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PubMed1986

Sex differences in appetitive learning of mice.

Learning abilities of male and female ddY mice were compared in two appetitive tasks (a lever-press task and an 8-arm radial maze task), and two avoidance tasks (a shuttle box task and a light-dark discrimination T-maze task). In the two types of appetitive learning, male mice were significantly superior to female mice. Sex differences were particularly apparent in the acquisition process. In contrast, there was no significant sex difference in learning of the two avoidance tasks. A sex difference in appetitive learning was not found in juvenile mice prior to sexual maturation, and the mice which had established a lever-press response as juveniles did not show any significant difference in the performance level when tested as adults. Thus, a sex difference appeared only in the acquisition stage of adult mice. These results suggest that there exists a sex difference in motivation level for hunting food but not for feeding, and that it causes a sex difference in appetitive learning.

Aging↗

PubMed1993

Visual discrimination impairments following lesions of the superior temporal sulcus are not specific for facial stimuli.

Six rhesus monkeys took part in an experiment on visual learning. In three of the monkeys the part of the superior temporal sulcus in which many of the cells respond selectively to some aspect of faces was removed, while the remaining three animals served as unoperated controls. In Experiment 1 they learned a series of two-choice visual discriminations between patterns. The animals with lesions of the superior temporal sulcus were markedly impaired. The discriminations were of two types: in the first, the discriminanda differed in shape (e.g. Y and 3), while in the second they differed only in their orientation (e.g. ). Unlike animals with lesions to the neighbouring inferior temporal cortex who are impaired on shape but not orientation discriminations, animals with lesions of the superior temporal sulcus were equally impaired on both types of discrimination. In Experiment 2 the same six animals learned a series of discriminations between discriminanda which consisted of photographs of pairs of eyes. Each discrimination was between a set of eyes which looked directly at the viewer and a set in which the gaze was laterally averted to varying degrees. Again, animals with lesions of the superior temporal sulcus showed a marked impairment. We conclude that this impairment may be a general impairment in two-choice visual discrimination learning, rather than a selective impairment in discrimination of eye gaze. This result warns against a simple interpretation of the function of this area as a "face area", concerned only, or chiefly, with the perception and significance of parts of the body, notably faces, and their movements.

Animals↗

PubMed1986

Acquisition of semantic role by language-disordered children: differences between production and comprehension.

Six 3-year-old language-disordered children were taught the relationship between semantic role and word order through either production or comprehension training. All 6 subjects successfully learned the relationship through production training as indicated by their responses to a production probe and by their use of word order to express semantic role distinctions in their conversational speech. These subjects never used word order cues to decode semantically reversible sentences on comprehension tests even after they were using word order appropriately in their conversational speech. Also, none of the subjects were able to learn word order through comprehension training. The results were interpreted to mean the subjects could learn a word-order rule by teaching them to say sentences that contrast word order and meaning but that they could not learn by being taught to respond to sentences. The problem with this latter procedure may be that it requires a mental operation that is beyond the level of cognitive development of children under the age of 4.

Child, Preschool↗

PubMed1999

Speech and oral motor learning in individuals with cerebellar atrophy.

The purpose of this study was to determine whether cerebellar pathology interferes with motor learning for either speech or novel tasks. Practice effects were contrasted between persons with cerebellar cortical atrophy (CCA) and control participants on previously learned real speech, nonsense speech, and novel nonspeech oral-movement tasks. Studies of limb motor learning suggested that control participants would evidence reduced variability, increased speed of movement, and reduced movement amplitude with practice as compared with the CCA group. No significant differences were found between the real- and nonsense-speech tasks. For both speech tasks, although neither group reduced their movement variability with practice, both groups significantly reduced jaw closing displacement and velocity with practice. For the novel nonspeech oral-movement task, no change with practice was observed in either group in terms of variability, amplitude, or peak velocity. No effects of cerebellar pathology were seen in either the speech- or oral-movement tasks. These results demonstrated that with practice of speech tasks, a previously learned motor skill, movement speed and displacement decreased in both groups. Therefore, the effects of practice differed between previously learned speech tasks and the novel oral-movement task regardless of cerebellar pathology.

