Wire Mesh Cages Research Articles

Ultrasounds emitted by female rats during agonistic interactions: effects of morphine and naltrexone.

Ultrasonic vocalizations may be an expression of the affective pain response in laboratory rodents. The present experiment compared morphine's effects on high (33-60 kHz) and low (20-32 kHz) frequency ultrasonic vocalizations to its effects on a range of unconditioned behavioral responses to aversive stimuli; the influence of estrous cyclicity on morphine sensitivity was also investigated. In experiment 1, naive female Long-Evans rats, selected during estrus or diestrus, received cumulative morphine (1, 3, 6, 10 mg/kg SC) or saline, and in experiment 2, rats were pretreated with naltrexone (0.1 mg/kg IP) 5 min before morphine (17, 30, 60, 100 mg/kg SC). The following endopoints were measured 20-25 min post-injection: (1) tail flick latency; (2) ultrasonic and audible vocalizations; (3) the behavioral response to aggressive attack; and (4) locomotor activity. Following a brief exposure to an attack, rats were threatened by an aggressor but protected from further attack by a wire mesh cage (30 x 21.5 x 20 cm), thereby allowing for continued behavioral and vocal measurement without the risk of physical injury; video and audio recordings were made of the attack encounter and a subset of the protected encounter (1 min). The endpoint most potently and specifically modulated by morphine was high frequency ultrasounds. The rate of high frequency calling varied as a function of the estrous cycle, supporting gonadal hormone modulation of ultrasonic vocalizations. Low frequency ultrasounds, by contrast, were relatively insensitive to opiate manipulation and were less influenced by estrous cyclicity. High frequency vocalizations may be a more sensitive indication of the affective response to an attacking conspecific that low frequency calls.(ABSTRACT TRUNCATED AT 250 WORDS)

Maternal labelling is not necessary for the establishment of discrimination between kids by recently parturient goats

Abstract. A series of experiments was conducted to assess the hypothesis that chemical labels acquired by newborn kids from their mother may be important for the females' acceptance of their own offspring and rejection of alien young. In an initial experiment, recently parturient goats, Capra hircus L., were tested for their responses to their own familiar offspring and two alien kids of the same age: one that had been kept with its mother after birth (and therefore presumably labelled by her) and one that had been isolated since birth. While all 15 females accepted their own kid, 12 rejected both the labelled and unlabelled alien. Thus, labelling of kids by their mother is not necessary for their later rejection by an alien female who has established a selective bond with her own neonate. Kids in a second experiment were placed into a wire-mesh cage at birth that prevented their mother from licking or nursing them. At approximately 4·5 h postpartum, seven out of 18 goats failed to display maternal behaviour to either their own or alien kids. While all the remaining females accepted their own kid, significantly fewer (6/11) accepted an unlabelled alien. Although the cage manipulation appeared to disrupt maternal behaviour in a large proportion of females, it is none the less evident that mother goats are capable of recognizing their own offspring and discriminating it from an alien isolated kid, even when there is no opportunity for maternal labelling. Overall these two experiments suggest that when mothers and kids are left undisturbed after parturition, maternal labelling is not a necessary step for the establishment of selective care.

Diazepam and gepirone selectively attenuate either 20-32 or 32-64 kHz ultrasonic vocalizations during aggressive encounters.

