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PubMed1996

The effect of first written language on the acquisition of English literacy.

The relationship between first and second language literacy was examined by identifying the skills and processes developed in the first language that were transferred to the second language. The performance of 40 university students from The People's Republic of China, Hong Kong, Vietnam and Australia were compared on a series of tasks that assessed phonological awareness and reading and spelling skills in English. The results indicated that the Hong Kong students (with non-alphabetic first language literacy) had limited phonological awareness compared to those students with alphabetic first language literacy. The reading and spelling tasks showed no differences between the groups on real word processing. However, the students from Hong Kong had difficulty processing nonwords because of their poor phonological awareness. The results supported the hypothesis that people learning English as a second language (ESL) transfer their literacy processing skills from their first language to English. When the phonological awareness required in English had not been developed in the first language, ESL students were limited to a whole-word, visual strategy. The findings indicate that students from non-alphabetic written language backgrounds might have difficulties with new, or unfamiliar words when attending universities where English is the medium of instruction.

Adult↗
PubMed1997

The transfer of avoidance evoking functions through stimulus equivalence classes.

Recent research in the area of stimulus equivalence suggests that transfer of function via members of stimulus equivalence classes may have relevance to human emotional responding and the development and generalization of certain psychological disorders. This study investigated the transfer of avoidance evoking functions through equivalence classes. Eight subjects were trained in the necessary relations for two-four member stimulus equivalence classes to emerge. Next, using an on-baseline classical conditioning procedure, one member of one class was paired with shock while one member of the other class was presented without shock. Then, while subjects engaged a key-press task, a differential, signalled avoidance task was introduced wherein shock was avoided if a response occurred to the stimulus previously associated with shock. The remaining stimuli from both classes were then presented. The behavior of all eight subjects showed the differential transfer of the avoidance evoking function. The clinical and theoretical implications of the results are discussed.

Avoidance Learning↗
PubMed1998

Increased transduction efficiency of primary hematopoietic cells by physical colocalization of retrovirus and target cells.

Efficient gene transfer into hematopoietic stem cells offers a number of potential therapeutic applications. However, the relatively low titer of retroviral supernatants and the requirement for cell division to ensure integration have meant that transduction efficiency has been low. We have modified a flowthrough approach to cell transduction and have been able consistently to increase gene transfer efficiency into human hematopoietic progenitor cells. We transduced CD34 cells with retroviral vectors encoding a truncated nerve growth factor receptor (NGFR) or neo. Retroviral supernatant was pulled through 0.2-micron polycarbonated membranes, followed by placement of cells on the filter. In the absence of cytokines, the transduction efficiency of CD34 cells with a NGFR vector was increased 3-11-fold over that obtained at an identical MOI in liquid culture to produce 11%-44% transduction. Furthermore, both Thy1+ and Thy1- subsets in a total CD34 population were transduced with similar efficiency, and transduction with a neo vector, as measured by G418 resistance in clonogenic assays, increased 1.5-5-fold. The mechanism by which gene transfer is improved may reflect colocalization of cells and retrovirus. Costaining of cells transduced on the filter with an NGFR retrovirus with both an NGFR antibody and a gp70 antibody that recognizes viral coat protein revealed high-level coexpression. The levels of in vitro gene transfer we obtain are equivalent to those observed when CD34 cells are cocultured in liquid culture with cytokines. However, culture with cytokines may commit CD34 cells to differentiation and has produced disappointingly low levels of subsequent in vivo gene transfer. Gene marking studies using distinguishable retroviral vectors will provide a means of learning whether the effects of flowthrough transduction genuinely enhance the efficiency of gene transfer to human marrow-repopulating cells.

Antigens, CD↗
PubMed2002

Single-use versus mixed-use learning of transformations: evidence for conceptual integration.

