Successive negative contrast in one-way avoidance learning in rats

In three experiments, successive negative contrast was examined in one-way avoidance learning. Reward magnitude in first (pre-shift) and second (post-shift) phases was manipulated by time spent in the safe compartment. Experiment 1 demonstrated that when time in the danger compartment was held constant, a group shifted from a large reward--30 sec spent in the safe compartment--to a small reward--1 sec--showed poor performance and longer response latency than a group conditioned with the small reward in both phases. Experiment 2 replicated this effect with a less intense shock and also demonstrated that a group shifted from large to small reward performed more poorly than a group exposed to large reward--30 sec--in both phases. Finally, Experiment 3 showed that changes in intertrial interval, defined as total time spent in the safe compartment and the danger compartment before the onset of the warning signal, were not responsible for this contrast effect. These results suggest that time spent in a safe place can act as appetitive incentive during one-way avoidance learning.     

Infantile handling and sex as determinants of the negative reinforcing effects of gentling

Summary BD IX rats were trained to avoid a black and white compartment which was associated with gentling. The rats were given 12 acquisition sessions in which they were stroked if they remained in the critical compartment at the end of the fifteen 20-sec intervals during the 5-min test period. The results indicated that the negative reinforcing effects of gentling were a function of the early handling history and sex of the rat.This research was aided by Grant APA-247 from the National Research Council of Canada. The author thanks David Wood for his active collaboration in conducting the experiment.     

The overshadowing of background stimuli: Some effects of varying amounts of training and ucs intensity

Two experiments investigated the capacity of a nominal CS to overshadow background stimuli. Rats received CS-shock pairings in one compartment of a double compartment apparatus. After training the shock compartment was represented, but in the absence of both the CS and shock. Overshadowing was then assessed by measuring rats' latency to enter this compartment. If rats readily entered the shock compartment this indicated that the background cues in that compartment had acquired little or no associative strength during training, and overshadowing was therefore inferred. If however rats avoided the shock compartment, then this indicated that the background stimuli must have become aversive during training, and overshadowing could not then be inferred. In both experiments it was found that the capacity of a CS to overshadow background stimuli was directly related to the amount of training given. The experiments also showed that this capacity is inversely related to shock intensity. The results are discussed in terms of Rescorla and Wagner's (1972) model of conditioning.     

Asymmetrical transfer of braille acquisition between hands

Two experiments are presented which demonstrate asymmetrical transfer for tactual recognition of individual braille letters in sighted subjects, a task usually associated with right hemisphere specialization. Right-handers were studied in Experiment 1, left- and right-handers in Experiment 2. Poor transfer of training from the right hand to the left hand was observed for right-handed subjects in both experiments. The same was true for one group of left-handers (who wrote with the "inverted" position). For another group (who wrote with the "noninverted" position), no disadvantage was associated with opposite-hand training for either hand. The role of hemispheric specialization of function in determining the direction of greater transfer is discussed, and it is argued that handwriting posture may be an index of the degree of functional "connectedness" of the two hemispheres in left-handers.     

An assessment of the role of handling cues in "spontaneous recovery" after extinction

Three experiments examined the assertion that presession handling cues that accompany training with reinforcement might account for spontaneous recovery when they reoccur following extinction. In Experiment 1, after extensive training on a variable-interval schedule, key pecking in pigeons was extinguished following either normal or distinctively different handling and transportational cues. Those cues resulted in enhanced spontaneous recovery 24 hr later when normal cues were reinstated. In Experiment 2, however, subjects tested following the normal handling cues showed no more spontaneous recovery than did subjects that spent the entire extinction-test interval in the experimental chambers and thus were tested without handling cues altogether. In Experiment 3, a group whose test for recovery began 10 min after being placed in the chambers yielded as much spontaneous recovery as did a group tested normally. Furthermore, a group for which extinction began at mid-session and for which handling therefore could not be a discriminative cue for extinction showed no more spontaneous recovery than did the other two groups. Handling cues thus contributed to spontaneous recovery only after explicit discrimination training, as provided in Experiment 1.     

