Innate and learned components of human visual preference.
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BACKGROUND: Recent claims in neuroscience and evolutionary biology suggest that the aesthetic sense reflects preferences for image signals whose characteristics best fit innate brain mechanisms of visual recognition. RESULTS: This hypothesis was tested by behaviourally measuring, for a set of initially unfamiliar images, the effects of category learning on preference judgements by humans, and by relating the observed data to computationally reconstructed internal representations of categorical concepts. Category learning induced complex shifts in preference behaviour. Two distinct factors - complexity and bilateral symmetry - could be identified from the data as determinants of preference judgements. The effect of the complexity factor varied with object knowledge acquired through category learning. In contrast, the impact of the symmetry factor proved to be unaffected by learning experience. Computer simulations suggested that the preference for pattern complexity relies on active (top-down) mechanisms of visual recognition, whereas the preference for pattern symmetry depends on automatic (bottom-up) mechanisms. CONCLUSIONS: Human visual preferences are not fully determined by (objective) structural regularities of image stimuli but also depend on their learned (subjective) interpretation. These two aspects are reflected in distinct complementary factors underlying preference judgements, and may be related to complementary modes of visual processing in the brain. (+info)
Odors: implicit memory and performance effects.
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In order to assess the influence of odors on human performance and implicit memory for odors, 108 subjects completed a variety of tests in weakly scented (jasmine, lavender or odorless) rooms without having been made aware of the odor. After a 30 min interval the subjects were shown slides of different surroundings, including the room they had been in, and were requested to rate how well a set of 12 odors, including a blank, would fit to these surroundings. Half of these contexts contained visual cues related to two of the presented odors (leather and coffee). After the rating of fit the subjects had to rate the odors for pleasantness, were asked to identify the odors with their correct names and to tell where and when they had last smelled these odors. One subject remembered smelling the odor (jasmine) in the room and was discarded from the analysis of the results for the rating of fit. None of the others reported recollection of the experimental odors. The results showed that in general jasmine had a negative and lavender a positive effect on test performance. If an odor-related visual cue was present in the context, the related odor was always rated highest in fit to that context. Furthermore, the subjects working in rooms with an odor subsequently assigned this odor to the visual context of that room to a significantly higher degree than subjects working in rooms with different odors. Since none of the subjects reported that they had smelled the odor in the rooms where performance testing took place, it was concluded that the memory for these odors was implicit. Further analysis showed that such memory was only found in subjects who were unable to supply the right name for the odor. The possible consequences of this latter finding for understanding the relationship between sensory (episodic) and semantic odor memory are discussed. (+info)
An unlearned principle for controlling natural movements.
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Recently, Gottlieb and colleagues discovered a linear relation between elbow and shoulder dynamic torque in natural pointing movements in the sagittal plane. The present study investigates if the process of learning to reach involves discovering this linearity principle. We inspected torque data from four infants who were learning to reach and grab a toy in front of them. In a longitudinal study, we collected data both in the period before and after they performed their first successful reaches. Torque profiles at the shoulder and elbow were typically multipeaked and became more and more biphasic toward the end of the first year of life. Torques at the shoulder and elbow were correlated tightly for movements in the prereaching period as well as for reaches later in the year. Furthermore, slopes of a regression of shoulder dynamic torque on elbow dynamic torque were remarkably constant at a value approximately 2.5-3.0. If linear synergy is used by the nervous system to reduce the controlled degrees of freedom, it will act as a strong constraint on the complex of possible coordination patterns for arm movement early in life. Natural reaching movements can capitalize on this constraint because it simplifies the process of learning to reach. (+info)
Nociceptin/orphanin FQ and nocistatin on learning and memory impairment induced by scopolamine in mice.
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1. Nociceptin, also known as orphanin FQ, is an endogenous ligand for the orphan opioid receptor-like receptor 1 (ORL1) and involves in various functions in the central nervous system (CNS). On the other hand, nocistatin is recently isolated from the same precursor as nociceptin and blocks nociceptin-induced allodynia and hyperalgesia. 2. Although ORL1 receptors which display a high degree of sequence homology with classical opioid receptors are abundant in the hippocampus, little is known regarding their role in learning and memory. 3. The present study was designed to investigate whether nociceptin/orphanin FQ and nocistatin could modulate impairment of learning and memory induced by scopolamine, a muscarinic cholinergic receptor antagonist, using spontaneous alternation of Y-maze and step-down type passive avoidance tasks in mice. 4. While nocistatin (0.5-5.0 nmol mouse-1, i.c.v.) administered 30 min before spontaneous alternation performance or the training session of the passive avoidance task, had no effect on spontaneous alternation or passive avoidance behaviours, a lower per cent alternation and shorter median step-down latency in the retention test were obtained in nociceptin (1.5 and/or 5.0 nmol mouse-1, i.c.v.)-treated normal mice. 5. Administration of nocistatin (1.5 and/or 5.0 nmol mouse-1, i.c.v.) 30 min before spontaneous alternation performance or the training session of the passive avoidance task, attenuated the scopolamine-induced impairment of spontaneous alternation and passive avoidance behaviours. 6. These results indicated that nocistatin, a new biologically active peptide, ameliorates impairments of spontaneous alternation and passive avoidance induced by scopolamine, and suggested that these peptides play opposite roles in learning and memory. (+info)
latheo, a Drosophila gene involved in learning, regulates functional synaptic plasticity.
