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E Iwai

Publications and source records attributed to E Iwai.

At least 37 records · Page 2Linked to original sources

[EGF receptor and effects of EGF on growth and tumor marker secretion in uterine cervical cancer cells].

Effects of EGF on proliferation and tumor marker secretion of cervical cancer cells are reported together with the characteristics of EGF receptors on the cells. TA-4 producing cell line (OMC-1) originating from cervical squamous cell carcinoma and CA-125 producing cell line (OMC-4) originating from cervical adenocarcinoma, were used. Scatchard plot of EGF binding to OMC-1 indicated a single class of binding sites with a dissociation constant (Kd) of 360pM, whereas that of OMC-4 was curvilinear suggesting two classes of binding sites with a Kd of 170pM and 510pM. The theoretical maximum number of binding sites of OMC-1 and OMC-4 was 2.4 X 10(4) and 1.6 X 10(5), respectively. Effects of EGF on growth were studied by monitoring cell number and the incorporation of 3H-thymidine into the DNA of the cells. OMC-1 was stimulated by EGF at low concentrations (0.01-0.1nM) and inhibited at higher concentrations. OMC-4 was not stimulated by EGF. The TA-4 secretion of OMC-1 was slightly stimulated by EGF at low concentrations (0.01-1nM) and significantly stimulated at high concentration (10nM). The CA-125 secretion of OMC-4 was not stimulated by EGF. These results suggest that there are some differences between cervical squamous cell carcinoma and adenocarcinoma in the mechanisms of regulation of proliferation and tumor marker secretion by EGF.

Adenocarcinoma↗

Amygdalar connections with middle and inferior temporal gyri of the monkey.

The origins and terminations of the amygdalar connections with middle (ITm) and inferior temporal (ITi) gyri of inferotemporal cortex (area TE) were studied in Japanese monkeys by the horseradish peroxidase method. The ITm gyrus received a major projection from the lateral basal nucleus and a minor one from the accessory basal nucleus of the amygdala, whereas it sent a major projection to the lateral nucleus and a minor one to the lateral basal nucleus. The ITi gyrus had only minor amygdalar projections from the medial basal nucleus and to the medial basal and lateral nuclei.

Amygdala↗

Amygdalofugal and amygdalopetal connections with modality-specific visual cortical areas in macaques (Macaca fuscata, M. mulatta, and M. fascicularis).

The origins and terminations of the amygdaloid connections with the modality-specific visual cortical areas TEa (anterior TE area), TEp (posterior TE area), TEO, V4, V2, MST (medial superior temporal visual area), MT (middle temporal visual area), and V1 were studied in macaques. These were compared with the amygdaloid connections of a vision-related polysensory area TG by making cortical injections of horseradish peroxidase (HRP) and incubating the sections with tetramethylbenzidine (TMB) as the chromogen. Both areas TEa and TEp receive a major projection from the lateral basal nucleus and a minor one from the accessory basal nucleus of the amygdaloid complex, whereas these areas send a major projection to the lateral nucleus and a minor one to the lateral basal nucleus. Areas TEO, V4, V2, MST, MT, and V1 receive projections only from the lateral basal nucleus; none of them project to any amygdaloid nucleus. Thus, the amygdalofugal projections are more widespread and more complex than the amygdalopetal projections. These findings indicate that the connections between the amygdaloid nuclei and the visual areas are generally nonreciprocal and underlie the importance of a feedback mechanism from the amygdala to the visual cortical areas in visual information processing. There appears to be a caudorostral (occipitotemporal) gradient in the distribution and density of the amygdaloid projections, which become progressively more widespread and heavier among the progressively more rostral visual areas (from area V1 to area TEa). The amygdaloid connections with area TG are distinctly different from the connections with the visual areas. Area TG is reciprocally connected mainly with the periamygdaloid cortex, and with the lateral, accessory basal, and medial basal nuclei of the amygdala as well.

Amygdala↗

Inferotemporal neurons of the monkey responsive to auditory signal.

