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PubMed1995

Investigations of exemplar and decision bound models in large, ill-defined category structures.

Experiments involving large-size, ill-defined categories were conducted to distinguish between the predictions of an exemplar model and linear and quadratic decision bound models. In conditions in which the optimal classification boundary was of a more complex form than the quadratic model, the exemplar model provided significantly better accounts of study participants' data than did the decision bound models, even in situations in which a linear bound would have yielded nearly optimal performance. The results suggest that participants are not predisposed or constrained to use linear or quadratic decision bounds for classifying multidimensional perceptual stimuli and that exemplar models may provide a parsimonious process-level account of the complex types of decision bounds used by experiment participants. The results also suggest some limitations on the complexity of the decision bounds that can be learned, in contrast to the predictions of the exemplar model.

Adult↗

PubMed1987

Age and forgetting rate with pictorial stimuli.

The rate of forgetting standardized line drawings of common objects was assessed in groups of young (M age = 22 years) and older (M age = 70.5 years) subjects. The two groups forgot equal quantities of pictorial stimuli over successive intervals of 10 min, 2 hr, and 48 hr, after being matched for original learning. In contrast, the older subjects showed the expected age decrement in reproduction of geometric designs from memory. These findings indicate that aging does not affect retention of pictures when differences in learning and retrieval abilities are controlled.

Adolescent↗

PubMed2004

Notch signaling in Drosophila long-term memory formation.

Notch (N) is a cell surface receptor that mediates an evolutionarily ancient signaling pathway to control an extraordinarily broad spectrum of cell fates and developmental processes. To gain insights into the functions of N signaling in the adult brain, we examined the involvement of N in Drosophila olfactory learning and memory. Long-term memory (LTM) was disrupted by blocking N signaling in conditional mutants or by acutely induced expression of a dominant-negative N transgene. In contrast, neither learning nor early memory were affected. Furthermore, induced overexpression of a wild-type (normal) N transgene specifically enhanced LTM formation. These experiments demonstrate that N signaling contributes to LTM formation in the Drosophila adult brain.

Animals↗

PubMed2002

Modelling coaching practice: the role of instruction and demonstration.

In this paper, we review the empirical literature pertaining to the effectiveness of instructions and movement demonstrations. Initially, we examine existing theories and approaches that try to explain the process of skill acquisition so as to determine implications of these theories for instructional provision. This is followed by an evaluation of studies in the motor learning literature in which pre-practice information has been manipulated. Explicit learning strategies are contrasted to implicit and discovery learning methods, and current explanations for instructional effects are discussed in terms of such mechanisms as effects-related attentional focus and movement variability. In the final sections, we review data from our own laboratory where pre-practice information has been manipulated during the learning of a novel bimanual coordination task. From these studies, proposals are made to try and explain how pre-practice information works to effect the process of skill acquisition, including the selection and execution of a response and the processing of associated feedback. An important role is given to the existing skills of the learner in understanding the instructions and performing the desired movement. Finally, we suggest some practical implications of this empirical evidence for the teaching of motor skills.

Humans↗

PubMed1997

A predictive model of student satisfaction with the medical school learning environment.

PURPOSE: To examine differences in attitudes toward the medical school learning environment among student subgroups based on gender and race-ethnicity, to identify the most influential predictors of student satisfaction with the learning environment, and to create a model of student satisfaction with the learning environment. METHOD: Three years of survey data (1992-93 to 1994-95) from first-year students at the University of Michigan Medical School were combined. The total sample consisted of 430 respondents, broken into two sets of subgroups: women (n = 171) and men (n = 259), and whites (n = 239) and underrepresented minorities (n = 74). Asian students were removed from analyses when comparisons were made by race-ethnicity, but were included in the analyses for all students and those comparing men and women. Student's t-tests were used to identify differences between gender and racial-ethnic groups in mean responses to seven survey items, and effect sizes were used to characterize the magnitudes and practical significances of the differences. Forward stepwise regression was conducted to determine the best predictive models for each student subgroup and for the total sample; the subgroup models were compared with each other as well as with the total-sample model. RESULTS: Cross-validation of the gender and race-ethnicity models showed that the men's satisfaction and the women's satisfaction were predicted equally well using either subgroup's model, and that the white students' satisfaction and the underrepresented-minority students' satisfaction were predicted equally well using either subgroup's model. Furthermore, the total-sample model, employing a subset of five predictors, was similar in its predictive power to the subgroup models. CONCLUSION: The study's findings suggest that curriculum structure (timely feedback and the promotion of critical thinking) and students' perceptions of the priority faculty place on students' education are prominent predictors of student satisfaction (across all subgroups) with the learning environment. In contrast, students' perceptions of the learning environment as a comfortable place for all gender and racial-ethnic groups, although less prominent predictors of satisfaction, will discriminate among the subgroups.

