scholarly journals Oscillatory correlates of auditory working memory examined with human electrocorticography

2020 ◽  
Author(s):  
Sukhbinder Kumar ◽  
Phillip E. Gander ◽  
Joel I. Berger ◽  
Alexander J. Billig ◽  
Kirill V. Nourski ◽  
...  
Keyword(s):  
Working Memory ◽  
Auditory Cortex ◽  
Frontal Cortex ◽  
Low Frequency ◽  
Brain Regions ◽  
Delay Period ◽  
Blood Oxygenation ◽  
Oscillatory Activity ◽  
Frequency Bands ◽  
Inferior Frontal Cortex

AbstractThis work examines how sounds are held in auditory working memory (AWM) in humans by examining oscillatory local field potentials (LFPs) in candidate brain regions. Previous fMRI studies by our group demonstrated blood oxygenation level-dependent (BOLD) response increases during maintenance in auditory cortex, inferior frontal cortex and the hippocampus using a paradigm with a delay period greater than 10s. The relationship between such BOLD changes and ensemble activity in different frequency bands is complex, and the long delay period raised the possibility that long-term memory mechanisms were engaged. Here we assessed LFPs in different frequency bands in six subjects with recordings from all candidate brain regions using a paradigm with a short delay period of 3 s. Sustained delay activity was demonstrated in all areas, with different patterns in the different areas. Enhancement in low frequency (delta) power and suppression across higher frequencies (beta/gamma) were demonstrated in primary auditory cortex in medial Heschl’s gyrus (HG) whilst non-primary cortex showed patterns of enhancement and suppression that altered at different levels of the auditory hierarchy from lateral HG to superior- and middle-temporal gyrus. Inferior frontal cortex showed increasing suppression with increasing frequency. The hippocampus and parahippocampal gyrus showed low frequency increases and high frequency decreases in oscillatory activity. The work demonstrates sustained activity patterns that can only be explained by AWM maintenance, with prominent low-frequency increases in medial temporal lobe regions.

scholarly journals Network-targeted, multi-site direct cortical stimulation enhances working memory by modulating phase lag of low frequency oscillations

2019 ◽  
Author(s):  
Sankaraleengam Alagapan ◽  
Justin Riddle ◽  
Wei Angel Huang ◽  
Eldad Hadar ◽  
Hae Won Shin ◽  
...  
Keyword(s):  
Working Memory ◽  
Brain Stimulation ◽  
Effective Means ◽  
Low Frequency ◽  
Brain Regions ◽  
Phase Lag ◽  
Frequency Bands ◽  
Alpha Frequency ◽  
Cortical Regions ◽  
Parietal Cortices

AbstractWorking memory, an important component of cognitive control, is supported by the coordinated activation of a network of cortical regions in the frontal and parietal cortices. Oscillations in theta and alpha frequency bands are thought to coordinate these network interactions. Thus, targeting multiple nodes of the network with brain stimulation at the frequency of interaction may be an effective means of modulating working memory. We tested this hypothesis by identifying regions that are functionally connected in theta and alpha frequency bands and intracranially stimulating both regions simultaneously in participants undergoing invasive monitoring. We found that in-phase stimulation resulted in improvement in performance compared to sham stimulation. In contrast, anti-phase stimulation did not affect performance. In-phase stimulation resulted in decreased phase lag between regions within working memory network while anti-phase stimulation resulted in increased phase lag suggesting that shorter phase lag in oscillatory connectivity may lead to better performance. The results support the idea that phase lag may play a key role in information transmission across brain regions. More broadly, brain stimulation strategies that aim to improve cognition may be better served targeting multiple nodes of brain networks.

scholarly journals Disparity in interaural time difference improves the accuracy of neural representations of individual concurrent narrowband sounds in rat inferior colliculus and auditory cortex

2020 ◽  
Vol 123 (2) ◽  
pp. 695-706
Author(s):  
Lu Luo ◽  
Na Xu ◽  
Qian Wang ◽  
Liang Li
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Interaural Time Difference ◽  
Critical Role ◽  
Low Frequency ◽  
Time Difference ◽  
Neural Representation ◽  
Frequency Bands ◽  
Neural Segregation ◽  
Peripheral Auditory System