Adult↗

PubMedDate not supplied

The relation of affect to attention and learning in infancy.

The relation of positive affect to attention and learning was examined in 5-, 7-, and 9-month-olds (N = 84). Affect and attention were assessed while the infants inspected a photograph. Affect was rated globally, for overall mood, and specifically, for amount of time smiling. Attention was indexed by the duration of the infant's longest (or peak) look, a measure previously linked to differential cognitive performance. At all ages, positive affect (shown by approximately half the infants) was associated with long look durations and slower learning, as assessed on a task in which infants learned to distinguish a familiar face from a series of novel faces. By contrast, neutral affect was associated with short looks and faster learning. Affect and look duration had synergistic effects, in that learning was faster than expected for infants who displayed both short looks and neutral affect. These findings are compatible with adult research that links positive affect to less analytical processing, and provide the first evidence that affect may be associated with the speed of processing differences implicated in short and long looking.

Affect↗

PubMed1999

The social development of children with severe learning difficulties: a case study of an inclusive education initiative between two primary schools in Oxfordshire, UK.

This case study of primary age children in two linked Oxfordshire schools investigated the contribution of staff attitudes and practices to inequalities in education, and contrasted the socialisation of children with similar learning difficulties in different educational placements. Participant observation of a group of children and carers in a special school suggested areas of more rigorous inquiry. Structured observations compared this group with a matched sample of children with similar learning difficulties in a mainstream setting. Staff on both sites were invited to comment on findings arising from analysed data in order to identify attitudes and policies which might account for the observed differences in practice. The study was engendered by experience of differences arising from educational placement. The theoretical stance arose through reviewing previous work, predominantly the debate on inclusive education, and the wider issues of human rights and equal opportunities embedded in the social development of people with disabilities. The theoretical framework underpinning this study is established in some depth. The project was designed to investigate issues of the wider social perspective, by conducting a micro-study of one model of educational inclusion whose outcomes have direct relevance to those issues.

Child↗

PubMed2000

Impaired verbal category learning in amnesia.

Amnesic patients and controls listened to verbal descriptions of imaginary animals and then classified novel descriptions according to whether they belonged to the studied category. Controls performed well, but the amnesic patients did not acquire categorical knowledge. These findings contrast with previous demonstrations of intact category learning by amnesic patients for dot patterns, artificial grammars, and cartoon animals. It appears that category knowledge can be acquired implicitly when training exemplars are presented visually and when the similarities among items can be readily perceived. Verbal category learning requires the extraction and retention of meaning from training exemplars that are separated in time and may make demands on declarative memory that are beyond the capacity of amnesic patients.

Amnesia↗

PubMed2002

Human brain plasticity: evidence from sensory deprivation and altered language experience.