Consumer Behavior↗

PubMed2000

Professional growth, learning, and the study club.

The imperative for human growth and the need for continuous professional development are related. This article describes some of the practical decisions about forming a study club and finding a leader that promotes professional growth. Thoughts are offered about learning in this context as contrasted to school learning and about the psychology of growth.

Communication↗

PubMed2001

Influence of cholinergic system on motor learning during aging in mice.

Three, 12- and 20-month-old C57Bl6 mice, reared in standard conditions or in an enriched environment, were administered subcutaneously either scopolamine hydrobromide (SIGMA), 0.6 and 1.2 mg kg(-1), or physiological saline 15 min before testing their motor skills (muscular strength, dynamic equilibrium and motor coordination) and motor learning abilities (number of trials needed to reach a learning criterion on a rotorod rotating at 27 revolutions per min). The results demonstrated a lack of correlation between motor skill scores and between motor skill and motor learning scores, suggesting that the rotorod training procedure measures motor learning and not motor skills or is insensitive to changes in motor skills. They also demonstrated that motor skills decreased with age but were insensitive to environmental rearing and to scopolamine. In contrast, the learning scores, which also decreased with age, were very sensitive to scopolamine, particularly in the oldest mice. These results are discussed according to the role of cholinergic system in motor learning during aging.

Aging↗

PubMed1997

Piriform cortex ablations block navigational map learning in homing pigeons.

Young homing pigeons were subjected to ablations of the piriform cortex or left intact and allowed to learn a navigational map. Three months later, control and piriform cortex lesioned pigeons were released from three unfamiliar locations. Control pigeons oriented homeward indicating successful navigational map learning. In contrast, piriform cortex ablated pigeons consistently oriented east, took more time to return home and were more likely to get lost. The results demonstrate that piriform cortex ablations in young homing pigeons disrupt navigational learning. The data support the conclusion that participation of the piriform cortex is necessary for navigational map learning, and its role in navigational learning cannot be substituted for by other telencephalic olfactory processing regions. Further, the results show that the role of olfactory cues in building up the navigational map cannot be replaced by other non olfactory environmental stimuli.

Animals↗

PubMed2000

Changes in functional connectivity in orbitofrontal cortex and basolateral amygdala during learning and reversal training.

Interconnections between orbitofrontal cortex (OFC) and basolateral amygdala (ABL) are critical for encoding and using associative information about the motivational significance of stimuli. Previously, we reported that neurons in OFC and ABL fired selectively to cues during odor discrimination learning and reversal training. Here we conducted an analysis of correlated firing in the cell pairs recorded in the previous study. Correlated firing during the intertrial intervals was compared across task phases during different phases of acquisition and reversal learning. Changes in correlated activity during initial learning and subsequent accurate performance on the discrimination problems closely resembled the changes in odor selectivity in OFC and ABL reported earlier. Increased correlated firing was most pronounced in OFC during accurate go, no-go performance in the postcriterion phase of performance, whereas correlated firing in ABL increased primarily during an earlier phase of learning. In contrast, findings during subsequent reversal training diverged from our earlier report in which odor selectivity diminished in OFC and reversed in ABL. When the reinforcement contingencies of the odors were reversed after the rat had learned the original associations, correlated firing further increased significantly in OFC but remained stable in ABL. This evidence that associative encoding increments with reversal learning in OFC suggests that the original associations, although not expressed as stimulus driven activity, may be maintained within the network as new associations are acquired.

