scholarly journals Unexpected sound omissions are signaled in human posterior superior temporal gyrus: an intracranial study

2019 ◽  
Author(s):  
Yvonne M. Fonken ◽  
Arjun Mukerji ◽  
Richard Jimenez ◽  
Jack Lin ◽  
Peter Brunner ◽  
...  
Keyword(s):  
Sensory Processing ◽  
High Frequency ◽  
Refractory Epilepsy ◽  
Superior Temporal Gyrus ◽  
Behavioral Performance ◽  
Prediction Errors ◽  
Electrophysiological Signals ◽  
Evoked Activity ◽  
Sensory Neural ◽  
High Level

AbstractContext modulates sensory neural activations enhancing perceptual and behavioral performance and reducing prediction errors. However, the mechanism of when and where these high-level expectations act on sensory processing is unclear. Here, we isolate the effect of expectation absent any auditory evoked activity by assessing the response to omitted expected sounds. Electrophysiological signals were recorded directly from the superior temporal gyrus (STG) and superior temporal sulcus (STS) in patients with medically refractory epilepsy. Subjects listened to a predictable sequence of syllables, with some infrequently omitted. We found a high frequency band (HFB, 70-150Hz) response to omissions, which overlap with a posterior subset of auditory active electrodes. This response is distinct from omission activations observed in non-auditory selective sites in STG. Heard syllables could be classified reliably from STG, but not the identity of the omitted stimulus. Both omission- and target detection activations were also observed in prefrontal cortex.We propose that the posterior STG and STS are central for implementing predictions in the auditory environment. HFB omission activations in this region appear to index mismatch-signaling or salience detection processes.

scholarly journals Dynamic relationships between spontaneous and evoked electrophysiological activity

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Soren Wainio-Theberge ◽  
Annemarie Wolff ◽  
Georg Northoff
Keyword(s):  
Neural Activity ◽  
Large Scale ◽  
Behavioral Outcomes ◽  
Low Frequencies ◽  
Scale Free ◽  
Non Invasive ◽  
Spontaneous Neural Activity ◽  
Electrophysiological Signals ◽  
Evoked Activity ◽  
Dynamic Relationships

AbstractSpontaneous neural activity fluctuations have been shown to influence trial-by-trial variation in perceptual, cognitive, and behavioral outcomes. However, the complex electrophysiological mechanisms by which these fluctuations shape stimulus-evoked neural activity remain largely to be explored. Employing a large-scale magnetoencephalographic dataset and an electroencephalographic replication dataset, we investigate the relationship between spontaneous and evoked neural activity across a range of electrophysiological variables. We observe that for high-frequency activity, high pre-stimulus amplitudes lead to greater evoked desynchronization, while for low frequencies, high pre-stimulus amplitudes induce larger degrees of event-related synchronization. We further decompose electrophysiological power into oscillatory and scale-free components, demonstrating different patterns of spontaneous-evoked correlation for each component. Finally, we find correlations between spontaneous and evoked time-domain electrophysiological signals. Overall, we demonstrate that the dynamics of multiple electrophysiological variables exhibit distinct relationships between their spontaneous and evoked activity, a result which carries implications for experimental design and analysis in non-invasive electrophysiology.

scholarly journals Circuit mechanisms encoding odors and driving aging-associated behavioral declines in Caenorhabditis elegans

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Sarah G Leinwand ◽  
Claire J Yang ◽  
Daphne Bazopoulou ◽  
Nikos Chronis ◽  
Jagan Srinivasan ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Sensory Neurons ◽  
Neural Activity ◽  
Chemical Cues ◽  
Primary Neurons ◽  
Olfactory Neurons ◽  
Odor Concentration ◽  
Evoked Activity ◽  
Sensory Neural ◽  
Extract Information

