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At least 19 recordsLinked to original sources
PubMedDate not supplied

Functional brain studies with H2(15)O-PET: strategies and problems for approaching higher brain functions with H2(15)O-PET.

Activation study using H2(15)O and PET is promising as a noninvasive approach to higher brain functions in humans. However before reaching a more complex paradigm, many fundamental problems need to be solved. In this study, we investigated the following issues: (1) reproducibility of regional cerebral blood flow in the resting state as measured by this method, (2) effect of physiological stimulation on cerebral blood flow, and (3) identification of activated areas on anatomical structures. Our data suggest that relative CBF images and their paired subtraction are more suitable for tapping functional localization. Changes in rCBF in the association cortex for more complicated tasks are, in general, smaller than those in the primary cortex. Combined display of PET images with three-dimensional reconstructed brain surface MR images was the most reliable technique for anatomical identification of the activated site.

Acoustic Stimulation↗
PubMed1985

Functional brain imaging.

Recent advances in brain imaging have allowed a regional examination of brain function using multiple-probe inert gas studies of cerebral blood flow, positron or single photon tomography. Inert gas blood flow methods using inhalation or injection of 133xenon have been used with multiple-probe systems to measure blood flow in 1 to 2 cm regions of lateral cortex. The sensitivity of these systems to neurophysiological stimuli and neurological diseases have been demonstrated in numerous studies of the normal resting state, memory and learning, motor activity and sensory input, dementia, and aphasia, to name some. Positron tomography utilizes cyclotron-produced, short-lived positron-emitting isotopes to label biologically active radiopharmaceuticals. Using positron tomographs capable of quantitative three-dimensional imaging and appropriate tracer-kinetic models, regional metabolic function, including glucose, oxygen, amino acid metabolism, and receptor-binding can be regionally studied throughout the brain. Clinical studies have been performed in dementia, schizophrenia, affective disorders, resting states, and sensory stimulation. Positron tomography offers potentially the greatest variety of studies and highest temporal and spatial resolution of any of the presently available functional brain-imaging modalities. Its principal drawback is the very high cost. Single photon tomography uses gamma-emitting isotopes such as 123iodine and 133xenon to image regional cerebral blood flow and recently receptor function. Although at present it does not have the variety of studies or the technical capabilities of positron tomography, it does provide three-dimensional studies with 1 to 2 cm resolutions throughout the brain at a considerably lower cost than positron tomography. In the future, magnetic resonance studies of blood flow or phosphorus metabolism may add a fourth modality.

Brain↗
PubMed1991

Functional brain asymmetry and lymphocyte proliferation in female mice: effects of right and left cortical ablation.

Brain immunomodulation may be lateralized as evidenced by two experimental approaches. Using a behavioral paradigm, we have reported an association between asymmetrical brain function and lymphocyte reactivity in mice selected for right- and left-paw preference. Left-handed mice, in comparison to right-handers, exhibit higher mitogen-induced T-lymphocyte proliferation. Using a cortical lesion paradigm in mice, it has been previously shown that each hemicortex modulates in opposite directions lymphocyte reactivity. In these experiments, the role of the brain cortex in the association between paw preference and immune reactivity was assessed by studying mitogen-induced lymphoproliferation in left- and right-handed mice after right or left-cortical ablation. The difference in T-lymphocyte responsiveness between right- and left-handed mice persisted after right lesions but was abolished after left lesions. This immunological effect of left cortical ablation is hypothesized to involve the hypothalamic dopaminergic neurons.

Analysis of Variance↗
PubMed1989

Diagnosis and assessment of dementia using functional brain imaging.

