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PubMedDate not supplied

Multiple- and single-unit activity in area 32 (prelimbic region) of the medial prefrontal cortex during Pavlovian heart rate conditioning in rabbits.

Data from both brain lesion and brain stimulation experiments suggest that area 32 of the medial prefrontal cortex (prelimbic area) participates in the acquisition and/or expression of conditioned bradycardia. This report describes experiments designed to determine whether cells in this area of the brain exhibit changes in neural activity during classical conditioning that can be related to these learned heart rate changes. Thus, multiple- and single-unit activity was recorded from area 32 in rabbits during Pavlovian heart rate (HR) conditioning. In the first experiment, neuronal discharge recorded from chronically implanted multiple-unit electrodes in the superficial and deep layers of area 32 increased systematically in response to the presentation of tone conditioned stimuli (CS) paired with paraorbital electric shock as the unconditioned stimulus (US). This tone-evoked increase in multiple-unit activity (MUA) closely paralleled the acquisition of the decelerative HR conditioned response in animals that received paired CS/US presentations, but was of smaller amplitude in animals given unpaired CS/US presentations. Tone-evoked increases in MUA also occurred during tone-alone presentations prior to training, but this activity declined over trials. During extinction, CS-evoked MUA increases also declined over trials. These findings suggest that the CS-evoked increase in neuronal activity in area 32 was associatively produced. A second experiment examined the CS-evoked response of single units (n = 98) in area 32 during differential Pavlovian conditioning, in which one tone (CS+) was consistently followed by the paraorbital shock US and a second tone (CS-) was not. Four types of cells were found: (1) 32% of the cells studied showed no change in response to either CS+ or CS- presentation, (2) 48% showed CS-evoked increases to either CS+ or CS-, (3) 14% showed CS-evoked decreases to CS+ or CS-, and (4) 7% showed a biphasic response, in which an increase was followed by a decrease in activity. These cell types are similar to those previously found in the more dorsal anterior cingulate cortex (area 24) and frontal eyefields (area 8). However, a major difference between the present findings and those of our previous studies of areas 8 and 24 is that in several instances changes in CS-evoked activity in area 32 were significantly greater in response to the CS- than to the CS+, suggesting that some cells in the prelimbic region may code the absence of aversive stimulation, that is, a period of relative "safety."

Acoustic Stimulation↗

PubMedDate not supplied

[Techniques for nutrition education in particular for maternal and compulsory schools (author's transl)].

After an introduction on the various factors involved in food habits of humans, the A. is calling the attention on the importance of nutrition education, examining then some of the programs in use. Already in the maternal school the child can learn nutrition with applicative plays. It is compulsory to teach and follow also the in parents. For the compulsory school the nutrition should be taught as such or integrated in other courses as geography, history, mathematics and science. For adults the deep-seated food habits are making more difficult the educational programs. For successful results in nutrition education is essential that the programs are well planned and carried out from well trained personnel not only in nutritional sciences but also in education, cultural anthropology, psicology and sociology.

Adolescent↗

PubMedDate not supplied

Report of 100 open inguinal hernia repairs using a 2-cm incision: a novel technique.

We report a novel open technique for the repair of inguinal hernias using a 2-cm incision. This allows bilateral cases to be performed safely as day case procedures, where laparoscopic repair is not possible. A 2-cm incision is made over the deep inguinal ring. Blunt dissection distracts the cord and hernial sac, which can be dissected and reduced. A stapler is used to secure mesh through an incision too small to allow satisfactory suturing. This is a fast, safe, and easy-to-learn technique that produces a good repair with minimal bruising and quick wound healing. It is a useful substitute to laparoscopic totally extraperitoneal procedure (TEP) repair where this is not possible.

Ambulatory Surgical Procedures↗

PubMed1996

Multiagent reinforcement learning in the Iterated Prisoner's Dilemma.

