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One-trial visual recognition in cats
Abstract
The ability of normal cats to perform delayed matching- and nonmatching-to-sample with trial-unique stimuli was investigated both in a modified Wisconsin General Testing Apparatus requiring manipulatory responses and in a Nencki-type testing room requiring locomotor responses. Cats trained in the WGTA learned the two tasks at about the same rate, on average, as that reported for monkeys. However, unlike monkeys, whose strong preference for novelty facilitates their learning of the nonmatching rule and retards their learning of the matching rule, the cats learned the two different rules at about the same rate, suggesting that cats do not share the monkey's strong preference for novelty. In contrast to their relatively rapid learning of the manipulatory versions of the two tasks, cats learned the locomotor versions only slowly or even failed to learn. Experimental analysis indicated that a major source of the cats' difficulty on these locomotor versions was interference from a strong tendency in the large testing room to use visuospatial strategies. Nevertheless, once the matching or nonmatching rule was learned at short delays, whether in the WGTA or the testing room, the cats performed at criterion levels without further training even at delays of 10 minutes, indicating that this species, like monkeys, has a highly developed long-term recognition memory ability.
... Without memory, learning fails to provide a long-term benefit to the animal. Investigations of memory in carnivores have found evidence of long-term memory in domestic cats and dogs (Fugazza et al. 2016;Fugazza and Miklósi 2014;Okujava et al. 2005), as well as episodic-like memory in dogs (Fugazza et al. 2016, but see Sluka et al. 2018). In other canids, Mahamane et al. (2014) found that coyotes fail to discriminate between quantities of food when relying on memory, instead attending to which quantities are placed first, or those on the side congruent with a side bias. ...
The field of animal cognition has advanced rapidly in the last 25 years. Through careful and creative studies of animals in captivity and in the wild, we have gained critical insights into the evolution of intelligence, the cognitive capacities of a diverse array of taxa, and the importance of ecological and social environments, as well as individual variation, in the expression of cognitive abilities. The field of animal cognition, however, is still being influenced by some historical tendencies. For example, primates and birds are still the majority of study species in the field of animal cognition. Studies of diverse taxa improve the generalizability of our results, are critical for testing evolutionary hypotheses, and open new paths for understanding cognition in species with vastly different morphologies. In this paper, we review the current state of knowledge of cognition in mammalian carnivores. We discuss the advantages of studying cognition in Carnivorans and the immense progress that has been made across many cognitive domains in both lab and field studies of carnivores. We also discuss the current constraints that are associated with studying carnivores. Finally, we explore new directions for future research in studies of carnivore cognition.
... Both cats and dogs reportedly remembered events that occurred many months ago. Dogs can recall memories from weeks ago (Demant et al., 2011), but as far as we are aware, the longest delay observed in cats has been minutes (Okujava et al., 2005;Takagi et al., 2017), although see Saito and Shinozuka (2013) for an example of long-term recognition in cats. Furthermore, the retention periods we were able to observe necessarily were limited to the duration in which participants had owned their pet. ...
The case for episodic memory in non-human animals has been intensely debated. Although a variety of paradigms have shown elements of episodic memory in non-human animals, research has focused on rodents, birds and primates, using standardized experimental designs, limiting the types of events that can be investigated. Using a novel survey methodology to address memories in everyday life, we conducted two studies asking a total of 375 dog and cat owners if their pet had ever remembered an event, and if so, to report on their pet’s memory of the event. In both studies, cats and dogs were reported to remember a variety of events, with only 20% of owners reporting that their pet had never remembered an event. The reported events were often temporally specific and were remembered when commonalities (particularly location) occurred between the current environment and the remembered event, analogous to retrieval of involuntary memories in humans.
... Thirty years have passed since the first publication that described the object novelty recognition memory test (ONRMT) designed for rats (Ennaceur and Delacour 1987), which was later adopted for mice (Messier 1997;Dodart et al., 1997), and then for other species (Thinus-Blanc et al., 1992;Diamond 1990;Bachevalier et al., 1993;Lorrio et al., 2007;Lucon-Xiccato and Dadda, 2014;Moustgaard et al., 2002;Okujava et al., 2005;Stö we et al., 2006;Visser et al., 2002;Wood-Gush and Vestergaard 1991). This handbook covers various topics that illustrate the usages and advances made with a memory test, which is based on animals' spontaneous exploratory activity and which exploits their natural preference for novelty. ...