Ultrasonic vocalizations (USV) in rats may communicate "affective" states, as they occur only in highly significant behavioral contexts such as during sex, aggression, exposure to painful or startling events. This proposal was evaluated in an experiment with adult male Long-Evans rats during agonistic encounters; specifically, the effects of diazepam, flumazenil and gepirone were studied on different types of USV emitted by intruder rats exposed to resident attacks and to "threat of attacks" (i.e., intruder protected within the home cage of the resident by a wire mesh cage). USV were readily emitted during agonistic encounters and consisted primarily of two distributions of pure tone whistles: 0.3- to 3-s, 20- to 32-kHz ("low") signals and 0.02- to 0.3-s, 32- to 64-kHz ("high") signals. A considerable repertoire of frequency modulated signals was observed and proved to be sensitive to the anxiolytic treatments. Diazepam (1-6 mg/kg) dose-dependently decreased high frequency USV during the threat of attack and decreased the mean pitch of the most predominant vocalizations but did not affect low frequency USV or the audible squeals (AS) in response to bites. Gepirone (0.3-6 mg/kg) dose-dependently decreased low frequency USV and did not affect high frequency USV or AS. Responses to thermal pain stimuli remained unaltered by all drugs, while walking duration was decreased and crouch postures were increased after diazepam but not after gepirone administration. Gepirone in the present dose range had minimal effects on submissive, exploratory and locomotor behaviors. The pattern of results is consistent with the proposal that low frequency USV reflect a heightened affective state which is ameliorated with 5HT1A but not benzodiazepine anxiolytics, and suggests that the suppression of high frequency USV in reaction to attacks or threats coincides with the sedative or muscle relaxant properties of these compounds.

Morphine attenuates ultrasonic vocalization during agonistic encounters in adult male rats.

Ultrasonic vocalizations (USV) in rats may communicate "affective" states during pain, sex and aggression. This proposal was evaluated in an experiment with adult male Long-Evans rats during agonistic encounters; specifically, morphine and naltrexone effects were studied on different types of USV by intruder rats exposed to resident attacks and to "threat of attacks" (i.e., intruder residing within the home cage of the resident but prevented from physical contact by a wire mesh cage). Intruders readily emitted USV during agonistic encounters. These calls consisted primarily of two distinct distributions of pure tone whistles: 0.3-3 s, 19-32 kHz ("low") calls and 0.02-0.3 s, 32-64 kHz ("high") calls. Sonographic analysis revealed a considerable repertoire of frequency modulated calls. Different types of vocalizations proved to be differentially sensitive to the opiate treatments: morphine (1-10 mg/kg SC) dose-dependently decreased the rate, duration and pitch of both low and high frequency USV during the threat of attack; this decrease in rate and duration measures was naltrexone-reversible (0.1 mg/kg IP). Interestingly, audible vocalizations were also emitted but were unaffected by morphine in this dose range. Concomitant with the decrease in USV after morphine was a dose-dependent decrease in rearing, walking and nasal contact behavior with increases in submissive crouch behavior and tail flick analgesia. The decreases in rate and duration of both low and high USV and the pitch of specific frequency modulated calls after morphine administration may reflect an attenuation of affective aspects of pain, and the many characteristics of US (rate, duration, pitch, frequency modulation, pre-and suffix attributes and temporal structure) point to potentially diverse functions.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of cage trapping for rabbit control on a Scottish hill farm

Rabbits were caught in wire mesh cage traps baited with carrot in a 10 ha field on a Scottish hill farm. The area used by the rabbits coming into the field was determined by the location of radio-collared individuals. In March the field was trapped out for 8 nights. The sample of rabbits obtained was analysed for sex, age, body and breeding condition to see if trapping was selecting part of the population. It was found that there was a bias towards males and non-pregnant females: of 185 rabbits caught in 32 traps, 62% were males. Assuming a 1:1 sex ratio in the population, the density of adult rabbits was estimated to be 15.9 ha −1. The results are discussed in relation to the potential effectiveness of cage trapping for rabbit control.

Ultrasounds during agonistic interactions between female rats (Rattus norvegicus).

Defensive and vocal behaviors of 18 female Long-Evans rats (Rattus norvegicus) in encounters with aggressive, lactating conspecifics were examined in order to determine if female rats emit ultrasounds during agonistic interactions and to characterize any such calls. The subjects, selected during estrus or diestrus, were exposed to 1-min attacks at 25-min intervals. Between attacks the subjects were threatened by the aggressor but protected by a wire-mesh cage. Female rats emitted both high- (32-60 kHz) and low-frequency (20-32 kHz) ultrasonic calls in agonistic encounters, with the rate of high-frequency calls enhanced during estrus. Low-frequency ultrasounds were shorter in duration and higher in frequency than those emitted by male rats in similar conditions. We conclude that female rats emit ultrasonic calls during defensive responding and that the characteristics and rate of calling vary as functions of sex and gonadal hormone state.

