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PubMedDate not supplied

Cortical substrates supporting visual search in humans.

Serial and parallel visual search tasks were presented to patients with focal lesions in dorsolateral frontal, lateral parietal, or temporal-parietal cortex. In the unilateral display conditions, search efficiency in all patient groups was similar to the normal control group for stimuli both on the ipsi- and on the contralesional side of the displays. In contrast, in the bilateral display conditions, all patient groups showed a marked delay in initiating search on the side contralateral to the lesion as compared to normal controls. This delay was more pronounced when attention demands on the ipsilateral side increased, either by making target-distractor discrimination more difficult (serial search task), or by increasing the number of ipsilateral distractor items. The contralateral deficit was evident in all patient groups, supporting the notion that dorsolateral frontal as well as posterior parietal and temporal-parietal cortex plays a critical role in visual spatial attention.

Aged↗
PubMedDate not supplied

Using locations to store shape: an indirect effect of a lesion.

This study had three general points. First, it examined possible visual consequences of frontal lesions. A patient with focal damage to the subcortical regions of the left frontal lobe, and a small amount of damage near Broca's area, was predicted to have impaired brain function in posterior regions that are anatomically connected to the damaged site. Second, it showed the utility of using positron emission tomography (PET) in conjunction with magnetic resonance imaging to characterize "functional lesions." PET revealed reduced metabolism in posterior cortical loci that are innervated by fibers from the damaged regions. Some of the affected areas are hypothesized to be involved in visual functions, specifically the encoding of lines and edges. Third, a series of tests was designed to document that the patient had difficulty encoding visual stimuli, and then to distinguish among alternative possible causes of this deficit. The results suggested that the patient encoded shapes as sets of filled locations if possible, which allowed him to use intact processes subserved by brain areas that were not affected by the damage. The data were best explained if the lesion slowed processing in the ventral system (which encodes object properties), allowing the dorsal system (which encodes spatial properties) to produce a response more quickly than the ventral system.

Adult↗
PubMedDate not supplied

Visual memory, visual imagery, and visual recognition of large field patterns by the human brain: functional anatomy by positron emission tomography.

We measured the regional cerebral blood flow (rCBF) in 11 healthy volunteers with PET (positron emission tomography). The main purpose was to map the areas of the human brain that changed rCBF during (1) the storage, (2) retrieval from long-term memory, and (3) recognition of complex visual geometrical patterns. A control measurement was done with subjects at rest. Perception and learning of the patterns increased rCBF in V1 and 17 cortical fields located in the cuneus, the lingual, fusiform, inferior temporal, occipital, and angular gyri, the precuneus, and the posterior part of superior parietal lobules. In addition, rCBF increased in the anterior hippocampus, anterior cingulate gyrus, and in several fields in the prefrontal cortex. Recognition of the patterns increased rCBF in 18 identically located fields overlapping those activated in learning. In addition, recognition provoked differentially localized increases in the pulvinar, posterior hippocampus, and prefrontal cortex. Learning and recognition of the patterns thus activated identical visual regions, but different extravisual regions. A surprising finding was that the hippocampus was also active in recognition. Recall of the patterns from long-term memory was associated with rCBF increases in yet different fields in the prefrontal cortex, and the anterior cingulate cortex. In addition, the posterior inferior temporal lobe, the precuneus, the angular gyrus, and the posterior superior parietal lobule were activated, but not any spot within the occipital cortex. Activation of V1 or immediate visual association areas is not a prerequisite for visual imagery for the patterns. The only four fields activated in storage recall and recognition were those in the posterior inferior temporal lobe, the precuneus, the angular gyrus, and the posterior superior parietal lobule. These might be the storage sites for such visual patterns. If this is true, storage, retrieval, and recognition of complex visual patterns are mediated by higher-level visual areas. Thus, visual learning and recognition of the same patterns make use of identical visual areas, whereas retrieval of this material from the storage sites activates only a subset of the visual areas. The extravisual networks mediating storage, retrieval, and recognition differ, indicating that the ways by which the brain accesses the storage sites are different.

Adult↗
PubMed2025

MedImg: An Integrated Database for Public Medical Images.

The advancements in deep learning algorithms for medical image analysis have garnered significant attention in recent years. While several studies have shown promising results, with models achieving or even surpassing human performance, translating these advancements into clinical practice is still accompanied by various challenges. A primary obstacle lies in the availability of large-scale, well-characterized datasets for validating the generalization of approaches. To address this challenge, we curated a diverse collection of medical image datasets from multiple public sources, containing 105 datasets and a total of 1,995,671 images. These images span 14 modalities, including X-ray, computed tomography, magnetic resonance imaging, optical coherence tomography, ultrasound, and endoscopy, and originate from 13 organs, such as the lung, brain, eye, and heart. Subsequently, we constructed an online database, MedImg, which incorporates and systematically organizes these medical images to facilitate data accessibility. MedImg serves as an intuitive and open-access platform for facilitating research in deep learning-based medical image analysis, accessible at https://www.cuilab.cn/medimg/.

Humans↗
PubMed2002

Broiler skin and meat color changes during storage.