Chemosensory neurons extract information about chemical cues from the environment. How is the activity in these sensory neurons transformed into behavior? Using Caenorhabditis elegans, we map a novel sensory neuron circuit motif that encodes odor concentration. Primary neurons, AWCON and AWA, directly detect the food odor benzaldehyde (BZ) and release insulin-like peptides and acetylcholine, respectively, which are required for odor-evoked responses in secondary neurons, ASEL and AWB. Consistently, both primary and secondary neurons are required for BZ attraction. Unexpectedly, this combinatorial code is altered in aged animals: odor-evoked activity in secondary, but not primary, olfactory neurons is reduced. Moreover, experimental manipulations increasing neurotransmission from primary neurons rescues aging-associated neuronal deficits. Finally, we correlate the odor responsiveness of aged animals with their lifespan. Together, these results show how odors are encoded by primary and secondary neurons and suggest reduced neurotransmission as a novel mechanism driving aging-associated sensory neural activity and behavioral declines.

scholarly journals Cochlear compound action potentials from high-level tone bursts originate from wide cochlear regions that are offset toward the most sensitive cochlear region

2019 ◽  
Vol 121 (3) ◽  
pp. 1018-1033 ◽  
Author(s):  
C. Lee ◽  
J. J. Guinan ◽  
M. A. Rutherford ◽  
W. A. Kaf ◽  
K. M. Kennedy ◽  
...  
Keyword(s):  
High Frequency ◽  
Action Potentials ◽  
Tuning Curve ◽  
Low Frequency ◽  
Sound Level ◽  
Frequency Tone ◽  
Compound Action Potentials ◽  
High Level ◽  
Level Tone ◽  
Compound Action

Little is known about the spatial origins of auditory nerve (AN) compound action potentials (CAPs) evoked by moderate to intense sounds. We studied the spatial origins of AN CAPs evoked by 2- to 16-kHz tone bursts at several sound levels by slowly injecting kainic acid solution into the cochlear apex of anesthetized guinea pigs. As the solution flowed from apex to base, it sequentially reduced CAP responses from low- to high-frequency cochlear regions. The times at which CAPs were reduced, combined with the cochlear location traversed by the solution at that time, showed the cochlear origin of the removed CAP component. For low-level tone bursts, the CAP origin along the cochlea was centered at the characteristic frequency (CF). As sound level increased, the CAP center shifted basally for low-frequency tone bursts but apically for high-frequency tone bursts. The apical shift was surprising because it is opposite the shift expected from AN tuning curve and basilar membrane motion asymmetries. For almost all high-level tone bursts, CAP spatial origins extended over 2 octaves along the cochlea. Surprisingly, CAPs evoked by high-level low-frequency (including 2 kHz) tone bursts showed little CAP contribution from CF regions ≤ 2 kHz. Our results can be mostly explained by spectral splatter from the tone-burst rise times, excitation in AN tuning-curve “tails,” and asynchronous AN responses to high-level energy ≤ 2 kHz. This is the first time CAP origins have been identified by a spatially specific technique. Our results show the need for revising the interpretation of the cochlear origins of high-level CAPs-ABR wave 1. NEW & NOTEWORTHY Cochlear compound action potentials (CAPs) and auditory brain stem responses (ABRs) are routinely used in laboratories and clinics. They are typically interpreted as arising from the cochlear region tuned to the stimulus frequency. However, as sound level is increased, the cochlear origins of CAPs from tone bursts of all frequencies become very wide and their centers shift toward the most sensitive cochlear region. The standard interpretation of CAPs and ABRs from moderate to intense stimuli needs revision.

Release and Recycling of the Readily Releasable Vesicle Population in a Synapse Possessing No Reserve Population

2007 ◽  
Vol 97 (6) ◽  
pp. 4048-4057 ◽  
Author(s):  
J. H. Koenig ◽  
Kazuo Ikeda
Keyword(s):  
High Frequency ◽  
Active Zone ◽  
Neuromuscular Junctions ◽  
Recycling Rate ◽  
Spontaneous Release ◽  
Electron Microscopic ◽  
Single Action ◽  
Active Zones ◽  
Evoked Activity ◽  
Microscopic Techniques

