scholarly journals Anodal Transcranial Direct Current Stimulation Induces High Gamma-Band Activity in the Left Dorsolateral Prefrontal Cortex During a Working Memory Task: A Double-Blind, Randomized, Crossover Study

2019 ◽  
Vol 13 ◽  
Author(s):  
Takashi Ikeda ◽  
Tetsuya Takahashi ◽  
Hirotoshi Hiraishi ◽  
Daisuke N. Saito ◽  
Mitsuru Kikuchi
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Memory Task ◽  
Double Blind ◽  
Dorsolateral Prefrontal ◽  
High Gamma ◽  
Gamma Band Activity ◽  
Randomized Crossover Study ◽  
Band Activity

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 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

scholarly journals fMRI abnormalities in dorsolateral prefrontal cortex during a working memory task in manic, euthymic and depressed bipolar subjects

2010 ◽  
Vol 182 (1) ◽  
pp. 22-29 ◽  
Author(s):  
Jennifer Townsend ◽  
Susan Y. Bookheimer ◽  
Lara C. Foland–Ross ◽  
Catherine A. Sugar ◽  
Lori L. Altshuler
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Memory Task ◽  
Dorsolateral Prefrontal

Task-relevant Output Signals are Sent from Monkey Dorsolateral Prefrontal Cortex to the Superior Colliculus during a Visuospatial Working Memory Task

2009 ◽  
Vol 21 (5) ◽  
pp. 1023-1038 ◽  
Author(s):  
Kevin Johnston ◽  
Stefan Everling
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Superior Colliculus ◽  
Dorsolateral Prefrontal Cortex ◽  
Spatial Working Memory ◽  
Memory Task ◽  
Projection Neurons ◽  
Visuospatial Working Memory ◽  
Cortical Function ◽  
Dorsolateral Prefrontal

Visuospatial working memory is one of the most extensively investigated functions of the dorsolateral prefrontal cortex (DLPFC). Theories of prefrontal cortical function have suggested that this area exerts cognitive control by modulating the activity of structures to which it is connected. Here, we used the oculomotor system as a model in which to characterize the output signals sent from the DLPFC to a target structure during a classical spatial working memory task. We recorded the activity of identified DLPFC–superior colliculus (SC) projection neurons while monkeys performed a memory-guided saccade task in which they were required to generate saccades toward remembered stimulus locations. DLPFC neurons sent signals related to all aspects of the task to the SC, some of which were spatially tuned. These data provide the first direct evidence that the DLPFC sends task-relevant information to the SC during a spatial working memory task, and further support a role for the DLPFC in the direct modulation of other brain areas.

scholarly journals Does excitatory fronto-extracerebral tDCS lead to improved working memory performance?

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 219 ◽  
Author(s):  
Níall Lally ◽  
Camilla L. Nord ◽  
Vincent Walsh ◽  
Jonathan P. Roiser
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Memory Performance ◽  
Reference Electrode ◽  
Double Blind ◽  
Non Invasive ◽  
Stimulation Parameters ◽  
Dorsolateral Prefrontal ◽  
Better Than

Evidence suggests that excitatory transcranial direct current stimulation (tDCS) may improve performance on a wide variety of cognitive tasks. Due to the non-invasive and inexpensive nature of the method, harnessing its potential could be particularly useful for the treatment of neuropsychiatric illnesses involving cognitive dysfunction. However, questions remain regarding the efficacious stimulation parameters. Here, using a double-blind between-subjects design, we explored whether 1 mA excitatory (anodal) left dorsolateral prefrontal cortex stimulation with a contralateral extracerebral reference electrode, leads to enhanced working memory performance across two days, relative to sham stimulation. Participants performed the 3-back, a test of working memory, at baseline, and during and immediately following stimulation on two days, separated by 24-48 hours. Active stimulation did not significantly enhance performance versus sham over the course of the experiment. However, exploratory comparisons did reveal a significant effect of stimulation group on performance during the first stimulation phase only, with active stimulation recipients performing better than sham. While these results do not support the hypothesis that dorsolateral prefrontal cortex tDCS boosts working memory, they raise the possibility that its effects may be greatest during early learning stages.

scholarly journals Does excitatory fronto-extracephalic tDCS lead to improved working memory performance?

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 219 ◽  
Author(s):  
Níall Lally ◽  
Camilla L. Nord ◽  
Vincent Walsh ◽  
Jonathan P. Roiser
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Memory Performance ◽  
Reference Electrode ◽  
Double Blind ◽  
Non Invasive ◽  
Stimulation Parameters ◽  
Dorsolateral Prefrontal ◽  
Better Than

Evidence suggests that excitatory transcranial direct current stimulation (tDCS) may improve performance on a wide variety of cognitive tasks. Due to the non-invasive and inexpensive nature of the method, harnessing its potential could be particularly useful for the treatment of neuropsychiatric illnesses involving cognitive dysfunction. However, questions remain regarding the efficacious stimulation parameters. Here, using a double-blind between-subjects design, we explored whether 1 mA excitatory (anodal) left dorsolateral prefrontal cortex stimulation with a contralateral extracephalic reference electrode, leads to enhanced working memory performance across two days, relative to sham stimulation. Participants performed the 3-back, a test of working memory, at baseline, and during and immediately following stimulation on two days, separated by 24-48 hours. Active stimulation did not significantly enhance performance versus sham over the course of the experiment. However, exploratory comparisons did reveal a significant effect of stimulation group on performance during the first stimulation phase only, with active stimulation recipients performing better than sham. While these results do not support the hypothesis that dorsolateral prefrontal cortex tDCS boosts working memory, they raise the possibility that its effects may be greatest during early learning stages.

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