The importance of poultry skin and meat color (both absolute and variations in color) in the market place have been well established. It has also been reported that these colors change over time. With the development of computer-assisted vision grading systems, the changes in skin and meat color during and after processing have become important, based on calibrations and assessment values based on color. Four independent experiments were conducted to determine the pattern of color change in broiler skin and meat during processing and storage. Skin color change was measured on subscald (57 C) and semiscald (50 C) breast skin surfaces and on breast and leg meat, on the carcass and following deboning and packaging. A reflectance colorimeter was used to determine lightness (L*), redness (a*), and yellowness (b*) at 20-min intervals for the first 3 h, at 30-min intervals between 3 and 8 h, hourly between 8 and 12 h, and daily up to 8 d postmortem. Results clearly show that color values for both skin and meat changed dramatically for the first 6 h postmortem, after which the changes were less pronounced. The skin from semiscalded birds showed less change than the skin from subscalded birds. These results indicate that on-line vision systems need to take into account the dramatic changes in skin and meat color during the first 6 h postmortem, after which the color changes may be less important.

Animals↗
PubMed1990

Functional anatomy of storage, recall, and recognition of a visual pattern in man.

With the purpose of mapping the anatomical structures participating in memory of visual patterns, we measured regional cerebral blood flow (rCBF) as an indicator of synaptic metabolism in eleven volunteers during four conditions: rest, visual learning of colored geometrical patterns, recall with the eyes closed, and recognition of the patterns. Learning changed rCBF in the primary visual cortex, visual association areas, temporal pole, anterior hippocampus, dorsal thalamus, caudate nucleus, putamen, and the anterior cingulate cortex. Recall and recognition changed rCBF in other limbic, thalamic, and striatal sectors. Only the highest order parieto-occipital visual areas were activated during recall. These areas were assumed to be the storage sites. It was inferred that the limbic and striatal circuits participating in learning were replaced by other limbic and thalamic circuits to recall and recognize the learned patterns.

Adult↗
PubMed1998

Investigating form and colour perception in blindsight using an interference task.

Patients with striate cortical damage causing a hemianopic field defect can nevertheless demonstrate residual visual capacities in their blind field. Previous research investigating blindsight required patients to respond explicitly to stimuli appearing in the blind field by making forced choice judgements. We present data from a patient with a left occipital lesion resulting in a homonymous hemianopia, using the flanker task. This patient displayed a significant flanker congruency effect (FCE) for colour and letter stimuli even when they appeared in the blind field. A control patient with a lesion of the right thalamus showed no FCE in the blind field. This suggests that thalamo-extrastriate neural pathways are necessary for residual functioning in blindsight.

Aged↗
PubMed1990

Spontaneous hematic cysts of the orbit presenting with acute proptosis. A report of three cases.

Three cases of spontaneous hematic cyst of the orbit are described. All cases presented with acute onset of proptosis, conjunctival chemosis, choroidal folds, restricted ocular movement, and optic nerve compression syndrome with very poor vision. A computed tomography scan demonstrated a cystic lesion situated in the upper part of the orbit. Exploration revealed a cyst containing chocolate-colored fluid. Visual recovery was complete in two of three cases. There was no definite history of trauma in all three cases. Chronic hematic cysts have been described recently, but cases with acute onset such as ours have not to our knowledge been described clearly.

Acute Disease↗
PubMed1997

Nontraumatic orbital leptomeningeal cyst in an adult: case report.

To our knowledge, there is no reported case of visual disturbance associated with a nontraumatic orbital leptomeningeal cyst in the literature. We report the first such case and discuss the differential diagnosis of cystic lesions of the meninges that may be found on the surface of the brain.

Adult↗
PubMed1998

Spindle-cell lipoma of the preseptal eyelid.

An 82-year-old woman had experienced progressive enlargement of a long-standing left upper lid mass for 3 weeks. The superior visual field was compromised secondary to mechanical ptosis from this lid lesion. Computed tomography showed a large lid mass with a low density signal, similar to intraorbital fat. The tumor was completely excised. Histopathologic examination showed an encapsulated tumor composed of mature adipose tissue interspersed with fibrovascular septa containing spindle-cells, confirming a diagnosis of spindle-cell lipoma.

Aged↗
PubMed2000

Correlation of preoperative computed tomography and postoperative ocular motility in orbital blowout fractures.

PURPOSE: To determine a relationship between preoperative soft tissue disruption and postoperative ocular motility in orbital blowout fractures. METHODS: This retrospective cohort study reviewed 30 patients who met all criteria: retrievable coronal computed tomography (CT) scans; internal fractures of the orbital floor, with or without medial wall extension; preoperative diplopia; repair by a single surgeon; complete release of entrapped tissues; and postoperative binocular visual fields (BVFs). Motility outcomes were quantified by one group of the authors, who measured the vertical fusion within BVFs. Other authors analyzed CT scans, designating each fracture as either A or B, based on lesser or greater soft tissue distortion relative to the configuration of bone fragments. The interval between trauma and surgery was also determined. RESULTS: Among the 15 patients with a postoperative motility outcome poorer than the median (86 degrees or less), four (27%) had A fractures; 11 (73%) had B fractures. Among the 15 patients with an outcome better than the median (88 degrees or more), 10 (67%) had A fractures; five (33%) had B fractures. Differences were more defined away from the median. Among five patients with B fractures and better than the median result, three (60%) had surgical repair during the first week after injury. Among the 11 patients with B fractures and less than the median result, one (9%) had repair during the first week. CONCLUSIONS: Postoperative motility is influenced by soft tissue-bone fragment relationships. Whether the outcome can be altered by earlier surgery in selected cases will be determined by prospective studies.

