scholarly journals Types of unitary response and correlation with the field potential profile during activation of the avian optic tectum

1968 ◽  
Vol 194 (1) ◽  
pp. 91-104 ◽  
Author(s):  
A. L. Holden
Keyword(s):  
Optic Tectum ◽  
Field Potential ◽  
Potential Profile ◽  
Unitary Response

Mechanism for Increased Hippocampal Synaptic Strength Following Differential Experience

2001 ◽  
Vol 85 (4) ◽  
pp. 1377-1383 ◽  
Author(s):  
T. C. Foster ◽  
T. C. Dumas
Keyword(s):  
Synaptic Transmission ◽  
Hippocampal Slices ◽  
Field Potential ◽  
Synaptic Strength ◽  
Synaptic Response ◽  
Paired Pulse ◽  
Unitary Response ◽  
The Mean ◽  
Novel Environments ◽  
Differential Experience

Exposure to novel environments or behavioral training is associated with increased strength at hippocampal synapses. The present study employed quantal analysis techniques to examine the mechanism supporting changes in synaptic transmission that occur following differential behavioral experience. Measures of CA1 synaptic strength were obtained from hippocampal slices of rats exposed to novel environments or maintained in individual cages. The input/output (I/O) curve of extracellularly recorded population excitatory postsynaptic potentials (EPSPs) increased for animals exposed to enrichment. The amplitude of the synaptic response of the field potential was related to the fiber potential amplitude and the paired-pulse ratio, however, these measures were not altered by differential experience. Estimates of biophysical parameters of transmission were determined for intracellularly recorded unitary responses of CA1 pyramidal cells. Enrichment was associated with an increase in the mean unitary synaptic response, an increase in quantal size, and a trend for decreased input resistance and reduction in the stimulation threshold to elicit a unitary response. Paired-pulse facilitation, the percent of response failures, coefficient of variance, and estimates of quantal content were not altered by experience but correlated well with the mean unitary response amplitude. The results suggest that baseline synaptic strength is determined, to a large extent, by presynaptic release mechanisms. However, increased synaptic transmission following environmental enrichment is likely due to an increase in the number or efficacy of receptors at some synapses and the emergence of functional synaptic contacts between previously unconnected CA3 and CA1 cells.

scholarly journals Space coding by gamma oscillations in the barn owl optic tectum

2011 ◽  
Vol 105 (5) ◽  
pp. 2005-2017 ◽  
Author(s):  
Devarajan Sridharan ◽  
Kwabena Boahen ◽  
Eric I. Knudsen
Keyword(s):  
Optic Tectum ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Stimulus Location ◽  
Gamma Band ◽  
Sensory Stimuli ◽  
Visual Contrast ◽  
Wide Range ◽  
Gamma Power ◽  
Deep Layers

Gamma-band (25–140 Hz) oscillations of the local field potential (LFP) are evoked by sensory stimuli in the mammalian forebrain and may be strongly modulated in amplitude when animals attend to these stimuli. The optic tectum (OT) is a midbrain structure known to contribute to multimodal sensory processing, gaze control, and attention. We found that presentation of spatially localized stimuli, either visual or auditory, evoked robust gamma oscillations with distinctive properties in the superficial (visual) layers and in the deep (multimodal) layers of the owl's OT. Across layers, gamma power was tuned sharply for stimulus location and represented space topographically. In the superficial layers, induced LFP power peaked strongly in the low-gamma band (25–90 Hz) and increased gradually with visual contrast across a wide range of contrasts. Spikes recorded in these layers included presumptive axonal (input) spikes that encoded stimulus properties nearly identically with gamma oscillations and were tightly phase locked with the oscillations, suggesting that they contribute to the LFP oscillations. In the deep layers, induced LFP power was distributed across the low and high (90–140 Hz) gamma-bands and tended to reach its maximum value at relatively low visual contrasts. In these layers, gamma power was more sharply tuned for stimulus location, on average, than were somatic spike rates, and somatic spikes synchronized with gamma oscillations. Such gamma synchronized discharges of deep-layer neurons could provide a high-resolution temporal code for signaling the location of salient sensory stimuli.

