Site-specific recognition of nanophase-separated surfaces of amphiphilic block copolymers by hydrophilic and hydrophobic gold nanoparticles.
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Journal Article↗
Biomedical subjects
Shigeru Watanabe
Publications and source records attributed to Shigeru Watanabe.
Towards a "virtual pigeon": a new technique for investigating avian social perception.
The purpose of the present study is to examine the applicability of a computer-generated, virtual animal to study animal cognition. Pigeons were trained to discriminate between movies of a real pigeon and a rat. Then, they were tested with movies of the computer-generated (CG) pigeon. Subjects showed generalization to the CG pigeon, however, they also responded to modified versions in which the CG pigeon was showing impossible movement, namely hopping and walking without its head bobbing. Hence, the pigeons did not attend to these particular details of the display. When they were trained to discriminate between the normal and the modified version of the CG pigeon, they were able to learn the discrimination. The results of an additional partial occlusion test suggest that the subjects used head movement as a cue for the usual vs. unusual CG pigeon discrimination.
Animals↗
Animal logics: decisions in the absence of human language.
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Animal Communication↗
Molecular design of novel non-planar heteropolycyclic fluorophores with bulky substituents: convenient synthesis and solid-state fluorescence characterization.
Novel indeno[1,2-b]benzo[4,5-e]pyran-11-one-type fluorophores exhibiting intense solid-state fluorescence were conveniently synthesized and the relation between their solid-state photophysical properties and the X-ray crystal structures were investigated, which demonstrates that non-planar structures with sterical hindered substituents prevent the fluorophores from forming short pi-pi contacts causing fluorescence quenching in the solid state.
Journal Article↗
Deficits in acquisition of spatial learning after dorsomedial telencephalon lesions in goldfish.
Acquisition of spatial learning is an important function of mammalian hippocampus. In order to identify the brain areas in teleost fish that are homologous to mammalian hippocampus, the present study examined the effects of lesions in the dorsal area of the caudal telencephalon of goldfish (Carassius auratus) on the acquisition of spatial learning. An open-field maze that was similar to the dry version of the Morris water maze was used. The task consisted of habituation and postoperative training to reach the position of the bait. Extramaze cues were visible in the habituation sessions in experiment 1, while they were blocked and not visible in the habituation sessions in experiment 2. Only in experiment 2, there was a significant deficit in the performance in the training sessions in the goldfish with damage to the dorsomedial area of the caudal telencephalon (DM). These data showed that blocking of the extramaze cues in the habituation sessions caused deficits in postoperative acquisition of spatial learning in the training sessions in the goldfish with DM lesions. Latent learning in the habituation sessions, however, eliminated the effects of the DM lesions on spatial learning. The present study suggests that the DM plays a critical role in acquisition of spatial learning.
Analysis of Variance↗
Auditory fear conditioning and conditioned stress raise NO(3) level in the Amygdala.
BACKGROUND: The conditioned fear response is considered to be acquired by experimental animals when tone information is combined with that of an electrical foot shock (unconditioned stimulus) in the amygdala. Nitric oxide biosynthesized in the brain is reportedly involved in several kinds of learning. METHODS: In this study, we continuously monitored the NO(3)(-) level, as a marker of nitric oxide production, in the amygdala starting before the application of tone and electrical foot shock stimuli together (conditioned group) or the tone stimulus alone (control group) on day 1, until after the tone information was given (both groups) on day 2, using the in vivo microdialysis method. RESULTS: The NO(3)(-) level of the conditioned group was increased on both day 1 and day 2, while that of the control group was not elevated on either day. Freezing behavior was observed in the conditioned but not the control rats. CONCLUSIONS: Although the sources of NO(3)(-) remain uncertain, these results suggest that nitric oxide is associated with auditory fear conditioning and the response to a conditioned stimulus.
Acoustic Stimulation↗
Language discrimination by Java sparrows.
