Biomedical subjects

V C Pellis

Publications and source records attributed to V C Pellis.

27 records · Page 2Linked to original sources

PubMed1988

Escalation of feline predation along a gradient from avoidance through "play" to killing.

In this article, we show that feline predation involves a continuous gradient of activation between defense and attack and that predatory "play" results from an interaction of the two. Benzodiazepines (oxazepam, diazepam) escalated attack toward killing, so that cats that had avoided mice prior to the drug now played with them, cats that had originally played now killed, and cats that killed mice now did so with less preliminary contact. In such shifts, no sharp demarcation between play and predation was evident. Lateral hypothalamic lesions disrupted the escalation of attack. During recovery, attack was escalated once again along the gradient toward killing, but in the absence of both defense and play. A similar result was obtained in intact killers and nonkillers by the application of mild tail pinch. These results suggest that play with prey is a misnomer for predatory behavior that fails to escalate along the gradient between defense and attack. Movement notation analysis revealed that playful movements are adaptive in that they protect the cat from injury.

Aggression↗

PubMed1987

'Axial apraxia' in labyrinthectomized lateral hypothalamic-damaged rats.

Contact righting, that is, turning from a recumbent position to prone, is abolished for a few days after large electrolytic lesions of the lateral hypothalamus. With recovery, contact righting reappears, but does so in a distinct manner. At first the body is righted by backleg movements, in the absence of any active axial rotation. Later, righting switches from back to front, so that righting begins in the shoulders and then proceeds to the pelvis. Such righting is achieved by axial rotation, that is, the limbs are carried by the torso, rather than vice versa. Labyrinthectomy, when combined with lateral hypothalamic (LH) damage, slows this recovery (now taking as long as 3 weeks), and reveals many intermediate stages of contact-righting. The absence of axial rotation in the early stages of recovery from combined LH damage and labyrinthectomy is compared to the 'axial apraxia' seen in some parkinsonian patients.

Animals↗

PubMed1987

Sex differences in the effects of haloperidol, morphine, and their combination on colonic temperature in rats.

Previously it was found that during the loss of postural support induced by combined administration of haloperidol and morphine, rats became markedly hypothermic. The present work was a more detailed study of this hypothermia. Morphine alone (20 mg/kg) produced a slight hyperthermia (1 degrees C) in female rats and no effect in males. Haloperidol alone (5 mg/kg) elicited a hypothermia of about 3 degrees C in females and no effect in males. The combination of both elicited a greater decrease of temperature (about 5 degrees C) in female rats and, unexpectedly, a decrease of 3 degrees C in males. According to these data, increased endorphinic activity with a concomitant decrease in dopamine in some unidentified regions of the central nervous system causes hypothermia.

Animals↗

PubMed1987

Pharmacological subtraction of the sensory controls over grasping in rats.

Catecholamine-depletion-induced catalepsy isolates and leaves intact an aggregate of allied reflexes (e.g., righting, standing still, bracing, and clinging) which involve all the body and limb segments in defending stable static equilibrium. Because other movement subsystems (locomotion, orienting, scanning, directed use of mouth or forepaws) are depressed, such animals cling in a vertical position for an abnormally long period of time. As a consequence, grasping reflexes may be studied independently of other responses. Haloperidol, a dopamine antagonist, abolishes visually elicited reaching and grasping, but leaves intact tactile and proprioceptive control of grasping. The grasping of haloperidol-treated rats can be further simplified by the pharmacological removal of the remaining sensory controls. The addition of morphine to haloperidol abolishes tactile grasping, while the addition of diazepam to haloperidol abolishes both tactile and proprioceptive (traction-elicited) grasping. Although visual, tactile, and proprioceptive grasping are abolished by haloperidol-plus-diazepam, some vestibular input to clinging remains: such rats, in response to being held vertically upright in the air, flex their digits with sufficient strength to allow them to cling vertically. The strength of forepaw digit flexion is severely diminished by labyrinthectomy, but the digits of the hindpaws appear to be unaffected. This residual non-labyrinthine digit gripping appears to be induced by proprioceptive inputs from the head, neck and torso in response to the vertical body position. Wrapping an elastic bandage snugly around the head and neck of a labyrinthectomized rat given haloperidol-plus-diazepam further diminishes the strength of forepaw digit flexion, and to a lesser degree hindpaw digit flexion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Abnormal gait sequence in locomotion after atropine treatment of catecholamine-deficient akinetic rats.

Excessive, abnormal locomotion occurs after a high dose (25-50 mg/kg) of atropine sulfate to rats already akinetic due to catecholamine deficiency from intraventricular administration of 6-hydroxydopamine. This abnormal locomotion involves an abnormal gait sequence [right (R) hindleg (H), left (L) foreleg (F), LH, RF] instead of the normal gait sequence (RH, RF, LH, LF). In such animals atropine progressively (i) decreases hindleg step size, (ii) decreases arching of the trunk, and (iii) increases foreleg step size. These factors combine to change the ratio of front/hind body support. If the body stretches too far and the hindleg step is too small, a given hindleg step supports insufficient weight to remove weight from the ipsilateral foreleg; consequently, the opposite foreleg must execute the next step, producing the abnormal gait sequence. Thus, atropine affects gait sequence indirectly; it acts on at least three variables that affect how body weight is distributed and shifted during locomotion. To maintain stability during such locomotion, gait sequence is appropriately altered.

