scholarly journals Low-frequency direct cortical stimulation of left superior frontal gyrus enhances working memory performance

NeuroImage ◽  
2019 ◽  
Vol 184 ◽  
pp. 697-706 ◽  
Author(s):  
Sankaraleengam Alagapan ◽  
Caroline Lustenberger ◽  
Eldad Hadar ◽  
Hae Won Shin ◽  
Flavio Frӧhlich
Keyword(s):  
Working Memory ◽  
Memory Performance ◽  
Low Frequency ◽  
Cortical Stimulation ◽  
Superior Frontal Gyrus ◽  
Direct Cortical Stimulation ◽  
Stimulation Of

scholarly journals Low-frequency direct cortical stimulation of left superior frontal gyrus enhances working memory performance

2018 ◽  
Author(s):  
Sankaraleengam Alagapan ◽  
Caroline Lustenberger ◽  
Eldad Hadar ◽  
Hae Won Shin ◽  
Flavio Fröhlich
Keyword(s):  
Working Memory ◽  
Memory Performance ◽  
Reaction Times ◽  
Low Frequency ◽  
Cortical Stimulation ◽  
Superior Frontal Gyrus ◽  
Frequency Bands ◽  
Direct Cortical Stimulation ◽  
Cortical Oscillations

AbstractThe neural substrates of working memory are spread across prefrontal, parietal and cingulate cortices and are thought to be coordinated through low frequency cortical oscillations in the theta (3 – 8 Hz) and alpha (8 – 12 Hz) frequency bands. While the functional role of many subregions have been elucidated using neuroimaging studies, the role of superior frontal gyrus (SFG) is not yet clear. Here, we combined electrocorticography and direct cortical stimulation in three patients implanted with subdural electrodes to assess if superior frontal gyrus is indeed involved in working memory. We found left SFG exhibited task-related modulation of oscillations in the theta and alpha frequency bands specifically during the encoding epoch. Stimulation at the frequency matched to the endogenous oscillations resulted in reduced reaction times in all three participants. Our results support the causal role of SFG in working memory and suggest that SFG may coordinate working memory through low-frequency oscillations thus bolstering the feasibility of targeting oscillations for restoring cognitive function.

scholarly journals Network-Targeted, Multi-site Direct Cortical Stimulation Enhances Working Memory by Modulating Phase Lag of Low-Frequency Oscillations

Cell Reports ◽  
2019 ◽  
Vol 29 (9) ◽  
pp. 2590-2598.e4 ◽  
Author(s):  
Sankaraleengam Alagapan ◽  
Justin Riddle ◽  
Wei Angel Huang ◽  
Eldad Hadar ◽  
Hae Won Shin ◽  
...  
Keyword(s):  
Working Memory ◽  
Low Frequency ◽  
Cortical Stimulation ◽  
Phase Lag ◽  
Direct Cortical Stimulation ◽  
Low Frequency Oscillations

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 Modulation of Cortical Oscillations by Low-Frequency Direct Cortical Stimulation Is State-Dependent

PLoS Biology ◽  
2016 ◽  
Vol 14 (3) ◽  
pp. e1002424 ◽  
Author(s):  
Sankaraleengam Alagapan ◽  
Stephen L. Schmidt ◽  
Jérémie Lefebvre ◽  
Eldad Hadar ◽  
Hae Won Shin ◽  
...  
Keyword(s):  
Low Frequency ◽  
Cortical Stimulation ◽  
Direct Cortical Stimulation ◽  
Cortical Oscillations ◽  
State Dependent

scholarly journals Enhancement of Phonological Memory Following Transcranial Magnetic Stimulation (TMS)

2006 ◽  
Vol 17 (3-4) ◽  
pp. 187-194 ◽  
Author(s):  
Matthew P. Kirschen ◽  
Mathew S. Davis-Ratner ◽  
Thomas E. Jerde ◽  
Pam Schraedley-Desmond ◽  
John E. Desmond
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Memory Performance ◽  
Low Frequency ◽  
Behavioral Performance ◽  
Phonological Memory ◽  
Functional Magnetic Resonance ◽  
Phonological Store ◽  
The Brain ◽  
Stimulation Of

Phonologically similar items (mell, rell, gell) are more difficult to remember than dissimilar items (shen, floy, stap), likely because of mutual interference of the items in the phonological store. Low-frequency transcranial magnetic stimulation (TMS), guided by functional magnetic resonance imaging (fMRI) was used to disrupt this phonological confusion by stimulation of the left inferior parietal (LIP) lobule. Subjects received TMS or placebo stimulation while remembering sets of phonologically similar or dissimilar pseudo-words. Consistent with behavioral performance of patients with neurological damage, memory for phonologically similar, but not dissimilar, items was enhanced following TMS relative to placebo stimulation. Stimulation of a control region of the brain did not produce any changes in memory performance. These results provide new insights into how the brain processes verbal information by establishing the necessity of the inferior parietal region for optimal phonological storage. A mechanism is proposed for how TMS reduces phonological confusion and leads to facilitation of phonological memory.

scholarly journals The olfactory bulb modulates entorhinal cortex oscillations during spatial working memory

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Morteza Salimi ◽  
Farhad Tabasi ◽  
Milad Nazari ◽  
Sepideh Ghazvineh ◽  
Alireza Salimi ◽  
...  
Keyword(s):  
Working Memory ◽  
Olfactory Bulb ◽  
Entorhinal Cortex ◽  
Spatial Working Memory ◽  
Memory Performance ◽  
Memory Task ◽  
Low Frequency ◽  
Rhythmic Activity ◽  
Brain Regions ◽  
Simultaneous Recording

AbstractCognitive functions such as working memory require integrated activity among different brain regions. Notably, entorhinal cortex (EC) activity is associated with the successful working memory task. Olfactory bulb (OB) oscillations are known as rhythms that modulate rhythmic activity in widespread brain regions during cognitive tasks. Since the OB is structurally connected to the EC, we hypothesized that OB could modulate EC activity during working memory performance. Herein, we explored OB–EC functional connectivity during spatial working memory performance by simultaneous recording local field potentials when rats performed a Y-maze task. Our results showed that the coherence of delta, theta, and gamma-band oscillations between OB and EC was increased during correct trials compared to wrong trials. Cross-frequency coupling analyses revealed that the modulatory effect of OBs low-frequency phase on EC gamma power and phase was enhanced when animals correctly performed working memory task. The influx of information from OB to EC was also increased at delta and gamma bands within correct trials. These findings indicated that the modulatory influence of OB rhythms on EC oscillations might be necessary for successful working memory performance.

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