scholarly journals Distinct cortical systems reinstate the content and context of episodic memories

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
James E. Kragel ◽  
Youssef Ezzyat ◽  
Bradley C. Lega ◽  
Michael R. Sperling ◽  
Gregory A. Worrell ◽  
...  
Keyword(s):  
Functional Neuroimaging ◽  
Semantic Category ◽  
Semantic Content ◽  
Neural Systems ◽  
Temporal Context ◽  
Memory Recall ◽  
Temporal Networks ◽  
Episodic Memories ◽  
Types Of Information ◽  
Intracranial Recordings

AbstractEpisodic recall depends upon the reinstatement of cortical activity present during the formation of a memory. Evidence from functional neuroimaging and invasive recordings in humans suggest that reinstatement organizes our memories by time or content, yet the neural systems involved in reinstating these unique types of information remain unclear. Here, combining computational modeling and intracranial recordings from 69 epilepsy patients, we show that two cortical systems uniquely reinstate the semantic content and temporal context of previously studied items during free recall. Examining either the posterior medial or anterior temporal networks, we find that forward encoding models trained on the brain’s response to the temporal and semantic attributes of items can predict the serial position and semantic category of unseen items. During memory recall, these models uniquely link reinstatement of temporal context and semantic content to these posterior and anterior networks, respectively. These findings demonstrate how specialized cortical systems enable the human brain to target specific memories.

scholarly journals Distinct cortical systems reinstate the content and context of episodic memories

2020 ◽  
Author(s):  
James E. Kragel ◽  
Youssef Ezzyat ◽  
Bradley C. Lega ◽  
Michael R. Sperling ◽  
Gregory A. Worrell ◽  
...  
Keyword(s):  
Free Recall ◽  
Functional Connectivity ◽  
Human Brain ◽  
Semantic Content ◽  
Cortical Activity ◽  
Temporal Context ◽  
Cortical Networks ◽  
Semantic Organization ◽  
Episodic Memories

AbstractEpisodic recall depends upon the reinstatement of cortical activity present during the formation of a memory. We identified dissociable cortical networks via functional connectivity that uniquely reinstated semantic content and temporal context of previously studied stimuli during free recall. Network-specific reinstatement predicted the temporal and semantic organization of recall sequences, demonstrating how specialized cortical systems enable the human brain to target specific memories.

scholarly journals Ekstraksi Informasi Halaman Web Menggunakan Pendekatan Bootstrapping pada Ontology-Based Information Extraction

2015 ◽  
Vol 9 (2) ◽  
pp. 111 ◽  
Author(s):  
Erma Susanti ◽  
Khabib Mustofa
Keyword(s):  
Information Extraction ◽  
Language Processing ◽  
Semantic Content ◽  
Extraction Process ◽  
Web Pages ◽  
Structured Information ◽  
Improved Performance ◽  
Types Of Information ◽  
Unstructured Information

