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PubMed2006

The influence of different training schedules on the learning of psychomotor skills for endoscopic surgery.

BACKGROUND: Psychomotor skills for endoscopic surgery can be trained with virtual reality simulators. Distributed training is more effective than massed training, but it is unclear whether distributed training over several days is more effective than distributed training within 1 day. This study aimed to determine which of these two options is the most effective for training endoscopic psychomotor skills. METHODS: Students with no endoscopic experience were randomly assigned either to distributed training on 3 consecutive days (group A, n = 10) or distributed training within 1 day (group B, n = 10). For this study the SIMENDO virtual reality simulator for endoscopic skills was used. The training involved 12 repetitions of three different exercises (drop balls, needle manipulation, 30 degree endoscope) in differently distributed training schedules. All the participants performed a posttraining test (posttest) for the trained tasks 7 days after the training. The parameters measured were time, nontarget environment collisions, and instrument path length. RESULTS: There were no significant differences between the groups in the first training session for all the parameters. In the posttest, group A (training over several days) performed 18.7% faster than group B (training on 1 day) (p = 0.013). The collision and path length scores for group A did not differ significantly from the scores for group B. CONCLUSION: The distributed group trained over several days was faster, with the same number of errors and the same instrument path length used. Psychomotor skill training for endoscopic surgery distributed over several days is superior to training on 1 day.

Adult↗
PubMedDate not supplied

Signal transduction and the fate of the R7 photoreceptor in Drosophila.

The sevenless protein tyrosine kinase receptor plays a central role in the pathway of cell fate induction that determines the development of the R7 photoreceptor in the Drosophila eye. In the last year we have learned much about the probable ligand for sevenless and have begun to dissect the signal transduction pathway that relays the information from the sevenless kinase. Studies of the mechanisms governing the specificity of signal transmission and reception suggest that the sevenless signal directs a bipotential cell towards a neuronal rather than a cone cell fate.

Animals↗
PubMed2006

A probabilistic model of gaze imitation and shared attention.

An important component of language acquisition and cognitive learning is gaze imitation. Infants as young as one year of age can follow the gaze of an adult to determine the object the adult is focusing on. The ability to follow gaze is a precursor to shared attention, wherein two or more agents simultaneously focus their attention on a single object in the environment. Shared attention is a necessary skill for many complex, natural forms of learning, including learning based on imitation. This paper presents a probabilistic model of gaze imitation and shared attention that is inspired by Meltzoff and Moore's AIM model for imitation in infants. Our model combines a probabilistic algorithm for estimating gaze vectors with bottom-up saliency maps of visual scenes to produce maximum a posteriori (MAP) estimates of objects being looked at by an observed instructor. We test our model using a robotic system involving a pan-tilt camera head and show that combining saliency maps with gaze estimates leads to greater accuracy than using gaze alone. We additionally show that the system can learn instructor-specific probability distributions over objects, leading to increasing gaze accuracy over successive interactions with the instructor. Our results provide further support for probabilistic models of imitation and suggest new ways of implementing robotic systems that can interact with humans over an extended period of time.

Attention↗
PubMed2006

Neural correlates of response reversal: considering acquisition.

Previous work on response reversal has typically used a single pair of stimuli that serially reverse. This conflation of acquisition and reversal processes has prevented an examination of the functional role of neural systems implicated in response reversal during acquisition despite the relevance of such data in evaluating accounts of response reversal. In the current study, participants encountered 16 independent reversing stimulus pairs in the context of a probabilistic response reversal paradigm. Functional regions of interest identified as involved in response reversal through a contrast used in the previous literature (punished errors made in the reversal phase versus rewarded correct responses), were interrogated across conditions. Consistent with suggestions that middle frontal cortex codes reward, this region showed significantly greater responses to rewarded rather than punished trials irrespective of accuracy or learning phase (acquisition or reversal). Consistent with the suggestion that this coding of the expectation of reinforcement is acquired via input from the amygdala, we observed significant positive connectivity between activity within the amygdala and a region of rostral anterior cingulate cortex highly proximal to this region of middle frontal/mesial prefrontal cortex. In contrast, inferior frontal cortex, anterior cingulate cortex and caudate showed greater responses to punished errors than to the rewarded correct responses. These three regions also showed significant activation to rewarded errors during acquisition, in contrast to positions suggesting that inferior frontal cortex represents punishment or suppresses previously rewarded responses. Moreover, a connectivity analysis with an anterior cingulate cortex seed revealed highly significant positive connectivity among them. The implications of these data for recent accounts of response reversal and of response reversal impairments in specific neuropsychiatric populations are discussed.