Object novelty recognition is derived from the spontaneous preference demonstrated towards an object which has not been encountered in the past. This preference of a novel object is the result of the retrieval of stored representations from previous experience of other objects. The stored representation of an object may be constituted from the whole or limited encoded features; it may also comprise the context or some elements of the context in which the object was presented. In rodents, object novelty recognition has been mostly concerned with memory types and processes, and it is only recently that a limited number of research studies started looking at object perception and encoding processes. In this chapter, we will describe the evidence from animal and human literature regarding the object features, the complexity objects, and the similarity between the paired objects and the representation of the familiar object. We will also describe various factors that contribute to encoding and discrimination or recognition of objects. Among these factors are the amount of pretest habituation sessions, changes in locomotor activity and exploration, and changes that may occur from the use of single versus a pair of identical or different objects in the acquisition phase. As discussed in this chapter, the object novelty recognition test has its limitations, particularly regarding the study of object features and working memory which require strict control over the test parameters. This could be resolved with the development of automated visual object recognition tests, which takes into consideration rodents’ visual abilities and the consequences of these in the design of a discrimination and a delayed nonmatching-to-sample test apparatus.
... The NOR test has emerged as one of the most popular paradigms to assess memory in rats and other rodents, such as mice and hamsters [3,4,5,6], because it is quick to administer and relatively simple. Moreover, the NOR test represents a promising paradigm for comparative research [1] since it can be successfully adapted to very different mammalian and avian species, such as monkeys [7,8], dogs [9], cats [10], horses [11], ravens [12], and parrots [13]. ...
The novel object recognition (NOR) test is a widely-used paradigm to study learning and memory in rodents. NOR performance is typically measured as the preference to interact with a novel object over a familiar object based on spontaneous exploratory behaviour. In rats and mice, females usually have greater NOR ability than males. The NOR test is now available for a large number of species, including fish, but sex differences have not been properly tested outside of rodents. We compared male and female guppies (Poecilia reticulata) in a NOR test to study whether sex differences exist also for fish. We focused on sex differences in both performance and behaviour of guppies during the test. In our experiment, adult guppies expressed a preference for the novel object as most rodents and other species do. When we looked at sex differences, we found the two sexes showed a similar preference for the novel object over the familiar object, suggesting that male and female guppies have similar NOR performances. Analysis of behaviour revealed that males were more inclined to swim in the proximity of the two objects than females. Further, males explored the novel object at the beginning of the experiment while females did so afterwards. These two behavioural differences are possibly due to sex differences in exploration. Even though NOR performance is not different between male and female guppies, the behavioural sex differences we found could affect the results of the experiments and should be carefully considered when assessing fish memory with the NOR test.
... The novel object preference (NOP) test, classically referred to as the novel object recognition test, and the one-trial object recognition test is the most commonly used paradigm for testing this form of memory. The NOP test was initially developed for rats [16] and later adapted to mice [13] [40], monkeys [38] [74], dogs [9] horses [68] parrots [41], cats [48] and ravens [64]. The test typically consists of a familiarization phase where animals are exposed to two identical objects (Trial 1—T1). ...
The novel object recognition, or novel-object preference (NOP) test is employed to assess recognition memory in a variety of organisms. The subject is exposed to two identical objects, then after a delay, it is placed back in the original environment containing one of the original objects and a novel object. If the subject spends more time exploring one object, this can be interpreted as memory retention. To date, this test has not been fully explored in zebrafish (Danio rerio). Zebrafish possess recognition memory for simple 2- and 3-dimensional geometrical shapes, yet it is unknown if this translates to complex 3-dimensional objects. In this study we evaluated recognition memory in zebrafish using complex objects of different sizes. Contrary to rodents, zebrafish preferentially explored familiar over novel objects. Familiarity preference disappeared after delays of 5minutes. Leopard danios, another strain of Danio rerio, also preferred the familiar object after a 1minute delay. Object preference could be re-established in zebra danios by administration of nicotine tartrate salt (50mg/L) prior to stimuli presentation, suggesting a memory-enhancing effect of nicotine. Additionally, exploration biases were present only when the objects were of intermediate size (2×5cm). Our results demonstrate zebra and leopard danios have recognition memory, and that low nicotine doses can improve this memory type in zebra danios. However, exploration biases, from which memory is inferred, depend on object size. These findings suggest zebrafish ecology might influence object preference, as zebrafish neophobia could reflect natural anti-predatory behaviour.