The central mechanisms underlying binaural unmasking for spectrally overlapping concurrent sounds, which are unresolved in the peripheral auditory system, remain largely unknown. In this study, frequency-following responses (FFRs) to two binaurally presented independent narrowband noises (NBNs) with overlapping spectra were recorded simultaneously in the inferior colliculus (IC) and auditory cortex (AC) in anesthetized rats. The results showed that for both IC FFRs and AC FFRs, introducing an interaural time difference (ITD) disparity between the two concurrent NBNs enhanced the representation fidelity, reflected by the increased coherence between the responses evoked by double-NBN stimulation and the responses evoked by single NBNs. The ITD disparity effect varied across frequency bands, being more marked for higher frequency bands in the IC and lower frequency bands in the AC. Moreover, the coherence between IC responses and AC responses was also enhanced by the ITD disparity, and the enhancement was most prominent for low-frequency bands and the IC and the AC on the same side. These results suggest a critical role of the ITD cue in the neural segregation of spectrotemporally overlapping sounds. NEW & NOTEWORTHY When two spectrally overlapped narrowband noises are presented at the same time with the same sound-pressure level, they mask each other. Introducing a disparity in interaural time difference between these two narrowband noises improves the accuracy of the neural representation of individual sounds in both the inferior colliculus and the auditory cortex. The lower frequency signal transformation from the inferior colliculus to the auditory cortex on the same side is also enhanced, showing the effect of binaural unmasking.

scholarly journals Theta oscillations in the prefrontal-hippocampal circuit do not couple to respiration-related oscillations

2021 ◽  
Author(s):  
Sunandha Srikanth ◽  
Dylan Le ◽  
Yudi Hu ◽  
Jill K Leutgeb ◽  
Stefan Leutgeb
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Learning And Memory ◽  
Long Range ◽  
Brain Regions ◽  
Theta Oscillations ◽  
Oscillatory Activity ◽  
Low Coherence ◽  
Theta Frequency ◽  
Neural Computations

Oscillatory activity is thought to coordinate neural computations across brain regions, and theta oscillations are critical for learning and memory. Because the frequency of respiratory-related oscillations (RROs) in rodents can overlap with the frequency of theta in the prefrontal cortex (PFC) and the hippocampus, we asked whether odor-cued working memory may be supported by coupling between these two oscillations. We first confirmed that RROs are propagated to the hippocampus and PFC and that RRO frequency overlaps with canonical theta frequency. However, we found low coherence between RROs and local theta oscillations in the hippocampus-PFC network when the two types of oscillations overlapped in frequency. This effect was observed during all behavioral phases including during movement and while odors were actively sampled when stationary. Despite the similarity in frequency, RROs and theta oscillations therefore appear to be limited to supporting computation in distinct networks, which suggests that sustained long-range coordination between oscillation patterns that depend on separate pacemakers is not necessary to support at least one type of working memory.

scholarly journals Brain Frequency-Specific Changes in the Spontaneous Neural Activity Are Associated With Cognitive Impairment in Patients With Presbycusis

2021 ◽  
Vol 13 ◽  
Author(s):  
Fuxin Ren ◽  
Wen Ma ◽  
Wei Zong ◽  
Ning Li ◽  
Xiao Li ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Auditory Cortex ◽  
Neural Activity ◽  
Auditory Processing ◽  
Low Frequency ◽  
Frontal Eye Field ◽  
Functional Coupling ◽  
Frequency Bands ◽  
Spontaneous Neural Activity ◽  
Key Nodes

