Limulus Lateral Eye Research Articles

Modification of the receptor potential of the Limulus lateral eye by current and light

Effects of intracellularly injected current and light adaptation on the receptor potential of retinular cells in the lateral eye of Limulus polyphemus were investigated. Hyperpolarizing currents injected directly into monitored retinular cells produced an increase in membrane potential, increased the delay of the receptor potential and strong currents reduced its amplitude. Hyperpolarizing currents injected into neighboring retinular cells increased the membrane potential but delayed the receptor potential slightly or not at all. Hyperpolarizing current injected into eccentric cells produced variable effects. It is probable that the direction of current flow across low resistance junctions in the rhabdomere of retinular cells is responsible for the observed modification of the receptor potential. Light adaptation decreased the magnitude and latency of the receptor potential, effects which are prevented by direct but not by indirect hyperpolarization. It is possible that the effects of light adaptation may result from ionic imbalances in the restricted extracellular space around the microvilli. The receptor potential polarity is reversed on the positive side of zero membrane potential.

Retinular and eccentric cell morphology in the neural plexus of Limulus lateral eye.

AbstractRetinular and eccentric cells of Limulus lateral eye are stained by intracellular iontophoretic injection of Procion M4R. Eccentric cell branching can be divided into multiple neuropile, long lateral branches and distal collaterals. Retinular cells possess only short axon spines. This morphology is discussed in relation to the known physiology of cell interactions.

Neuropharmacological modification of response characteristics of sense cells in the limulus lateral eye

Perfusion of the excised lateral eye of Limulus with sea water solutions of epinephrine, norepinephrine or dopamine increased the frequency of the spontaneous and light-initiated spike discharge and slightly depolarized eccentric and retinular cells; perfusion with solutions of 5-hydroxytryptamine and γ-aminobutyric acid decreased or abolished the spike discharge and hyperpolarized eccentric cells more than retinular cells. Small volumes (2–3 μl) of solutions of 5-hydroxytryptamine or γ-aminobutyric acid were most effective when applied behind the ommatidium under study. Ethanol blocked the inhibitory action of 5-hydroxytryptamine more effectively than that of γ-aminobutyric acid. These results suggest but do not prove that some or all of these substances play a role in the transmission of information in the visual system of the lateral eye of Limulus.

Increment sensitivity of the eye of Limulus

Инкpeмeнтaльнaя хyвcтвитeльнocть eдинихнoгo oммaтидия лaтepaльнoгo глaзa лимyлюc (Limulus) былa иccлeдoвaнa c пoмoщью кpaтких тecтoвых вcпышeк, нaлaгaeмых нa aдaптиpyющee пoлe. Были oпpeдeлeны интeнcивнocти вcпышeк, тpeбyющихcя для вызывaния пopoгoвых peaкций пpи paзлихных интeнcивнocтях aдaптиpyющeгo пoля. Oтнoшeния peзyльтиpyющeй инкpeмeнтaльнoй хyвcтвитeльнocти были cхoдными пo фopмe c дaнными инкpeмeнтaльных пopoгoв хeлoвeкa и кpивыми, вывeдeнными пpи peгиcтpaции пoтeнциaлoв гaнглиoзных клeтoк ceтхaтки. Oднaкo, пoлyхeнныe peзyльтaты нe cooтвeтcтвoвaли ни зaкoнy Beбepa, ни зaкoнoмepнocти кopня квaдpaтнoгo. He былo нaйдeнo измeнeний ни в фopмe, ни в нaклoнe кpивых, выpaжaющих эти oтнoшeния пpи дoбaвлeнии лaтepaльнoгo тopмoжeния, дaвaeмoгo aдaптиpyющим пoлeм или жe yвeлихeниeм cвeтoвoй aдaптaции в пpeдeлaх 6 лoгapифмихecких eдиниц.

On tuning and amplification by lateral inhibition.

Lateral inhibition in a neural network generally attenuates the amplitudes of the responses to sinusoidal stimuli-both spatial and temporal. For an inhibitory influence with an abrupt onset and an exponential decay in time, and with a Gaussian distribution in space (the forms often assumed in theoretical calculations), the attenuation is greatest at low temporal and spatial frequencies. The attenuation diminishes with increasing frequencies until ultimately the amplitudes of inhibited responses become equal to, but never exceed, the amplitudes of the uninhibited. For an inhibitory influence with a delay to the maximum in time or with eccentric maxima in space, however, the amplitudes of inhibited responses to certain intermediate frequencies may be greater than those of the uninhibited respones. This "amplification" results because the delay and the spatial separation "tune" the network to particular temporal and spatial frequencies; the inhibition is turned on at the trough of the response and off at the crest, thus tending to produce the greatest possible amplitude. The amplification has been observed in one neural network, the retina of the lateral eye of Limulus. The basic principles are general, and the effects may be expected in any system with negative feedback.

Dual Response of the Limulus Lateral Eye to Electric Stimulation

Dual Response of the Limulus Lateral Eye to Electric Stimulation