scholarly journals The Precentral Gyrus Contributions to the Early Time-Course of Grapheme-to-Phoneme Conversion

2021 ◽  
pp. 1-61
Author(s):  
Erik Kaestner ◽  
Xiaojing Wu ◽  
Daniel Friedman ◽  
Patricia Dugan ◽  
Orrin Devinsky ◽  
...  
Keyword(s):  
Letter String ◽  
Time Course ◽  
Phase Locking ◽  
Silent Reading ◽  
Early Time ◽  
Superior Temporal Gyrus ◽  
Precentral Gyrus ◽  
High Concentration ◽  
High Gamma ◽  
Pars Opercularis

Abstract As part of silent reading models, visual orthographic information is transduced into an auditory phonological code in a process of grapheme-to-phoneme conversion (GPC). This process is often identified with lateral temporal-parietal regions associated with auditory phoneme encoding. However, the role of articulatory phonemic representations and the precentral gyrus in GPC is ambiguous. Though the precentral gyrus is implicated in many functional MRI studies of reading, it is not clear if the time course of activity in this region is consistent with the precentral gyrus being involved in GPC. We recorded cortical electrophysiology during a bimodal match/mismatch task from eight patients with perisylvian subdural electrodes to examine the time course of neural activity during a task which necessitated GPC. Patients made a match/mismatch decision between a three-letter string and the following auditory bi-phoneme. We characterized the distribution and timing of evoked broadband high gamma (BHG; 70–170 Hz) as well as phase-locking between electrodes. The precentral gyrus emerged with a high concentration of broadband high gamma responses to visual and auditory language as well as mismatch effects. The pars opercularis, supramarginal gyrus, and superior temporal gyrus were also involved. The precentral gyrus showed strong phase-locking with the caudal fusiform gyrus during letter-string presentation and with surrounding perisylvian cortex during the bimodal visual-auditory comparison period. These findings hint at a role for precentral cortex in transducing visual into auditory codes during silent reading.

scholarly journals An Intracranial EEG Study of Visual Language Encoding: The Contribution of the Precentral Gyrus to Silent Reading

2021 ◽  
pp. 1-18
Author(s):  
Erik Kaestner ◽  
Thomas Thesen ◽  
Orrin Devinsky ◽  
Werner Doyle ◽  
Chad Carlson ◽  
...  
Keyword(s):  
Semantic Processing ◽  
Phase Locking ◽  
Silent Reading ◽  
Decision Task ◽  
Precentral Gyrus ◽  
Large Patient ◽  
High Gamma ◽  
Gamma Power ◽  
Spatio Temporal ◽  
Models Of Reading

Abstract Models of reading emphasize that visual (orthographic) processing provides input to phonological as well as lexical–semantic processing. Neurobiological models of reading have mapped these processes to distributed regions across occipital–temporal, temporal–parietal, and frontal cortices. However, the role of the precentral gyrus in these models is ambiguous. Articulatory phonemic representations in the precentral gyrus are obviously involved in reading aloud, but it is unclear if the precentral gyrus is recruited during reading silently in a time window consistent with participation in phonological processing contributions. Here, we recorded intracranial electrophysiology during a speeded semantic decision task from 24 patients to map the spatio-temporal flow of information across the cortex during silent reading. Patients selected animate nouns from a stream of nonanimate words, letter strings, and false-font stimuli. We characterized the distribution and timing of evoked high-gamma power (70–170 Hz) as well as phase-locking between electrodes. The precentral gyrus showed a proportion of electrodes responsive to linguistic stimuli (27%) that was at least as high as those of surrounding peri-sylvian regions. These precentral gyrus electrodes had significantly greater high-gamma power for words compared to both false-font and letter-string stimuli. In a patient with word-selective effects in the fusiform, superior temporal, and precentral gyri, there was significant phase-locking between the fusiform and precentral gyri starting at ∼180 msec and between the precentral and superior temporal gyri starting at ∼220 msec. Finally, our large patient cohort allowed exploratory analyses of the spatio-temporal reading network underlying silent reading. The distribution, timing, and connectivity results place the precentral gyrus as an important hub in the silent reading network.