... The long-term memory of cats appears to be highly developed, as demonstrated by use of delayed visual matching and non-matching to sample in which cats performed at criteria level (80 % in 100 consecutive trails) at delays up to 10 min (Okujava et al. 2005). Further research must be undertaken to disentangle additional factors, such as age, breed and lifetime experience, that may influence the working and long-term memory of cats. ...
The domestic cat (Felis silvestris catus) has shared an intertwined existence with humans for thousands of years, living on our city streets and in our homes. Yet, little scientific research has focused on the cognition of the domestic cat, especially in comparison with human's other companion, the domestic dog (Canis lupus familiaris). This review surveys the current status of several areas of cat cognition research including perception, object permanence, memory, physical causality, quantity and time discrimination, cats' sensitivity to human cues, vocal recognition and communication, attachment bonds, personality, and cognitive health. Although interest in cat cognition is growing, we still have a long way to go until we have an inclusive body of research on the subject. Therefore, this review also identifies areas where future research must be conducted. In addition to the scientific value of future work in this area, future research on cat cognition could have an important influence on the management and welfare of pet and free-roaming cats, leading to improved human-cat interactions.
... The one-trial memory test has been widely used in rodents such as rats, mice and hamsters (Steckler et al., 1998;Thinus-Blanc et al., 1992;Heyser and Chemero, 2012) as well as in several other species including humans (Squire et al., 1988), monkeys (Malkova and Mishkin, 2003;Zola et al., 2000), dogs (Callahan et al., 2000), cats (Okujava et al., 2005), horses (Visser et al., 2002), ravens (Stowe et al., 2006) and parrots (Mettke-Hofmann et al., 2002). ...
For many years, neurosurgeons and neurointerventionalists have been focused on the neurological functionality of the patients as a main measure assessing the effects of treatment of intracranial aneurysms. But, individual experience, sporadic series of patients operated in a delayed fashion, as well as the patients operated before an aneurysm rupture indicate a necessity for better neurological, psychological, and Quality Of Life (QOL) assessments because the Glasgow Outcome Scale and QOL scale have become inadequate in the face of everyday life challenges for many patients. But to develop and test reliability of new tools, we need to develop a better understanding of pathomechanism(s) of neurobehavioral changes after aneurismal subarachnoid hemorrhage (aSAH) and at this moment we are lacking proper experimental models. Fortunately, animal models that have been developed to investigate delayed cerebral vasospasm should help to examine neurobehavioral changes after aSAH. Therefore, albeit many limitations that must be kept in mind, a systematic research, especially using a nonhuman primate model, should continue to play a critical role in the understanding of cognitive and behavioral function after aSAH.
This chapter consists of five main parts. In the first one (I - Introduction) the role of cognitive memory in "becoming" of the complexly organized systems is briefly considered from the viewpoint of the general systems theory; the role of Georgian neurophysiologists in emphasizing cognitive aspects of memory role in animal behavior is underlined. In the second part (II - Nonspatial visual recognition memory) the existence of the "one-trial" nonspatial visual recognition memory in cats, as representatives of carnivores with poorly developed vision, is established; it is shown that analogously to primates and rodents in cats the so called rhinal cortex plays a major role in mediating this type of visual cognitive memory. The following part (III - Spatial visual recognition memory) is devoted to spatial visual "one-trial" memory in cats; it is shown that in cats, similarly to primates and rodents, parahippocampal cortex (with possible inclusion in this system of the subicular complex) is responsible for visuospatial memory. In the next to last part of this chapter (IV - Two subsystems of spatial visual memory - delayed response problem) two probable subsystems of visual spatial memory - egocentric and allocentric - are briefly reviewed in the classical delayed response context; it is shown that the first one depends on the prefrontal cortex, while the second one - on the parietal association region. The last part (V - Conclusion) emphasizes authors' persuasion that "mechanisms of recall" from the cognitive memory store might be studied most fruitfully just in the field of cognitive recognition memory because of its controlled nature in appropriate behavioral testing paradigms.
