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1.
Appl Radiat Isot ; 69(12): 1721-4, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21367607

ABSTRACT

Clear cell sarcoma (CCS) is a rare melanocytic malignant tumor with a poor prognosis. Our previous study demonstrated that in vitro cultured CCS cells have the ability to highly uptake l-BPA and thus boron neutron capture therapy could be a new option for CCS treatment. This paper proved that a remarkably high accumulation of (10)B (45-74 ppm) in tumor was obtained even in a CCS-bearing animal with a well-controlled biodistribution followed by intravenous administration of L-BPA-fructose complex (500 mg BPA/kg).


Subject(s)
Boron Compounds/pharmacokinetics , Boron Neutron Capture Therapy , Phenylalanine/analogs & derivatives , Sarcoma, Clear Cell/radiotherapy , Adolescent , Animals , Cell Line, Tumor , Female , Humans , Mice , Mice, Inbred BALB C , Mice, Nude , Phenylalanine/pharmacokinetics , Sarcoma, Clear Cell/metabolism , Tissue Distribution
2.
Appl Radiat Isot ; 69(12): 1713-6, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21354804

ABSTRACT

Clear cell sarcoma (CCS), a rare malignant tumor with a predilection for young adults, is of poor prognosis. Recently however, boron neutron capture therapy (BNCT) with the use of p-borono-L-phenylalanine (BPA) for malignant melanoma has provided good results. CCS also produces melanin; therefore, the uptake of BPA is the key to the application of BNCT to CCS. We describe, for the first time, the high accumulation of boron in CCS and the CCS tumor-bearing animal model generated for BNCT studies.


Subject(s)
Boron Compounds/pharmacokinetics , Boron Neutron Capture Therapy , Phenylalanine/analogs & derivatives , Sarcoma, Clear Cell/metabolism , Animals , Cell Line, Tumor , Humans , In Vitro Techniques , Melanoma, Experimental/metabolism , Microscopy, Electron , Phenylalanine/pharmacokinetics
3.
Endoscopy ; 41(11): 929-33, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19802774

ABSTRACT

BACKGROUND AND STUDY AIMS: In recent years, endoscopic submucosal dissection (ESD) has been applied for the treatment of gastric tumors, and the en-bloc resection rate of early gastric cancer has greatly improved. Herein, we introduce spring-assisted ESD, for quicker submucosal dissection. PATIENTS AND METHODS: ESD was carried out in 32 patients (20 men, 12 women; mean age 72.6 years, range 53 - 88 years) for early gastric cancer, with tumors over 10 mm in diameter. The patients were divided retrospectively into two groups (spring-assisted ESD, n = 20; conventional ESD, n = 12). To comparatively evaluate the performance speed of ESD, the circumferential length and the area of the resected specimen were calculated by the approximation formula for ellipse. Then, the circumferential cutting speed, the submucosal dissection speed, and the total ESD speed were calculated as index scores. The scores for spring-assisted ESD and conventional ESD were compared. RESULTS: The mean (+/-SD) circumferential cutting speeds in spring-assisted ESD and conventional ESD were 0.53 +/- 0.27 and 0.60 +/- 0.30 cm/minute, respectively ( P = 0.51). The mean submucosal dissection speeds in spring-assisted ESD and conventional ESD were 0.67 +/- 0.41 and 0.32 +/- 0.24 cm (2)/minute, respectively ( P = 0.005). The mean total ESD speeds in spring-assisted ESD and conventional ESD were 0.25 +/- 0.10 and 0.17 +/- 0.07 cm (2)/minute, respectively ( P = 0.015). The mean total ESD times were 57 and 75 minutes in the spring and conventional group, respectively ( P = 0.30). CONCLUSION: Using the aforementioned indices, we evaluated the performance speed of ESD. Spring-assisted ESD may allow faster submucosal dissection.


