scholarly journals Conjunctive representation of what and when in monkey hippocampus and lateral prefrontal cortex during an associative memory task

2019 ◽  
Author(s):  
Nathanael A. Cruzado ◽  
Zoran Tiganj ◽  
Scott L. Brincat ◽  
Earl K. Miller ◽  
Marc W. Howard
Keyword(s):  
Prefrontal Cortex ◽  
Associative Memory ◽  
Memory Task ◽  
Neural Recording ◽  
Temporal Coding ◽  
Adaptive Memory ◽  
Lateral Prefrontal Cortex ◽  
The Past ◽  
Large Numbers

AbstractAdaptive memory requires the organism to form associations that bridge between events separated in time. Many studies show interactions between hippocampus (HPC) and prefrontal cortex (PFC) during formation of such associations. We analyze neural recording from monkey HPC and PFC during a memory task that requires the monkey to associate stimuli separated by about a second in time. After the first stimulus was presented, large numbers of units in both HPC and PFC fired in sequence. Many units fired only when a particular stimulus was presented at a particular time in the past. These results indicate that both HPC and PFC maintain a temporal record of events that could be used to form associations across time. This temporal record of the past is a key component of the temporal coding hypothesis, a hypothesis in psychology that memory not only encodes what happened, but when it happened.

scholarly journals Conjunctive representation of what and when in monkey hippocampus and lateral prefrontal cortex during an associative memory task

Hippocampus ◽  
2020 ◽  
Vol 30 (12) ◽  
pp. 1332-1346 ◽  
Author(s):  
Nathanael A. Cruzado ◽  
Zoran Tiganj ◽  
Scott L. Brincat ◽  
Earl K. Miller ◽  
Marc W. Howard
Keyword(s):  
Prefrontal Cortex ◽  
Associative Memory ◽  
Memory Task ◽  
Lateral Prefrontal Cortex

scholarly journals Phase of Firing Coding of Learning Variables across Prefrontal Cortex, Anterior Cingulate Cortex and Striatum during Feature Learning

2019 ◽  
Author(s):  
Benjamin Voloh ◽  
Mariann Oemisch ◽  
Thilo Womelsdorf
Keyword(s):  
Prefrontal Cortex ◽  
Anterior Cingulate Cortex ◽  
Long Range ◽  
Cingulate Cortex ◽  
Temporal Coding ◽  
Anterior Cingulate ◽  
Prediction Errors ◽  
Lateral Prefrontal Cortex ◽  
Firing Rates ◽  
Reward Prediction

AbstractThe prefrontal cortex and striatum form a recurrent network whose spiking activity encodes multiple types of learning-relevant information. This spike-encoded information is evident in average firing rates, but finer temporal coding might allow multiplexing and enhanced readout across the connected the network. We tested this hypothesis in the fronto-striatal network of nonhuman primates during reversal learning of feature values. We found that neurons encoding current choice outcomes, outcome prediction errors, and outcome history in their firing rates also carried significant information in their phase-of-firing at a 10-25 Hz beta frequency at which they synchronized across lateral prefrontal cortex, anterior cingulate cortex and striatum. The phase-of-firing code exceeded information that could be obtained from firing rates alone, was strong for inter-areal connections, and multiplexed information at three different phases of the beta cycle that were offset from the preferred spiking phase of neurons. Taken together, these findings document the multiplexing of three different types of information in the phase-of-firing at an interareally shared beta oscillation frequency during goal-directed behavior.HighlightsLateral prefrontal cortex, anterior cingulate cortex and striatum show phase-of-firing encoding for outcome, outcome history and reward prediction errors.Neurons with phase-of-firing code synchronize long-range at 10-25 Hz.Spike phases encoding reward prediction errors deviate from preferred synchronization phases.Anterior cingulate cortex neurons show strongest long-range effects.

scholarly journals Ketamine disrupts naturalistic coding of working memory in primate lateral prefrontal cortex networks

2021 ◽  
Author(s):  
Megan Roussy ◽  
Rogelio Luna ◽  
Lyndon Duong ◽  
Benjamin Corrigan ◽  
Roberto A. Gulli ◽  
...  
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Spatial Working Memory ◽  
Memory Task ◽  
Memory Deficits ◽  
Lateral Prefrontal Cortex ◽  
Neuronal Populations ◽  
Neuronal Types ◽  
Fast Spiking ◽  
Selective Working

