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Local anesthesia of the facial epidermis can effect a substantial decrease in shock-elicited fighting of paired rats. The present experiments constitute methodological extensions to mouse killing and spontaneous drug-induced social aggression. In the first experiment, known mouse-killing rats were given bilateral lidocaine or placebo injections administered under ether anesthesia. Attack and kill latencies were significantly longer under lidocaine than under placebo; all subjects killed under placebo, whereas a third of all subjects failed to kill on the initial lidocaine test. On subsequent lidocaine testing, latencies decreased and nonkilling rats killed. In a second experiment intense apomorphine-induced conspecific fighting of rats preselected for aggressiveness was markedly reduced following lidocaine anesthesia. The comparative results of both experiments are interpreted in reference to theoretical assertions regarding the import of sensory information in stimulus-bound attack and the typology of central aggression systems.

Selected pairs of agressive rats fighting reliably and at relatively high levels were successively treated with lidocaine anesthesia of the vibrissal pads prior to each daily test session. The initial decrement in fighting was substantial, but after only three sessions pretest level of fighting was regained. Initial decrease in fighting of a second group following removal of all vibrissae was comparable to that produced by local anesthesia, but recovery of fighting to pret~st levels was slower and less complete. The results suggest that intact and functional vibrissal organs are not mandatory for normal fighting when Ss are given sufficient preliminary fighting experience to footshock. Applications of vibrissal sensory deprivation techniques for control of fighting in experimental designs calling for repeated measures or sequential treatments are potentially liable to confounding.Historically, investigators have long recognized the import of rodent vibrissal organs in providing proximal sensory information. Early monographs by Richardson (1909) and Vincent (1912) reveal interests stemming from reports of successful maze performance by blind and anosmic rats and the presumed interactive roles of the senses as defined by characteristics of the experimental task . Watson (1907) compared the maze performance of blind, anosmic, and normal rats before and after being devibrissaed . Although immediate performance was im paired, no decrement in running time was observed 24 h after being devibrissaed; Watson concluded that removal of the vibrissae had no effect when sufficient time was allowed for adaptation. Richardson (1909) also found that tactual sensation from the vibrissae was unnecessary after learning had occurred in a platform jumping task.More recently, Schiffman, Lore , Passafiume, and Neeb (1970) tested hooded and albino rats on a visual cliff apparatus providing both visual and tactual depth cues. Devibrissaed rats showed a marked preference for descent on the shallow side of the visual cliff, whereas intact controls showed no significant preference for either side. Rats apparently do not apply visual information unless forced t6 do so by a center-board height preventing vibrissal contact with the glass surfaces. Tactual information from the vibrissae may thus be prepotent over visual information on this depth-perception test. Schiffman et al (1970) suggested that visual discrimination on a number of visual tasks may be substantially improved by removal of the vibrissae.

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Local anesthesia of the mystacial epidermis with Lidocaine HCl reliably decreased shock-elicited fighting in 8 pairs of mature male Long-Evans rats. The decrease in aggressive responding was approximately twice as great as that reported for devibrissaed rats. Subsequent fighting, 3-hr. post-injection, did not differ from control or pre-injection baselines. Recording of intense vocalization accompanying fighting yielded objective data comparable to attack scores visually observed and allowed an independent measure of depressed fighting behavior. The results are discussed in reference to the import of tactual orientation for guiding directed attack and the relative merits of the technique as a vehicle for further investigation.

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Light and dark reared, social and isolate housed, male Long-Evans hooded rats were tested in bright and dim light for aggressive response to footshock. Test lighting and socialization main effects were significant, with greater fighting in dim light than in bright light and greater fighting by isolates than by socially housed animals. Test lighting interacted with prior visual experience and socialization interacted with past and present illumination variables. The results suggest an inhibitory effect of test illumination dependent upon prior social and visual experience.The importance of posture and related threat (Knutson & Hynan, 1972: Reynierse, 1971Vernon, 1969) would appear to implicate visual cues as significant variables in shock-elicited aggression of rats. Flory, Ulrich, and Wolff (1965) investigated the influence of visual impairment by fitting leather hoods over the heads of their Ss. The rats were paired and given shocks over repeated sessions with and without the hoods in place. Hooding decreased fighting by approximately 50%. In a second experiment, a pair of blinded rats fought 27% less than prior to blinding; when also devibrissaed, the same pair fought at lower levels. The decrease in fighting originally noted with the use of hoods was attributed to both visual and tactual sensory restriction. More recently, Bugbee and Eichelman (1972) have compared pre-and postoperative fighting of blinded, devibrissaed , and bulbectomized rats, Contrary to the results of Flory et al (1965), no decrement in fighting was observed after blinding. Bulbectomized rats fought at near preoperative levels, while devibrissaed rats fought significantly less. Olfactory and visual factors were presumed to have a minor, if any, role in conspecific aggression.The present investigation sought to assess the role of past and present illumination on shock-elicited aggression. Visual history was manipulated by housing animals in light or darkness, and immediate visual cues were examined by testing in bright or very dim light. Prior social history (isolate or group housing) and aggressive experience (successive fights) were also examined for interactive effects with illumination variables. METHOD SubjectsSs were 48 male Long-Evans hooded rats. *Supported by NIH Research Grant MH 21577-01. ApparatusThe fighting chamber, a 20 x 20 x 20 em box of wood and Plexiglas, was enclosed within a fan ventilated light-and sound-attenuating chamber having a viewing portal and a 100-W incandescent lamp (mounted in a recessed ceiling fixture) that illuminated the fighting chamber. The grid floor of the fight chamber consisted of Y4-in. brass rods spaced 5{8 in. apart. Constant current shock was delivered from a Lafayette A-615A shock source through a Lafayette 5820 neon grid scrambler. ProcedureAll Ss were reared from birth with their littermates in constant darkness until weaning. At weaning, female pups were culled and the remaining male pups were randomly assigned to group pan cages containing four Ss each. At 45 days of age, half (N = 24) we...

Possible daily periodicity in experiments involving conditioned behaviors has not usually been investigated or controlled. The present experiment argues for such studies in that variation in the performance of a free-operant avoidance task by 30 rats was detected as a function of when during the 24-hr. day behavioral testing occurred. In terms of shocks avoided, performance was best in the middle of the dark phase of the day and worst late in the light phase. The absence of a similar rhythm in the operant response rate suggests the 24-hr. periodic change in efficacy of avoidance was not related to diurnal variation in general activity levels. Implications of daily periodicity are discussed in terms of experimental procedures and controls.