scholarly journals Layer-dependent activity in human prefrontal cortex during working memory

2018 ◽  
Author(s):  
Emily S. Finn ◽  
Laurentius Huber ◽  
David C. Jangraw ◽  
Peter A. Bandettini
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Memory Task ◽  
Brain Regions ◽  
Cognitive Information Processing ◽  
Dependent Activity ◽  
Dorsolateral Prefrontal ◽  
Cognitive Information ◽  
Series Of Functions ◽  
Layer Specificity

Working memory involves a series of functions: encoding a stimulus, maintaining or manipulating its representation over a delay, and finally making a behavioral response. While working memory engages dorsolateral prefrontal cortex (dlPFC), few studies have investigated whether these subfunctions are localized to different cortical depths in this region, and none have done so in humans. Here, we use high-resolution functional MRI to interrogate the layer specificity of neural activity during different epochs of a working memory task in dlPFC. We detect activity timecourses that follow the hypothesized patterns: superficial layers are preferentially active during the delay period, while deeper layers are preferentially active during the response. Results demonstrate that layer-specific fMRI can be used in higher-order brain regions to non-invasively map cognitive information processing along cortical circuitry in humans.

scholarly journals Prefrontal and Parietal Attractor Networks Mediate Working Memory Judgments

2020 ◽  
Author(s):  
Sihai Li ◽  
Christos Constantinidis ◽  
Xue-Lian Qi
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Critical Role ◽  
Memory Task ◽  
Delayed Response ◽  
Persistent Activity ◽  
Neural Basis ◽  
Brain Areas ◽  
Dorsolateral Prefrontal

ABSTRACTThe dorsolateral prefrontal cortex plays a critical role in spatial working memory and its activity predicts behavioral responses in delayed response tasks. Here we addressed whether this predictive ability extends to categorical judgments based on information retained in working memory, and is present in other brain areas. We trained monkeys in a novel, Match-Stay, Nonmatch-Go task, which required them to observe two stimuli presented in sequence with an intervening delay period between them. If the two stimuli were different, the monkeys had to saccade to the location of the second stimulus; if they were the same, they held fixation. Neurophysiological recordings were performed in areas 8a and 46 of the dlPFC and 7a and lateral intraparietal cortex (LIP) of the PPC. We hypothesized that random drifts causing the peak activity of the network to move away from the first stimulus location and towards the location of the second stimulus would result in categorical errors. Indeed, for both areas, when the first stimulus appeared in a neuron’s preferred location, the neuron showed significantly higher firing rates in correct than in error trials. When the first stimulus appeared at a nonpreferred location and the second stimulus at a preferred, activity in error trials was higher than in correct. The results indicate that the activity of both dlPFC and PPC neurons is predictive of categorical judgments of information maintained in working memory, and the magnitude of neuronal firing rate deviations is revealing of the contents of working memory as it determines performance.SIGNIFICANCE STATEMENTThe neural basis of working memory and the areas mediating this function is a topic of controversy. Persistent activity in the prefrontal cortex has traditionally been thought to be the neural correlate of working memory, however recent studies have proposed alternative mechanisms and brain areas. Here we show that persistent activity in both the dorsolateral prefrontal cortex and posterior parietal cortex predicts behavior in a working memory task that requires a categorical judgement. Our results offer support to the idea that a network of neurons in both areas act as an attractor network that maintains information in working memory, which informs behavior.

scholarly journals Continuous theta-burst stimulation over the dorsolateral prefrontal cortex inhibits improvement on a working memory task

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Teodóra Vékony ◽  
Viola Luca Németh ◽  
Adrienn Holczer ◽  
Krisztián Kocsis ◽  
Zsigmond Tamás Kincses ◽  
...  
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Memory Task ◽  
Theta Burst Stimulation ◽  
Burst Stimulation ◽  
Dorsolateral Prefrontal ◽  
Theta Burst ◽  
Continuous Theta Burst Stimulation

A Large-scale Neurocomputational Model of Task-oriented Behavior Selection and Working Memory in Prefrontal Cortex

