scholarly journals A face-selective ventral occipito-temporal map of the human brain with intracerebral potentials

2016 ◽  
Vol 113 (28) ◽  
pp. E4088-E4097 ◽  
Author(s):  
Jacques Jonas ◽  
Corentin Jacques ◽  
Joan Liu-Shuang ◽  
Hélène Brissart ◽  
Sophie Colnat-Coulbois ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Brain Activity ◽  
Temporal Cortex ◽  
Hemispheric Dominance ◽  
High Signal ◽  
Supporting Evidence ◽  
Fixed Rate ◽  
Susceptibility Artifacts ◽  
Regional Specialization ◽  
The Right

Human neuroimaging studies have identified a network of distinct face-selective regions in the ventral occipito-temporal cortex (VOTC), with a right hemispheric dominance. To date, there is no evidence for this hemispheric and regional specialization with direct measures of brain activity. To address this gap in knowledge, we recorded local neurophysiological activity from 1,678 contact electrodes implanted in the VOTC of a large group of epileptic patients (n = 28). They were presented with natural images of objects at a rapid fixed rate (six images per second: 6 Hz), with faces interleaved as every fifth stimulus (i.e., 1.2 Hz). High signal-to-noise ratio face-selective responses were objectively (i.e., exactly at the face stimulation frequency) identified and quantified throughout the whole VOTC. Face-selective responses were widely distributed across the whole VOTC, but also spatially clustered in specific regions. Among these regions, the lateral section of the right middle fusiform gyrus showed the largest face-selective response by far, offering, to our knowledge, the first supporting evidence of two decades of neuroimaging observations with direct neural measures. In addition, three distinct regions with a high proportion of face-selective responses were disclosed in the right ventral anterior temporal lobe, a region that is undersampled in neuroimaging because of magnetic susceptibility artifacts. A high proportion of contacts responding only to faces (i.e., “face-exclusive” responses) were found in these regions, suggesting that they contain populations of neurons involved in dedicated face-processing functions. Overall, these observations provide a comprehensive mapping of visual category selectivity in the whole human VOTC with direct neural measures.

scholarly journals Exact secure outage probability performance of uplinkdownlink multiple access network under imperfect CSI

2021 ◽  
Vol 10 (6) ◽  
pp. 3274-3281
Author(s):  
Dinh-Thuan Do ◽  
Minh-Sang Van Nguyen
Keyword(s):  
Outage Probability ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Access Network ◽  
Base Station ◽  
High Signal ◽  
Secrecy Outage Probability ◽  
Factors Affecting ◽  
Secrecy Outage ◽  
The Right

In this paper, we study uplink-downlink non-orthogonal multiple access (NOMA) systems by considering the secure performance at the physical layer. In the considered system model, the base station acts a relay to allow two users at the left side communicate with two users at the right side. By considering imperfect channel state information (CSI), the secure performance need be studied since an eavesdropper wants to overhear signals processed at the downlink. To provide secure performance metric, we derive exact expressions of secrecy outage probability (SOP) and and evaluating the impacts of main parameters on SOP metric. The important finding is that we can achieve the higher secrecy performance at high signal to noise ratio (SNR). Moreover, the numerical results demonstrate that the SOP tends to a constant at high SNR. Finally, our results show that the power allocation factors, target rates are main factors affecting to the secrecy performance of considered uplink-downlink NOMA systems.

scholarly journals The Menstrual Cycle Alters Resting-State Cortical Activity: A Magnetoencephalography Study

2021 ◽  
Vol 15 ◽  
Author(s):  
Rika Haraguchi ◽  
Hideyuki Hoshi ◽  
Sayuri Ichikawa ◽  
Mayuko Hanyu ◽  
Kohei Nakamura ◽  
...  
Keyword(s):  
Menstrual Cycle ◽  
Resting State ◽  
Functional Neuroimaging ◽  
Brain Activity ◽  
Temporal Cortex ◽  
Neural Oscillations ◽  
Median Frequency ◽  
Accurate Interpretation ◽  
High Gamma ◽  
The Right

