scholarly journals An Emergent Neural Coactivity Code for Dynamic Memory

2019 ◽  
Author(s):  
Mohamady El-Gaby ◽  
Hayley M Reeve ◽  
Vítor Lopes-dos-Santos ◽  
Natalia Campo-Urriza ◽  
Pavel V Perestenko ◽  
...  
Keyword(s):  
Cognitive Processes ◽  
Memory Performance ◽  
Dynamic Environments ◽  
Emergent Property ◽  
Cognitive Variables ◽  
Spike Discharge ◽  
Dynamic Memory ◽  
Impaired Memory ◽  
Neural Ensembles ◽  
Hippocampal Ca1

Coincidental spike discharge amongst distributed groups of neurons is thought to provide an efficient mechanism for encoding percepts, actions and cognitive processes1–3. Short timescale coactivity can indeed bind neurons with similar tuning, giving rise to robust representations congruent with those of the participating neurons4–6. Alternatively, coactivity may also play a role in information processing through encoding variables not represented by individual neurons. While this type of emergent coactivity-based coding has been described for physically well-defined variables, including percepts and actions7–10, its role in encoding abstract cognitive variables remains unknown. Coactivity-based representation could provide a flexible code in dynamic environments, where animals must regularly learn short-lived behavioural contingencies. Here, we tested this possibility by training mice to discriminate two new behavioural contingencies every day, while monitoring and manipulating neural ensembles in the hippocampal CA1. We found that, while the spiking of neurons within their place fields is organised into congruent coactivity patterns representing discrete locations during unsupervised exploration of the learning enclosure, additional neurons synchronised their activity into spatially-untuned patterns that discriminated opposing learning contingencies. This contingency discrimination was an emergent property of millisecond timescale coactivity rather than the tuning of individual neurons, and predicted trial-by-trial memory performance. Moreover, optogenetic suppression of plastic inputs from the upstream left CA3 region during learning selectively impaired the computation of contingency-discriminating, but not space-representing CA1 coactivity patterns. This manipulation, but not silencing the more stable right CA3 inputs, impaired memory of the contingency discrimination. Thus, the computation of an emergent, coactivity-based discrimination code necessitates plastic synapses and supports dynamic, two-contingency memory.

Inefficient Encoding as an Explanation for Age-Related Deficits in Recollection-Based Processing

2014 ◽  
Vol 28 (3) ◽  
pp. 148-161 ◽  
Author(s):  
David Friedman ◽  
Ray Johnson
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Cognitive Processes ◽  
Brain Activity ◽  
Memory Performance ◽  
Brain Regions ◽  
Semantic Retrieval ◽  
Age Related ◽  
The Face ◽  
Episodic Memories

A cardinal feature of aging is a decline in episodic memory (EM). Nevertheless, there is evidence that some older adults may be able to “compensate” for failures in recollection-based processing by recruiting brain regions and cognitive processes not normally recruited by the young. We review the evidence suggesting that age-related declines in EM performance and recollection-related brain activity (left-parietal EM effect; LPEM) are due to altered processing at encoding. We describe results from our laboratory on differences in encoding- and retrieval-related activity between young and older adults. We then show that, relative to the young, in older adults brain activity at encoding is reduced over a brain region believed to be crucial for successful semantic elaboration in a 400–1,400-ms interval (left inferior prefrontal cortex, LIPFC; Johnson, Nessler, & Friedman, 2013 ; Nessler, Friedman, Johnson, & Bersick, 2007 ; Nessler, Johnson, Bersick, & Friedman, 2006 ). This reduced brain activity is associated with diminished subsequent recognition-memory performance and the LPEM at retrieval. We provide evidence for this premise by demonstrating that disrupting encoding-related processes during this 400–1,400-ms interval in young adults affords causal support for the hypothesis that the reduction over LIPFC during encoding produces the hallmarks of an age-related EM deficit: normal semantic retrieval at encoding, reduced subsequent episodic recognition accuracy, free recall, and the LPEM. Finally, we show that the reduced LPEM in young adults is associated with “additional” brain activity over similar brain areas as those activated when older adults show deficient retrieval. Hence, rather than supporting the compensation hypothesis, these data are more consistent with the scaffolding hypothesis, in which the recruitment of additional cognitive processes is an adaptive response across the life span in the face of momentary increases in task demand due to poorly-encoded episodic memories.

scholarly journals Checking Behaviours, Prospective Memory and Executive Functions

2015 ◽  
Vol 32 (2) ◽  
pp. 74-92 ◽  
Author(s):  
Lorna Elise Palmer ◽  
Kevin Durkin ◽  
Sinéad M. Rhodes
Keyword(s):  
Executive Function ◽  
Executive Functions ◽  
Prospective Memory ◽  
Cognitive Processes ◽  
Memory Performance ◽  
State University ◽  
Washington State University ◽  
Symptom Profile ◽  
The Relationship ◽  
Memory Questionnaire