Functional brain imaging using computer-analyzed electroencephalography was performed in 40 subjects: 15 with mild-to-moderate dementia of the Alzheimer's type (DAT), 13 with mild-to-moderate multi-infarct dementia (MID), and 12 age-matched controls. We examined three different parameters of brain electrical activity in these subjects: absolute slow-wave power, proportional power in all frequency bands, and ratios of high-frequency/low-frequency electrical activity (so-called "spectral ratios"). Spectral ratios were significantly more powerful in discriminating among groups than the other measures. Functional images using spectral ratios revealed that subjects with DAT have a characteristic left temporo-parietal defect which clearly distinguished them from subjects with MID and from control subjects. The severity of dementia was best assessed by examining absolute slow-wave power, which had the strongest linear correlation with mental status testing. Serial images from one subject with DAT over 3 years demonstrate both quantitative and qualitative shifts in slow-wave activity in the course of DAT. The study suggests that functional imaging may be more useful than either simple EEG or computer-analyzed EEG in assessing and diagnosing patients with suspected dementia.

Aged↗
PubMed2026

Effects of permissive hypercapnia on intraoperative cerebral oxygenation and early postoperative cognitive function in older patients with fragile brain function during the non-acute phase undergoing laparoscopic colorectal surgery: A randomized controlled trial.

BACKGROUND AND PURPOSE: Older adults with non-acute fragile brain function (NFBF) may be particularly susceptible to perioperative disturbances in cerebral oxygenation and postoperative neurocognitive decline. Permissive hypercapnia (PHC) may enhance cerebral oxygenation, but its effects in this population remain unclear. We examined whether PHC-based ventilation improves intraoperative regional cerebral oxygen saturation (rSO2) and early postoperative cognitive outcomes in older patients with NFBF undergoing elective laparoscopic colorectal surgery. METHODS: In this single-center, single-blind randomized trial, 76 patients were assigned in a 1:1 ratio to PHC-based or conventional ventilation. The primary outcome was the absolute change in rSO2 from baseline (T0) to the end of surgery (T4). Analyses followed the intention-to-treat principle, with prespecified per-protocol sensitivity analysis. Secondary outcomes included intraoperative rSO2 trajectories, cerebral oxygen extraction-related indices, early postoperative cognitive screening, serum neuron-specific enolase and interleukin-6, and safety outcomes. RESULTS: PHC significantly increased rSO2 relative to conventional ventilation (left: adjusted mean difference [aMD] 10.64, 95% CI 8.96-12.33; right: aMD 10.16, 95% CI 8.22-12.11; both P&#xa0;<&#xa0;0.001), with consistent sensitivity results. Repeated-measures analyses showed persistently higher intraoperative rSO2 in the PHC group. Cerebral oxygen extraction-related indices were generally lower with PHC. However, early postoperative cognitive outcomes and serum biomarkers did not differ between groups. Emergence time was modestly longer with PHC, whereas adverse events were comparable. CONCLUSIONS: PHC-based ventilation favorably modified intraoperative cerebral oxygenation and oxygen-extraction profiles but did not translate into detectable early postoperative cognitive or biomarker benefits in older adults with NFBF.

Humans↗
PubMed2026

Shared genetic architecture between major depression and intrinsic brain functional connectome organization.

BACKGROUND: Major depression (MD) is increasingly understood as a disorder characterized by widespread abnormalities in intrinsic brain functional network organization. Although both MD and brain functional connectome architecture are highly heritable, the genetic architecture underlying their relationship remains poorly characterized. METHODS: We integrated genome-wide association studies of MD with 191 ICA-based resting-state functional connectome traits to investigate their shared genetic architecture. These traits captured intrinsic connectome organization across amplitude, functional connectivity, and global connectivity domains. Cross-trait genetic analyses were used to assess pleiotropic overlap between traits. Locus-level and gene-based analyses integrating multi-omics evidence were performed to characterize the biological relevance of shared genetic signals. RESULTS: We identified significant genetic overlap between MD and 148 of 191 brain functional connectome traits. Cross-trait analyses revealed widespread shared genetic signals organized into 627 genomic loci across amplitude, functional connectivity, and global connectivity measures. Among these, 193 loci showed evidence consistent with shared causal variants based on colocalization analyses. Gene-level integration mapped these loci to 1459 protein-coding genes (390 unique genes). Multi-layer prioritization identified 17 high-confidence genes supported by convergent genomic, transcriptomic, and proteomic evidence, with enrichment in neurodevelopmental and lipid-related metabolism pathways. CONCLUSIONS: This study provides a multi-scale characterization of the shared genetic architecture between MD and intrinsic brain functional connectome organization, revealing that shared genetic signals between MD and brain functional systems are distributed across multiple functional levels and converge at the molecular level.