Resting-state neural oscillations are used as biomarkers for functional diseases such as dementia, epilepsy, and stroke. However, accurate interpretation of clinical outcomes requires the identification and minimisation of potential confounding factors. While several studies have indicated that the menstrual cycle also alters brain activity, most of these studies were based on visual inspection rather than objective quantitative measures. In the present study, we aimed to clarify the effect of the menstrual cycle on spontaneous neural oscillations based on quantitative magnetoencephalography (MEG) parameters. Resting-state MEG activity was recorded from 25 healthy women with normal menstrual cycles. For each woman, resting-state brain activity was acquired twice using MEG: once during their menstrual period (MP) and once outside of this period (OP). Our results indicated that the median frequency and peak alpha frequency of the power spectrum were low, whereas Shannon spectral entropy was high, during the MP. Theta intensity within the right temporal cortex and right limbic system was significantly lower during the MP than during the OP. High gamma intensity in the left parietal cortex was also significantly lower during the MP than during the OP. Similar differences were also observed in the parietal and occipital regions between the proliferative (the late part of the follicular phase) and secretory phases (luteal phase). Our findings suggest that the menstrual cycle should be considered to ensure accurate interpretation of functional neuroimaging in clinical practice.

scholarly journals Imbalance between Emotionally Negative and Positive Life Events Retrieval and the Associated Asymmetry of Brain Activity

2019 ◽  
Vol 10 (1) ◽  
pp. 18
Author(s):  
Olga Razumnikova ◽  
Ekaterina Khoroshavtseva
Keyword(s):  
Life Events ◽  
Positive Emotions ◽  
Brain Activity ◽  
Negative Emotions ◽  
Temporal Cortex ◽  
Emotional Memory ◽  
Self Assessment ◽  
Posterior Cortex ◽  
Synchronization Effect ◽  
The Right

Sustained focusing on a negative assessment of life events can create negative background and changes in the emotional feedback to new information. In this regard, it is important to assess the balance between self-assessment of emotional memories and their reflection in brain activity. The study was aimed at exploring the brain activity using electroencephalographic (EEG) analysis in six frequency ranges from delta to beta2 during the retrieval of positive or negative emotional memory compared with the resting state. According to ANOVA results, the most informative for differentiation of emotions were the alpha2 and beta2 rhythms with greater synchronization effect for positive than for negative emotions. The memory retrieval, regardless of the valence of emotions, was accompanied by alpha1 desynchronization at the posterior cortex. Self-assessment of the memory intensity was not significantly different due to emotion valences. However, the scores of positive emotions were related positively with beta2 oscillations at the left anterior temporal site, whereas for negative emotions, at the right one. Thus, the emotional autobiographical memory is reflected by activation processes in the visual cortex and areas associated with multimodal information processing, whereas differentiation of the valence of emotions is presented by the high-frequency oscillations at the temporal cortex areas.

scholarly journals BRAIN ACTIVITY OF INDUSTRIAL DESIGNERS IN CONSTRAINED AND OPEN DESIGN: THE EFFECT OF GENDER ON FREQUENCY BANDS

2021 ◽  
Vol 1 ◽  
pp. 571-580
Author(s):  
Sonia Liliana da Silva Vieira ◽  
Mathias Benedek ◽  
John S. Gero ◽  
Gaetano Cascini ◽  
Shumin Li
Keyword(s):  
Prefrontal Cortex ◽  
Problem Solving ◽  
Design Research ◽  
Brain Activity ◽  
Temporal Cortex ◽  
Frequency Bands ◽  
Open Design ◽  
Main Effect ◽  
Industrial Designers ◽  
The Right

