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Kato MC, Hikosaka K, Hirose T. Photoinactivation and recovery of photosystem II in Chenopodium album leaves grown at different levels of irradiance and nitrogen availability. FUNCTIONAL PLANT BIOLOGY : FPB 2002; 29:787-795. [PMID: 32689526 DOI: 10.1071/pp01162] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Involvement of photosynthetic capacity and D1 protein turnover in the susceptibility of photosystem II (PSII) to photoinhibition was investigated in leaves of Chenopodium album L. grown at different combinations of irradiance and nitrogen availability: low light and high nitrogen (LL-HN); high light and low nitrogen (HL-LN); and high light and high nitrogen (HL-HN). To test the importance of photosynthetic capacity in the susceptibility to photoinhibition, we adjusted growth conditions so that HL-HN plants had the highest photosynthetic capacity, while that of LL-HN and HL-LN plants was lower but similar to each other. Photoinhibition refers here to net inactivation of PSII determined by the balance between gross inactivation (photoinactivation) and concurrent recovery of PSII via D1 protein turnover. Leaves were illuminated both in the presence and absence of lincomycin, an inhibitor of chloroplast-encoded protein synthesis. Susceptibility to photoinhibition was much higher in plants grown in low light (LL-HN) than those grown in high light (HL-HN and HL-LN). Susceptibility to photoinhibition was similar in HL-LN and HL-HN plants, suggesting that higher photosynthetic energy consumption alone did not mitigate photoinhibition. Experiments with and without lincomycin showed that high-light-grown plants had a lower rate of photoinactivation and a higher rate of concurrent recovery, and that these rates were not influenced by nitrogen availability. These results indicate that turnover of D1 protein plays a crucial role in photoprotection in high-light-grown plants, irrespective of nitrogen availability. For low-nitrogen-grown plants, higher light energy dissipation by other mechanisms may have compensated for lower energy utilization by photosynthesis.
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102
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Zhao S, Kuge Y, Tsukamoto E, Mochizuki T, Kato T, Hikosaka K, Nakada K, Hosokawa M, Kohanawa M, Tamaki N. Fluorodeoxyglucose uptake and glucose transporter expression in experimental inflammatory lesions and malignant tumours: effects of insulin and glucose loading. Nucl Med Commun 2002; 23:545-50. [PMID: 12029209 DOI: 10.1097/00006231-200206000-00006] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The expression of glucose transporters (GLUTs) and its relationship to fluorodeoxyglucose accumulation in malignant tumours have been well investigated, while such a relation has not been studied in inflammatory lesions. The aim of the present study was to investigate the effects of insulin and glucose loading on the expression of GLUTs in inflammatory lesions and compare them with those in malignant tumours in relation to fluorodeoxyglucose accumulation. All tissue specimens used in this study were obtained in our previous study, in which rats were inoculated with allogenic hepatoma cells (KDH-8), Staphylococcus aureus, or turpentine oil into the left calf muscle and divided into three subgroups: insulin loaded, glucose loaded, and control groups. The expression of glucose transporters (GLUT-1 to GLUT-5) was investigated by immunostaining the lesions (n=5-6, for each group). In all control groups, the expression levels of GLUT-1 and GLUT-3 were significantly higher than those of GLUT-2, GLUT-4 and GLUT-5. Insulin loading did not significantly affect the expression levels of GLUT-1 and GLUT-3 in these lesions except for a significant but slight decrease in the GLUT-1 expression level in the inflammatory lesion of non-infectious origin (89% of the control value). Glucose loading significantly decreased the expression level of GLUT-1 in the inflammatory lesion of non-infectious origin (70% of the control value, P<0.01), and that of GLUT-3 in the inflammatory lesion of infectious origin (70% of the control value, P<0.05), while the expression levels of GLUT-1 and GLUT-3 in the tumour were not significantly affected. These results demonstrate the effects of insulin and glucose loading on the expression level of a molecule (GLUT proteins). The decreased GLUT-1 and GLUT-3 expression levels induced by glucose loading may partly explain the impaired FDG uptake observed in our previous study.