The role of cognitive memory in "becoming" of the complexly organized systems is briefly considered from the viewpoint of the general systems theory; the role of Georgian neurophysiologists in emphasizing cognitive aspects of memory role in animal behavior is underlined. The existence of the "one-trial" nonspatial visual recognition memory in cats, as representatives of carnivores with poorly developed vision, is established; it is shown that analogously to primates and rodents in cats the so called rhinal cortex plays a major role in mediating this type of visual cognitive memory. It is shown that in cats, similarly to primates and rodents, parahippocampal cortex (with possible inclusion in this system of the subicular complex) is responsible for visuospatial memory. This new book examines the aspects of cognitive visual memory in cats.
Three groups of BALB/c mice were trained to a food-procuring behavior in a multiple-choice maze allowing operative changes to the environmental geometry. Control animals were trained in maze 1 (M1), which has two variants for transfers between its halves. Maze M2 had a single route for this transfer; animals of experimental group 1 for one trial and those of experimental group 2 for two trials were placed in M2, after which they were placed in M1. The study results showed that regardless of the frequency of and interval between repeats of trajectory segments in M2, the information obtained during this short period was persistently used in solving the task in M1. Despite the fact that the imprinted version of passage contradicted the minimum action principle, the experimental animals differed from controls in not being able to eliminate it from the structure of the skill, which hindered optimization of the behavior.
Background and purpose:
For many years survival and neurological functionality of patients were the main outcome measures after treatment of intracranial aneurysms. But, the variable outcomes of patients operated on in a delayed fashion or before the aneurysm rupture indicate that more precise measures are needed for assessment of not only the neurological but also the neuropsychological outcome. However, development and testing of such new tools requires better understanding of pathomechanisms of neurobehavioral changes evoked by aneurysmal subarachnoid hemorrhage (aSAH), which can be achieved using animal models.
Methods:
We reviewed and selected (1) animal models developed to investigate delayed cerebral vasospasm that could be useful for examining effects of brain injury evoked by aSAH and (2) a battery of neurobehavioral animal testing that can be used for assessment of patients after aSAH.
Results:
For every species used as an aSAH model, a battery of neurobehavioral test exists.
Conclusion:
Albeit some limitations must be recognized, research using animal models of SAH should continue to play a critical role in assessment of cognitive and behavioral functions after aSAH.
We examined correlation between the development of slow potentials in the rhinal cortical region of cats and results of behavioral
testing of visual recognition memory of these animals in the “delayed nonmatching-to-sample” (DNMS) selection version. Among
different types of cognitive memory, the recognition memory occupies a special position because the process of taking off
(retrieval) of a memory trace from the “stores” can be completely and effectively controlled by the experimenter (this process
is initiated only after repetitive presentation of a stimulus identical to that whose trace should be subjected to retrieval
or after presentation of an absolutely new stimulus whose trace had not been formed earlier). Recording of the field potentials
was performed from the surface of the rhinal cortex using stereotaxically implanted mono- or bipolar Ag-AgCl electrodes after
the experimental animals reached a sufficiently high level of successful performance of the test for recognition memory. Analysis
of relations between negative slow potentials in the rhinal cortex and the correctness of performance (according to Spearman’s
nonparametric test) demonstrated the existence of significant correlation between the electrophysiological and behavioral
indices of visual recognition memory only within a late portion (final 10 sec but not initial 10 ones) of the retention interval
for memorizing the trace of single presentation of a visual stimulus. The data obtained are interpreted as a confirmation
of the existence of correlation between generation of negative slow potentials in the rhinal cortical region and the process
of retrieval of the sample from the visual memory stores.
