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At least 865 records · Page 48Linked to original sources
PubMed2005

Imitation: is cognitive neuroscience solving the correspondence problem?

Imitation poses a unique problem: how does the imitator know what pattern of motor activation will make their action look like that of the model? Specialist theories suggest that this correspondence problem has a unique solution; there are functional and neurological mechanisms dedicated to controlling imitation. Generalist theories propose that the problem is solved by general mechanisms of associative learning and action control. Recent research in cognitive neuroscience, stimulated by the discovery of mirror neurons, supports generalist solutions. Imitation is based on the automatic activation of motor representations by movement observation. These externally triggered motor representations are then used to reproduce the observed behaviour. This imitative capacity depends on learned perceptual-motor links. Finally, mechanisms distinguishing self from other are implicated in the inhibition of imitative behaviour.

Animals↗
PubMed2003

Suppression of cortical representation through backward conditioning.

Temporal stimulus reinforcement sequences have been shown to determine the directions of synaptic plasticity and behavioral learning. Here, we examined whether they also control the direction of cortical reorganization. Pairing ventral tegmental area stimulation with a sound in a backward conditioning paradigm specifically reduced representations of the paired sound in the primary auditory cortex (AI). This temporal sequence-dependent bidirectional cortical plasticity modulated by dopamine release hypothetically serves to prevent the over-representation of frequently occurring stimuli resulting from their random pairing with unrelated rewards.

Adaptation, Physiological↗
PubMed2006

Cross-modal plasticity of the motor cortex while listening to a rehearsed musical piece.

Learning a musical piece requires the development of a strong linkage between sensory and motor representations. Audition plays a central role and a tight cortical auditory-motor corepresentation is a characteristic feature of music processing. Recent works have indicated the establishment of a functional connection between auditory and motor cortices during the learning of a novel piece, although no causal relation has yet been demonstrated. Here transcranial magnetic stimulation of the cortical motor representation involved in musical performance was used to test excitability changes in piano players during auditory presentation of a rehearsed and a non-rehearsed piece. Results showed an increased motor excitability for the rehearsed but not for the non-rehearsed piece. Moreover, we observed an increase of excitability over time as intracortical facilitation was already present after 30 min of training whereas cortico-spinal facilitation increased after a longer training period (5 days).

Acoustic Stimulation↗
PubMed2006

Spatial vs temporal continuity in view invariant visual object recognition learning.

We show in a 4-layer competitive neuronal network that continuous transformation learning, which uses spatial correlations and a purely associative (Hebbian) synaptic modification rule, can build view invariant representations of complex 3D objects. This occurs even when views of the different objects are interleaved, a condition where temporal trace learning fails. Human psychophysical experiments showed that view invariant object learning can occur when spatial but not temporal continuity applies because of interleaving of stimuli, although sequential presentation, which produces temporal continuity, can facilitate learning. Thus continuous transformation learning is an important principle that may contribute to view invariant object recognition.

Computer Simulation↗
PubMed2005

Differential regulation of cortical NMDA receptor subunits by sensory learning.

NMDA receptor is an important player in neuronal plasticity, including cortical reorganization. In the adult cerebral cortex, the receptor properties are regulated by relative expression of NR2A and NR2B subunits. We have previously found that 3 days of sensory conditioning, in which stimulation of whiskers was paired with a tail shock, induce NMDA-receptor-dependent expansion of metabolically labeled cortical representations of the stimulated vibrissae. Here, we examined the effect of learning-induced cortical reorganization upon expression of NR2A and NR2B NMDA receptor subunits. An increase in NR2A mRNA expression in the barrel of the "trained" row of vibrissae was observed with in situ hybridization 24 h after sensory conditioning. NR2B mRNA expression level did not change. Protein level of both regulatory subunits and obligatory NR1 subunit were examined in P2 fraction. NR2A protein level was found elevated 1 h and 24 h after the sensory conditioning, but not in controls which received only whisker stimulation, signifying that the change was associated with cortical map reorganization. NR2B protein level was transiently elevated in both trained and stimulated control groups. NR1 protein level did not change. The results show that simple sensory learning induces a change in expression of regulatory NMDA receptor subunits, indicating a potential for receptor channel properties modification.

Animals↗
PubMed1991

Aphasia in polyglots: report of two cases and analysis of the literature.