The principle of use-specificity proposes that "compiled" knowledge encapsulates the knowledge use in the acquisition context. The efficiency of knowledge use should be a monotone function of use-specific practice. Transfer between different uses of function concepts should decrease with increasing practice. In contrast, the hypothesis of conceptual integration proposes that conceptually integrated knowledge can be used flexibly. The efficiency of knowledge use should be a monotone function of concept-specific practice. The probability to integrate a feature is assumed to depend on its relevance within the acquisition context. Transfer between different uses of function concepts should increase with increasing practice. In Experiment 1, the effects of practicing a single versus two different uses of symbolic functions on learning and subsequent transfer were investigated at 1 day and 2 consecutive days of practice. In Experiment 2, these effects were investigated for 4 days of practice. The findings support the hypothesis of conceptual integration. Performance was mainly a function of concept-specific training. Limited usability of acquired knowledge was rare and disappeared completely at higher levels of practice.

Adult↗
PubMed2006

Heterarchical reinforcement-learning model for integration of multiple cortico-striatal loops: fMRI examination in stimulus-action-reward association learning.

The brain's most difficult computation in decision-making learning is searching for essential information related to rewards among vast multimodal inputs and then integrating it into beneficial behaviors. Contextual cues consisting of limbic, cognitive, visual, auditory, somatosensory, and motor signals need to be associated with both rewards and actions by utilizing an internal representation such as reward prediction and reward prediction error. Previous studies have suggested that a suitable brain structure for such integration is the neural circuitry associated with multiple cortico-striatal loops. However, computational exploration still remains into how the information in and around these multiple closed loops can be shared and transferred. Here, we propose a "heterarchical reinforcement learning" model, where reward prediction made by more limbic and cognitive loops is propagated to motor loops by spiral projections between the striatum and substantia nigra, assisted by cortical projections to the pedunculopontine tegmental nucleus, which sends excitatory input to the substantia nigra. The model makes several fMRI-testable predictions of brain activity during stimulus-action-reward association learning. The caudate nucleus and the cognitive cortical areas are correlated with reward prediction error, while the putamen and motor-related areas are correlated with stimulus-action-dependent reward prediction. Furthermore, a heterogeneous activity pattern within the striatum is predicted depending on learning difficulty, i.e., the anterior medial caudate nucleus will be correlated more with reward prediction error when learning becomes difficult, while the posterior putamen will be correlated more with stimulus-action-dependent reward prediction in easy learning. Our fMRI results revealed that different cortico-striatal loops are operating, as suggested by the proposed model.

Association Learning↗
PubMed1994

Effects of (R)-alpha-methylhistamine and scopolamine on spatial learning in the rat assessed using a water maze.

The effects of (R)-alpha-methylhistamine ((R)-alpha-MeHA, a selective H3-receptor agonist) and scopolamine (SCOP, a muscarinic antagonist) were investigated on spatial learning and memory in the rat (Hooded Lister) using a water maze (WM). (R)-alpha-MeHA treatment (6.3 and 10 mg/kg IP) had no apparent effect on spatial learning but did result in enhanced spatial recall at the higher dose, assessed by a transfer (probe) test after training. In contrast, SCOP (0.5 mg/kg IP) induced a learning and memory deficit measured both during and after training. In animals treated with (R)-alpha-MeHA and SCOP, (R)-alpha-MeHA partially (6.3 mg/kg) and completely (10 mg/kg) reversed the SCOP-induced deficit during the training phase, while in the post-training transfer test, (R)-alpha-MeHA (10 mg/kg) significantly reduced the SCOP-induced memory deficit. None of the treatments described resulted in impaired visual acuity as demonstrated by a raised platform test. These results are consistent with a role for histamine in cognitive processes and suggest a possible interaction between central histamine and cholinergic mechanisms associated with rodent spatial learning and memory.

Animals↗
PubMed1994

Value-dependent selection in the brain: simulation in a synthetic neural model.

Many forms of learning depend on the ability of an organism to sense and react to the adaptive value of its behavior. Such value, if reflected in the activity of specific neural structures (neural value systems), can selectively increase the probability of adaptive behaviors by modulating synaptic changes in the circuits relevant to those behaviors. Neuromodulatory systems in the brain are well suited to carry out this process since they respond to evolutionarily important cues (innate value), broadcast their responses to widely distributed areas of the brain through diffuse projections, and release substances that can modulate changes in synaptic strength. The main aim of this paper is to show that, if value-dependent modulation is extended to the inputs of neural value systems themselves, initially neutral cues can acquire value. This process has important implications for the acquisition of behavioral sequences. We have used a synthetic neural model to illustrate value-dependent acquisition of a simple foveation response to a visual stimulus. We then examine the improvement that ensues when the connections to the value system are themselves plastic and thus become able to mediate acquired value. Using a second-order conditioning paradigm, we demonstrate that auditory discrimination can occur in the model in the absence of direct positive reinforcement and even in the presence of slight negative reinforcement. The discriminative responses are accompanied by value-dependent plasticity of receptive fields, as reflected in the selective augmentation of unit responses to valuable sensory cues. We then consider the time-course during learning of the responses of the value system and the transfer of these responses from one sensory modality to another. Finally, we discuss the relation of value-dependent learning to models of reinforcement learning. The results obtained from these simulations can be directly related to various reported experimental findings and provide additional support for the application of selectional principles to the analysis of brain and behavior.

