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hierarchical temporal memory

Carlo De Lillo, Melissa Kirby, Daniel Poole
Immediate serial spatial recall measures the ability to retain sequences of locations in short-term memory and is considered the spatial equivalent of digit span. It is tested by requiring participants to reproduce sequences of movements performed by an experimenter or displayed on a monitor. Different organizational factors dramatically affect serial spatial recall but they are often confounded or underspecified. Untangling them is crucial for the characterization of working-memory models and for establishing the contribution of structure and memory capacity to spatial span...
2016: Frontiers in Psychology
Anna Dora Manca, Mirko Grimaldi
Speech sound perception is one of the most fascinating tasks performed by the human brain. It involves a mapping from continuous acoustic waveforms onto the discrete phonological units computed to store words in the mental lexicon. In this article, we review the magnetoencephalographic studies that have explored the timing and morphology of the N1m component to investigate how vowels and consonants are computed and represented within the auditory cortex. The neurons that are involved in the N1m act to construct a sensory memory of the stimulus due to spatially and temporally distributed activation patterns within the auditory cortex...
2016: Frontiers in Psychology
Na-Yeon Jung, Sang Won Seo, Heejin Yoo, Jin-Ju Yang, Seongbeom Park, Yeo Jin Kim, Juyoun Lee, Jin San Lee, Young Kyoung Jang, Jong Min Lee, Sung Tae Kim, Seonwoo Kim, Eun-Joo Kim, Duk L Na, Hee Jin Kim
We aimed to categorize subjective memory impairment (SMI) individuals based on their patterns of cortical thickness and to propose simple models that can classify each subtype. We recruited 613 SMI individuals and 613 age- and gender-matched normal controls. Using hierarchical agglomerative cluster analysis, SMI individuals were divided into 3 subtypes: temporal atrophy (12.9%), minimal atrophy (52.4%), and diffuse atrophy (34.6%). Individuals in the temporal atrophy (Alzheimer's disease-like atrophy) subtype were older, had more vascular risk factors, and scored the lowest on neuropsychological tests...
August 20, 2016: Neurobiology of Aging
Yuwei Cui, Subutar Ahmad, Jeff Hawkins
The ability to recognize and predict temporal sequences of sensory inputs is vital for survival in natural environments. Based on many known properties of cortical neurons, hierarchical temporal memory (HTM) sequence memory recently has been proposed as a theoretical framework for sequence learning in the cortex. In this letter, we analyze properties of HTM sequence memory and apply it to sequence learning and prediction problems with streaming data. We show the model is able to continuously learn a large number of variableorder temporal sequences using an unsupervised Hebbian-like learning rule...
September 14, 2016: Neural Computation
Tomoki Kurikawa, Kunihiko Kaneko
In the brain, external objects are categorized in a hierarchical way. Although it is widely accepted that objects are represented as static attractors in neural state space, this view does not take account interaction between intrinsic neural dynamics and external input, which is essential to understand how neural system responds to inputs. Indeed, structured spontaneous neural activity without external inputs is known to exist, and its relationship with evoked activities is discussed. Then, how categorical representation is embedded into the spontaneous and evoked activities has to be uncovered...
2016: PloS One
Han Kyu Na, Dae Ryong Kang, Sungsoo Kim, Sang Won Seo, Kenneth M Heilman, Young Noh, Duk L Na
Recently, we reported that earlier stages of Alzheimer's disease (AD) can be categorized into 3 following anatomical subtypes using a hierarchical cluster analysis of cortical thickness across the entire brain: medial temporal-dominant (MT), parietal-dominant (P), and diffuse atrophy (D). The goal of this study was to investigate the rates of cognitive decline in these anatomical subtypes. Of the patients included in the prior study, 100 AD patients (MT, n = 36; P, n = 20; D, n = 44) who underwent follow-up neuropsychological assessments over a 3-year period were included...