Explanations implicating memory in the causes and severity of checking symptoms have focused primarily on retrospective memory, and relatively little attention has been paid to prospective memory. Limited research has examined the relationship between prospective memory and executive functions. We assessed whether impairments in prospective memory and executive function predict checking symptoms in a sample of 106 adults. Checking symptoms were assessed using the Padua Inventory Washington State University Revision (PI-WSUR). All participants completed the prospective memory questionnaire (PMQ) and four computerised executive function tasks from the CANTAB, measuring inhibition, planning, attention set-shifting and working memory. Prospective memory and inhibition predicted checking symptom severity. Importantly, there were no correlations between internally cued prospective memory and inhibition or between prospective memory aiding strategies and inhibition. These variables appear to have an independent role in checking. The current findings highlight prospective memory and inhibition as key contributors to the checking symptom profile and provide the first evidence that these cognitive processes may independently contribute to checking symptoms. These findings have implications for a model in which memory performance is thought to be secondary to impairments in executive functions.

scholarly journals Nearly Extensive Sequential Memory Lifetime Achieved by Coupled Nonlinear Neurons

2012 ◽  
Vol 24 (10) ◽  
pp. 2678-2699 ◽  
Author(s):  
Taro Toyoizumi
Keyword(s):  
Cognitive Processes ◽  
Neural Activity ◽  
Short Term Memory ◽  
Memory Performance ◽  
Linear Part ◽  
Network Size ◽  
Short Term ◽  
Time Step ◽  
Sequential Memory ◽  
The Brain

Many cognitive processes rely on the ability of the brain to hold sequences of events in short-term memory. Recent studies have revealed that such memory can be read out from the transient dynamics of a network of neurons. However, the memory performance of such a network in buffering past information has been rigorously estimated only in networks of linear neurons. When signal gain is kept low, so that neurons operate primarily in the linear part of their response nonlinearity, the memory lifetime is bounded by the square root of the network size. In this work, I demonstrate that it is possible to achieve a memory lifetime almost proportional to the network size, “an extensive memory lifetime,” when the nonlinearity of neurons is appropriately used. The analysis of neural activity revealed that nonlinear dynamics prevented the accumulation of noise by partially removing noise in each time step. With this error-correcting mechanism, I demonstrate that a memory lifetime of order [Formula: see text] can be achieved.

Amnesic syndrome in schizophrenia

1990 ◽  
Vol 20 (4) ◽  
pp. 967-972 ◽  
Author(s):  
P. J. McKenna ◽  
D. Tamlyn ◽  
C. E. Lund ◽  
A. M. Mortimer ◽  
S. Hammond ◽  
...  
Keyword(s):  
Clinical Picture ◽  
Memory Impairment ◽  
Memory Performance ◽  
Alzheimer Type ◽  
Intellectual Impairment ◽  
Impaired Memory ◽  
Alzheimer Type Dementia ◽  
Amnesic Syndrome ◽  
Form Part ◽  
Poor Memory

SynopsisMemory impairment is not usually considered to form part of the clinical picture of schizophrenia, except perhaps in severely deteriorated patients. In a survey of 60 patients encompassing all grades of severity and chronicity poor memory performance was found to be common, sometimes substantial, and disproportionately pronounced compared to the degree of general intellectual impairment. Although associated with severity and chronicity of illness, impaired memory was by no means confined to old, institutionalized, or markedly deteriorated patients. The pattern of deficit appeared to resemble that of the classic amnesic syndrome rather than that seen in Alzheimer-type dementia.

scholarly journals Hippocampal CA1 apical neuropil atrophy and memory performance in Alzheimer's disease

NeuroImage ◽  
2012 ◽  
Vol 63 (1) ◽  
pp. 194-202 ◽  
Author(s):  
Geoffrey A. Kerchner ◽  
Gayle K. Deutsch ◽  
Michael Zeineh ◽  
Robert F. Dougherty ◽  
Manojkumar Saranathan ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Memory Performance ◽  
Hippocampal Ca1

scholarly journals Different impact of task switching and response-category conflict on subsequent memory

2019 ◽  
Author(s):  
Michèle C. Muhmenthaler ◽  
Beat Meier
Keyword(s):  
Cognitive Control ◽  
Task Switching ◽  
Perceptual Load ◽  
Recall Performance ◽  
Memory Performance ◽  
Response Category ◽  
Stimulus Category ◽  
Impaired Memory ◽  
Different Types ◽  
The Impact

AbstractThe impact of cognitive control demands on long-term memory is mixed, with some conflicts leading to better, others leading to worse subsequent memory. The current study was designed to investigate how different types of cognitive control demands modulate the effects on memory. At study, participants had to switch between two classification tasks and later, free recall performance was assessed. The stimuli consisted of two interleaved words, one word had to be categorized and the other word had to be ignored. In four experiments, the congruency between target and ignored words was manipulated by changing the distractor category. This allowed us to investigate the impact of different types of conflict (i.e., task switching, perceptual load, response-category conflict, stimulus-category conflict). The results revealed that task switching impaired memory in all experiments. In Experiment 1, higher perceptual load also impaired memory. Experiments 2–4 showed that the co-activation of two words which required different responses (i.e., response-category conflict) enhanced memory performance but only when the conflict stimuli were presented in pure blocks. Overall, memory performance seems to depend on attentional policies. Withdrawing attention from target encoding results in lower memory performance. In contrast, focusing attention on the target results in enhanced memory performance.

