Showing papers on "Encoding (memory) published in 2010"

Predictive, interactive multiple memory systems.

Abstract: Most lesion studies in animals, and neuropsychological and functional neuroimaging studies in humans, have focused on finding dissociations between the functions of different brain regions, for example in relation to different types of memory. While some of these dissociations can be questioned, particularly in the case of neuroimaging data, we start by assuming a "modal model" in which at least three different memory systems are distinguished: an episodic system (which stores associations between items and spatial/temporal contexts, and which is supported primarily by the hippocampus); a semantic system (which extracts combinations of perceptual features that define items, and which is supported primarily by anterior temporal cortex); and modality-specific perceptual systems (which represent the sensory features extracted from a stimulus, and which are supported by higher sensory cortices). In most situations however, behavior is determined by interactions between these systems. These interactions reflect the flow of information in both "forward" and "backward" directions between memory systems, where backward connections transmit predictions about the current item/features based on the current context/item. Importantly, it is the resulting "prediction error"--the difference between these predictions and the forward transmission of sensory evidence--that drives memory encoding and retrieval. We describe how this "predictive interactive multiple memory systems" (PIMMS) framework can be applied to human neuroimaging data acquired during encoding or retrieval phases of the recognition memory paradigm. Our novel emphasis is thus on associations rather than dissociations between activity measured in key brain regions; in particular, we propose that measuring the functional coupling between brain regions will help understand how these memory systems interact to guide behavior.

Facing the future: memory as an evolved system for planning future acts.

Abstract: All organisms capable of long-term memory are necessarily oriented toward the future. We propose that one of the most important adaptive functions of long-term episodic memory is to store information about the past in the service of planning for the personal future. Because a system should have especially efficient performance when engaged in a task that makes maximal use of its evolved machinery, we predicted that future-oriented planning would result in especially good memory relative to other memory tasks. We tested recall performance of a word list, using encoding tasks with different temporal perspectives (e.g., past, future) but a similar context. Consistent with our hypothesis, future-oriented encoding produced superior recall. We discuss these findings in light of their implications for the thesis that memory evolved to enable its possessor to anticipate and respond to future contingencies that cannot be known with certainty.

Method for erasure coding data across a plurality of data stores in a network

Abstract: An efficient method to apply an erasure encoding and decoding scheme across dispersed data stores that receive constant updates. A data store is a persistent memory for storing a data block. Such data stores include, without limitation, a group of disks, a group of disk arrays, or the like. An encoding process applies a sequencing method to assign a sequence number to each data and checksum block as they are modified and updated onto their data stores. The method preferably uses the sequence number to identify data set consistency. The sequencing method allows for self-healing of each individual data store, and it maintains data consistency and correctness within a data block and among a group of data blocks. The inventive technique can be applied on many forms of distributed persistent data stores to provide failure resiliency and to maintain data consistency and correctness.

Method and apparatus for distributed storage integrity processing

Abstract: A distributed storage integrity system in a dispersed storage network includes a scanning agent and a control unit. The scanning agent identifies an encoded data slice that requires rebuilding, wherein the encoded data slice is one of a plurality of encoded data slices generated from a data segment using an error encoding dispersal function. The control unit retrieves at least a number T of encoded data slices needed to reconstruct the data segment based on the error encoding dispersal function. The control unit is operable to reconstruct the data segment from at least the number T of the encoded data slices and generate a rebuilt encoded data slice from the reconstructed data segment. The scanning agent is located in a storage unit and the control unit is located in the storage unit or in a storage integrity processing unit, a dispersed storage processing unit or a dispersed storage managing unit.

Memory in microbes: quantifying history-Dependent behavior in a bacterium. - eScholarship

Abstract: Memory is usually associated with higher organisms rather than bacteria. However, evidence is mounting that many regulatory networks within bacteria are capable of complex dynamics and multi-stable behaviors that have been linked to memory in other systems. Moreover, it is recognized that bacteria that have experienced different environmental histories may respond differently to current conditions. These memory effects may be more than incidental to the regulatory mechanisms controlling acclimation or to the status of the metabolic stores. Rather, they may be regulated by the cell and confer fitness to the organism in the evolutionary game it participates in. Here, we propose that history-dependent behavior is a potentially important manifestation of memory, worth classifying and quantifying. To this end, we develop an information-theory based conceptual framework for measuring both the persistence of memory in microbes and the amount of information about the past encoded in history-dependent dynamics. This method produces a phenomenological measure of cellular memory without regard to the specific cellular mechanisms encoding it. We then apply this framework to a strain of Bacillus subtilis engineered to report on commitment to sporulation and degradative enzyme (AprE) synthesis and estimate the capacity of these systems and growth dynamics to 'remember' 10 distinct cell histories prior to application of a common stressor. The analysis suggests that B. subtilis remembers, both in short and long term, aspects of its cell history, and that this memory is distributed differently among the observables. While this study does not examine the mechanistic bases for memory, it presents a framework for quantifying memory in cellular behaviors and is thus a starting point for studying new questions about cellular regulation and evolutionary strategy.

