The neuronal components of the optic nerve of the crayfish as studied by single unit analysis

Abstract

Unit responses were obtained from the optic nerve of the crayfish, Procambarus clarki (Girard) with steel needles. Eighty-three repeatedly recognized elements are described. They range from bundles of primary sensory fibers to complexly reacting multimodal interneurons. Visually reacting fibers fall into two main classes, one class reacts tonically to overall illumination, the other responds to moving objects. Sustaining fibers react to increased light with increased output, dimming fibers are active in the dark and inhibited by light. Fourteen sustaining and four dimming fibers are described. The main movement fiber type, of which eleven have been found, responds to shadows. They "habituate" quickly and react best to movement of small black objects. All these fibers, and some others, are present as centrifugal elements from the other eye. Four fibers, two sustaining and two movement ones, change their fields with position of the animal. These "space-constant" fibers "look" at the sky from all positions for which possible and are otherwise "blind." Mechanoreceptive interneurons form a bundle between the first and second classes of optical fibers.Seventeen members are described. Five multimodal fibers, with combined visual and mechanoreceptor input are described. Maps of the approximate locations of the units in the cross-section of the optic nerve are presented. The number of times specific fibers were found exceeded 50 for 28.

Polarization sensitivity in the red swamp crayfish Procambarus clarkii enhances the detection of moving transparent objects

“…P. clarkii are sensitive to moving visual stimuli over a velocity range of at least four orders of magnitude (Glantz, 2001), indicating that motion detection is a critical component of the crayfish visual system. A significant portion of the primary visual synapse (Glantz and Bartels, 1994) and the ascending optic tract (Wiersma and Yamaguchi, 1966) are devoted to motion sensitivity. Glantz (Glantz, 2001) proposed that the polarization sensitive-neurons might also contribute to this pathway.…”

The visually evoked defense reflex of the crayfish: Habituation, facilitation, and the influence of picrotoxin

“…First, evidence reported by Wiersma (1970aj suggests that the defense reflex receives substantial input from the previously documented (Wiersma and Yamaguchi, 1967a) space constant motion detectors. Secondly, preliminary studies in this laboratory have consistently indicated that the stimulus conditions (e.g., discontinuous motion of dark objects) necessary to elicit the defense reflex are very similar t o the optimal conditions for eliciting activity in the jittery motion detectors (Wiersma and Yamaguchi, 1966). Furthermore, the motion detectors of the crayfish are known to undergo pronounced habituation with repeated stimulation to the same retinal area Yamaguchi, 1966,1967aj.…”

Neuronal processing of translational optic flow in the visual system of the shore crabCarcinus maenas

“…In crayfish, a class of visual interneurones known as sustaining fibres, initially called tonic 'on' neurones by Wiersma and Yamaguchi (Wiersma and Yamaguchi, 1966;Wiersma and Yamaguchi, 1967), have their main dendritic tree in the medulla (Kirk et al, 1982) and respond to a light pulse with a phasotonic discharge that persists for the duration of the stimulus and is followed by an inhibitory 'off' response (Kirk et al, 1983;Pfeiffer and Glantz, 1989). They are additionally directionally selective to movement (Glantz et al, 1995) (Fig.7A) and the response to light pulses (Fig.9A) are identical to those described above for such fibres.…”

“…Early work identified response properties of interneurones of the optic nerve to simple stimuli. These included sustaining fibres, dimming fibres and several classes of motion detectors (Waterman et al, 1964;Wiersma, 1966;Wiersma and Yamaguchi, 1966;Wiersma and Yamaguchi, 1967;York and Wiersma, 1975) (reviewed in Wiersma et al, 1982). Subsequent studies based on intracellular recording and Lucifer Yellow injections confirmed the identity of many of the sustaining fibres (Kirk et al, 1982;Kirk et al, 1983).…”