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Associative Memory (associative + memory)
Selected AbstractsComplex-valued multidirectional associative memoryELECTRICAL ENGINEERING IN JAPAN, Issue 1 2007Masaki Kobayashi Abstract Hopfield model is a representative associative memory. It was improved to Bidirectional Associative Memory (BAM) by Kosko and to Multidirectional Associative Memory (MAM) by Hagiwara. They have two layers or multilayers. Since they have symmetric connections between layers, they ensure convergence. MAM can deal with multiples of many patterns, such as (x1,x2,,), where xm is the pattern on layer m. Copyright © 2004 Wiley Periodicals, Inc. Noest, Hirose, and Nemoto proposed complex-value Hopfield model. Lee proposed complex-valued Bidirectional Associative Memory. Zemel proved the rotation invariance of complex-valued Hopfield model. It means that the rotated pattern in also stored. In this paper, the complex-valued Multidirectional Associative Memory is proposed. The rotation invariance is also proved. Moreover it is shown by computer simulation that the differences of angles of given patterns are automatically reduced. At first we define complex-valued Multidirectional Associative Memory. Then we define the energy function of network. With the energy function, we prove that the network ensures convergence. Next, we define the learning law and show the characteristic of recall process. The characteristic means that the differences of angles of given patterns are automatically reduced. Especially we prove the following theorem. In the case that only a multiple of patterns is stored, if patterns with different angles are given to each layer, the differences are automatically reduced. Finally, we investigate whether the differences of angles influence the noise robustness. It is found to reduce the noise robustness, because the input to each layer becomes small. We show this by computer simulations. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(1): 39,45, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20387 [source] Exploring consumer knowledge structures using associative network analysisPSYCHOLOGY & MARKETING, Issue 4 2010Thorsten A. Teichert This paper offers a new perspective on consumer knowledge analysis that combines Human Associative Memory (HAM) models from cognitive psychology with network analytic approaches in order to gain deeper insights into consumers" mental representations, such as brand images. An illustrative case study compares the associative networks of a manufacturer brand with a retail brand and is used to demonstrate the application and interpretation of various network measures. Network analysis is conducted on three levels: Node-level analysis yields insights about salient brand image components that can be affected through short-term marketing activities. Group-level analysis is concerned with brand image dimensions that characterize a brand and can be strategically influenced in the medium term. Finally, network-level analysis examines the network structure as a whole, drawing parallels to brand imagery, which needs to be managed over the long term. Management implications are derived and suggestions for further research are provided. © 2010 Wiley Periodicals, Inc. [source] Peptide signaling paths related to intoxication, memory and addictionADDICTION BIOLOGY, Issue 3 2000William E. M. Lands Many peptides bind to G protein-coupled receptors and activate intracellular signaling paths for adaptive cellular responses. The components of these paths can be affected by signals from other neurotransmitters to produce overall integrated results not easily predicted from customary a priori considerations. This intracellular cross-talk among signaling paths provides a "filter" through which long-term tonic signals affect short-term phasic signals as they progress toward the nucleus and induce long-term adaptation of gene expression which provide enduring attributes of acquired memories and addictions. Peptides of the PACAP family provide intracellular signaling that involves kinases, scaffolding interactions, Ca2 + mobilization, and gene expression to facilitate development of tolerance to alcohol and development of associative memories. The peptide-induced enhancement of NMDA receptor responses to extracellular glutamate also may increase behavioral sensitization to the low doses of alcohol that occur at the onset of each bout of drinking. Because many gene products participate in each signaling path, each behavioral response to alcohol is a polygenic process of many steps with no single gene product sufficient to interpret fully the adaptive response to alcohol. Different susceptibility of individuals to alcohol addiction may be a cumulative result of small differences among the many signaling components. Understanding this network of signals may help interpret future "magic bullets" proposed to treat addiction. [source] Detection of novelty, but not memory of spatial habituation, is associated with an increase in phosphorylated cAMP response element-binding protein levels in the hippocampusHIPPOCAMPUS, Issue 1 2004Milena Winograd Abstract There is a growing body of evidence showing that the formation of associative memories is associated with an increase in phosphorylated cAMP response element-binding protein (pCREB) levels. We recently reported increased pCREB levels in the rat hippocampus after an exploration to a novel environment. In the present work, we studied whether this increment in CREB activation is associated with the formation of memory of habituation to a novel environment or with the detection of novelty. Rats were submitted to consecutive open field sessions at 3-h intervals. Measurement of the hippocampal pCREB level, carried out 1 h after each training session, showed that (1) it did not increase when rats explored a familiar environment; (2) it did not increase after a reexposure that improves the memory of habituation; (3) it increased after a brief novel exploration unable to form memory of