Encoding method and system, decoding method and system

Abstract: A decoder, an encoder, a decoding method and an encoding method are provided. The encoding method includes receiving data; generating a set of first codewords by applying a first encoding process on the received data; and performing a second encoding process on a folded version of each first codeword to provide a set of second codewords, wherein a folded version of a first codeword is representative of a storage of the first codeword in a two dimensional memory space, wherein the second codeword comprises redundancy bits.

Improving Multi-Level NAND Flash Memory Storage Reliability Using Concatenated BCH-TCM Coding

Abstract: By storing more than one bit in each memory cell, multi-level per cell (MLC) NAND flash memories are dominating global flash memory market due to their appealing storage density advantage. However, continuous technology scaling makes MLC NAND flash memories increasingly subject to worse raw storage reliability. This paper presents a memory fault tolerance design solution geared to MLC NAND flash memories. The basic idea is to concatenate trellis coded modulation (TCM) with an outer BCH code, which can greatly improve the error correction performance compared with the current design practice that uses BCH codes only. The key is that TCM can well leverage the multi-level storage characteristic to reduce the memory bit error rate and hence relieve the burden of outer BCH code, at no cost of extra redundant memory cells. The superior performance of such concatenated BCH-TCM coding systems for MLC NAND flash memories has been well demonstrated through computer simulations. A modified TCM demodulation approach is further proposed to improve the tolerance to static memory cell defects. We also address the associated practical implementation issues in case of using either single-page or multi-page programming strategy, and demonstrate the silicon implementation efficiency through application-specific integrated circuit design at 65 nm node.

When two is too many: Collaborative encoding impairs memory

Abstract: Humans routinely encode and retrieve experiences in interactive, collaborative contexts Yet much of what we know about human memory comes from research on individuals working in isolation Some recent research has examined collaboration during retrieval, but not much is known about how collaboration during encoding affects memory We examined this issue Participants created episodes by elaborating on study materials alone or collaboratively, and they later performed a cued-recall task alone, with the study partner, or with a different partner (Experiment 1) Collaborative encoding impaired recall This counterintuitive outcome was found for both individual and group recall, even when the same partners collaborated across encoding and retrieval This impairment was significantly reduced, but persisted, when the encoding instructions encouraged free-flowing collaboration (Experiment 2) Thus, the collaborative-encoding deficit is robust in nature and likely occurs because collaborative encoding produces less effective cues for later retrieval

New perspectives on vierordt's law: memory-mixing in ordinal temporal comparison tasks

Abstract: Distortions in temporal memory can occur as a function of differences in signal modalities and/or by the encoding of multiple signal durations associated with different timing tasks into a single memory distribution – an effect referred to as “memory mixing”. Evidence for this type of memory distortion and/or categorization of signal durations as an explanation for changes in temporal context (e.g., duration ranges), as well as for Vierordt's law (e.g., overestimation of “short” durations and underestimation of “long” durations), can be studied by examining proactive interference effects from the previous trial(s). Moreover, we demonstrate that individual differences in the magnitude of this “memory-mixing” phenomenon are correlated with variation in reaction times for ordinal temporal comparisons as well as with sensitivity to feedback effects in the formation of duration-specific memory distributions.

Uplink control signal design for wireless system

Abstract: Transmission of uplink control message for a wireless system. The uplink control message may be encoded according to one of multiple possible schemes. The choice of encoding scheme may be made based on the control message size and/or based on the available transmission resources and/or based on the detection scheme used on the receiving end. A modulation scheme may also be selected based on such factors. CDM may be used for certain control messages. Block code encoding, such as Reed-Muller encoding may be used for certain control messages. Different transmission resources may be allocated for different control message uses. The encoding specifics may be selected to obtain a certain hamming distance and/or size of the encoded message or based on other factors.