AbstractIn this paper, we present results from an experiment using EEG to measure brain activity and explore EEG frequency power associated with gender differences of professional industrial designers while performing two prototypical stages of constrained and open design tasks, problem-solving and design sketching. Results indicate no main effect of gender. However, among other main effects, a consistent main effect of hemisphere for the six frequency bands under analysis was found. In the problem-solving stage, male designers show higher alpha and beta bands in channels of the prefrontal cortices and female designers in the right occipitotemporal cortex and secondary visual cortices. In the design sketching stage, male designers show higher alpha and beta bands in the right prefrontal cortex, and female designers in the right temporal cortex and left prefrontal cortex, where higher theta is also found. Prioritising different cognitive functions seem to play a role in each gender's approach to constrained and open design tasks. Results can be useful to design professionals, students and design educators, and for the development of methodological approaches in design research and education.

scholarly journals Three dimensional microelectrodes enable high signal and spatial resolution for neural seizure recordings in brain slices and freely behaving animals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Wijdenes ◽  
K. Haider ◽  
C. Gavrilovici ◽  
B. Gunning ◽  
M. D. Wolff ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Signal To Noise Ratio ◽  
Brain Activity ◽  
Three Dimensional ◽  
Brain Slices ◽  
High Signal ◽  
Diagnostic Potential ◽  
Freely Behaving

AbstractNeural recordings made to date through various approaches—both in-vitro or in-vivo—lack high spatial resolution and a high signal-to-noise ratio (SNR) required for detailed understanding of brain function, synaptic plasticity, and dysfunction. These shortcomings in turn deter the ability to further design diagnostic, therapeutic strategies and the fabrication of neuro-modulatory devices with various feedback loop systems. We report here on the simulation and fabrication of fully configurable neural micro-electrodes that can be used for both in vitro and in vivo applications, with three-dimensional semi-insulated structures patterned onto custom, fine-pitch, high density arrays. These microelectrodes were interfaced with isolated brain slices as well as implanted in brains of freely behaving rats to demonstrate their ability to maintain a high SNR. Moreover, the electrodes enabled the detection of epileptiform events and high frequency oscillations in an epilepsy model thus offering a diagnostic potential for neurological disorders such as epilepsy. These microelectrodes provide unique opportunities to study brain activity under normal and various pathological conditions, both in-vivo and in in-vitro, thus furthering the ability to develop drug screening and neuromodulation systems that could accurately record and map the activity of large neural networks over an extended time period.

scholarly journals Mobile steady-state evoked potential recording: dissociable neural effects of real-world navigation and visual stimulation

2019 ◽  
Author(s):  
James Dowsett ◽  
Marianne Dieterich ◽  
Paul C.J. Taylor
Keyword(s):  
Steady State ◽  
Real World ◽  
Right Hemisphere ◽  
Visual Stimulation ◽  
Signal To Noise Ratio ◽  
Brain Activity ◽  
Neural Responses ◽  
Visual Hemifield ◽  
Wide Range ◽  
The Right

AbstractBackgroundThe ability to record brain activity in humans during movement, and in real world environments, is an important step towards understanding cognition. Electroencephalography (EEG) is well suited to mobile applications but suffers from the problem of artefacts introduced into the signal during movement. Steady state visually evoked potentials (SSVEPs) give an excellent signal-to-noise ratio and averaging a sufficient number of trials will eventually remove any noise not phase locked to the visual flicker.New MethodHere we present a method for producing SSVEPs of real world environments using modified LCD shutter glasses, which are commonly used for 3D TV, by adapting the lens to flicker at neurophysiologically relevant frequencies, in this case the alpha band. Participants viewed a room whilst standing and walking. Either the left or right side of the room was illuminated, to test if it is possible to recover the resulting SSVEPs when walking, as well as to probe the effect of walking on neural activity. Additionally, by using a signal generator to produce “simulated SSVEPs” on the scalp we can demonstrate that this method is able to accurately recover evoked neural responses during walking.ResultsThe amplitude of SSVEPs over right parietal cortex was reduced by walking. This finding is in line with converging evidence that visual-vestibular integration involves cortical lateralization with the right hemisphere being dominant in right handers. Furthermore, the waveform and phase of the SSVEPs is highly preserved between walking and standing, but was nevertheless sensitive to whether visual stimulation was presented to the left or right visual hemifield.ConclusionsThis method allows probing neural responses at a wide range of frequencies, during natural movements within real environments.

