ANN-Based System for Sorting Spike Waveforms Employing Refractory Periods

2005 ◽  
pp. 121-126 ◽  
Author(s):  
Thomas Hermle ◽  
Martin Bogdan ◽  
Cornelius Schwarz ◽  
Wolfgang Rosenstiel
Keyword(s):  
Refractory Periods ◽  
Spike Waveforms

The Initiation and Conduction of Action Potentials in the Optic Nerve of Tritonia

1974 ◽  
Vol 60 (3) ◽  
pp. 721-734
Author(s):  
RONALD CHASE
Keyword(s):  
Optic Nerve ◽  
Action Potentials ◽  
Sensory Cells ◽  
Refractory Periods ◽  
Graded Responses ◽  
Trigger Zone ◽  
A Site ◽  
Spike Waveforms ◽  
Cerebral Nerve ◽  
Primary Sensory Cells

1. The optic nerve of Tritonia contains axons of the five primary sensory cells. It joins a cerebral nerve about 2.0 mm from the eye and then travels another 2.5 mm to the central ganglia. 2. Large DC responses of positive polarity were recorded with suction electrodes in the presence of light. These graded responses are generator potentials passively conducted from a site of origin in or near the receptor somata. DC responses to light were not recorded at points central to the junction of the optic nerve with the cerebral nerve. 3. The shape of extracellular spike waveforms and the temporal relationship between soma and nerve spikes support the conclusion that action potentials are initiated in the optic nerve. In the,dark, spikes originate in portions of the nerve distant from the eye. When the eye is illuminated, the trigger zone shifts about 700 µm more proximal to the eye. 4. The shift in the spike trigger zone during illumination probably reflects an habitual accommodation of proximal portions of the nerve under the conditions of these experiments, and the prevalence of partially or completely silent optic nerves is probably due to more severe consequences of sustained depolarization. The sensitivity of the receptors, in combination with the passive properties of the nerve, makes the nerve susceptible to debilitating effects of maintained illumination. 5. The excitability of optic nerve fibres is extremely low. Absolute refractory periods are 25 msec, and relative refractory periods are as long as several hundred msec. When stimulated with just-suprathreshold voltages the nerve cannot support action potentials at frequencies greater than 1 Hz. 6. The Tritonia optic nerve appears to be transitional between transmission by graded responses and transmission by action potentials.

scholarly journals Wireless logging of extracellular neuronal activity in the telencephalon of free-swimming salmonids

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Susumu Takahashi ◽  
Takumi Hombe ◽  
Riku Takahashi ◽  
Kaoru Ide ◽  
Shinichiro Okamoto ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Environmental Cues ◽  
Fish Movement ◽  
Water Tank ◽  
Head Direction ◽  
Free Swimming ◽  
Rodent Brain ◽  
River Migration ◽  
Spike Waveforms ◽  
The Brain

Abstract Background Salmonids return to the river where they were born in a phenomenon known as mother-river migration. The underpinning of migration has been extensively examined, particularly regarding the behavioral correlations of external environmental cues such as the scent of the mother-river and geomagnetic compass. However, neuronal underpinning remains elusive, as there have been no biologging techniques suited to monitor neuronal activity in the brain of large free-swimming fish. In this study, we developed a wireless biologging system to record extracellular neuronal activity in the brains of free-swimming salmonids. Results Using this system, we recorded multiple neuronal activities from the telencephalon of trout swimming in a rectangular water tank. As proof of principle, we examined the activity statistics for extracellular spike waveforms and timing. We found cells firing maximally in response to a specific head direction, similar to the head direction cells found in the rodent brain. The results of our study suggest that the recorded signals originate from neurons. Conclusions We anticipate that our biologging system will facilitate a more detailed investigation into the neural underpinning of fish movement using internally generated information, including responses to external cues.

scholarly journals His-Purkinje responses and refractory periods during atrial extrastimulation in children with heart defects.