habituation; and (4) it increased in amnesic rats for spatial habituation. Taken as a whole, our results suggest that the elevated pCREB level after a single open field exploration is not associated with the memory formation of habituation. It is indeed associated with the detection of a novel environment. © 2003 Wiley-Liss, Inc. [source] Semantic Retrieval in DNA-Based Memories with Gibbs Energy ModelsBIOTECHNOLOGY PROGRESS, Issue 1 2006Andrew Neel At least three types of associative memories based on DNA-affinity have been proposed. Previously, we have quantified the quality of retrieval of genomic and abiotic information in simulation by comparison to state-of-the-art symbolic methods available, such as LSA (Latent Semantic Analysis). Their performance is poor when the evaluation criterion for DNA-affinity is a simple approximation of the Gibbs energy that governs duplex formation for retrievals. Here, we use a more realistic approximation of the Gibbs energy to improve semantic retrievals in DNA memories. Their performance is much closer to that of LSA, according to human expert ratings. With more realistic approximations of DNA affinity, performance is expected to improve for other, more adaptive associative memories with compaction in silico, and even more so with actual DNA molecules in vitro. [source] Emergence of long-term memory for conditioned aversion in the rat fetusDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2004Nadčge Gruest Abstract Pregnant rats were subjected to garlic essential oil as the conditioned stimulus and 45 min later to LiCl as the unconditioned stimulus either on embryonic Days 15 and 16 (E15 and E16) or on 18 and 19 (E18 and E19). Control dams received only garlic, LiCl, or water. Progenies were tested on garlic drinking 6 weeks after the exposure to the stimuli via the mothers. In the E18 to 19 group, rats that were exposed to paired garlic,LiCl expressed a significant aversion for garlic. In the E15 to 16 group, no significant differences appeared between subgroups. These results confirm that an associative memory can be established before birth and suggests that this ability potentially emerges in a short time window of 3 days at the end of gestation. Moreover, it appears that a long-term memory can be acquired in utero and retained to be expressed postnatally when animals are autonomous. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 189,198, 2004. [source] Complex-valued multidirectional associative memoryELECTRICAL ENGINEERING IN JAPAN, Issue 1 2007Masaki Kobayashi Abstract Hopfield model is a representative associative memory. It was improved to Bidirectional Associative Memory (BAM) by Kosko and to Multidirectional Associative Memory (MAM) by Hagiwara. They have two layers or multilayers. Since they have symmetric connections between layers, they ensure convergence. MAM can deal with multiples of many patterns, such as (x1,x2,,), where xm is the pattern on layer m. Copyright © 2004 Wiley Periodicals, Inc. Noest, Hirose, and Nemoto proposed complex-value Hopfield model. Lee proposed complex-valued Bidirectional Associative Memory. Zemel proved the rotation invariance of complex-valued Hopfield model. It means that the rotated pattern in also stored. In this paper, the complex-valued Multidirectional Associative Memory is proposed. The rotation invariance is also proved. Moreover it is shown by computer simulation that the differences of angles of given patterns are automatically reduced. At first we define complex-valued Multidirectional Associative Memory. Then we define the energy function of network. With the energy function, we prove that the network ensures convergence. Next, we define the learning law and show the characteristic of recall process. The characteristic means that the differences of angles of given patterns are automatically reduced. Especially we prove the following theorem. In the case that only a multiple of patterns is stored, if patterns with different angles are given to each layer, the differences are automatically reduced. Finally, we investigate whether the differences of angles influence the noise robustness. It is found to reduce the noise robustness, because the input to each layer becomes small. We show this by computer simulations. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(1): 39,45, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20387 [source] Shapes of nonmonotonic activation functions in a chaotic neural network associative memory model and its evaluationELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 3 2008Masanao Obayashi Abstract The purpose of this paper is to investigate the performance of the associative memory model using Aihara's chaotic neural network with different activation functions. Sigmoid function, a monotonic function, was used in Aihara's original model. However, in the static associative memory, it is reported that the storage capacity of the network is improved when a nonmonotonic function is used as the activation function. To improve the associative ability of chaotic neural network, kinds of nonmonotonic functions have been proposed to serve as activation function. This paper investigates their difference as to retrieval ability, and proposes an advanced nonmonotonic function. By computer simulation, we discuss what kind of shape is good regarding improving the associative ability of chaotic neural network. © 2008 Wiley Periodicals, Inc. Electron Comm Jpn, 91(3): 22, 27, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10070 [source] Selective lesions of basal forebrain cholinergic neurons produce anterograde and retrograde deficits in a social transmission of food preference task in ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2002Anna Vale-Martínez Abstract We examined the performance of Long-Evans rats with 192 IgG-saporin lesions of the medial septum/vertical limb of the diagonal band (MS/VDB) or nucleus basalis magnocellularis/substantia innominata (NBM/SI), which removed cholinergic projections mainly to hippocampus or