Subject(s)
Dissection/instrumentation , Dissection/methods , Gastric Mucosa/surgery , Gastroscopy/methods , Stomach Neoplasms/surgery , Aged , Aged, 80 and over , Female , Gastroscopes , Humans , Male , Middle Aged , Treatment Outcome
4.
Appl Radiat Isot ; 67(7-8 Suppl): S355-8, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19386506

ABSTRACT

Neutron-capture therapy with gadolinium (Gd-NCT) has therapeutic potential, especially that gadolinium is generally used as a contrast medium in magnetic resonance imaging (MRI). The accumulation of gadolinium in a human sarcoma cell line, malignant fibrosis histiocytoma (MFH) Nara-H, was visualized by the MRI system. The commercially available MRI contrast medium Gd-DTPA (Magnevist, dimeglumine gadopentetate aqueous solution) and the biodegradable and highly gadopentetic acid (Gd-DTPA)-loaded chitosan nanoparticles (Gd-nanoCPs) were prepared as MRI contrast agents. The MFH cells were cultured and collected into three falcon tubes that were set into the 3-tesra MRI system to acquire signal intensities from each pellet by the spin echo method, and the longitudinal relaxation time (T1) was calculated. The amount of Gd in the sample was measured by inductively coupled plasma atomic emission spectrography (ICP-AES). The accumulation of gadolinium in cells treated with Gd-nanoCPs was larger than that in cells treated with Gd-DTPA. In contrast, and compared with the control, Gd-DTPA was more effective than Gd-nanoCPs in reducing T1, suggesting that the larger accumulation exerted the adverse effect of lowering the enhancement of MRI. Further studies are warranted to gain insight into the therapeutic potential of Gd-NCT.


Subject(s)
Contrast Media , Gadolinium/therapeutic use , Histiocytoma, Malignant Fibrous/diagnosis , Histiocytoma, Malignant Fibrous/radiotherapy , Magnetic Resonance Imaging , Neutron Capture Therapy/methods , Cell Line, Tumor , Chitosan , Contrast Media/pharmacokinetics , Gadolinium/pharmacokinetics , Gadolinium DTPA , Histiocytoma, Malignant Fibrous/metabolism , Humans , Metal Nanoparticles , Phantoms, Imaging
5.
Methods Inf Med ; 46(2): 147-50, 2007.
Article in English | MEDLINE | ID: mdl-17347745

ABSTRACT

OBJECTIVES: Multineuronal spike trains must be efficiently decoded in order to utilize them for controlling artificial limbs and organs. Here we evaluated the efficiency of pooling (averaging) and combining (vectorizing) activities of multiple neurons for decoding neuronal information. METHODS: Multineuronal activities in the monkey inferior temporal (IT) cortex were obtained by classifying spikes of constituent neurons from multichannel data recorded with a multisite microelectrode. We compared pooling and combining procedures for the amount of visual information transferred by neurons, and for the success rate of stimulus estimation based on neuronal activities in each trial. RESULTS: Both pooling and combining activities of multiple neurons increased the amount of information and the success rate with the number of neurons. However, the degree of improvement obtained by increasing the number of neurons was higher when combining activities as opposed to pooling them. CONCLUSION: Combining the activities of multiple neurons is more efficient than pooling them for obtaining a precise interpretation of neuronal signals.


Subject(s)
Biomedical Engineering , Electrodes, Implanted , Information Theory , Neurons , Prostheses and Implants , Signal Processing, Computer-Assisted , Animals , Haplorhini , Statistics as Topic , Time , Vision, Ocular/physiology
6.
Neuroscience ; 137(2): 401-12, 2006.
Article in English | MEDLINE | ID: mdl-16289830

ABSTRACT

Laminar organization is a fundamental cytoarchitecture in mammalian CNS and a striking feature of the neocortex. ER81, a transcription factor, has recently been utilized as a marker of cells in the layer 5 of the neocortex. We further pursued the distribution of ER81 to investigate the identity of the ER81-expressing cells in the brain. Er81 transcript was expressed in a subset of pyramidal cells that were scattered throughout the entire width of layer 5. In the rat cortex, Er81 transcripts were first detected in the ventricular zone at E15, remained expressed in putative prospective layer 5 neurons during infant and juvenile stages. The ER81-expressing subpopulation in adult layer 5 neurons did not segregate with the phenotypes of the projection targets. By retrograde labeling combined with immunohistochemistry or reverse transcription-polymerase chain reaction analysis, we found ER81 expression in nearly all of the layer 5 neurons projecting to the spinal cord or to the superior colliculus, while in only one-third of the layer 5 neurons projecting to the contralateral cortex. Er81 was also detected in layer 5 neurons in a P2 Japanese macaque monkey but not in adult monkey cortices. These findings suggest that a neuron class defined by a molecular criterion does not necessarily segregate with that defined by an anatomical criterion, that ER81 is involved in cell differentiation of a subset of layer 5 projection neurons and that this mechanism is conserved among rodents and primates.