AbstrakEkstraksi  informasi  merupakan suatu bidang ilmu untuk pengolahan bahasa alami, dengan cara mengubah teks tidak terstruktur menjadi informasi dalam bentuk terstruktur. Berbagai jenis informasi di Internet ditransmisikan secara tidak terstruktur melalui website, menyebabkan munculnya kebutuhan akan suatu teknologi untuk menganalisa teks dan menemukan pengetahuan yang relevan dalam bentuk informasi terstruktur. Contoh informasi tidak terstruktur adalah informasi utama yang ada pada konten halaman web. Bermacam pendekatan untuk ekstraksi informasi telah dikembangkan oleh berbagai peneliti, baik menggunakan metode manual atau otomatis, namun masih perlu ditingkatkan kinerjanya terkait akurasi dan kecepatan ekstraksi. Pada penelitian ini diusulkan suatu penerapan pendekatan ekstraksi informasi dengan mengkombinasikan pendekatan bootstrapping dengan Ontology-based Information Extraction (OBIE). Pendekatan bootstrapping dengan menggunakan sedikit contoh data berlabel, digunakan untuk memimalkan keterlibatan manusia dalam proses ekstraksi informasi, sedangkan penggunakan panduan ontologi untuk mengekstraksi classes (kelas), properties dan instance digunakan untuk menyediakan konten semantik untuk web semantik. Pengkombinasian kedua pendekatan tersebut diharapkan dapat meningkatan kecepatan proses ekstraksi dan akurasi hasil ekstraksi. Studi kasus untuk penerapan sistem ekstraksi informasi menggunakan dataset “LonelyPlanet”. Kata kunci—Ekstraksi informasi, ontologi, bootstrapping, Ontology-Based Information Extraction, OBIE, kinerja Abstract Information extraction is a field study of natural language processing by converting unstructured text into structured information. Several types of information on the Internet is transmitted through unstructured information via websites, led to emergence of the need a technology to analyze text and found relevant knowledge into structured information. For example of unstructured information is existing main information on the content of web pages. Various approaches  for information extraction have been developed by many researchers, either using manual or automatic method, but still need to be improved performance related accuracy and speed of extraction. This research proposed an approach of information extraction that combines bootstrapping approach with Ontology-Based Information Extraction (OBIE). Bootstrapping approach using small seed of labelled data, is used to minimize human intervention on information extraction process, while the use of guide ontology for extracting classes, properties and instances, using for provide semantic content for semantic web. Combining both approaches expected to increase speed of extraction process and accuracy of extraction results. Case study to apply information extraction system using “LonelyPlanet” datasets. Keywords— Information extraction, ontology, bootstrapping, Ontology-Based Information Extraction, OBIE, performance

scholarly journals Neural systems supporting lexical search guided by letter and semantic category cues: A self-paced overt response fMRI study of verbal fluency

NeuroImage ◽  
2010 ◽  
Vol 49 (1) ◽  
pp. 1099-1107 ◽  
Author(s):  
Rasmus M. Birn ◽  
Lauren Kenworthy ◽  
Laura Case ◽  
Rachel Caravella ◽  
Tyler B. Jones ◽  
...  
Keyword(s):  
Verbal Fluency ◽  
Semantic Category ◽  
Neural Systems ◽  
Overt Response ◽  
Fmri Study

scholarly journals Human Empathy Through the Lens of Social Neuroscience

2006 ◽  
Vol 6 ◽  
pp. 1146-1163 ◽  
Author(s):  
Jean Decety ◽  
Claus Lamm
Keyword(s):  
Information Processing ◽  
Cognitive Neuroscience ◽  
Executive Control ◽  
Perspective Taking ◽  
Functional Neuroimaging ◽  
Social Neuroscience ◽  
Neural Mechanisms ◽  
The Self ◽  
Neural Systems

Empathy is the ability to experience and understand what others feel without confusion between oneself and others. Knowing what someone else is feeling plays a fundamental role in interpersonal interactions. In this paper, we articulate evidence from social psychology and cognitive neuroscience, and argue that empathy involves both emotion sharing (bottom-up information processing) and executive control to regulate and modulate this experience (top-down information processing), underpinned by specific and interacting neural systems. Furthermore, awareness of a distinction between the experiences of the self and others constitutes a crucial aspect of empathy. We discuss data from recent behavioral and functional neuroimaging studies with an emphasis on the perception of pain in others, and highlight the role of different neural mechanisms that underpin the experience of empathy, including emotion sharing, perspective taking, and emotion regulation.

scholarly journals Neural systems underlying affective disorders

2003 ◽  
Vol 9 (6) ◽  
pp. 446-455 ◽  
Author(s):  
Simon Surguladze ◽  
Paul Keedwell ◽  
Mary Phillips
Keyword(s):  
Affective Disorders ◽  
Mood Induction ◽  
Functional Neuroimaging ◽  
Bipolar Depression ◽  
Temporal Cortex ◽  
Anterior Cingulate ◽  
Neural Systems ◽  
Emotional Facial Expressions ◽  
Complex Picture ◽  
Lesion Studies