Two cases of aphasia in polyglot patients who experienced different symptoms in each of the languages they knew are reported. The authors discuss the problem and analyze the available literature in an attempt to formulate a pathogenetic hypothesis of the different involvement of the known idioms sometimes observed in aphasic polyglots. In particular, when time has elapsed between the learning of the mother tongue and other languages, and all the known languages are, consequently, functionally independent, it is possible that the two or more known idioms have distinct anatomical representations, probably localized separately in the two hemispheres. This could explain why, in some polyglots, aphasia affects one of the known languages preferentially. In subjects in whom the different known idioms were learned during early childhood, the anatomical representation of the languages is similar, which explains why, in this kind of polyglot, all the known languages can be equally affected by cerebral damage that causes aphasia.

Adult↗
PubMed2006

Spatial relational memory in 9-month-old macaque monkeys.

This experiment assesses spatial and nonspatial relational memory in freely moving 9-mo-old and adult (11-13-yr-old) macaque monkeys (Macaca mulatta). We tested the use of proximal landmarks, two different objects placed at the center of an open-field arena, as conditional cues allowing monkeys to predict the location of food rewards hidden in one of two sets of three distinct locations. Monkeys were tested in two different conditions: (1) when local visual cues marked the two sets of potentially baited locations, so that monkeys could use both local and spatial information to discriminate these locations from never-baited locations; and (2) when no local visual cues marked the two sets of potentially baited locations, so that monkeys had to rely on a spatial relational representation of the environment to discriminate these locations. No 9-mo-old or adult monkey associated the presence of the proximal landmarks, at the center of the arena, with the presence of food in one set of three distinct locations. All monkeys, however, discriminated the potentially baited locations in the presence of local visual cues, thus providing evidence of visual discrimination learning. More importantly, all 9-mo-old monkeys tested discriminated the potentially baited locations in absence of the local visual cues, thus exhibiting evidence of spatial relational learning. These findings indicate that spatial memory processes characterized by a relational representation of the environment are present as early as 9 mo of age in macaque monkeys.

Age Factors↗
PubMed1995

A clinical concept of the self: the experiential being.

This paper proposes a clinical concept of the self as experiential being. Such a concept offers the triple advantage of being non-reductive, introducing experience as a clinical unit of analysis and intervention, and viewing a representational capacity to experience as a crucial element towards the construction of 'T'. The central importance of 'experience' in health and disorder is addressed, followed by a characterization of the processes of 'going through', the integration of 'experience' into 'I' and the processes of defence, which are viewed from the perspective of the experiential being. Experience, or 'going through', has five defining characteristics: awareness, motivation, linking, learning and evolution. The processing of 'experience' on two levels, the representational level and the level of the experimental being, leads to the integration of experience into "I'. The owning of experience, and not defence, is seen as the key factor in health and disorder. As the capacity to own experience, which includes the owning of defence, is the key to the road to health, it is argued that clinical intervention must focus on the person's capacity to own all his or her experiences.

Awareness↗
PubMed2004

Hippocampal plasticity across multiple days of exposure to novel environments.

The hippocampus is essential for learning complex spatial relationships, but little is known about how hippocampal neural activity changes as animals learn about a novel environment. We studied the formation of new place representations in rats by examining the changes in place-specific firing of neurons in the CA1 region of the hippocampus and the relationship between these changes and behavioral change across multiple days of exposure to novel places. We found that many neurons showed very rapid changes on the first day of exposure to the novel place, including many cases in which a previously silent neuron developed a place field over the course of a single pass through the environment. Across the population, the largest changes in neural activity occurred on day 2 of exposure to a novel place, but only if the animal had little experience (<4 min) in that location on day 1. Longer exposures on day 1 were associated with smaller changes on day 2, suggesting that hippocampal neurons required 5-6 min of experience to form a stable spatial representation. Even after the representation stabilized, the animals' behavior remained different in the novel places, suggesting that other brain regions continued to distinguish novel from familiar locations. These results show that the hippocampus can form new spatial representations quickly but that stable hippocampal representations are not sufficient for a place to be treated as familiar.

Animals↗
PubMed1984

Classical conditioning enhances auditory 2-deoxyglucose patterns in the inferior colliculus.