Java sparrows (Padda oryzivora) were trained to discriminate English from Chinese spoken by a bilingual speaker. They could learn discrimination and showed generalization to new sentences spoken by the same speaker and those spoken by a new speaker. Thus, the birds distinguished between English and Chinese. Although auditory cues for the discrimination were not specified, this is the first evidence that non-mammalian species can discriminate human languages.
Animal Communication↗
Chronic intraperitoneal injection of interferon-alpha reduces serotonin levels in various regions of rat brain, but does not change levels of serotonin transporter mRNA, nitrite or nitrate.
Interferon-alpha therapy is associated with a high rate of depression, but the pathophysiological mechanisms remain unclear. The purpose of the present study was to investigate the effects of i.p. administered interferon-alpha on monoaminergic neurotransmission in the brain. The levels of monoamines and associated metabolites were measured in various regions of the rat brain using a high-performance liquid chromatography-electrochemical detection system. The serotonin transporter mRNA levels were also measured using in situ hybridization. After 1 day, dopamine turnover was diminished in the cortex. Norepinephrine turnover was decreased in most regions tested after 4 days. However, these changes were transient. After 14 days, serotonin turnover was increased in the frontal cortex and hippocampus in rats given a dose of 20 000 IU/kg; in the frontal cortex, hippocampus, amygdala, thalamus, hypothalamus and brainstem in those on 200 000 IU/kg; and in the thalamus and hypothalamus in those on 2 000 000 IU/kg (all P < 0.05). However, 14-day treatment did not significantly change serotonin transporter mRNA levels. Next, the question of whether interferon-alpha affects monoamine levels via induction of nitric oxide (NO), was investigated. However, there were no changes in either NO2- or NO3-, as markers of NO production, in any brain regions after 14-day treatment. These results suggest that chronic peripheral administration of interferon-alpha induces metabolic changes in the central serotonin system. Further investigation is needed to determine exactly how this cytokine affects the central serotonin system and to assess whether a central serotonin abnormality is involved in interferon-induced depression.
Animals↗
Relationship between aortic calcification and stroke in a mass screening program using a mobile helical computed tomography unit.
BACKGROUND: It is reported that there is a significant relationship between the calcification of the aortic arch detected by chest X-ray examination and stroke. However, the relationship between stroke and aortic calcification (AoC) detected during a mass screening using a mobile helical computed tomography (CT) unit remains unknown. METHODS AND RESULTS: The study population consisted of 2,618 subjects (1,345 men, and 1,273 women; mean age, 52.9+/-13.8 years) who participated in a mass CT screening for lung cancer and tuberculosis. In the present study, 28 subjects (18 men, and 10 women; mean age, 65.9+/-13.5 years) had a past history of cerebral infarction. There were no subjects with a past history of intracerebral or subarachnoid hemorrhage. The frequency of AoC was significantly higher in the infarction group who were older than 50 years of age. In logistic regression analysis, the AoC was a stronger contributor of infarction than sex, age, and risk factors. Furthermore, the odds ratio of AoC for subjects with a past history of infarction increased as the number of calcified segments increased, and these values were 1.82 (95% confidence interval (CI) 1.06-3.15) in men, and 2.53 (95% CI 1.12-5.75) in women. CONCLUSIONS: These results suggest that detection of AoC during mass chest screening using a mobile helical CT unit is an effective way to evaluate the risk of cerebral infarction.
Adolescent↗
Effects of hippocampal lesions on conditional discriminations in rats.
Effects of hippocampal lesions on conditional discrimination were examined in rats. Rats were trained in a conditional drug discrimination paradigm using pentobarbital. They were able to learn the discrimination. After hippocampal lesions, all rats maintained discrimination. Thus a hippocampal lesion had no effect on retention of the conditional discrimination with drugs. Another group was trained in the same conditional discrimination except that the conditional stimuli were two different flashing lights. Similarly to the drug discrimination, only one of the two light conditioning stimuli was presented in one training session. No rat was able to learn the discrimination. New rats were trained in conventional conditional discrimination, in which the two conditional stimuli (flashing lights) were repeatedly presented within one training session. Hippocampal lesions made after learning this discrimination had no effect on retention. The present study reveals that the hippocampus does not have a crucial role in conditional discrimination learning when conditional stimuli were drugs and that rats could not learn conditional discrimination when two external conditional stimuli were presented in a similar way to the internal stimuli (drug discrimination paradigm).