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Hikosaka K, Hanba YT, Hirose T, Terashima I. Photosynthetic nitrogen-use efficiency in leaves of woody and herbaceous species. Funct Ecol 2002. [DOI: 10.1046/j.1365-2435.1998.00272.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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104
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Kato MC, Hikosaka K, Hirose T. Leaf discs floated on water are different from intact leaves in photosynthesis and photoinhibition. PHOTOSYNTHESIS RESEARCH 2002; 72:65-70. [PMID: 16228535 DOI: 10.1023/a:1016097312036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Photoinhibition has been often evaluated with leaf discs floated on water or placed on wet papers to prevent desiccation. Under these conditions, there is a possibility that CO(2) diffusion is blocked by water, which may lead to reduction in photosynthetic CO(2) assimilation. Using Chenopodium album L. grown at two irradiances, photosynthesis, quantum yield of Photosystem II (DeltaF/F (m)'), non-photochemical quenching (qN), and photoinhibition were compared between detached leaves and leaf discs. In low-light-grown plants, photoinhibition was greater in leaf discs than in detached leaves, while in high-light-grown plants, there was little difference. Leaf discs showed lower rates of photosynthesis and DeltaF/F (m)', and higher qN. The DeltaF/F (m)' in leaf discs increased when leaf discs were exposed to high concentration of CO(2), suggesting that CO(2) diffusion to chloroplasts was limited in leaf discs floated on water.
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105
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Hikosaka K, Nagashima H, Harada Y, Hirose T. A simple formulation of interaction between individuals competing for light in a monospecific stand. Funct Ecol 2001. [DOI: 10.1046/j.0269-8463.2001.00557.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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106
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Watanabe M, Cromwell HC, Tremblay L, Hollerman JR, Hikosaka K, Schultz W. Behavioral reactions reflecting differential reward expectations in monkeys. Exp Brain Res 2001; 140:511-8. [PMID: 11685405 DOI: 10.1007/s002210100856] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2001] [Accepted: 06/15/2001] [Indexed: 12/01/2022]
Abstract
Learning theory emphasizes the importance of expectations in the control of instrumental action. This study investigated the variation of behavioral reactions toward different rewards as an expression of differential expectations of outcomes in primates. We employed several versions of two basic behavioral paradigms, the spatial delayed response task and the delayed reaction task. These tasks are commonly used in neurobiological studies of working memory, movement preparation, and event expectation involving the frontal cortex and basal ganglia. An initial visual instruction stimulus indicated to the animal which one of several food or liquid rewards would be delivered after each correct behavioral response, or whether or not a reward could be obtained. We measured the reaction times of the operantly conditioned arm movement necessary for obtaining the reward, and the durations of anticipatory licking prior to liquid reward delivery as a Pavlovian conditioned response. The results showed that both measures varied depending on the reward predicted by the initial instruction. Arm movements were performed with significantly shorter reaction times for foods or liquids that were more preferred by the animal than for less preferred ones. Still larger differences were observed between rewarded and unrewarded trials. An interesting effect was found in unrewarded trials, in which reaction times were significantly shorter when a highly preferred reward was delivered in the alternative rewarded trials of the same trial block as compared to a less preferred reward. Anticipatory licks preceding the reward were significantly longer when highly preferred rather than less preferred rewards, or no rewards, were predicted. These results demonstrate that behavioral reactions preceding rewards may vary depending on the predicted future reward and suggest that monkeys differentially expect particular outcomes in the presently investigated tasks.
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Mochizuki T, Tsukamoto E, Kuge Y, Kanegae K, Zhao S, Hikosaka K, Hosokawa M, Kohanawa M, Tamaki N. FDG uptake and glucose transporter subtype expressions in experimental tumor and inflammation models. J Nucl Med 2001; 42:1551-5. [PMID: 11585872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
UNLABELLED Although FDG uptake is closely related to the expression of the glucose transporter (GLUT) in malignant tumors, such a relationship has not been fully investigated in inflammatory lesions. The aim of our study was to determine the expression of GLUT subtypes in experimental inflammatory lesions and to compare the results with those in malignant tumors in relation to FDG accumulation. METHODS Rats were inoculated with a suspension of Staphylococcus aureus or allogenic hepatoma cells (KDH-8) into the left calf muscle. Five days after S. aureus inoculation (n = 9) and 14 d after KDH-8 inoculation (n = 11), [(14)C]FDG was injected intravenously and its accumulation in the infectious and tumor tissues was determined as the percentage activity of the injected dose per gram of tissue (%ID/g). The expression of glucose transporters (GLUT-1 to GLUT-5) was investigated by immunostaining the infectious tissues (n = 6) and the tumor tissues (n = 6). Immunohistochemical grading was assessed semiquantitatively by 5 observers. RESULTS The [(14)C]FDG uptake was significantly higher in the tumor lesion than in the inflammatory lesion (2.04 +/- 0.38 %ID/g vs. 0.72 +/- 0.15 %ID/g; P < 0.0001). The tumor and inflammatory tissues highly expressed GLUT-1 and GLUT-3. The GLUT-1 expression level was significantly higher in the tumor tissue than in the inflammatory tissue (P < 0.05). CONCLUSION The results based on our models showed a high FDG uptake and high GLUT-1 expression level not only in the tumor lesion but also in the inflammatory lesion. The higher GLUT-1 expression level in the tumor lesion may partially explain the higher FDG accumulation in the tumor than in the inflammatory lesion.