August 12, 2016: Neurobiology of Aging
Chiara Cerami, Alessandra Dodich, Giada Lettieri, Sandro Iannaccone, Giuseppe Magnani, Alessandra Marcone, Luigi Gianolli, Stefano F Cappa, Daniela Perani
BACKGROUND: The diagnosis of probable behavioral variant of fronto-temporal dementia (bvFTD) according to current criteria requires the imaging evidence of frontal and/or anterior temporal atrophy or hypoperfusion/hypometabolism. Different variants of this pattern of brain involvement may, however, be found in individual cases, supporting the presence of heterogeneous phenotypes. OBJECTIVE: We examined in a case-by-case approach the FDG-PET metabolic patterns of patients fulfilling clinical criteria for probable bvFTD, assessing the presence and frequency of specific FDG-PET features...
October 2016: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
Yuji Naya
Declarative memories are our so-called daily language memories, which we are able to describe or explicitly experience through the act of remembering. This conscious recollection makes it possible for us to think about the future based on our previous experience (episodic memory) and knowledge (semantic memory). This cognitive function is substantiated by the medial temporal lobe (MTL), a hierarchically organized complex in which the perirhinal cortex and parahippocampal cortex provide item and context information to the hippocampus via the entorhinal cortex, and the hippocampus plays the main role in association and recollection...
July 11, 2016: Neuroscience Research
Shu-Hui Lee, James R Booth, Tai-Li Chou
Previous research has shown that left posterior middle temporal gyrus (pMTG) is a core node in the semantic network, and cross-sectional studies have shown that activation in this region changes developmentally and is related to skill measured concurrently. However, it is not known how functional connectivity with this region changes developmentally, and whether functional connectivity is related to future gains in reading. We conducted a longitudinal functional magnetic resonance imaging (fMRI) study in 30 typically developing children (aged 8-15) to examine whether initial brain measures, including activation and connectivity, can predict future behavioral improvement in a semantic judgment task...
July 1, 2016: NeuroImage
Renante Rondina, Kaitlin Curtiss, Jed A Meltzer, Morgan D Barense, Jennifer D Ryan
Episodic memories are comprised of details of "where" and "when"; spatial and temporal relations, respectively. However, evidence from behavioural, neuropsychological, and neuroimaging studies has provided mixed interpretations about how memories for spatial and temporal relations are organised-they may be hierarchical, fully interactive, or independent. In the current study, we examined the interaction of memory for spatial and temporal relations. Using explicit reports and eye-tracking, we assessed younger and older adults' memory for spatial and temporal relations of objects that were presented singly across time in unique spatial locations...
May 16, 2016: Memory
Kenichi Ota, Naoya Oishi, Kengo Ito, Hidenao Fukuyama
BACKGROUND: Prediction of progression to Alzheimer's disease (AD) in amnestic mild cognitive impairment (MCI) is challenging because of its heterogeneity. OBJECTIVE: To evaluate a stratification method on different cohorts and to investigate whether stratification in amnestic MCI could improve prediction accuracy. METHODS: We identified 80 and 79 patients with amnestic MCI from different cohorts, respectively. They underwent baseline magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scans...
April 12, 2016: Journal of Alzheimer's Disease: JAD
Amy L Proskovec, Elizabeth Heinrichs-Graham, Tony W Wilson
Working memory is central to the execution of many daily functions and is typically divided into three phases: encoding, maintenance, and retrieval. While working memory performance has been repeatedly shown to decline with age, less is known regarding the underlying neural processes. We examined age-related differences in the neural dynamics that serve working memory by recording high-density magnetoencephalography (MEG) in younger and older adults while they performed a modified, high-load Sternberg working memory task with letters as stimuli...
June 2016: Human Brain Mapping
Chihiro I Tajima, Satohiro Tajima, Kowa Koida, Hidehiko Komatsu, Kazuyuki Aihara, Hideyuki Suzuki
Categorical perception is a ubiquitous function in sensory information processing, and is reported to have important influences on the recognition of presented and/or memorized stimuli. However, such complex interactions among categorical perception and other aspects of sensory processing have not been explained well in a unified manner. Here, we propose a recurrent neural network model to process categorical information of stimuli, which approximately realizes a hierarchical Bayesian estimation on stimuli...