Hand-Reared Loggerhead Shrikes Breed in Captivity

Many continental populations of the Loggerhead Shrike (Lanius ludovicianus) have been declining in abundance for a number of years (Robbins et al. 1986, Brooks and Temple 1990, Lowe and Butcher 1990), and the San Clemente Island subspecies (L. 1. mearnsi) in California is highly endangered (Scott and Morrison 1990). Consequently, biologists have become increasingly interested in using manipulative techniques to study factors underlying the decline and to augment or restore wild populations. These techniques include the release of captive-raised and captive-bred shrikes, the translocation of adults, their eggs and young, and related manipulations (Kuehler et al., in press). It seems worthwhile, therefore, to report some details on the successful breeding of this species in captivity in 1971, especially as the loggerhead has not previously bred in captivity, and the few successful attempts with Eurasian species (L. collurio, L. excubitor, L. schach, and L. vittatus) have, with one exception (Giinther 1904), involved wild-caught, adult pairs (England 1970, 197 la, 1971b; Weischner 1989). The breeding pair of loggerheads came from a group of eight young shrikes taken from nests in northeastern Colorado in June, 1970, and hand-reared from the age of 8-9 days. These shrikes were transported to Dryden, New York as nestlings and were kept together until late September, when increasing aggression necessitated separation. During this period the birds were trained (Cade 1962, 1967) and allowed daily flights outside their cage as part of a study of the development of their hunting and impaling behavior. During fall and winter, individuals were housed indoors in separate, wire-mesh cages measuring 1.2 m in each dimension. The cages were arranged so that all the birds could see and hear each other. Five birds contracted avian pox and died during the winter; the three survivors were two males and a female. In mid-April, 1971 one of the male shrikes began a daily routine of singing and displaying in an extreme upright posture, leaning somewhat backward with its beak pointed straight up, and often turning slowly to one side or the other in this extreme upright posture while quivering its wings and singing. The behavior appeared identical to that of captive Northern Shrikes (Lanius excubitor) observed previously (Cade 1962). On 19 April, this bird was transferred to the Behavioral Ecology Building (Hawk Barn) at the Cornell University Laboratory of Omrnithology and placed in a chamber measuring 3 m wide by 6 m long and varying from 4.2-6 m high. The room had been provided with several freshly cut, leafless willow (Salix sp.) shrubs and hawthorns (Crataegus sp.) ranging from 2-3 m high to simulate a natural environment. Some branchlets were broken and sharpened to provide convenient impaling devices. Throughout the breeding season, laboratory mice, nestling sparrows and starlings, and dayold cockerels were provided for food. In addition, some insects (beetles, wasps, flies) entered the room from an open, wired front and were eaten. Later, an old but well-formed nest of the Brown Thrasher (Toxostoma rufum) was affixed 1.5 m up against the trunk of a hawthorn, and twigs, dry grass, cotton tufts, and wool yarn were placed on the floor for nesting materials. In a few days, the male appeared at ease in his new chamber, singing and displaying from several prominent perches. On 27 April, the female shrike was let loose in the chamber. She perched low in the middle of a hawthorn and did not move. The male flew down and hopped all around in branches near her. She did not flee, vocalize, or attempt to fight but sat still in a I Received 13 April 1992. Accepted 27 July 1992. SHORT COMMUNICATIONS 1027

Changes in male copulatory behavior after sexual exciting stimuli: Effects of medial amygdala lesions