The results from the language studies taken as a whole point to different developmental time courses and developmental vulnerabilities of aspects of grammatical and semantic/lexical processing. They thus provide support for conceptions of language that distinguish these subprocesses within language. Similarly, following auditory deprivation, processes associated with the dorsal visual pathway were more altered than were functions associated with the ventral pathway, providing support for conceptions of visual system organization that distinguish functions along these lines. Could the effects observed in blind and deaf adults be accounted for, at least in part, by the redundant connectivity of the immature human brain? One way we tested this hypothesis was to study the differentiation of visual and auditory sensory responses in normal development (Neville, 1995). In normal adults, auditory stimuli elicit ERP responses that are large over temporal brain regions but small or absent over occipital regions. By contrast, in 6-month-old children we observed that auditory ERPs are equally large over temporal and visual brain regions, consistent with the idea that there is less specificity and more redundancy of connections between the auditory and visual cortex at this time. Between 6 and 36 months, however, we observed a gradual decrease in the amplitude of the auditory ERP over visual areas, while the amplitude over the temporal areas was unchanged. These results suggest that early in human development, there exists a redundancy of connections between auditory and visual areas and that this overlap gradually decreases after birth. This loss of redundancy may be a boundary condition that determines when sensory deprivation can result in alterations in the organization of remaining sensory systems. The considerable variability in timing of sensitive periods may also be in part due to temporal differences in the occurrence of redundancy within different systems. Ongoing studies of infants and children employing different types of stimuli will test for the specificity of these effects (Mitchell et al., 1999). Differences in the degree of plasticity may also be due to differences in the overall level of redundant connectivity within different systems. For example, it may be that aspects of sensory systems that are specialized for high spatial acuity (e.g., central vision and central audition) exhibit fewer developmental redundancies, decreased modifiability and more specificity than those displaying less acuity and precision (e.g., peripheral representations within vision and audition). There is some evidence for this hypothesis within the visual system (Chalupa and Dreher, 1991). In addition, there may be molecular differences between systems displaying different levels and patterns of experience-dependent plasticity. It is of interest that all levels of the dorsal pathway of the visual system, which in the studies reviewed here shows a high level of modifiability, displays strong immunoreactivity for the monoclonal antibody CAT 301 in macaque monkeys (DeYoe et al., 1990). By contrast there is very little labeling within the ventral visual pathway. Moreover, the expression of CAT 301 immunoreactivity shows marked experience-dependent plasticity, suggesting it may play a role in the guidance and/or stabilization of synaptic structure (Sur et al., 1988). Further research along these lines within the auditory system and in animal models of sensory deprivation and other developmental disorders may elucidate the role of specific molecular factors in the developmental plasticity of different neural systems. A related, more general hypothesis that may account for the different patterns of plasticity within both vision and language is that systems employing fundamentally different learning mechanisms (perhaps mediated by different anatomical and molecular substrates) display different patterns of developmental plasticity. It may be that systems that display experience-dependent change throughout life, including the topography of sensory maps (Merzenich et al., 1988; Gilbert, 1995; Kaas, 1995), lexical acquisition (i.e. object-word associations), and the establishment of form, face, and object representations (i.e., ventral pathway functions) rely upon very general, associative learning mechanisms that permit learning and adaptation throughout life. By contrast, systems that are important for computing dynamically shifting relations among locations, objects and events (including the dorsal visual pathway and the systems of the brain that mediate grammar) appear dependent on and modifiable by experience primarily during more limited periods in development. This could account for both the greater developmental deficits and enhancements of dorsal pathway function following various developmental anomalies and for the greater effects of altered language experience on grammatical functions. Further research is necessary to characterize systems that become constrained in this way and those that can be modified throughout life. This type of developmental evidence can contribute to fundamental descriptions of the architecture of different cognitive systems and can guide future studies of the cellular and molecular mechanisms important in neuroplasticity. Additionally, in the long run, they may contribute to the design of educational and habilitative programs for both normally and abnormally developing children.

Adaptation, Physiological↗

PubMed2001

Errors committed with high confidence are hypercorrected.

The relation between people's confidence in the accuracy of an erroneous response and their later performance was investigated. Most models of human memory suggest that the higher a person's confidence, the stronger the item (in the context of the eliciting cue) that is retrieved from memory. In recall, stronger associates to a cue interfere with competing associates more than do weaker associates. This state of affairs implies that errors endorsed with high, rather than low, confidence should be more difficult to correct by learning the correct response feedback. In contrast to the authors' expectations, highly confident errors were the most likely to be corrected in a subsequent retest. Participants nearly always endorsed the correct response in cases in which both the correct response and the original erroneous response were generated at retest, suggesting that people possess a refined metacognitive ability to know what is correct and incorrect.

Adult↗

PubMed2006

The role of perceptual learning on modality-specific visual attentional effects.