Circulation ◽  
1981 ◽  
Vol 63 (6) ◽  
pp. 1383-1390 ◽  
Author(s):  
G S Wolff ◽  
A Mehta ◽  
D Tamer ◽  
O L Garcia ◽  
A S Pickoff ◽  
...  
Keyword(s):  
Heart Defects ◽  
Refractory Periods

The Electrical Activity of the Radial Nerve in Diadema antillarum Philippi and Certain Other Echinoids

1968 ◽  
Vol 48 (2) ◽  
pp. 279-289
Author(s):  
N. MILLOTT ◽  
H. OKUMURA
Keyword(s):  
Electrical Activity ◽  
Conduction Velocity ◽  
Radial Nerve ◽  
Diadema Antillarum ◽  
Double Peak ◽  
Slow Potential ◽  
Refractory Periods ◽  
Spine Movement ◽  
Stimulation Of

1. The propagated massed potentials which follow stimulation of the radial nerve in Arbacia, Diadema, Echinus and Paracentrotus are described. 2. Approximate values for the averaged absolute and relative refractory periods and the conduction velocity were obtained. 3. The response of Diadema has a double peak which is shown to represent responses of nerves differing in excitability and conduction velocity. The fast potential is concerned with spine movement. The slow potential is related to inhibition of spine movements excited photically.

Mormyromast electroreceptor organs and their afferent fibers in mormyrid fish. II. Intra-axonal recordings show initial stages of central processing

1990 ◽  
Vol 63 (2) ◽  
pp. 303-318 ◽  
Author(s):  
C. C. Bell
Keyword(s):  
Lateral Line ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Direct Stimulation ◽  
Postsynaptic Potentials ◽  
Central Processing ◽  
Refractory Periods ◽  
Synaptic Potentials ◽  
Afferent Fibers ◽  
Stimulation Of

1. Physiologically and morphologically identified primary afferent fibers from mormyromast electroreceptor organs were recorded intracellularly. The fiber recordings were made from the nerve root of the posterior lateral line nerve, where the fibers enter the brain, and from the electrosensory lateral line lobe (ELL), near the central terminals of the fibers. 2. The intracellular recordings reveal a variety of potentials, synaptic and nonsynaptic, in addition to the large orthodromic action potentials from the periphery. The goal of the present study was to describe and interpret these various potentials in mormyromast afferent fibers as a first step in understanding the processing of electrosensory information in ELL. 3. Three types of synaptic potentials were recorded inside mormyromast afferent fibers: 1) electric organ corollary discharge (EOCD) excitatory postsynaptic potentials (EPSPs), driven by the motor command that elicits the electric organ discharge (EOD); 2) EPSPs evoked by electrosensory stimulation of electroreceptors in the skin near the electroreceptor from which the recorded fiber originates or by direct stimulation of an electrosensory nerve; and 3) inhibitory postsynaptic potentials (IPSPs) evoked by electrosensory stimulation of more distant electroreceptors. These synaptic potentials can be attributed to synaptic input to postsynaptic cells in ELL that is observed inside the afferent fibers because of electrical synapses between the fibers and the postsynaptic cells. 4. The peripherally evoked EPSPs could frequently be shown to be unitary. The unitary EPSPs were identical to the orthodromic spikes in originating from a single electroreceptor, in threshold, and in latency shift with increasing stimulus intensity. These similarities suggest that the unitary EPSPs are electrotonic EPSPs caused by impulses in other mormyromast afferent fibers that terminate on some of the same postsynaptic cells as the recorded fiber. The peripherally evoked IPSPs had a longer latency than the EPSPs or orthodromic spikes, requiring the presence of an inhibitory interneuron. 5. The peripherally evoked EPSPs, both unitary and nonunitary, show absolute refractory periods of 3-8 ms, followed by relative refractory periods of approximately 8 ms, when tested with two identical stimuli to a nerve. These refractory periods are interpreted as because of refractoriness in the fine preterminal branches of the axonal arbor. 6. A depolarizing afterpotential is commonly associated with the orthodromic spike and probably results from the successful propagation of the spike into the entire terminal arbor. The depolarizing afterpotential has a refractory period that is similar to that of the peripherally evoked EPSPs and that is also interpreted as refractoriness in the fine preterminal branches.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Spike sorting with Gaussian mixture models