Animals↗
Spatial memory activation of the parietal cortex measured with near-infrared spectroscopic imaging in the finger-maze of the Morris water maze analogue for humans.
To assess the cortical regions involved in learning spatial navigation, changes in oxyhemoglobin volume were measured with near-infrared spectroscopy in a task analogous to the Morris water maze. The blindfolded participants (Ps) were allowed to search the area inside the circular ring (20 cm) until they reached a goal (1 cm). The sitting and starting positions were randomly varied across trials, but the goal was in a fixed position so that the Ps could learn the allocentric spatial relationship between the goal and the experimental room. There was a significant sex difference (p < 0.05) in the present task, showing that performance in males was better than that in females. With this task, we measured brain activation in the first training trial, the probe test, and the motor-control trials. In the first trial, dorsolateral prefrontal and parietal cortices were activated. In the probe test, only the dorsolateral prefrontal regions were activated. These results suggest that the parietal cortex is critical for acquisition of spatial memory.
Adult↗
Effects of partial hippocampal lesions by ibotenic acid on repeated acquisition of spatial discrimination in pigeons.
Pigeons were trained on a spatial discrimination task using a repeated acquisition procedure. In this procedure, the pigeons were trained to discriminate between the positions of three keys. One of them was designated the correct key. When the subjects reached the criterion, the discrimination task was changed, with one of two previously incorrect keys now being made the correct key. This procedure was repeated at least 15 times. Then, lesions to the whole hippocampus, the medial hippocampus or to the lateral hippocampus were made by injections of ibotenic acid (Experiment 1). Only the subjects with damage to the whole hippocampus showed deficits in learning after the lesions. The deficits were similar to those caused by aspiration lesions /37/. Knife cuts separating the medial and lateral hippocampi were made in Experiment 2. The subjects did not show deficits in the spatial discrimination task after the sections. Although studies of the connectivity in the avian hippocampus suggested functional differences between the medial and lateral hippocampi, the present results show that pigeons can learn spatial discrimination with the medial and lateral parts of hippocampus separated.
Animals↗
Spatial memory and hippocampal function in a non-foodstoring songbird, the zebra finch (Taeniopygia guttata).
Spatial memory and hippocampal function have as yet been investigated mainly in pigeons and food storing songbirds. We show here that the zebra finch, a songbird not specialized in food storing and caching, is also able to learn a spatial memory task and uses a spatial map for finding food in a 'dry water maze'. Hippocampal lesions prevent learning and retention of this spatial task. The immediate early gene (IEG) products Zenk and Fos are expressed within the hippocampus when the bird is learning the task. Spatial learning cannot be assigned to any hippocampal subregion; IEG expression within the hippocampus is patchy and seems almost arbitrarily located. The IEG activation pattern in spatial memory experiments is compared with those in other learning experiments with zebra finches.
Animals↗
A case of hepatic angiosarcoma supplied by both hepatic artery and portal vein.
Liver neoplasms, whether they are benign or malignant, are usually fed by the hepatic artery. We experienced a case of hepatic angiosarcoma supplied by both hepatic artery and portal vein. Since there are currently no specific laboratory tests to diagnose hepatic angiosarcoma, it is important to detect suspect cases from imaging features. This unique hemodynamic property was detected on computed tomography (CT) during hepatic arteriography and CT during hepatic arterioportography. If any imaging examinations indicate the liver tumor to be fed by the portal vein, hepatic angiosarcoma should be suspected.
Angiography↗
Chronic food restriction enhances memory in mice--analysis with matched drive levels.
