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Results for “Functional anatomy”

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At least 73 records · Page 4Linked to original sources
PubMed1999

Functional anatomy of pursuit eye movements in humans as revealed by fMRI.

We have investigated the functional anatomy of pursuit eye movements in humans with functional magnetic imaging. The performance of pursuit eye movements induced activations in the cortical eye fields also activated during the execution of visually guided saccadic eye movements, namely in the precentral cortex [frontal eye field (FEF)], the medial superior frontal cortex (supplementary eye field), the intraparietal cortex (parietal eye field), and the precuneus, and at the junction of occipital and temporal cortex (MT/MST) cortex. Pursuit-related areas could be distinguished from saccade-related areas both in terms of spatial extent and location. Pursuit-related areas were smaller than their saccade-related counterparts, three of eight significantly so. The pursuit-related FEF was usually inferior to saccade-related FEF. Other pursuit-related areas were consistently posterior to their saccade-related counterparts. The current findings provide the first functional imaging evidence for a distinction between two parallel cortical systems that subserve pursuit and saccadic eye movements in humans.

Adult↗
PubMed2003

Functional anatomy of the insula: new insights from imaging.

Little is known about the functional anatomy of the insula. Several experimental data suggest that the organization of the insular connections from the different insular cytoarchitectonic regions is related to different functional domains within the insula, and recent electrophysiological and neuroimaging studies have shown the existence of an anterior-posterior organization within the insular cortex. To further investigate this point, we carried out a positron emission tomography (PET) study using fluorodeoxyglucose ((18)F-FDG) in patients with medial temporal lobe epilepsy who experienced emotional or visceral symptoms that are supposed to be elicited in the insula. The aim of our study was to assess the existence of a functional insular somatotopic organization. FDG-PET studies were carried out in 18 epileptic patients. Data were analyzed using statistical parametric mapping (SPM96). The results showed that the emotional symptoms were correlated with hypometabolism in the anterior part of the ipsilateral insular cortex, while visceral symptoms were correlated with hypometabolism in the posterior part ( p=0.001). This neuroimaging study demonstrates that the anterior part of the insular cortex corresponding to the agranular cortex subserves emotional functions while the posterior part of the insular cortex corresponding to the granular cortex subserves ascending visceral symptoms.

Adolescent↗
PubMed2003

Functional anatomy of pitch memory--an fMRI study with sparse temporal sampling.

Auditory functional magnetic resonance imaging tasks are challenging since the MR scanner noise can interfere with the auditory stimulation. To avoid this interference a sparse temporal sampling method with a long repetition time (TR = 17 s) was used to explore the functional anatomy of pitch memory. Eighteen right-handed subjects listened to a sequence of sine-wave tones (4.6 s total duration) and were asked to make a decision (depending on a visual prompt) whether the last or second to last tone was the same or different as the first tone. An alternating button press condition served as a control. Sets of 24 axial slices were acquired with a variable delay time (between 0 and 6 s) between the end of the auditory stimulation and the MR acquisition. Individual imaging time points were combined into three clusters (0-2, 3-4, and 5-6 s after the end of the auditory stimulation) for the analysis. The analysis showed a dynamic activation pattern over time which involved the superior temporal gyrus, supramarginal gyrus, posterior dorsolateral frontal regions, superior parietal regions, and dorsolateral cerebellar regions bilaterally as well as the left inferior frontal gyrus. By regressing the performance score in the pitch memory task with task-related MR signal changes, the supramarginal gyrus (left>right) and the dorsolateral cerebellum (lobules V and VI, left>right) were significantly correlated with good task performance. The SMG and the dorsolateral cerebellum may play a critical role in short-term storage of pitch information and the continuous pitch discrimination necessary for performing this pitch memory task.

Adolescent↗
PubMed1990

Functional anatomy of the choroidal circulation: methyl methacrylate casting of human choroid.

The functional anatomy of the normal choroidal circulation in man is described from scanning electron microscopic examination of methyl methacrylate microvascular casts. Distal and para-optic short posterior ciliary arteries supply wedge-shaped areas of choroid. Regional variations in choriocapillary morphology are well recognised; the lobules are densely packed at the posterior pole with a high capillary to inter-capillary ratio. Choroidal capillaries are flattened providing a large surface area for metabolic exchange with the retinal pigment epithelium. In acute choroidal ischaemia (from a variety of systemic disease), wedge shaped choroidal lesions may correspond to occlusion of short posterior ciliary arteries and geographic or focal lesions to occlusion of choroidal arterioles or choriocapillary lobules.