2018 ◽  
Author(s):  
Bryan C. Souza ◽  
Vítor Lopes-dos-Santos ◽  
João Bacelo ◽  
Adriano B. L. Tort
Keyword(s):  
Mixture Models ◽  
Principal Components ◽  
Gaussian Mixture Models ◽  
Gaussian Mixture ◽  
Spike Sorting ◽  
Main Challenge ◽  
Manual Adjustment ◽  
Cluster Properties ◽  
Spike Waveforms ◽  
Friendly Graphical User Interface

AbstractThe shape of extracellularly recorded action potentials is a product of several variables, such as the biophysical and anatomical properties of the neuron and the relative position of the electrode. This allows for isolating spikes of different neurons recorded in the same channel into clusters based on waveform features. However, correctly classifying spike waveforms into their underlying neuronal sources remains a main challenge. This process, called spike sorting, typically consists of two steps: (1) extracting relevant waveform features (e.g., height, width), and (2) clustering them into non-overlapping groups believed to correspond to different neurons. In this study, we explored the performance of Gaussian mixture models (GMMs) in these two steps. We extracted relevant waveform features using a combination of common techniques (e.g., principal components and wavelets) and GMM fitting parameters (e.g., standard deviations and peak distances). Then, we developed an approach to perform unsupervised clustering using GMMs, which estimates cluster properties in a data-driven way. Our results show that the proposed GMM-based framework outperforms previously established methods when using realistic simulations of extracellular spikes and actual extracellular recordings to evaluate sorting performance. We also discuss potentially better techniques for feature extraction than the widely used principal components. Finally, we provide a friendly graphical user interface in MATLAB to run our algorithm, which allows for manual adjustment of the automatic results.

scholarly journals Epithelial Conduction in Hydromedusae

1968 ◽  
Vol 52 (3) ◽  
pp. 600-621 ◽  
Author(s):  
G. O. Mackie ◽  
L. M. Passano
Keyword(s):  
Nervous System ◽  
Spontaneous Activity ◽  
Nervous Activity ◽  
The Other ◽  
Refractory Periods ◽  
Spread Of Excitation ◽  
Composite Events ◽  
Waves Propagation ◽  
Excess Mg ◽  
Electrical Stimuli

Sarsia, Euphysa, and other hydromedusae have been studied by electrophysiological techniques and are found to have nonnervous conducting epithelia resembling those described earlier for siphonophores. Simple, nonmuscular epithelia fire singly or repetitively following brief electrical stimuli. The pulses recorded with suction electrodes are biphasic, initially positive, and show amplitudes of 0.75–2.0 mv, durations of 5–15 msec, and velocities of 15–35 cm/sec with short refractory periods. In the swimming muscle (myoepithelium) 2.0–4.0 mv composite events lasting 150–300 msec are associated with contraction waves. Propagation in nonnervous epithelia is typically all-or-none, nondecremental, and unpolarized. The subumbrellar endoderm lamella conducts independently of the adjacent ectoderm. The lower regions of the tentacles do not show propagated epithelial events. The spread of excitation in conducting epithelia and associated effector responses are described. Examples are given of interaction between events seemingly conducted in the nervous system and those in nonnervous epithelia. Either system may excite the other. Spontaneous activity, however, appears to originate in the nervous system. Conduction in nonnervous tissues is unaffected by excess Mg++ in concentrations suppressing presumed nervous activity, although this may not be a wholly adequate criterion for distinguishing components of the two systems. Evidence from old work by Romanes is considered in the light of these findings and the general significance of epithelial conduction is discussed.

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