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PubMed2005

Social learning in noncolonial insects?

Social-information use has generated great interest lately and has been shown to have important implications for the ecology and evolution of species. Learning about predators or predation risk from others may provide low-cost life-saving information and would be expected to have adaptive payoffs in any species where conspecifics are observable and behave differently under predation risk. Yet, social learning and social-information use in general have been largely restricted to vertebrates. Here, we show that crickets adapt their predator-avoidance behavior after having observed the behavior of knowledgeable others and maintain these behavioral changes lastingly after demonstrators are gone. These results point toward social learning, a contingency never shown before in noncolonial insects. We show that these long-lasting changes cannot instead be attributed to long re-emergence times, long-lasting effects of alarm pheromones, or residual odor cues. Our findings imply that social learning is likely much more phylogenetically widespread than currently acknowledged and that reliance on social information is determined by ecological rather than taxonomic constrains, and they question the generally held assumption that social learning is restricted to large-brained animals assumed to possess superior cognitive abilities.

Analysis of Variance↗

PubMed1992

A double-blind comparison of the effects of temazepam and triazolam on residual, daytime performance in elderly insomniacs.

Benzodiazepine hypnotic medications are widely prescribed for elderly patients, but there is a paucity of information available concerning the residual cognitive and psychomotor (the morning-after) effects of these drugs. We compared two commonly used hypnotics--temazepam and triazolam--in a double-blind, placebo-controlled, single-dose study with community-dwelling healthy elderly with a DSM-III-R diagnosis of primary insomnia. Forty-five subjects over the age of 65 (mean age 72.23, SD = 4.44) qualified for the study. Subjects were randomly assigned to one of five treatment groups (placebo, triazolam 0.125 mg., triazolam 0.25 mg., temazepam 15 mg., and temazepam 30 mg.). Neuropsychological testing was completed at baseline and 12-14 hours after the dosing. Patients were evaluated with a variety of tests that measured attention, concentration, motor speed, immediate memory, and learning of new information. Separate repeated measured analyses of variance were performed to assess the significant changes among the five treatment groups. We found improved performance or no change in all the measures for all medication groups except for impairment of performance on a serial learning task for both high-dose medication groups. The significance of these results and the need for further research in elderly insomniacs is discussed.

Aged↗

PubMed2001

Retrograde amnesia after hippocampal damage: recent vs. remote memories in two tasks.

We review evidence from experiments conducted in our laboratory on retrograde amnesia in rats with damage to the hippocampal formation. In a new experiment reported here, we show that N-methyl-D-aspartate (NMDA)-induced hippocampal damage produced retrograde amnesia for both hidden platform and two-choice visible platform discriminations in the Morris water task. For both problems there was a significant trend for longer training-surgery intervals to be associated with worse retention performance. Little support is offered by our work for the concept that there is a process involving hippocampal-dependent consolidation of memories in extrahippocampal permanent storage sites. Long-term memory consolidation may take place within the hippocampus. The hippocampus may be involved permanently in storage and/or retrieval of a variety of relational and nonrelational memories if it was intact at the time of learning, even involving information which is definitely not affected in anterograde amnesia after hippocampal damage.

Amnesia, Retrograde↗

PubMed2001

Applying learning theories to develop teaching strategies for the critical care nurse. Don't limit yourself to the formal classroom lecture.

Learning, as defined by Alspach, is "a change in cognitive, psychomotor, and/or affective behaviors." The teaching strategies reviewed in this article have focused on ones that can affect all three learner behaviors if carefully planned and executed by the instructor. It is also key to provide the content in a manner that will appeal to the autonomy and self-direction of the adult learner, keeping in mind the importance of relating new information to previously learned material. Realizing that learners have different learning styles, the instructor also should assess learning styles and vary teaching methods accordingly. Incorporating some of the learner assessments and teaching strategies discussed here can be a change for both the learner and instructor, but it is consistent with modern learning theory where the focus is on the learner.

Adult↗

PubMedDate not supplied

Effects of entorhinal cortex lesions on sensory integration and spatial learning.