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Zhao S, Kuge Y, Tsukamoto E, Mochizuki T, Kato T, Hikosaka K, Hosokawa M, Kohanawa M, Tamaki N. Effects of insulin and glucose loading on FDG uptake in experimental malignant tumours and inflammatory lesions. EUROPEAN JOURNAL OF NUCLEAR MEDICINE 2001; 28:730-5. [PMID: 11440033 DOI: 10.1007/s002590100517] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Fluorine-18 2-deoxy-2-fluoro-D-glucose (FDG) accumulation in tumours has been well investigated, but much less is known regarding FDG accumulation in inflammatory lesions. In this study, we determined the effects of hypo- and hyperglycaemia on FDG uptake in inflammatory lesions of infectious and non-infectious origin and compared them with those in malignant tumours in rats, to provide a biological basis for differentiating malignant lesions from benign lesions by means of FDG-PET. Rats were inoculated with a suspension of allogenic hepatoma cells (KDH-8) or Staphylococcus aureus, or with turpentine oil into the left calf muscle. Two weeks after KDH-8 inoculation and 1 week after S. aureus and turpentine oil inoculations, the rats were divided into three subgroups: insulin-loaded (2 U/kg body weight, i.p.), glucose-loaded (1.2 g/kg body weight, p.o.) and control groups. Radioactivity in tissues was determined 1 h after i.v. injection of FDG. Intraperitoneal injection of insulin and oral administration of glucose induced hypoglycaemia and hyperglycaemia, respectively. In the control animals, tumours showed a level of FDG uptake which was 2.2 and 3.0 times higher than the levels in the inflammatory lesions induced by S. aureus and turpentine oil, respectively (P<0.0001). There was no significant difference in the level of FDG uptake between the two inflammatory lesions of infectious and non-infectious origin. Insulin loading significantly decreased the level of FDG uptake in tumours and in both types of inflammatory lesion to approximately one-half of the control values (P=0.001 in the tumour group and P<0.0001 in the two inflammatory lesion groups). In the glucose-loaded group, the level of FDG uptake in both types of inflammatory lesion decreased significantly to 50%-61% of the control value (P=0.0002 in the S. aureus group and P<0.0001 in the turpetine group), while the tumour uptake did not decrease significantly (86% of the control value) (P=NS). It is concluded that FDG uptake in both types of inflammatory lesion was significantly impaired in rats with hyperglycaemia induced by glucose loading, while tumour uptake of FDG was not significantly affected. These results indicate that glucose loading has greater effects on FDG uptake in inflammatory lesions than in tumours, providing a biological basis for differentiation of malignant lesions from benign lesions by FDG-PET in a clinical setting.