Amygdala↗

PubMed1997

David Hartley's psychobiological associationism and the legacy of Aristotle.

The idea that there are certain "laws" of learning (similarity, contrast, contiguity) can be traced to Aristotle. He maintained that external stimuli cause small movements in the vessels to the dominant heart, the vestiges of which can be linked to one another. Aristotle's laws of learning were incorporated into the writings of Hobbes, Locke, and Berkeley, men who said nothing about the physiological correlates of mental associations. This left the door open for David Hartley to combine mental associationism with the Newtonian idea that sensations can cause minute particle vibrations in the nerves. Hartley's amalgam of psychology, philosophy, and neurology was first presented in 1746, as a "trial balloon" at the end a little-known monograph on a treatment for kidney stones. It was repeated three years later in his better-known Observations on Man. In many ways, modern psychobiological connectionism can be traced back to Hartley's Conjectures of 1746, in which Aristotle's original thoughts were modified with then current ideas about functions of the mind and the nervous system.

Greece↗

PubMed1994

Similarity and discrimination: a selective review and a connectionist model.

The 1st part of this article evaluates the extent to which 2 elemental theories of conditioning, stimulus sampling theory and the Rescorla-Wagner (1972) theory, are able to account for the influence of similarity on discrimination learning. A number of findings are reviewed that are inconsistent with predictions derived from these theories, either in their present form or in various modified forms. The 2nd part of the article is concerned with developing an alternative, configural account for discrimination learning. In contrast to previous configural theories, the present version is set within the framework of a connectionist network.

Animals↗

PubMed2006

Effects of ApoE genotype and mild cognitive impairment on implicit learning.

The goals were to investigate implicit learning in mild cognitive impairment (MCI), and to determine the relations of implicit learning systems to apolipoprotein E (ApoE) genotype in healthy controls. Elderly controls grouped by ApoE status (ApoE-e4 allele carriers versus ApoE-e4 allele non-carriers) and MCI patients participated in the study. Individuals in all three groups completed both contextual cueing and serial reaction time (SRT) tasks. In the former, people learn to use repeated spatial configurations to facilitate search for a target, whereas in the latter, they learn to use subtle sequence regularities to respond more quickly and accurately to a series of events. Results revealed that healthy elderly individuals carrying the ApoE-e4 allele showed contextual cueing deficits compared to those who did not carry the ApoE-e4 allele. Further, elderly controls carrying the ApoE-e4 allele revealed similar amounts of contextual cueing as the MCI group, while the non-carriers performed better. Sequence learning, by contrast, was uninfluenced by either MCI or by ApoE genotype in healthy controls. This study provides further support for the medial temporal lobe dysfunction and relative integrity of fronto-striatal systems in MCI, and indicates the influence of ApoE genotype on implicit learning even in healthy older individuals without cognitive impairment.

Aged↗

PubMed2005

Measures of visual function and time to driving cessation in older adults.

PURPOSE: Older adults may place restrictions on their driving once their visual function has become compromised, presumably in an effort to ensure their safety. It is important to identify the types of visual function loss that lead to driving cessation to better understand the relationship between vision and driving. METHODS: Data were used from the Salisbury Eye Evaluation project, a cohort study of 2520 older adults followed for 8 years with four rounds of data collection. Multiple measures of visual function were objectively assessed and driving information was collected through self-report from subjects or proxies. Cox regression was used to examine whether those with worse baseline and 2-year change scores in acuity, contrast sensitivity, visual fields, and glare sensitivity were more likely to stop driving after baseline after adjusting for demographic and health variables. RESULTS: Those with worse baseline scores in acuity, contrast sensitivity, central or lower peripheral visual fields were more likely to stop driving (trend p values < 0.05). Also, those who experienced 2-year losses in acuity, contrast sensitivity, or lower peripheral visual fields were more likely to stop driving (trend p values < 0.05). With the vision variables entered into the same model, baseline acuity and 2-year acuity loss were no longer statistically significant. Those with worse baseline scores in contrast sensitivity, central and lower peripheral visual fields were more likely to stop driving (trend p values < 0.05), and those who had 2-year losses in contrast sensitivity and lower peripheral visual fields were more likely to stop driving (trend p values < 0.05). Interactions with gender, other drivers in the house, or cognitive impairment were not detected. CONCLUSIONS: We present prospective data that indicate that older adults with worse scores in multiple measures of vision are more likely to stop driving and that contrast sensitivity and visual fields are most associated with driving cessation.