Adult↗
PubMed2002

An institutional experience with laparoscopic gastric bypass complications seen in the first year compared with open gastric bypass complications during the same period.

BACKGROUND: Complication rates for laparoscopic bariatric surgery remain in evolution. METHODS: Single institution review of the initial year's experience with laparoscopic gastric bypass compared with open gastric bypass complications for the same period. RESULTS: There were 20 laparoscopic and 52 open gastric bypass procedures. Five laparoscopic patients had major complications. There were 4 anastomotic leaks. Nine open bypass patients had major complications, with 2 leaks. Leak rate was 20% for the laparoscopic group and 4% for the open group. All leaks in both groups led to substantial morbidity. There were two deaths, one in each group. The laparoscopic death was from postleak sepsis. CONCLUSIONS: Gastric bypass, whether done open or laparoscopically, has significant surgical risk. Complication profiles differed between the two groups. Anastomotic leaks were significantly more frequent in the laparoscopic group, probably related to the learning curve. There is a continued need for open surgery in many bariatric patients.

Adult↗
PubMed2000

Outcome analysis of minimally invasive repair of pectus excavatum: review of 251 cases.

BACKGROUND/PURPOSE: Since the first report in 1997 by Dr Nuss of the technique for minimally invasive repair of pectus excavatum (MIRPE), the popularity and demand for this operation has increased dramatically. Many pediatric surgeons became familiarized with MIRPE and have applied it to a large number of patients. Outcomes and complications have not yet been defined. METHODS: A comprehensive survey of APSA members was conducted to review technical problems, complications, and outcomes of this new technique. RESULTS: Of the 74 survey responders, 31 (42%) currently use the MIRPE as their procedure of choice, and 251 cases were reviewed. A total of 74.2% of surgeons relied on direct observation and written documentation to obtain training in MIRPE. Less than 60% used the chest index in the preoperative assessment. A total of 98% used the Walter Lorenz bar for the MIRPE. The most common complication was bar displacement or rotation requiring reoperation (9.2%). Pneumothorax requiring tube thoracostomy was reported in 4.8%. Less common problems included infectious complications (2%), pleural effusion (2%), thoracic outlet obstruction (0.8%), cardiac injury (0.4%), sternal erosion (0.4%), pericarditis (0.4%), and anterior thoracic artery pseudoaneurysm (0.4%). Three patients (1.2%) required early strut removal. Reoperation using the open modified Ravitch approach was performed in 2 patients (0.8%). Most surgeons indicated that teenaged patients (>15 years old) were at higher risk for complications. Thoracoscopy in combination with MIRPE was used by 61% of the surgeons. Overall patient satisfaction was rated as excellent or good (96.5%). CONCLUSIONS: The relatively high incidence of problems with MIRPE is probably related to the learning curve associated with the introduction of this new technique. Awareness of technical details, careful patient selection, use of a stabilizing bar, and thoracoscopy likely will result in decreased complications. Long-term results are yet to be determined. The development of a national registry is of great importance for further outcome analysis of MIRPE.

Funnel Chest↗
PubMed1997

Effects of pregnancy, sucrose, and various low-protein diets on the eating behavior of rats.