Animals↗

PubMed1986

Morphine subtracts subcomponents of haloperidol-isolated postural support reflexes to reveal gradients of their integration.

Although cataleptic rats do not spontaneously orient, scan, or walk, they will cling, stand, right themselves in the air, and resist being displaced from a stable position (Schallert, Whishaw, De Ryck, & Teitelbaum, 1978). Morphine produces a state of immobility in which all reflexes used for stable static support (e.g., standing, righting, clinging, and bracing) appear to be inhibited (De Ryck, Schallert, & Teitelbaum, 1980). Addition of morphine to haloperidol abolished or reduced those reflexes used to defend against slow postural displacements (e.g., bracing) but left intact those used to protect against fast postural displacements (e.g., righting in the air). However, although intact, these responses to fast postural displacements were completely abolished by labyrinthectomy, showing that they were controlled only by vestibular inputs. During recovery from morphine's effects, the responses to slow postural displacements reemerged, revealing fractional subcomponents. Furthermore, the reorganization of the subcomponents proceeded along specific body gradients; for example, bracing and standing reemerged caudorostrally, while at the same time, righting and clinging reemerged rostrocaudally.

Animals↗

PubMed1985

Previous experience disrupts atropine-induced stereotyped "trapping" in rats.

Three experiments were conducted to investigate the phenomenon of atropine-induced stereotypic trapping in rats reported by Schallert, De Ryck, and Teitelbaum (1980). The first two showed that such trapping was disrupted by previous experience with the specific trapping task or the test context alone. The third showed that, in response to the test context, specific behaviors were altered in rats experienced with the context. Inexperienced atropine-treated animals moved slowly and showed a strong thigmotaxis to surfaces with the body and particularly the snout. The hindquarters did not cooperate well with the movements of the forequarters. In contrast, atropine-treated animals familiar with the context moved with medium-speed, coordinated movements, were independent of surface contact with body and snout, and the hindquarters cooperated fully with forequarter movements. These reactions of drugged animals were exaggerated forms of those of undrugged animals to the unfamiliar and familiar context, respectively. Thus, atropine enhances the reactions of the rat to both a novel and a familiar environment. The enhanced reactions to a novel environment appear as stereotyped behaviors that trap the animal in particular configurations of surfaces. The enhanced reactions to a familiar environment abolish the stereotypic trapping normally produced by atropine. This pattern of results indicates that it is not atropine per se that leads to trapping. Rather, stereotypic trapping develops as a consequence of an interaction between the adaptive responses of the rat to a novel environment and atropine.

Animals↗

PubMed1983

Locomotor-rotational movements in the ontogeny and play of the laboratory rat Rattus norvegicus.

During postnatal development, young laboratory rats, Rattus norvegicus, exhibit a variety of locomotor-rotational movements, that is, runs and jerk-jumps, in both playful and nonplayful contexts. The frequency of movement types differed between contexts. Some contexts, such as exploration and sleeping, contained spontaneously (i.e., possible eliciting stimuli were not observed) occurring jerk-jumps which varied with increasing age. In some contexts, such as social play, in which locomotor-rotational movements were elicited by observed stimuli, the frequency of jerk-jumps remained similar throughout ontogeny. During social play some locomotor-rotational movements were found to have immediate functions, such as achieving advantage over the partner during play-fighting, and as a means of terminating sensory input from the partner at the end of social contact.

Age Factors↗

PubMedDate not supplied

Uses of vision by rats in play fighting and other close-quarter social interactions.

Enucleated juvenile rats were compared to sighted juveniles, and tested over six trials. In some of these trials, the vibrissae were clipped and the test chamber was flooded with white noise. Even though the enucleated rats played, they did so in an atypical manner. They tended to initiate more playful and other social contacts, and were more likely to defend themselves if contacted. When they did defend themselves, they adopted behavior patterns that were more likely to evade the partner's attack. In addition, the enucleated rats were hypersensitive to the partner, being more likely to respond defensively when contacted further from the nape (the main play target). All these changes in play fighting by nonsighted rats suggest that the loss of vision leads to motivational changes in activity and reactivity, and so has an indirect effect on play behavior. In addition, direct evidence is also provided to show that vision is used to orient attacks to the nape. When the vibrissae were closely clipped, the sighted rats continued to make direct attacks on the partner's napes, whereas the nonsighted rats did not. Rather, they first contacted some other part of the partner's body and then oriented to the nape. Another test paradigm was used to determine whether vision is used to trigger defensive responses. The rats were partially food deprived as adults and were filmed in a food wrenching and dodging situation where one rat was given a food pellet and the other allowed to steal it. Measurement of the distance at initiation of the lateral swerve away from the approaching partner (i.e., dodge) showed that when the vibrissae are clipped, the sighted rats continued to initiate dodges at the same distance, whereas the nonsighted rats could not. Therefore, vision appears to have an active role in organizing movement sequences of attack and defense in play fighting and other close-quarter interactions.

Aggression↗