Animals↗
PubMed1991

Methodology for motor learning: a paradigm for kinematic feedback.

Knowledge of results (KR)--information feedback about goal achievement--has been one of the most extensively examined variables in motor learning. In most natural movement learning situations, however, instructors more common]y provide augmented information regarding various kinematic or kinetic aspects of the movement pattern itself (sometimes termed knowledge of performance, KP). But despite the inherent interest in kinematic feedback, several factors reviewed here have operated to inhibit its study, the most important of which has been the lack of a suitable laboratory task and paradigm. The limitations of earlier paradigms have concerned (a) the use of overly simple motor behaviors, probably to minimize the problems in kinematic measurement, (b) the tendency for the environmental goal or the task to be isomorphic with the kinematic pattern, and (c) thc failure to use transfer or retention tests as measures of learning effects of the feedback manipulations. In this article, we describe our efforts to create a new paradigm for kinematic feedback, the rationale for its development, and the details of its operation. Finally, we provide evidence that the task and paradigm are sensitive to manipulations of kinematic feedback, providing some assurance that the paradigm can potentially answer future research questions about the role of kinematic feedback for learning.

Journal Article↗
PubMed2003

Social learning by orangutans (Pongo abelii and Pongo pygmaeus) in a simulated food-processing task.

Increasing evidence for behavioral differences between populations of primates has created a resurgence of interest in examining mechanisms of information transfer between individuals. The authors examined the social transmission of information in 15 captive orangutans (Pongo abelii and Pongo pygmaeus) using a simulated food-processing task. Experimental subjects were shown 1 of 2 methods for removing a suite of defenses on an "artificial fruit." Control subjects were given no prior exposure before interacting with the fruit. Observing a model provided a functional advantage in the task, as significantly more experimental than control subjects opened the fruit. Within the experimental groups, the authors found a trend toward differences in the actual behaviors used to remove 1 of the defenses. Results support observations from the wild implying horizontal transfer of information in orangutans and show that a number of social learning processes are likely to be involved in the transfer of knowledge in this species.

Animal Communication↗
PubMed2002

10 steps to a successful governance transfer.

The governance of several provincial psychiatric hospitals was transferred to the public hospitals across Ontario, with London and St. Thomas being two of them There were many learnings gained from the London/St. Thomas experience that can be taken forward to other transfers such as this. The keys to success included having a central negotiating table across all receiving hospitals, developing principles or values for a common vision across all parties, effective communication and commitment to the process. These learnings will be brought forward into Tier 2 and 3 of the transfers, when beds and programs will decentralize across Southwestern Ontario, and a reinvestment in community mental health will support the de-institutionalization of mental healthcare.

Canada↗
PubMed1991

Stimulus complexity effects in visual comparisons: the effects of practice and learning context.

This study examined visual comparison performance for 6-24-point random polygon stimuli (Cooper & Podgorny, 1976). Stimulus complexity effects decreased with practice, consistent with Bethell-Fox and Shepard (1988). A difficult discrimination context produced greater complexity effects than an easy discrimination context, consistent with Folk and Luce (1987). The difficult discrimination context also led to more stimulus-specific learning and diminished stimulus complexity effects. Increased stimulus learning resulted in continued skill acquisition, better transfer, and less performance disruption when the task context was equated for all Ss. It is argued that improvements in performance in a perceptual comparison task are not solely a function of the amount of practice provided in responding to particular stimuli. The context in which responses are elicited is equally important and must be accommodated in theories of skill acquisition.