Reinforcement learning (RL) is based on the idea that the tendency to produce an action should be strengthened (reinforced) if it produces favorable results, and weakened if it produces unfavorable results. Q-learning is a recent RL algorithm that does not need a model of its environment and can be used on-line. Therefore, it is well suited for use in repeated games against an unknown opponent. Most RL research has been confined to single-agent settings or to multiagent settings where the agents have totally positively correlated payoffs (team problems) or totally negatively correlated payoffs (zero-sum games). This paper is an empirical study of reinforcement learning in the Iterated Prisoner's Dilemma (IPD), where the agents' payoffs are neither totally positively nor totally negatively correlated. RL is considerably more difficult in such a domain. This paper investigates the ability of a variety of Q-learning agents to play the IPD game against an unknown opponent. In some experiments, the opponent is the fixed strategy Tit-For-Tat, while in others it is another Q-learner. All the Q-learners learned to play optimally against Tit-For-Tat. Playing against another learner was more difficult because the adaptation of the other learner created a non-stationary environment, and because the other learner was not endowed with any a priori knowledge about the IPD game such as a policy designed to encourage cooperation. The learners that were studied varied along three dimensions: the length of history they received as context, the type of memory they employed (lookup tables based on restricted history windows or recurrent neural networks that can theoretically store features from arbitrarily deep in the past), and the exploration schedule they followed. Although all the learners faced difficulties when playing against other learners, agents with longer history windows, lookup table memories, and longer exploration schedules fared best in the IPD games.

Algorithms↗

PubMed1999

Approaches to studying in people with hearing loss.

BACKGROUND: There has been little research on the experiences of students with hearing loss in higher education. It has, however, been suggested that children with hearing loss adopt different strategies and styles and that this leads to differences in their academic performance. AIMS: This investigation compared students in higher education with and without hearing loss in terms of their approaches to studying. SAMPLES: We compared 382 students with hearing loss taking courses by distance learning with the Open University and a comparison group of 190 students taking the same courses with no declared form of disablement. METHODS: A questionnaire containing a shortened and adapted version of the Approaches to Studying Inventory was distributed in a postal survey. RESULTS: Students with postvocational hearing loss obtained higher scores than the comparison group on deep approach, and those with postvocational deafness also obtained higher scores on the use of evidence and logic. Students with prevocational deafness obtained higher scores on reproducing orientation than the comparison group, and in particular on improvidence. All of the subgroups of students with hearing loss obtained higher scores than the comparison group on fear of failure. CONCLUSIONS: The impact of hearing loss on cognitive aspects of studying appears to be relatively slight. Future research might focus instead upon its affective consequences and its effects upon a student's self-concept.

Achievement↗

PubMed2004

[Paul D. Choy: A life for learning].

Paul D. Choy was born on February 26th, 1896. He spent his childhood in Japan and America, and he returned to Korea when he turned twenty one years old. He graduated from Severance Union Medical College in 1921. After graduating the college, he went to Peking Union medical College to study parasitology. He came back to Korea after one year as the first parasitologist in Korea. On returning, he took the charge of the clinical laboratory of Severance Hospital. Before long he made another journey for study to Canada. He spent two years in Toronto University studying pathology. After studying pathology, he challenged a new field of medicine. It was medical jurisprudence. He stayed two years in Japan in order to earn his doctorate in medical jurisprudence in Tohoku Imperial College. This time he returned as the first specialist in medical jurisprudence in Korea. His field of study was not confined to medical field. He had a deep interest in current situation in Manchuria and Mongol, and wrote a book on this matter. His interest also extended to the history of ancient Korean people. He made extensive studies on this subject, which resulted in publishing a huge work on the origin of Korean people and it ancient history. He was a true pioneer of medicine in Korea and his life was characterized by endless quest for learning.

Education, Medical↗

PubMed1997

Surgery of the thoracic aorta using deep hypothermic total circulatory arrest. Are there neurological consequences other than frank cerebral defects?