Systems and methods for encoding information for storage in an electronic memory and for decoding encoded information retrieved from an electronic memory

Abstract: Method and system embodiments of the present invention are directed to encoding information in ways that are compatible with constraints associated with electrical-resistance-based memories and useful in other, similarly constrained applications, and to decoding the encoded information. One embodiment of the present invention encodes k information bits and writes the encoded k information bits to an electronic memory, the method comprising systematically encoding the k information bits to produce a vector codeword, with additional parity bits so that the codeword is resilient to bit-transition errors that may occur during storage of the codeword in, and retrieval of the codeword from, the electronic memory, ensuring that the codeword does not violate a weight constraint, and writing the codeword to the electronic memory.

Does survival processing enhance implicit memory

Abstract: Recent research has shown that human memory may have evolved to remember information that has been processed for the purpose of survival, more so than information that has been processed for other purposes, such as home-moving. We investigated this survival-processing advantage using both explicit and implicit memory tests. In Experiment 1, participants rated words in one of three scenarios: survival, pleasantness, and moving, followed by a timed stem-cued recall/stem-cued completion task. Items were completed more quickly in the survival scenario, as compared with the other two for the explicit task, but no differences were found across conditions in the implicit task. In Experiment 2, the implicit task was changed to concreteness judgments to encourage more conceptual processing. Again, the survival-processing advantage occurred in the explicit task (speeded item recognition), but not in the implicit task. These results suggest that a survival-processing advantage may benefit participants’ memory performance only during explicit retrieval.

Video encoding method for encoding division block, video decoding method for decoding division block, and recording medium for implementing the same

Abstract: Disclosed are a method of encoding a division block in video encoding and a method of decoding a division block in video decoding. An input picture is divided into encoding unit blocks. The encoding unit blocks are divided into sub-blocks. The sub-blocks are encoded by selectively using at least one of intra prediction encoding and inter prediction encoding. A decoding process is performed through a reverse process of the encoding method. When pixel values of an encoding unit block are encoded in video encoding, the flexibility in selecting an encoding mode is increased and the efficiency of encoding is increased.

Method and apparatus for encoding and decoding image by using large transformation unit

Abstract: Disclosed are an image encoding method and apparatus for encoding an image by grouping a plurality of adjacent prediction units into a transformation unit and transforming the plurality of adjacent prediction into a frequency domain, and an image decoding method and apparatus for decoding an image encoded by using the image encoding method and apparatus.

Different spatial memory systems are involved in small- and large-scale environments: evidence from patients with temporal lobe epilepsy

Abstract: Recent reports show that humans and animals do not acquire information about routes and object locations in the same way. In spatial memory, a specific sub-system is hypothesized to be involved in encoding, storing and recalling navigational information, and it is segregated from the sub-system devoted to small-scale environment. We assessed this hypothesis in a sample of patients treated surgically for intractable temporal lobe epilepsy. We found double dissociations between learning and recall of spatial positions in large space versus small space. These results strongly support the hypothesis that two segregate systems process navigational memory for large-scale environments and spatial memory in small-scale environments.

Sensory-specific clock components and memory mechanisms: Investigation with parallel timing.

Abstract: A challenge for researchers in the time-perception field is to determine whether temporal processing is governed by a central mechanism or by multiple mechanisms working in concert. Behavioral studies of parallel timing offer interesting insights into the question, although the conclusions fail to converge. Most of these studies focus on the number-of-clocks issue, but the commonality of memory mechanisms involved in time processing is often neglected. The present experiment aims to address a straightforward question: do signals from different modalities marking time intervals share the same clock and/or the same memory resources? To this end, an interval reproduction task involving the parallel timing of two sensory signals presented either in the same modality or in different modalities was conducted. The memory component was tested by manipulating the delay separating the presentation of the target intervals and the moment when the reproduction of one of these began. Results show that there is more variance when only visually marked intervals are presented, and this effect is exacerbated with longer retention delays. Finally, when there is only one interval to process, encoding the interval with signals delivered from two modalities helps to reduce variance. Taken together, these results suggest that the hypothesis stating that there are sensory-specific clock components and memory mechanisms is viable.

Adaptive memory: nature's criterion and the functionalist agenda.

Abstract: Memory researchers traditionally ignore function in favor of largely structural analyses. For example, it is well known that forming a visual image improves retention, and various proximate mechanisms have been proposed to account for the advantage (e.g., elaboration of the memory trace), but next to nothing is known about why memory evolved such sensitivities. Why did nature craft a memory system that is sensitive to imagery or the processing of meaning? Functional analyses are critical to progress in memory research for two main reasons: First, as in applied research, functional analyses provide the necessary criteria for measuring progress; second, there are good reasons to believe that modern cognitive processes continue to bear the imprint of ancestral selection pressures (i.e., cognitive systems are functionally designed). We review empirical evidence supporting the idea that memory evolved to enhance reproductive fitness; as a consequence, to maximize retention in basic and applied settings it is useful to develop encoding techniques that are congruent with the natural design of memory systems.

