Effects of magnesium pemoline and dextroamphetamine on human learning

Two central nervous system stimulants, magnesium pemoline and dextroamphetamine, were tested to see if they facilitate learning in human subjects. Subjects under placebo learned faster than the subjects under any of the several doses of magnesium pemoline; however, none of these differences reached statistical significance. Subjects who received dextroamphetamine learned significantly more slowly than those who received placebo.     

Magnesium pemoline: effect on avoidance conditioning in rats

Rats administered 20 milligrams of magnesium pemoline per kilo gram of body weight learned to avoid shock in a jump-out apparatus in fewer trials than did controls. However, the results suggested that the principal effect of the drug was to facilitate the avoidance behavior of those animals that tended to "freeze" in response to electric grid shock. No differences in retention were observed between experimental and control animals that had achieved equal levels of learnine.     

Magnesium pemoline: enhancement of brain RNA polymerases

The stimulation by magnesium pemoline of systems that synthesize brain nucleic acid was studied in vivo and in vitro. There are differential effects between true RNA polymerase and pseudo-RNA polymerase. The selective stimulation of true RNA polymerase by magnesium pemoline was not observed with stimulants of the central nervous system and psychotropic agents.     

贝伐珠单抗类似药SMMU-13对食蟹猴的毒性

为了探讨贝伐珠单抗类似药SMMU-13重复静脉注射对食蟹猴的安全性,采用毒理学评价方法,将30只食蟹猴按体重随机分为溶媒对照组、阳性对照组,低、中、高剂量组,每组6只,雌雄各半。低、中、高剂量组给药量分别为2、10和50mg/kg;阳性对照组给予50mg/kg贝伐珠单抗注射液;溶媒对照组给予SMMU-13安慰剂。给药体积均为2mL/kg。每周给药2次,共4个给药周期,恢复期4周。期间进行各项毒理学指标检测。试验结果发现:与自身给药前d0相比,给药期间中、高剂量组及阳性对照组的乳酸脱氢酶(LDH)和甘油三脂(TG)升高;高剂量组及阳性对照组雄性动物股骨骨骺板软骨细胞增生,钙化成骨不良,给药部位近端血管及周围损伤。其余各项指标毒理学指标未见明显异常变化。以上结果表明,SMMU-13主要毒性靶部位为股骨骨骺及给药局部。在本实验条件下安全剂量为2mg/kg,毒性剂量为10mg/kg,与等剂量阳性对照药物毒性反应基本类似。本研究为贝伐珠单抗类似药SMMU-13的临床用药提供了安全用药依据。     

Reinforcement magnitude as a determinant of performance decrement after electroconvulsive shock

The intensity of a foot shock may be a determinant of the rate at which an avoidance response becomes resistant to disruption by electroconvulsive shock. Mice were trained, one trial a day, in a passive avoidance learning task, with one of three foot-shock intensities. Electroconvulsive shock was administered at various intervals after each trial. At all foot-shock intensities, electroconvulsive shock given 10 seconds after each training trial was eflective in disrupting learning. Where electroconvulsive shock was given at longer intervals after each trial, those animals learning at low intensities of foot shock showed greater impairment of performance than those learning at high intensities.     

Alcohol and amitriptyline effects on skills related to driving behavior

Three motor-skill tests related to driving ability were given to 21 healthy young volunteers after administration of various combinations of amitriptyline, placebo, and alcohol. It was found that the tricylic antidepressant added to the deleterious effects of alcohol.     

Magnesium pemoline: failure to affect in vivo synthesis of brain RNA

The effect of magnesium pemoline on the synthesis of brain RNA in vivo was studied. No significant effect either on the concentration of RNA or on the uptake of H(3)-uridine into RNA was detected.     

Pemoline and magnesium hydroxide: lack of effect on RNA and protein synthesis

Brain RNA polymerase isolated from rats treated with pemoline and magnesium hydroxide (Cylert) was not more active than enzyme from control animals. The drug did not increase enzymic activity in vitro. Pemoline did not significantly affect either RNA or protein synthesis in suspensions of Ehrlich ascites carcinoma cells.     

Attentional modulation of neural processing of shape, color, and velocity in humans

Positron emission tomography (PET) was used to measure changes in regional cerebral blood flow of normal subjects, while they were discriminating different attributes (shape, color, and velocity) of the same set of visual stimuli. Psychophysical evidence indicated that the sensitivity for discriminating subtle stimulus changes was higher when subjects focused attention on one attribute than when they divided attention among several attributes. Correspondingly, attention enhanced the activity of different regions of extrastriate visual cortex that appear to be specialized for processing information related to the selected attribute.     

Memory performance of chemical workers exposed to polybrominated biphenyls

Twenty-five chemical workers who manufactured polybrominated biphenyls (PBB's) were given objective tests of learning and memory. Although this group had high concentrations of PBB's in adipose tissue, mean scores on all memory tests were normal. The PBB concentration was not correlated with memory performance; the most contaminated workers showed no evidence of memory dysfunction.     

Stimulus preferences and imprinting

Pekin ducklings were tested with respect to their preference for approaching one of two simultaneously presented, rotating, silent duck decoys, painted in a variety of colors or patterns. Some of the ducklings had not been given any previous visual experience other than that gained in a 20-minute introduction to the empty apparatus; others had previously been given the opportunity to follow one particular decoy for 20 minutes. The decoys could be grouped into three categories: those in the first category were treated as equivalent, that is, so long as the duckling had followed one of these models it would approach either. The decoys of the second category were ones to which "imprinting" occurred, that is, the ducklings showed a decided preference for the model they had originally followed, whichever it was. The third category included models, one of which was always preferred, though the controls showed no such preference. The effects of the imprinting procedure vary with the stimuli presented.     