Three main approaches are used to explore the neural correlates of mood disorder: neuropsychological studies, neuroimaging studies and post-mortem investigations. Lesion studies implicate disturbances in the frontal lobe, basal ganglia, striatum and anterior temporal cortex. Early neurocognitive and neuropathological investigations led to a ‘hypofrontality’ hypothesis of unipolar and bipolar depression, but functional neuroimaging has revealed a more complex picture. Thus, increased metabolism may occur in the subgenual anterior cingulate gyrus in resting-state studies of depression and sad-mood induction. Antidepressants may reduce this activity. Amygdala hyperactivation also is associated with affective disorders. Task-related studies reveal abnormal biases in memory, the experience of pleasure and the perception of emotional facial expressions. There is still little clarity whether the abnormalities in brain activation represent state or trait characteristics of affective disorders.

scholarly journals Neural diffusivity and pre-emptive epileptic seizure intervention

2020 ◽  
Vol 16 (12) ◽  
pp. e1008448
Author(s):  
Erik D. Fagerholm ◽  
Chayanin Tangwiriyasakul ◽  
Karl J. Friston ◽  
Inês R. Violante ◽  
Steven Williams ◽  
...  
Keyword(s):  
Neural Activity ◽  
Epileptic Seizure ◽  
Functional Neuroimaging ◽  
Epileptic Seizures ◽  
State Equation ◽  
Neural Systems ◽  
Dynamical Regime ◽  
External Stimulation ◽  
Neuroimaging Data ◽  
Intuitive Method

The propagation of epileptic seizure activity in the brain is a widespread pathophysiology that, in principle, should yield to intervention techniques guided by mathematical models of neuronal ensemble dynamics. During a seizure, neural activity will deviate from its current dynamical regime to one in which there are significant signal fluctuations. In silico treatments of neural activity are an important tool for the understanding of how the healthy brain can maintain stability, as well as of how pathology can lead to seizures. The hope is that, contained within the mathematical foundations of such treatments, there lie potential strategies for mitigating instabilities, e.g. via external stimulation. Here, we demonstrate that the dynamic causal modelling neuronal state equation generalises to a Fokker-Planck formalism if one extends the framework to model the ways in which activity propagates along the structural connections of neural systems. Using the Jacobian of this generalised state equation, we show that an initially unstable system can be rendered stable via a reduction in diffusivity–i.e., by lowering the rate at which neuronal fluctuations disperse to neighbouring regions. We show, for neural systems prone to epileptic seizures, that such a reduction in diffusivity can be achieved via external stimulation. Specifically, we show that this stimulation should be applied in such a way as to temporarily mirror the activity profile of a pathological region in its functionally connected areas. This counter-intuitive method is intended to be used pre-emptively–i.e., in order to mitigate the effects of the seizure, or ideally even prevent it from occurring in the first place. We offer proof of principle using simulations based on functional neuroimaging data collected from patients with idiopathic generalised epilepsy, in which we successfully suppress pathological activity in a distinct sub-network prior to seizure onset. Our hope is that this technique can form the basis for future real-time monitoring and intervention devices that are capable of treating epilepsy in a non-invasive manner.

Proactive inhibition and semantic organization Relationship with verbal memory in patients with schizophrenia

1996 ◽  
Vol 2 (6) ◽  
pp. 486-493 ◽  
Author(s):  
David A. Kareken ◽  
Paul J. Moberg ◽  
Ruben C. Gur
Keyword(s):  
Verbal Memory ◽  
Semantic Processing ◽  
Verbal Learning ◽  
Semantic Category ◽  
Semantic Content ◽  
Proactive Inhibition ◽  
California Verbal Learning Test ◽  
Retroactive Inhibition ◽  
Intrusion Errors ◽  
Learning Test

