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PubMed2003

Approaching an ecologically valid functional anatomy of spontaneous "willed" action.

We used functional magnetic resonance imaging of healthy subjects to investigate the neural basis for spontaneous "willed" action. We hypothesised that such action involves prefrontal cortex (PFC) and supplementary motor area (SMA), in addition to primary motor cortex. Furthermore, we predicted that PFC and SMA would demonstrate similar temporal response dynamics, distinct from primary motor cortex. Specifically, we predicted earlier activation in PFC and SMA, manifest as shorter response latencies compared with primary motor cortex. Six right-handed males participated in an event-related design and were required to generate spontaneous motor acts inside the scanner. By deciding "which" of two buttons to press, and "when" to press them, subjects generated sequences of action that were of high information content ("novelty" or "randomness"). Utilising a short repetition time (1 s), we acquired functional images that covered most of the frontal and parietal cortices. The onset of action was associated with significant activation in bilateral PFC, left primary motor cortex, and, close to the midline, SMA. Following action, mean time to half-maximum blood oxygenation level-dependent response was significantly earlier in left PFC and SMA than primary motor cortex. Our findings suggest that neural correlates of spontaneous willed action are distributed in executive and motor centres, and that temporal response dynamics differentiate "higher" regions from subordinate motor areas.

Adult↗

PubMed1975

[Functional anatomy of the superfical temporal blood vessels].

Functional study on superficial temporal vessels. These vessels appear to have a board territory on--the horizontal part of the scalp--the superior lateral face--the anterior and superior half of the external ear The terminal part of these vessels and the rich anastomotic system is particularly studied. This system passes the middle line; the anastomoses are in the fascia superficilialis. Secondly there is a sub-dermal plexual formation which is in a parallel direction to the vessels. Practical consequences can be found--in neuro-surgery--in plastic-surgery--and in the new surgery of cutaneous transfer with micro-anastomoses of the vessels.

Arteries↗

PubMed2001

A computational model of action selection in the basal ganglia. I. A new functional anatomy.

We present a biologically plausible model of processing intrinsic to the basal ganglia based on the computational premise that action selection is a primary role of these central brain structures. By encoding the propensity for selecting a given action in a scalar value (the salience), it is shown that action selection may be recast in terms of signal selection. The generic properties of signal selection are defined and neural networks for this type of computation examined. A comparison between these networks and basal ganglia anatomy leads to a novel functional decomposition of the basal ganglia architecture into 'selection' and 'control' pathways. The former pathway performs the selection per se via a feedforward off-centre on-surround network. The control pathway regulates the action of the selection pathway to ensure its effective operation, and synergistically complements its dopaminergic modulation. The model contrasts with the prevailing functional segregation of basal ganglia into 'direct' and 'indirect' pathways.

Animals↗

PubMed1983

Functional anatomy of the tectum mesencephali of the goldfish. An explorative analysis of the functional implications of the laminar structural organization of the tectum.

The present paper is aimed at an exploration of the possible functional significance of the laminar organization of the goldfish tectum at both the cellular and the synaptic level. For this purpose (1) the data concerning the structure of the teleostean tectum are surveyed, (2) a conceptual framework of the intratectal connectivity in the goldfish is proposed, (3) the electrophysiological data concerning the teleosteam tectum are surveyed and (4) the degree of correlation between the structural and physiological data available is discussed. Apart from the retina, tectal afferents originate from at least 10 other brain centers. At least 5 of these projections appear to be topographically organized. Tectal afferents, neurons as well as synapses reveal a characteristic intratectal lamination pattern. Tectal efferents project to at least 10 brain centers, and have until now been shown to arise from 6 cell types. The structural data surveyed allow the construction of a conceptual framework of tectal circuitry on the basis of 3 starting points. (1) The existence of at least 8 presynaptic zones or laminae, each containing a characteristic set of presynaptic structures (afferents and axons of interneurons). (2) The fact that the tectal postsynaptic structures (somata and dendrites of tectal neurons) each have a characteristic location, extension and synaptic density, which determines the relative importance of the different presynaptic zones for each cell type. (3) The laminar specificity hypothesis, which implies that presynaptic structures that coexist in a particular presynaptic zone terminate without preference on all types of postsynaptic structures within that zone. The conceptual framework of tectal circuitry is quantified in terms of connectivity index and connective importance. Analysis of the framework constructed leads to a detailed description of the intratectal pathways involved in the processing of the 4 main streams of tectal input (i.e. visual, toral, telencephalic and 'deep' input). It was concluded that the laminar organization of the tectum is primarily relevant for multimodal integration and that the tectal cell types each receive a characteristic sample out of the multimodal information available in the different tectal layers.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1999

Importance of the mitral subvalvular apparatus for left ventricular functional anatomy.