Morrone et al. [Morrone, M. C., Denti, V., & Spinelli, D. (2002). Color and luminance contrasts attract independent attention. Current Biology, 12, 1134-1137] reported that the detrimental effect on contrast discrimination thresholds of performing a concomitant task is modality specific: performing a secondary luminance task has no effect on colour contrast thresholds, and vice versa. Here we confirm this result with a novel task involving learning of spatial position, and go on to show that it is not specific to the cardinal colour axes: secondary tasks with red-green stimuli impede performance on a blue-yellow task and vice versa. We further show that the attentional effect can be abolished with continued training over 2-4 training days (2-20 training sessions), and that the effect of learning is transferable to new target positions. Given the finding of transference, we discuss the possibility that V4 is a site of plasticity for both stimulus types, and that the separation is due to a luminance-colour separation within this cortical area.

Attention↗

PubMed2006

Societal learning in epidemics: intervention effectiveness during the 2003 SARS outbreak in Singapore.

BACKGROUND: Rapid response to outbreaks of emerging infectious diseases is impeded by uncertain diagnoses and delayed communication. Understanding the effect of inefficient response is a potentially important contribution of epidemic theory. To develop this understanding we studied societal learning during emerging outbreaks wherein patient removal accelerates as information is gathered and disseminated. METHODS AND FINDINGS: We developed an extension of a standard outbreak model, the simple stochastic epidemic, which accounts for societal learning. We obtained expressions for the expected outbreak size and the distribution of epidemic duration. We found that rapid learning noticeably affects the final outbreak size even when learning exhibits diminishing returns (relaxation). As an example, we estimated the learning rate for the 2003 outbreak of severe acute respiratory syndrome (SARS) in Singapore. Evidence for relaxation during the first eight weeks of the outbreak was inconclusive. We estimated that if societal learning had occurred at half the actual rate, the expected final size of the outbreak would have reached nearly 800 cases, more than three times the observed number of infections. By contrast, the expected outbreak size for societal learning twice as effective was 116 cases. CONCLUSION: These results show that the rate of societal learning can greatly affect the final size of disease outbreaks, justifying investment in early warning systems and attentiveness to disease outbreak by both government authorities and the public. We submit that the burden of emerging infections, including the risk of a global pandemic, could be efficiently reduced by improving procedures for rapid detection of outbreaks, alerting public health officials, and aggressively educating the public at the start of an outbreak.

Communicable Diseases, Emerging↗

PubMed1999

Brain activity underlying stereotyped and non-stereotyped retrieval of learned stimulus-response associations.

When humans retrieve learned stimulus-response associations in a stereotyped manner the necessary brain structures may differ from those required when the same associations must be retrieved and adapted to new circumstances. We tested this hypothesis by means of tasks that resembled those employed in monkeys, using positron emission tomography (PET). Stimuli consisted of abstract two-dimensional shapes. Stereotyped retrieval of learned stimulus-response associations was studied by the use of a concurrent discrimination task with fixed pairing. This was contrasted with conditions requiring retrieval and adaptation of learned associations: forced-choice recognition, response reversal and concurrent discrimination with random pairing. Visuomotor control, passive viewing and fixation conditions were also included. During concurrent discrimination with fixed pairing, the left lower precentral gyrus and rostral anterior cingulate demonstrated higher blood flow levels in comparison with recognition, concurrent discrimination with random pairing, and to a lesser degree, response reversal. In the left lower precentral gyrus these blood flow levels were also higher in comparison with control conditions. Conversely, during recognition, concurrent discrimination with random pairing and reversal, a single region within the right inferior frontal gyrus demonstrated higher blood flow levels in comparison with concurrent discrimination with fixed pairing and control conditions. This right inferior frontal gyrus activation did not depend on the need for active familiarity judgements or response inhibition. To conclude, the left lower precentral gyrus is more active during stereotyped retrieval of learned stimulus-response associations and the right inferior prefrontal cortex is more active when a learned stimulus-response association must be retrieved and adapted to new circumstances.

Adult↗

PubMed1998

Differential involvement of the lateral and medial divisions of the septal area on spatial learning processes as revealed by intracranial self-administration of morphine in mice.