2006 ◽  
Vol 18 (2) ◽  
pp. 242-257 ◽  
Author(s):  
George L. Chadderdon ◽  
Olaf Sporns
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Large Scale ◽  
Memory Task ◽  
Brain Regions ◽  
Synaptic Activity ◽  
Dynamic State ◽  
Memory Representation ◽  
Behavioral Repertoire ◽  
Behavior Selection

The prefrontal cortex (PFC) is crucially involved in the executive component of working memory, representation of task state, and behavior selection. This article presents a large-scale computational model of the PFC and associated brain regions designed to investigate the mechanisms by which working memory and task state interact to select adaptive behaviors from a behavioral repertoire. The model consists of multiple brain regions containing neuronal populations with realistic physiological and anatomical properties, including extrastriate visual cortical regions, the inferotemporal cortex, the PFC, the striatum, and midbrain dopamine (DA) neurons. The onset of a delayed match-to-sample or delayed nonmatch-to-sample task triggers tonic DA release in the PFC causing a switch into a persistent, stimulus-insensitive dynamic state that promotes the maintenance of stimulus representations within prefrontal networks. Other modeled prefrontal and striatal units select cognitive acceptance or rejection behaviors according to which task is active and whether prefrontal working memory representations match the current stimulus. Working memory task performance and memory fields of prefrontal delay units are degraded by extreme elevation or depletion of tonic DA levels. Analyses of cellular and synaptic activity suggest that hyponormal DA levels result in increased prefrontal activation, whereas hypernormal DA levels lead to decreased activation. Our simulation results suggest a range of predictions for behavioral, single-cell, and neuroimaging response data under the proposed task set and under manipulations of DA concentration.

scholarly journals Neurons with inverted tuning during the delay periods of working memory tasks in the dorsal prefrontal and posterior parietal cortex

2012 ◽  
Vol 108 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Xin Zhou ◽  
Fumi Katsuki ◽  
Xue-Lian Qi ◽  
Christos Constantinidis
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Memory Task ◽  
Functional Difference ◽  
Initial Stimulus ◽  
Cortical Afferents ◽  
Dorsolateral Prefrontal ◽  
Posterior Parietal

The dorsolateral prefrontal and posterior parietal cortices are two interconnected brain areas that are coactivated in tasks involving functions such as spatial attention and working memory. The response properties of neurons in the two areas are in many respects indistinguishable, yet only prefrontal neurons are able to resist interference by distracting stimuli when subjects are required to remember an initial stimulus. Several mechanisms have been proposed that could account for this functional difference, including the existence of specialized interneuron types, specific to the prefrontal cortex. Although such neurons with inverted tuning during the delay period of a working memory task have been described in the prefrontal cortex, no comparative data exist from other cortical areas that would establish a unique prefrontal role. To test this hypothesis, we analyzed a large database of recordings obtained in the dorsolateral prefrontal and posterior parietal cortex of the same monkeys as they performed working memory tasks. We found that in the prefrontal cortex, neurons with inverted tuning were more numerous and manifested unique properties. Our results give credence to the idea that a division of labor exists between separate neuron types in the prefrontal cortex and that this represents a functional specialization that is not present in its cortical afferents.

scholarly journals High-Definition Transcranial Direct Current Stimulation Over the Right Lateral Prefrontal Cortex Increases Maximization Tendencies

2021 ◽  
Vol 15 ◽  
Author(s):  
Haixia Wang ◽  
Hanqi Zhang
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Memory Task ◽  
High Definition ◽  
Direct Current Stimulation ◽  
Dorsolateral Prefrontal ◽  
The Right ◽  
Motivational Changes

People seek the best in every aspect of life. However, little is known about the neurobiological mechanisms supporting this process of maximization. In this study, maximization tendencies were increased by using high-definition transcranial direct current stimulation (HD-tDCS) over the right dorsolateral prefrontal cortex (DLPFC). Participants (n = 64) received 2 mA anodal 4 × 1 HD-tDCS or sham stimulation over the right DLPFC in two sessions and subsequently completed an N-back working memory task and a maximization scale (MS). We observed that maximization tendency scores increased during anodal stimulation. Furthermore, the results indicate that this increase in maximization tendency was driven by motivational changes. On the MS, alternative search subscale scores were significantly increased, demonstrating an increase in motivation to evaluate more alternatives; however, the results did not indicate that the increase in maximization tendencies was due to working memory improvement. These results demonstrated that maximization tendencies can be strengthened through noninvasive interventions and that the right DLPFC has a causal relationship with maximization tendencies.

