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hierarchical temporal memory

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https://www.readbyqxmd.com/read/28195521/a-computational-model-of-perceptual-and-mnemonic-deficits-in-medial-temporal-lobe-amnesia
#1
Patrick S Sadil, Rosemary A Cowell
Damage to the medial temporal lobe (MTL) has long been known to impair declarative memory, and recent evidence suggests that it also impairs visual perception. A theory termed the representational-hierarchical account explains such impairments by assuming that MTL stores conjunctive representations of items and events, and that individuals with MTL damage must rely upon representations of simple visual features in posterior visual cortex, which are inadequate to support memory and perception under certain circumstances...
February 14, 2017: Journal of Cognitive Neuroscience
https://www.readbyqxmd.com/read/28159686/frequency-specific-electrophysiologic-correlates-of-resting-state-fmri-networks
#2
Carl D Hacker, Abraham Z Snyder, Mrinal Pahwa, Maurizio Corbetta, Eric C Leuthardt
Resting state functional MRI (R-fMRI) studies have shown that slow (<0.1Hz), intrinsic fluctuations of the blood oxygen level dependent (BOLD) signal are temporally correlated within hierarchically organized functional systems known as resting state networks (RSNs) (Doucet et al., 2011). Most broadly, this hierarchy exhibits a dichotomy between two opposed systems (Fox et al., 2005). One system engages with the environment and includes the visual, auditory, and sensorimotor (SMN) networks as well as the dorsal attention network (DAN), which controls spatial attention...
January 31, 2017: NeuroImage
https://www.readbyqxmd.com/read/28088041/the-role-of-the-ifg-and-psts-in-syntactic-prediction-evidence-from-a-parametric-study-of-hierarchical-structure-in-fmri
#3
William Matchin, Christopher Hammerly, Ellen Lau
Sentences encode hierarchical structural relations among words. Several neuroimaging experiments aiming to localize combinatory operations responsible for creating this structure during sentence comprehension have contrasted short, simple phrases and sentences to unstructured controls. Some of these experiments have revealed activation in the left inferior frontal gyrus (IFG) and posterior superior temporal sulcus (pSTS), associating these regions with basic syntactic combination. However, the wide variability of these effects across studies raises questions about this interpretation...
March 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/27994564/the-temporal-order-of-word-presentation-modulates-the-amplitudes-of-p2-and-n400-during-recognition-of-causal-relations
#4
Xiuling Liang, Feng Xiao, Lijun Wu, Qingfei Chen, Yi Lei, Hong Li
The processing of causal relations has been constantly found to be asymmetrical once the roles of cause and effect are assigned to objects in interactions. We used a relationship recognition paradigm and recorded electroencephalographic (EEG) signals to explore the neural mechanism underlying the asymmetrical representations of causal relations in semantic memory. The results revealed that the verification of causal relations is faster if two words appear in "cause-effect" order (e.g., virus-epidemic) than if they appear in "effect-cause" order (e...
2016: Frontiers in Psychology
https://www.readbyqxmd.com/read/27940303/neural-representation-of-a-melodic-motif-effects-of-polyphonic-contexts
#5
Madeline Huberth, Takako Fujioka
In music, a melodic motif is often played repeatedly in different pitch ranges and at different times. Event-related potential (ERP) studies have shown that the mismatch negativity (MMN) reflects memory trace processing that encodes two separate melodic lines ("voices") with different motifs. Here we investigated whether a single motif presented in two voices is encoded as a single entity or two separate entities, and whether motifs overlapping in time impede or enhance encoding strength. Electroencephalogram (EEG) from 11 musically-trained participants was recorded while they passively listened to sequences of 5-note motifs where the 5th note either descended (standard) or ascended (deviant) relative to the previous note (20% deviant rate)...
February 2017: Brain and Cognition
https://www.readbyqxmd.com/read/27930903/brain-mechanisms-underlying-the-brief-maintenance-of-seen-and-unseen-sensory-information
#6
Jean-Rémi King, Niccolo Pescetelli, Stanislas Dehaene
Recent evidence of unconscious working memory challenges the notion that only visible stimuli can be actively maintained over time. In the present study, we investigated the neural dynamics underlying the maintenance of variably visible stimuli using magnetoencephalography. Subjects had to detect and mentally maintain the orientation of a masked grating. We show that the stimulus is fully encoded in early brain activity independently of visibility reports. However, the presence and orientation of the target are actively maintained throughout the brief retention period, even when the stimulus is reported as unseen...
December 7, 2016: Neuron
https://www.readbyqxmd.com/read/27891101/spatio-temporal-structure-path-characteristics-and-perceptual-grouping-in-immediate-serial-spatial-recall
#7
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
https://www.readbyqxmd.com/read/27713712/vowels-and-consonants-in-the-brain-evidence-from-magnetoencephalographic-studies-on-the-n1m-in-normal-hearing-listeners
#8
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
https://www.readbyqxmd.com/read/27639121/classifying-anatomical-subtypes-of-subjective-memory-impairment
#9
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...
December 2016: Neurobiology of Aging
https://www.readbyqxmd.com/read/27626963/continuous-online-sequence-learning-with-an-unsupervised-neural-network-model
#10
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
https://www.readbyqxmd.com/read/27618549/dynamic-organization-of-hierarchical-memories
#11
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
https://www.readbyqxmd.com/read/27592283/malignant-progression-in-parietal-dominant-atrophy-subtype-of-alzheimer-s-disease-occurs-independent-of-onset-age
#12
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
https://www.readbyqxmd.com/read/27498041/different-fdg-pet-metabolic-patterns-at-single-subject-level-in-the-behavioral-variant-of-fronto-temporal-dementia
#13
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
https://www.readbyqxmd.com/read/27418578/declarative-association-in-the-perirhinal-cortex
#14
REVIEW
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...
December 2016: Neuroscience Research
https://www.readbyqxmd.com/read/27377221/temporo-parietal-connectivity-uniquely-predicts-reading-change-from-childhood-to-adolescence
#15
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...
November 15, 2016: NeuroImage
https://www.readbyqxmd.com/read/27184459/the-organisation-of-spatial-and-temporal-relations-in-memory
#16
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...
April 2017: Memory
https://www.readbyqxmd.com/read/27079727/prediction-of-alzheimer-s-disease-in-amnestic-mild-cognitive-impairment-subtypes-stratification-based-on-imaging-biomarkers
#17
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
https://www.readbyqxmd.com/read/26991358/aging-modulates-the-oscillatory-dynamics-underlying-successful-working-memory-encoding-and-maintenance
#18
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
https://www.readbyqxmd.com/read/26935275/population-code-dynamics-in-categorical-perception
#19
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...
March 3, 2016: Scientific Reports
https://www.readbyqxmd.com/read/26805590/functional-connectivity-based-parcellation-of-the-human-medial-temporal-lobe
#20
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
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