BACKGROUND: The entorhinal cortex provides sensory information to the hippocampus for memory and learning. Damage to the entorhinal cortex is common in patients who experience traumatic brain injury, stroke, and Alzheimer's disease. Entorhinal damage is assumed to interfere with sensory integration; however, substantive knowledge of behavioral patterns is lacking. OBJECTIVES: To describe specific behavioral deficits associated with entorhinal cortex injury related to special senses identification, sensory integration, and spatial learning. METHOD: Adult male rats received bilateral entorhinal cortex damage (n = 19) or sham surgery (n = 11) with a subset randomized to participate in special senses identification, exploration, and sensory integration testing. Spatial learning was examined using a water maze. RESULTS: Lesion and control animals were similar in special senses identification testing. Sensory integration was markedly impaired in lesion animals over 3 days for all integration tasks; however, travel deficit persisted for 4 days. By day 5 sensory integration ability was equal. Lesion animals were significantly impaired across all days of spatial learning for swim time (p = .0001) and directional heading error (p = .03). Control animals exposed to sensory testing demonstrated significantly more efficient learning (p = .005) on swim days 2 and 3 versus control animals not exposed to sensory testing. CONCLUSIONS: Early and prolonged behavioral changes are evident following entorhinal cortex damage including sensory integration deficits and persistent spatial learning impairment.

Alzheimer Disease↗

PubMed1985

Sex chromosome variations in school-age children.

Current evidence suggests that some school-age children are born with a sex chromosome variation. Large chromosome surveys of newborns indicate that 0.5% to 0.6% have chromosome errors, with sex chromosome variations accounting for 35% of them. The four most frequently occurring sex chromosome variations are Turner Syndrome (45,X), Klinefelter Syndrome (47,XXY), Polysomy X or Triple X (47,XXX), and Polysomy Y or XYY (47,XYY). Though many individuals with sex chromosome variations can live functionally normal lives, others may experience developmental, physical, psychological, behavioral, and learning impairments. New information has dispelled myths and biases previously associated with these disorders. By becoming knowledgeable about sex chromosome variations and their effects upon children, school health personnel can assist affected children, their families, and teachers.

Adolescent↗

PubMedDate not supplied

Auditory pathway encoding and neural plasticity in children with learning problems.

An inability to process auditory information, especially speech, characterizes many children with learning and attention problems. Our working hypothesis is that these speech-sound perception problems arise, at least in some cases, from faulty representation of the speech signal in central auditory centers. Preconscious neurophysiologic representation of sound structure by central auditory pathway neurons can be reflected by subcortical and cortical aggregate neural responses. These neurophysiologic responses can be modified by perceptual learning. Our research has shown that some children with learning problems demonstrate abnormal perception and neural representation of certain speech sounds. Differences between normal and learning-impaired groups can be attributable to aspects of neural synchrony that are reflected in aggregate neural responses. Deficiencies in neural synchrony in these children are apparent in subcortical (as well as cortical) representations of speech-sound structure, and these timing deficits are related to performance on speech-sound perception and learning measures. Moreover, impaired perception and neurophysiologic encoding of speech sounds can be improved with cue enhancement and can be modified by perceptual learning associated with auditory training.

Child↗

PubMed2002

Iterative method for learning skills as an efficient outpatient teacher.

BACKGROUND: We sought to identity the choices and the methods used by ambulatory teachers in a qualitative study, using teacher-intern-patient role plays to improve ambulatory teaching. METHODS: We used repeated performances of a scripted role play; during each iteration, field notes were taken by the authors. Insights garnered at each iteration were incorporated into the next version of the role play. After 9 iterations, no further insights into outpatient teaching were forthcoming, and our observations were included into a qualitative study. RESULTS: The sequence of steps and major choices to be made in an outpatient teaching encounter were delineated. The goals of the initial opening phase were defined as setting a learning climate, gathering information about the case, and assessing the learner's level of knowledge. Alternatives posed for setting up the second phase of the interaction with the patient included the choice of being a role model or being a "coach." Three-way conversations between patient, learner, and teacher were described in this phase of the encounter. In the final or summary phase of the encounter, we described the choices between giving a "general rule" for learning, and/or exploring higher-level issues, such as patient-doctor communication skills, medical ethics, or feedback for the learner. CONCLUSIONS: The sequence of steps involved in an outpatient teaching encounter, were defined, and the major choices to be made in the encounter were described.