scholarly journals Prefrontal Cortex Modulation during Anticipation of Working Memory Demands as Revealed by Magnetoencephalography

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Mario Altamura ◽  
Terry E. Goldberg ◽  
Brita Elvevåg ◽  
Tom Holroyd ◽  
Frederick W. Carver ◽  
...  
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Brain Regions ◽  
Higher Order ◽  
Task Demands ◽  
Beta Band ◽  
Stimulus Response ◽  
Synthetic Aperture Magnetometry ◽  
Beta Power ◽  
Dorsolateral Prefrontal

During the anticipation of task demands frontal control is involved in the assembly of stimulus-response mappings based on current goals. It is not clear whether prefrontal modulations occur in higher-order cortical regions, likely reflecting cognitive anticipation processes. The goal of this paper was to investigate prefrontal modulation during anticipation of upcoming working memory demands as revealed by magnetoencephalography (MEG). Twenty healthy volunteers underwent MEG while they performed a variation of the Sternberg Working Memory (WM) task. Beta band (14–30 Hz) SAM (Synthetic Aperture Magnetometry) analysis was performed. During the preparatory periods there was an increase in beta power (event-related synchronization) in dorsolateral prefrontal cortex (DLPFC) bilaterally, left inferior prefrontal gyrus, left parietal, and temporal areas. Our results provide support for the hypothesis that, during preparatory states, the prefrontal cortex is important for biasing higher order brain regions that are going to be engaged in the upcoming task.

scholarly journals Monkey prefrontal neurons during Sternberg task performance: full contents of working memory or most recent item?

2017 ◽  
Vol 117 (6) ◽  
pp. 2269-2281 ◽  
Author(s):  
R. O. Konecky ◽  
M. A. Smith ◽  
C. R. Olson
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Firing Rate ◽  
Dorsolateral Prefrontal Cortex ◽  
Memory Task ◽  
Delay Period ◽  
Population Activity ◽  
Storage Mechanism ◽  
Dorsolateral Prefrontal ◽  
Recent Item

To explore the brain mechanisms underlying multi-item working memory, we monitored the activity of neurons in the dorsolateral prefrontal cortex while macaque monkeys performed spatial and chromatic versions of a Sternberg working-memory task. Each trial required holding three sequentially presented samples in working memory so as to identify a subsequent probe matching one of them. The monkeys were able to recall all three samples at levels well above chance, exhibiting modest load and recency effects. Prefrontal neurons signaled the identity of each sample during the delay period immediately following its presentation. However, as each new sample was presented, the representation of antecedent samples became weak and shifted to an anomalous code. A linear classifier operating on the basis of population activity during the final delay period was able to perform at approximately the level of the monkeys on trials requiring recall of the third sample but showed a falloff in performance on trials requiring recall of the first or second sample much steeper than observed in the monkeys. We conclude that delay-period activity in the prefrontal cortex robustly represented only the most recent item. The monkeys apparently based performance of this classic working-memory task on some storage mechanism in addition to the prefrontal delay-period firing rate. Possibilities include delay-period activity in areas outside the prefrontal cortex and changes within the prefrontal cortex not manifest at the level of the firing rate. NEW & NOTEWORTHY It has long been thought that items held in working memory are encoded by delay-period activity in the dorsolateral prefrontal cortex. Here we describe evidence contrary to that view. In monkeys performing a serial multi-item working memory task, dorsolateral prefrontal neurons encode almost exclusively the identity of the sample presented most recently. Information about earlier samples must be encoded outside the prefrontal cortex or represented within the prefrontal cortex in a cryptic code.

Schizophrenic subjects activate dorsolateral prefrontal cortex during a working memory task, as measured by fMRI

1999 ◽  
Vol 45 (9) ◽  
pp. 1128-1137 ◽  
Author(s):  
Dara S Manoach ◽  
Daniel Z Press ◽  
Venkatassen Thangaraj ◽  
Meghan M Searl ◽  
Donald C Goff ◽  
...  
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Memory Task ◽  
Dorsolateral Prefrontal
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