Accidents, Traffic↗

PubMed2006

The striatum and probabilistic implicit sequence learning.

The distinction between implicit (unconscious) and explicit (conscious) learning is controversial. Some argue that explicit learning is dependent on the medial temporal lobes, whereas implicit learning is mediated by the basal ganglia and others propose that all learning is explicit. The purpose of the present study was to investigate the involvement of the basal ganglia in implicit learning by examining learning of a probabilistic sequence of targets, in patients with Parkinson's disease (PD) and controls. Following learning, we assessed participants' awareness of the sequence structure by asking them to generate or withhold sequence consistent responses (process dissociation procedure) and to perform a recognition test in which measures of priming and recognition were obtained concurrently. Although the PD group demonstrated evidence of probabilistic sequence learning in this study, learning was significantly attenuated compared to controls. Residual learning in the PD group was genuinely implicit in nature because (a) PD patients were not able to control the expression of their acquired knowledge, and (b) their knowledge supported subsequent priming of sequence-consistent responses but recognition ratings were at chance. In contrast, following learning controls were capable of above chance recognition indicating that their sequential knowledge was acquired in a more explicit way. The results support the view that (i) the basal ganglia contribute to probabilistic implicit sequence learning (ii) that such learning can occur implicitly without explicit knowledge in PD patients.

Aged↗

PubMed1998

Motor and learning dysfunction during postnatal development in mice defective in dopamine neuronal transmission.

Mice lacking expression of tyrosine hydroxylase (TH), the first and rate-limiting enzyme of the catecholamine biosynthetic pathway, in dopaminergic neuronal cell types were generated by a transgenic rescue approach to clarify the role of dopamine signaling during postnatal development. Introduction of the TH transgene directed by the dopamine beta-hydroxylase gene promoter into TH knockout mice restored noradrenaline and adrenaline synthesis, preventing perinatal lethality and cardiac dysfunction in the knockout mice. Lack of TH expression in the cells that normally express the dopaminergic phenotype resulted in a marked reduction of dopamine accumulation in the tissues, which led to multiple behavioral abnormalities at the juvenile stage. These abnormalities were characterized by a reduction in spontaneous locomotor activity, blockade of methamphetamine-induced hyperactivity, cataleptic behavior, and defects in active avoidance learning. In contrast, development of the pituitary gland as well as production and secretion of the pituitary peptide hormones dependent on hypothalamic dopaminergic control were normally maintained, despite defective dopamine synthesis. These results demonstrate that dopamine neurotransmission is essential for controlling spontaneous and voluntary movement and associative learning during postnatal development through the nigrostriatal and mesocorticolimbic pathways.

Animals↗

PubMed2006

The effects of metabolic stress and vagotomy on emotional learning in an animal model of anxiety.

