Electrical Activity and Structure of Retinal Cells of the Aplysia Eye: I. Secondary Neurones

1982 ◽  
Vol 99 (1) ◽  
pp. 369-380
Author(s):  
JON W. JACKLET ◽  
LESLEY SCHUSTER ◽  
CELINE ROLERSON
Keyword(s):  
Optic Nerve ◽  
Electrical Activity ◽  
Action Potentials ◽  
Lucifer Yellow ◽  
Antidromic Activation ◽  
Retinal Cells ◽  
Compound Action Potentials ◽  
Pacemaker Potentials ◽  
Evoked Activity ◽  
Chemical Synapses

1. Intracellular recordings were made from secondary neurones and photo-receptors of the Aplysia eye concurrently with extracellular recordings from the optic nerve. These cells were injected with Lucifer yellow to reveal their structure after they were typed according to electrical activity. Secondary neurones are described in this paper. 2. All secondary neurones injected with Lucifer yellow were in the outer, non-receptor layer of the retina. Each had an axon in the optic nerve, short dendritic processes on the soma, but no distinct photoreceptive apparatus. Dye coupling between secondary neurones and between secondary neurones and photoreceptors was observed. 3. Secondary neurones had pacemaker potentials and action potentials (APs) correlated 1:1 with the optic nerve compound action potentials (CAPs) during spontaneous dark and light evoked activity. It is deduced that the secondary neurones are the output neurones of the circadian clock system of the eye. 4. Secondary neurones appear to be electrically coupled to each other and to some photoreceptors, since blocking chemical synapses with high Mg2+ saline did not block the spontaneous or light evoked activities, and antidromic activation of the secondary neurones produced a compound input dependent in amplitude on stimulus voltage. 5. Backfilling the optic nerve with cobalt revealed filled secondary neurones, 2 photoreceptor types and a small non-receptor cell type suggesting that most of these retinal cells have axons in the optic nerve.

Electrical Activity and Structure of Retinal Cells of the Aplysia Eye: II. Photoreceptors

1982 ◽  
Vol 99 (1) ◽  
pp. 381-395
Author(s):  
JON W. JACKLET ◽  
CELINE ROLERSON
Keyword(s):  
Electron Microscope ◽  
Optic Nerve ◽  
Action Potentials ◽  
Light Adaptation ◽  
Lucifer Yellow ◽  
Electrical Coupling ◽  
Light Response ◽  
Dye Coupling ◽  
Compound Action Potentials ◽  
Compound Action

1. Photoreceptors of the eye of Aplysia were studied by intracellular recording and Lucifer yellow injection. 2. Two basic photoreceptor types were observed, R and H. Two other types of cells were occasionally encountered: one was neurone-like, giving only a slight depolarization but large action potentials (APs) in response to light; the other was presumably glial. 3. Type R photoreceptors were found in the pigmented layer of the retina, had large distal (photoreceptor) processes extending toward the lens and an axon in the optic nerve. They are probably the large, microvillous receptor type with vesicle-filled cytoplasm observed previously in electron microscope studies. Action potentials were observed in the axon but not the cell body of the R receptor. The light response was an increasing conductance, 2 component depolarization followed by hyperpolarization. All 3 components were affected by light adaptation. Electrical coupling between R receptors and secondary neurones was apparent and the system produces the synchronous compound action potentials (CAPs) in the optic nerve. 4. Type H photoreceptors gave a slight depolarization to light with APs, followed by a hyperpolarization, followed by a late depolarization and more APs. They were in the pigmented layer of the retina and had smaller cell bodies and distal processes, but larger axons than R receptors. They may correspond to the photoreceptors with short microvilli and occasional cilia described previously in electron microscope studies. Electrical and dye coupling occurred between the receptors. The H receptors do not contribute to the CAP, but produce separate unitary potentials in the optic nerve.