OBJECTIVE: Deep hypothermic total circulatory arrest has reduced primary morbidity and mortality in thoracic aortic surgery. Although frank neurological deficits have been proven to be a rare complication of this technique, the rate of subtle but irreversible neuropsychological disorders remains unknown. METHODS: A total of 23 patients (15 male, 8 female) who had undergone surgery for dissection or aneurysm of the thoracic aorta using deep hypothermic total circulatory arrest (mean 25.5 min, range 10-75 min) were studied retrospectively. The mean follow-up was 17 months. The following psychometric tests were conducted: a computer-based test battery to assess tonic alertness and sustained attention, the trail making test (TMT part A and B), the Münchner Gedächtnistest and a verbal learning test. In addition, a cerebral dopamine D2 receptor scintigraphy (using the SPECT technique) was performed. For comparison, 10 healthy subjects were studied. RESULTS: With regard to tonic alertness, 69.6 and 30.4% were below the 50th and 10th centiles, respectively, according to age- and education-corrected standard values. The impairment in sustained attention correlated significantly with the duration of the circulatory arrest. On the tests assessing short-term memory, the patients scored 30% below their age- and education-corrected peers. In terms of long-term memory, 60.9 and 39.1% of the patients were below one and two standard deviations, respectively. Concerning speed of information processing whilst 78.3% of the patients were below the 50th and 21.7% below the 10th centile. Indicative of some persistent and functional brain alteration, the dopamine D2 receptor binding was significantly reduced when compared with healthy subjects. CONCLUSIONS: These data prove a substantial and chronic reduction of higher cognitive function in some of the patients who underwent cardiac surgery using deep hypothermic total circulatory arrest; this was accompanied by a depression of the cerebral dopamine D2 receptor binding.

Adult↗

PubMed2003

[Complications with femoral access in cardiac cathetization. Impact of previous systematic femoral angiography and hemostasis with VasoSeal-ES collagen plug].

INTRODUCTION AND OBJECTIVES: Most cardiac catheterizations are performed via femoral artery access, and hemostatic devices are commonly used. We evaluate the relationship between the strategy used for femoral arteriography and the use of VasoSeal-ES, and local vascular complications. PATIENTS AND METHOD: Prospective study of 540 consecutive catheterizations with systematic femoral artery and sheath angiography. VasoSeal-ES was used in 427 patients. Predictors of local vascular complications such as patient-related factors, anatomy and hemostasis were analyzed. Variables related to failure of the collagen plug were also studied. RESULTS: Punctures of the common femoral artery occurred in 35.9% of all patients (16% in the deep femoral artery and its ostium). Spasm was evident in 18% (ranging from 58.1% in the deep femoral artery to 5.2% in the common femoral artery). Puncture at the site of ramification was seen in 11.3%. Angiographically significant atheroma was seen in 17.8%. The femoral head was a valid landmark for the common femoral artery in only 63.9% of the pateints. Risk factors for local vascular complications were punctures of the common femoral artery, female sex and failure of VasoSeal-ES to achieve hemostasis (15.8% in the first two months of use, 5.2% in the last months of the study). Complications involving superficial and deep femoral arteries occurred in 6.7% and 1.2% of the patients, respectively, in contrast to 0.6% involving the common femoral artery. Variables related to collagen plug failure were patient-related factors, weight less than 55 kg, operator-related factors and the learning curve. CONCLUSIONS: Systematic femoral angiography provides data that aids the choice of the best hemostasis procedure to reduce local vascular complications. Punctures of the common femoral artery were more frequent than expected, and were associated with a higher complication rate. VasoSeal-ES is a safe and useful method of hemostasis, and its infrequent failures were associated with high complication rates that were substantially reduced with experience.

Aged↗

PubMed2003

Perception.

The article is an overview of some central philosophical problems associated with perception. It discusses what distinguishes perception from other sensory capacities and from conception. It discusses anti-individualism, a view according to which the nature of a perceptual state is dependent not just causally but for its identity or 'essence' on relations to a normal environment in which systems containing that state were formed. It discusses different views about epistemic warrant. By emphasising the deep ways in which human and animal perceptual systems, especially visual systems, are similar, it criticises a dominant view of the last century, in both philosophy and large parts of psychology, according to which a range of sophisticated supplementary abilities have to be learned before a child can perceive objective features of the physical world.

Humans↗

PubMed2006

Local and descending circuits regulate long-term potentiation and zif268 expression in spinal neurons.