Ambulatory Care↗

PubMedDate not supplied

The effects of mild diastolic hypertension on the results of tests of cognitive function in adults 22 to 59 years of age.

OBJECTIVE: To test the hypothesis that mild diastolic hypertension (90 to 104 mm Hg) may induce asymptomatic impairment of cognitive function. DESIGN: Cross-sectional. SETTING: Community participants recruited to a university-based ambulatory care center. PARTICIPANTS: Three hundred twelve men and women with untreated essential hypertension and 47 normotensive subjects, 22 to 59 years of age. MEASUREMENTS AND MAIN RESULTS: Cognitive function tests measured reaction time to and accuracy in interpreting predetermined visual stimuli, the ability to acquire, reproduce, and change a set of arbitrary stimulus-response associations, and memory and learning of verbal information. These tests were selected to detect subtle differences in performances as opposed to differentiating neurologically normal persons from brain-damaged persons. After controlling for age, gender, and education, results showed that there was no significant difference between the normotensive and hypertensive subjects in two measures of reaction time to and four measures of accuracy in interpreting predetermined visual stimuli, in the measure of arbitrary stimulus-response associations, or in seven memory and learning variables. Although confidence intervals for the differences between means were wide, clinically significant differences were not likely to be present. Younger age was associated with faster reaction times, fewer errors, and better performance on memory and learning tasks, independent of diastolic blood pressure. CONCLUSIONS: The few detectable effects of untreated mild hypertension on cognitive function reported in the literature may be due to chance and are of questionable clinical significance.

Adult↗

PubMedDate not supplied

Designing web-based education courses for nurses.

Maintaining lifelong learning in health care with its diversity and pressure on resources requires creative solutions to meet the needs of learners and organisations. As technology has evolved, web-based learning has been viewed as one solution. This article discusses the increasing use of online courses and activities in nursing education. It concludes that further research into what nurses want from web-based learning may better inform course design and the development of other web-based educational resources.

Attitude of Health Personnel↗

PubMed2001

Osteotomies of the fifth metatarsal.

Although the literature is limited primarily to retrospective small case series of the operative technique of fifth metatarsal osteotomies with a short follow-up, some important information can be learned. Stabilization of the osteotomy with Kirschner wire fixation appears to decrease dorsal displacement of the distal fragment and distal osteotomies; this leads to decreased incidence of transfer metatarsalgia. Kirschner wire fixation is advocated. The proximal chevron osteotomy of the fifth metatarsal, although stable, has a 20% delayed union rate, most likely resulting from the unique vascular anatomy in this region. The radiographic and clinical results appear to be compatible between distal and proximal osteotomies. Based on this information, primary use of a proximal osteotomy technique is not recommended. The oblique diaphyseal osteotomy technique requires an incision for the osteotomy as well as a distal incision at the metatarsophalangeal joint for correction of this joint. Hardware removal was performed in most patients, and the complications included two cases of delayed union. Time to healing was reported to be 8 weeks, 1.5 times the reported time to healing in distal chevron osteotomies. A significant radiographic correction was noted with the oblique diaphyseal osteotomy; however, radiographic measurements can be altered with foot position and lack of x-ray standardization and technique. Kitaoka et al found no correlation with the degree of radiographic correction and post-operative clinical symptoms. The authors agree with Kitaoka et al that the oblique diaphyseal osteotomy should be reserved for patients who fail an initial distal osteotomy technique. Distal oblique osteotomies appear to have less stability and more complications with malunion, transfer metatarsalgia, and delayed union and should be abandoned for a more stable chevron technique. The distal chevron osteotomy has a small incidence of transfer metatarsalgia; however, it appears to improve the clinical radiographic appearance of [table: see text] the foot with a shortened time to healing (4 to 6 weeks). A biplanar technique can be employed with a distal chevron osteotomy to improve plantar callosity symptoms. More studies are needed to examine critically patient outcomes with uniplanar and biplanar techniques using the distal chevron osteotomy.