Cerebral Cortical Representation of Automatic and Volitional Swallowing in Humans

2001 ◽  
Vol 85 (2) ◽  
pp. 938-950 ◽  
Author(s):  
Ruth E. Martin ◽  
Bradley G. Goodyear ◽  
Joseph S. Gati ◽  
Ravi S. Menon
Keyword(s):  
Time Course ◽  
Right Hemisphere ◽  
Functional Organization ◽  
Thyroid Cartilage ◽  
Control Period ◽  
Superior Temporal Gyrus ◽  
Anterior Cingulate ◽  
Hemispheric Dominance ◽  
Cortical Representation ◽  
Precentral Gyrus

Although the cerebral cortex has been implicated in the control of swallowing, the functional organization of the human cortical swallowing representation has not been fully documented. Therefore, the present study determined the cortical representation of swallowing in fourteen healthy right-handed female subjects using single-event-related functional magnetic resonance imaging (fMRI). Subjects were scanned during three swallowing activation tasks: a naı̈ve saliva swallow, a voluntary saliva swallow, and a water bolus swallow. Swallow-related laryngeal movement was recorded simultaneously from the output of a bellows positioned over the thyroid cartilage. Statistical maps were generated by computing the difference between the magnitude of the voxel time course during 1) a single swallowing trial and 2) the corresponding control period. Automatic and volitional swallowing produced activation within several common cortical regions, the most prominent and consistent being located within the lateral precentral gyrus, lateral postcentral gyrus, and right insula. Activation foci within the superior temporal gyrus, middle and inferior frontal gyri, and frontal operculum also were identified for all swallowing tasks. In contrast, activation of the caudal anterior cingulate cortex was significantly more likely in association with the voluntary saliva swallow and water bolus swallow than the naı̈ve swallow. These findings support the view that, in addition to known brain stem areas, human swallowing is represented within a number of spatially and functionally distinct cortical loci which may participate differentially in the regulation of swallowing. Activation of the insula was significantly lateralized to the right hemisphere for the voluntary saliva swallow, suggesting a functional hemispheric dominance of the insula for the processing of swallowing.

Decline of contractility during ischemia-reperfusion injury: actin glutathionylation and its effect on allosteric interaction with tropomyosin

2006 ◽  
Vol 290 (3) ◽  
pp. C719-C727 ◽  
Author(s):  
Frank C. Chen ◽  
Ozgur Ogut
Keyword(s):  
Reperfusion Injury ◽  
Posttranslational Modifications ◽  
Actin Polymerization ◽  
Time Course ◽  
Troponin I ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
High Concentration ◽  
Cross Sectional ◽  
The Impact

The severity and duration of ischemia-reperfusion injury is hypothesized to play an important role in the ability of the heart subsequently to recover contractility. Permeabilized trabeculae were prepared from a rat model of ischemia-reperfusion injury to examine the impact on force generation. Compared with the control perfused condition, the maximum force (Fmax) per cross-sectional area and the rate of tension redevelopment of Ca2+-activated trabeculae fell by 71% and 44%, respectively, during ischemia despite the availability of a high concentration of ATP. The reduction in Fmax with ischemia was accompanied by a decline in fiber stiffness, implying a drop in the absolute number of attached cross bridges. However, the declines during ischemia were largely recovered after reperfusion, leading to the hypothesis that intrinsic, reversible posttranslational modifications to proteins of the contractile filaments occur during ischemia-reperfusion injury. Examination of thin-filament proteins from ischemic or ischemia-reperfused hearts did not reveal proteolysis of troponin I or T. However, actin was found to be glutathionylated with ischemia. Light-scattering experiments demonstrated that glutathionylated G-actin did not polymerize as efficiently as native G-actin. Although tropomyosin accelerated the time course of native and glutathionylated G-actin polymerization, the polymerization of glutathionylated G-actin still lagged native G-actin at all concentrations of tropomyosin tested. Furthermore, cosedimentation experiments demonstrated that tropomyosin bound glutathionylated F-actin with significantly reduced cooperativity. Therefore, glutathionylated actin may be a novel contributor to the diverse set of posttranslational modifications that define the function of the contractile filaments during ischemia-reperfusion injury.

Perception and first defense responses against Pseudomonas syringae pv. phaseolicola in Phaseolus vulgaris L.: identification of Wall-Associated Kinase receptors

2021 ◽  
Author(s):  
Alfonso Gonzalo De la Rubia ◽  
María Luz Centeno ◽  
Victor Moreno-González ◽  
María De Castro ◽  
Penélope García-Angulo
Keyword(s):  
Phaseolus Vulgaris ◽  
Pseudomonas Syringae ◽  
Time Course ◽  
Early Time ◽  
Experimental System ◽  
Antioxidant Response ◽  
Defense Responses ◽  
Cellular Damage ◽  
Initial Increase ◽  
Phaseolus Vulgaris L