Stress in cynomolgus monkeys (Macaca fascicularis) subjected to long-distance transport and simulated transport housing conditions

The stress associated with transportation of non-human primates used in scientific research is an important but almost unexplored part of laboratory animal husbandry. The procedures and routines concerning transport are not only important for the animals' physical health but also for their mental health as well. The transport stress in cynomolgus monkeys (Macaca fascicularis) was studied in two experiments. In Experiment 1, 25 adult female cynomolgus monkeys were divided into five groups of five animals each that received different diets during the transport phase of the experiment. All animals were transported in conventional single animal transport cages with no visual or tactile contact with conspecifics. The animals were transported by lorry for 24 h at ambient temperatures ranging between 20 degrees C and 35 degrees C. Urine produced before, during and after transport was collected and analysed for cortisol by enzyme-linked immunosorbent assay (ELISA). All monkeys exhibited a significant increase in cortisol excretion per time unit during the transport and on the first day following transport.Although anecdotal reports concerning diet during transport, including the provision of fruits and/or a tranquiliser, was thought likely to influence stress responses, these were not corrobated by the present study. In Experiment 2, behavioural data were collected from 18 cynomolgus macaques before and after transfer from group cages to either single or pair housing, and also before and after a simulated transport, in which the animals were housed in transport cages. The single housed monkeys were confined to single transport cages and the pair housed monkeys were kept in their pairs in double size cages. Both pair housed and singly housed monkeys showed clear behavioural signs of stress soon after their transfer out of their group cages.However, stress-associated behaviours were more prevalent in singly housed animals than in pair housed animals, and these behaviours persisted for a longer time after the simulated transport housing event than in the pair housed monkeys. Our data confirm that the transport of cynomolgus monkeys is stressful and suggest that it would be beneficial for the cynomolgus monkeys to be housed and transported in compatible pairs from the time they leave their group cages at the source country breeding facility until they arrive at their final laboratory destination in the country of use.     

Learning-induced arg 3.1/arc mRNA expression in the mouse brain

The effector immediate-early gene (IEG) arg 3.1, also called arc, encodes a protein interacting with the neuronal cytoskeleton. The selective localization of arg 3.1/arc mRNA in activated dendritic segments suggests that the arg 3.1/arc protein may be synthesized at activated post-synaptic sites and that arg 3.1/arc could participate in structural and functional modifications underlying cognitive processes like memory formation. To analyze whether learning itself is sufficient to trigger expression of arg 3.1/arc, we developed a one-trial learning paradigm in which mice learned to enter a dark compartment to escape from an aversively illuminated area. Arg 3.1/arc mRNA expression was analyzed by in situ hybridization in three groups of mice as follows: a control group with no access to the dark compartment, a learning group having access to the dark compartment for one trial, and a retrieval group having access to the dark compartment for two trials on consecutive days. All animals from the learning and retrieval groups escaped the illuminated area, and those tested 24 h later (retrieval group) showed a strongly reduced latency to enter the dark compartment, demonstrating the validity of our learning paradigm to induce long-term memory. Our results show that acquisition of a simple task results in a brain area-specific biphasic increase in arg 3.1/arc mRNA expression 15 min and 4.5 h post-training. This increase was detected specifically in the learning group but neither in the control nor in the retrieval groups. The pattern of arg 3.1/arc mRNA expression corresponds temporally to the two mRNA- and protein-synthesis-dependent periods of long-term memory formation. Our study provides the first unequivocal evidence that arg 3.1/arc expression is induced by a learning task and strongly suggests a role of arg 3.1/arc mRNA in the early and late cellular mechanisms underlying the stabilization of the memory trace.     

Asymmetrical transfer of training between hands: implications for interhemispheric communication in normal brain

Two experiments are presented which investigated claims of asymmetrical transfer of training between the hands/hemispheres. In Experiment 1, 96 right- and left-handed male undergraduates practiced an inverted-reversed printing task with either the right or the left hand. Transfer to the opposite hand was then compared to same-hand transfer, in a between-subject design. In Experiment 2, 176 right-handed boys and girls were tested at ages 7, 9, and 11 years. For right-handed subjects in both experiments, the left hand benefited more from opposite-hand training than did the right. The reverse was true for left-handers in Experiment 1, although one group (who wrote with the "inverted" position) showed little transfer in either direction. Two current models of interhemispheric interaction do not satisfactorily explain these findings. A third model, based on cross-activation, may provide a more effective alternative.     

Rubber hands feel the touch of light

Two experiments involving a total of 220 subjects are reported. The experiments document that "stroking" a false hand with the bright beam of light from a laser pointer can produce tactile and thermal sensations when the hand can be seen as one's own. Overall, 66% of subjects reported somatic sensations from the light. Felt hand location was recalibrated toward the location of the false hand for those subjects who felt the light. Moreover, the proprioceptive recalibration from the laser experience was comparable to that produced by actual coordinated brushing of the false hand and of the unseen real hand after 2 min of stimulation. The illusion may be experienced on one's real hand as well. The results are discussed in terms of multisensory integration.     