To assess the effects of various low-protein diets on the eating behavior of female rats, 280 rats were assigned to one of 20 groups, according to a 5 x 2 x 2 (Protein Level x Pregnancy x Sugar) design. Each rat was offered one of five isocaloric, soy-based diets: 25%, 8%, 4%, 2% or 1% protein diet. The subjects' intakes and weights were recorded daily for 3 weeks. Protein content of the diet, pregnancy, and the presence of dietary sucrose all had significant effects on diet, sucrose, and protein intake. By the third week of the experiment, pregnant rats offered 1%, 2% or 4% protein diets consumed significantly less of their diet than did their nonpregnant controls, whereas pregnant rats in the 25% protein group consumed significantly more of their diet than did nonpregnant controls. The eating behavior of the rats offered the 8% protein diet was most affected by the presence of dietary sucrose. Pregnant rats in the 8% protein group consumed less of their diet than did nonpregnant controls when sucrose was also offered, but they consumed more of their diet than did nonpregnant controls when sucrose was not offered. A learned food aversion is probably the best explanation for the severe reduction of diet intake observed in pregnant rats in all of the 1%, 2%, and 4% protein groups, as well as in pregnant rats offered the 8% protein diet and sucrose.

Animals↗
PubMed2003

A model for tool-use traditions in primates: implications for the coevolution of culture and cognition.

Inspired by the demonstration that tool-use variants among wild chimpanzees and orangutans qualify as traditions (or cultures), we developed a formal model to predict the incidence of these acquired specializations among wild primates and to examine the evolution of their underlying abilities. We assumed that the acquisition of the skill by an individual in a social unit is crucially controlled by three main factors, namely probability of innovation, probability of socially biased learning, and the prevailing social conditions (sociability, or number of potential experts at close proximity). The model reconfirms the restriction of customary tool use in wild primates to the most intelligent radiation, great apes; the greater incidence of tool use in more sociable populations of orangutans and chimpanzees; and tendencies toward tool manufacture among the most sociable monkeys. However, it also indicates that sociable gregariousness is far more likely to produce the maintenance of invented skills in a population than solitary life, where the mother is the only accessible expert. We therefore used the model to explore the evolution of the three key parameters. The most likely evolutionary scenario is that where complex skills contribute to fitness, sociability and/or the capacity for socially biased learning increase, whereas innovative abilities (i.e., intelligence) follow indirectly. We suggest that the evolution of high intelligence will often be a byproduct of selection on abilities for socially biased learning that are needed to acquire important skills, and hence that high intelligence should be most common in sociable rather than solitary organisms. Evidence for increased sociability during hominin evolution is consistent with this new hypothesis.

Animals↗
PubMed1999

Repressed memories. When are they real? How are they false?

The precise mechanisms by which such false memories are constructed awaits further research. Much is left to learn about the degree of confidence and the characteristics of false memories created in these ways. We have more to learn about the types of individuals who are particularly susceptible to these forms of suggestion, and conversely, who is resistant. As we are learning more, it is probably important to heed the cautionary tale in the data already obtained; mental health professionals, interviewers, and others need to know how much they can potentially influence participants in research, clinical, and forensic contexts and take care to avoid that influence when it might be harmful. Periodic re-reading of Shakespeare's A Midsummer Night's Dream, with a small substitution (change "poet" to "therapist" or to "biased interviewer"), might help keep these important ideas in mind, reminding us how hard it can sometimes be to distinguish a bush from an imagined bear: The poet's eye, in fine fanciful rolling, Doth glance from heaven to earth, from earth to heaven; And as imagination bodies forth The forms of things unknown, the poet's pen Turns them to shapes and gives to airy nothing A local habitation and a name. Such tricks hath strong imagination, that if it would but apprehend some joy, it comprehends some bringer of that joy; Or in the night, imagining some fear, How easy is a bush supposed a bear!

Adolescent↗
PubMed2002

Consequence of feedback-based learning of an effective hand rim wheelchair force production on mechanical efficiency.

