Episodic-like memory
[1] This ability in animals is considered 'episodic-like' because there is currently no way of knowing whether or not this form of remembering is accompanied by conscious recollection—a key component of Endel Tulving's original definition of episodic memory.
Many criticisms of this area of research have been made including questioning how accurately we can attain this information simply based on behavioural criteria and non verbal tests.
[3] The ability to encode and retrieve past experiences relies on the circuitry of the medial temporal lobe, a brain structure that includes the hippocampus and other para-hippocampal cortical areas.
The organization of these brain areas is largely conserved across mammalian species as are the major pathways that information travels between the medial temporal lobe and the neocortex.
This information is then projected onto subdivisions of the hippocampus which are connected by a path which begins with the dentate gyrus, continuing to area CA3, then CA1, and finally through to the subiculum.
Animal lesion studies have also provided evidence related to the importance of particular brain structures in episodic-like memory.
Rats with medial prefrontal cortical lesions showed impairment on the ‘where’ component suggesting that this area contributed to retrieving information on object location.
[7] Similarly, hippocampal lesions severely impacted all three components (what, where, and when) suggesting that the hippocampus is responsible for detecting new events, stimuli, and places when forming new memories and on retrieving that information later on.
[citation needed] Recent research regarding mental time travel and episodic-like memory has focused on determining whether there are any non-human animals that demonstrate future planning and under what conditions they do so.
Flexibility within episodic-like memory has been demonstrated within a study by Clayton et al. involving the caching of perishable and non-perishable foods.
Results confirmed this reasoning demonstrating that these birds possess a flexible episodic like memory system where they can update their information after the time of encoding.
In a second part of this study, they tested whether scrub jays remember which particular individual was present when they made specific caches.
A study of the rufous hummingbird found they were able to learn and remember which flowers in an arrangement contained a nectar reward.
Similar cognitive abilities and foraging strategies were also observed in a study of the green-backed firecrown, another species of hummingbird.
A study at the University of Kentucky aimed to determine whether pigeons could recall their previous actions with regard to certain hues presented either with or without food.
The pigeons were required to recall what the previous stimulus had been and how they had reacted in order to formulate a correct response and receive a reward.
Due to their similarities to humans, researchers have been interested in looking into the episodic memory abilities of non-human primates.
For example, Schwartz performed an experiment with gorillas in a task requiring the animal to select the appropriate card that represented the food he had just eaten and who had given it to him.
[14] While the gorilla appropriately identified the food items and trainer, it is unclear if he recalled the event or chose the answer most familiar to him.
[15] Furthermore, Hampton had mixed results when testing rhesus monkeys; while demonstrating memory for the location and type of food, they lacked sensitivity to when they acquired the knowledge.
[17] After five minutes and again at one hour, the apes were presented with the choice of selecting hidden frozen juice, less-preferred grapes, or an empty platform.
Humans exhibit age-dependent performance with inverted U-shaped results, meaning ability increases in childhood, stabilizes for a few years and then descends as adulthood progresses.
The similarities in findings found may indicate these primates and humans share some information encoding and storage mechanisms.
[17] Future research may be done with a larger sample size and different experiments to replicate the inverted U-shape findings.
Most examples of episodic-like memory are based on animals in captivity, however a study on free-foraging Egyptian fruit bats (Rousettus aegyptiacus) has found evidence for planning of foraging based on both their knowledge of the location and availability of food, but also temporal understanding of food tree seasonality.
The experimenters suggest the error rate can be accounted for by a foraging strategy, in which multiple feeding locations are visited at fixed times.
Randolf Menzel also provided evidence for episodic memory in honey bees by examining their learning of spatio-temporal tasks.
[2] It suggests that animals are incapable of anticipating future needs, and any future-oriented behaviours they exhibit are either fixed action patterns or cued by their current motivational state.
Another criticism is that it is possible that in many cases animals are simply exhibiting Garcia-type learning which involves conditioned taste aversion.