The aim of the present study is to evaluate the role of the blood glucose (BG) level in emotional learning in the elevated plus maze (EPM), an animal model of anxiety. In Experiment 1, male Wistar rats were submitted to different EPM trial lengths (1- or 5-min). Blood samples were withdrawn before and after the maze exploration, through a polyethylene cannula chronically implanted into the jugular vein. In Experiment 2, the animals received either saline or 2-deoxy-D-glucose, a glucoprivic drug (2-DG, 250 or 500 mg kg(-1)) by i.p. route, 30 min before a 5-min EPM exposure and were retested in the maze (Trial1/Trial2 EPM procedure) 24 h later. In an independent group of rats, blood samples were withdrawn 0, 5, 15, and 30 min after 2-DG administration, through the jugular vein, to determine BG. In Experiment 3, the animals underwent a vagotomy and were tested in a Trial1/Trial2 EPM procedure four weeks later. The results showed that rats exploring the EPM for 5 min displayed increased fear and higher hyperglycemia than those exploring the EPM for 1 min. In addition, rats submitted to 5-min EPM Trial1 length displayed higher level of fear on Trial2, as well as higher percentage of shortening of the %Open arm entries and %Open arm time from Trial1 to Trial2, which characterizes the occurrence of emotional learning. In contrast, rats previously vagotomized or treated with 2-DG (500 mg kg(-1)) showed the same level of fear on both EPM trials and a low percentage of shortening, from Trial1 to Trial2, of the %Open arm entries and %Open arm time, indicating poor emotional learning. The data is discussed regarding the role of glycaemia in emotional learning in the EPM.

Analysis of Variance↗

PubMed2005

Night driving self-restriction: vision function and gender differences.

PURPOSE: The purpose of this study was to evaluate gender differences in the relationship between night driving self-restriction and vision function in an older population. METHODS: Night driving self-restriction patterns (assessed by questionnaire) were examined cross-sectionally in relation to age, gender, health and cognitive status, depression, and vision function in a sample of 900 elders (mean age, 76 years) living in Marin County, California. RESULTS: Of the total sample, 91% of men and 77% of women were current drivers. The mean age of the drivers was 73.3 years (range, 58-96 years). Among current drivers, women had slightly better vision function than men on most measures (low-contrast acuity, contrast sensitivity, low-contrast acuity in glare, low-contrast, low-luminance acuity, and glare recovery) but were twice as likely as men to restrict their driving to daytime. Men showed significant associations with avoidance of night driving on four spatial vision measures (high- and low-contrast acuity, low-contrast, low-luminance acuity, and contrast sensitivity). For women, in addition to these measures, a significant association was seen for low-contrast acuity in glare. Neither men nor women showed significant associations between driving restriction and performance on the other vision measures examined (glare recovery time, attentional field integrity, or stereopsis). The vision measures most predictive of self-restriction were contrast sensitivity for men and low-contrast acuity in glare for women. CONCLUSIONS: Including both cessation and self-restriction, men over age 85 years are 6.6 times more likely than women to be driving at night. For both genders, vision plays a significant role in the self-restriction decision. A higher percentage of men than women continue to drive at night with poor vision. Men's night-driving cessation was associated with contrast sensitivity and depression, whereas women's night-driving cessation was associated with low-contrast acuity in glare as well as age.

Accidents, Traffic↗

PubMed2000

Dopamine deficiency in mice.

Dopamine is the principal neurotransmitter that mediates a wide range of brain functions, including locomotion, emotion, learning, and neuroendocrine modulation. To clarify the role of dopamine during postnatal development, it is useful to have mutant mice genetically deleting dopamine. In this paper, we describe the mice lacking expression of tyrosine hydroxylase (TH), the first and rate-limiting enzyme of catecholamine biosynthetic pathway, in the dopaminergic neuronal type. In these mice, TH expression in noradrenergic and adrenergic cells was restored. Lack of TH expression in dopaminergic neurons resulted in a marked reduction of dopamine accumulation. This led to multiple behavioral abnormalities at the juvenile stage, which were characterized by a reduction in spontaneous locomotor activity, blockade of methamphetamine-induced hyperactivity, cataleptic behavior, and defect in active avoidance learning. In contrast, development of pituitary gland as well as production and secretion of the pituitary peptide hormones dependent on hypothalamic dopaminergic control were normally maintained in spite of the reduced dopamine synthesis. Our findings provide genetic evidence that dopamine is essential for controlling spontaneous and voluntary movement and emotional learning during postnatal development through the nigrostriatal and mesocorticolimbic pathways.

Age Factors↗