Lateral brain function, emotion, and conceptualization.
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Brain↗
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Results for “brain function”
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[Brain function vs. mental activity].
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Animals↗
[Physiological roles of cyclic nucleotide dependent protein kinases in advanced brain functions].
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Animals↗
[Geriatric and pathologic aspects of deteriorating brain function].
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Aged↗
Of lasers, mutants, and see-through brains: functional neuroanatomy in zebrafish.
Behavioral functions are carried out by localized circuits in the brain. Although this modular principle is clearly established, the boundaries of modules, and sometimes even their existence, are still debated. Zebrafish might offer distinct advantages in localizing behaviors to discrete brain regions because of the ability to visualize, record from, and lesion precisely identified populations of neurons in the brain. In addition, genetic screens in zebrafish enable the isolation of mutations that disrupt neural pathways and/or behaviors, as an alternative lesioning technique with complementary strengths to laser ablations. For example, the Mauthner cell, a large identified neuron in the hindbrain, has been postulated to be both necessary and sufficient for the execution of escapes. We discuss in this review how experiments, using laser ablations, calcium imaging, and mutants have eroded this notion. Even in a simple behavior, such as escape, many parallel pathways appear to be involved with no single one being absolutely necessary. Lesion studies and the analysis of behavioral mutants are now also beginning to elucidate the functional architecture of the zebrafish visual system. Although still in an embryonic stage, the neuroanatomy of behaviors in zebrafish has a bright future.
Animals↗
Radiotracers for functional brain imaging.
The rapid growth of nuclear medicine 25 years ago was in large part related to the success of brain tumor imaging using radiopharmaceuticals designed to detect changes in the blood-brain barrier (BBB). The success of computed tomography, and more recently nuclear magnetic resonance, in imaging these lesions has all but eliminated the use of radioactive agents for brain tumor detection. But, in recent years there has been a new wave of interest in isotope studies of the brain. The recent emphasis has been on agents which enter the brain across the BBB and are designed to provide functional data ranging from regional perfusion and metabolism to the distribution of binding sites for neuroactive compounds. While none of these new radiopharmaceuticals has yet come into widespread clinical application, the research results already achieved clearly indicate that brain imaging will again be an important aspect of nuclear medicine practice.
Amphetamines↗
A 4D approach to the analysis of functional brain images: application to FMRI data.
This paper presents a new approach to functional magnetic resonance imaging (FMRI) data analysis. The main difference lies in the view of what comprises an observation. Here we treat the data from one scanning session (comprising t volumes, say) as one observation. This is contrary to the conventional way of looking at the data where each session is treated as t different observations. Thus instead of viewing the v voxels comprising the 3D volume of the brain as the variables, we suggest the usage of the vt hypervoxels comprising the 4D volume of the brain-over-session as the variables. A linear model is fitted to the 4D volumes originating from different sessions. Parameter estimation and hypothesis testing in this model can be performed with standard techniques. The hypothesis testing generates 4D statistical images (SIs) to which any relevant test statistic can be applied. In this paper we describe two test statistics, one voxel based and one cluster based, that can be used to test a range of hypotheses. There are several benefits in treating the data from each session as one observation, two of which are: (i) the temporal characteristics of the signal can be investigated without an explicit model for the blood oxygenation level dependent (BOLD) contrast response function, and (ii) the observations (sessions) can be assumed to be independent and hence inference on the 4D SI can be made by nonparametric or Monte Carlo methods. The suggested 4D approach is applied to FMRI data and is shown to accurately detect the expected signal.
Brain Chemistry↗
Insights into brain function and neural plasticity using magnetic source imaging.