Foot Deformities↗

PubMed2006

Insight and strategy in multiple-cue learning.

In multiple-cue learning (also known as probabilistic category learning) people acquire information about cue-outcome relations and combine these into predictions or judgments. Previous researchers claimed that people can achieve high levels of performance without explicit knowledge of the task structure or insight into their own judgment policies. It has also been argued that people use a variety of suboptimal strategies to solve such tasks. In three experiments the authors reexamined these conclusions by introducing novel measures of task knowledge and self-insight and using "rolling regression" methods to analyze individual learning. Participants successfully learned a four-cue probabilistic environment and showed accurate knowledge of both the task structure and their own judgment processes. Learning analyses suggested that the apparent use of suboptimal strategies emerges from the incremental tracking of statistical contingencies in the environment.

Analysis of Variance↗

PubMed2002

Cortical representation of auditory space: information-bearing features of spike patterns.

Previous studies have demonstrated that the spike patterns of cortical neurons vary systematically as a function of sound-source location such that the response of a single neuron can signal the location of a sound source throughout 360 degrees of azimuth. The present study examined specific features of spike patterns that might transmit information related to sound-source location. Analysis was based on responses of well-isolated single units recorded from cortical area A2 in alpha-chloralose-anesthetized cats. Stimuli were 80-ms noise bursts presented from loudspeakers in the horizontal plane; source azimuths ranged through 360 degrees in 20 degrees steps. Spike patterns were averaged across samples of eight trials. A competitive artificial neural network (ANN) identified sound-source locations by recognizing spike patterns; the ANN was trained using the learning vector quantization learning rule. The information about stimulus location that was transmitted by spike patterns was computed from joint stimulus-response probability matrices. Spike patterns were manipulated in various ways to isolate particular features. Full-spike patterns, which contained all spike-count information and spike timing with 100-micros precision, transmitted the most stimulus-related information. Transmitted information was sensitive to disruption of spike timing on a scale of more than approximately 4 ms and was reduced by an average of approximately 35% when spike-timing information was obliterated entirely. In a condition in which all but the first spike in each pattern were eliminated, transmitted information decreased by an average of only approximately 11%. In many cases, that condition showed essentially no loss of transmitted information. Three unidimensional features were extracted from spike patterns. Of those features, spike latency transmitted approximately 60% more information than that transmitted either by spike count or by a measure of latency dispersion. Information transmission by spike patterns recorded on single trials was substantially reduced compared with the information transmitted by averages of eight trials. In a comparison of averaged and nonaveraged responses, however, the information transmitted by latencies was reduced by only approximately 29%, whereas information transmitted by spike counts was reduced by 79%. Spike counts clearly are sensitive to sound-source location and could transmit information about sound-source locations. Nevertheless, the present results demonstrate that the timing of the first poststimulus spike carries a substantial amount, probably the majority, of the location-related information present in spike patterns. The results indicate that any complete model of the cortical representation of auditory space must incorporate the temporal characteristics of neuronal response patterns.

Action Potentials↗

PubMed1975

Role of interference in retention by rats with hippocampal lesions.

Involvement of the hippocampus in memory was studied in the rat by employing a retention task with and without interpolated activity. Rats with extensive damage to hippocampus were able to relearn a preoperatively acquired single-alternation task with savings and to perform the single alternation with relatively long delays at a level similar to that of control subjects. However, hippocampals were more affected than normals by an interpolated activity that interferes with retention. The finding of normal retention combined with increased susceptibility to interference supports the view that the memory impairment in subjects with damage to hippocampus may be due to an excess of interference among stored information.

Animals↗

PubMed1968

Serial-choice reaction time: inadequacies of the information hypothesis.

The results of an experiment on serial-choice reaction time, specifically designed as a critical test of the Information Hypothesis, lead to rejection of the hypothesis; information is found to be neither a necessary nor a sufficient condition to account for the data. Where previously information had been interpreted as a determinant of reaction time, it was usually confounded with the probability of nonrepetition of a signal. Thus, to the extent that this confounding is present in previous experiments, the inference attributing an increase in reaction time to an increase in information is logically invalid.