Progressive shape based encoding of video content within a swarm environment

Abstract: Embodiments are directed towards employing distributed computing concepts such as peer-to-peer processing to distribute across a plurality of peer client devices, or swarm, the computations of Shape Encoding Schemes (SES) for encoding digital video content. As more peer client devices receive the content, progressively more iterations of a SES encoding is performed on various frames within the video content, thereby improving the encoding of the overall video content. Optionally, such distributed progressive processing or swarming approach may include other encoding, such as scaling corrections, scene transitions corrections, and the like.

Backward recall and benchmark effects of working memory

Abstract: Working memory was designed to explain four benchmark memory effects: the word length effect, the irrelevant speech effect, the acoustic confusion effect, and the concurrent articulation effect. However, almost all research thus far has used tests that emphasize forward recall. In four experiments, we examine whether each effect is observable when the items are recalled in reverse order. Subjects did not know which recall direction would be required until the time of test, ensuring that encoding processes would be identical for both recall directions. Contrary to predictions of both the primacy model and the feature model, the benchmark memory effect was either absent or greatly attenuated with backward recall, despite being present with forward recall. Direction of recall had no effect on the more difficult conditions (e.g., long words, similar-sounding items, items presented with irrelevant speech, and items studied with concurrent articulation). Several factors not considered by the primacy and feature models are noted, and a possible explanation within the framework of the SIMPLE model is briefly presented.

Capacities of Lossy Bosonic Memory Channels

Abstract: We introduce a general model describing correlated noise effects in quantum optical communication via attenuating media. The memory effects account for the environment finite relaxation times, which are unavoidable in any realistic model. The use of a proper set of collective field variables allows us to unravel the memory, showing that the n-fold concatenation of the memory channel is unitarily equivalent to the direct product of n single-mode lossy bosonic channels. We then compute the ultimate (classical and quantum) transmission rates, showing their enhancement with respect to the memoryless case and proving that coherent state encoding is optimal.

Do objects in working memory compete with objects in perception

Abstract: It is generally assumed that "perceptual object" is the basic unit for processing visual information and that only a small number of objects can be either perceptually selected or encoded in working memory (WM) at one time. This raises the question whether the same resource is used when objects are selected and tracked as when they are held in WM. In two experiments, we measured dual-task interference between a memory task and a Multiple Object Tracking task. The WM tasks involve explicit, implicit, or no spatial processing. Our results suggest there is no resource competition between working memory and perceptual selection except when the WM task requires encoding spatial properties.

Transmitter quieting and null data encoding

Abstract: In one example, a method comprises encoding a set of frames of multimedia data, encoding null data for a period following the set of frames of multimedia data, modulating the encoded set of frames and the null data, wherein modulating the null data creates a null interval over the period, transmitting the encoded set of frames via a transmitter, and blanking the transmitter during the null interval.

The time course of working memory effects on visual attention

Abstract: Previous work has generated inconsistent results with regard to what extent working memory (WM) content guides visual attention. Some studies found effects of easy to verbalize stimuli, whereas others only found an influence of visual memory content. To resolve this, we compared the time courses of memory-based attentional guidance for different memory types. Participants first memorized a colour, which was either easy or difficult to verbalize. They then looked for an unrelated target in a visual search display and finally completed a memory test. One of the distractors in the search display could have the memorized colour. We varied the time between the to-be-remembered colour and the search display, as well as the ease with which the colours could be verbalized. We found that the influence of easy to verbalize WM content on visual search decreased with increasing time, whereas the influence of visual WM content was sustained. However, visual working memory effects on attention also decreased when the duration of visual encoding was limited by an additional task or when the memory item was presented only briefly. We propose that for working memory effects on visual attention to be sustained, a sufficiently strong visual representation is necessary.

Encoding Sequential Information in Vector Space Models of Semantics: Comparing Holographic Reduced Representation and Random Permutation

Abstract: Encoding information about the order in which words typically appear has been shown to improve the performance of high-dimensional semantic space models. This requires an encoding operation capable of binding together vectors in an order-sensitive way, and efficient enough to scale to large text corpora. Although both circular convolution and random permutations have been enlisted for this purpose in semantic models, these operations have never been systematically compared. In Experiment 1 we compare their storage capacity and probability of correct retrieval; in Experiments 2 and 3 we compare their performance on semantic tasks when integrated into existing models. We conclude that random permutations are a scalable alternative to circular convolution with several desirable properties.