This review outlines the rationale for the use of magnetoencephalography (MEG) or magnetic source imaging (MSI), a noninvasive functional imaging technique, and the features that any imaging method should display to make a substantial contribution to cognitive neuroscience. After a brief discussion of the basic experimental approach used in the authors' studies, the use of early sensory components of brain magnetic responses is reviewed to address issues of the functional organization of the primary sensory cortices, followed by a comment on the clinical use of these components. Second, normative studies focusing on the late components of magnetic responses for establishing the validity and reliability of MSI maps of the language-specific cortex in normal subjects are reviewed. Third, the authors' investigations of fine spatiotemporal features of brain activation maps, specific to receptive language and to reading, are reviewed. Fourth, experience with presurgical mapping of the language-specific cortex in neurosurgery candidates and in patients undergoing the "Wada" procedure is summarized followed by a comment on the perfect agreement of the MSI maps with those derived by more direct invasive brain mapping procedures. Fifth. MSI-derived evidence of often dramatic, functional reorganization of brain areas subserving both simple sensory and linguistic functions is summarized along with comments on the use of MSI as a means for investigating brain plasticity. Finally, in the sixth section of this review, the authors relate their experience with the use of MSI in deriving brain activation profiles during silent reading of real words and pseudowords that are specific to dyslexic children. The review concludes with a discussion on the further use of MSI in assessing, among other issues, the effectiveness of intervention strategies designed to improve reading fluency in dyslexic children.
Acoustic Stimulation↗
Affective vs thinking disturbance related to left- vs right-sided brain functioning.
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Adolescent↗
A new method for brain functional study using Tc-99m HMPAO SPECT.
The distribution of 99mTc-HMPAO in brain is in proportion to regional cerebral blood flow (rCBF) and can be interpreted as functional mapping. To evaluate local changes in CBF during neuropsychological testing, we developed a new subtraction method using HMPAO and SPECT. With patients resting, 15 mCi of HMPAO was injected and the first acquisition was performed, lasting a total of 10 minutes. Soon after the end of the first scan, patients were requested to undergo Buschke's memory test or to repeat words or numbers (repetition test). During the task, an additional 15 mCi of HMPAO was injected using the same position as in the first scan, and a second acquisition was started. A functional image was made by subtracting the image in the first scan from that in the second. In two patients with transient global amnesia and two normal controls, Buschke's memory test was performed in combination with SPECT. A Relative increase in activity was seen in the thalamus, subthalamic area, hippocampus, and some cortical areas, apparently reflecting local functional change induced by the memory task. In two patients with moderate Alzheimer's disease with severe memory loss, no increase was detected in these areas. In one patient with aphasia, the repetition test with SPECT was correlated with the WADA test and dichotic listening test, and good agreement was obtained. In conclusion, our new SPECT technique is useful in detecting alterations in rCBF during mental activity and can be applied to neurophysiological studies.
Alzheimer Disease↗
[Audiometric and dynamometric parameters of functional brain asymmetry].
We examined influence of intensive noise on auditory and musculoskeletal system in series of audiometric and dynamometric tests. We considered Karhart's tooth asymmetry and asymmetry of muscular strength of the upper extremities. We demonstrate the significance of these parameters in diagnosis of functional cortical asymmetry and central hearing pathology; provide audiometric and dynamometric evidence of the structure of cortical auditory pathways, the integral function of the auditory cortex, pathophysiological nature of functional asymmetry and their correlation.
Audiometry↗
Brain function early after stroke in relation to subsequent recovery.
This study aimed to characterize brain activation and perfusion early after stroke within cortical regions that would later change activation during recovery. Patients were studied serially after stroke (mean t1, = 16 days after stroke, t2 = 3.5 months later) using perfusion-weighted imaging and functional magnetic resonance imaging during finger movement. Controls (n = 7) showed no significant change in regional activation volumes over time. Among stroke patients (n = 8), however, recovery was accompanied by several patterns of functional magnetic resonance imaging change, with increased activation volumes over time in five patients and decreased in two. Most regions increasing activation over time were in the stroke hemisphere. Of the five patients showing increased activation over time, specific activation foci enlarged at t2 were already activated at t1 in four patients, and at least one focus growing from t1 to t2 was in a different arterial distribution from the infarct in all five patients. Perfusion of sensorimotor cortex at t1 was generally not reduced in the stroke hemisphere (94% of noninfarcted hemisphere). Improved clinical outcome was related to increased activation within sensory cortices of both brain sides, including bilateral secondary somatosensory areas. Early after stroke, cortical activation that will later increase in parallel with recovery is often already identifiable, can be remote from the vascular territory of the infarct, and is not likely hindered by reduced perfusion. The findings may be useful for restorative interventions introduced during the weeks after a stroke.