neocortex, respectively. We studied the effects of these lesions on anterograde and retrograde memory for a natural form of hippocampal-dependent associative memory, the social transmission of food preference. In a study of anterograde memory, MS/VDB lesions did not affect the immediate, 24-h or 3-week retention of the task. In contrast, NBM/SI lesions severely impaired immediate and 24-h retention. In a study of retrograde memory in which rats acquired the food preference 5 days or 1 day before surgery and they were tested 10,11 days after surgery, MS/VDB-lesioned rats showed striking memory deficits for the preference acquired at a long delay (5 days) before surgery, although all lesioned rats exhibited poorer retention on both retest sessions than on their pretest performance. Subsequent testing of new anterograde learning in these rats revealed no disrupting effects of lesions on a standard two-choice test. When rats were administered a three-choice test, in which the target food was presented along with two more options, NBM/SI-lesioned rats were somewhat impaired on a 24-h retention test. These results provide evidence that NBM/SI and MS/VDB cholinergic neurons are differentially involved in a social memory task that uses olfactory cues, suggesting a role for these neurons in acquisition and consolidation/retrieval of nonspatial declarative memory. [source] Novel stability criteria for bidirectional associative memory neural networks with time delaysINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 5 2002Xiaofeng Liao Abstract In this paper, the bidirectional associative memory (BAM) neural network with axonal signal transmission delay is considered. This model is also referred to as a delayed dynamic BAM model. By combining a number of different Lyapunov functionals with the Razumikhin technique, some sufficient conditions for the existence of a unique equilibrium and global asymptotic stability of the network are derived. These results are fairly general and can be easily verified. Besides, the approach for the analysis allows one to consider several different types of activation functions, including piecewise linear sigmoids with bounded activations as well as C1 -smooth sigmoids. It is believed that these results are significant and convenient in the design and applications of BAM neural networks. Copyright © 2002 John Wiley & Sons, Ltd. [source] Storage of linguistic information in a continuous classifying associative memoryINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 6 2002Antonio B. Bailón In this article, we analyze the use of the continuous classifying associative memory (CCLAM) to store linguistic information. Freedom in the choice of the functions that control the operation of the CCLAM equip this memory with the capacity to adapt to different information storage and recovery needs. We begin with the problem of storing linguistic terms by memorizing the patterns formed by the degrees of compatibility with these terms. After that, the problem of storing linguistic rules is discussed. Let us remark that in these cases not a single CCLAM is used, but rather a set of them connected in suitable structured ways. © 2002 Wiley Periodicals, Inc. [source] Continuous classifying associative memoryINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 4 2002Antonio B. Bailón In this article we present the so-called continuous classifying associative memory, able to store continuous patterns avoiding the problems of spurious states and data dependency. This is a memory model based on our previously developed classifying associative memory, which enables continuous patterns to be stored and recovered. We will also show that the behavior of this continuous classifying associative memory may be adjusted to some predetermined goals by selecting some internal operating functions. © 2002 Wiley Periodicals, Inc. [source] Neuropsychological components of intellectual disability: the contributions of immediate, working, and associative memoryJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 5 2010Jamie O. Edgin Abstract Background Efficient memory functions are important to the development of cognitive and functional skills, allowing individuals to manipulate and store information. Theories of memory have suggested the presence of domain-specific (i.e. verbal and spatial) and general processing mechanisms across memory domains, including memory functions dependent on the prefrontal cortex (PFC) and the hippocampus. Comparison of individuals who have syndromes associated with striking contrasts in skills on verbal and spatial tasks [e.g. Down syndrome (DS) and Williams syndrome (WS)] allows us to test whether or not these dissociations may extend across cognitive domains, including PFC and hippocampal memory processes. Methods The profile of memory function, including immediate memory (IM), working memory (WM) and associative memory (AM), was examined in a sample of adolescents and young adults with DS (n = 27) or WS (n = 28), from which closely CA- and IQ-matched samples of individuals with DS (n = 18) or WS (n = 18) were generated. Relations between memory functions and IQ and adaptive behaviour were also assessed in the larger sample. Results Comparisons of the two matched groups indicated significant differences in verbal IM (DS < WS), spatial IM (DS > WS) and spatial and verbal AM (DS > WS), but no between-syndrome differences in WM. For individuals with DS, verbal IM was the most related to variation in IQ, and spatial AM related to adaptive behaviour. The pattern was clearly different for individuals with WS. Verbal and spatial AM were the most related to variation in IQ, and verbal WM related to adaptive behaviour. Conclusions These results suggest that individuals with these two syndromes have very different patterns of relative strengths and weaknesses on memory measures, which do not fully mirror verbal and spatial dissociations. Furthermore, different patterns of memory dysfunction relate to outcome in individuals with each syndrome. [source] | |||||||||||||