ABSTRACT
An electrophysiological bioassay system has been developed to provide safety-related information about the functional consequences of non-thermal laser irradiation of the vertebrate retina. This in vitro preparation allows precise dosimetry at the retinal surface, provides for an intra-retinal control, comparing lased vs non-lased tissue, and permits quantitative assessment of the biophysical mechanisms of laser-induced retinal dysfunction.
Subject(s)
Eye/radiation effects , Lasers/adverse effects , Animals , Computers , Electroretinography/instrumentation , Electroretinography/methods , In Vitro Techniques , Optics and Photonics/instrumentation , Photoreceptor Cells/radiation effects , Retina/radiation effects , TurtlesABSTRACT
Direct-current magnetic fields of 10 to 100 gauss cause a significant short-term reduction of the in vitro electroretinographic b-wave response in turtle retina. This response compression is not accompanied by the usual reduction in retinal sensitivity that occurs with background illumination. Furthermore, this effect is obtained only briefly after the offset of ambient lighting in the diurnal light-dark cycle of nonhibernating animals.
Subject(s)
Magnetics , Retina/physiology , Turtles/physiology , Animals , Circadian Rhythm , Electroretinography , Hibernation , Rhodopsin/physiologySubject(s)
Eye Movements , Pons/physiology , Reticular Formation/physiology , Superior Colliculi/physiology , Abducens Nerve/cytology , Abducens Nerve/physiology , Action Potentials , Animals , Attention/physiology , Evoked Potentials , Haplorhini , Motor Neurons/physiology , Neurons/physiology , Reaction Time , Reticular Formation/cytology , Saccades , Superior Colliculi/cytology , Synapses/physiologyABSTRACT
Single-unit recordings in the frog's optic tectum have demonstrated the existence of a systematic spatial separation between the direct contralateral and indirect ipsilateral excitatory receptive fields. Marked differences in this spatial organization were found between paralyzed and anesthesized animals. Significant latency differences were found between sustained (class I/II) and transient (class III) contralateral fibers. Corresponding latency differences were also seen in ipsilaterally driven responses. It is suggested that there may be at least two different classes of ipsilateral fibers. The existence of binocular interaction at the level of the afferent terminal arborizations was investigated, utilizing temporally asynchronous dichoptic stimulation. No such phenomena were seen in curarized animals. These findings are discussed in terms of possible velocity and direction sensitivity mechanisms.