Presbycusis (PC) is characterized by preferential hearing loss at high frequencies and difficulty in speech recognition in noisy environments. Previous studies have linked PC to cognitive impairment, accelerated cognitive decline and incident Alzheimer’s disease. However, the neural mechanisms of cognitive impairment in patients with PC remain unclear. Although resting-state functional magnetic resonance imaging (rs-fMRI) studies have explored low-frequency oscillation (LFO) connectivity or amplitude of PC-related neural activity, it remains unclear whether the abnormalities occur within all frequency bands or within specific frequency bands. Fifty-one PC patients and fifty-one well-matched normal hearing controls participated in this study. The LFO amplitudes were investigated using the amplitude of low-frequency fluctuation (ALFF) at different frequency bands (slow-4 and slow-5). PC patients showed abnormal LFO amplitudes in the Heschl’s gyrus, dorsolateral prefrontal cortex (dlPFC), frontal eye field and key nodes of the speech network exclusively in slow-4, which suggested that abnormal spontaneous neural activity in PC was frequency dependent. Our findings also revealed that stronger functional connectivity between the dlPFC and the posterodorsal stream of auditory processing, as well as lower functional coupling between the PCC and key nodes of the DMN, which were associated with cognitive impairments in PC patients. Our study might underlie the cross-modal plasticity and higher-order cognitive participation of the auditory cortex after partial hearing deprivation. Our findings indicate that frequency-specific analysis of ALFF could provide valuable insights into functional alterations in the auditory cortex and non-auditory regions involved in cognitive impairment associated with PC.

scholarly journals Functional synchronization between hippocampal sEEG, parietal ECoG and scalp EEG during a verbal working memory task

2020 ◽  
Author(s):  
Vasileios Dimakopoulos ◽  
Ece Boran ◽  
Peter Hilfiker ◽  
Lennart Stieglitz ◽  
Thomas Grunwald ◽  
...  
Keyword(s):  
Working Memory ◽  
Auditory Cortex ◽  
Information Flow ◽  
Verbal Working Memory ◽  
Oscillatory Activity ◽  
Functional Coupling ◽  
Maintenance Period ◽  
Physiological Basis ◽  
Cortical Areas ◽  
Scalp Eeg

ABSTRACTBackgroundThe maintenance of items in working memory (WM) relies on a widespread network of brain areas where synchronization between electrophysiological recordings may reflect functional coupling. While the coupling from hippocampus to scalp EEG is well established, we provide here direct cortical recordings for a fine-grained analysis.MethodsA patient performed a WM task where a string of letters was presented all at once, thus separating the encoding period from the maintenance period. We recorded sEEG from the hippocampus, temporo-parietal ECoG from a 64-contact grid electrode, and scalp EEG.ResultsPower spectral density (PSD) showed a clear task dependence: PSD in the posterior parietal lobe (10 Hz) and in the hippocampus (20 Hz) peaked towards the end of the maintenance period.Inter-area synchronization was characterized by the phase locking value (PLV). WM maintenance enhanced PLV between hippocampal sEEG and scalp EEG specifically in the theta range [6 7] Hz.PLV from hippocampus to parietal cortex increased during maintenance in the [9 10] Hz alpha and the 20 Hz range.When analyzing the information flow to and from auditory cortex by Granger causality, the flow was from auditory cortex to hippocampus with a peak in the [8 18] Hz range while letters were presented, and this flow was subsequently reversed during maintenance, while letters were maintained in memory.ConclusionsThe increased functional interaction between hippocampus and cortex through synchronized oscillatory activity and the directed information flow provide physiological basis for reverberation of memory items during maintenance. This points to a network for working memory that is bound by coherent oscillations involving cortical areas and hippocampus.SIGNIFICANCE STATEMENTHippocampal activity is known for its role in cognitive tasks involving episodic memory or spatial navigation, but its role in working memory and its sensitivity to workload is still under debate. Here, we investigated hippocampal and cortical activity while a subject maintained sets of letters in verbal working memory for a few seconds to guide action.After confirming the coupling between hippocampal oscillations and oscillations on the scalp, we found during maintenance that hippocampal oscillations increased coupling differentially to several areas of cortex by recording directly from the cortex.. During encoding of the letters, information flow was from auditory cortex to hippocampus and subsequently reversed during maintenance, thus providing a physiological basis for memory encoding and maintenance.This demonstrates a network for working memory that is bound by coherent oscillations that underlie the functional connectivity between cortical areas and hippocampus.

scholarly journals Interhemispheric Connectivity Supports Load-Dependent Working Memory Maintenance for Complex Visual Stimuli

