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941.
942.
We explored whether information processed subconsciously in blindsight is qualitatively different from normal conscious processing. On each trial the blindsight patient GY was presented with a square-wave grating either in an upper or lower quadrant of his visual field and was asked to report the opposite of its location (e.g. to say 'Up' if it was in the lower quadrant). We found that while GY was able to follow these exclusion instructions in his normal field, he tended to erroneously respond with the real location when the grating appeared in his blind field. Remarkably, his error rate actually increased with increasing grating contrast in his blind field. The interpretation of these results does not rely on subjective reports and thus cannot be criticized on the grounds that subjective reports are unreliable. We conclude that blindsight is unlike normal conscious vision. 相似文献
943.
Parametric induction of animacy experience 总被引:2,自引:1,他引:1
Graphical displays of simple moving geometrical figures have been repeatedly used to study the attribution of animacy in human observers. Yet little is known about the relevant movement characteristics responsible for this experience. The present study introduces a novel parametric research paradigm, which allows for the experimental control of specific motion parameters and a predictable influence on the attribution of animacy. Two experiments were conducted using 3D computer animations of one or two objects systematically introducing variations in the following aspects of motion: directionality, discontinuity and responsiveness. Both experiments further varied temporal kinematics. Results showed that animacy experience increased with the time a moving object paused in the vicinity of a second object and with increasing complexity of interaction between the objects (approach and responsiveness). The experience of animacy could be successfully modulated in a parametric fashion by the systematic variation of comparably simple differential movement characteristics. 相似文献
944.
Heshka J Palleschi C Wilson B Brehaut J Rutberg J Etchegary H Langlois N Rodger M Wells PS 《Journal of genetic counseling》2008,17(3):288-296
Very few studies have examined the impact of genetic testing for thrombophilia on health behaviours, perceptions of control over risk factors for venous thromboembolism, or health services utilization. Through a postal questionnaire we compared first degree relatives with thrombophilia (carriers) most of whom had received counseling, to those without (non-carriers) with respect to: (a) perceived causes of venous thromboembolism; (b) perceived control; (c) health behaviour changes; and (d) use of health care services. 44/51 for carriers and 26/47 for non-carriers completed questionnaires. Carriers were more likely to believe their risk of venous thromboembolism 'is a little higher' or 'much higher' than average (p < 0.001) but some continued to believe their risk 'is the same as' or 'lower than' average. 16%-32% of carriers did not recognize major risk factors. Stress, worry, or depression, negative attitude, and over-exertion were over-interpreted as risks. 37.2% did not appreciate that thrombophilia increases risk. Behaviour changes were uncommon. There is a need for research on education and strategies to improve knowledge in thrombophilia carriers. 相似文献
945.
We report a family with an extensive history of colon cancer consistent with hereditary nonpolyposis colorectal cancer (HNPCC).
A specific disease causing mutation was identified in affected individuals; p.W714X MLH1 mutation. Given the very young age of onset of cancer in some affected family members, with the youngest affected individual
being 19 years of age, genetic counseling was recommended to children as young as 9 years. Ethical issues arose when affected
families requested genetic testing for their underage children. Here we describe and debate the value of offering molecular
testing for this adult onset disorder to several children in this particular family. We also examine possible molecular causes
for the very young age of onset in some family members. 相似文献
946.
Gelinas JN Tenorio G Lemon N Abel T Nguyen PV 《Learning & memory (Cold Spring Harbor, N.Y.)》2008,15(5):281-289
Activation of β-adrenergic receptors (β-ARs) enhances hippocampal memory consolidation and long-term potentiation (LTP), a likely mechanism for memory storage. One signaling pathway linked to β-AR activation is the cAMP-PKA pathway. PKA is critical for the consolidation of hippocampal long-term memory and for the expression of some forms of long-lasting hippocampal LTP. How does β-AR activation affect the PKA-dependence, and persistence, of LTP elicited by distinct stimulation frequencies? Here, we use in vitro electrophysiology to show that patterns of stimulation determine the temporal phase of LTP affected by β-AR activation. In addition, only specific patterns of stimulation recruit PKA-dependent LTP following β-AR activation. Impairments of PKA-dependent LTP maintenance generated by pharmacologic or genetic deficiency of PKA activity are also abolished by concurrent activation of β-ARs. Taken together, our data show that, depending on patterns of synaptic stimulation, activation of β-ARs can gate the PKA-dependence and persistence of synaptic plasticity. We suggest that this may allow neuromodulatory receptors to fine-tune neural information processing to meet the demands imposed by numerous synaptic activity profiles. This is a form of “metaplasticity” that could control the efficacy of consolidation of hippocampal long-term memories.The hippocampus importantly contributes to memory function in the mammalian brain (Zola-Morgan et al. 1986; Eichenbaum et al. 1990; Otto and Eichenbaum 1992; Phillips and LeDoux 1992; Remondes and Schuman 2004). It has reciprocal connections with numerous cortical areas, including those responsible for high-level integration of spatial and contextual data from the external environment (Lavenex and Amaral 2000). As such, the hippocampus is well positioned to receive and survey a broad range of information and select behaviorally salient data for long-term storage. Activity-dependent enhancement of hippocampal synaptic