Factors determining the frequency content of the electromyogram

1983 ◽  
Vol 55 (2) ◽  
pp. 392-399 ◽  
Author(s):  
H. Kranz ◽  
A. M. Williams ◽  
J. Cassell ◽  
D. J. Caddy ◽  
R. B. Silberstein
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Nerve Fibers ◽  
Frequency Content ◽  
Muscle Properties ◽  
Spectral Content ◽  
Unit Discharge ◽  
Compound Action Potentials ◽  
Motor Unit Discharge ◽  
Compound Action

The contribution of central and peripheral factors to the frequency content of the electromyogram was examined in 10 subjects performing maximal 45-s contractions of thenar muscles. The median frequencies (Fm) of surface-recorded electromyograms and compound action potentials were similar early (P greater than 0.6) and late (P greater than 0.5) in the contractions. There was a mean decrease in the Fm during contraction of 39% for electromyograms and 35% for compound potentials (P greater than 0.1). The Fm of electromyograms increased 11% (P less than 0.02) in only the 1st s of contraction as force was raised from 25 to 100% of maximum. Only one of five subjects showed evidence of increasing synchronization of motor unit discharge during contraction. There was no evidence that delay or dispersion of action potential propagation in terminal nerve fibers or at the neuromuscular junction had a significant effect on frequency content. The findings indicated that the spectral content of muscle electrical activity, and its shift during contraction, primarily reflects intrinsic muscle properties.

Reflexes, fictive respiration and cell division in the brain and spinal cord of the newborn opossum, Monodelphis domestica, isolated and maintained in vitro

1990 ◽  
Vol 152 (1) ◽  
pp. 1-15
Author(s):  
J. G. Nicholls ◽  
R. R. Stewart ◽  
S. D. Erulkar ◽  
N. R. Saunders
Keyword(s):  
Spinal Cord ◽  
Electrical Activity ◽  
Action Potentials ◽  
Monodelphis Domestica ◽  
Spinal Reflexes ◽  
Bathing Solution ◽  
Proliferative Zone ◽  
Compound Action Potentials ◽  
Compound Action

1. The entire central nervous system (CNS) was isolated from 1- to 4-day-old newborn South American opossums (Monodelphis domestica). At this stage the CNS has only an embryonic forebrain (two-layered) and no cerebellum and corresponds to a 14-day rat embryo. Its eyes, ears and hind-limbs are only at an early stage of formation. The isolated CNS preparations continue to develop and to produce electrical signals for up to 4 days in oxygenated Krebs' fluid at 23 degrees C. 2. The longitudinal axis of the CNS showed markedly different stages of development. More neuroblast cells were present in the proliferative zone in lumbosacral than in cervical or thoracic regions of the cord. 3. The progeny of dividing cells were labelled in isolated preparations by applying bromodeoxyuridine (BrdU) to the bathing solution for 2 h. Stained precursor cells were observed in CNS that had been left in Krebs' fluid for 4 days before applying BrdU and also in CNS that had been exposed to BrdU shortly after dissection and then left for 4 days. 4. Compound action potentials were evoked from the isolated CNS by stimulation with extracellular electrodes. Compound action potentials increased in amplitude with stronger stimulation and showed discrete peaks of conduction velocity. All electrical activity was eliminated reversibly by 0.1 mumol l-1 tetrodotoxin applied to the bathing solution. Block and recovery occurred with a half-time of approximately 5 min. High concentrations of magnesium (20 mmol l-1) reversibly blocked slower components of the volley. 5. Reflexes in cervical and thoracic segments of the spinal cord continued to function in isolated preparations. Stimulation of a dorsal root evoked bursts of impulses in the appropriate ventral root. Spontaneous and evoked activity in ventral roots was eliminated reversibly by 20 mmol l-1 magnesium. 6. In thoracic segments, spontaneous rhythmical bursts of action potentials were recorded. Burst activity was correlated with respiratory movements of the ribs in semi-intact preparations in which a few ribs and muscles were left attached to the isolated CNS. 7. At raised temperatures of 28 degrees C compared to 23 degrees C both spontaneous and evoked electrical activity were reversibly reduced. 8. Together these results show that the isolated CNS of the newborn opossum survives well in culture. The preparation offers advantages for pharmacological and physiological studies of spinal reflexes, for analysis of the mechanisms underlying rhythmical respiratory activity and for following the time course of CNS development in vitro.