Connectome↗
PubMed1975

An auditory illusion predicted by a theory of brain function.

A theory of brain function has resulted in the hypothesis that dichotic auditory stimuli of differing intensities would be subjectvely heard to occur at different times if presented together. The louder of the two tones would always be heard first. The results of an experiment designed to test the hypothesis have established that the predicted illusory judgment will invariably be made. The further prediction that the magnitude of the effect would closely parallel certain reaction time data was substantiated. It seems reasonable to conclude that the same paradigm must underlie both sets of data. The theory and obtained results provide a possible neurophysiological basis for the perception of rhythm. A review of the literature has shown that results analogous to those reported here have previously been reported for the visual and tactile modalities, as would be predicted from the general considerations of the theory which gave rise to the specific hypotheses tested in this experiment.

Acoustic Stimulation↗
PubMed1992

An automated method for rotational correction and centering of three-dimensional functional brain images.

The display and analysis of functional brain images often benefit from head rotational correction and centering. An automated method was developed to align brain PET images into a standard three-dimensional orientation. The algorithm performs transverse and coronal rotational correction as well as centering of a brain image set. Optimal rotational correction and centering are determined by maximizing a bilateral hemispheric similarity index, the stochastic sign change criterion. Testing of this algorithm on simulated symmetrical brain image sets showed errors less than 1.0 degree and 0.5 pixels for rotational correction and centering, respectively. With actual PET data, the algorithm results correlated well with those obtained by visual inspection. Testing on asymmetrical brain image sets with simulated lesions indicated that performance of the algorithm is not sensitive to focal asymmetries. This automated method provides objective, reproducible image alignment into a standard orientation and facilitates subsequent data analysis techniques for functional brain images.

Algorithms↗
PubMed2025

Glaucoma and brain functional networks: a bidirectional Mendelian randomisation study.

OBJECTIVE: Glaucoma is a complex neurodegenerative ocular disorder accompanied by brain functional abnormalities that extend beyond the visual system. However, the causal association between the two remains unclear at present. This study aimed to investigate the potential causal relationships between glaucoma and brain functional networks in order to provide novel insights into the neuropathic mechanism of glaucoma. METHODS AND ANALYSIS: Based on the genome-wide association studies data of glaucoma and resting-state functional MRI (Rs-fMRI), a bidirectional Mendelian randomisation (MR) analysis was conducted between glaucoma and brain functional networks. Inverse variance weighting was applied as the primary method to estimate causality with false discovery rate correction. Additional sensitivity analyses were conducted to evaluate the robustness of the results. RESULTS: Forward MR analysis suggested that glaucoma was causally associated with two brain networks between the subcortical cerebellum and the attention or visual network (p=0.022), as well as the default mode and central executive network (p=0.008), but without significance after false discovery rate correction (q>0.1). Reverse MR analysis revealed 19 Rs-fMRI traits related to glaucoma risk, including the salience or central executive network in the frontal region (p=0.0005, q=0.08) and the motor network (p=0.0009, q=0.08) with significant causality. CONCLUSIONS: This MR study revealed potentially causal relationships between glaucoma and brain functional networks. Especially, the functional connectivity of the motor network between the postcentral or precentral areas may potentially lead to increased risk of glaucoma.

Humans↗
PubMed1989

Search for nutritional confounding factors in the relationship between iron deficiency and brain function.

This paper on confounding factors in the relationship between iron deficiency and brain function is mainly limited to nutritional factors, primarily factors that can contribute to the development of iron deficiency and that may have an independent direct action on brain function. Three theoretically possible confounders were found in a systematic search for dietary factors: 1) low intake of ascorbic acid, 2) excess of phytates, and 3) increased absorption of lead. Ascorbic acid has a marked effect on the bioavailability of dietary iron and is also known to directly influence various metabolic processes in the brain. Phytates inhibit the absorption not only of iron but also of zinc. An iron deficiency may thus be accompanied by a zinc deficiency which may affect mental performance. A state of iron deficiency may increase the absorption of lead from the diet, which in turn may affect brain function.