Capillaries↗
PubMedDate not supplied

Visual pathways for object-oriented action and object recognition: functional anatomy with PET.

The purpose of this study was to identify the functional anatomy of the mechanisms involved in visually guided prehension and in object recognition in humans. The cerebral blood flow of seven subjects was investigated by positron emission tomography. Three conditions were performed using the same set of stimuli. In the 'grasping' condition, subjects were instructed to accurately grasp the objects. In the 'matching' condition, subjects were requested to compare the shape of the presented object with that of the previous one. In the 'pointing' condition (control), subjects pointed towards the objects. The comparison between grasping and pointing showed a regional cerebral blood flow (rCBF) increase in the anterior part of the inferior parietal cortex and part of the posterior parietal cortex. The comparison between grasping and matching showed an rCBF increase in the cerebellum, the left frontal cortex around the central sulcus, the mesial frontal cortex and the left inferior parietal cortex. Finally, the comparison between matching and pointing showed an rCBF increase in the right temporal cortex and the right posterior parietal cortex. Thus object-oriented action and object recognition activate a common posterior parietal area, suggesting that some kind of within-object spatial analysis was processed by this area whatever the goal of the task.

Adult↗
PubMed2006

The precuneus: a review of its functional anatomy and behavioural correlates.

Functional neuroimaging studies have started unravelling unexpected functional attributes for the posteromedial portion of the parietal lobe, the precuneus. This cortical area has traditionally received little attention, mainly because of its hidden location and the virtual absence of focal lesion studies. However, recent functional imaging findings in healthy subjects suggest a central role for the precuneus in a wide spectrum of highly integrated tasks, including visuo-spatial imagery, episodic memory retrieval and self-processing operations, namely first-person perspective taking and an experience of agency. Furthermore, precuneus and surrounding posteromedial areas are amongst the brain structures displaying the highest resting metabolic rates (hot spots) and are characterized by transient decreases in the tonic activity during engagement in non-self-referential goal-directed actions (default mode of brain function). Therefore, it has recently been proposed that precuneus is involved in the interwoven network of the neural correlates of self-consciousness, engaged in self-related mental representations during rest. This hypothesis is consistent with the selective hypometabolism in the posteromedial cortex reported in a wide range of altered conscious states, such as sleep, drug-induced anaesthesia and vegetative states. This review summarizes the current knowledge about the macroscopic and microscopic anatomy of precuneus, together with its wide-spread connectivity with both cortical and subcortical structures, as shown by connectional and neurophysiological findings in non-human primates, and links these notions with the multifaceted spectrum of its behavioural correlates. By means of a critical analysis of precuneus activation patterns in response to different mental tasks, this paper provides a useful conceptual framework for matching the functional imaging findings with the specific role(s) played by this structure in the higher-order cognitive functions in which it has been implicated. Specifically, activation patterns appear to converge with anatomical and connectivity data in providing preliminary evidence for a functional subdivision within the precuneus into an anterior region, involved in self-centred mental imagery strategies, and a posterior region, subserving successful episodic memory retrieval.

Animals↗
PubMed1993

Functional anatomy of the shoulder complex.

Recent research findings are incorporated in this review of the functional anatomy of the shoulder complex. The scapulothoracic mechanism is described, including a review of scapular motion and the structure and function of the sternoclavicular and acromioclavicular joints. New information regarding the resting position of the scapula on the thorax and the effect of aging and spinal posture on position has been presented. In the second part of the paper, the anatomy of the glenohumeral joint is reviewed, with emphasis on the articular, periarticular, and muscular mechanisms responsible for stability of this articulation. The article concludes with a discussion of the integrated function of the scapulothoracic and glenohumeral articulations in upper extremity elevation.

Acromioclavicular Joint↗
PubMed1998

Functional anatomy of cavernous helicine arterioles in potent subjects.

PURPOSE: We investigated the morphological and functional features of cavernous helicine arterioles in male potent subjects. MATERIALS AND METHODS: Ten young men reporting normal rigid erections which were confirmed by polysomnographic recording underwent power Doppler sonography of the cavernous helicine arterioles during flaccidity, after intracavernous injection of alprostadil, and after subsequent genital and audiovisual sexual stimulation. RESULTS: During flaccidity the helicine arterioles were never detected by power Doppler imaging while they became evident in all cases after alprostadil injection. They usually originated from the cavernous artery forming an acute angle and showed 3 orders of ramifications. Systolic and diastolic flow was present. After genital and audiovisual sexual stimulation, and achievement of maximum rigidity, the helicine arterioles were still evident but with only 1 or 2 orders of distal ramifications. Only systolic flow was present. During penile tumescence the helicine arterioles disappeared in all cases. CONCLUSIONS: Using power Doppler sonography it is possible to investigate the functional anatomy of the cavernous helicine arterioles during the various phases of the erectile cycle. Our preliminary study suggests that the helicine arterioles are functionally inactive during penile flaccidity while they are activated during penile tumescence and continue to supply blood to the corpora also during maximum penile rigidity.