2021 ◽  
Author(s):  
Chelsea Reichert Plaska ◽  
Jefferson Ortega ◽  
Bernard A. Gomes ◽  
Timothy M. Ellmore
Keyword(s):  
Working Memory ◽  
Phase Locking ◽  
Visual Stimuli ◽  
Load Condition ◽  
Brain Regions ◽  
Delay Period ◽  
Temporal Region ◽  
Verbal Rehearsal ◽  
Complex Stimuli ◽  
Low Load

AbstractAn open question in the working memory (WM) field is how information is kept online during the WM delay period. Maintenance of simple stimuli in WM is supported by connectivity between frontal and parietal brain regions. How does delay period activity and connectivity support WM of complex stimuli? Twenty-two participants completed a modified Sternberg WM task with complex stimuli and were told to remember either 2 (low-load) or 5 (high-load) scenes while 32- channel scalp EEG was recorded. During the 6-sec delay period 6 phase-scrambled scenes were presented, which served as interference. While increasing the WM load, particularly with complex stimuli, places a greater demand on attentional resources, interfering stimuli may hijack the available resources. This was confirmed in the examination of theta and alpha amplitude, as amplitude was reduced for the high WM load as compared with the low WM load across frontal, central, and parietal regions. Delay period connectivity was assessed with phase-locking value (PLV). We identified 3 supporting networks that facilitated performance for the low-load condition: 1) increased PLV between left frontal and right posterior temporal in the theta and alpha bands; 2) increased PLV between right anterior temporal and left central in the alpha and lower beta bands; and 3) increased PLV between left anterior temporal and left posterior temporal in theta, alpha, and lower beta bands for the low-load condition. These results suggest that these brain networks facilitated the low-load WM by filtering of interference and the use of verbal rehearsal during the delay period.Impact StatementAlthough, studies of working memory maintenance with simple stimuli have suggested a role of frontal-parietal networks in supporting maintenance, the current study suggests that maintenance of complex visual stimuli with interference present is supported by interhemispheric frontal-posterior temporal and intrahemispheric left temporal region connectivity. These networks support maintenance by filtering of the interfering stimuli, which facilitates the use of verbal rehearsal strategies during the delay period.

Stereotactic electroencephalography in humans reveals multisensory signal in early visual and auditory cortices

2019 ◽  
Author(s):  
Stefania Ferraro ◽  
Markus J. Van Ackeren ◽  
Roberto Mai ◽  
Laura Tassi ◽  
Francesco Cardinale ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Auditory Cortex ◽  
Auditory Processing ◽  
Multisensory Processing ◽  
Low Frequency ◽  
Event Related Potentials ◽  
Stimulus Onset ◽  
Oscillatory Activity ◽  
Visual Responses ◽  
Related Potentials

AbstractUnequivocally demonstrating the presence of multisensory signals at the earliest stages of cortical processing remains challenging in humans. In our study, we relied on the unique spatio-temporal resolution provided by intracranial stereotactic electroencephalographic (SEEG) recordings in patients with drug-resistant epilepsy to characterize the signal extracted from early visual (calcarine and pericalcarine) and auditory (Heschl’s gyrus and planum temporale) regions during a simple audio-visual oddball task. We provide evidences that both cross-modal responses (visual responses in auditory cortex or the reverse) and multisensory processing (alteration of the unimodal responses during bimodal stimulation) can be observed in intracranial event-related potentials (iERPs) and in power modulations of oscillatory activity at different temporal scales within the first 150 ms after stimulus onset. The temporal profiles of the iERPs are compatible with the hypothesis that MSI occurs by means of direct pathways linking early visual and auditory regions. Our data indicate, moreover, that MSI mainly relies on modulations of the low-frequency bands (foremost the theta band in the auditory cortex and the alpha band in the visual cortex), suggesting the involvement of feedback pathways between the two sensory regions. Remarkably, we also observed high-gamma power modulations by sounds in the early visual cortex, thus suggesting the presence of neuronal populations involved in auditory processing in the calcarine and pericalcarine region in humans.