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Mutations in the latheo (lat) gene disrupt associative learning in Drosophila , but a role for LAT in regulating neuronal function has not been demonstrated. Here, we report that LAT plays a central role in regulating Ca2(+)- and activity-dependent synaptic plasticity. Immunological localization of the LAT protein indicates it is present at synaptic connections of the larval neuromuscular junction (NMJ) and is enriched in presynaptic boutons. Basal synaptic transmission amplitude at the lat mutant NMJ is elevated 3- to 4-fold, and Ca2+ dependence of transmission is significantly reduced. Multiple forms of synaptic facilitation and posttetanic potentiation (PTP) are strongly depressed or absent at the mutant synapse. Our results suggest that LAT is a novel presynaptic protein with a role in the Ca2(+)-dependent synaptic modulation mechanisms necessary for behavioral plasticity. (+info)
Development of topography within song control circuitry of zebra finches during the sensitive period for song learning.
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Refinement of topographic maps during sensitive periods of development is a characteristic feature of diverse sensory and motor circuits in the nervous system. Within the neural system that controls vocal learning and behavior in zebra finches, axonal connections of the cortical nucleus lMAN demonstrate striking functional and morphological changes during vocal development in juvenile males. These circuits are uniquely important for song production during the sensitive period for vocal learning, and the overall size of these brain regions and their patterns of axonal connectivity undergo dramatic growth and regression during this time. Axonal connections to and from lMAN are topographically organized in adult males that have already learned song. We wondered whether the large-scale changes seen in lMAN circuitry during the time that vocal behavior is being learned and refined could be accompanied by the emergence of topographic mapping. However, results presented herein demonstrate that most of these song-control circuits show the same broad patterns of axonal connectivity between subregions of individual nuclei at the onset of song learning as seen in adult birds. Thus, coarse topographic organization is not dependent on the types of experience that are crucial for vocal learning. Furthermore, this maintenance of topographic organization throughout the period of song learning is clearly not achieved by maintenance of static axonal arbors. In fact, because the volumes of song-control nuclei are growing (or regressing), topography must be maintained by active remodeling of axonal arbors to adapt to the changes in overall size of postsynaptic targets. A salient exception to this pattern of conserved topography is the projection from lMAN to the motor cortical region RA: this pathway is diffusely organized at the onset of song learning but undergoes substantial refinement during early stages of song learning, suggesting that remodeling of axonal connections within this projection during the period of vocal learning may signify the production of increasingly refined vocal utterances. (+info)
Computer-based teaching of pathology at the Zagreb University School of Medicine.
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AIM: To review the experience gained in transferring USA computer-based teaching system of medical school pathology to Croatia. METHODS: Computer-based teaching program of pathology developed at the University of Kansas School of Medicine, Kansas City, Kansas, USA, was transferred to the University of Zagreb School of Medicine, Zagreb, Croatia. The experimental group of 49 students was enrolled into this computer-based program. Their performance was compared with that of 195 classmates enrolled in the standard course. Objective (performance on the examinations) and subjective data (students' interviews and written evaluations of the course) were analyzed. RESULTS: The computer program was operational 5 months from the inception of the transfer. It was well received by the students, even though many initially complained that it required more effort and a continuous commitment. The major problems concerned scheduling, reflecting various requirements i mposed on students by other departments teaching in parallel with the Pathology course. Objective data gathered so far indicate that the students enrolled in the computer-based program took the first midterm examination at a significantly higher rate than the rest of the class (p<0.001), and passed the examination with significantly better grades (p<0.001). CONCLUSION: Computer-based teaching programs can be readily transferred to other countries. Full implementation of the program, however, may require significant changes in the existing curriculum in the medical school to which such a program has been transferred or considerable modifications in the program adopted for transfer. It appears that the students enrolled in the computer-based program perform better than students in the standard pathology course. (+info)
Building peace from scratch: some theoretical and technological aspects.
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A peace-building process is based on activity, acceptance, understanding of political reality, communication, and empowerment. Acceptance means accepting everybody as he or she is and let each know it. This is at the heart of peace work, it is the prerequisite for effective communication, and includes accepting other even in cases of severe disagreement. Peace work requires both an understanding of political reality and the expression of one's own political opinion. Acceptance and the expression of political opinion are not at variance but complementary. Combining acceptance and understanding of the political context provides hope for real communication in which messages are both sent and received, with appreciation and interest. Empowerment implies overcoming of the feeling of powerlessness, often present in conflict by all sides and in all social groups. It includes recovery of self-respect and respect for others. Education and economic independence are important facets of the empowerment concept. Essential principles of peace-building process are responsibility, solidarity, cooperation, and nonviolence. Responsibility encompasses caring for human rights, the suffering of others, and for consequences of our own intended and unintended actions. Solidarity allows learning through listening and understanding. Even with the best intentions on both sides, cooperation may be difficult and painful. Nonviolence is a way of life. (+info)