Leonard Kass

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The optic tectum of pit vipers (Crotalinae) contains a layer of infrared-sensitive neurons subjacent to the visual layer; these indirectly receive input from the facial pit organs. They respond transiently to the appearance or motion of warm objects within their 25 degrees to 70 degrees excitatory receptive fields (some have inhibitory regions) and(More)
A circadian clock in the brain of the horseshoe crab, Limulus polyphemus, has an important role in the function of the peripheral visual system. At night, the clock transmits neural activity to the lateral, ventral, and median eyes via efferent optic nerve fibers. The activity occurs in synchronous bursts (maximum rate of 2 bursts/s) with individual(More)
Efferent fibers from a central circadian clock innervate photoreceptors along the ventral nerve of Limulus and release octopamine when active. We have recorded ERG-like responses from the ventral eye in vivo over several day periods. We have also used intracellular microelectrodes to study changes in ventral photoreceptor function during exogenous(More)
We have studied the connections of the tectum of the rattlesnake by tectal application of horseradish peroxidase. The tectum receives bilateral input from nucleus lentiformis mesencephali, posterolateral tegmental nuclei, anterior tegmental nuclei and periventricular nuclei; ipsilateral input from nucleus geniculatus pretectalis, and lateral geniculate(More)
The receptor specificity for synaptically mediated lateral inhibition in Limulus lateral eye retina was studied by structure-activity correlations of the action of the putative indoleaminergic neurotransmitter, serotonin (5-HT), and its isomers and structural analogs, tryptamine (TRYP), 6-hydroxytryptamine (6HT), 5,6-dihydroxytryptamine (5,6-DHT),(More)
We investigated the action of LSD at the putative indoleaminergic lateral inhibitory synapse in the lateral eye of Limulus polyphemus. We recorded extracellular and intracellular voltage responses from eccentric cells while producing inhibition either by light or by antidromic stimulation of the optic nerve in the presence of LSD, serotonin (5-HT),(More)
Visual and infrared cell layers were identified in the tectum of the pit vipers Crotalus viridis and Sistrurus melitus. Histologic reconstructions of 48 lesions utilizing the Prussian Blue technique were correlated with micrometer depth readings for 251 visual, infrared and bimodal single unit recordings. The visual cell layer extends caudally from(More)
The ability of mixed spinal nerve roots to regenerate and reinnervate the urinary bladder was examined in young adult female cats. Using microsurgical technique, a unilateral extradural spinal nerve root anastomosis of a lumbar (L7) to a sacral root (S1) either with or without a nerve graft was performed. Remaining ipsilateral sacral roots were transected.(More)
Exploration of deep-sea hydrothermal vents over the past quarter century has revealed that they support unique and diverse biota. Despite the harsh nature of the environment, vents along the Mid-Atlantic Ridge are dominated by large masses of highly motile Bresiliid shrimp. Until 1989, when it was discovered that the vent shrimp Rimicaris exoculata(More)