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Hikosaka K, Hirose T. Photosynthetic nitrogen-use efficiency in evergreen broad-leaved woody species coexisting in a warm-temperate forest. TREE PHYSIOLOGY 2000; 20:1249-1254. [PMID: 12651488 DOI: 10.1093/treephys/20.18.1249] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Photosynthetic nitrogen-use efficiency (PNUE, photosynthetic capacity per unit leaf nitrogen) varies among species from different habitats and correlates with several ecological characteristics such as leaf life span and leaf mass per area. We investigated eight evergreen broad-leaved woody species with different leaf life spans that coexist in a warm-temperate forest. We determined photosynthetic capacity at ambient CO(2) concentration in saturated light, nitrogen concentration, and the concentration of ribulose-1,5-bisphosphate carboxylase (RuBPCase), a key enzyme of photosynthesis and the largest sink of nitrogen in leaves. Each species showed a strong correlation between photosynthetic capacity and RuBPCase concentration, and between RuBPCase concentration and nitrogen concentration. Photosynthetic capacity of leaves decreased with increasing leaf life span, whereas PNUE did not correlate significantly with leaf life span. There was a twofold variation in PNUE among species. This relatively small variation in PNUE is consistent with the argument that species that coexist in a single habitat maintain a similar PNUE. The two components of PNUE-photosynthetic rate per unit RuBPCase and RuBPCase per unit leaf nitrogen-were not significantly correlated with other leaf characteristics such as leaf life span and leaf mass per area. We conclude that differences in PNUE are relatively small among coexisting species and that differences in absolute amounts of photosynthetic proteins lead to differences in photosynthetic productivity among species.
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Hikosaka K, Watanabe M. Delay activity of orbital and lateral prefrontal neurons of the monkey varying with different rewards. Cereb Cortex 2000; 10:263-71. [PMID: 10731221 DOI: 10.1093/cercor/10.3.263] [Citation(s) in RCA: 274] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We examined neuronal activity in the orbitofrontal cortex (OFC) in relation to reward expectancy and compared findings with those of the lateral prefrontal cortex (LPFC) in the monkey. Activity of OFC neurons was examined in a delayed reaction time task where every four trials constituted one block within which three kinds of rewards and no reward were delivered in a fixed order. More than half of OFC delay neurons were related to the expectancy of delivery or nodelivery of a reward as the response outcome, while some neurons showed nature-of-reward-specific anticipatory activity changes. These delay-related activities reflected the preference of the animal for each kind of reward and were modulated by the motivational state of the animal. LPFC neurons are reported to show nature-ofreward-specific anticipatory activity changes in a delayed response task when several different kinds of rewards are used. Such rewarddependent activity is observed in LPFC delay neurons both with and without spatially differential delay (working memory-related) activity. Although reward expectancy-related activity is commonly observed in both OFC and LPFC, it is suggested that the OFC is more concerned with motivational aspects, while the LPFC is related to both the cognitive and motivational aspects of the expectancy of response outcome.
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111
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Hikosaka K. Tolerances of responses to visual patterns in neurons of the posterior inferotemporal cortex in the macaque against changing stimulus size and orientation, and deleting patterns. Behav Brain Res 1999; 100:67-76. [PMID: 10212054 DOI: 10.1016/s0166-4328(98)00114-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neuronal activities were recorded in areas TEO and TE of the inferotemporal cortex in four hemispheres of two monkeys during the performance of a visual pattern discrimination task. Tolerances of responses to patterns against changing stimulus size and orientation, and deleting patterns halves were investigated and compared between TEO and TE neurons. Of 311 neurons tested, 80 (26%) responded to one or more patterns out of four standard patterns. Of these 80 neurons, 50 (63%) were recorded in area TEO and 30 (38%) in area TE. Neurons responsive to patterns were recorded in both areas TEO and TE, however degrees of tolerance of responses were different between TEO and TE neurons. Tolerances of TEO neurons were moderate and degrees of tolerance varied from neuron to neuron. Responses to particular patterns were dependent on stimulus size, stimulus orientation, and/or completeness of patterns. By contrast, tolerances of TE neurons were generally strong. Responses to particular patterns were not affected by changing stimulus size, changing stimulus orientation nor deleting patterns halves. These results suggest that area TEO rather than area TE is involved in detecting and processing particular visual shapes.