strength can store information carried in patterns of afferent neural activity (Bliss and Collingridge 1993; Moser et al. 1998; Nathe and Frank 2003; Whitlock et al. 2006). Substantial evidence suggests that long-term potentiation (LTP) of synaptic strength plays important roles in the formation of long-term memory (LTM) (Doyere and Laroche 1992; Bourtchuladze et al. 1994; Abel and Lattal 2001; Genoux et al. 2002). As such, mechanistic studies of LTP have shed valuable light on how the mammalian brain stores new information.The hippocampus receives dense noradrenergic projections from the locus coeruleus, a brain structure that can influence many vital brain functions, including attention, sleep, arousal, mood regulation, learning, and memory (Berridge and Waterhouse 2003). Both α- and β-adrenergic receptor subtypes are present on hippocampal neurons (Morrison and Foote 1986; Berridge and Waterhouse 2003), and noradrenaline (NA) acts on hippocampal β-adrenergic receptors (β-ARs) to facilitate the retention and recall of memory (Izquierdo et al. 1998; Ji et al. 2003; Murchison et al. 2004). In humans, stimulation of the noradrenergic neuromodulatory system enhances memory for emotional stimuli, and inhibition of β-ARs prevents this memory enhancement (Cahill et al. 1994; van Stegeren et al. 1998; O’Carroll et al. 1999).Consistent with the notion that selective enhancement of LTM may occur following β-AR activation, stimulation of β-ARs can also facilitate the persistence of LTP. In areas CA3 and CA1, β-AR activation facilitates the induction of long-lasting LTP when paired with certain patterns of electrical stimulation (Huang and Kandel 1996; Gelinas and Nguyen 2005). However, the mechanisms by which different patterns of stimulation control synaptic responsiveness to β-AR activation are unclear.β-ARs couple to guanine-nucleotide-binding regulatory Gs proteins to stimulate adenylyl cyclase activity and increase intracellular cAMP (Seeds and Gilman 1971; Maguire et al. 1977). A main target of cAMP signaling is activation of cAMP-dependent protein kinase (PKA), a kinase that is required for some forms of long-lasting LTP and for consolidation of hippocampal LTM (Frey et al. 1993; Abel et al. 1997; Nguyen and Woo 2003). Interestingly, the PKA-dependence of hippocampal LTP displays plasticity: Specific temporal patterns of synaptic stimulation, such as repeated and temporally spaced 100-Hz stimulation, elicit LTP that requires PKA for its expression (Woo et al. 2003). Also, spatial “enrichment” can increase the PKA-dependence of LTP in mice, and this is correlated with improved hippocampal memory function (Duffy et al. 2001). However, it is unclear whether activation of β-ARs can critically gate the PKA-dependence of LTP. In this study, we examine the effects of β-AR activation on LTP generated by various patterns of afferent stimulation in area CA1 of the hippocampus, and we determine the role of PKA in these β-AR-modulated forms of LTP. 相似文献
947.
One retrieval trial induces reconsolidation in an appetitive learning paradigm in honeybees (Apis mellifera) 总被引:1,自引:0,他引:1
Combining memory retrieval with the application of a protein synthesis-inhibitor leads to an amnestic effect that is referred to as the reconsolidation phenomenon. Several behavioural studies demonstrate that only a few or weak retrieval trials (that do not result in significant extinction) lead to this phenomenon. In contrast, many trials (that result in significant extinction) combined with a protein synthesis inhibitor result in an inhibition of the extinction memory. Based on these findings it was suggested that extinction is the boundary condition for reconsolidation: when extinction is induced the consolidation of the extinction memory is the dominant process. Recently we were not able to confirm this hypothesis in the honeybee (Apis mellifera): We did not find the reconsolidation phenomenon after one retrieval trial, but demonstrated reconsolidation after five retrieval trials that led to extinction. To exclude that this observation resembles a special case in insects we here wanted to know if one retrieval trial induces reconsolidation as it has been demonstrated before in many other species. To do so we used experimental parameters that had been used before to demonstrate consolidation in the honeybee with the exception that this time the protein synthesis-inhibitor was applied 1 h after one memory retrieval instead after acquisition. We thereby demonstrate the reconsolidation phenomenon after one retrieval trial but only when using the doubled dose of protein synthesis-inhibitor that has been used to inhibit consolidation. 相似文献
948.
Vaglenova J Parameshwaran K Suppiramaniam V Breese CR Pandiella N Birru S 《Neurobiology of learning and memory》2008,90(3):527-536
Nicotine, the main psychoactive ingredient in tobacco, readily crosses the placental barrier to cause growth and neurobehavioral abnormalities in the offspring. The current study was designed to assess whether nicotinic action causes long lasting teratogenic effects and synaptic dysfunctions. Pregnant Sprague-Dawley rats were infused with nicotine via osmotic minipumps at a dose of 6 mg/kg/day corresponding to the dose receiving during heavy smoking. A battery of behavioral tests and electrophysiological experiments were performed during specific postnatal periods. A spectrum of developmental and behavioral modifications in adolescent, young-adult and aged animals resulted after prenatal nicotine exposure. The potentially teratogenic effect of nicotine was clearly demonstrated in both genders by changes in developmental reflexes, exploratory and novelty seeking behavior, as well as a higher level of anxiety, and changes in individual and group responses in learning and memory. Most of the behavioral abnormalities were transitional with advancing age (6 months), although cognitive deficits measured by a two-way active avoidance task were long-lasting for male rats. Electrophysiological studies show decreased excitatory postsynaptic responses (mEPSCs) mediated by AMPA receptors in the hippocampus. These results suggest that teratogenic effect of nicotine on cognition is age and gender-specific, long-lasting and associated with AMPA receptor function. 相似文献
949.
950.