scholarly journals Widespread changes in firing rate and functional connectivity across the fronto-parietal network during rule guided working memory

2018 ◽  
Author(s):  
RF Salazar
Keyword(s):  
Working Memory ◽  
Functional Connectivity ◽  
Daily Lives ◽  
Rule Based ◽  
Match To Sample ◽  
Frontoparietal Network ◽  
Dorsolateral Prefrontal ◽  
Posterior Parietal ◽  
Matching Rules ◽  
Parietal Cortices

ABSTRACTFlexible rule-based behavior is an integral component of our daily lives. Rule dependent changes in the activity and functional connectivity of neurons in the frontoparietal network may underlie this flexibility. To test this idea, we simultaneously recorded neural activity from multiple areas in prefrontal and posterior parietal cortices of macaque monkeys while they performed a delayed match-to-sample task involving a non-instructed switch between location and identity matching rules. Our analysis revealed rule-dependent differences in firing rates during all phases of the task and marked task-dependent increases in spike count correlations with only weak differences between rules. These effects were widespread with a high incidence occurring within and between the dorsolateral prefrontal cortex, the lateral intraparietal area and area PG. We conclude that rule based visual working memory is associated with widespread modifications in excitability and functional connectivity across the frontoparietal network.

scholarly journals Enhancement of Visuospatial Working Memory by Transcranial Direct Current Stimulation (tDCS) on Prefrontal and Parietal Cortices

2021 ◽  
pp. 1-15
Author(s):  
Yousef Moghadas Tabrizi ◽  
◽  
Meysam Yavari Kateb ◽  
Shahnaz Shahrbanian ◽  
◽  
...  
Keyword(s):  
Working Memory ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Spatial Working Memory ◽  
Direct Current Stimulation ◽  
Frontoparietal Network ◽  
Dorsolateral Prefrontal ◽  
Posterior Parietal ◽  
The Right ◽  
Parietal Cortices

Objective: Previous studies have reported dorsolateral prefrontal cortex (DLPFC) and posterior parietal (PPC) activation during the performance of spatial working memory (SWM), so we decided to investigate the comparison of Transcranial Direct current stimulation (tDCS) effect between these two areas. Methods: Fifty-four healthy right-handed students (27 female, 27 male; age= 24.3±.2 years) were randomly assigned to anodal (N=27) and sham group (N= 27), each of these groups was further divided into F4 (representing right DLPFC) or P4 (representing right PPC) subgroups, respectively. A Computerized Corsi Block Tapping task has then used to measure spatial working memory. The t-DCS intervention consisted of five daily sessions with a direct current of 1.5 mA for 15 minutes over the F4 or P4 area of the brain at 24-hour intervals. Results: Significant enhancement of the SWM span as well as a faster response were seen after anodal tDCS in both the forward and backward direction. Moreover, the right DLPFC stimulation induced a faster reaction time compared to the right PPC. Conclusions: Both DLPFC and PP cortices stimulation, as an element of the frontoparietal network, showed SWM enhancement, with the DLPFC being more effected. Our finding provides new evidence for the comparison of the effect of stimulation on the two main activated cortical areas during visuospatial WM.

scholarly journals No evidence for changes in GABA concentration, functional connectivity, or working memory following continuous theta burst stimulation over dorsolateral prefrontal cortex

2021 ◽  
Author(s):  
Tribikram Thapa ◽  
Joshua Hendrikse ◽  
Sarah Thompson ◽  
Chao Suo ◽  
Mana Biabani ◽  
...  
Keyword(s):  
Working Memory ◽  
Functional Connectivity ◽  
Memory Performance ◽  
Memory Task ◽  
Low Frequency ◽  
Theta Burst Stimulation ◽  
Gaba Concentration ◽  
Dorsolateral Prefrontal ◽  
Theta Burst ◽  
Continuous Theta Burst Stimulation