A paradigm was developed to investigate how precoital sexual arousal affects parameters of sexual behavior in male rats. Estrous females in a wire mesh cage were used to induce sexual arousal before the sexual interaction test. In control procedures, males were presented in a wire mesh cage or else there was no stimuli at all. The results indicate that ejaculation latency is consistently reduced after preexposure to a female, but not after preexposure to a male, showing that the effect is specific for precoital sexual arousal. Other parameters were affected by precoital sexual arousal in some, but not in all experiments. Reductions in intromission latency moreover, were observed after both preexposure to a male and preexposure to a female, indicating that general social excitement affects this parameter. Preexposure to females for 10 minutes or 3 hours produced similar results. It was subsequently found that medial amygdala-lesioned (AME) animals differed from sham-lesioned (SHAM) controls with respect to their reaction to precoital sexual arousal. The results show that AME-lesioned animals, in contrast to SHAM-animals, do not show reduced ejaculation latencies after preexposure to an estrous female. The results are in line with the idea that AME-lesioned animals are deficient in the assimilation of information on sexual exciting stimuli.

INFLUENCE OF CULTURE ON FRESH-MARKET TOMATO PRODUCTION COSTS

Fresh market tomato cultivar and cultural trials are conducted yearly at the Oklahoma Vegetable Research Station near Tulsa. From 14 to 18 cultivars have been evaluated each season since 1985 comparing the Florida stake-and-weave and the wire mesh cage cultural systems. Results from 7 years of trials indicate caging produced 32% greater marketable yield than the stake-and-weave system. Percentage early yield was reduced with the cage system. Percentage of cull fruit was greater with the stake-and-weave system due to a higher incidence of fruit cracking. Average fruit size was not affected by cultural system. Cost of production analysis showed a lower cost of production with the cage system. The cage system is more capital intensive and the stake-and-weave system is more labor intensive. Undesirable factors in the use of cages are greater difficulty in picking the early fruit clusters, logistics in off-season storage of cages and the larger capital investment required for the cage system.

Health risks of housing small psittacines in galvanized wire mesh cages

Summary Each week over a 6-week period, 80 adult cockatiels (Nymphicus hollandicus) of either gender were dosed orally with fine particles of pure zinc or galvanized coating removed from welded wire mesh. At dosage of 32 mg/wk, all birds became severely ill and either died or were euthanatized within 2 weeks. Dosage of 2 mg/wk induced chronic illness marked by dullness, weight loss, and intermittent excretion of greenish droppings. Necropsy findings were unremarkable, except for signs suggestive of impaired gastrointestinal tract motility and histologic degenerative changes associated with focal mononuclear infiltration in the liver, kidneys, and pancreas. Tissue, especially pancreatic, contents of zinc were markedly high. Pure zinc was as toxic as galvanizing zinc. White rust, an oxidation product, also was toxic. The galvanized coating on cages and flights must be carefully wire-brushed and examined before housing psittacine birds.

Flow support catheter for prolonged maintenance of coronary blood flow

A newly designed flow support catheter with a supporting wire mesh cage which can be expanded into a tubular configuration and then readily reduced was evaluated in mongrel dogs. Regional myocardial blood flow (RMBF) was measured using the radioactive microsphere technique in the area of both balloon-denuded instrumented and control non-instrumented coronary arteries following placement of either a fixed-wire or a higher profile rapid exchange flow support catheter. At 5, 20, and 180 min following delivery and expansion of either device, RMBF was not significantly different in left ventricular subepicardium and subendocardium perfused by the instrumented vs. the control coronary arteries. Angiography demonstrated widely patent instrumented arteries in 15/18 dogs; in no dog was side branch occlusion observed. Significant cage thrombus deposition was seen angiographically in 3 animals causing temporary total coronary occlusion in 1. Following reduction and removal of the flow support catheter, vessel patency was present in all dogs. The flow support catheter is an effective endovascular stenting device capable of providing structural arterial support, while simultaneously maintaining distal coronary blood flow. It is envisioned that the primary application of this catheter will be to enable primary salvage of vessels acutely injured during coronary angioplasty, by "tacking up" intimal flaps for an extended period. It may also provide a bridge to emergency surgical revascularization.