Phonological Processing and Right Minus Left Hand Skill

Two experiments tested the hypothesis that children at the left of the distribution of right minus left (R-L) hand skill are at risk for poor phonological processing. In the first experiment, individual assessments of spoken rhyme awareness were made in 5- to 8-year-olds. In the second experiment, a group test of word order memory for spoken confusable and nonconfusable items was given to 9- to 11-year-olds. Evidence of poorer phonological processing in those at the left of the R-L distribution was found in both experiments. Rhyme judgements and word order memory were both associated with reading ability, but reading did not interact with effects for hand skill. A group test of homophone comprehension was given to the same children tested for word order memory. Homophone errors did not differ between hand skill groups, showing a dissociation between the two tasks for R-L hand difference. The findings suggest that some risks for phonological processing could be due to normal genetic variation associated with the hypothesized rs + gene (Annett, 1972, 1978).     

Spatial reference and scanning with the left and right hand

Discrepant findings on performance by the two hands in spatial tasks make it difficult to infer spatial coding unambiguously. We tested the hypotheses (a) that the left hand is consistently better in haptic spatial tasks and (b) that adding spatial reference information produces more accurate coding in spatial tasks, independently task and hand effects. Instructions to use external cues from a surrounding frame as well as body-centred cues for reference produced highly significant increases in accuracy in haptic distance and location experiments. The distance experiments showed no hand differences. A small right-hand advantage with longer positioning movements in the recall of locations was significant when combined with left-hand scanning of the frame, but did not relate to reference conditions. Hand use interacted significantly with the location-versus-distance experiments, but showed no interaction with the spatial reference factor, which was highly significant in both experiments. The finding suggests that modes of coding need to be distinguished from cross-lateral effects of sensory input conditions. The study shows that varying reference information offers a potentially useful behavioural tool for distinguishing spatial coding from input and task conditions independently of hand performance. Methodological, practical, and theoretical implications are discussed.     

A comparison of simulated one-way and shuttle avoidance in an automated apparatus

The fully automated shuttle box employed in two experiments permitted the comparison within one apparatus of performance under a simulated one-way condition and the usual shuttle condition. Animals in the simulated one-way condition always ran from a white compartment into a black compartment, but alternated their direction of locomotion, as did the shuttle animals. In both experiments, animals run under the simulated one-way condition showed superior per cent avoidance performance relative to the shuttle animals. The results were compared with those obtained in other one-way avoidance and shuttle studies.     

Successive positive contrast in one-way avoidance learning

The main finding of these experiments was a positive contrast effect in one-way avoidance learning. Experiment 1 showed that increasing safety time during one-way avoidance training led to improved performance, surpassing that of a control group that had received the high reward (safe time) from the beginning of training. Experiment 2 showed that a similar positive contrast effect occurred when the time spent in the danger compartment before the onset of the warning signal was shortened. These results suggest that time spent in a safe context acts as a reinforcer of the avoidance response; however, its incentive value depends not only on its duration, but also on the length of the time spent in the danger compartment before the onset of the signal. Overall, results also suggest that the avoidance response is a mixture of flight (motivated by fear) and approach (to a safe place) behaviour. The specific weight of the flight or approach component may be a function of the time and the amount of activation of each emotional state (fear or relief) due to opponent homeostatic compensatory processes that occur in the danger and safe compartments during one-way avoidance learning.     

The situational effects on haptic perception of rod length

Three experiments were conducted to investigate situational effects (manipulation, range, and prior experience) on the haptic perception of rod length. Each rod was held between its two ends with one hand. In Experiment 1, 32 participants judged length of rods using different manipulations. Perceived lengths were found to be dependent on manner of manipulation and not necessarily equal to actual lengths. Different parameters were detected in different manipulations. In Experiment 2, 8 participants judged rod lengths by wielding rods of two ranges: long and short. Perceived length was found to be affected by the range of rods evaluated successively in a single set. In Experiment 3, 9 participants judged rod lengths after an experience of handling dense or light rods. Perceived length was found to be affected by prior experience. Results are discussed in terms of how rod lengths can be perceived accurately by haptic modality without involving direct perception.     

Are monkeys able to plan for future exchange?

Whether or not non-human animals can plan for the future is a hotly debated issue. We investigate this question further and use a planning-to-exchange task to study future planning in the cooperative domain in two species of monkeys: the brown capuchin (Cebus apella) and the Tonkean macaque (Macaca tonkeana). The rationale required subjects to plan for a future opportunity to exchange tokens for food by collecting tokens several minutes in advance. Subjects who successfully planned for the exchange task were expected to select suitable tokens during a collection period (5/10?min), save them for a fixed period of time (20/30?min), then take them into an adjacent compartment and exchange them for food with an experimenter. Monkeys mostly failed to transport tokens when entering the testing compartment; hence, they do not seem able to plan for a future exchange with a human partner. Three subjects did however manage to solve the task several times, albeit at very low rates. They brought the correct version of three possible token types, but rarely transported more than one suitable token at a time. Given that the frequency of token manipulation predicted transport, success might have occurred by chance. This was not the case, however, since in most cases subjects were not already holding the token in their hands before they entered the testing compartment. Instead, these results may reflect subjects' strengths and weaknesses in their time-related comprehension of the task.     