Continuous theta burst stimulation (cTBS) is thought to reduce cortical excitability and modulate functional connectivity, possibly by altering cortical inhibition at the site of stimulation. However, most evidence comes from the motor cortex and it remains unclear whether similar effects occur following stimulation over other brain regions. We assessed whether cTBS over left dorsolateral prefrontal cortex altered gamma aminobutyric acid (GABA) concentration, functional connectivity and brain dynamics at rest, and brain activation and memory performance during a working memory task. Seventeen healthy individuals participated in a randomised, sham-controlled, cross-over experiment. Before and after either real or sham cTBS, magnetic resonance spectroscopy was obtained at rest to measure GABA concentrations, whereas functional magnetic resonance imaging (fMRI) was recorded at rest and during an n-back working memory task to measure functional connectivity, brain dynamics (low-frequency fluctuations), and task-related patterns of brain activity. We could not find evidence for changes in GABA concentration (P=0.66, Bayes factor [BF10]=0.07), resting-state functional connectivity (P(FWE)>0.05), resting-state low-frequency fluctuations (P=0.88, BF10=0.04), blood-oxygen level dependent activity during the n-back task (P(FWE) >0.05), or working memory performance (P=0.13, BF10=0.05) following real or sham cTBS. Our findings add to a growing body of literature suggesting the effects of cTBS are highly variable between individuals and question the notion that cTBS is a universal 'inhibitory' paradigm.

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 Distinct properties of layer 3 pyramidal neurons from prefrontal and parietal areas of the monkey neocortex

2019 ◽  
Author(s):  
Guillermo Gonzalez-Burgos ◽  
Takeaki Miyamae ◽  
Yosef Krimer ◽  
Yelena Gulchina ◽  
Diego Pafundo ◽  
...  
Keyword(s):  
Working Memory ◽  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Pyramidal Neurons ◽  
Spine Density ◽  
Cortical Areas ◽  
Basal Dendrites ◽  
Dorsolateral Prefrontal ◽  
Posterior Parietal ◽  
Memory Network

AbstractIn primates, working memory function depends on activity in a distributed network of cortical areas that display different patterns of delay task-related activity. These differences are correlated with, and might depend on, distinctive properties of the neurons located in each area. For example, layer 3 pyramidal neurons (L3PNs) differ significantly between primary visual and dorsolateral prefrontal (DLPFC) cortices. However, to what extent L3PNs differ between DLPFC and other association cortical areas is less clear. Hence, we compared the properties of L3PNs in monkey DLPFC versus posterior parietal cortex (PPC), a key node in the cortical working memory network. Using patch clamp recordings and biocytin cell filling in acute brain slices, we assessed the physiology and morphology of L3PNs from monkey DLPFC and PPC. The L3PN transcriptome was studied using laser microdissection combined with DNA microarray or quantitative PCR. We found that in both DLPFC and PPC, L3PNs were divided into regular spiking (RS-L3PNs) and bursting (B-L3PNs) physiological subtypes. Whereas regional differences in single-cell excitability were modest, B-L3PNs were rare in PPC (RS-L3PN:B-L3PN, 94:6), but were abundant in DLPFC (50:50), showing greater physiological diversity. Moreover, DLPFC L3PNs display larger and more complex basal dendrites with higher dendritic spine density. Additionally, we found differential expression of hundreds of genes, suggesting a transcriptional basis for the differences in L3PN phenotype between DLPFC and PPC. These data show that the previously observed differences between DLPFC and PPC neuron activity during working memory tasks are associated with diversity in the cellular/molecular properties of L3PNs.Significance statementIn the human and non-human primate neocortex, layer 3 pyramidal neurons (L3PNs) differ significantly between dorsolateral prefrontal (DLPFC) and sensory areas. Hence, L3PN properties reflect, and may contribute to, a greater complexity of computations performed in DLPFC. However, across association cortical areas, L3PN properties are largely unexplored. We studied the physiology, dendrite morphology and transcriptome of L3PNs from macaque monkey DLPFC and posterior parietal cortex (PPC), two key nodes in the cortical working memory network. L3PNs from DLPFC had greater diversity of physiological properties and larger basal dendrites with higher spine density. Moreover, transcriptome analysis suggested a molecular basis for the differences in the physiological and morphological phenotypes of L3PNs from DLPFC and PPC.

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