We compared the effects of chronic and acute food deprivation on learning and memory using a dry-type water maze, active avoidance and passive avoidance in C57BL/6L mice. The drive level of the animals--under acute and chronic food deprivation--was matched by a progressive ratio schedule. Both deprivations led to a high degree of activity in the animals; however, the animals on an acute dietary restriction did not exhibit a significantly better performance than those on ad libitum feeding, while those on a chronic food deprivation exhibited memory enhancement. These effects were subtle and were found at a later stage of learning. These findings suggest that chronic food restriction induces memory consolidation or resistance to memory reduction in addition to increased activity.
Animals↗
Foot-use laterality in the Japanese jungle crow (Corvus macrorhynchos).
Laterality of foot-use behaviour was examined in jungle crows (Corvus macrorhynchos). Consistency of laterality was also verified in comparison with two different behaviours. One was beak-scratching, and another was food-holding. Significant bias of foot-use laterality was found in 11 of 13 tested subjects for beak-scratching and in 10 of 12 tested subjects for food-holding. Bias of foot-use laterality was not common among footed subjects, suggesting no population-level bias. However, a significant number of footed subjects (10 of 12) who were tested in both behaviours showed consistent laterality irrespective of behavioural differences. These results suggest that jungle crows have strong individual-level laterality in foot-use behaviour.
Animals↗
Lesions in the basal ganglion and hippocampus on performance in a Wisconsin Card Sorting Test-like task in pigeons.
Previous studies of LPO (lobus parolfactorium) and hippocampal lesions in pigeons suggest function of cognitive flexibility in LPO and memory consolidation in hippocampus [Watanabe S. Effects of hippocampal lesions on repeated acquisition of spatial discrimination in pigeons. Behav Brain Res 2001;120:59-66. ; Watanabe S. Effects of LPO lesions on repeated acquisition of spatial discrimination in pigeons. Brain Behav Evol 2002;58:333-342. ]. Here, a test similar to the Wisconsin Card Sorting Test was applied to pigeons. The test consisted of four discriminations, namely red-green color discrimination and its reversal, left-right spatial discrimination and its reversal. In each trial stimuli were presented until the correct choice occurred. Ten successive correct trials without wrong response were defined as the criterion of discrimination. When the subjects reached the criterion in one discrimination, they were trained on one of three other discrimination tasks in the next session. These four discriminations were trained repeatedly in random sequence. After the birds have been well learned the WCST-like task, their hippocampus or lobus parolfactorium (LPO), the avian basal ganglion, was damaged. A sham lesion group received anesthesia only. Both lesions impaired the WCST-like test. Lesions of the LPO increased the number of errors, while the hippocampal lesions increased the number of trials to reach the criterion only. The number of errors reflects difficulty in finding the correct stimulus or cognitive flexibility, while the number of trials reflects difficulty in stable responding or memory consolidation. The present results suggest that LPO has the function of cognitive flexibility.
Analysis of Variance↗
Amygdalic levels of dopamine and serotonin rise upon exposure to conditioned fear stress without elevation of glutamate.
Conditioned fear is an artificial stress, induced by a stimulus, such as a tone, that does not elicit fear in nature. This fear response is acquired by experimental animals when tone is combined with an unconditioned stimulus, such as electrical foot shock. The amygdala is considered to be the area involved in acquisition, consolidation and recall of fear. A series of previous pharmacological studies showed antagonists of dopamine D1 and D2, glutamate N-methyl-D-asparatate and (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors to prevent the acquisition of conditioned fear. However, little is known about the types of neurotransmitters released when conditioned fear is acquired and recalled. The present study was designed to continuously monitor changes in extracellular levels of glutamate, dopamine and serotonin in the amygdala, at the acquisition of conditioned fear on Day 1 and at fear recall in response to a tone as a conditioned stimulus on Day 2, using the in vivo microdialysis method. Glutamate was elevated only on Day 1, while dopamine and serotonin rose on both days. The periods of elevated dopamine and serotonin were longer on Day 1 than on Day 2. These results suggest that greater amounts of glutamate, dopamine and serotonin are necessary for acquisition than for recall of conditioned fear.
Amygdala↗