The present study was conducted to investigate the effects of morphine self-administration into either the medial or lateral divisions of the septal region on spatial discrimination abilities in mice. To this end, BALB/c mice received a dose of 5 ng/50 nl of morphine sulfate, via a stainless steel injection cannula, inserted into either the medial septal area (MS) or the lateral septal nucleus (LS), when they are close to the end of one of the two choice arms of a Y-maze (acquisition period). In these conditions a discrimination between the reinforced arm and the neutral arm is acquired in MS as well as in LS mice. However both acquisition and subsequent extinction (vehicle only available) was more rapid in the LS group than in the MS group. Moreover, during the extinction period, numerous escape attempts from the Y-maze were observed for MS mice. When the dose of morphine was raised to 50 ng the pattern of acquisition was unchanged in the LS group. In contrast animals of the MS group learned to avoid the arm where the higher dose of morphine was delivered thus allowing us to conclude that in MS animals the drug effect became aversive at this higher dose. This possibility was directly investigated in a second experiment by closing the access to the neutral arm. Thus, for a 5-ng dose the rewarding effect of morphine was demonstrated in both MS and LS groups by the decrease of self-administration latencies which, furthermore, were notably lower than in the discrimination situation. Moreover, with the dose of 50 ng of morphine the latencies were identical for the two groups and at their lowest value thus indicating that morphine had similar appetitive effects in MS as well as in LS mice in this situation. Thus, the previously observed deficit of MS subjects, including escape attempts, disappeared when the dose of morphine was raised and the experimental context simplified. These results which demonstrate differential functional properties of these two septal divisions are discussed in terms of conflict resulting from the strongly appetitive effects of the morphine which induces, in parallel, deleterious consequences on cognitive processing in MS self-injected mice.

Animals↗

PubMed1990

Children's use of information in word learning.

Whenever children hear a novel word, the context supplies information about its meaning. One way children may cope with so much information is to use whatever seems to make sense, given their prior knowledge and beliefs, while ignoring or quickly forgetting the rest. This work examined if and how children's beliefs about word meanings may affect their use of contrastive linguistic information in the input in word learning. In Study 1, some 3- and 4-year-olds were introduced to a novel material or shape name and heard it contrasted with familiar words. Others merely heard the novel word used for referring to an object. These children were then tested to determine what they had learned about their new word meaning. In Study 2, another group of 3- and 4-year-olds were asked to name the materials and shapes used for introducing these novel terms. Children made use of linguistic contrast only in some situations. They benefited more when the novel term did not overlap much in denotation with any terms commonly known by 3- and 4-year-olds. These results suggest that children can use information in the input very efficiently in learning a term for an as-yet-unnamed category, but not in learning a term similar in denotation to a word they already know. Thus, the results are consistent with the claim that children believe every word has a unique denotation.

Child Language↗

PubMed1987

Interhemispheric transfer of visual information in humans: spatial characteristics.

1. The problem of the interhemispheric transfer of visual information in humans has been approached psychophysically, making use of a visual discrimination task that shows a clear left field advantage and is subject to the phenomenon of perceptual learning. 2. For this task (discrimination of complex gratings differing only by the relative spatial phase of their harmonic components) there is a left field advantage and a lack of interhemispheric transfer of learning effects at all spatial frequencies tested for stimuli removed at least 5 deg from either side of the vertical meridian. 3. For stimuli close to the vertical meridian, the left field advantage disappears and there is a complete transfer of learning effects, provided the fundamental spatial frequency is 2 cycles/deg or lower. 4. At higher spatial frequencies the left field advantage is maintained and the learning effects do not transfer from one visual hemifield to the other, even at +/- 0.5 deg from the vertical meridian, unless the contrast is very high. 5. The transfer of learning effects obtained for spatial frequencies of 2 cycles/deg or lower is peculiar to regions placed close to the vertical meridian and symmetrically located on either side of it. No transfer is obtained between non-overlapping regions on the same side of the vertical meridian. 6. These findings are consistent with an interhemispheric transfer of visual information, preferential for low spatial frequencies and high contrasts, in agreement with that found for callosal transfer in the cat (Berardi, Bisti & Maffei, 1987).