Natural image reconstruction on the basis of local field potential signals of pigeon optic tectum neurons

Neuroreport ◽  
2018 ◽  
Vol 29 (13) ◽  
pp. 1092-1098 ◽  
Author(s):  
Zhizhong Wang ◽  
Xingyang Jiao ◽  
Songwei Wang ◽  
Xiaoke Niu ◽  
Li Shi
Keyword(s):  
Image Reconstruction ◽  
Local Field ◽  
Optic Tectum ◽  
Local Field Potential ◽  
Field Potential ◽  
Natural Image

Ongoing activity in the optic tectum is correlated on a trial-by-trial basis with the pupil dilation response

2014 ◽  
Vol 111 (5) ◽  
pp. 918-929 ◽  
Author(s):  
Shai Netser ◽  
Arkadeb Dutta ◽  
Yoram Gutfreund
Keyword(s):  
Neural Activity ◽  
Optic Tectum ◽  
Internal State ◽  
Field Potential ◽  
Behavioral Responses ◽  
Orienting Response ◽  
Pupil Dilation ◽  
Ongoing Activity ◽  
Potential Oscillations ◽  
Deep Layers

The selection of the appropriate stimulus to induce an orienting response is a basic task thought to be partly achieved by tectal circuitry. Here we addressed the relationship between neural activity in the optic tectum (OT) and orienting behavioral responses. We recorded multiunit activity in the intermediate/deep layers of the OT of the barn owl simultaneously with pupil dilation responses (PDR, a well-known orienting response common to birds and mammals). A trial-by-trial analysis of the responses revealed that the PDR generally did not correlate with the evoked neural responses but significantly correlated with the rate of ongoing neural activity measured shortly before the stimulus. Following this finding, we characterized ongoing activity in the OT and showed that in the intermediate/deep layers it tended to fluctuate spontaneously. It is characterized by short periods of high ongoing activity during which the probability of a PDR to an auditory stimulus inside the receptive field is increased. These high-ongoing activity periods were correlated with increase in the power of gamma band local field potential oscillations. Through dual recordings, we showed that the correlation coefficients of ongoing activity decreased as a function of distance between recording sites in the tectal map. Significant correlations were also found between recording sites in the OT and the forebrain entopallium. Our results suggest that an increase of ongoing activity in the OT reflects an internal state during which coupling between sensory stimulation and behavioral responses increases.

Luminance information decoding on the basis of local field potential signals of pigeon optic tectum neurons

Neuroreport ◽  
2017 ◽  
Vol 28 (16) ◽  
pp. 1036-1042 ◽  
Author(s):  
Songwei Wang ◽  
Lijun Liu ◽  
Zhizhong Wang ◽  
Xiaoke Niu ◽  
Yuxia Hu ◽  
...  
Keyword(s):  
Local Field ◽  
Optic Tectum ◽  
Local Field Potential ◽  
Field Potential

Presynaptic calcium dynamics at the frog retinotectal synapse

1996 ◽  
Vol 76 (1) ◽  
pp. 381-400 ◽  
Author(s):  
M. B. Feller ◽  
K. R. Delaney ◽  
D. W. Tank
Keyword(s):  
Optic Nerve ◽  
Action Potential ◽  
Optic Tectum ◽  
Field Potential ◽  
Nerve Fibers ◽  
Saturation Effect ◽  
Tetraacetic Acid ◽  
Field Potentials ◽  
Fura 2 ◽  
Fluorescence Transients