An illusion you can sink your teeth into: haptic cues modulate the perceived freshness and crispness of pretzels

Eating is a multisensory experience involving more than simply the oral sensation of the taste and smell of foods. It has been shown that the way foods look, sound, and feel like in the mouth all affect food perception. The influence of haptic information available when handling food is relatively unknown. In this study, blindfolded participants bit-into fresh or stale pretzels while rating their freshness staleness and crispness-softness. Information provided to the hand was either congruent (whole pretzel fresh or stale) or incongruent (half pretzel fresh, half stale) with what was presented to the mouth. The results demonstrate that the perception of both freshness and crispness was systematically altered when incongruent information was provided: bit-into fresh pretzel tips were perceived as staler and softer when a stale pretzel tip was held in the hand and vice versa. Haptic information available when handling food thus plays a significant role in modulating food perception.     

An examination of the relationship between visual capture and prism adaptation

The phenomena of prismatically induced “visual capture” and adaptation of the hand were compared. In Experiment 1, it was demonstrated that when the subject’s hand was transported for him by the experimenter (passive movement) immediately preceding the measure of visual capture, the magnitude of the immediate shift in felt limb position (visual capture) was enhanced relative to when the subject moved the hand himself (active movement). In Experiment 2, where the dependent measure was adaptation of the prism-exposed hand, the opposite effect was produced by the active/passive manipulation. It appears, then, that different processes operate to produce visual capture and adaptation. It was speculated that visual capture represents an immediate weighting of visual over proprioceptive input as a result of the greater precision of vision and/or the subject’s tendency to direct his attention more heavily to this modality. In contrast, prism adaptation is probably a recalibration of felt limb position in the direction of vision, induced by the presence of a registered discordance between visual and proprioceptive inputs.     

The effects of mental imagery on skin temperature and skin temperature sensation

In a series of six experimental sessions five subjects were instructed to imagine their hand in a hot and cold water stream. During the imagery period the subjects estimated with a psychophysical scale their subjective temperature sensations caused by the imagery. Skin temperature was measured from the thumb of the subjects' dominant hand. After each session the subjects were asked whether they had succeeded in producing an imagery. The skin temperature changes deviated significantly from the control level in the successful imagery experiments. Differences in the skin temperature changes between the successful and unsuccessful imagery experiments were significant. The skin temperature changes measured and the subjects' temperature sensations, produced by the imagery, were similar in the successful imagery experiments. The possible relationships between mental imagery and changes in skin temperature and skin temperature sensation are discussed.     

食管癌切除术后颈部不同方法食管胃吻合比较分析

比较食管癌切除术后应用非一次性沪产吻合器和手工缝合在颈部行食管胃吻合的经验体会。我科1998年11月~2010年12月,食管癌切除术后应用沪产吻合器在颈部通过＂反插法＂进行食管胃吻合126例;手工缝合100例。结果全部病例均治愈出院,手工缝合组发生吻合口瘘5例,吻合口狭窄9例,食物返流18例,吻合口出血1例;吻合器组未...     

Preference for information about intensity of signaled tailshock

Three experiments are reported which were designed to demonstrate preference for signaled shock and to delineate the roles of the preparatory-response, information-seeking, and signaled-safety hypotheses of this phenomenon. Experiment 1 demonstrated a preference for a signal-tailshock condition over a tailshock-signal condition in a shuttlebox. In Experiment 3, rats were exposed to signaled tailshock of two intensities in both compartments of the shuttlebox, but in one compartment the signals provided information about the intensity of the impending tailshock, whereas in the other compartment the signals did not. The tailshock intensities were .6 and 1.3 mA for one group and .6 and 1.8 mA for a second group. Experiment 2 assured that even the smaller intensity difference was readily discriminable. For Group .6-1.8 a significant preference for the condition in which the signals predicted the intensity of the impending tailshocks was obtained, but no preference for either condition was found for Group .6-1.3. As signaled safety was equated in the two compartments of Experiment 3, the observed preference cannot be accounted for by the signaled-safety hypothesis. Information seeking cannot explain the lack of preference in Group .6-1.3 as the difference between those two intensities was proven discriminable in Experiment 2. Assuming that sufficient differences in shock intensity yield different preparatory responses, the present results are compatible with the preparatory-response hypothesis and suggest that preparatory responding plays a role in producing the preference for signaled shock.