We previously demonstrated that the tergotrochanteral muscle (TTM) of Drosophila is innervated by unique synapses that possess a small readily releasable/recycling vesicle population (active zone population), but not the larger reserve vesicle population observed at other neuromuscular junctions in this animal. Using light and electron microscopic techniques and intracellular recording from the G1 muscle fiber of the TTM, the release and recycling characteristics of the readily releasable/recycling population were observed without any possible contribution from a reserve population. Our results indicate 1) the total number of vesicles in synapses presynaptic to the G1 fiber correlates with the total number of quanta that can be released onto this fiber; 2) the number of quanta released by a single action potential onto the G1 fiber is about one half the number of morphologically “docked” vesicles in active zones onto the G1, and this ratio decreases in a partially depleted state; 3) the recycling rate at 1-Hz stimulation, a frequency that does not cause any depression, is 0.24 recycled vesicle/active zone/s; and 4) normal-appearing spontaneous release occurs from the active zone vesicle population and, unlike synapses that possess a reserve population, the frequency of this release is reduced after high-frequency evoked activity.

Sensory processing in a thermal afferent pathway

1985 ◽  
Vol 53 (2) ◽  
pp. 429-434 ◽  
Author(s):  
S. N. Davies ◽  
G. E. Goldsmith ◽  
R. F. Hellon ◽  
D. Mitchell
Keyword(s):  
Sensory Processing ◽  
Receptive Fields ◽  
Second Order ◽  
Dynamic Responses ◽  
Trigeminal Nucleus ◽  
Afferent Pathway ◽  
Afferent Fibers ◽  
Level Of Activity ◽  
Caudal Trigeminal Nucleus ◽  
High Level

Extracellular recordings were made from cold-receptive afferent fibers in the trigeminal ganglion of rats anesthetized with halothane. By applying a standardized series of steady or changing temperatures to the receptive fields, we recorded the static and dynamic responses of the afferents. Comparable recordings were made from neurons in the marginal layer of the caudal trigeminal nucleus onto which the cold fibers synapse. The static and dynamic responses of the afferent fibers were reproduced faithfully by the second-order neurons, but at a much higher level of activity. Ganglionectomy silenced the second-order cells. Their continuous high level of activity appears to depend on the tonic input from the afferent fibers and not on any intrinsic circuits in the medulla.

scholarly journals Inactivation of KsgA, a 16S rRNA Methyltransferase, Causes Vigorous Emergence of Mutants with High-Level Kasugamycin Resistance

2008 ◽  
Vol 53 (1) ◽  
pp. 193-201 ◽  
Author(s):  
Kozo Ochi ◽  
Ji-Yun Kim ◽  
Yukinori Tanaka ◽  
Guojun Wang ◽  
Kenta Masuda ◽  
...  
Keyword(s):  
16S Rrna ◽  
High Frequency ◽  
Resistance Mutations ◽  
Gene Encoding ◽  
Adenosylmethionine Decarboxylase ◽  
Ribosomal Function ◽  
High Level ◽  
Antibiotic Resistance Mutations ◽  
Modest Level ◽  
Level Resistance

ABSTRACT The methyltransferases RsmG and KsgA methylate the nucleotides G535 (RsmG) and A1518 and A1519 (KsgA) in 16S rRNA, and inactivation of the proteins by introducing mutations results in acquisition of low-level resistance to streptomycin and kasugamycin, respectively. In a Bacillus subtilis strain harboring a single rrn operon (rrnO), we found that spontaneous ksgA mutations conferring a modest level of resistance to kasugamycin occur at a high frequency of 10−6. More importantly, we also found that once cells acquire the ksgA mutations, they produce high-level kasugamycin resistance at an extraordinarily high frequency (100-fold greater frequency than that observed in the ksgA + strain), a phenomenon previously reported for rsmG mutants. This was not the case for other antibiotic resistance mutations (Tspr and Rifr), indicating that the high frequency of emergence of a mutation for high-level kasugamycin resistance in the genetic background of ksgA is not due simply to increased persistence of the ksgA strain. Comparative genome sequencing showed that a mutation in the speD gene encoding S-adenosylmethionine decarboxylase is responsible for the observed high-level kasugamycin resistance. ksgA speD double mutants showed a markedly reduced level of intracellular spermidine, underlying the mechanism of high-level resistance. A growth competition assay indicated that, unlike rsmG mutation, the ksgA mutation is disadvantageous for overall growth fitness. This study clarified the similarities and differences between ksgA mutation and rsmG mutation, both of which share a common characteristic—failure to methylate the bases of 16S rRNA. Coexistence of the ksgA mutation and the rsmG mutation allowed cell viability. We propose that the ksgA mutation, together with the rsmG mutation, may provide a novel clue to uncover a still-unknown mechanism of mutation and ribosomal function.