The [14C]2-deoxyglucose (2-DG) method in conjunction with a heart rate conditioning paradigm was used to investigate whether associative pavlovian conditioning of an acoustic stimulus (CS) with an aversive reticular stimulus (US) would result in a learning-induced metabolic response within the rat inferior colliculus (IC). The data show that: (1) the arousal level of the animal can result in a sensitization of the IC to subsequent auditory stimuli, and (2) the overlapping area of spatial representation of US and CS within the IC selectively develops an enhanced metabolic response during training and as a result of learning. Our results support the conclusion that within the same neuronal space of the IC there is representation not only of the physical parameters of a stimulus but also of its learned behavioral significance.

Acoustic Stimulation↗
PubMed1998

A neuropsychological theory of motor skill learning.

This article describes a neuropsychological theory of motor skill learning that is based on the idea that learning grows directly out of motor control processes. Three motor control processes may be tuned to specific tasks, thereby improving performance: selecting spatial targets for movement, sequencing these targets, and transforming them into muscle commands. These processes operate outside of awareness. A 4th, conscious process can improve performance in either of 2 ways: by selecting more effective goals of what should be changed in the environment or by selecting and sequencing spatial targets. The theory accounts for patterns of impairment of motor skill learning in patient populations and for learning-related changes in activity in functional imaging studies. It also makes a number of predictions about the purely cognitive, including accounts of mental practice, the representation of motor skill, and the interaction of conscious and unconscious processes in motor skill learning.

Amnesia↗
PubMed2002

[From informed to shared: the developing process of consent].

Based on the respect of the four well known ethical principles "autonomy, non-maleficence, beneficence and justice", of clinical cognitive psychology, social psychology and bioethics, and in the light of moral values, we wish to comment the clinical problems involving informed consent for diagnostic procedures, treatment and research in pediatrics. Studies of the issues in attitudes and shared consent in the clinical management involving children, their parents and the therapeutic team are still limited. Our suggestion is to manage the process of informed consent as a negotiated "shared consent" originated from the cognitive social representation theory, and taking into consideration the evolutive characteristics of the cognitive processes in children and adolescents, the ego defence mechanisms, the coping behaviour activated in the relationship among the pediatric patient, his/her family and the physicians. Many parents told us that the informed consent process is helpful though often confusing. Satisfaction was not related to ethnicity or education level. They found discussions more helpful than the consent documents. The more difficult process concerned their understanding of the concept of randomisation and the request of their consent to this procedure. The model we suggest has also the aim to give adequate and honest informations to children and adolescents through a continuous dialogue with the physician, until this become a routine part of their life in hospital care, to avoid confusion, to satisfy any request and curiosity, to be honest and helpful with any answer. We strongly believe that medical students, and in particular pediatricians, must be trained on "communication" and that they need to acquire, in addition to their medical capability, a good knowledge on this topic, including ethics and relational aspects. In our opinion, pediatricians must become expert also in the following topics: "Problem-related Learning", "The Family System Health Model", "The Theory of Social Representations", "Gadamerian Hermeneutics", and "The Communicative Skills".

Child↗
PubMed1993

Long-term potentiation of hippocampal afferents and efferents to prefrontal cortex: implications for associative learning.

It has been proposed that the physical substrate of memory resides in alterations of the strengths or weights of modifiable synaptic connections. In recent years, the hypothesis that the mechanisms underlying a particular form of synaptic plasticity, known as long-term potentiation, or LTP, are activated during learning and may actually subserve the formation of associative memories, has gained much empirical support. This paper reviews experimental studies suggesting that changes in synapse physiology and chemistry are involved in the formation of neural associative representation in hippocampal networks during classical conditioning. Recent experiments investigating LTP and learning-induced synaptic changes at hippocampal outputs to the prefrontal cortex are reported. The results provide a working framework within which the dynamics of information storage in hippocampal and prefrontal cortical networks is profiled.

Animals↗
PubMed2004

How laminar frontal cortex and basal ganglia circuits interact to control planned and reactive saccades.

How does the brain learn to balance between reactive and planned behaviors? The basal ganglia (BG) and frontal cortex together allow animals to learn planned behaviors that acquire rewards when prepotent reactive behaviors are insufficient. This paper proposes a new model, called TELOS, to explain how laminar circuitry of the frontal cortex, exemplified by the frontal eye fields, interacts with the BG, thalamus, superior colliculus, and inferotemporal and parietal cortices to learn and perform reactive and planned eye movements. The model is formulated as fourteen computational hypotheses. These specify how strategy priming and action planning (in cortical layers III, Va and VI) are dissociated from movement execution (in layer Vb), how the BG help to choose among and gate competing plans, and how a visual stimulus may serve either as a movement target or as a discriminative cue to move elsewhere. The direct, indirect and hyperdirect pathways through the BG are shown to enable complex gating functions, including deferred execution of selected plans, and switching among alternative sensory-motor mappings. Notably, the model can learn and gate the use of a What-to-Where transformation that enables spatially invariant object representations to selectively excite spatially coded movement plans. Model simulations show how dopaminergic reward and non-reward signals guide monkeys to learn and perform saccadic eye movements in the fixation, single saccade, overlap, gap, and delay (memory-guided) saccade tasks. Model cell activation dynamics quantitatively simulate seventeen established types of dynamics exhibited by corresponding real cells during performance of these tasks.