Subject(s)
DNA-Binding Proteins/metabolism , Efferent Pathways/embryology , Efferent Pathways/growth & development , Neocortex/embryology , Neocortex/growth & development , Neurons/metabolism , Transcription Factors/metabolism , Aging/physiology , Animals , Animals, Newborn , Base Sequence , Cell Differentiation/physiology , Conserved Sequence/genetics , Corpus Callosum/cytology , Corpus Callosum/embryology , Corpus Callosum/growth & development , DNA-Binding Proteins/genetics , Efferent Pathways/cytology , Functional Laterality/physiology , Macaca fascicularis , Mice , Mice, Inbred C3H , Mice, Inbred C57BL , Mice, Inbred ICR , Molecular Sequence Data , Neocortex/cytology , Neurons/classification , Neurons/cytology , Pyramidal Cells/cytology , Pyramidal Cells/metabolism , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Rats, Wistar , Species Specificity , Spinal Cord/cytology , Spinal Cord/embryology , Spinal Cord/growth & development , Superior Colliculi/cytology , Superior Colliculi/embryology , Superior Colliculi/growth & development , Transcription Factors/genetics
7.
Redox Rep ; 10(2): 96-102, 2005.
Article in English | MEDLINE | ID: mdl-15949130

ABSTRACT

Garlic extract significantly inhibited the oxidation of methyl linoleate in homogeneous acetonitrile solution, whereas the antioxidant effect of allicin-free garlic extract, prepared by removing allicin by prepared by removing allicin by preparative HPLC, was much lower than that of the garlic extract. These results suggest that the antioxidant properties are mostly attributed to the presence of allicin in the garlic extract. Allicin a major component of the thiosulfinates in garlic extract, was found to be effective for inhibiting methyl linoleate oxidation, but its efficiency was less than that of alpha-tocopherol. Next, the reactivity of allicin toward the peroxyl radical, which is a chain-propagating species, was investigated by direct ESR detection. The addition allicin to 2,2'-azobis(2,4-dimethylvaleronitrile)-peroxyl radical solution caused the signal intensity of the peroxyl radical to dose-dependently decrease, indicating that allicin is capable of scavenging the the peroxyl radical and acting as an antioxidant. Finally, we studied the structure-anioxidant activity relationship for thiosulfinates and suggested that the combination of the allyl group (-CH2CH=CH2) and the -S(O)S- group is necessary for the antioxidant action of thiosulfinates in the garlic extract. In addition, one of the two possible combinations, -S(O)S-CH2CH=CH2, was found to make a much larger contribution to the antioxidant activity of the thiosulfinates than the other, CH2=CH-CH2-S(O)S-.


Subject(s)
Antioxidants/pharmacology , Garlic/metabolism , Plant Extracts/pharmacology , Plants, Medicinal/metabolism , Thiosulfates/chemistry , Acetonitriles/chemistry , Antioxidants/chemistry , Chromatography, High Pressure Liquid , Disulfides , Dose-Response Relationship, Drug , Electron Spin Resonance Spectroscopy , Linoleic Acids/pharmacology , Models, Chemical , Pharmaceutical Preparations , Solvents , Sulfinic Acids/chemistry , Temperature
8.
Pediatr Cardiol ; 25(4): 421-3, 2004.
Article in English | MEDLINE | ID: mdl-15493070

ABSTRACT

Congenital aneurysms of the thoracic venous system are rare. In particular, innominate venous aneurysms are extremely rare. We describe a 16-year-old girl whose chest x-ray suggested a mediastinal tumor. Three-dimensional contrast-enhancement magnetic resonance venography showed a giant sacciform aneurysm of the left innominate vein and dilatation of the right innominate vein. The patient was asymptomatic, and there were no significant physical findings. Therefore, the patient is being followed without surgical treatment.


Subject(s)
Aneurysm/congenital , Brachiocephalic Veins/abnormalities , Adolescent , Aneurysm/diagnosis , Aneurysm/surgery , Brachiocephalic Veins/surgery , Contrast Media , Diagnosis, Differential , Echocardiography , Female , Humans , Imaging, Three-Dimensional , Magnetic Resonance Imaging , Mediastinal Neoplasms/congenital , Mediastinal Neoplasms/diagnosis , Mediastinal Neoplasms/surgery , Phlebography , Soft Tissue Neoplasms/diagnosis
9.
Eur Respir J ; 22(1): 35-42, 2003 Jul.
Article in English | MEDLINE | ID: mdl-12882448