Corpus Callosum↗

PubMed2002

Impaired spatial and sequential learning in rats treated neonatally with D-fenfluramine.

D-Fenfluramine, a serotonin releaser, was administered to neonatal rats on postnatal days 11-20 (a stage of hippocampal development analogous to third trimester human ontogeny). As adults, the D-fenfluramine-treated offspring exhibited dose-related impairments of sequential and spatial learning and reference memory in the absence of sensorimotor impairments. Procedures to minimize stress and to control for other performance effects prior to testing for spatial learning demonstrated that nonspecific factors did not account for the selective effects of D-fenfluramine on learning and memory. Developmental D-fenfluramine-induced spatial and sequential learning deficits are similar to previous findings with developmental MDMA treatment. By contrast, recent findings with developmental D-methamphetamine treatment showed spatial learning deficits while sparing sequential learning. The spatial learning effects common to all three drugs suggest that they may share a common mechanism of action, however, the effects are not related to long-lasting changes in hippocampal 5-HT levels as no differences were found in adulthood. Whether the cognitive deficits are related to the effects of substituted amphetamines on corticosteroids, other aspects of the 5-HT system, or some unidentified neuronal substrates is not known, but the data demonstrate that these drugs are all capable of inducing long-term adverse effects on learning.

Animals↗

PubMed2004

Reduction of single-neuron firing uncertainty by cortical ensembles during motor skill learning.

Motor skill learning is usually characterized by shortening of response time and performance of faster, more stereotypical movements. However, little is known about the changes in neural activity that underlie these behavioral changes. Here we used chronically implanted electrode arrays to record neuronal activity in the rat primary motor cortex (MI) as animals learned to execute movements in two directions. Strong modulation of MI single-neuron activity was observed while movement duration of the animal decreased. Despite many learning-induced changes, the precision with which single neurons fire did not improve with learning. Hence, prediction of movement direction from single neurons was bounded. In contrast, prediction of movement direction using neuronal ensembles improved significantly with learning, suggesting that, with practice, neuronal ensembles learn to overcome the uncertainty introduced by single-neuron stochastic activity.

Acoustic Stimulation↗

PubMed2004

Brain metabolites and cognitive function among older depressed and healthy individuals using 2D MR spectroscopy.

Brain metabolites of choline (Ch) and myo-Inisotol (mI) have been reported as elevated among geriatric depressed patients. Two-dimensional (2D) magnetic resonance spectroscopy (MRS) provides estimates of Ch, mI, and creatine (Cr) similar to one-dimensional MRS, and it also estimates the resonances of the Ch-containing compounds of phosphoethanolamine (Pe) and phosphocholine (PCh). In this cross-sectional geriatric study, 14 depressed patients and 14 healthy volunteers who were comparable in age, gender, education, comorbid medical burden, and Mini-Mental State Examination (MMSE) scores completed 2D MRS and a neurocognitive battery. A voxel in the left dorsolateral cortex, which was comprised of approximately 60% white matter, was used to estimate the CR ratios of Ch, PCh, Pe, and mI. Composite scores for cognitive function were developed for verbal learning, recall, recognition, executive function, hypothesis generation, and processing speed. Among nondepressed subjects, cognition was positively correlated with Ch/Cr and mI/Cr and negatively correlated with PCh/Cr in four domains of verbal learning, recognition, recall, and hypothesis generation. In contrast, depressed patients did not have consistent relationships between Ch/Cr, mI/Cr, and PCh/Cr and cognition. There was a significant difference in the overall pattern of associations between the four metabolites and verbal learning and processing speed in depressed patients compared to healthy controls. The attenuated relationship between metabolites and specific cognitive domains in patients with late-life MDD suggests that the level of cognitive performance observed during depressive episodes may be associated with changes in biochemistry within the frontostriatal neuronal circuitry.

Age Factors↗