Long-term potentiation (LTP), a use dependent long-lasting modification of synaptic strength, was first discovered in the hippocampus and later shown to occur in sensory areas of the spinal cord. Here we demonstrate that spinal LTP requires the activation of a subset of superficial spinal dorsal horn neurons expressing the neurokinin-1 receptor (NK1-R) that have previously been shown to mediate certain forms of hyperalgesia. These neurons participate in local spinal sensory processing, but are also the origin of a spino-bulbo-spinal loop driving a 5-hydroxytryptamine 3 receptor (5HT3-R)- mediated descending facilitation of spinal pain processing. Using a saporin-substance P conjugate to produce site-specific neuronal ablation, we demonstrate that NK1-R expressing cells in the superficial dorsal horn are crucial for the generation of LTP-like changes in neuronal excitability in deep dorsal horn neurons and this is modulated by descending 5HT3-R-mediated facilitatory controls. Hippocampal LTP is associated with early expression of the immediate-early gene zif268 and knockout of the gene leads to deficits in long-term LTP and learning and memory. We found that spinal LTP is also correlated with increased neuronal expression of zif268 in the superficial dorsal horn and that zif268 antisense treatment resulted in deficits in the long-term maintenance of inflammatory hyperalgesia. Our results support the suggestion that the generation of LTP in dorsal horn neurons following peripheral injury may be one mechanism whereby acute pain can be transformed into a long-term pain state.

Animals↗

PubMed1989

Failure to find residual memory deficits in monkeys after repeated HPNS.

Squirrel monkeys (n = 8) were equated on learning and memory tasks before sustaining 3 separate dives in a laboratory compression chamber. Associative memory was carefully monitored 1 wk before and 3 wk immediately after each dive. The first dive was a shallow, subseizure control dive and the subsequent 2 dives were deep, seizure-inducing dives. Half of the animals were always compressed in He-O2 and half in He-N2-O2 gas, which is known to increase the depth at which tremors and seizures occur. After the control dive there was a slight (10% average) decline in memory performance, but the decline was temporary and recovery was complete by the second postdive week. There was no evidence of residual memory impairments after either of the 2 subsequent seizure-inducing dives. Although addition of nitrogen to the breathing gas significantly elevated thresholds for tremors, it had no differential effect on memory scores. These results are in agreement with studies of human divers that show either no residual impairments or transient, fully recoverable cognitive symptoms after diving.

Animals↗

PubMed1995

The immune self: a selectionist theory of recognition, learning, and remembering within the immune system.

In this paper, I have briefly explored metaphors shared by the immune and nervous systems and shown that this exercise can lead to the elucidation of common principles of organization, as well as to predictions concerning how the immune system functions. Metaphor itself undoubtedly reflects the way in which we categorize and retrieve information 44], so it is not surprising that the deep processes of language tend to sample information from related data categories. Although the nervous and immune systems are obviously not the same and metaphors are indeed just that, my primary goal has been to suggest that by virtue of their having evolved in parallel over millions of years, the nervous and immune systems currently use the same archetypal principles and strategies to address related challenges in information processing and retrieval. Ultimately, nature is conservative. One need only look at a tree, a river, the airways, or the vascular bed in order to see how a fractal pattern of repetitive dichotomous branching has been used by each, in order to optimize the transport of fluids over large distances [45]. While each system has had to adopt different materials in order to solve the problem, the shape of their solutions is remarkably alike. In the immune and nervous systems, the elements used to produce optimal functional responses are also quite different, but again the solutions have been achieved by comparable strategies. I am certain that these two great systems of information processing, each responding with vastly different kinetics, will prove to be far more integrally interdependent than has been previously recognized. For example, should a swift response by the immune system be required in an overwhelming invasion by microbial pathogens, the immune system may be able to cooperate with the rapidly reacting nervous system to rid the host of the invaders. In this regard, we have shown that the beta-adrenergic hormone epinephrine rapidly increases the traffic of memory T-cells to mucosal sites, presumably representing an immune component of the fight-or-flight response [46]. Neural evolution appears to have as its goal the development of more efficient information processing systems that lead to higher levels of consciousness. However, in modern times, technologic advances in information processing have rapidly outstripped the slower adaptations that can be made by evolution. In order to satisfy his compulsive quest for information, man has recently developed and recruited the aid of computers.(ABSTRACT TRUNCATED AT 400 WORDS)

Association Learning↗

PubMed1980

Impairments in visual discrimination performance and gaze shifts in monkeys with superior colliculus lesions.