ABSTRACT

Leukotriene (LT)C4, a potent chemical mediator in bronchial asthma, is metabolised to the less active LTE4 via LTD4 in two consecutive reactions catalysed by enzymes of the glutamyl transpeptidase and dipeptidase families. The activities of these catabolic enzymes may be influenced by glucocorticosteroids. This study was conducted to examine whether this inactivation of LTC4 is affected by dexamethasone (DEX) in transformed human bronchial epithelial cells and normal human bronchial epithelial cells. After incubation with DEX for 0-5 days, cells were resuspended in the presence of exogenous LTC4, and conversion of LTC4 to LTE4 was measured using high-performance liquid chromatography. Gamma-glutamyl transpeptidase (GGT) and GGT-related enzyme (GGTRE) messenger ribonucleic acid (mRNA) expression were examined using reverse transcriptase-polymerase chain reaction analysis, and GGT activity by enzyme assay. Conversion to LTE4 was accelerated by DEX pretreatment. GGTRE but not GGT mRNA expression was enhanced after incubation with DEX. The results indicate that dexamethasone transcriptionally upregulates the activity of gamma-glutamyl transpeptidase-related enzyme in human bronchial epithelial cells, which accelerates inactivation of leukotriene C4 via conversion to leukotriene E4. This is a novel mechanism of glucocorticosteroids in human bronchial epithelial cells.


Subject(s)
Anti-Asthmatic Agents/pharmacology , Bronchi/cytology , Dexamethasone/pharmacology , Glucocorticoids/pharmacology , Leukotriene C4/metabolism , Analysis of Variance , Cell Line, Transformed , Chromatography, High Pressure Liquid , Humans , RNA, Messenger/biosynthesis , Reverse Transcriptase Polymerase Chain Reaction , gamma-Glutamyltransferase/biosynthesis
11.
Eur Radiol ; 12(8): 2087-90, 2002 Aug.
Article in English | MEDLINE | ID: mdl-12136328

ABSTRACT

The authors present the case of a newborn girl with extreme fenestration of the basilar artery. This anomaly was found incidentally during MR imaging study for cleft palate and nasopharyngeal teratoma. Magnetic resonance angiography showed a totally duplicated basilar artery with connections at the proximal and distal ends of the artery, suggesting an extreme fenestration. Duplicated pituitary gland was also found on MR imaging.


Subject(s)
Abnormalities, Multiple/diagnosis , Basilar Artery/abnormalities , Cleft Palate/diagnosis , Nasopharyngeal Neoplasms/diagnosis , Pituitary Gland/abnormalities , Teratoma/diagnosis , Cleft Palate/complications , Female , Humans , Infant, Newborn , Magnetic Resonance Imaging , Nasopharyngeal Neoplasms/complications , Teratoma/complications
12.
J Dent Res ; 80(10): 1880-3, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11706945

ABSTRACT

UNLABELLED: For orthodontic tooth movement, remodeling of the alveolar bone is maintained by a repeated process of bone resorption and new bone formation, controlled, respectively, by osteoclasts and osteoblasts. Recently, we have found that recombinant human vascular endothelial growth factor (rhVEGF) acts as a macrophage colony-stimulating factor in osteoclast induction in osteopetrotic (op/op) mice. The purpose of this study was to investigate whether rhVEGF stimulates osteoclast differentiation during experimental tooth movement. Purified rhVEGF was injected once into the buccal gingival groove around the incisors. An experimental appliance with a helical loop was bonded onto the upper incisors, and an initial force of 1.0 g was applied for three days. The number of osteoclasts appearing in the periodontal ligament space on the pressure side of the alveolar bone was increased markedly. These results suggest that local administration of rhVEGF enhances the number of osteoclasts, and may increase the rate of orthodontic tooth movement. ABBREVIATIONS: recombinant human vascular endothelial growth factor (rhVEGF), macrophage colony-stimulating factor (M-CSF), osteopetrotic mice (op/op mice),fms-like tyrosine kinase (Flt-1), periodontal ligament (PDL), phosphate-buffered saline (PBS), tartrate-resistant acid phosphatase (TRAP), and analysis of variance (ANOVA).