Common bean (Phaseolus vulgaris L.) is attacked by several pathogens such as the biotrophic gamma-proteobacterium Pseudomonas syringae pv. phaseolicola (Pph). In order to study the Pph-bean interaction during the first stages of infection, leaf disks of a susceptible bean variety named Riñón were infected with a pathogenic Pph. Using this experimental system, six new putative Wall-Associated Kinase (WAKs) receptors, previously identified in silico, were tested. These six bean WAKs (PvWAKs) showed high protein sequence homology to the well-described Arabidopsis WAK1 (AtWAK1) receptor and, by phylogenetic analysis, clustered together with AtWAKs. The expression of PvWAK1 increased at very early stages after the Pph infection. Time course experiments were performed to evaluate the accumulation of apoplastic H2O2, Ca2+ influx, total H2O2, antioxidant enzymatic activities, lipid peroxidation, and the concentrations of abscisic acid (ABA) and salicylic acid (SA), as well as the expression of six defense-related genes – MEKK-1, MAPKK, WRKY33, RIN4, PR1 and NPR1. The results showed that overexpression of PR1 occurred 2 h after Pph infection without a concomitant increase in SA levels. Although apoplastic H2O2 increased after infection, the oxidative burst was neither intense nor rapid and an efficient antioxidant response did not occur, suggesting that the observed cellular damage was due to the initial increase in total H2O2 at early time points after infection. In conclusion, the Riñón variety can perceive the presence of Pph, but this recognition only results in a modest and slow activation of host defenses, leading to high susceptibility to Pph.

Copper metabolism in the kidney of rats administered copper and copper-metallothionein

1998 ◽  
Vol 274 (4) ◽  
pp. F783-F790 ◽  
Author(s):  
Masaaki Kurasaki ◽  
Masashi Okabe ◽  
Shigeru Saito ◽  
Mika Suzuki-Kurasaki
Keyword(s):  
Time Course ◽  
Copper Metabolism ◽  
Degradation Process ◽  
High Concentration ◽  
Tubular Cells ◽  
Microscopic Studies

To gain a greater understanding of the mechanism of Cu metabolism in kidneys of rats, using autofluorescence of Cu-metallothioneins (Cu-MTs) we revealed the behavior of Cu-MT in the kidneys of rats administered Cu-MT. Yellow and orange fluorescent signals of Cu-MT were observed in the cortex. By microscopic studies, Cu-MT was dominant in the proximal convolute tubular cells of the cortex. A high concentration of Cu-MT presented in the lysosome-like organelles of the proximal convolute tubular adjacent to the glomeruli. During the time course after the injection, the orange signal in lysosome-like organelles gradually converted to a yellow signal, indicating that the Cu-MT was involved in a degradation process in lysosomes by oxidation, and the MT mRNA increased in the cortex, although the immunoreactivity of MT was almost constant in the same region. These results suggested that Cu bound to the injected MT was released in lysosomes and became a new inducer of MT biosynthesis in the cortex. In conclusion, the biosynthesis and degradation of Cu-MT occur repeatedly in the proximal convolute tubular cells.

Early time course of myocardial electrical impedance during acute coronary artery occlusion in pigs, dogs, and humans

2005 ◽  
Vol 99 (4) ◽  
pp. 1576-1581 ◽  
Author(s):  
Carlos L. del Rio ◽  
Patrick I. McConnell ◽  
Bradley D. Clymer ◽  
Roger Dzwonczyk ◽  
Robert E. Michler ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Time Course ◽  
Electrical Impedance ◽  
Early Time ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Acute Ischemia ◽  
Collateral Flow ◽  
Total Occlusion ◽  
Interspecies Differences

Changes in myocardial electrical impedance (MEI) and physiological end points have been correlated during acute ischemia. However, the importance of MEI's early time course is not clear. This study evaluates such significance, by comparing the temporal behavior of MEI during acute total occlusion of the left anterior descending coronary artery in anesthetized humans, dogs, and pigs. Here, interspecies differences in three MEI parameters (baseline, time to plateau onset, and plateau value normalized by baseline) were evaluated using Kruskal-Wallis ANOVA and post hoc tests ( P < 0.05). Noteworthy differences in the MEI time to plateau onset were observed: In dogs, MEI ischemic plateau was reached after 46.3 min (SD 12.9) min of occlusion, a significantly longer period compared with that of pigs and humans [4.7 (SD 1.2) and 4.1 min (SD 1.9), respectively]. However, no differences could be observed between both animal species regarding the normalized MEI ischemic plateau value (15.3% (SD 4.7) in pigs, vs. 19.6% (SD 2.6) in dogs). For all studied MEI parameters, only swine values resembled those of humans. The severity of myocardial supply ischemia, resulting from coronary artery occlusion, is known to be dependent on collateral flow. Thus, because dogs possess a well-developed collateral system (unlike humans or pigs), they have shown superior resistance to occlusion of a coronary artery. Here, the early MEI time course after left anterior descending coronary artery occlusion, represented by the time required to reach ischemic plateau, was proven to reflect such interspecies differences.

scholarly journals Prefrontal High Gamma in ECoG tags periodicity of musical rhythms in perception and imagination

2019 ◽  
Author(s):  
S. A. Herff ◽  
C. Herff ◽  
A. J. Milne ◽  
G. D. Johnson ◽  
J. J. Shih ◽  
...  
Keyword(s):  
Auditory Processing ◽  
Right Hemisphere ◽  
Brain Activity ◽  
Activity Patterns ◽  
Superior Temporal Gyrus ◽  
Gamma Activity ◽  
Rhythm Perception ◽  
High Gamma ◽  
The Right ◽  
Musical Rhythms