Adult↗
[Science of learning and education: an approach with brain-function imaging].
From a biological viewpoint, learning and education are closely related to brain development because the brain is an adaptable information processor open to the environment. Stimuli from the environment cause new neuronal connections. Therefore, learning is the process in which the brain reacts to stimuli by making neuronal connections that act as an information processing circuit and provide information storage similar to a database. On the other hand, education is a process that should guide and inspire the construction of the basic architecture of brain information processing by preparing and controlling the input stimuli to the brain.
Brain↗
Structural and functional brain development and its relation to cognitive development.
Despite significant gains in the fields of pediatric neuroimaging and developmental neurobiology, surprisingly little is known about the developing human brain or the neural bases of cognitive development. This paper addresses MRI studies of structural and functional changes in the developing human brain and their relation to changes in cognitive processes over the first few decades of human life. Based on post-mortem and pediatric neuroimaging studies published to date, the prefrontal cortex appears to be one of the last brain regions to mature. Given the prolonged physiological development and organization of the prefrontal cortex during childhood, tasks believed to involve this region are ideal for investigating the neural bases of cognitive development. A number of normative pediatric fMRI studies examining prefrontal cortical activity in children during memory and attention tasks are reported. These studies, while largely limited to the domain of prefrontal functioning and its development, lend support for continued development of attention and memory both behaviorally and physiologically throughout childhood and adolescence. Specifically, the magnitude of activity observed in these studies was greater and more diffuse in children relative to adults. These findings are consistent with the view that increasing cognitive capacity during childhood may coincide with a gradual loss rather than formation of new synapses and presumably a strengthening of remaining synaptic connections. It is clear that innovative methods like fMRI together with MRI-based morphometry and nonhuman primate studies will transform our current understanding of human brain development and its relation to behavioral development.
Adolescent↗
Altered PET functional brain responses in cognitively intact elderly persons at risk for Alzheimer disease (carriers of the epsilon4 allele).
OBJECTIVE: Few previous studies have investigated the association between APOE genotype and brain activation during performance of cognitive tasks in healthy middle-aged and elderly subjects, and the results have been mixed. The authors investigated APOE-mediated differential brain activation in a group of healthy elderly subjects. METHODS: Using H215O positron emission tomography (PET), they imaged 32 healthy subjects (26 non-epsilon4 carriers and 6 epsilon4 carriers) performing a serial shape-recognition memory task under two conditions: Simple Demand (SD), in which one shape was presented in each study trial, and Titrated Demand (TD), in which study list length was adjusted so that each subject recognized words at approximately 75% accuracy. Multiple-regression analyses were performed, with the "activation" difference (TD-SD PET counts) as the dependent variable and the APOE genotype (presence versus absence of the epsilon4 allele) as the independent variable. RESULTS: Compared with non-carriers, epsilon4 carriers exhibited significantly decreased TD-SD activation differences in the left superior temporal, right superior frontal, left postcental, left precuneus, and posterior cingulate gyrus because epsilon4 carriers (versus non-carriers) showed increased activation during the SD and decreased activation during the TD condition. CONCLUSION: Patterns of brain activation during a nonverbal memory task differed as a function of APOE genotype and, therefore, of genetic risk for Alzheimer disease (AD). Differences in activation were not a reflection of task difficulty, but indicate memory-related altered cognitive processing. Brain regions with decreased activation in the epsilon4 subjects may result from subclinical incipient AD pathology and/or APOE-related neurophysiologic heterogeneity.