scholarly journals Versatile Surface Electrodes for Combined Electrophysiology and Two-Photon Imaging of the Mouse Central Nervous System

2021 ◽  
Vol 15 ◽  
Author(s):  
Michael Schweigmann ◽  
Laura C. Caudal ◽  
Gebhard Stopper ◽  
Anja Scheller ◽  
Klaus P. Koch ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Imaging Techniques ◽  
Brain Activity ◽  
Cell Types ◽  
High Signal ◽  
Neural Function ◽  
Two Photon ◽  
Cranial Window ◽  
Additional Stabilization

Understanding and modulating CNS function in physiological as well as pathophysiological contexts remains a significant ambition in research and clinical applications. The investigation of the multifaceted CNS cell types including their interactions and contributions to neural function requires a combination of the state-of-the-art in vivo electrophysiology and imaging techniques. We developed a novel type of liquid crystal polymer (LCP) surface micro-electrode manufactured in three customized designs with up to 16 channels for recording and stimulation of brain activity. All designs include spare central spaces for simultaneous 2P-imaging. Nanoporous platinum-plated contact sites ensure a low impedance and high current transfer. The epidural implantation of the LCP micro-electrodes could be combined with standard cranial window surgery. The epidurally positioned electrodes did not only display long-term biocompatibility, but we also observed an additional stabilization of the underlying CNS tissue. We demonstrate the electrode’s versatility in combination with in vivo 2P-imaging by monitoring anesthesia-awake cycles of transgenic mice with GCaMP3 expression in neurons or astrocytes. Cortical stimulation and simultaneous 2P Ca2+ imaging in neurons or astrocytes highlighted the astrocytes’ integrative character in neuronal activity processing. Furthermore, we confirmed that spontaneous astroglial Ca2+ signals are dampened under anesthesia, while evoked signals in neurons and astrocytes showed stronger dependency on stimulation intensity rather than on various levels of anesthesia. Finally, we show that the electrodes provide recordings of the electrocorticogram (ECoG) with a high signal-to noise ratio and spatial signal differences which help to decipher brain activity states during experimental procedures. Summarizing, the novel LCP surface micro-electrode is a versatile, convenient, and reliable tool to investigate brain function in vivo.

scholarly journals μ-rhythm extracted with personalized EEG filters correlates with corticospinal excitability in real-time phase-triggered EEG-TMS

2018 ◽  
Author(s):  
Natalie Schaworonkow ◽  
Pedro Caldana Gordon ◽  
Paolo Belardinelli ◽  
Ulf Ziemann ◽  
Til Ole Bergmann ◽  
...  
Keyword(s):  
Real Time ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Signal To Noise Ratio ◽  
Brain Activity ◽  
Single Pulse ◽  
Extraction Methods ◽  
Brain Regions ◽  
High Signal