AbstractRhythmic auditory stimuli are known to elicit matching activity patterns in neural populations. Furthermore, recent research has established the particular importance of high-gamma brain activity in auditory processing by showing its involvement in auditory phrase segmentation and envelope-tracking. Here, we use electrocorticographic (ECoG) recordings from eight human listeners, to see whether periodicities in high-gamma activity track the periodicities in the envelope of musical rhythms during rhythm perception and imagination. Rhythm imagination was elicited by instructing participants to imagine the rhythm to continue during pauses of several repetitions. To identify electrodes whose periodicities in high-gamma activity track the periodicities in the musical rhythms, we compute the correlation between the autocorrelations (ACC) of both the musical rhythms and the neural signals. A condition in which participants listened to white noise was used to establish a baseline. High-gamma autocorrelations in auditory areas in the superior temporal gyrus and in frontal areas on both hemispheres significantly matched the autocorrelation of the musical rhythms. Overall, numerous significant electrodes are observed on the right hemisphere. Of particular interest is a large cluster of electrodes in the right prefrontal cortex that is active during both rhythm perception and imagination. This indicates conscious processing of the rhythms’ structure as opposed to mere auditory phenomena. The ACC approach clearly highlights that high-gamma activity measured from cortical electrodes tracks both attended and imagined rhythms.

scholarly journals Sensory perception in autism: an fMRI ALE meta-analysis

2020 ◽  
Author(s):  
Nazia Jassim ◽  
Simon Baron-Cohen ◽  
John Suckling
Keyword(s):  
Meta Analysis ◽  
Likelihood Estimation ◽  
Sensory Perception ◽  
Superior Temporal Gyrus ◽  
Occipital Cortex ◽  
Anterior Cingulate ◽  
Future Research ◽  
Precentral Gyrus ◽  
And Control ◽  
Lateral Occipital Cortex

Sensory sensitivities occur in up to 90% of autistic individuals. With the recent inclusion of sensory symptoms in the diagnostic criteria for autism, there is a current need to develop neural hypotheses related to autistic sensory perception. Using activation likelihood estimation (ALE), we meta-analysed 52 task-based fMRI studies investigating differences between autistic (n=891) and control (n=967) participants during non-social sensory perception. During complex perception, autistic groups showed more activity in the secondary somatosensory and occipital cortices, insula, caudate, superior temporal gyrus, and inferior parietal lobule, while control groups showed more activity in the frontal and parietal regions. During basic sensory processing, autistic groups showed hyperactivity in the lateral occipital cortex, primary somatosensory and motor cortices, insula, caudate, and thalamus, while controls showed heightened activity in the precentral gyrus, middle frontal gyrus, precuneus, and anterior cingulate cortex. We conclude that autistic individuals, on average, show distinct engagement of sensory-related brain networks during sensory perception. These findings may help guide future research to focus on relevant neurobiological mechanisms underpinning the autistic experience.

scholarly journals Hypoconnectivity networks in schizophrenia patients: a voxelwise meta-analysis of rs-fMRI

2021 ◽  
Author(s):  
Silvia Ruiz-Torras ◽  
Oscar Fernández-Vazquez ◽  
Cristina Cañete-Massé ◽  
Maribel Peró-Cebollero ◽  
Joan Guàrdia-Olmos
Keyword(s):  
Brain Connectivity ◽  
Meta Analysis ◽  
Superior Temporal Gyrus ◽  
Interesting Case ◽  
Control Group ◽  
Precentral Gyrus ◽  
Healthy Controls ◽  
Health States ◽  
The Right ◽  
Work Done

Abstract In the last few years, the field of brain connectivity has focused on identifying biomarkers to describe different health states and to discriminate between patients and healthy controls through the characterization of brain networks. A particularly interesting case, because of the symptoms' severity, is the work done with samples of patients diagnosed with schizophrenia. This meta-analysis aims to identify connectivity networks with different activation patterns between people diagnosed with schizophrenia and healthy controls. Therefore, we collected primary studies exploring whole brain connectivity by functional magnetic resonance imaging at rest in patients with schizophrenia compared to healthy people. Thus, we identified 25 high-quality studies that included a total of 1285 people with schizophrenia and 1279 healthy controls. The results indicate hypoactivation in the right precentral gyrus and in the left superior temporal gyrus of people with schizophrenia compared with the control group. These regions have been linked to deficits in gesticulation and the experience of auditory hallucinations in people with schizophrenia. A study of heterogeneity demonstrated that the effect size was influenced by the sample size and type of analysis. These results imply new contributions to the knowledge, diagnosis, and treatment of schizophrenia both clinically and in research.

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