2016: Scientific Reports
Shao-Fang Wang, Maureen Ritchey, Laura A Libby, Charan Ranganath
Regional differences in large-scale connectivity have been proposed to underlie functional specialization along the anterior-posterior axis of the medial temporal lobe (MTL), including the hippocampus (HC) and the parahippocampal gyrus (PHG). However, it is unknown whether functional connectivity (FC) can be used reliably to parcellate the human MTL. The current study aimed to differentiate subregions of the HC and the PHG based on patterns of whole-brain intrinsic FC. FC maps were calculated for each slice along the longitudinal axis of the PHG and the HC...
October 2016: Neurobiology of Learning and Memory
Allen Ardestani, Wei Shen, Felix Darvas, Arthur W Toga, Joaquin M Fuster
Our perception of the world is represented in widespread, overlapping, and interactive neuronal networks of the cerebral cortex. A majority of physiological studies on the subject have focused on oscillatory synchrony as the binding mechanism for representation and transmission of neural information. Little is known, however, about the stability of that synchrony during prolonged cognitive operations that span more than just a few seconds. The present research, in primates, investigated the dynamic patterns of oscillatory synchrony by two complementary recording methods, surface field potentials (SFPs) and near-infrared spectroscopy (NIRS)...
March 2016: Journal of Cognitive Neuroscience
Johan Westö, Patrick J C May, Hannu Tiitinen
Robust representations of sounds with a complex spectrotemporal structure are thought to emerge in hierarchically organized auditory cortex, but the computational advantage of this hierarchy remains unknown. Here, we used computational models to study how such hierarchical structures affect temporal binding in neural networks. We equipped individual units in different types of feedforward networks with local memory mechanisms storing recent inputs and observed how this affected the ability of the networks to process stimuli context dependently...
February 2016: Neural Computation
Jordi Fonollosa, Emre Neftci, Mikhail Rabinovich
We often learn and recall long sequences in smaller segments, such as a phone number 858 534 22 30 memorized as four segments. Behavioral experiments suggest that humans and some animals employ this strategy of breaking down cognitive or behavioral sequences into chunks in a wide variety of tasks, but the dynamical principles of how this is achieved remains unknown. Here, we study the temporal dynamics of chunking for learning cognitive sequences in a chunking representation using a dynamical model of competing modes arranged to evoke hierarchical Winnerless Competition (WLC) dynamics...
November 2015: PLoS Computational Biology
Wladimir J Alonso, Maia A Rabaa, Ricardo Giglio, Mark A Miller, Cynthia Schuck-Paim
Existing modeling approaches are divided between a focus on the constitutive (micro) elements of systems or on higher (macro) organization levels. Micro-level models enable consideration of individual histories and interactions, but can be unstable and subject to cumulative errors. Macro-level models focus on average population properties, but may hide relevant heterogeneity at the micro-scale. We present a framework that integrates both approaches through the use of temporally structured matrices that can take large numbers of variables into account...
2015: PloS One
Rishidev Chaudhuri, Kenneth Knoblauch, Marie-Alice Gariel, Henry Kennedy, Xiao-Jing Wang
We developed a large-scale dynamical model of the macaque neocortex, which is based on recently acquired directed- and weighted-connectivity data from tract-tracing experiments, and which incorporates heterogeneity across areas. A hierarchy of timescales naturally emerges from this system: sensory areas show brief, transient responses to input (appropriate for sensory processing), whereas association areas integrate inputs over time and exhibit persistent activity (suitable for decision-making and working memory)...
October 21, 2015: Neuron
Bernhard P Staresina, Til Ole Bergmann, Mathilde Bonnefond, Roemer van der Meij, Ole Jensen, Lorena Deuker, Christian E Elger, Nikolai Axmacher, Juergen Fell
During systems-level consolidation, mnemonic representations initially reliant on the hippocampus are thought to migrate to neocortical sites for more permanent storage, with an eminent role of sleep for facilitating this information transfer. Mechanistically, consolidation processes have been hypothesized to rely on systematic interactions between the three cardinal neuronal oscillations characterizing non-rapid eye movement (NREM) sleep. Under global control of de- and hyperpolarizing slow oscillations (SOs), sleep spindles may cluster hippocampal ripples for a precisely timed transfer of local information to the neocortex...
November 2015: Nature Neuroscience
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