Crossmodal interactions between olfactory and visual learning in Drosophila

Different modalities of sensation interact in a synergistic or antagonistic manner during sensory perception, but whether there is also interaction during memory acquisition is largely unknown. In Drosophila reinforcement learning, we found that conditioning with concurrent visual and olfactory cues reduced the threshold for unimodal memory retrieval. Furthermore, bimodal preconditioning followed by unimodal conditioning with either a visual or olfactory cue led to crossmodal memory transfer. Crossmodal memory acquisition in Drosophila may contribute significantly to learning in a natural environment.     

Nimodipine facilitates associative learning in aging rabbits

Nimodipine is one of several dihydropyridines that block calcium channels. Originally administered to improve cerebral blood flow in elderly patients with chronic cerebrovascular disorders, nimodipine was noted to facilitate learning. These observations led to the present investigation of the effects of nimodipine on associative learning in aging rabbits. Nimodipine accelerated acquisition of conditioned eye-blink in both young and aging rabbits without altering the amplitude of responses to the conditioned or unconditioned stimuli or causing nonspecific responding. Thus, nimodipine may be a candidate for an effective treatment for age-related learning deficits.     

Marihuana: standardized smoke administration and dose effect curves on heart rate in humans

A spirometer was used to deliver marihuana and placebo smoke to human subjects. This procedure produced linear dose-effect curves on heart rate and replicable dose effects in individual subjects. No differences were observed between experienced and inexperienced smokers in responsiveness to heart rate increases produced by marihuana.     

Cannabis and temporal disintegration in experienced and naive subjects

The effects of 3.3 and 6.6 milligrams of Delta(9)-tetrahydrocannabinol and of placebo on performance of three cognitive tasks were compared for naive subjects and experienced cannabis smokers. No differences in performance or reported subjective effects were found between these two groups. A significant decrement was found following dosage at both levels, replicating earlier findings of temporal disintegration during cannabis intoxication.     

Adrenaline and noradrenaline: relation to performance in a visual vigilance task

Concentrations of adrenaline and noradrenaline in the circulating blood were measured in blood samples taken from subjects as they performed a visual vigilance task or viewed movies, both under identical conditions. For those subjects whose vigilance performance deteriorated it was concluded that the concentration of circulating adrenaline decreases as a function of time in a vigilance task but not under "relaxed" conditions, such as watching motion pictures. crementers under "relaxed"conditions.     

Citrus fruits maturity detection in natural environments based on convolutional neural networks and visual saliency map

Citrus fruits do not ripen at the same time in natural environments and exhibit different maturity stages on trees, hence it is necessary to realize selective harvesting of citrus picking robots. The visual attention mechanism reveals a physiological phenomenon that human eyes usually focus on a region that is salient from its surround. The degree to which a region contrasts with its surround is called visual saliency. This study proposes a novel citrus fruit maturity method combining visual saliency and convolutional neural networks to identify three maturity levels of citrus fruits. The proposed method is divided into two stages: the detection of citrus fruits on trees and the detection of fruit maturity. In stage one, the object detection network YOLOv5 was used to identify the citrus fruits in the image. In stage two, a visual saliency detection algorithm was improved and generated saliency maps of the fruits; The information of RGB images and the saliency maps were combined to determine the fruit maturity class using 4-channel ResNet34 network. The comparison experiments were conducted around the proposed method and the common RGB-based machine learning and deep learning methods. The experimental results show that the proposed method yields an accuracy of 95.07%, which is higher than the best RGB-based CNN model, VGG16, and the best machine learning model, KNN, about 3.14% and 18.24%, respectively. The results prove the validity of the proposed fruit maturity detection method and that this work can provide technical support for intelligent visual detection of selective harvesting robots.

     

Pharmacological modulation of perceptual learning and associated cortical reorganization

The pharmacological basis of perceptual learning and associated cortical reorganizations remains elusive. We induced perceptual learning by Hebbian coactivation of the skin of the tip of the right index finger in humans. Under placebo, tactile two-point discrimination was improved on the coactivated but not on the left index finger. This augmentation was blocked by an N-methyl-D-aspartate-receptor blocker, but doubled by amphetamine. No drug effects were found on the left index finger. The individual amount of cortical reorganization as assessed by mapping of somatosensory evoked potentials was linearly correlated with the pharmacological modulation of discrimination thresholds, implying that perceptual learning and associated cortical changes are controlled by basic mechanisms known to mediate and modulate synaptic plasticity.     

Delta 9-tetrahydrocannabinol: aversive effects in rat at high doses

Water-deprived rats were administered a single dose of Delta(9)-tetrahydrocannabinol either orally or intraperitoneally immediately after their first taste of a saccharine solution. In tests beginning 47 hours after drug administration, a dose-related reversal of rats' normal preference for saccharine was found. The data suggest that the drug produces aversive effects at doses of 1 to 32 milligrams per kilogram.     

Recovery of memory after amnesia induced by electroconvulsive shock

Electroconvulsive shock given to rats immediately after one-trial avoidance learning produced a significant amnesic effect 24 hours later; this amnesia had largely disappeared in further retention tests 48 and 72 hours after treatment. This result puts in question a basic assumption implicit in most memory consolidation studies that such amnesic effects will be permanent.