Changes of compound action potentials in retrograde axonal degeneration of rat optic nerve

1995 ◽  
Vol 132 (2) ◽  
pp. 262-270 ◽  
Author(s):  
Miho Sugioka ◽  
Hajime Sawai ◽  
Eijiro Adachi ◽  
Yutaka Fukuda
Keyword(s):  
Optic Nerve ◽  
Action Potentials ◽  
Axonal Degeneration ◽  
Compound Action Potentials ◽  
Compound Action

Excitation and inhibition of the heart of the snail, Lymnaea, by non-FMRFamidergic motoneurons

1990 ◽  
Vol 63 (6) ◽  
pp. 1436-1447 ◽  
Author(s):  
K. J. Buckett ◽  
M. Peters ◽  
P. R. Benjamin
Keyword(s):  
Heart Muscle ◽  
Action Potentials ◽  
Lucifer Yellow ◽  
Constant Delay ◽  
Intracellular Injection ◽  
Neuronal Control ◽  
Fourth Class ◽  
Selective Antagonists ◽  
Chemical Synapses ◽  
Alpha Bungarotoxin

1. The present paper extends the model of neuronal control of the Lymnaea heart by the use of intracellular recording techniques to identify further types of cardioactive neurons in the CNS that, like the previously described E heart excitor (Ehe) cells, influence the myogenic heartbeat. 2. Four new types of neuron that act on the heart are described. These are excitatory Hhe and She cells (H and S heart excitors) and the inhibitory Khi cell (K heart inhibitor). The fourth class, tonus pericardium excitor (Tpe), modulates the heart by action on pericardial tissue. 3. Pharmacologic, electrophysiological, and anatomic evidence is presented that shows that these cells are motoneurons, innervating heart muscle fibers directly: blocking central chemical synapses failed to prevent the actions of the neurons on the heart; simultaneous intracellular recordings showed unitary EJPs in heart muscle after 1:1 and with constant delay from evoked neuronal action potentials; intracellular injection of the dye Lucifer yellow showed all cells had axonal branches entering the intestinal nerve (which innervates the heart). 4. The use of selective antagonists to 5-hydroxytryptamine (5-HT) (cinanserin), dopamine (ergonovine), and acetylcholine (alpha-bungarotoxin) provided evidence that the actions of She and Hhe cells are mediated by 5-HT, whereas those of the Khi cell are mediated by acetylcholine. 5. A cyclically active network of three interneuronal inputs acting on the heart motoneurons is described. 6. One of these, input 3, is responsible for periodic excitation of the heart via its effects on the Hhe cells.

scholarly journals Acute Effect of Pore-Forming Clostridium perfringens ε-Toxin on Compound Action Potentials of Optic Nerve of Mouse

eNeuro ◽  
2017 ◽  
Vol 4 (4) ◽  
pp. ENEURO.0051-17.2017 ◽  
Author(s):  
Mercè Cases ◽  
Artur Llobet ◽  
Beatrice Terni ◽  
Inmaculada Gómez de Aranda ◽  
Marta Blanch ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Clostridium Perfringens ◽  
Action Potentials ◽  
Acute Effect ◽  
Compound Action Potentials ◽  
Compound Action

Stretch of mammalian nerve in vitro: Effect on compound action potentials

2000 ◽  
Vol 5 (4) ◽  
pp. 227-235 ◽  
Author(s):  
Sidney Ochs ◽  
Rahman Pourmand ◽  
Kenan Si ◽  
Richard N. Friedman
Keyword(s):  
Action Potentials ◽  
Compound Action Potentials ◽  
Vitro Effect ◽  
Mammalian Nerve ◽  
Compound Action
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