Adult↗
PubMed1999

Functional Anatomy of the Interosseous Membrane of the Forearm - Dynamic Changes During Rotation.

The functional anatomy of the interosseous membrane (IOM) of the forearm was studied in 15 fresh frozen cadavers. The IOM consisted of three components: the tendinous part; the membranous part; and the dorsal oblique accessory cord. The tendinous part was a thick and strong complex of three to ten bundles which run from the proximal one third of the radius to the distal quarter of the ulna. The membranous part was recognised as a soft and thin structure, adjacent proximal and distal to the tendinous part. The dorsal oblique cord was found as a single cord on the dorsal side of the IOM from the proximal quarter of the ulna to the middle region of the radius. This cord was distinct from the oblique cord, which existed on the palmar side of the forearm separated from the IOM. The IOM was flat in the neutral position, while it flexed along the rotation axis in pronation and supination. Since the prominence of the curvature in the IOM was almost in the same direction as the fibres of the tendinous part, the tendinous part demonstrated only bending, similar to partial bending of an elastic board. The bending position was changed with the forearm position and the tightened bundles in the tendinous part were altered during rotation.

Journal Article↗
PubMedDate not supplied

[Functional anatomy of the cerebral cortex implicated in visual processing].

INTRODUCTION AND OBJECTIVE: The functional anatomy of the cerebral cortex implicated in vision is reviewed with the purpose of illustrating the complexity of the cortical processing in visual perception. DEVELOPMENT: A brief analysis of the retinogeniculocortical pathway is presented and a summary of the main findings of the physiological and anatomical studies of Hubel and Wiesel in the adult brain is also illustrated. Special attention is paid in showing the visual pathways for object and face recognition as well as spatial cognition. CONCLUSIONS: Visual cortical areas in primates and man can be divided roughly into a ventral stream in relation with the temporal lobe responsible for the processing and storage of information about the identity of objects, their shape, color, and other salient physical features; and a dorsal stream in relation with the parietal lobe and concerned with the analysis of the locations of objects, and their movements in space. These two cortical pathways are not totally segregated and both are related to the prefrontal cortex as well as other subcortical structures such as the thalamus, the basal ganglia, the superior colliculus and the cerebellum through the pontine nuclei.

Cerebral Cortex↗
PubMed1998

The functional anatomy of attention to visual motion. A functional MRI study.

Attention can enhance or modulate neural responses to stimuli at early and late stages of sensory processing. We were interested in the modulatory effect of attention to visual motion on cortical responses as measured by functional MRI. Subjects were scanned during repeated presentations of identical stimuli (visual motion) while only the attentional component of the task was varied. Enhanced haemodynamic responses during attentive conditions defined an occipitoparietofrontal system, including sensory and association areas, as well as the medial thalamus and superior colliculus. Attentional modulation was not restricted to extrastriate areas (including V3a and the V5 complex) but was also evident, to a lesser degree, in early visual areas close to the calcarine fissure (V1/V2 border). Attention-related enhancement of cortical responsiveness is discussed in terms of data that implicate modulatory short-term changes in synaptic efficacy and reciprocal connections between striate, extrastriate, parietal and frontal areas. Given the similarity of our attentional network to that controlling eye movements, the results of this study are in accord with theories linking oculomotor control and attention.

Attention↗
PubMed1994

Functional anatomy and physiology of the female breast.

As mammals, we define our biologic class by the function of the breast in nourishing our young. As obstetricians, we seek to enhance or diminish function; as gynecologists, the appearance of inappropriate lactation (galactorrhea) may signify serious disease. In this article, development, differentiation, and functional anatomy of the breast is discussed. The hormonal interactions responsible for these events and the physiologic function of this vital reproductive organ during the life cycle of the woman is emphasized.

Breast↗
PubMed1992

Functional anatomy of human procedural learning determined with regional cerebral blood flow and PET.