Responsiveness of single inferotemporal (IT) neurons to a tone as a start or warning signal in each test trial was investigated in monkeys performing visual discrimination of 4 patterns. It was found that the same IT neurons were responsive to both auditory signal and visual discriminanda with different response characteristics from each other. The activity of IT neurons for the auditory signal in the visual discrimination paradigm reflects an engagement process in attention to the visual discriminanda.

Animals↗

Acquisition of discrimination learning of patterns identical in configuration in macaques (Macaca mulatta and M. fuscata).

The acquisition of discrimination of five pairs of pattern cues in a Wisconsin General Testing Apparatus by 223 naive macaque monkeys was compared. The pairs of discriminanda were identical in configuration but varied slightly in either the size of the cue or the size of the background plaque; thus, the degree of separation of the cue from the fringe of the plaque, the response site, was slightly different for each pair of discriminanda. These small differences in cue-response separation had marked effects on the rate of acquisition of the discriminations. Even an increment of separation as small as 0.5 cm resulted in a remarkable retardation of the acquisition. This retardation was due entirely to prolonged performance at the chance level, and not to a slow rate of improvement from the chance to a criterion level. The finding indicates that the difficulty in the acquisition learning on pattern tasks depends largely on the difficulty of attending to the pattern cues at small cue-response separations.

Animals↗

Effect of small cue-response separation on pattern discrimination in macaques (Macaca fuscata and M. mulatta).

In order to elucidate the nature of the effect of small cue-response separations on pattern discriminations by monkeys, three studies were performed. When training on a pattern discrimination with a cue-response separation was discontinued during performance at the chance level, there was no saving on the rate of learning a second task (with identical cues but a different cue-response separation) relative to the performance of naive control animals. By contrast, when training was discontinued at a performance level a little better than chance, there was significant saving on learning a second task. After learning the second task, a third task with new pattern cues was learned, with marked saving on the duration of performance at the chance level. The results indicate that during the initial stage of performance at the chance level, monkeys do not attend to cues if there is even a small separation between the cue and the response site.

Animals↗

Analysis of local and wide-field movements in the superior temporal visual areas of the macaque monkey.

The middle temporal (MT) and medial superior temporal (MST) areas of the macaque cortex have many cells that respond to straight movements in the frontoparallel plane with directional selectivity (D cells). We examined their responses to movements of a bar, of a wide dot pattern, and to combined movements of the two in anesthetized and immobilized animals. D cells in MT showed a wide variety in the strength of the inhibitory field surrounding the excitatory center field. Responses of SI+-type cells to a bar moving across the excitatory field were suppressed when a wide dot pattern moved over the surround field in the same direction and at the same speed as the bar. Inhibition was selective to the direction and speed of the surround movement, and the effective area for inhibition occupied a wide area, which expanded in all radial directions. Responses of SI- -type cells to a center bar movement were changed little by a conjoint movement over the surround field. Consequently, SI- -type cells responded to wide-field movement as well as to stimuli confined within the excitatory field. Although D cells in MST commonly had large excitatory fields, a proportion of them (Figure type) responded to bar movement much more strongly than to wide-field movement. Their responses to a bar movement were suppressed direction-selectively by a conjoint movement of a wide dot-pattern background. The effective area for inhibition coexisted with the excitatory field in these cells. MST cells of the Nonselective type responded comparably well to the two stimuli, and those of the Field type responded much more strongly to wide-field movement than to bar movement. It is thus suggested that MT cells of the SI+ type and MST cells of the Figure type can detect a difference between movements of an object and its wide background, whereas MST cells of the Field type can detect a conjoint movement of a wide field, neglecting the movements of a single object.

Acoustic Stimulation↗

Integration of direction signals of image motion in the superior temporal sulcus of the macaque monkey.