Using of mutislice spiral CT as first line examination for the diagnosis of Acute Facial trauma in the setting of Polytrauma reduces both: valuable time and cost of patient treatment. After a brief clinical examination, MDCT was performed depending on the area of injury, using a slice thickness of 0.65 mm. The obtained data were analyzed using 3D, MIP and Standard axial with Bone reconstruction protocols. 64 polytrauma patients were evaluated with both Anterior and Lateral craniography (plain skull X ray: AP and Lateral) and Multi Slice CT. Craniography detected only 18 cases of traumatic injuries of facial bones, but exact range of dislocation and accurate management plan could not be established. In the same 64 cases, Multislice CT revealed localization of all existed fractures, range of fragment dislocation, soft tissue damage and status of Paranasal sinus in 62 cases (96.8%). In two cases MS CT missed the facial fracture, in one case the examination was complicated because of bone thinness and numerous fracture fragments, in another multiple foreign body artifacts complicated the investigation. The study results show that, CT investigation based on our MDCT polytrauma protocol, detects all more or less serious facial bone injuries.
The role of the posterior parahippocampal area of the brain in spatial types of memory in conditions of one-trial visual perception of the positions of objects was studied by training eight cats to remember the spatial positions of either two different objects covering two of three feeders placed on a test tray (tests for the "object-place" association) or the positions of two of three feeders (tests for place). Each trial used new objects and new positions for the two of three feeders. After training, four cats were subjected to electrolytic lesioning of the posterior parahippocampal area, primarily the parahippocampal cortex, parasubiculum, and presubiculum; the remaining four cats underwent all the surgical procedures except electrocoagulation of nervous tissue; this was the sham-operated control group. Cats of this group showed no impairment to the performance of tests of both types, while the experimental group showed similar levels of impairment to the performance of both tests. Thus, memory for one-trial perception of "object-place" associations and, more simply, two different object places in cats were critically dependent on the posterior parahippocampal area.
Memory for visual recognition in primates is at least partially mediated by the peripheral and entorhinal (i.e., rhinal) areas of the cerebral cortex. The roles of these structures in visual recognition in cats was studied by producing electrolytic combined lesions of the rhinal (perirhinal + entorhinal) areas in a group of cats trained in a modified Wisconsin test apparatus to delayed selection of an object on the basis of its image on presentation of a new object in every trial in the test. Control groups consisted of intact and sham-operated cats. Animals with rhinal lesions were no different from sham-operated and intact animals in the initial training to the rules for correct responding to the objects presented; they also showed no difference at the minimum delay period of 5 sec used in these experiments. However, a statistically significant difference was seen on testing with a delay of 10 sec, demonstrating impairment of intrinsic visual recognition memory.
Monkeys were trained preoperatively on a one-trial learning task in which they were required to associate in memory a novel object and the place in which it had just appeared. After learning the task to a level of 80% correct responses, they received bilateral ablations of either the hippocampal formation or the amygdaloid complex. The monkeys with amygdalectomy showed a small drop in performance initially but then regained their preoperative level. By contrast, the monkeys with hippocampectomy dropped to near-chance levels of performance and remained there throughout postoperative testing. Both groups performed at better than 90% correct responses on a test of recognition memory. These results, taken together with earlier work, suggest that although the hippocampus and amygdala appear to participate equally in object recognition, only the hippocampus is critical for the rapid formation of object-place associations.