Eye movements of monkeys were recorded while they performed a visual discrimination task before and after superior colliculus (SC) lesions or control surgery. The monkeys with SC lesions were impaired in orienting their eyes toward the visual stimuli when they were presented eccentrically 15 degrees to 32 degrees from the center of the display screen, toward which their heads were directed. This impairment in shifting the gaze to eccentric stimuli may account for the concomitant deficit in discriminating between these eccentric stimuli. The eye movement deficit appears to depend on destruction of the deep as well as more superficial layers of the SC and may reflect a disturbance in visual-oculomotor coordination.

Animals↗

PubMed2001

Creative arterial bypass grafting can be performed on the beating heart.

BACKGROUND: To demonstrate that compromise is unnecessary in either the design or performance of beating heart surgery, we report our experience, over 1 year, of total arterial revascularization where composite or creative grafting was utilized. METHODS: We performed 321 off-pump coronary artery bypass operations, of which, 290 (90%) were done with only arterial conduits. The mean number of distal anastomoses was 2.48, with a range of 1 to 5. There were no aortic anastomoses. One hundred eighty-nine patients (65%) were male, and 101 (35%) were female, with a mean age of 67 years. Comorbidities included chronic renal failure (CRF), 21 (7%); diabetes, 92 (32%); obesity, 68 (23%); hypertension, 212 (73%); chronic obstructive pulmonary disease, 189 (65%); cerebral vascular accident (CVA), 39 (13%); smoking, 164 (56%); and hypercholesterolemia, 151 (52%). The mean ejection fraction was 56%, with a range of 21% to 71%. All procedures were performed with external stabilizers with or without vacuum assist. The complete arterial revascularizations included a T-graft (internal thoracic [ITA]/radial arteries [RA]), 130 (45%); a sequential graft (ITA +/- RA), 118 (41%); a U-graft (coronary-coronary graft perfused by the ITA or right gastroepiploic artery), 5 (2%); an I-graft (ITA/RA), 4 (1%); an X-graft (ITA/RA), 2 (12); and a Y-graft (ITA/RA), 31 (10%). RESULTS: The postoperative incidence of atrial fibrillation was 80 of 290 (27%); CVA, 5 of 290 (2%); bleeding resulting in take-back, 5 of 290 (2%); CRF, 8 of 290 (3%); deep sternal infection, 4 of 290 (1%); and readmission (30-day) for angina, 4 of 290 (1%). The observed perioperative (30-day) mortality was 9 of 290 (3.1%), with the STS predicted rate of 3.82%. CONCLUSIONS: Our experience indicates that once the operating surgeon has learned to safely expose the lateral and inferior walls of the heart, the type of conduit and the method of revascularization should be no different than that used with cardiopulmonary bypass. However, we still recommend conventional methods of revascularization (on-pump with saphenous vein conduits) for the ischemic patient.

Aged↗

PubMed1999

Mismatch of classroom furniture and student body dimensions: empirical findings and health implications.

PURPOSE: To examine possible mismatch between the individual body dimensions of students and the classroom furniture they use. METHODS: A total of 74 (37 male and 37 female) sixth-through eighth-grade students in a Michigan school district participated in the study; their ages ranged from 10 years, 11 months to 14 years, 3 months. Anthropometric measurements (including elbow height, shoulder height, upper arm length, knee height, popliteal height, buttock-popliteal length, and stature) were gathered in several physical education classes, each during a single session. In addition, the furniture dimensions were measured for three styles of chairs and three styles of desks prevalent in the students' classrooms. Based on both the information about student body dimensions and furniture dimensions, measures of fit or mismatch were constructed. RESULTS: The data indicate a substantial degree of mismatch between the students' bodily dimensions and the classroom furniture available to them. Fewer than 20% of students can find acceptable chair/desk combinations. Most students are sitting in chairs with seats that are too high or too deep and at desks that are too high. Even after controlling for body stature, girls are less likely to find fitting chairs. CONCLUSIONS: Based on the evidence presented, many sixth through eighth graders must endure seating arrangements in their classrooms that are not conducive to learning.