Effect of Introduced Scarab Beetles (Coleoptera: Scarabaeinae) on Coprophilic Insects in Central Queensland

The effect of scarab beetle activity on the breeding of coprophilic insects in cattle dung was investigated in a pasture in central Queensland. On seven occasions, natural dung pats were covered with one of two types of wire mesh cages: fine mesh was used to exclude scarabs, and coarse mesh protected an equal number of other pats from trampling by cattle. Pats under the coarse mesh were colonized by the usual range of dung arthropod fauna including scarabs. Populations of scarabs and other dung arthropods also were sampled on each occasion using pitfall traps baited with cattle dung. Fewer adult predaceous insects were collected from pats beneath the coarse mesh. These pats also yielded fewer Diptera, hymenopterous parasitoids, and coprophagous Coleoptera than the pats beneath the fine mesh.

A study of the use of resting platforms by farmbred blue foxes

There are general demands and recommendations drafted by animal welfare organizations that a resting platform with a solid surface be provided for farmbred foxes kept in wire-mesh cages. The aim of the present study was to evaluate whether or not blue foxes themselves prefer to use the platforms and to determine the underlying factors affecting their use. Data were collected by direct visual observation combined with automatic sampling on a total of 47 blue foxes for 120 24-h days altogether. The animals included individuals of both sexes and both yearlings and older foxes. The platforms, forming a shelf inside the cages, were mounted in place in summer or autumn, and their use was observed up to late winter. All foxes used the platforms. They spent an average of 6.8±1% of their daily time or 98±15 min day −1 on the platform. A major portion of the use comprised visits of short duration. The platforms were used more during the working day, when short visits were also most common, than during the evening/night hours. Open platforms were used more than platforms with walls (150 vs. 19 min). The interest the animals showed in the platforms decreased with time. Unexpectedly, the platforms were used more at or above freezing temperatures than during really cold weather (120 vs. 67 min). Wind alone did not increase platform use, but high wind combined with high temperature promoted use. Inter-individual differences contributed to 59% of the variance of use, followed by the type of platform (walls vs. no walls) (17%) and temperature (5%). The effects of sex and orientation of the platforms with respect to the sun were not significant. The results do not support the hypothesis that the platforms function as shelter, rather the platforms were used because they were available. Because of large inter-individual variation in the preference for platforms, this trait can be increased easily through selection, provided that future experiments can confirm the beneficial effect of the platforms on the animals' welfare.

Mate detection success of maleClethrionomys rufocanus in relation to the spatial distribution of sexually receptive females

Mate detection success of male grey-sided voles,Clethrionomys rufocanus, in relation to the spatial distribution of sexually receptive females was studied in an experimental island population. The spatiotemporal distribution of receptive females was controlled by containing females in small, mobile wire-mesh cages, whereas the response by free-ranging males was monitored by means of radiotelemetry. Males were on average more successful in finding oestrous females when females were spatially clumped than when females were spatially overdispersed. In addition, the variance (CV) in male mate detecting success was highest when females had an overdispersed spatial distribution. These results are consistent with predictions from a theoretical model (Ims, 1988b) analysing the effect of mate distribution on male mating success, and with empirical results on prey detection success of predators searching for prey.