The functional anatomy of motor skill acquisition was investigated in six normal human subjects who learned to perform a pursuit rotor task with their dominant right hand during serial positron emission tomography (PET) imaging of relative cerebral blood flow (relCBF). The effect of motor execution, rather than learning, was identified by a comparison of four motor performance scans with two control scans (eye movements only). Motor execution was associated with activation of a distributed network involving cortical, striatonigral, and cerebellar sites. Second, the effect of early motor learning was examined. Performance improved from 17% to 66% mean time on target across the four PET scans obtained during pursuit rotor performance. Across the same scans, significant longitudinal increases of relCBF were located in the left primary motor cortex, the left supplementary motor area, and the left pulvinar thalamus. The results demonstrate that changes of regional cerebral activity associated with early learning of skilled movements occur in sites that are a subset of a more widely distributed network that is active during motor execution.

Adult↗
PubMedDate not supplied

[The functional anatomy of the eye with its impact on immunopathology].

The description of specific eye's functional anatomy from an immunological point of view helps us in better understanding the particularities of immunitary reaction at this level. Unlike the globe appendices (lid, conjunctive and lacrimal apparatus), where the immunitary defense has no particularities, the ocular globe is distinguished by the existence of the hemato-ocular barriers, the absence of lymphatic drainage and the unequal distribution of HLA phenomena in ocular tissues.

Antibody Formation↗
PubMed1977

Functional anatomy of the deep motor branch of the ulnar nerve.

Our presently inadequate knowledge of the functional anatomy of the deep branch of the ulnar nerve handicaps our management of ulnar nerve lesions. The extensive anatomical variations in the distribution of this nerve preclude adherence to a textbook pattern of innervation. Electrophysiological recordings of single sensory fibers in monkeys along with fascicular stimulation studies provided novel information about the functional organization of the deep branch of the ulnar nerve: (1) there is a wide range of sensory fibers not currently recognized by textbook descriptions; (2) the innervation pattern is far more diffuse and covers greater areas than previously suspected; (3) at the distal forearm level the motor component of the deep ulnar branch is distributed throughout the entire ulnar nerve and is not restricted to specific fascicles; (4) contrary to previous assumptions, the deep branch of the ulnar nerve is mixed, and not purely motor. In fact, it may be mostly sensory. Afferent fibers arise from muscle, joints, deep subcutaneous tissues and even skin. These findings suggest that it is unwise to look at any nerve as purely motor or having a set innervation pattern, and emphasize the pressing need for objective preoperative and/or intraoperative functional assessment in peripheral nerve surgery.

Animals↗
PubMed1997

Functional anatomy of human auditory attention studied with PET.

Positron emission tomography was used to investigate the functional anatomy of selective auditory attention in 17 right-handed male volunteers who submitted to different tasks: silent rest (REST) listening to frequent low- or rare high-pitched tones (LIS) delivered randomly to the right or the left ear, selective auditory attention where subjects had to attend to deviants in one ear, right (ATTR) or left (ATTL). Six subjects had the series REST, LIS, ATTR twice, eight subjects the series REST, LIS, ATTL, and the last three subjects the sereis REST, ATTR, ATTL. Event-related potentials were simultaneously recorded with PET and showed significant task and electrode site effects on the N100 amplitude. When compared to REST, LIS elicited bilateral temporal activations of the Heschl's gyri and the planum temporale, with a significant rightward asymmetry, and of the posterior part of the superior temporal gyrus. Significant right precentral and anterior cingulate gyri normalized regional cerebral blood flow increases were observed in the frontal lobe. Both the ATTR and the ATTL conditions, compared to LIS, activated the supplementary motor area, bilateral precentral, and left postcentral cortices without any temporal cortex activation. In addition, the ATTL condition resulted in a right prefrontal cortex activation. Pooling the 14 subjects revealed an asymmetry in the superior temporal gyrus favoring the cortex contralateral to the attended ear. Two major networks seem thus to be involved during selective auditory attention: (1) a local temporal network, on which selective attention produces a modulation of the functional lateralization, and (2) a frontal network that could mediate the temporal cortex modulation by attention.

Adult↗
PubMed2006

Relationship between spatial abilities, mental rotation and functional anatomy learning.

This study investigated the relationship between visuo-spatial representation, mental rotation (MR) and functional anatomy examination results. A total of 184 students completed the Group Embedded Figures Test (GEFT), Mental Rotation Test (MRT) and Gordon Test of Visual Imagery Control. The time spent on personal assignment was also considered. Men were found to score better than women on both GEFT and MRT, but the gender effect was limited to the interaction with MRT ability in the anatomy learning process. Significant correlations were found between visuo-spatial, MR abilities, and anatomy examination results. Data resulting from the best students' analyzes underscore the effect of high MR ability which may be considered reliable predictor of success in learning anatomy. The use of specific tests during learning sessions may facilitate the acquisition of anatomical knowledge.

Adolescent↗