Animals↗
PubMed2006

Neural systems implicated in delayed and probabilistic reinforcement.

This review considers the theoretical problems facing agents that must learn and choose on the basis of reward or reinforcement that is uncertain or delayed, in implicit or procedural (stimulus-response) representational systems and in explicit or declarative (action-outcome-value) representational systems. Individual differences in sensitivity to delays and uncertainty may contribute to impulsivity and risk taking. Learning and choice with delayed and uncertain reinforcement are related but in some cases dissociable processes. The contributions to delay and uncertainty discounting of neuromodulators including serotonin, dopamine, and noradrenaline, and of specific neural structures including the nucleus accumbens core, nucleus accumbens shell, orbitofrontal cortex, basolateral amygdala, anterior cingulate cortex, medial prefrontal (prelimbic/infralimbic) cortex, insula, subthalamic nucleus, and hippocampus are examined.

Animals↗
PubMed2005

Effects of long-term practice and task complexity in musicians and nonmusicians performing simple and complex motor tasks: implications for cortical motor organization.

Motor practice induces plastic changes within the cortical motor system. Whereas rapidly evolving changes of cortical motor representations were the subject of a number of recent studies, effects of long-term practice on the motor system are so far poorly understood. In the present study pianists and nonmusicians were investigated using functional magnetic resonance imaging. Both groups performed simple and complex movement sequences on a keyboard with the right hand, the tasks requiring different levels of ordinal complexity. The aim of this study was to characterize motor representations related to sequence complexity and to long-term motor practice. In nonmusicians, complex motor sequences showed higher fMRI activations of the presupplementary motor area (pre-SMA) and the rostral part of the dorsal premotor cortex (PMd) compared to simple motor sequences, whereas musicians showed no differential activations. These results may reflect the higher level of visuomotor integration required in the complex task in nonmusicians, whereas in musicians this rostral premotor network was employed during both tasks. Comparison of subject groups revealed increased activation of a more caudal premotor network in nonmusicians comprising the caudal part of the PMd and the supplementary motor area. This supports recent results suggesting a specialization within PMd. Furthermore, we conclude that plasticity due to long-term practice mainly occurs in caudal motor areas directly related to motor execution. The slowly evolving changes in M1 during motor skill learning may extend to adjacent areas, leading to more effective motor representations in pianists.

Adult↗
PubMed2004

Memory enhancement of classical fear conditioning by post-training injections of corticosterone in rats.

There is extensive evidence that post-training administration of the adrenocortical hormone corticosterone facilitates memory consolidation processes in a variety of contextual and spatial-dependent learning situations. The present experiments examine whether corticosterone can modulate memory of auditory-cue classical fear conditioning, a learning task that is not contingent on contextual or spatial representations. Male Sprague-Dawley rats received three pairings of a single-frequency auditory stimulus and footshock, followed immediately by a post-training subcutaneous injection of either corticosterone (1.0 or 3.0mg/kg) or vehicle. Retention was tested 24h later in a novel test chamber and suppression of ongoing motor behavior served as the measure of conditioned fear. Corticosterone dose-dependently facilitated suppression of motor activity during the 10-s presentation of the auditory cue. As corticosterone administration did not alter responding after unpaired presentations of tone and shock, tone alone, shock alone or absence of tone/shock, the findings indicated that corticosterone selectively facilitated memory of the tone-shock association. Furthermore, injections of corticosterone given 3h after training did not alter motor activity during retention testing, demonstrating that corticosterone enhanced time-dependent memory consolidation processes. These findings provide evidence that corticosterone modulates the consolidation of memory for auditory-cue classical fear conditioning and are consistent with a wealth of data indicating that glucocorticoids can modulate a wide variety of emotionally influenced memories.

Animals↗