The mitral subvalvular apparatus is so important to attain the integrity of the left ventricular geometric model and systolic pump function of the heart. We conducted a detailed dissection of the anatomic structure of mitral valve complex and left ventricle of 10 adult hearts from fixed human cadavers (eight male and two female) at Department of Anatomy. Faculty of Medicine of Istanbul University and Department of Cardiovascular Surgery, Koşuyolu Heart and Research Hospital. The distribution of chordae tendinea and classification of musculus papillaris were recorded. The distribution of chordae tendinea varied slightly both anterior and posterior groups. Musculus papillaris was not simetrical in all subjects. Four type of musculus papillaris were distinguished. The insertio angulus of musculus papillaris varied between 20 degrees and 55 degrees. The left ventricular distances (inflow-outflow) and axes (short-long) were determined as the criteria, together with the mitral subvalvular apparatus, to gain the architecture of the left ventricle. We believe that the goal a more precise data collection and developed model will influence our understanding of functional anatomy of left ventricular subvalvular apparatus, and concept of changes in left ventricular configuration after mitral valve surgery.

Adult↗

PubMed1996

Functional anatomy of the organs of micturition.

The anatomy of the organs of micturition has been the subject of study for nearly 150 years. As a result of advances in techniques and methods of clinical and research investigation, studies over the past three decades have intensified and have been increasingly directed at the functional implications and significance of organ anatomy and structure. This has led to revision of many traditional ideas about micturition and the development of new viewpoints and modalities for study of its disorders. This article summarizes the evolution of our thinking and understanding of the functional anatomy of the bladder and urethra over the years, and suggests possible directions for continued clinical study and investigation.

Female↗

PubMed2000

Functional anatomy of movement disorders.

Models of basal ganglia function are described which encapsulate the principal pathophysiological mechanisms underlying parkinsonian akinesia on the one hand and abnormal involuntary movement disorders (dyskinesias) on the other. In Parkinson's disease, degeneration of the nigrostriatal dopamine system leads to overactivity of the 'indirect' striatopallidal projection to the lateral (external) segment of the globus pallidus. This causes inhibition of lateral pallidal neurons, which in turn project to the subthalamic nucleus. Disinhibition of the subthalamic nucleus leads to abnormal subthalamic overactivity and, as a consequence, overactivity of medial (internal) pallidal output neurons. Dyskinesias, such as are observed in Huntington's disease, levodopa-induced dyskinesia and ballism, share mechanistic features in common and are associated with decreased neuronal activity in both the subthalamic nucleus and the medial globus pallidus.

Animals↗

PubMed2004

Functional anatomy of motor recovery after early brain damage.

Functional magnetic resonance imaging and transcranial magnetic stimulation were used to examine a 34 year-old right-handed patient, who, at the age of 6 years, had experienced sudden right hemiplegia, seizures, and stupor during a bout of measles encephalitis, followed by incomplete distal right motor recovery. Morphological MRI showed massive unilateral enlargement of the left ventricle, associated with extreme thinning of the white and gray matter,with partial preservation of the pyramidal tract. Functional MRI and transcranial magnetic stimulation revealed reorganization of the motor cortices, and integrity of the corticospinal pathway, respectively. Our findings indicate that complete hand motor recovery may require functional connections between the motor cortical areas and cortical-subcortical structures, in addition to the retained integrity of the primary sensorimotor area and pyramidal tract.

Adult↗

PubMed2002

Impact of fMRI acoustic noise on the functional anatomy of visual mental imagery.