Subject(s)
Endothelial Growth Factors/pharmacology , Lymphokines/pharmacology , Osteoclasts/drug effects , Protein Isoforms/pharmacology , Tooth Movement Techniques , Acid Phosphatase/analysis , Alveolar Process/cytology , Alveolar Process/drug effects , Analysis of Variance , Animals , Biomarkers/analysis , Bone Remodeling/drug effects , Bone Resorption/physiopathology , Cell Differentiation/drug effects , Cell Nucleus/ultrastructure , Humans , Isoenzymes/analysis , Macrophage Colony-Stimulating Factor/pharmacology , Mice , Mice, Inbred C57BL , Mice, Inbred Strains , Models, Animal , Orthodontic Appliances , Osteoblasts/drug effects , Osteogenesis/drug effects , Periodontal Ligament/cytology , Periodontal Ligament/drug effects , Recombinant Proteins , Statistics as Topic , Stress, Mechanical , Tartrate-Resistant Acid Phosphatase , Tooth Movement Techniques/instrumentation , Vascular Endothelial Growth Factor A , Vascular Endothelial Growth Factors
13.
Proc Natl Acad Sci U S A ; 98(22): 12340-1, 2001 Oct 23.
Article in English | MEDLINE | ID: mdl-11606737

ABSTRACT

Recent studies of visual perception have begun to reveal the connection between neuronal activity in the brain and conscious visual experience. Transcranial magnetic stimulation of the human occipital lobe disrupts the normal perception of objects in ways suggesting that important aspects of visual perception are based on activity in early visual cortical areas. Recordings made with microelectrodes in animals suggest that the perception of the lightness and depth of visual surfaces develops through computations performed across multiple brain areas. Activity in earlier areas is more tightly correlated with the physical properties of objects whereas neurons in later areas respond in a manner more similar to visual perception.


Subject(s)
Brain/physiology , Neurons/physiology , Visual Perception , Humans
15.
Br J Nutr ; 86(2): 145-9, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11502226

ABSTRACT

The regulation of intracellular ascorbic acid (AsA) levels may be under the control of an AsA-specific membrane transporter. The present study investigates AsA uptake and expression of Na-dependent vitamin C transporter (SVCT) mRNA in the mouse osteoblastic cell line, MC3T3-E1. Among eight compounds tested, dexamethasone (Dex) all-trans retinoic acid, transforming growth factor beta, prostaglandin E2 and transferrin significantly and respectively) stimulated the update of AsA into MC3T3-E1 cells. Among these five, Dex was the most active, inducing mSVCT2 mRNA and the uptake of AsA in a time- and concentration-dependant manner. Dex did not induce mSVCT1 mRNA. These results suggest that the Dex-induced stimulation of AsA incorporation into osteoblastic cells is mediated by the induction of mSVCT2. Since Dex reduced alkaline phosphatase activity in MC3T3-E1 cells in our culture conditions, Dex-induced stimulation of AsA incorporation might not be the result of differentiation. Hormone-regulated changes of SVCT expression may have an important role in cell functions.


Subject(s)
Ascorbic Acid/metabolism , Carrier Proteins/genetics , Dexamethasone/pharmacology , Glucocorticoids/pharmacology , Organic Anion Transporters, Sodium-Dependent , Osteoblasts/drug effects , RNA, Messenger/analysis , Symporters , Alkaline Phosphatase/metabolism , Animals , Dose-Response Relationship, Drug , Mice , Osteoblasts/metabolism , Sodium-Coupled Vitamin C Transporters , Stimulation, Chemical , Tumor Cells, Cultured/drug effects
16.
Spine (Phila Pa 1976) ; 26(15): 1729-32, 2001 Aug 01.
Article in English | MEDLINE | ID: mdl-11474363

ABSTRACT

STUDY DESIGN: A case of multicentric osteosarcoma presenting with sacral radiculopathy is reported. OBJECTIVE: To present unusual clinical and radiologic findings of multicentric osteosarcoma. SUMMARY OF BACKGROUND DATA: Multicentric osteosarcoma is a rare variant of osteosarcoma. To the authors' knowledge, no cases of multicentric osteosarcoma presenting as sacral radiculopathy have been reported previously. METHODS: A 14-year-old boy had a large sacral tumor extending into the spinal canal, which was found to account for the initial symptoms, which mimicked those of herniated nucleus pulposus. At diagnosis, a bone survey showed multiple foci of osteosarcoma in the long bones. RESULTS: The patient was treated with chemotherapy, but died of the disease 8 months after the initial presentation. CONCLUSION: Multicentric osteosarcoma should be considered in the differential diagnosis for a pediatric patient with low back pain and sciatica.


