Article Figures & Data
Figures
- Fig. 1.
Chronic preparation. A, Recording (R) and stimulating (S) electrodes were implanted as indicated. Recording electrodes were placed dorsal to the cord (C), where they detected the firing of int A as small spikes (dot in inset) and LG firing as large spikes (triangle in inset). The stimulating electrodes lie over afferent-containing roots; the number of fibers that fire increases as a function of stimulus intensity.B, Circuit of afferent portions of LG reflex indicating parts of circuit activated by stimulating electrodes (Stim) and detected by recording electrodes (Rec).
- Fig. 2.
Results from a typical experimental session. Eachpoint shows the stimulus level applied on a trial (stimulus scale arbitrary). Filled symbols indicate that the LGs (circles) or interneuron A (squares) fired, and open symbolsindicate that they did not. Animals were separated during periods I and III and were together during period II. Letters indicate what the animal was doing at the time each stimulus was given during period II (see Table 1 for codes).
- Fig. 3.
Measures of threshold and response probability illustrated. Each panel shows pooled data from several sessions on a single animal. The left panel shows period II trials during which a dominant animal was still but maintaining a dominant posture; the right panel show all trials during period I of the same sessions. At the bottom of each panel is a scatter plot of stimulus levels presented, with those that caused responses shown as filled symbols. Stimulus levels are normalized to the baseline threshold for the session in which they were presented (i.e., they were divided by the average of the threshold voltage during periods I and III for the session). At thetop of each panel is shown the best-fitting logistic curve of probability of response as a function of normalized stimulus strength for the data below (see text). The marker at probability 0.5 on the left panel indicates the maximum likelihood values of T ± S. The mean of the curve over normalized stimulus strengths 0–8 is shown as dashed lines.
- Fig. 4.
Resting excitability of LG reflex. Scatter plot of ratios of LG to interneuron A threshold are averaged over all periods I for each animal.
- Fig. 5.
LG thresholds of dominants and subordinates during encounters. For each period, LG thresholds, taken as averages of estimates from individual threshold crossings (see Data Analysis), were normalized to period I values. A, All experimental sessions; thresholds for each session are joined by aline. Period III was divided into halves (a and b); for clarity only, IIIb values are shown here.B, Data averaged across animals. Data for control (see Materials and Methods) as well as for experimental sessions are shown.
- Fig. 6.
Behavioral differences between dominants and subordinates. The mean number of occurrences per session during period II is shown for each category of behavior.
- Fig. 7.
LG reflex excitability associated with different behaviors. For this figure, data from all animals were pooled, and stimulus levels from an encounter were normalized to the average of periods I and III for that encounter.
- Fig. 8.
Degree of suppression during specific behaviors.Black bars show suppression index for behaviors, the codes of which are indicated (see Table 1) and calculated from pooled data of Figure 7; open circles show suppression indices for individual animals.
- Fig. 9.
Variability of LG reflex thresholds during periods of suppression from single sessions on subordinates. Raw stimulus strengths, rather than normalized values, are shown. Duringpre and post tests threshold was well defined, but during R and C activities thresholds were erratic. During each test thresholds seemed to vary between the levels marked as 1 and 2(arrows).
- Fig. 10.
Nongiant escape response of a subordinate during an agonistic encounter. A, Lateral giant response evoked by experimenter-produced abdominal tap. B, Medial giant response evoked by experimenter-produced tap of cephalothorax.C, Response occurring during agonistic encounter.Dots mark giant axon spikes. Slower potentials are phasic flexor muscle potentials. Calibration, 2 msec.
Tables
V, Vigorous claw grappling C, Claw grappling A, Approaching other animal T, Touching other animal D, Dominant posture (raised open claws, standing high, center of tank, facing other animal) R, Retreating from other animal S, Submissive posture (facing away from other animal, at margin of tank, thorax close to substrate, claws touching substrate) B, Being touched U, Unspecified definite movement Q, Quiescent (not moving, no recognized agonistic posture) G, Gravel manipulation* F, Flipping* ↵* Rarely seen just preceding stimulations and not included in Figures 6, 7, 8.