Using anesthetized and paralyzed monkeys, we have studied the visual response properties of neurons in the cortical area surrounding the middle temporal area (MT) in the superior temporal sulcus (STS). Systematic electrode penetrations revealed that there is a functionally distinct region where three classes of directionally selective cells with large receptive fields cluster. This region is anteriorly adjoined to the dorsal two-thirds of MT, has a width of 4-5 mm mediolaterally, and therefore may correspond to the dorsal part of the medial superior temporal area (MST), which was previously defined as a MT-recipient zone. One class of cells responded to a straight movement of patterns in the frontoparallel plane with directional selectivity (D cells: 217/422, 51.4%). The second class of cells selectively responded to an expanding or contracting size change of patterns (S cells: 66/422, 15.7%). These cells responded neither to a change in width of a slit of any orientation or any length, nor to a change in brightness. The third class of cells responded only to a rotation of patterns in one direction (R cells: 58/422, 13.7%). A majority of these cells (41/58) responded to the clockwise or counterclockwise rotation of patterns in the frontoparallel plane (Rf cells), while the rest responded to a rotation of patterns in depth (Rd cells). We will suggest that these cells acquire the ability to discover whole events of visual motion--i.e., unidirectional straight movement, size change (radial movement), and rotation--by integrating elemental motion information extracted by MT cells. The receptive fields of D, S, and Rf cells can be constructed by converging signals of MT cells, the preferred directions of which are arranged in parallel (D cells), radially (S cells), and circularly (Rf cells). The receptive fields of Rd cells can be constructed, in turn, by the convergence of signals of S cells.

Animals↗

Laminar origin of direct projection from cortex area V1 to V4 in the rhesus monkey.

Direct projection from cortex area V1 to V4 in the rhesus monkey was demonstrated by means of retrograde axonal transport of wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP). This projection originated at the layers 2 and 3 of the only representation area of central visual field (0-6 degrees) in V1 and terminated at the central representation of V4, whereas there was no projection between the extracentral representations of V1 and V4. Correlation of the present finding with the previous findings suggests that this projection is predominantly involved in the system of color information processing.

Animals↗

Neuropsychological basis of pattern vision in macaque monkeys.

The central mechanisms of underlying pattern vision in macaques (rhesus and Japanese monkeys) were investigated behaviorally and electrophysiologically. A series of studies indicated that there are two major processes underlying pattern vision. One of two processes is the process of attending selectively to pattern cues at background, with which inferior parietal cortex is concerned predominantly. The other is the process of pattern perception and cognition, in which inferotemporal cortex is involved closely.

Animals↗

Further evidence on elevated discrimination limens for reduced patterns in monkeys with inferotemporal lesions.

An attempt was made to elucidate the nature and neural basis of the elevated discrimination limen for visual stimuli of reduced sizes that had been discovered earlier in monkeys with inferotemporal lesions. Although anterior inferotemporal damage was found to have only negligible effect, both total inferotemporal and posterior inferotemporal lesions yielded markedly elevated limens for reduced pattern stimuli but not for reduced colour stimuli. The impaired animals could be trained to discriminate reduced patterns that were below their original discrimination limen, but this required many more trials than were needed for postoperative relearning of the initial pair; normal animals, by contrast, showed perfect transfer from the standard to the smallest pair. The findings suggest that the increased threshold for reduced patterns in monkeys with inferotemporal lesion is attributable not to a visual acuity disorder but to an impairment of pattern perception resulting mainly from damage to posterior inferotemporal cortex.

Animals↗

Direct projection from the dorsal lateral geniculate nucleus to the prestriate cortex in macaque monkeys.