Aged↗
Magnetic resonance imaging and magnetic resonance spectroscopy assessment of brain function in experimental animals and man.
This paper introduces the basic principles and techniques of functional magnetic resonance imaging (fMRI) and spectroscopy (MRS). Examples are given of single event human fMRI studies on control subjects, and a graded activation protocol applied to Parkinsonian patients. Possibilities are discussed for using fMRI techniques to study the neural substrate of various pharmacological agents, including drugs of abuse. The application of these pharmacological MRI (phMRI) studies to animal models and the associated technical issues are also addressed. The use of MRS in studying brain status and function is reviewed, with particular emphasis on 13C isotopic labelling studies.
Animals↗
Cord damage elicits brain functional reorganization after a single episode of myelitis.
OBJECTIVE: To assess, using fMRI, the brain pattern of movement-associated cortical activations in patients with a previous remitting episode of acute cervical myelitis of possible demyelinating origin and to investigate whether the extent of cortical reorganization is associated with the extent of cervical cord pathology measured using magnetization transfer (MT) MRI. METHODS: From 14 right-handed patients in a chronic and stable phase after an isolated myelitis (male/female = 7/7, mean age = 35.3 years, median disease duration = 21.2 months) involving the cervical cord and 15 sex- and age-matched healthy control subjects, we obtained 1) fMRI during repetitive flexion-extension of the last four fingers of the right hand, 2) brain diffusion tensor MRI, and 3) brain and cervical cord conventional and MT MRI. FMRI data were analyzed using Statistical Parametric Mapping software. Brain mean diffusivity, fractional anisotropy, and MT ratio (MTR) histograms of the normal-appearing white and gray matter and cervical cord MTR histograms were produced. RESULTS: Patients with myelitis had lower average cord MTR (p < 0.0001) and cord MTR histogram peak position (p = 0.002) than control subjects. Compared with healthy volunteers, patients with myelitis showed increased recruitment of the ipsilateral hemisphere in the primary sensorimotor cortex (p < 0.0001), supplementary motor area (p = 0.002), and middle frontal gyrus (MFG) (p < 0.0001). Average cervical cord MTR was inversely correlated with relative activations of the ipsilateral MFG (r = -0.80) and of the ipsilateral postcentral gyrus (r = -0.80). The relative activation of the ipsilateral MFG was also correlated with cervical cord MTR peak position (r = -0.92). CONCLUSIONS: An abnormal pattern of movement-associated cortical activations was found in patients with a previous episode of cervical myelitis. These functional cortical changes might have an adaptive role in limiting the clinical outcome of structural cord damage.
Acute Disease↗
Functional brain mapping during free viewing of natural scenes.
Previous imaging studies have used mostly perceptually abstracted, idealized, or static stimuli to show segregation of function in the cerebral cortex. We wanted to learn whether functional segregation is maintained during more natural, complex, and dynamic conditions when many features have to be processed simultaneously, and identify regions whose activity correlates with the perception of specific features. To achieve this, we used functional magnetic resonance imaging (fMRI) to measure brain activity when human observers viewed freely dynamic natural scenes (a James Bond movie). The intensity with which they perceived different features (color, faces, language, and human bodies) was assessed psychometrically in separate sessions. In all subjects different features were perceived with a high degree of independence over time. We found that the perception of each feature correlated with activity in separate, specialized areas whose activity also varied independently. We conclude that even in natural conditions, when many features have to be processed simultaneously, functional specialization is preserved. Our method thus opens a new way of brain mapping, which allows the localization of a multitude of brain areas based on a single experiment using uncontrolled, natural stimuli. Furthermore, our results show that the intensity of activity in a specialized area is linearly correlated with the intensity of its perceptual experience. This leads us to suggest that each specialized area is directly responsible for the creation of a feature-specific conscious percept (a microconsciousness). Hum. Brain Mapp. 21:75-83, 2004.
Adult↗