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112
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Hikosaka K, Sudoh S, Hirose T. Light acquisition and use by individuals competing in a dense stand of an annual herb, Xanthium canadense. Oecologia 1999; 118:388-396. [PMID: 28307283 DOI: 10.1007/s004420050740] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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113
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Hikosaka K. Representation of foveal visual fields in the ventral bank of the superior temporal sulcus in the posterior inferotemporal cortex of the macaque monkey. Behav Brain Res 1998; 96:101-13. [PMID: 9821547 DOI: 10.1016/s0166-4328(97)00202-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Using anesthetized and immobilized monkeys, this study investigated the representation of the visual field in the superior temporal sulcus in the posterior inferotemporal cortex. Of 1043 neurons in the posterior inferotemporal cortex including the sulcus and the gyrus, and surrounding areas that were tested, 540 (52%) responded to visual stimuli and their receptive fields were mapped. In the ventral bank of the superior temporal sulcus at the level corresponding to the posterior middle temporal sulcus, the foveal visual fields, which were dominant, were represented ventrally and the parafoveal visual fields dorsally. The upper and lower visual fields were represented intermingledly and no segregation between the representation of the upper and lower visual fields was seen. In the lateral convexity of the gyrus, the foveal visual fields were represented dorsally and the peripheral visual fields ventrally with the foveal visual fields being predominant. The upper visual fields were represented posteriorly, however locations and sizes of the representation of the upper and lower visual fields varied between hemispheres. The receptive field sizes of neurons in the sulcus were almost the same as those in the gyrus, and these receptive field sizes were intermediate between those of anterior inferotemporal neurons and V4 neurons. These findings suggest that the cortex in the sulcus in the posterior inferotemporal cortex is involved in the central vision, similarly to the cortex in the gyrus.
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Anten NPR, Miyazawa K, Hikosaka K, Nagashima H, Hirose T. Leaf nitrogen distribution in relation to leaf age and photon flux density in dominant and subordinate plants in dense stands of a dicotyledonous herb. Oecologia 1998; 113:314-324. [PMID: 28307815 DOI: 10.1007/s004420050382] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We studied the effects of photon flux density (PFD) and leaf position, a measure of developmental age, on the distribution of nitrogen content per unit leaf area (N area) in plants of different heights, in dense stands grown at two nitrogen availabilities and in solitary plants of the erect dicotyledonous herb Xanthium canadense. Taller more dominant plants received higher PFD levels and experienced a larger difference in relative PFD between their youngest and oldest leaves than shorter subordinate plants in the stands. Differences in PFD between leaves of solitary plants were assumed to be minimal and differences in leaf traits, found for these plants, could thus be mainly attributed to an effect of leaf position. In the solitary plants, N area decreased with leaf position while in the plants from the stands it decreased with decreasing relative PFD, indicating both factors to be important in determining the distribution of N area. Due to the effect of leaf position on N area, leaves of subordinate plants had a higher N area than older leaves of dominant plants which were at the same height or slightly higher in the canopy. Consequently, the N area distribution patterns of individual plants plotted as a function of relative PFD were steeper, and probably closer to the optimal distribution which maximizes photosynthesis, than the average distribution in the stand. Leaves of subordinate plants had a lower mass per unit area (LMA) than those of dominant plants. In the dominant plants, LMA decreased with decreasing relative PFD (and with leaf position) while in the subordinate plants it increased. This surprising result for the subordinate plants can be explained by the fact that, during the course of a growing season, these plants became increasingly shaded and newer leaves were thus formed at progressively lower light availability. This indicates that LMA was strongly determined by the relative PFD at leaf formation and to a lesser extent by the current PFD. Leaf N content per unit mass (N mass) was strongly determined by leaf position independent of relative PFD. This indicates that N mass is strongly ontogenetically related to the leaf-aging process while changes in N area, in response to PFD, were regulated through changes in LMA.
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Hikosaka K. Responsiveness of neurons in the posterior inferotemporal cortex to visual patterns in the macaque monkey. Behav Brain Res 1997; 89:275-83. [PMID: 9475635 DOI: 10.1016/s0166-4328(97)00073-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Using anesthetized and immobilized monkeys, responses of neurons in the posterior inferotemporal cortex to visual patterns were examined. Response properties were compared between the sulcus and the gyrus, extending between the anterior tip of the posterior middle temporal sulcus and the inferior occipital sulcus. Of 682 neurons tested, 37% in the sulcus (134/365) and 36% in the gyrus (113/317) responded to one or more patterns. The preference of neurons for patterns varied from neuron to neuron; some neurons responded selectively to one particular pattern, whereas others responded to two or more patterns. To evaluate response properties of neurons, two indices were calculated (the pattern preference index and the pattern selectivity index). The distributions of these indices in the sulcus did not differ significantly from those of the gyrus. Furthermore, the relationship between the pattern preference index and the pattern selectivity index for each neuron was almost the same in these two portions; most neurons responding to a small number of patterns showed inhibitory or weak responses to the worst pattern. In both portions, most neurons had receptive fields with small eccentricities and receptive field sizes were almost the same. These results suggest that the cortex in the sulcus in the posterior inferotemporal cortex is involved in the detection of features of visual patterns, similarly to the cortex in the gyrus.