OBJECTIVE: Investigation of the effect of visual feedback on effective hand rim wheelchair force production and the subsequent effect on gross mechanical efficiency. DESIGN: Ten subjects in an experimental group and 10 subjects in a control group practised three weeks (3.wk(-1), i.e., a pre-test and 8 trials) on a computer-controlled wheelchair ergometer. Every trial consisted of two blocks of 4 min at 0.15 and 0.25 W.kg(-1) at 1.11 m.s(-1). On three trials an additional block at 0.40 W.kg(-1) was performed. The experimental group practised with and the control group practised without visual feedback on the effectiveness of force production. BACKGROUND: In mechanical terms, the low gross mechanical efficiency of hand rim wheelchair propulsion may be the result of ineffective force production. METHODS: During all trials oxygen uptake, power output, forces and torque on the hand rims were measured. RESULTS: In comparison with the control group, the experimental group at trial 8 had a significantly more effective force production compared to the control group (90-97% vs. 79-83%, respectively), but showed a significantly lower mechanical efficiency (5.5-8.5% vs. 5.9-9.9%, respectively). CONCLUSION: Findings indicate that the most effective force production from a mechanical point of view is not necessarily the most efficient way--in terms of energy cost-- from a biological point of view and that force direction is based on an optimization of cost and effect. RELEVANCE: Learning a more effective force production by visual feedback is not useful for increasing the mechanical efficiency of hand rim wheelchair propulsion.

Adult↗
PubMed1999

Alcohol and visual performance.

1. The authors examined the effect of acute alcohol consumption on a set of visual tasks: visual short term memory, depth perception, and attention. 2. In a repeated measurement design, thirteen subjects performed the tasks once sober and once intoxicated with 0.8 g/kg body weight pure ethanol in orange juice (33% alcohol). Subjects underwent a neuropsychological (Benton test) and a psychophysical test (vernier discrimination) both assessing visual short term memory, the test d2 as a measure of attention and concentration, and a psychophysical depth perception task. 3. Subjects demonstrated significant alcohol-related impairments in depth perception and in visual short term memory as assessed by the vernier discrimination task. However, the neuropsychological Benton test and test d2 failed to reveal alcohol-related changes in performance-probably due to superimposed learning effects. Performance was neither correlated with blood alcohol levels (BAL) nor perceived intoxication. Even though the current BAL was known to the subjects, only half of them demonstrated a close correlation between BAL and perceived intoxication.

Adult↗
PubMed1997

Nervous diseases and Kampo (Japanese herbal) medicine: a new paradigm of therapy against intractable nervous diseases.

Doctors who learned exclusively western medicine probably understand a priori Kampo (Japanese herbal) medicine merely as a kind of folk medicine which is not so effective and only a supplementary therapy to western medicine. We have been performing experiments on the mechanism of epileptogenesis mainly at the cellular level for a long time. During the research process, we unexpectedly encountered Kampo (Japanese herbal) medicine, and also performed research on the mechanism of action of a herbal mixture prescription, saiko-keishi-to-ka-shakuyaku (SK, TJ-960). Recently we discovered that SK acts to induce the best functional state of neurons and consequently intractable nervous symptoms disappear. SK has protective effects against neuron damage, normalizing effects on developmental defects of El mouse neurons, complete preventive effects on stress-induced increased c-fos and HSP 72 expression, complete suppression effects on the Reilly syndrome, complete normalizing effects on expression of the seizure-related gene, PTZ-17, and also, surprisingly, complete suppression effects on amyloid beta protein-induced neuron death. Such wide ranging effects which are preferable to functional maintenance and development of neurons can not be obtained by pure chemical drugs. These findings suggest that we should effectively use such ancient herbal prescriptions which show excellent preventive effects against neuron damage, enforcing action on natural healing forces and even regulatory action against adverse expression of genes, at least to prevent intractable nervous diseases, such as epilepsy, Alzheimer's disease and developmental defects of neurons during pregnancy and after birth. We should also create a future medicine, the 'third medicine', which is situated in a higher dimension than that of contemporary oriental and western medicines. For this purpose, it is necessary to perform research on the mechanism of action of Kampo (Japanese herbal) medicine.

Animals↗
PubMed1999

Properties of acetylcholine receptor ion channels in the acutely dissociated neurons of the marginal division in the rat striatum.