Animals↗
PubMedDate not supplied

Magnetic resonance imaging of brain function.

New techniques for imaging of brain function are described, which utilize magnetic resonance imaging. Echo-planar imaging (EPI), the preferred method, is introduced and technical issues are discussed. Two recent approaches for measurement of blood flow are explained: contrast agent bolus tracking and black blood perfusion. An intrinsic contrast technique, which utilizes the paramagnetism of deoxyhemoglobin, is presented. Results from experiments on functional imaging of the human brain are shown, and the specific advantages of MRI for this purpose are discussed.

Animals↗
PubMed1989

Postnatal treatment of rats with beta-adrenergic agonists or antagonists influences differentiation of sexual brain functions.

Sexual differentiation of the brain seems to be influenced by postnatal interaction of gonadal steroids with neurotransmitter systems, in particular the adrenergic system. Stimulation or inhibition of alpha-adrenergic receptors during early postnatal development had previously been shown to influence steroid-induced sexual differentiation of brain functions. In the present study newborn male and female rats were treated either with salbutamol, a selective beta 2-adrenergic receptor agonist, isoprenaline, a general beta-adrenergic receptor agonist, or with alprenolol, a general beta-adrenergic receptor antagonist. In adulthood the female animals were ovariectomized and were tested for the capacity to show an LH-surge response and female sexual behaviour after priming with estradiol benzoate (EB) and progesterone (P). Male animals were tested for expression of male sexual behavior and, after gonadectomy and priming with EB + P, for the capacity to show female lordosis behavior. In summary, our results suggest that activation or inhibition of beta-adrenergic receptors during postnatal development permanently impairs the responsiveness of the center for cyclic gonadotropin release to gonadal steroids in female rats and impairs the expression of ejaculatory behavior in male rats. A slight stimulatory effect on the expression of female lordosis behavior was observed in male and female rats after postnatal activation of beta-adrenergic receptors.

Albuterol↗
PubMed1978

Brain function, intellectual impairment and education in the aged.

In assessing behavioral problems of the elderly there is a need for procedures which reliably indicate the presence and extent of impaired brain function. In this study, the relation of two mental status measures [the Mental Status Questionnaire (MSQ) and the Face-Hand test] to intellectual performance and education was evaluated. The sample consisted of 153 consecutive inpatients and outpatients referred to a gerontology clinic. Intellectual performance was assessed with 8 tests of learning and memory, such as Paired Associates and Babcock Story Recall. The findings indicate that positive ratings for impaired brain function on either mental status test were related to lower intellectual performance at each of three levels of education - grade school, high school, and college. Subjects with more education and mental status scores indicating mild impairment performed better on intellectual tests than did less educated persons with no brain dysfunction, but they showed significant deficits compared to other subjects with similar education and intact brain function. Larger intellectual deficits were found when the patient made more test errors and when both tests gave positive ratings. These results confirm the importance of the MSQ and Face-Hand tests as screening devices for the intellectual deficits associated with impaired brain function in a clinically heterogeneous population.

Aged↗
PubMed1978

[A neurometric analysis of brain functions after halothane anaesthesia, neuroleptanalgesia and combined acupuncture-analgesia (author's transl)].

In a comparative examination of the effects on brain function of three anaesthetic methods--halothane anaesthesia, neuroleptanalgesia and combined acupuncture-analgesia--typical and characteristic changes in brain metabolism, brain electrical activity or psychological test parameters were observed with each method. Brain function is understood here as complex of consciousness and pain. Loss of consciousness is defined as the suspension of intelligence quotient with characteristic changes of brain activity and metabolism. Pain is defined as the central perception of senses evoked by peripheral sensors. Loss of consciousness is only the evident and monotone finishing result of different effects of the anaesthetic methods on brain function. In using combined acupuncture analgesia a hypalgetic method is introduced to the anaesthetists armamentarium. Possible mode of action are discussed. In place of the name acupuncture-analgesia ther term electrohypalgesia is recommended.

Acupuncture Therapy↗