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Watanabe M, Kodama T, Hikosaka K. Increase of extracellular dopamine in primate prefrontal cortex during a working memory task. J Neurophysiol 1997; 78:2795-8. [PMID: 9356427 DOI: 10.1152/jn.1997.78.5.2795] [Citation(s) in RCA: 195] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Increase of extracellular dopamine in primate prefrontal cortex during a working memory task. J. Neurophysiol. 78: 2795-2798, 1997. The dopamine innervation of the prefrontal cortex is involved importantly in cognitive processes, such as tested in working memory tasks. However, there have been no studies directly investigating prefrontal dopamine levels in relation to cognitive processes. We measured frontal extracellular dopamine concentration using in vivo microdialysis in monkeys performing in a delayed alternation task as a typical working memory paradigm and in a sensory-guided control task. We observed a significant increase in dopamine level in the delayed alternation task as compared both with the sensory-guided control task and the basal resting level. The increase was seen in the dorsolateral prefrontal but not in the arcuate or orbitofrontal areas. The increase appeared to reflect the working memory component of the task and was observed mainly in the lip areas of principal sulcus. Although there was no significant difference in dopamine level between delayed alternation and sensory-guided control tasks in the premotor area, significant increases in dopamine concentration were observed during both tasks as compared with the basal resting level, indicating the importance of premotor dopamine for the motor response itself.
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Funayama S, Hikosaka K, Yahara T. Effects of virus infection and growth irradiance on fitness components and photosynthetic properties of Eupatorium makinoi (Compositae). AMERICAN JOURNAL OF BOTANY 1997; 84:823. [PMID: 21708634 DOI: 10.2307/2445818] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We examined the effects of geminivirus infection on fitness components and on photosynthetic properties of the host plant, Eupatorium makinoi, grown at two irradiance levels in a natural-light greenhouse. Under the low-light condition (13% full sunlight), more than a half of the infected plants died during the 9-mo experiment, while most of uninfected plants survived. Growth rate was also lowered by infection. At high light (50% full sunlight), by contrast, virus infection did not cause mortality despite slight decrease in growth rate. Flowering occurred only at high light, and reproductive outputs of the plants were markedly reduced by the infection. Infected leaves had distinct yellow variegations and, when compared with uninfected leaves, they showed (1) comparable light-saturated photosynthetic rate per unit area, but (2) lower initial slope of light-response curve of photosynthesis on an incident irradiance basis. The lower initial slope was mainly due to reduction of light-harvesting chlorophyll-protein complexes in the variegated parts. Since the differences in plant performance, depending both on infection and on growth irradiance, were largely explained by the differences in growth rate and/or plant size, the reduced photosynthetic production in the infected plants would be a major factor explaining the inferior performance of the host plants.
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118
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Hikosaka K, Terashima I. Nitrogen Partitioning among Photosynthetic Components and its Consequence in Sun and Shade Plants. Funct Ecol 1996. [DOI: 10.2307/2390281] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Hikosaka K, Terashima I, Katoh S. Effects of leaf age, nitrogen nutrition and photon flux density on the distribution of nitrogen among leaves of a vine (Ipomoea tricolor Cav.) grown horizontally to avoid mutual shading of leaves. Oecologia 1994; 97:451-457. [DOI: 10.1007/bf00325881] [Citation(s) in RCA: 163] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/1993] [Accepted: 12/08/1993] [Indexed: 11/29/2022]
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Hikosaka K, Terashima I, Katoh S. Effects of leaf age, nitrogen nutrition and photon flux density on the distribution of nitrogen among leaves of a vine (Ipomoea tricolor Cav.) grown horizontally to avoid mutual shading of leaves. Oecologia 1994. [PMID: 28313732 DOI: 10.1007/bf00197597] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Effects of leaf age, nitrogen nutrition and photon flux density (PFD) on the distribution of nitrogen among leaves were investigated in a vine, Ipomoea tricolor Cav., which had been grown horizontally so as to avoid mutual shading of leaves. The nitrogen content was highest in newly developed young leaves and decreased with age of leaves in plants grown at low nitrate concentrations and with all leaves exposed to full sunlight. Thus, a distinct gradient of leaf nitrogen content was formed along the gradient of leaf age. However, no gradient of leaf nitrogen content was formed in plants grown at a high nitrate concentration. Effects of PFD on the distribution of nitrogen were examined by shading leaves in a manner that simulated changes in the light gradient of an erect herbaceous canopy (i.e., where old leaves were placed under increasingly darker conditions with growth of the canopy). This canopy-type shading steepened the gradient of leaf nitrogen content in plants grown at a low nitrogen supply, and created a gradient in plants grown at high concentrations of nitrate. The steeper the gradient of PFD, the larger the gradient of leaf nitrogen that was formed. When the gradient of shading was inverted, that is, younger leaves were subjected to increasingly heavier shade, while keeping the oldest leaves exposed to full sunlight, an inverted gradient of leaf nitrogen content was formed at high nitrate concentrations. The gradient of leaf nitrogen content generated either by advance of leaf age at low nitrogen availability, or by canopy-type shading, was comparable to those reported for the canopies of erect herbaceous plants. It is concluded that both leaf age and PFD have potential to cause the non-uniform distribution of leaf nitrogen. It is also shown that the contribution of leaf age increases with the decrease in nitrogen nutrition level.