The enzyme horseradish peroxidase (HRP) was separately injected into striate, prestriate, inferotemporal, and parietal cortices in 19 macaque monkeys, and the lateral geniculate nucleus (LGN) was examined for retrograde transport. Labeled LGN cells were identified only in the animals, with HRP injections into the striate and prestriate cortex. Following injections into either of these regions, labeled cells were found in both parvocellular and magnocellular regions of the ipsilateral LGN only, in keeping with the topographic relation of HRP injection sites in the cortex to labeled areas in the LGN. It was also found that (1) labeled LGN cells were less numerous in both laminar and interlaminar zones following HRP injection into the prestriate cortex, whereas following HRP injection into the striate cortex labeled cells were found almost exclusively in the laminae, and localized to a wedge-shaped region; (2) following HRP injection into the prestriate cortex, the mean sizes of the labeled parvocellular and magnocellular cells, estimated in projected diameter, were almost the same, these means being significantly larger than the mean size of labeled parvocellular cells and much smaller than that of labeled magnocellular cells following HRP injection into the striate cortex; (3) the shapes of the labeled LGN cells following HRP injection into the prestriate cortex were ovoid, fusiform, or triangular (or multipolar), whereas those following HRP injection into the striate cortex were uniformly ovoid or round. The above findings following HRP injections into the prestriate cortex in normal monkeys were confirmed by HRP injections into the prestriate cortex of monkeys whose striate cortex had been removed several months prior to the injection; labeled cells were found in confines of areas of retrograde degeneration in the LGN and their labeling pattern was the same as that in intact animals. It was concluded that in macaque monkeys, just as in the cat, a geniculoprestriate projection system exists; it was suggested that there are two parallel system of visual information processing from the LGN to the prestriate cortex, a direct one and in indirect one through the striate cortex.

Animals↗

The locus of the posterior subdivision of the inferotemporal visual learning area in the monkey.

In an attempt to define the posterior subdivision of the inferotemporal visual learning area more precisely than before, pattern discrimination retention, serial object discrimination learning and concurrent object discrimination learning were tested in 16 monkeys with lesions in one of four different cytoarchitectural areas; TEO, OA, OB and OC, and in five unoperated monkeys. Marked impairment was found only in pattern discrimination retention and only in the monkeys with lesions of area TEO. It was concluded that the posterior limit of the inferotemporal visual learning area is at the ascending limb of the inferior occipital sulcus, and that the posterior subdivision thus comprises the single anatomical area TEO and does not extend into areas OA and OB.

Animals↗

Responsiveness of inferotemporal single units to visual pattern stimuli in monkeys performing discrimination.

Four monkeys were trained to choose two rewarded stimuli from four two-dimensional patterns presented successively, and the responsiveness of single units to these patterns was investigated. Eighty-three of 214 units (39%) recorded from the dorsolateral portion of the inferotemporal cortex were responsive; nearly half responded to all four patterns, irrespective of pattern shape and of whether the stimuli were rewarded or not. A few units were responsive to only one of the patterns, regardless of size, color, or luminance, and unresponsiveness to components of the response-eliciting patterns was indicated in some of these units. The activity of most units response to two or three patterns was dependent on pattern shapes rather than the learnt meaning of the patterns.

Animals↗

Elevation of visual pattern discrimination limen in monkeys with total removal of inferotemporal cortex.

Attempts were made to test the validity of the general view that inferotemporal lesions in monkeys do not result in a visual acuity disorder. It was found in the first experiment that monkeys with total removal of the inferotemporal visual area (TIT monkeys) showed a significant elevation of the discrimination limen for visual patterns of reduced sizes even when compared to monkeys with removal of lateral striate cortex (LS monkeys); yet in a food-morsel (raisin) detection test the TIT monkeys performed as well as normal monkeys, although the LS monkeys showed significant deficits. A second experiment was conducted, in which the same subjects were tested with the same patterns as in the first experiment but with the stimulus background changed from the square used earlier to an enlarged disc. While both normal and LS monkeys performed this task easily, the TIT monkeys could not learn the discrimination within the training limit of 1,200 trials. The results suggest that such a marked elevation of the discrimination limen in the TIT monkeys as found in the first experiment is not attributable to a visual acuity disorder, but is explained as due to an impairment of the pattern perception mechanism.

Animals↗

Visual discrimination in monkey with removal of inferotemporal cortex.

The monkey with removal of the inferotemporal cortex (IT monkey) showed a marked impairment of discrimination between a pair of visual pattern stimuli, which consisted of different patterns on the identical background [corrected] plaques. The present study showed that an IT monkey, unlike an unoperated normal monkey, performed discrimination with utilizing a partial cue within the whole configuration of pattern stimuli. In contrast to a general concept, the present finding appears to raise a question as to whether the IT monkey can perceive or identify visual pattern.

Animals↗