One drawback of functional magnetic resonance imaging (fMRI) is that the subject must endure intense noise during testing. We examined the possible role of such noise on the activation of early visual cortex during visual mental imagery. We postulated that noise may require subjects to work harder to pay attention to the task, which in turn could alter the activation pattern found in a silent environment. To test this hypothesis, we used positron emission tomography (PET) to monitor regional Cerebral Blood Flow (rCBF) of six subjects while they performed an imagery task either in a silent environment or in an "fMRI-like" noisy environment. Both noisy and silent imagery conditions, as compared to their respective baselines, resulted in activation of a bilateral fronto-parietal network (related to spatial processing), a bilateral inferior temporal area (related to shape processing), and deactivation of anterior calcarine cortex. Among the visual areas, rCBF increased in the most posterior part of the calcarine cortex, but at level just below the statistical threshold. However, blood flow values in the calcarine cortex during the silent imagery condition (but not the noisy imagery condition) were strongly negatively correlated with accuracy; the more challenging subjects found the task, the more strongly the calcarine cortex was activated. The subjects made more errors in the noisy condition than in the silent condition, and a direct comparison of the two conditions revealed that noise resulted in an increase in rCBF in the anterior cingulate cortex (involved in performance monitoring) and in the Wernicke's area (required to encode the verbal cues used in the task). These results thus demonstrate a nonadditive effect of fMRI gradient noise, resulting in a slight but significant effect on both performance and the neural activation pattern.

Adult↗

PubMed2000

[Functional anatomy of the third ventricle. Neuropsychological data].

The functional structures surrounding the third ventricle explain the occurrence of neuropsychological disorders when a tumor develops in this area. The functional environment of the third ventricle is involved in memory, motor executive control, endocrine and vegetative regulations. The types of memory deficit, the behavioural and emotional regulations, the interhemispheric transfer, and the regulation of executive functions are analyzed and correlated to the concerned anatomical structures. The review of the literature collected few specific considerations in neuropsychological dysfunctions occurring with tumors of the third ventricle. A retrospective study was conducted in 17 patients of the national series operated on for a third ventricle lesion : long-term memory and executive functions were frequently impaired in the patients, and the deficits were underestimated by usual follow-up. More systematic utilization of preoperative and postoperative test batteries is necessary for a better evaluation of neuropsychological disorders after third ventricle surgery.

Adolescent↗

PubMed1985

Some new aspects of the functional anatomy of the shoulder.

The authors investigated the functional role of the shoulder muscles in various active movements using simultaneous polymyographic recordings. Ten muscles were investigated in both normal subjects and in patients with pathological conditions. Ten patients were also studied during the course of operations for nonrelated conditions by "tetanizing" stimulation of nerves to individual muscles to determine their action as single muscles.

Adult↗

PubMed1988

Functional anatomy of the larynx.

The larynx serves three basic functions in humans. In order of functional priority they are protective, respiratory, and phonatory. This article discusses these three roles in terms of phylogeny, developmental anatomy, and neuromuscular reflex activity.

Animals↗

PubMed1997

Functional anatomy of the extensor tendons of the digits.

The complexity and intricacy of hand function are reflected by the anatomy. Extensor muscles have a relatively consistent architecture but also have notable anatomic variations of their tendons, particularly on the ulnar side of the hand. The extensor tendons, juncturae tendinum, intertendinous fascia, and soft tissue function as a plexiform construct to provide stability during power grip and allow for laxity in performing independent fine finger tasks. The greater independence of index finger motion relates to its two tendons, one (EDC-index) with a thin transverse juncturae tendinum, the other (EIP) without a junctural connection. It is also more independent because of a more mobile metatarsal, and because it is confined by only one web. The first dorsal interosseous also functions to rotate the index finger. The lumbrical to the index finger has only a single origin on the flexor profundus tendon. The elaborate tendon plexus on the dorsum of the hand is repeated in the complexity of the dorsal aponeurosis on the dorsum of the fingers. Finger motion is a balance of flexor muscles and intrinsics and extensor muscles that provides incredible versatility. This versatility and delicate balance of function is easily jeopardized by trauma and disease. The hand is among the most frequently injured parts of the body. An appreciation and understanding of its complex anatomy is of importance to hand assessment, repair, and reconstruction.

Fingers↗

PubMed1996

Functional anatomy of the human ureterovesical junction.

