.4 years (range 22-68) were included. Exclusion criteria were systemic diseases including alcoholism. Finger and ankle tapping were quantitatively recorded for both right and left extremities. A mean value for the right and left side was calculated. To determine atrophy, we measured the area of the corpus callosum, the cerebrum and the cerebellum on midline sagittal sections. On transverse images, the ventricle-to-brain ratio, the bifrontal ratio and the bicaudate ratio were selected as atrophy parameters. Also, the prevalence of white matter hyperintensities was assessed. Fifteen (32%) had hyperintense white matter lesions. Using simple regression analysis, the frequencies of both finger (r = 0.37, beta = -0.002, p = 0.022) and ankle (r = 0.35, beta = -0.001, p = 0.032) tapping were associated with reduced cerebellar size. No association was found for other atrophy parameters or the number of hyperintense white matter lesions. This study indicates that impaired ability to perform fast limb movements may be related to a relative cerebellar atrophy.

Adult↗
PubMed1988

[Effect of 2-pyrrolidone and gamma-butyrolactone on the rate of 14C-leucine incorporation into the proteins of different brain structures and of their arterial tissues].

The ability of cyclic GABA and GHBA derivatives--2-pyrrolidone and gamma-butyrolactone--to increase markedly the inclusion of 14C-leucine in the proteins of hypothalamus and cerebral arteries both normally and in condition of cerebral blood supply disturbances produced by unilateral 20 min ligation of a common carotid artery has been demonstrated.

4-Butyrolactone↗
PubMedDate not supplied

[Changes in the oxygen tension level in different brain structures of rats in the waking-sleep cycle].

Changes of oxygen tension level (pO2) in the visual cortex, dorsal hippocampus, lateral hypothalamus and central grey substance were studied during wake-sleep cycle in rats. The dependence was established of pO2 level changes on the character of behavioural reactions and on the accompanying hippocampal EEG activity: during orienting-investigatory and active defensive behaviour and also during paradoxical sleep, accompanied by hippocampal theta rhythm, pO2 level increased; during passive-defensive behaviour "freezing" reaction accompanied by desynchronization of the hippocampal rhythmic, the level of pO2 decreased. The obtained data confirm Routtenberg hypothesis about two relatively independent systems of ascending activation with different types of hippocampal EEG activity and supplement it with a thesis that the activity of these systems is accompanied by different shifts of brain oxidative metabolism.

Animals↗
PubMed1990

Changes in 5-HT1 receptors in different brain structures of rats with isolation syndrome.

1. Prolonged (3 month) individual housing of Wistar rats produced aggressive muricidal behavior in 28% of the animals. 2. Binding studies with [3H]5-HT showed that the affinity (Kd) of 5-HT1 receptors in the frontal cortex, striatum, hippocampus and hypothalamus of isolated aggressive rats was significantly decreased as compared to that in grouped rats. 3. The affinity of 5-HT1 receptors was also significantly decreased in the striatum, hippocampus and hypothalamus of isolated nonaggressive rats. 4. The number (Bmax) of 5-HT1 receptors was significantly decreased in the hippocampus and hypothalamus of isolated aggressive rats and in isolated nonaggressive rats it was decreased only in the hypothalamus. 5. The data suggest that aggressive muricidal behavior in rats with syndrome of social isolation is connected with the decreased activity of brain 5-HT1 receptors.

Aggression↗