Cohort Studies↗
PubMed2000

Secondary fractures of Le Fort I osteotomy.

PURPOSE: To report the ophthalmic complications of Le Fort I osteotomy for the correction of dentofacial deformities and to determine the maximal compressive loads applied during pterygomaxillary separation in a cadaver model. METHODS: Two cases of ophthalmic complications arising after Le Fort I osteotomy are reported. Le Fort I osteotomy was performed on five cadavers. The maximal compressive load applied during pterygomaxillary separation was recorded with a 10 kN (3,000 lbf) load cell of a MTS Mini-Bionix servo-hydraulic machine (MTS, Eden Prairie, MN, U.S.A.). A paired t test was used to compare forces applied to the right and left sides. Computed tomography scans of each specimen were obtained after Le Fort I osteotomy to document secondary fractures. The skulls were subsequently stained with 1% fuschin red to highlight secondary fractures. RESULTS: Maximum compressive loads during pterygomaxillary separation ranged from 22 N (5.0 lbf) to 162 N (36.5 lbf), with an average of 106 N (23.8 lbf) (SD 47.6 N [10.7 lbf]). Forces applied on the first operative side were significantly greater than forces applied on the second operative side (p = 0.0034). Secondary fractures were found in three specimens by computed tomography and in two specimens by 1% fuschin red. All secondary fractures occurred on the second operative side. CONCLUSION: Secondary fractures in the Le Fort I osteotomy procedures occurred on the side opposite the greater maximal compressive load and on the second operative side.

Adult↗
PubMed1999

Frequency-dependent changes in cerebral metabolic rate of oxygen during activation of human visual cortex.

To test the hypothesis that brain oxidative metabolism is significantly increased upon adequate stimulation, we varied the presentation of a visual stimulus to determine the frequency at which the metabolic response would be at maximum. The authors measured regional CMR(O2) in 12 healthy normal volunteers with the ECAT EXACT HR+ (CTI/Siemens, Knoxville, TN, U.S.A.) three-dimensional whole-body positron emission tomograph (PET). In seven successive activating conditions, subjects viewed a yellow-blue annular checkerboard reversing its contrast at frequencies of 0, 1, 4, 8, 16, 32, and 50 Hz. Stimulation began 4 minutes before and continued throughout the 3-minute dynamic scan. In the baseline condition, the subjects began fixating a cross hair 30 seconds before the scan and continued to do so for the duration of the 3-minute scan. At the start of each scan, the subjects inhaled 20 mCi of (15)O-O2 in a single breath. The CMR(O2) value was calculated using a two-compartment, weighted integration method. Normalized PET images were averaged across subjects and coregistered with the subjects' magnetic resonance imaging in stereotaxic space. Mean subtracted image volumes (activation minus baseline) of CMR(O2) then were obtained and converted to z statistic volumes. The authors found a statistically significant focal change of CMR(O2) in the striate cortex (x = 9; y = -89; z = -1) that reached a maximum at 4 Hz and dropped off sharply at higher stimulus frequencies.

Administration, Inhalation↗
PubMedDate not supplied

Subacute pituitary apoplexy: MR and CT appearance.

We report three cases of subacute hemorrhage into a pituitary adenoma. Two patients each had visual disturbance and hypopituitarism treated with corticosteroids. No patient received bromocriptine. Because it is more exact than CT in displaying the metabolic products of hemorrhage, magnetic resonance is the preferred modality for radiographic investigation of subacute or chronic pituitary apoplexy in patients with prolonged headache and visual disturbance.

Adolescent↗
PubMed1998

Endoscopic optic nerve decompression: the Graz experience.

Recommendations for management of traumatic injuries to the optic nerve in the literature include expectant management, medical therapy, surgical treatment, and medical therapy combined with surgical decompression. Traditional surgical approaches to optic nerve decompression (OND) are a neurosurgical or craniotomy approach, extranasal transethmoidal approach, transorbital approach, transantral approach, and intranasal microscopic approach. Recent advances in instrumentation and surgical techniques have made an endoscopic approach to OND possible. Since 1991 endonasal endoscopic decompression of the optic nerve has been the surgical approach of choice in patients requiring OND in the authors' hospital. The endoscopic method offers many advantages over the traditional approaches. Decreased morbidity, preservation of olfaction, rapid recovery time, more acceptable cosmetic results with no external scars, no risk of injury to the developing teeth in children, and less operative stress in a patient who may have multisystem trauma are only some of the benefits associated with the endoscopic OND. The authors' technique of endonasal endoscopic approach to OND, medical management, and indications for surgery and the results in 22 patients undergoing this procedure are discussed.

Adolescent↗