BACKGROUND: The valve function of the ureterovesical-junction (UVJ) is responsible for protection of the low pressure upper urinary tract from the refluxing of urine from the bladder. Controversy about the microanatomy of the human ureterovesical-junction persists. METHODS: Ten (3 male and 7 female) fresh cadaveric bladders (mean age 70 years old) were studied. The bladders were fixed within 24 hours postmortem, frozen, and serially sectioned. Acetyl- and butyryl- (nonspecific) cholinesterase activity were visualised as described by Karnovsky and Roots. The three-dimensional distribution of the different muscle groups participating in the formation of the UVJ was reconstructed. RESULTS: Three different muscle groups were identified: (1) the detrusor muscle and the deep trigone were mainly acetylcholinesterase-positive, (2) the inner and outer layer of the ureteric muscle were butyrylcholinesterase-positive and merged into a single longitudinal layer at the level of the UVJ and form the superficial trigone distally to the ureteric orifices, and (3) the muscularis mucosae is a discontinuous butyrylcholinesterase-positive layer in the bladder that is absent from the trigone. No evidence of any muscular connection was found between the ureter and bladder musculature. CONCLUSIONS: The anatomy of the UVJ as observed by us suggests the following model of the ureteric peristalsis. The urine bolus arrives in the ureteric lumen at the UVJ level. The ureter can only shorten its length, slides freely in its tunnel, and discharges the urine bolus in the bladder cavity. Ureteric constriction due to the peristalsis and thickening of the contracted portion of the ureter prevents the upstream leakage. Distal spreading of the ureteric "peristalsis" in the superficial trigone increases the submucosal ureteric length and prevents reflux.

Acetylcholinesterase↗

PubMed2002

Functional anatomy of intra- and cross-modal lexical tasks.

Functional magnetic resonance imaging (fMRI) was used to examine lexical processing in normal adults (20-35 years). Two tasks required only intramodal processing (spelling judgments with visual input and rhyming judgments with auditory input) and two tasks required cross-modal processing between phonologic and orthographic representations (spelling judgments with auditory input and rhyming judgments with visual input). Each task led to greater activation in the unimodal association area concordant with the modality of input, namely fusiform gyrus (BA 19, 37) for written words and superior temporal gyrus (BA 22, 42) for spoken words. Cross-modal tasks generated greater activation in posterior heteromodal regions including the supramarginal and angular gyri (BA 40, 39). Cross-modal tasks generated additional activation in unimodal areas representing the target of conversion, superior temporal gyrus for visual rhyming and fusiform gyrus for auditory spelling. Our findings suggest that the fusiform gyrus processes orthographic word forms, the superior temporal gyrus processes phonologic word forms, and posterior heteromodal regions are involved in the conversion between orthography and phonology.

Adult↗

PubMed1994

Visual form discrimination from luminance or disparity cues: functional anatomy by PET.

With the purpose of elucidating the functional fields involved in the discrimination of visual form based either on luminance or binocular disparity cues, we used PET to measure changes in regional cerebral blood flow (rCBF) in ten volunteers while they performed visual discrimination tasks. The averaged standardized subtraction images (delta rCBF) were analysed for statistically significant changes between the form tasks and their reference tasks. Twenty cortical fields in the visual association areas and the prefrontal cortex were engaged by the discrimination of visual form based upon disparity cues, whereas only four fields showed increased activity during the discrimination of visual form created by luminance cues. The only functional field activated in both conditions was in the left fusiform gyrus. The present findings extend our earlier observations, namely that disparate functional networks of activated fields in the human brain can perform the discrimination of visual form perceptually defined by different visual cues.

Adult↗

PubMed1998

The functional anatomy of imagining and perceiving colour.

We report two functional magnetic resonance imaging experiments which reveal similarities and differences between perceptual and imaginal networks within the single visual submodality of colour. The first experiment contrasted viewing of a coloured and grey-scale Mondrian display, while the second contrasted a relative colour judgement with a spatial task and required the generation of mental images. Our results show that colour perception activates the posterior fusiform gyrus bilaterally (area V4), plus right-sided anterior fusiform and lingual gyri, striate cortex (area V1), and the left and right insula. Colour imagery activated right anterior fusiform gyrus, left insula, right hippocampus and parahippocampal gyrus, but not V4 or V1. The findings reconcile neurological case studies suggesting a double dissociation between deficits in colour imagery and perception and point to anterior fusiform, parahippocampal gyri and hippocampus as the location for stored representations of coloured objects.

Brain Mapping↗

PubMed2004

[Functional anatomy of rectum and anus].

The anatomical structures of the rectum and anus are a functional unit designed to maintain continence mechanism. A pure anatomical description often fails to delineate this critical functional interaction. The topographic anatomy of the anorectum must be combined with an understanding of the mechanisms of anal continence and defecation, which can be transferred to clinical and especially surgical practice. The feedback-controlled reflex system of continence must be understood; it hinges on a complex interaction between the somatic and autonomic nervous systems.

Anal Canal↗