scholarly journals Temporal Evolution of Oscillatory Activity Predicts Performance in a Choice-Reaction Time Reaching Task

2011 ◽  
Vol 105 (1) ◽  
pp. 18-27 ◽  
Author(s):  
Bernardo Perfetti ◽  
Clara Moisello ◽  
Eric C. Landsness ◽  
Svetlana Kvint ◽  
April Pruski ◽  
...  
Keyword(s):  
Reaction Time ◽  
Choice Reaction Time ◽  
Motor Planning ◽  
Low Frequency ◽  
Reaction Time Task ◽  
Cortical Activation ◽  
Reaching Movements ◽  
Oscillatory Activity ◽  
Frequency Bands ◽  
On Line

In this study, we characterized the patterns and timing of cortical activation of visually guided movements in a task with critical temporal demands. In particular, we investigated the neural correlates of motor planning and on-line adjustments of reaching movements in a choice-reaction time task. High-density electroencephalograohy (EEG, 256 electrodes) was recorded in 13 subjects performing reaching movements. The topography of the movement-related spectral perturbation was established across five 250-ms temporal windows (from prestimulus to postmovement) and five frequency bands (from theta to beta). Nine regions of interest were then identified on the scalp, and their activity was correlated with specific behavioral outcomes reflecting motor planning and on-line adjustments. Phase coherence analysis was performed between selected sites. We found that motor planning and on-line adjustments share similar topography in a fronto-parietal network, involving mostly low frequency bands. In addition, activities in the high and low frequency ranges have differential function in the modulation of attention with the former reflecting the prestimulus, top-down processes needed to promote timely responses, and the latter the planning and control of sensory-motor processes.

The role of inferior parietal and inferior frontal cortex in working memory.

2006 ◽  
Vol 20 (5) ◽  
pp. 529-538 ◽  
Author(s):  
Juliana V. Baldo ◽  
Nina F. Dronkers
Keyword(s):  
Working Memory ◽  
Frontal Cortex ◽  
Inferior Frontal Cortex

scholarly journals Multichannel brain recordings in behaving Drosophila reveal oscillatory activity and local coherence in response to sensory stimulation and circuit activation

2013 ◽  
Vol 110 (7) ◽  
pp. 1703-1721 ◽  
Author(s):  
Angelique C. Paulk ◽  
Yanqiong Zhou ◽  
Peter Stratton ◽  
Li Liu ◽  
Bruno van Swinderen
Keyword(s):  
Visual Stimulation ◽  
Sensory Modality ◽  
Field Potential ◽  
Brain Regions ◽  
Oscillatory Activity ◽  
Insect Brain ◽  
Sensory Stimuli ◽  
Multichannel Recording ◽  
Frequency Bands

Neural networks in vertebrates exhibit endogenous oscillations that have been associated with functions ranging from sensory processing to locomotion. It remains unclear whether oscillations may play a similar role in the insect brain. We describe a novel “whole brain” readout for Drosophila melanogaster using a simple multichannel recording preparation to study electrical activity across the brain of flies exposed to different sensory stimuli. We recorded local field potential (LFP) activity from >2,000 registered recording sites across the fly brain in >200 wild-type and transgenic animals to uncover specific LFP frequency bands that correlate with: 1) brain region; 2) sensory modality (olfactory, visual, or mechanosensory); and 3) activity in specific neural circuits. We found endogenous and stimulus-specific oscillations throughout the fly brain. Central (higher-order) brain regions exhibited sensory modality-specific increases in power within narrow frequency bands. Conversely, in sensory brain regions such as the optic or antennal lobes, LFP coherence, rather than power, best defined sensory responses across modalities. By transiently activating specific circuits via expression of TrpA1, we found that several circuits in the fly brain modulate LFP power and coherence across brain regions and frequency domains. However, activation of a neuromodulatory octopaminergic circuit specifically increased neuronal coherence in the optic lobes during visual stimulation while decreasing coherence in central brain regions. Our multichannel recording and brain registration approach provides an effective way to track activity simultaneously across the fly brain in vivo, allowing investigation of functional roles for oscillations in processing sensory stimuli and modulating behavior.

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