Field Urine Concentration in Two Indian Desert Gerbils

One of the most striking physiological features of many desert-dwelling rodents is the ability to produce concentrated urine. Several investigators (MacMillen, 1972; MacMillen and Christopher, 1975; MacMillen and Grubbs, 1976) reported urine concentrations of noncaptive desert heteromyid rodents, but comparable data generally are not available for rodents from other deserts. Herein, I provide information on urine concentrations of two Indian desert gerbil species, Meriones hurrianae and Tatera indica, in their natural habitats. Meriones hurrianae (body mass range, 56-70 g) and T. indica (body mass range, 80-120 g) are the most abundant and desert-specialized rodent species of the Indian desert (24-30.5*N, 70*-76.2*E). Animals were captured in Sherman live traps baited with peanut butter during several months. Immediately after capture, animals were brought to the animal house at the Central Arid Zone Research Institute at Jodhpur (26*10'N, 7301'E) and housed individually in wire-mesh cages for collecting urine over the next 24 h. For T. indica, traps were set late at night. Captured animals were moved to the animal house early in the morning and kept in cages for the collection of urine. The crepuscular M. hurrianae was removed from traps within 1 h of capture and placed in cages. During urine collection, animals were provided with pearled millet (Pennisetum typhoides) ad lib. but no drinking water. Simultaneously with studies on freshly captured animals, laboratory-acclimatized animals of both species were provided with pearled millet and water ad lib., and urine samples were collected over a 24-h period. Urine samples were collected by placing a large petri dish with a layer of mineral oil under each cage. Urine was pipetted into plastic vials and stored frozen in capped vials under a layer of mineral oil. Urine osmolarity was measured using a Precision Osmette 'A' milliosmometer. Necessary dilutions were made with ,l pipettes. Each urine sample was measured at least twice and the mean value used for comparisons. Meriones hurrianae usually had lower urine osmolarity than T. indica (Fig. 1), although values differed significantly (P < 0.01) only during July. During the monsoon period (July), urine osmolarity was reduced from respective summer (May) values by 52% in M. hurrianae and by 29% in T. indica, presumably reflecting reduced need for water conservation during the monsoon. During summer, a mean urine osmolarity of 3,180 mOsm/l in M. hurrianae (maximum value, 4,645 mOsm/1) and a mean of 5,128 mOsm/l in T. indica (maximum value 7,547 mOsm/1) were recorded. Mean urine osmolarities in summer did not differ significantly between species. During November and December, urine osmolarity values for freshly captured animals of both species were similar to values for laboratory-acclimatized, hydrated conspecifics. Freshly captured T. indica excreted more concentrated urine in most months than laboratory-acclimatized, hydrated conspecifics. This suggests that the natural milieu of this species is more water-stressful than laboratory conditions. In their natural environment, these animals encounter the need to conserve body water, and likely do so through their powerful kidneys. Purohit and Ghosh (1963) reported that Tatera indica possesses longer kidney papillae than M. hurrianae. T. indica consumes large quantities of insects (Prakash, 1975), and the qualitative pattern of their urine osmotic concentration in the field is similar to that reported by MacMillen (1972) for the carnivorous-insectivorous Onychomys torridus that also exhibits fairly high and seasonally uniform urine concentration. Urine of freshly captured M. hurrianae had either similar or lower concentration than that from laboratoryacclimatized, hydrated conspecifics. This pattern suggests that these crepuscular rodents are not water stressed in the field, even in summer. This state of hydration is attributed to the high water content of their diet of roots and rhizomes. In the view of MacMillen and co-workers (MacMillen and Grubbs, 1976; MacMillen and Hinds, 1983), the relationship between metabolic-water production, evaporative-water loss, and ambient temperature ultimately determines the extent of urine concentration; at low temperatures, metabolic-water production is high relative to evaporative-water loss, water balance is accordingly favorable, and there is reduced need to produce highly concentrated urine. These workers reported that during nocturnal surface activity in the warmer summer months, desert heteromyid rodents frequently encounter temperatures exceeding that at

Effects on Productivity and Aggressive Behavior of Laying Hens of Solid Versus Wire Cage Partitions and Bird Density

The effects of solid metal cage partitions or wire mesh cage partitions and two cage densities (5 or 7 birds/60.9 cm × 35.6-cm shallow cage) on production performance traits, aggressive behavior, and feather covering of White Leghorn layers were assessed from 20 to 60 wk of age. Type of cage partition had no significant effects on any of the traits measured. Higher cage density, however, was associated with significantly lower hen-day egg production, feed usage, final body weights, and feather covering. No differences were observed for egg weights, egg loss, mortality, or aggressive head pecking activity of birds housed in the two cage densities.