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Iwai E, Yukie M, Watanabe J, Hikosaka K, Suyama H, Ishikawa S. A role of amygdala in visual perception and cognition in macaque monkeys (Macaca fuscata and Macaca mulatta). TOHOKU J EXP MED 1990; 161 Suppl:95-120. [PMID: 2082507 DOI: 10.1620/tjem.161.supplement_95] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
To elucidate the role of the amygdala in visual perception and cognition, the effects of ablations of the amygdala and inferotemporal cortex on several visual tasks were compared with each other, and also the distribution patterns of the projections between them were investigated. The findings indicate that the inferotemporal cortex plays a critical role in visual perception, cognition and memory, whereas the amygdala is involved fundamentally in controlling emotional and motivational behavior. However, the amygdala is concerned with vision in the following ways: It receives neutral visual information highly processed in the visual cortex, invests the information with emotional and motivational significance through interactions with the cortical and subcortical systems of emotion and motivation, and then it returns the information coded to the visual areas to be re-processed; to be consciously perceived in area TEO, and to be meaningfully cognized, recognized and memorized in areas TE and TEG. Therefore, two channel model regarding the mechanism of visual information processing in the inferotemporal cortex is proposed: A first channel is concerned with processing neutral information, while the second one, with processing meaning information coded emotionally and motivationally in the amygdala. In addition, the present studies demonstrate that area TEG, which is cytoarchitecturally a transitional area between areas TE and TG and whose functional significance has remained unclear, is involved significantly in visual cognition rather than visual perception.
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Iwai E, Yukie M, Watanabe J, Yaginuma S, Osawa Y, Hikosaka K. Two-stage model of visual pattern discrimination learning in macaque monkeys (Macaca mulatta and Macaca fuscata). TOHOKU J EXP MED 1990; 161 Suppl:79-93. [PMID: 2082506 DOI: 10.1620/tjem.161.supplement_79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
To investigate the nature underlying the process of pattern discrimination learning, a series of seven experiments on seven working assumptions were undertaken. The main findings are as follows. The pattern discrimination learning consists of two time-dependent stages: The initial or first learning stage is the period of performance at chance, and the succeeding or second stage is the period of performance from just above the chance to a criterion level. The duration of the first stage is dependent on the degrees of cue-response separations, whereas that of the second stage is independent of. During the first stage, monkeys do not attend to the discriminative cue even at small cue-response separations, whereas during the second stage, they achieve pattern discrimination, or pattern perception and cognition, regardless of cue-response separations. After having learned the first pattern task with a cue-response separation, they learned new pattern tasks by means of the second stage, showing marked saving of the duration of the first stage. The findings in the present studies indicate that the first stage of learning is predominantly involved in the process of attending to the discriminative cues remote from the response site (a selective attention to the cue), whereas the second stage is concerned with the process of perception and cognition of the discriminative cue.