Adolescent↗

PubMed1995

Early cerebellar lesions impair eyeblink conditioning in developing rats: differential effects of unilateral lesions on postnatal day 10 or 20.

Experiment 1 demonstrated that the ipsilateral cerebellar hemisphere is essential for the acquisition of eyeblink conditioning in infant rats and that cerebellar lesions given on Postnatal Day 10 (PND10) produced deficits in eyeblink conditioning when given to either hemisphere. For both hemispheres, lesions that were restricted to the cerebellar cortex produced less severe deficits than lesions that included the deep nuclei. Experiment 2 showed that the age at which the cerebellar lesions occurred determined whether damage to the contralateral cerebellar hemisphere impaired conditioning. Lesions of either the ipsilateral or contralateral hemisphere that included the deep nuclei disrupted eyeblink conditioning when given on PND10. In contrast, when lesions were given on PND20, ipsilateral lesions that included the deep nuclei abolished conditioning, while the same lesion given to the contralateral hemisphere had no effect.

Aging↗

PubMed1999

Red muscle activation patterns in yellowfin (Thunnus albacares) and skipjack (Katsuwonus pelamis) tunas during steady swimming.

To learn about muscle function in two species of tuna (yellowfin Thunnus albacares and skipjack Katsuwonus pelamis), a series of electromyogram (EMG) electrodes was implanted down the length of the body in the internal red (aerobic) muscle. Additionally, a buckle force transducer was fitted around the deep caudal tendons on the same side of the peduncle as the electrodes. Recordings of muscle activity and caudal tendon forces were made while the fish swam over a range of steady, sustainable cruising speeds in a large water tunnel treadmill. In both species, the onset of red muscle activation proceeds sequentially in a rostro-caudal direction, while the offset (or deactivation) is nearly simultaneous at all sites, so that EMG burst duration decreases towards the tail. Muscle duty cycle at each location remains a constant proportion of the tailbeat period (T), independent of swimming speed, and peak force is registered in the tail tendons just as all ipsilateral muscle deactivates. Mean duty cycles in skipjack are longer than those in yellowfin. In yellowfin red muscle, there is complete segregation of contralateral activity, while in skipjack there is slight overlap. In both species, all internal red muscle on one side is active simultaneously for part of each cycle, lasting 0.18T in yellowfin and 0.11T in skipjack. (Across the distance encompassing the majority of the red muscle mass, 0.35-0.65L, where L is fork length, the duration is 0.25T in both species.) When red muscle activation patterns were compared across a variety of fish species, it became apparent that the EMG patterns grade in a progression that parallels the kinematic spectrum of swimming modes from anguilliform to thunniform. The tuna EMG pattern, underlying the thunniform swimming mode, culminates this progression, exhibiting an activation pattern at the extreme opposite end of the spectrum from the anguilliform mode.

Journal Article↗

PubMed1999

Early experience using duplex ultrasonography in the diagnosis of deep venous thrombosis; a prospective evaluation.

Duplex ultrasound is used in many radiology departments as the first line of investigation for symptomatic deep venous thrombosis. Before changing the practice of our department from venography to duplex ultrasonography, we wanted to assess our ability to identify deep venous thrombosis on ultrasound. Thirty-eight patients were investigated for suspected deep venous thrombosis by venography and duplex ultrasound. The results were compared using venography as the 'gold standard'. Duplex ultrasound correctly identified 13 out of 16 limbs with deep venous thrombosis. Four of the 38 duplex ultrasound examinations (11%) were described as inadequate at the time of examination, and when these are excluded from the analysis a sensitivity of 93 %, and specificity of 80 % are achieved. We conclude that there is a significant learning curve when performing duplex ultrasound of the lower limb, and that change-over from venography to ultrasound should include a period during which both examinations are routinely performed.

Adult↗