AbstractCompared to other cognitive functions in schizophrenia, evidence suggests that verbal memory is particularly impaired. This study used the California Verbal Learning Test (CVLT) to examine proactive inhibition (PI) and semantic processing in verbal memory in 29 patients with schizophrenia and 29 healthy controls. Patients showed significantly less PI, but also did not organize (cluster) their recall according to semantic category. Controls and patients demonstrated small retroactive inhibition (RI) effects regardless of semantic content. Although both groups made similar types and numbers of free recall intrusion errors, patients committed more phonemic and nonshared recognition errors. Results suggest that reduced semantic processing prevented build of PI, and contributes to defective memory in schizophrenia. The anatomic-physiologic abnormalities that underlie these findings may be particularly pronounced in prefrontal and temporal-parietal cortical areas. (JINS, 1996, 2, 486–493.)

Direct Comparison of Neural Systems Mediating Conscious and Unconscious Skill Learning

2002 ◽  
Vol 88 (3) ◽  
pp. 1451-1460 ◽  
Author(s):  
Daniel B. Willingham ◽  
Joanna Salidis ◽  
John D.E. Gabrieli
Keyword(s):  
Sequence Learning ◽  
Functional Neuroimaging ◽  
Brain Regions ◽  
Procedural Learning ◽  
Skill Learning ◽  
Adaptive Plasticity ◽  
Neural Systems ◽  
Motor Sequence ◽  
Learning Without Awareness ◽  
The Brain

Procedural learning, such as perceptual-motor sequence learning, has been suggested to be an obligatory consequence of practiced performance and to reflect adaptive plasticity in the neural systems mediating performance. Prior neuroimaging studies, however, have found that sequence learning accompanied with awareness (declarative learning) of the sequence activates entirely different brain regions than learning without awareness of the sequence (procedural learning). Functional neuroimaging was used to assess whether declarative sequence learning prevents procedural learning in the brain. Awareness of the sequence was controlled by changing the color of the stimuli to match or differ from the color used for random sequences. This allowed direct comparison of brain activation associated with procedural and declarative memory for an identical sequence. Activation occurred in a common neural network whether initial learning had occurred with or without awareness of the sequence, and whether subjects were aware or not aware of the sequence during performance. There was widespread additional activation associated with awareness of the sequence. This supports the view that some types of unconscious procedural learning occurs in the brain whether or not it is accompanied by conscious declarative knowledge.

scholarly journals Semantic Feature Analysis: Further Examination of Outcomes

2015 ◽  
Vol 24 (4) ◽  
Author(s):  
Catharine DeLong ◽  
Christina Nessler ◽  
Sandra Wright ◽  
Julie Wambaugh
Keyword(s):  
Semantic Information ◽  
Semantic Category ◽  
Semantic Content ◽  
Category Membership ◽  
Semantic Feature ◽  
Word Retrieval ◽  
Multiple Baseline ◽  
Feature Analysis ◽  
Semantic Feature Analysis ◽  
Naming Performance

Purpose The purpose of this investigation was to systematically examine outcomes associated with Semantic feature analysis, which is an established treatment for word-retrieval deficits in aphasia. Attributes of the experimental design and stimuli were manipulated to evaluate generalized naming of semantically related and unrelated items. In addition, the study was designed to examine changes in production of semantic information. Method Semantic feature analysis was applied in the context of multiple-baseline designs with 5 persons with chronic aphasia. Experimental items were controlled for semantic category membership, number of naming attempts, and provision of item names. Acquisition, generalization, and maintenance effects were measured in probes of naming performance. Production of semantic information was also measured in response to experimental items and in discourse tasks. Results Treatment was associated with systematic increases in naming of trained items for 4 of the 5 participants. Positive generalization to untrained exemplars of trained categories was found for repeatedly exposed items but not for limited-exposure items. Slight increases in production of semantic content were observed. Conclusion Repeated attempts to name untreated items appeared to play a role in generalization. Provision of the names of untrained items may have enhanced generalized responding for 2 participants.

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