Frontal, inferotemporal, and unoperated monkeys were tested on a series of one-trial learning problems involving delayed matching or nonmatching from baited or unbaited samples. All animals tended to choose the new object on the test trial, regardless of their pretrial experience. When this response was correct, frontals performed at a high level; otherwise, they performed poorly. "The analysis suggests that frontal lesions produce abnormal difficulty in suppressing whatever response normally prevails in a given situation." (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Visual memory in monkeys was examined under four different conditions, each with a separate group. In all conditions, the delay between sample and choice was 10 sec, and the delay between trials was 30 sec. The procedural differences were matching or nonmatching with the same two objects presented repeatedly and matching or nonmatching with trial-unique objects. With the customary repetitive stimuli, whether in matching or nonmatching, most monkeys either required prolonged training to solve the problem (over 40 sessions) or failed to solve it, corroborating the learning difficulties reported earlier by others. With trial-unique stimuli, by contrast, most monkeys learned quickly (matching, under 20 sessions; nonmatching, under 5 sessions). Furthermore, in nonmatching with trial-unique stimuli, scores averaged 80% correct in the first session, even though the monkeys were experimentally naive. The results indicate that recognition of a stimulus as familiar or novel is highly developed in monkeys, and that their difficulty with the customary nonspatial visual memory tasks stems from a retardation in noticing and using the mnemonic cue of recovery of presentation. Evidence is presented that this difficulty can be overcome, however, by a simple training procedure that exploits their proficiency at distinguishing familiar from novel stimuli.
Three rhesus monkeys with transection of the fornix were compared with 3 operated control monkeys in 4 memory tasks. They were tested repeatedly at each task until a stable level of performance was achieved. Ss with transection of the fornix were severely impaired in the 3 tasks that tested recognition memory and unimpaired in a test of pure associative memory which was very similar in all but the essential respects to one of the recognition tasks. It is suggested that damage to the hippocampal system in monkeys causes an anterograde amnesia comparable to that observed in human patients with similar lesions and consisting in a specific deficit of recognition memory.
This chapter discusses the delayed response problem. It presents an analysis of the delayed-response problem followed by an examination, in terms of this analysis, of the major determining variables consistently demonstrated in research with both normal and brain-damaged primates. There have been many explanations of response deficits and many interpretations of the delayed-response problem. The more global interpretations were offered before the enumeration of the many variables that influence performance. Hyperactivity and distractibility, and incentive value and deprivation are variables that influence delayed-response performance because they affect these initial reactions. A number of studies, in diverse research areas, consistently correlate one observation with decreased delayed-response performance. At the time of baiting, the tester can only try to get the animal to observe the baiting operation or the bait. While experience and skill certainly help in deciding when the animal has observed, any tester will admit that there are instances when this decision is difficult to make.
This chapter reviews some experimental data regarding learning by primate and non-primate species. It presents some problems on which both primates and representatives of some other vertebrate taxon have been tested. It presents the ways in which learning in primates does not differ from learning in other taxa. The qualitative differences in learning between mammals and nonmammals are much greater and more significant than what learning theorists have recognized. The substantial qualitative similarities in learning by mammals indicate that the differences in learning between primates and other mammals are not so great as they seemed to many primatologists a few years ago.
Abstract The topic of multiple forms of memory is considered from a biological point of view. Fact-and-event (declarative, explicit) memory is contrasted with a collection of non conscious (non-declarative, implicit) memory abilities including skills and habits, priming, and simple conditioning. Recent evidence is reviewed indicating that declarative and non declarative forms of memory have different operating characteristics and depend on separate brain systems. A brain-systems framework for understanding memory phenomena is developed in light of lesion studies involving rats, monkeys, and humans, as well as recent studies with normal humans using the divided visual field technique, event-related potentials, and positron emission tomography (PET).
Theory of learning and perception inspired by contemporary neurophysiology. Harvard Book List (edited) 1971 #150 (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Cats with lesions in the proreal and anterior sigmoid gyri and substantial but subtotal degeneration in the mediodorsal thalamic nucleus were studied for 6 years post-operatively. The control group consisted of normal cats matched for age and previous experience. The results reported here and in Warren's previous progress report indicate that frontal cortical lesions result in several behavioral changes in cats which are like those seen in rhesus monkeys after frontal ablations: impairments in discrimination reversal, double alternation and active avoidance learning, retardation in the rate of habituation to novel neutral stimuli, and a decrease in aggression in competitive social situations. Cats with larger frontal lesions made more errors in reversal learning than cats with smaller lesions. Frontal cats, unlike frontal rhesus monkeys, are not hyperactive post-operatively and retain some capacity for learning delayed response in the WGTA. It is impossible at present to tell whether these discrepancies reflect species differences in the organization of the frontal lobe system or whether the frontal cortex spared in this series of cats is sufficient to mediate delayed response and to prevent the occurrence of hyperactivity.