Synaptic Activation of Dendritic AMPA and NMDA Receptors Generates Transient High-Frequency Firing in Substantia Nigra Dopamine Neurons In Vitro

2007 ◽  
Vol 97 (4) ◽  
pp. 2837-2850 ◽  
Author(s):  
Sarah N. Blythe ◽  
Jeremy F. Atherton ◽  
Mark D. Bevan
Keyword(s):  
Nmda Receptor ◽  
Substantia Nigra ◽  
Action Potential ◽  
Nmda Receptors ◽  
High Frequency ◽  
Brain Slices ◽  
Dopamine Neurons ◽  
Frequency Pattern ◽  
High Frequency Activity ◽  
Evoked Activity

Transient high-frequency activity of substantia nigra dopamine neurons is critical for striatal synaptic plasticity and associative learning. However, the mechanisms underlying this mode of activity are poorly understood because, in contrast to other rapidly firing neurons, high-frequency activity is not evoked by somatic current injection. Previous studies have suggested that activation of dendritic N-methyl-d-aspartate (NMDA) receptors and/or G-protein-coupled receptor (GPCR)-mediated reduction of action potential afterhyperpolarization and/or activation of cation channels underlie high-frequency activity. To address their relative contribution, transient high-frequency activity was evoked using local electrical stimulation (1 s, 10–100 Hz) in brain slices prepared from p15–p25 rats in the presence of GABA and D2 dopamine receptor antagonists. The frequency, pattern, and morphology of action potentials evoked under these conditions were similar to those observed in vivo. Evoked activity and reductions in action potential afterhyperpolarization were diminished greatly by application of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) or NMDA receptor selective antagonists and abolished completely by co-application of AMPA and NMDA antagonists. In contrast, application of glutamatergic and cholinergic GPCR antagonists moderately enhanced evoked activity. Dendritic pressure-pulse application of glutamate evoked high-frequency activity that was similarly sensitive to antagonism of AMPA or NMDA receptors. Taken together, these data suggest that dendritic AMPA and NMDA receptor-mediated synaptic conductances are sufficient to generate transient high-frequency activity in substantia nigra dopamine neurons by rapidly but transiently overwhelming the conductances underlying action potential afterhyperpolarization and/or engaging postsynaptic voltage-dependent ion channels in a manner that overcomes the limiting effects of afterhyperpolarization.

Clinical and neurophysiological peculiarities of tumor-related epilepsy

2020 ◽  
Vol 20 (2) ◽  
pp. 87-96
Author(s):  
Nadezhda V. Tolstykh ◽  
Alexander F. Gurchin ◽  
Nadezhda Yu. Koroleva ◽  
Igor D. Stolyarov
Keyword(s):  
High Frequency ◽  
Epileptiform Activity ◽  
Neurophysiological Monitoring ◽  
Tumor Control ◽  
Positron Emission ◽  
Symptomatic Epilepsy ◽  
Structural Epilepsy ◽  
High Level ◽  
Video Eeg

Detection and correction of structural tumor-associated epilepsy remain relevant at the present time. Seizures occur in 7590% of cases in patients with gliomas of malignancys various degrees. The aim of this work was to clarify the links of pathogenesis and clinical and neurophysiological features of structural epilepsy in intracerebral tumors. Materials and methods. We examined 23 patients with intracerebral tumors and symptomatic epilepsy. Results. Epileptiform activity was registered in 2 or more regions in more than half of the patients 12 people (52.18%), and 7 of them (58.3%) it spread to neighboring leads. No association was found between the size of the tumor and the number of attacks. Conclusions. Grade III tumors predominate among patients with tumor-related epilepsy. In this population with a high frequency after surgery, both tumor control and freedom from seizures can be achieved. It is necessary to manage this group of patients after surgery with regular neurophysiological monitoring (MRI, positron-emission tomography and video-EEG monitoring) to correct antiepileptic therapy and maintain a high level of quality of life.

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