AbstractOngoing brain activity has been implicated in the modulation of cortical excitability. The combination of electroencephalography (EEG) and transcranial magnetic stimulation (TMS) in a real-time triggered setup is a novel method for testing hypotheses about the relationship between spontaneous neuronal oscillations, cortical excitability, and synaptic plasticity. For this method, a reliable real-time extraction of the neuronal signal of interest from scalp EEG with high signal-to-noise ratio (SNR) is of crucial importance. Here we compare individually tailored spatial filters as computed by spatial-spectral decomposition (SSD), which maximizes SNR in a frequency band of interest, against established local C3-centered Laplacian filters for the extraction of the sensorimotor μ-rhythm. Single-pulse TMS over the left primary motor cortex was synchronized with the surface positive or negative peak of the respective extracted signal, and motor evoked potentials (MEP) were recorded with electromyography (EMG) of a contralateral hand muscle. Both extraction methods led to a comparable degree of MEP amplitude modulation by phase of the sensorimotor μ-rhythm at the time of stimulation. This could be relevant for targeting other brain regions with no working benchmark such as the local C3-centered Laplacian filter, as sufficient SNR is an important prerequisite for reliable real-time single-trial detection of EEG features.

scholarly journals For Better or Worse: The Effect of Prismatic Adaptation on Auditory Neglect

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Isabel Tissieres ◽  
Mona Elamly ◽  
Stephanie Clarke ◽  
Sonia Crottaz-Herbette
Keyword(s):  
Dichotic Listening ◽  
Temporal Cortex ◽  
Auditory Localization ◽  
Hemispheric Dominance ◽  
Complex Nature ◽  
Negative Effects ◽  
Visuospatial Neglect ◽  
Attentional System ◽  
The Right ◽  
Prismatic Adaptation

Patients with auditory neglect attend less to auditory stimuli on their left and/or make systematic directional errors when indicating sound positions. Rightward prismatic adaptation (R-PA) was repeatedly shown to alleviate symptoms of visuospatial neglect and once to restore partially spatial bias in dichotic listening. It is currently unknown whether R-PA affects only this ear-related symptom or also other aspects of auditory neglect. We have investigated the effect of R-PA on left ear extinction in dichotic listening, space-related inattention assessed by diotic listening, and directional errors in auditory localization in patients with auditory neglect. The most striking effect of R-PA was the alleviation of left ear extinction in dichotic listening, which occurred in half of the patients with initial deficit. In contrast to nonresponders, their lesions spared the right dorsal attentional system and posterior temporal cortex. The beneficial effect of R-PA on an ear-related performance contrasted with detrimental effects on diotic listening and auditory localization. The former can be parsimoniously explained by the SHD-VAS model (shift in hemispheric dominance within the ventral attentional system; Clarke and Crottaz-Herbette 2016), which is based on the R-PA-induced shift of the right-dominant ventral attentional system to the left hemisphere. The negative effects in space-related tasks may be due to the complex nature of auditory space encoding at a cortical level.

Emotional Reactivity to Visual Content as Revealed by ERP Component Clustering

2015 ◽  
Vol 29 (4) ◽  
pp. 135-146 ◽  
Author(s):  
Miroslaw Wyczesany ◽  
Szczepan J. Grzybowski ◽  
Jan Kaiser
Keyword(s):  
Emotional Reactivity ◽  
Brain Activity ◽  
Affective State ◽  
Occipital Lobe ◽  
Stimulus Onset ◽  
Emotional States ◽  
Neural Basis ◽  
Temporoparietal Junction ◽  
The Right ◽  
The Impact

Abstract. In the study, the neural basis of emotional reactivity was investigated. Reactivity was operationalized as the impact of emotional pictures on the self-reported ongoing affective state. It was used to divide the subjects into high- and low-responders groups. Independent sources of brain activity were identified, localized with the DIPFIT method, and clustered across subjects to analyse the visual evoked potentials to affective pictures. Four of the identified clusters revealed effects of reactivity. The earliest two started about 120 ms from the stimulus onset and were located in the occipital lobe and the right temporoparietal junction. Another two with a latency of 200 ms were found in the orbitofrontal and the right dorsolateral cortices. Additionally, differences in pre-stimulus alpha level over the visual cortex were observed between the groups. The attentional modulation of perceptual processes is proposed as an early source of emotional reactivity, which forms an automatic mechanism of affective control. The role of top-down processes in affective appraisal and, finally, the experience of ongoing emotional states is also discussed.

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