Subject(s)
Bone Neoplasms/complications , Osteosarcoma/complications , Radiculopathy/etiology , Sacrum/pathology , Adolescent , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Bone Neoplasms/diagnosis , Bone Neoplasms/drug therapy , Fatal Outcome , Humans , Magnetic Resonance Imaging , Male , Osteosarcoma/diagnosis , Osteosarcoma/drug therapy , Osteosarcoma/secondary , Radiculopathy/diagnosis , Radiography , Radionuclide Imaging , Sacrum/diagnostic imaging
17.
Acta Crystallogr D Biol Crystallogr ; 57(Pt 8): 1174-6, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11468410

ABSTRACT

MRP14 is a protein that is specifically expressed in myeloid and epithelial cells during the stages of acute or chronic inflammatory states such as rheumatoid arthritis or sarcoidosis. MRP14 has EF-hand motifs as Ca(2+)-binding sites and belongs to the S100 family of proteins. This paper deals with the sample preparation (cloning, overexpression and purification), crystallization and preliminary crystallographic analysis of recombinant human MRP14. Crystals of MRP14 were obtained by the hanging-drop vapour-diffusion method. MRP14 crystals belong to space group P2(1), with unit-cell parameters a = 57.59, b = 178.44, c = 61.23 A, beta = 113.17 degrees, and diffract to 2.1 A resolution.


Subject(s)
Antigens, Differentiation/chemistry , S100 Proteins/chemistry , Amino Acid Sequence , Antigens, Differentiation/biosynthesis , Antigens, Differentiation/isolation & purification , Calcium/metabolism , Calgranulin B , Cloning, Molecular , Crystallization , Crystallography, X-Ray , Humans , Molecular Sequence Data , S100 Proteins/biosynthesis , S100 Proteins/isolation & purification , Sequence Homology, Amino Acid
18.
Neurosci Res ; 39(4): 469-72, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11274746

ABSTRACT

To examine whether visual attention to global and local features of visual stimuli modulates neural activity in the monkey visual cortex, we applied positron emission tomography techniques to monkeys while they were discriminating either global or local features of visual stimuli. The posterior inferior temporal cortex was more activated in discriminating global features than in discriminating local ones, whereas the anterior inferior temporal cortex was more activated in discriminating local features than in discriminating global ones. The results suggest that a functional difference exists in terms of processing of global and local features within the inferior temporal cortex.


Subject(s)
Action Potentials/physiology , Attention/physiology , Neurons/physiology , Temporal Lobe/physiology , Visual Cortex/physiology , Visual Perception/physiology , Animals , Brain Mapping , Functional Laterality/physiology , Macaca , Neurons/cytology , Photic Stimulation , Psychomotor Performance/physiology , Temporal Lobe/cytology , Tomography, Emission-Computed , Visual Cortex/cytology , Visual Pathways/cytology , Visual Pathways/physiology
19.
J Neurophysiol ; 85(2): 735-44, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11160508

ABSTRACT

Neurons in the monkey inferior temporal cortex (IT) have been shown to respond to shapes defined by luminance, texture, or motion. In the present study, we determined whether IT neurons respond to shapes defined solely by binocular disparity, and if so, whether signals of disparity and other visual cues to define shape converge on single IT neurons. We recorded extracellular activity from IT neurons while monkeys performed a fixation task. Among the neurons that responded to at least one of eight random-dot stereograms (RDSs) containing different disparity-defined shapes, 21% varied their responses to different RDSs. Responses of most of the neurons were positively correlated between two sets of RDSs, which consisted of different dot patterns but defined the same set of eight shapes, whereas responses to RDSs and their monocular images were not correlated. This indicates that the response modulation for the eight RDSs reflects selectivity for shapes (or their component contours) defined by disparity, although responses were also affected by dot patterns per se. Among the neurons that showed selectivity for shapes defined by luminance or disparity, 44% were activated by both cues. Responses of these neurons to luminance-defined shapes and those to disparity-defined shapes were often positively correlated to each other. Furthermore the stimulus rank, which was determined by the magnitude of responses to shapes, generally matched between these cues. The same held true between disparity and texture cues. The results suggest that the signals of disparity, luminance, and texture cues to define the shapes converge on a population of single IT neurons to produce the selectivity for shapes.


Subject(s)
Form Perception/physiology , Temporal Lobe/physiology , Animals , Contrast Sensitivity , Convergence, Ocular/physiology , Cues , Eye Movements/physiology , Fixation, Ocular/physiology , Lighting , Macaca , Male , Neurons/physiology , Photic Stimulation/methods , Temporal Lobe/cytology , Vision, Monocular/physiology
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