A Spiking Neuron Model of Serial-Order Recall

Abstract: A Spiking Neuron Model of Serial-Order Recall Feng-Xuan Choo (fchoo@uwaterloo.ca) Chris Eliasmith (celiasmith@uwaterloo.ca) Center for Theoretical Neuroscience, University of Waterloo Waterloo, ON, Canada N2L 3G1 Abstract vectors such that the result is another vector that is similar to the original input vectors. Third, a binding operation (⊗) is used to combine vectors such that the result is a vector that is dissimilar to original vectors. Last, an approximate inverse operation (denoted with ∗ , such that A ∗ is the approximate in- verse of A) is needed so that previously bound vectors can be unbound. A ⊗ B ⊗ B ∗ ≈ A Vector symbolic architectures (VSAs) have been used to model the human serial-order memory system for decades. Despite their success, however, none of these models have yet been shown to work in a spiking neuron network. In an effort to take the first step, we present a proof-of-concept VSA-based model of serial-order memory implemented in a network of spiking neurons and demonstrate its ability to successfully encode and decode item sequences. This model also provides some insight into the differences between the cognitive processes of mem- ory encoding and subsequent recall, and establish a firm foun- dation on which more complex VSA-based models of memory can be developed. Keywords: Serial-order memory; serial-order recall; vector symbolic architectures; holographic reduced representation; population coding; LIF neurons; neural engineering frame- work Just like addition and multiplication, the VSA operations are associative, commutative, and distributive. The class of VSA used in this model is the Holographic Reduced Representation (HRR) (Plate, 2003). In this repre- sentation, each element of an HRR vector is chosen from a normal distribution with a mean of 0, and a variance of 1/n where n is the number of elements there are in the vector. The standard addition operator is used to perform the superposi- tion operation, and the circular convolution operation is used to perform the binding operation. The circular convolution of two vectors can be efficiently computed by utilizing the Fast Fourier Transform (FFT) algorithm: Introduction The human memory system is able to perform a multitude of tasks, one of which is the ability to remember and recall sequences of serially ordered items. In human serial recall experiments, subjects are presented items at a fixed interval, typically in the range of two items per second up to one item every 4 seconds. After the entire sequence has been presented the subjects are then asked to recall the items presented to them, either in order (serial recall), or in any order the sub- ject desires (free recall). Plotting the recall accuracy of the subjects, experimenters often obtain a graph with a distinc- tive U-shape. This unique shape arises from what is known as the primacy and recency effects. The primacy effect refers to the increase in recall accuracy the closer the item is to the start of the sequence, and the recency effect refers to the same increase in recall accuracy as the item gets closer to the end of the sequence. Many models have been proposed to explain this peculiar behaviour in the recall accuracy data. Here we will concen- trate on one class of models which employ vector symbolic architectures (VSAs) to perform the serial memory and re- call. Using VSAs to perform serial memory tasks would be insufficient however, if the VSA-based model cannot be im- plemented in spiking neurons, and thus, cannot be used to explain what the brain is actually doing. In this paper, we thus present a proof-of-concept VSA-based model of serial recall implemented using spiking neurons. x ⊗ y = F −1 ( F (x) F (y)), where F and F −1 are the FFT and inverse FFT operations respectively, and is the element-wise multiplication of the two vectors. The circular convolution operation, unlike the standard convolution operation, does not change the dimen- sionality of the result vector. This makes the HRR extremely suitable for a neural implementation because it means that the dimensionality of the network remains constant regardless of the number of operations performed. The VSA-based Approach to Serial Memory There are multiple ways in which VSAs can be used to encode serially ordered items into a memory trace. The CADAM model (Liepa, 1977) provides a simple example of how a sequence of items can be encoded as a single mem- ory trace. In the CADAM model, the sequence containing the items A, B, and C would be encoded as in single memory trace, M ABC as follows: M A = A M AB = A + A ⊗ B Vector Symbolic Architecture There are four core features of vector symbolic architectures. First, information is represented by randomly chosen vectors that are combined in a symbol-like manner. Second, a super- position operation (here denoted with a +) is used to combine M ABC = A + A ⊗ B + A ⊗ B ⊗ C The model presented in this paper, however, takes inspira- tion from behavioural data obtained from macaque monkeys. This data suggests that each sequence item is encoded using