AbstractKetamine is a dissociative anesthetic drug, which has more recently emerged as a rapid-acting antidepressant. When acutely administered at subanesthetic doses, ketamine causes cognitive deficits like those observed in patients with schizophrenia, including impaired working memory. Although these effects have been linked to ketamine’s action as an N-methyl-D-aspartate receptor antagonist, it is unclear how synaptic alterations translate into changes in brain microcircuit function that ultimately influence cognition. Here, we administered ketamine to rhesus monkeys during a spatial working memory task set in a naturalistic virtual environment. Ketamine induced transient working memory deficits while sparing perceptual and motor skills. Working memory deficits were accompanied by decreased responses of fast spiking inhibitory interneurons and increased responses of broad spiking excitatory neurons in the lateral prefrontal cortex. This translated into a decrease in neuronal tuning and information encoded by neuronal populations about remembered locations. Our results demonstrate that ketamine differentially affects neuronal types in the neocortex; thus, it perturbs the excitation inhibition balance within prefrontal microcircuits and ultimately leads to selective working memory deficits.

scholarly journals Phase of firing coding of learning variables across the fronto-striatal network during feature-based learning

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Benjamin Voloh ◽  
Mariann Oemisch ◽  
Thilo Womelsdorf
Keyword(s):  
Prefrontal Cortex ◽  
Anterior Cingulate Cortex ◽  
Information Gain ◽  
Cingulate Cortex ◽  
Temporal Coding ◽  
Anterior Cingulate ◽  
Prediction Errors ◽  
Significant Information ◽  
Lateral Prefrontal Cortex ◽  
Firing Rates

Abstract The prefrontal cortex and striatum form a recurrent network whose spiking activity encodes multiple types of learning-relevant information. This spike-encoded information is evident in average firing rates, but finer temporal coding might allow multiplexing and enhanced readout across the connected network. We tested this hypothesis in the fronto-striatal network of nonhuman primates during reversal learning of feature values. We found that populations of neurons encoding choice outcomes, outcome prediction errors, and outcome history in their firing rates also carry significant information in their phase-of-firing at a 10–25 Hz band-limited beta frequency at which they synchronize across lateral prefrontal cortex, anterior cingulate cortex and anterior striatum when outcomes were processed. The phase-of-firing code exceeds information that can be obtained from firing rates alone and is evident for inter-areal connections between anterior cingulate cortex, lateral prefrontal cortex and anterior striatum. For the majority of connections, the phase-of-firing information gain is maximal at phases of the beta cycle that were offset from the preferred spiking phase of neurons. Taken together, these findings document enhanced information of three important learning variables at specific phases of firing in the beta cycle at an inter-areally shared beta oscillation frequency during goal-directed behavior.

Battlefields from Event to Heritage

2020 ◽  
Author(s):  
John Carman ◽  
Patricia Carman
Keyword(s):  
Twentieth Century ◽  
Security Studies ◽  
New Developments ◽  
Critical Security Studies ◽  
The Past ◽  
New Approaches ◽  
Large Numbers ◽  
The World ◽  
War And Conflict ◽  
Modern War

What is—or makes a place—a ‘historic battlefield’? From one perspective the answer is a simple one—it is a place where large numbers of people came together in an organized manner to fight one another at some point in the past. But from another perspective it is far more difficult to identify. Quite why any such location is a place of battle—rather than any other kind of event—and why it is especially historic is more difficult to identify. This book sets out an answer to the question of what a historic battlefield is in the modern imagination, drawing upon examples from prehistory to the twentieth century. Considering battlefields through a series of different lenses, treating battles as events in the past and battlefields as places in the present, the book exposes the complexity of the concept of historic battlefield and how it forms part of a Western understanding of the world. Taking its lead from new developments in battlefield study—especially archaeological approaches—the book establishes a link to and a means by which these new approaches can contribute to more radical thinking about war and conflict, especially to Critical Military and Critical Security Studies. The book goes beyond the study of battles as separate and unique events to consider what they mean to us and why we need them to have particular characteristics. It will be of interest to archaeologists, historians, and students of modern war in all its forms.

Public Policy Administration

1985 ◽  
Vol 47 ◽  
pp. 1-16
Author(s):  
Richard A. Brumback
Keyword(s):  
Rhode Island ◽  
General Level ◽  
American Government ◽  
Introductory Course ◽  
The Past ◽  
Business Colleges ◽  
Business College ◽  
Large Numbers ◽  
The Subject ◽  
One Year

The teaching of an introductory course in American Government can be a difficult and frustrating endeavor under even the best of circumstances. Given the general level of cynicism and/or lack of interest by large numbers of Americans regarding politics and politicians, the task of generating student enthusiasm, or even mild interest, toward the subject matter can indeed be an arduous one. When the teaching of such a course takes place in a business college, and when the student audience is “captive” to a college requirement that all students must take the course, the task can be rendered considerably more formidable.For the past six years I have been teaching such courses at business colleges — one year at Bryant College in Rhode Island, and the following five years at Bentley College in Massachusetts.

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