Cell-attached mode of patch clamp technique was employed to investigate the properties of acetylcholine (ACh)-induced ion channels in acutely dissociated neurons from the marginal division (MrD) of rat striatum. Two types of conductance states (25 pS and 60 pS) were recorded. The 25 pS channel (more than 80%) was the main type in the neurons of MrD and was described here. The amplitudes of inward currents increased with hyperpolorization and the reversing potential was about 0 mV. Both single short opening and long burst openings were observed in MrD neurons. Two-time constants of these two kinds of ion channels are 0.29 ms, 1.84 ms and 1.96 ms, 18.24 ms, respectively. Average close time can be fitted with two exponential functions, the two time constants are 1.7 ms and 54 ms. Probability of channel opening is about 0.012 and no voltage-dependence was found. The properties of reversing potential, voltage-independence and the form of agonist to the ion channels indicated that the recorded channel currents flow through AChR channels. The mAChR is involved in slow synaptic transmission and Ach can not induce the opening of mAChR ion channel. The binding site of ACh to AChR and the nAChR ion channel are the same protein, ACh can only activate nAChR ion channel directly. Therefore, the recorded ion channels in the present study are nAChR ion channels. The results suggest that nAChR ion channels exist in the neurons of MrD and the MrD probably is involved in learning and memory mechanism of the brain.

Acetylcholine↗
PubMed1997

Cholecystokinin receptors mediate the development of a preference for the mother by newly born lambs.

The aim of this study was to investigate the effect of selective cholecystokinin (CCK) antagonists on the development of a preference for the mother by newly born lambs. At birth lambs received an injection of the CCK-A antagonist devazepide (0.01 or 0.1 mg/kg), the CCK-B antagonist PD135158 (0.01 or 0.1 mg/kg), or saline for the controls (1 ml/kg). No major side effects were observed in the first 4 postnatal hours except that lambs receiving PD135158 displayed more exploratory behavior towards the maternal body than lambs from the other groups. When tested in a 2-choice test situation at 24 hr of age, lambs treated with PD135158 or saline spent significantly more time near their dams than near the alien ewes, whereas lambs treated with devazepide did not show any discrimination. The effect of devazepide persisted at 48 hr of age. The use of a CCK-A antagonist, but not a CCK-B antagonist, was concluded to prevent the formation of a preferential relationship between the lamb and its mother, most probably by impairing neonatal learning.

Animals↗
PubMed1998

Familiarity breeds differentiation: a subjective-likelihood approach to the effects of experience in recognition memory.

With repeated exposure, people become better at identifying presented items and better at rejecting items that have not been presented. This differentiation effect is captured in a model consisting of item detectors that learn estimates of conditional probabilities of item features. The model is used to account for a number of findings in the recognition memory literature, including (a) the basic differentiation effect (strength-mirror effect), (b) the fact that adding items to a list reduces recognition accuracy (list-length effect) but extra study of some items does not reduce recognition accuracy for other items (null list-strength effect), (c) nonlinear effects of strengthening items on false recognition of similar distractors, (d) a number of different kinds of mirror effects, (e) appropriate z-ROC curves, and (f) one type of deviation from optimality exhibited in recognition experiments.

Humans↗
PubMed2006

SSL: a theory of how people learn to select strategies.

The assumption that people possess a repertoire of strategies to solve the inference problems they face has been raised repeatedly. However, a computational model specifying how people select strategies from their repertoire is still lacking. The proposed strategy selection learning (SSL) theory predicts a strategy selection process on the basis of reinforcement learning. The theory assumes that individuals develop subjective expectations for the strategies they have and select strategies proportional to their expectations, which are then updated on the basis of subsequent experience. The learning assumption was supported in 4 experimental studies. Participants substantially improved their inferences through feedback. In all 4 studies, the best-performing strategy from the participants' repertoires most accurately predicted the inferences after sufficient learning opportunities. When testing SSL against 3 models representing extensions of SSL and against an exemplar model assuming a memory-based inference process, the authors found that SSL predicted the inferences most accurately.

Adult↗
PubMed2003

Pure perceptual-based sequence learning.

Learning a sequence of target locations when the sequence is uncorrelated with a sequence of responses and target location is not the response dimension (pure perceptual-based sequence learning) was examined. Using probabilistic sequences of target locations, the author shows that such learning can be implicit, is unaffected by distance between target locations, and is mostly limited to first-order transition probabilities. Moreover, the mechanism underlying learning affords processing of information at anticipated target locations and appears to be attention based. Implications for hypotheses of implicit sequence learning are discussed.

Adolescent↗