A neural model is presented, based largely on evidence from studies in monkeys, postulating that coded representation of stimuli are stored in the higher-order sensory (i.e. association) areas of the cortex whenever stimulus activation of these areas also triggers a cortico-limbo-thalamo-cortical circuit. This circuit, which could act as either an imprinting or rehearsal mechanism, may actually consist of two parallel circuits, one involving the amygdala and the dorsomedial nucleus of the thalamus, and the other the hippocampus and the anterior nuclei. The stimulus representation stored in cortex by action of these circuits is seen as mediating three different memory processes: recognition, which occurs when the stored representation is reactivated via the original sensory pathway; recall, when it is reactivated via any other pathway; and association, when it activates other stored representations (sensory, affective, spatial, motor) via the outputs of the higher-order sensory areas to the relevant structures.
This review covers recent research on the neural process through which a novel stimulus becomes familiar. Lesion and recording studies have provided data sufficient to outline a tentative stimulus-recognition circuit and to suggest how the circuit might operate to form the new and relatively lasting stimulus traces that must underlie delayed stimulus recognition. The research has reached a stage where further progress could well be hastened by interaction between experiment and the formal, neurobiologically constrained models that are beginning to appear.
Recognition is the process by which a subject is aware that a stimulus has been previously experienced. It requires that the characteristics of events are perceived, discriminated, identified and then compared (matched) against a memory of the characteristics of previously experienced events. Understanding recognition memory, its underlying neuronal mechanisms, its dysfunction and alleviation of the latter by putative cognition enhancing drugs is a major research target and has triggered a wealth of animal studies. One of the most widely used animals for this purpose is the rat, and it is the rat's recognition memory which is the focus of this review. In this first part, concepts of recognition memory, stages of mnemonic processing and paradigms for the measurement of the rat's recognition memory will be discussed. In two subsequent articles (parts II and III) we will focus on the neuronal mechanisms underlying recognition memory in rats. Three major points arise from the comparison of paradigms that have in the past been used to assess recognition memory in rats. First, it should be realized that some tasks which, at face value, can all be considered to measure recognition memory in rats, may not assess recognition memory at all but may, for example, be based on recall rather than recognition. Second, it is evident that different types of recognition memory can be distinguished and that tasks differ in the type of recognition memory taxed. Some paradigms, for example, measure familiarity, whereas others assess recency. Furthermore, paradigms differ as to whether spatial stimuli or items are employed. Third, different processes, ranging from stimulus-response learning to the formation of concepts, may be involved to varying extent in different tasks. These are important considerations and question the predictive validity of the results obtained from studies examining, for example, the effects of putative cognition enhancing drugs.
1. Dogs had considerable difficulty learning a delayed-non-matching-to sample task at a short delay (approximately 5 seconds) for an extended period (900 trials). Only 3 of 19 dogs met the learning criterion. 2. Acquisition on the DNMS task was markedly improved when a pause was introduced on presentation of the stimulus objects, when the objects were approximately 30 cm from the dog; eleven of 16 dogs learned the task within 600 trials. 3. Dogs learned the task more rapidly at 20 and 30 second delays than at 10-second delays. This indicates a transfer of learning. 4. Dogs that did learn the task were able to perform at accuracy greater than 85% at delays of 150 and 200 seconds. At a 5-minute delay, performance was at 75%. 5. When the animals were switched to a repeated object paradigm, accuracy markedly declined. 6. The improved performance produced by introduction of the pause is attributable to: (1) presenting the object at a distance longer than the dogs' near point, and (2) allowing increased processing time.
Vertebrate Memory, its Characteristics and Origin
Beritashvili (Beritoff) IS (1971) Vertebrate Memory, its
Characteristics and Origin. Plenum Press, New York.
The delayed-response problem In: Behavior of Nonhuman Primates (Schrier AM
- Hi Fletcher
Fletcher HI (1965) The delayed-response problem In:
Behavior of Nonhuman Primates (Schrier AM, Harlow
HF, Stolnitz F, eds.). Academic Press, New York,
p.129169.