scholarly journals The Effects of the Courtroom Context on Children's Memory and Anxiety

2003 ◽  
Vol 31 (1) ◽  
pp. 67-98 ◽  
Author(s):  
Rebecca Nathanson ◽  
Karen J. Saywitz
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Stress Response ◽  
Memory Performance ◽  
Law School ◽  
Child Witnesses ◽  
Impaired Memory ◽  
Induced Stress ◽  
Intervention Efficacy ◽  
Children's Memory

Modifications of the courtroom environment have been proposed to enhance the ability of child witnesses to offer complete and accurate testimony and reduce system-induced stress. However, these interventions have often been conceived without the benefit of empirical data demonstrating intervention efficacy. The present study examines the effects of the courtroom context on children's memory and anxiety. Eighty-one eight- to ten-year-olds participated in a staged event involving bodily touch, and two weeks later their memory for the event was tested. Half of the children were questioned in a mock courtroom in a university law school, and half were questioned in a small, private room adjacent to the courtroom. Children's heart rate was monitored throughout questioning. Results indicated that children questioned in the courtroom showed impaired memory performance and greater heart rate variability, indicative of a stress response, when compared with children interviewed in the small, private room.

Executive Impairment Is Associated with Impaired Memory Performance in Working-Aged Stroke Patients

2016 ◽  
Vol 22 (5) ◽  
pp. 551-560 ◽  
Author(s):  
Katri E.A. Turunen ◽  
Siiri P.K. Laari ◽  
Tatu V. Kauranen ◽  
Satu Mustanoja ◽  
Turgut Tatlisumak ◽  
...  
Keyword(s):  
Memory Performance ◽  
Executive Dysfunction ◽  
General Intelligence ◽  
Stroke Patients ◽  
Delayed Recall ◽  
Geometric Figures ◽  
Impaired Memory ◽  
Immediate Recall ◽  
List Learning ◽  
Executive Impairment

AbstractObjectives: Executive dysfunction is associated with impaired memory performance, but controversies remain about which aspects of memory are involved and how general intelligence influences these connections. We aimed to clarify these connections in stroke patients by comparing various memory measures in patients with and without executive impairment. Methods: Our consecutive cohort included patients with a first-ever ischemic stroke. Neuropsychological assessments were completed 6 months and 2 years after stroke. We classified patients as executively impaired, when at least two of five executive measures were defective at 6 months. At both 6 months and 2 years, we compared list learning of unrelated words, story recall, and recall of geometric figures in patients with and without executive impairment, while controlling for general intelligence. Results: Patients with executive impairment (n=66; 37%) performed worse in list learning (p=.001; partial η2=.058) and immediate recall of a logical passage (p=.010; partial η2=.037) 6 months after stroke compared to executively intact patients (n=113). At the end of the 2-year follow-up period, the patients who were executively impaired at 6 months (n=53; 37%) still performed worse than executively intact patients (n=92) in list learning (p<.001; partial η2=.096), and additionally in delayed recall of the list (p=.006; partial η2=.052) and immediate recall of geometric figures (p=.007; partial η2=.050). Conclusions: In our working-aged stroke patients, executive impairment was common. Executive impairment was associated with memory tasks that provided less inherent structure and required the use of active memory strategies. Clinicians should remember this role of executive dysfunction when interpreting memory performance. (JINS, 2016, 22, 1–10)

scholarly journals Intertextuality as cognitive modelling

2016 ◽  
Vol 9 (2) ◽  
pp. 244-267
Author(s):  
Tatyana Karpenko-Seccombe
Keyword(s):  
Cognitive Processing ◽  
Cognitive Processes ◽  
Knowledge Structures ◽  
Cognitive Modelling ◽  
Cognitive Perspective ◽  
Dynamic Memory ◽  
Cognitive Research ◽  
Analogical Mapping

The aim of this paper is to demonstrate a way in which the concept of cognitive modelling can be applied to studies of intertextuality. The paper suggests a fresh way of looking at intertextuality – from the perspective of the cognitive processes involved in decoding intertextual references, namely, analogical mapping across different domains. Our knowledge of cognitive processes is largely based on the study of cognitive processing of texts, but texts with intertextual references have until now been a less studied area of cognitive research. I define three different ways in which texts relate to each other: hard modelling, soft modelling and loose association. From a cognitive perspective, I suggest that mental processing of these texts involves different knowledge structures which I describe using Schank’s (1982, 1986, 1999) theory of dynamic memory.

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