Discrimination Learning↗

PubMed2000

A model of invariant object recognition in the visual system: learning rules, activation functions, lateral inhibition, and information-based performance measures.

VisNet2 is a model to investigate some aspects of invariant visual object recognition in the primate visual system. It is a four-layer feedforward network with convergence to each part of a layer from a small region of the preceding layer, with competition between the neurons within a layer and with a trace learning rule to help it learn transform invariance. The trace rule is a modified Hebbian rule, which modifies synaptic weights according to both the current firing rates and the firing rates to recently seen stimuli. This enables neurons to learn to respond similarly to the gradually transforming inputs it receives, which over the short term are likely to be about the same object, given the statistics of normal visual inputs. First, we introduce for VisNet2 both single-neuron and multiple-neuron information-theoretic measures of its ability to respond to transformed stimuli. Second, using these measures, we show that quantitatively resetting the trace between stimuli is not necessary for good performance. Third, it is shown that the sigmoid activation functions used in VisNet2, which allow the sparseness of the representation to be controlled, allow good performance when using sparse distributed representations. Fourth, it is shown that VisNet2 operates well with medium-range lateral inhibition with a radius in the same order of size as the region of the preceding layer from which neurons receive inputs. Fifth, in an investigation of different learning rules for learning transform invariance, it is shown that VisNet2 operates better with a trace rule that incorporates in the trace only activity from the preceding presentations of a given stimulus, with no contribution to the trace from the current presentation, and that this is related to temporal difference learning.

Algorithms↗

PubMed1984

Current status of the neuromaturational examination as an index of learning disability.

To further define the role of the neuromaturational examination in determining the presence of learning problems, we examined 104 boys, ages 9.5 to 14.1 years, representing three populations of school children: normal (32 boys), gifted (37), and learning disabled (35). Information concerning each child's behavior and development was obtained through a parent questionnaire; cognitive ability and academic achievement were measured by the Wechsler Intelligence Scales for Children (revised) and Woodcock -Johnson Psychoeducational Battery, respectively. Significant relationships emerged between the number of neuromaturational signs and data group membership (LD greater than N greater than G,P less than 0.05). The number of neuromaturational signs decreased with age for normal (P less than 0.05) and gifted (P less than 0.05) children, but not for the learning-disabled group. Tasks that differentiated the normal and learning disabled were entered into a stepwise discriminant analysis, with a resulting classification accuracy of 93.1% and 100% for the normal and learning-disabled boys, respectively. Analysis of covariance indicated that differences in performance of the three groups may reflect IQ differences among the populations. Learning disabled boys were more likely to exhibit synkinesis than normal boys, but gifted boys did not differ from the learning disabled in the frequency of synkinesis. Our data indicate that, although a composite set of neuromaturational tasks can discriminate normal and learning-disabled boys with a high level of accuracy, caution is urged because the findings may be more related to overall intelligence than to a specific learning disability.

Adolescent↗

PubMedDate not supplied

[Recall and reproduction of words: age-dependent activation of context information in recalling episodic memory contents].

Older people tend to have more problems with the retrieval of episodic memory contents than younger people. One hypothesis to explain this phenomenon refers to age deficits in activating specific pieces of contextual information concerning the learning episode. This hypothesis was submitted to an experimental test for 60 old (about 70 years) and 60 young (about 25 years) adults using the recognition failure paradigm. In this paradigm memory performance is assessed by a cued recall test as well as by an unexpected recognition test. The amount of recognition failure served as the central dependent variable; the length of the retention interval and a strategy instruction (given vs not given) were manipulated as independent variables. Various predictions were derived from the central hypothesis and from typical findings in the literature. They are tested by means of statistical hypotheses on planned a priori contrasts. On the whole, the results confirm the hypothesis concerning age deficits in activating context information during retrieval. Implications for models of gerontological changes in episodic memory are discussed within the framework of Tulving's Synergistic Ecphory model.

Adult↗