Adolescent↗
PubMed2005

Coordinate processing during the left-to-right hand transfer investigated by EEG.

Information about visuomotor tasks is coded in extrinsic, object-centered and intrinsic, body-related coordinates. For the reproduction of a trained task in mirror orientation with the opposite untrained hand, acquired extrinsic coordinates must be transformed. In contrast, intrinsic coordinates have to be modified during the execution of the originally oriented task. As shown recently, processes of coordinate transformations during the right-to-left hand transfer are associated with movement preparation and occur preferentially in the left hemisphere. Here, movement-related potentials, EEG power, and EEG coherence were recorded during the repetition of a drawing task previously trained by the nondominant left hand (Learned-task) and its execution in original and mirror orientation by the right hand (Normal- and Mirror-task). To identify EEG correlates of coordinate processing during intermanual transfer rather than effects due to the use of the right versus left hand, only those EEG data were analyzed which differed between the Normal- and Mirror-tasks. Whereas the Normal-task did not differ from the Learned-task in any of these predefined EEG parameters, beta coherence increased in the Mirror-task in the period ranging from 1 to 2 s after movement onset. These increases were especially prominent between hemispheres but were also observed symmetrically in the parieto-frontal electrode pairs of both hemispheres. Behavioral data revealed that the performance in the Learned- and both transfer tasks improved after left-hand training. Results of the present study indicate that coordinate transformation during the left-to-right hand transfer occurs in the phase of movement execution and affects predominantly extrinsic coordinates. Intrinsic coordinates are presumably mainly used in their original form. The modification of extrinsic coordinates is accompanied by increased information flow between both hemispheres; thereby inter-hemispheric connections--as mediated via the corpus callosum--seem to play a central role.

Adult↗
PubMed1995

Effects of galanin on passive avoidance response, elevated plus-maze learning, and spontaneous alternation performance in mice.

The present study was done to characterize the effects of intracerebroventricular injection of galanin (GAL) on memory processes by observing passive avoidance response, elevated plus-maze learning, and spontaneous alternation performance in mice. An intermediate dose (3 micrograms) of GAL (3 micrograms) significantly decreased step-down latency of passive avoidance response when given 15 min before training, whereas in particular the middle doses (0.3 and 1 microgram) of GAL significantly decreased it when given 15 min before retention tests. However, GAL (0.3-10 micrograms) was ineffective when given immediately after training. Physostigmine (0.2 mg/kg), a cholinesterase inhibitor, and oxotremorine (0.01 and 0.03 mg/kg), a cholinergic agonist, significantly inhibited the shortening of step-down latency induced by GAL (0.3 microgram) administered 15 min before retention tests, indicating the involvement of cholinergic dysfunction in the GAL (0.3 microgram)-induced shortening of step-down latency. In contrast, GAL (0.3-3 micrograms) failed to influence transfer latency in elevated plus-maze learning or percent alternation in spontaneous alternation performance. These results suggest that the activation of cholinergic neurons improves memory dysfunctions induced by GAL, which primarily impairs retrieval processes of memory. The lack of effects of GAL on the elevated plus-maze learning and spontaneous alternation performance may result from the selective effects of GAL in different learning paradigms.

Amino Acid Sequence↗
PubMed1979

Learning when reward is delayed: a marking hypothesis.

Rats were trained on spatial discriminations in which reward was delayed for 1 min. Experiment 1 tested Lett's hypothesis that responses made in the home cage during the delay interval are less likely to interfere with learning than responses made in the maze. Experimental subjects were transferred to their home cages during the delay interval, and control subjects were picked up but then immediately replaced in the maze. Contrary to Lett's hypothesis, both groups learned. Further experiments suggested that handling following a choice response was the crucial variable in producing learning: No learning occurred when handling was delayed (Experiment 2) or omitted (Experiment 3). One possible explanation for the fact that handling facilitated learning is that it served to mark the preceding choice response in memory so that subjects were then more likely to recall it when subsequently reinforced. In accordance with this interpretation, learning was found to be just as strong when the choice response was followed by an intense light or noise as by handling (Experiment 4). The implication of marking for other phenomena such as avoidance, quasi-reinforcement, and the paradoxical effects of punishment is also discussed.

Animals↗