1. We characterized the kinetics of presynaptic Ca2+ ion concentration in optic nerve fibers and terminals of the optic tectum in Rana pipiens with the use of microfluorimetry. Isolated frog brains were incubated with the membrane-permeant tetraacetoxymethyl ester (AM) of the Ca2+ indicator fura-2. An optic nerve shock caused a transient decrease in the 380-nm excited fluorescence in the optic tectum with a rise time of <15 ms and a recovery to prestimulus levels on a time scale of seconds. 2. In normal saline, the amplitude of the fluorescence transients was dependent on stimulus intensity and at all levels it was directly correlated with the amplitude of postsynaptic field potentials produced by activation of unmyelinated optic nerve fibers. In the presence of the non-N-methyl-D-aspartate glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione, the amplitude and time course of fluorescence transients remained essentially unchanged while postsynaptic field potential amplitude was greatly reduced. Replacing extracellular Ca2+ with Ba2+ blocked unfacilitated postsynaptic field potentials while fluorescence transients remained significant. In reduced-Ca2+ salines (<1 mM), the amplitude of fluorescence transients increased approximately linearly with extracellular [Ca2+], whereas the amplitude the corresponding field potential was nonlinearly related to the fluorescent transient amplitude (approximately 2.5 power). In thin sections of labeled tecta, fluorescence labeling was localized to 1-micron puncta in the termination zone of optic nerve fibers in the superficial layers. Taken together, these results provide strong evidence that the fluorescence transients correspond to an increase in Ca2+ in presynaptic terminals of unmyelinated optic nerve fibers. 3. During trains of optic nerve stimulation, the amplitude of fluorescence transients to succeeding action potentials became smaller. The decrement of the amplitudes was not observed in mag-fura-5-labeled tecta, when the intracellular Ca2+ buffering capacity of fura-2-labeled terminals was increased by incubation with bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid (BAPTA)-AM or ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)-AM, or in low-Ca2+ saline. We conclude that the Ca2+ influx per action potential is constant during the train and that the reduced response was produced by saturation of the fura-2. We provide a mathematical analysis of this saturation effect and use it to estimate the Ca2+ change per action potential. 4. Both BAPTA-AM and EGTA-AM reduced the overall amplitude of fura-2-measured Ca2+ transients and reduced the saturation effect in action potential trains. However, there was a qualitative difference in their effects on the shape of the transient. Incubation with the fast buffer BAPTA prolonged the decay to baseline. In contrast, the slow buffer EGTA (or EDTA) produced an initial decay faster than the control condition while also producing the slower subsequent phase observed with BAPTA. We demonstrate that these results are consistent with numerical simulations of Ca2+ dynamics in a single-compartment model where the fast initial decay is produced by the forward rate of Ca2+ binding to EGTA. 5. Ca2+ influx into tectal presynaptic structures, and also into unmyelinated axons in the isolated optic nerve, was diminished (60-70%) in the presence of the voltage-activated Ca2+ channel blocker omega-conotoxin GVIA, but was only weakly affected (approximately 10%) by omega-agatoxin IVA. 6. After 10- to 50-Hz stimulus trains, synaptic enhancement of unmyelinated fibers decayed with a characteristic time similar to fura-2 fluorescence decays. Incubation with EDTA-AM or EGTA-AM produced little effect on evoked release but reduced both the amplitude of the fura-2-measured Ca2+ transient and the amplitude of short-term synaptic enhancement.

scholarly journals Evolution of Epileptiform Activity in Zebrafish by Statistical-Based Integration of Electrophysiology and 2-Photon Ca2+ Imaging

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 769 ◽  
Author(s):  
Olga Cozzolino ◽  
Federico Sicca ◽  
Emanuele Paoli ◽  
Francesco Trovato ◽  
Filippo M. Santorelli ◽  
...  
Keyword(s):  
Optic Tectum ◽  
Epileptiform Activity ◽  
Field Potential ◽  
Imaging Data ◽  
Spatiotemporal Evolution ◽  
Neuronal Populations ◽  
Anti Epileptic Drug ◽  
Vertebrate Model ◽  
Epilepsy Models ◽  
Local Field Potential Lfp

The study of sources and spatiotemporal evolution of ictal bursts is critical for the mechanistic understanding of epilepsy and for the validation of anti-epileptic drugs. Zebrafish is a powerful vertebrate model representing an excellent compromise between system complexity and experimental accessibility. We performed the quantitative evaluation of the spatial recruitment of neuronal populations during physiological and pathological activity by combining local field potential (LFP) recordings with simultaneous 2-photon Ca2+ imaging. We developed a method to extract and quantify electrophysiological transients coupled with Ca2+ events and we applied this tool to analyze two different epilepsy models and to assess the efficacy of the anti-epileptic drug valproate. Finally, by cross correlating the imaging data with the LFP, we demonstrated that the cerebellum is the main source of epileptiform transients. We have also shown that each transient was preceded by the activation of a sparse subset of neurons mostly located in the optic tectum.

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