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Gohji K, Goto A, Takenaka A, Arakawa S, Matumoto O, Hikosaka K, Kamidono S. Extragonadal germ cell tumor in the retrovesical region associated with Klinefelter's syndrome: a case report and review of the literature. J Urol 1989; 141:133-6. [PMID: 2535759 DOI: 10.1016/s0022-5347(17)40620-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We report a case of an extragonadal germ cell tumor from the retrovesical region associated with Klinefelter's syndrome. The patient presented with symptoms of macroscopic hematuria and micturition pain. An x-ray and digital examination were suspicious for prostatic carcinoma. However, needle biopsy of the tumor revealed embryonal cell carcinoma. Serum alpha-fetoprotein was 10,700 ng. per ml. Preoperatively, combined cytotoxic chemotherapy was administered and the antineoplastic effect was excellent. Serum alpha-fetoprotein rapidly returned to the normal range and the tumor volume decreased. Although the preoperative diagnosis was extragonadal germ cell tumor of the prostate, surgery revealed that the tumor originated from the retrovesical region. Orchiectomy and resection were performed. The resected tissue was mostly necrotic with a few viable cells of embryonal cell carcinoma, no metastatic lesions were detected in the lymph nodes and no masses were noted in the testes. Postoperatively, the patient was treated with cytotoxic chemotherapy. His condition has remained good with no clinical evidence of recurrence of the disease.
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Hikosaka K, Iwai E, Saito H, Tanaka K. Polysensory properties of neurons in the anterior bank of the caudal superior temporal sulcus of the macaque monkey. J Neurophysiol 1988; 60:1615-37. [PMID: 2462027 DOI: 10.1152/jn.1988.60.5.1615] [Citation(s) in RCA: 223] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
1. We examined the sensory properties of cells in the anterior bank of the caudal part of the superior temporal sulcus (caudal STS) in anesthetized, paralyzed monkeys to visual, auditory, and somesthetic stimuli. 2. In the anterior bank of the caudal STS, there were three regions distinguishable from each other and also from the middle temporal area (MT) in the floor of the STS and area Tpt in the superior temporal gyrus. The three regions were located approximately in the respective inner, middle, and outer thirds of the anterior bank of the caudal STS. These three regions are referred to, from the inner to the outer, as the medial superior temporal region (MST), the mostly unresponsive region, and the caudal STS polysensory region (cSTP), respectively. 3. The extent of MST and its response properties agreed with previous studies. Cells in MST responded exclusively to visual stimuli, had large visual receptive fields (RFs), and nearly all (91%) showed directional selectivity. 4. In the mostly unresponsive region, three quarters of cells were unresponsive to any stimulus used in this study. A quarter of the cells responded to only visual stimuli and most did not show directional selectivity for moving stimuli. Several directionally selective cells responded to movements of three-dimensional objects, but not of projected stimuli. 5. The response properties of cells in the superficial cortex of the caudal superior temporal gyrus, a part of area Tpt, external to cSTP were different from those of cells in the three regions in the anterior bank of the STS. Cells in Tpt were exclusively auditory, and had much larger auditory RFs (mean = 271 degrees) than those of acoustically-driven cSTP cells (mean = 138 degrees). 6. The cSTP contained unimodal visual, auditory, and somesthetic cells as well as multimodal cells of two or all three modalities. The sensory properties of cSTP cells were as follows. 1) Out of 200 cells recorded, 102 (51%) cells were unimodal (59 visual, 33 auditory, and 10 somesthetic), 36 (18%) cells were bimodal (21 visual+auditory, 7 visual+somesthetic, and 8 auditory+somesthetic), and four (2%) cells were trimodal. Visual and auditory responses were more frequent than somesthetic responses: the ratio of the population of cells driven by visual: auditory: somesthetic stimuli was 3:2:1. 2) Visual RFs were large (mean diameter, 59 degrees), but two-thirds were limited to the contralateral visual hemifield. About half the cells showed directional selectivity for moving visual stimuli. None showed selectivity for particular visual shapes.(ABSTRACT TRUNCATED AT 400 WORDS)
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Tsukamura M, Hikosaka K, Nishimura K, Hara S. Severe progressive subcutaneous abscesses and necrotizing tenosynovitis caused by Rhodococcus aurantiacus. J Clin Microbiol 1988; 26:201-5. [PMID: 3343320 PMCID: PMC266252 DOI: 10.1128/jcm.26.2.201-205.1988] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A case of severe progressive subcutaneous abscesses and necrotizing tenosynovitis of the right arm of a 30-year-old woman caused by Rhodococcus aurantiacus is reported.
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