Inhalation Exposure System Used for Acute and Repeated-Dose Methyl Isocyanate Exposures of Laboratory Animals

Laboratory animals were exposed by inhalation for 2 hr/day (acute) or 6 hr/day (four consecutive days, repeated dose) to methyl isocyanate (MIC). Exposures were conducted in stainless steel and glass inhalation exposure chambers placed in stainless steel, wire mesh cages. MIC was delivered with nitrogen via stainless steel and Teflon supply lines. Chamber concentrations ranged from 0 to 60 ppm and were monitored continuously with infrared spectrophotometers to 1 ppm and at 2-hr intervals to 20 ppb with a high performance liquid chromatograph equipped with a fluorescence detector. Other operational parameters monitored on a continuous basis included chamber temperature (20-27 degrees C), relative humidity (31-64%), static (transmural) pressure (-0.3 in.), and flow (300-500 L/min). The computer-assistance system interfaced with the inhalation exposure laboratory is described in detail, including the analytical instrumentation calibration system used throughout this investigation.

Inhalation exposure system used for acute and repeated-dose methyl isocyanate exposures of laboratory animals.

Laboratory animals were exposed by inhalation for 2 hr/day (acute) or 6 hr/day (four consecutive days, repeated dose) to methyl isocyanate (MIC). Exposures were conducted in stainless steel and glass inhalation exposure chambers placed in stainless steel, wire mesh cages. MIC was delivered with nitrogen via stainless steel and Teflon supply lines. Chamber concentrations ranged from 0 to 60 ppm and were monitored continuously with infrared spectrophotometers to 1 ppm and at 2-hr intervals to 20 ppb with a high performance liquid chromatograph equipped with a fluorescence detector. Other operational parameters monitored on a continuous basis included chamber temperature (20-27 degrees C), relative humidity (31-64%), static (transmural) pressure (-0.3 in.), and flow (300-500 L/min). The computer-assistance system interfaced with the inhalation exposure laboratory is described in detail, including the analytical instrumentation calibration system used throughout this investigation.

Enrichment versus exercise effects on motor impairments following cortical removals in rats

Groups of rats were exposed to an enriched environment, given access to an activity wheel, or individually housed in wire mesh cages, impoverished. Rats were exposed in groups of four to the enriched environment or placed individually in the activity wheel for 2 h per day for 25 days preoperatively. Within each exposure group, rats sustained bilateral removals of sensorimotor cortex, or were sham-operated controls. Animals were trained preoperatively to locomote across a narrow elevated runway. Postoperatively, locomotor testing was initiated 17 days after surgery throughout which time all animals were maintained under impoverished conditions. Locomotor deficits following cortical damage were a function of preoperative exposure: enriched rats were least impaired; impoverished rats were most impaired. Rats allowed running wheel activity initially showed the same marked deficits as impoverished animals but recovered more rapidly. The opportunity for physical exercise afforded wheel animals preoperatively may have enhanced motor capabilities that aided recovery. However, physical activity alone did not yield the same protective effects from initial impairment as enrichment. Greater elaboration of neural structures associated with perceptual-motor enrichment probably accounted for the initial sparing of the enriched group.

Galef’s Transfer-of-Information Effect Occurs in a Free-Foraging Situation

Galef and his colleagues have repeatedly shown that one rat may transfer information regarding the type of food it has consumed to other conspecifics. Such experiments typically have been conducted in wire-mesh cages or a wooden maze. The present experiments sought to extend this paradigm to the open-field foraging situation having six food patches to choose from. Following interaction with a demonstrator that had consumed either a cocoa or a cinnamon diet, single observers (Experiment 1) were tested in the foraging situation. Food-consumption scores indicated that observers consumed significantly more of their specific demonstrator’s diet than a second diet that was available also. Experiment 2 involved the simultaneous testing of two observers in the foraging laboratory. In Experiment 3 two observers were once again tested, but each had been provided a different food-type message prior to foraging. Positive results, mirroring those of Experiment 1, were obtained in both Experiments 2 and 3. The results of these three experiments underscore the robustness of this phenomenon and its generalizability to other testing conditions.