Episodic Memory In Non-Humans Literature Reviews Examples

ANIMALS OTHER THAN HUMAN HAVE EPISODIC MEMORIES.

Pause, B. M et al., (2015). Perspectives on episodic-like and episodic memory. - PubMed - NCBI. Retrieved 26 February 2015, from: http://www.ncbi.nlm.nih.gov/pubmed/23616754
Researchers Dickinson and Clayton have used research methods which rely on the food storage behavior of birds to study the episodic memory in some types of animals. The birds used in the study were scrub jays which were observed to be capable of having a memory of when and where they had caught certain types of food they had initially caught. Subsequent studies also revealed that corvids could similarly use a number of tools and hence indicating object permanence together with an ability to anticipate for the future which also explains the probability of a presence of the theory of mind (Pause et al., 2015).
Conditional research on fear in animals is another research method system that has also been used by different researchers where the animals receive a food stimuli indicator when they were transiting from a large chamber that is well lit to one that is small and dark. After a delay of 24 hours, when the animals were returned to the big chamber, it was observed that they generally attempted to avoid the initially darker chamber. This type of response is consequently described as type of learning that is associative and linked with strong emotions that arise from painful environments in particular spatial scenarios indicating the presence of similarities between one-trial fear conditioning and the human memory (Pause et al., 2015).
The novelty-preference paradigm is another research method that has been used based on the attraction of mice and rats by novel objects. These rodents were exposed to a choice of old and novel objects and were observed to spend more time exploring the more interesting novel object (Pause et al., 2015). This therefore suggested that they remember the physical characteristics of the old object and hence reflecting a behavior motivated by emotional activation which triggers episodic memory formation. All these research works prove the existence of episodic memories in animals.
Sadie, Dingfelder, F. (2007) Can rats reminisce? American Psychological Association 38 (6): 26. Retrieved from: http://www.apa.org/monitor/jun07/canrats.aspx
A study of the scrub-jay birds by Nicola Clayton and Anthony Dickinson took advantage of the birds' natural tendency to hoard food, including perishable items like wax worms and more long-lasting ones like nuts. It was observed that the birds returned first to the wax worm caches after a short passage of time while they were still fresh and not after they had begun to rot. This indicated that the birds knew what food they had hidden where they were and when they ought to eat them and hence the three ‘Ws’ definition of episodic memory (Sadie, 2007).
In study carried out in 2006 by Jonathan Crystal and Stephanie Babb, it was discovered that lab rats are able to remember what, where and when they initially discovered food in a maze. They placed the rats in a radial-arm maze and put the different flavors of food pellets at the end of each arm. The animals were observed to race down the arms eating the food they found. However, after either a short or a long delay, the rats would return to the maze finding that the arms they had already visited no longer had any food, with the exception of those that had held raspberry or grape flavored pellets. These food flavors were magically replenished during the long term but not the short-waiting time. The rats therefore had to quickly learn to revisit the arms with special foods after the 6 hour wait and not after returning just an hour later (Sadie, 2007).
Another study of rats also indicated their possession of episodic memory. Through a lab experiment by University of Georgia psychologists Jonathan Crystal and Stephanie Babb published in the Current Biology, 2006, rats were observed to remember the points at which they had found and ate different flavored foods in a maze. All these studies therefore show that rats recall particular events from their past and hence episodic memory.
Sadie, Dingfelder, F. (2009). The stuff of memories. American Psychological Association. 40 (9): 38. Retrieved from: http://www.apa.org/monitor/2009/10/memories.aspx
In a study by Eichenbaum and Magdalena Sauvage, rats were given cups that were filled with specific scents that were mixed into different materials used for digging like coffee mixed into chips of wood or oregano mixed into beads made of plastic. Later on, they tested the ability of the rats to have a memory of the same pairs of odors that were mixed. For instance there was the oregano that was mixed in plastic containers with the other pairs that were mismatched with other odors like oregano that was mixed in chips of wood. The rats therefore had to indicate a different response to the all the new pairings as compared to those they had experienced initially. This procedure according to Eichenbaum, helped give a complete assurance that the animals would not rely on the mere impression of having initially smelled the oregano or dug into the plastic beads before (Sadie, 2009). The rats rather had to hold the memory of the unique association between the odors and the mixing material. The rats therefore had to quickly learn to only look for the treats that were in the mix and scent combination that they had sniffed before. It was observed therefore that for the rats that had undergone an operation to remove their hippocampi had responded randomly. This conclusively indicated the important role of the hippocampus in combining the 3 ‘Ws’ information.
In yet another experiment by Eichenbaum and Robert Komorowski, activated cells in the rats' hippocampi were recorded while they sniffed into sand that was scented placed the floor in varied locations. Activated cells were also recorded to test the memory of the animals on whether or not they could place the scents to where they had sniffed before. It was observed that while still in the learning phase, the hippocampal neurons of the animals appeared to spike the rats sniffed at specific locations, the cells however did not favor specific scents (Sadie, 2009). With time, the scientists pared down the firing to instances when the scents were present in a particular place initially encountered. False responses would be observed when there were misfires. This is explained by the fact that the hippocampal cells are capable of acquiring position information.
Crystal, J. (2010). Episodic-like memory in animals. Behavioral Brain Research, 215(2), 235-243. doi:10.1016/j.bbr.2010.03.005
Clayton and Dickinson performed experiments with the scrub jays to prove the existence of episodic-like memory in animals. They provided the bird with an opportunity to cache and retrieve two food types that differed in their palatability and perishability i.e. wax warms (more palatable but highly perishable) and peanuts (less perishable but less palatable). They discovered that the jay birds retrieved the more palatable wax warms first when they were still fresh and later the peanuts. This depicted that the birds sense of what (fresh wax warms or peanut), where (location of the cached food) and when (time of caching and recover) (Crystal, 2010). Similar studies of hoarding birds such as black-capped chickadees and magpies have shown similar results.
Babb and Crystal modified a prior experiment with rats in a maze to study if rats have a sense of where, when and what. The rats are set in a maze where they consume certain types of food (i.e. chow-flavored, raspberry and grape flavored foods) during the study phase with the raspberry and grapes being replenished after some intervals. They are then set in a retention phase for varying lengths of time. They are then set back to the maze during the test phase. The researchers realized that the rats visited the locations that had raspberry and grapes at almost the time when they were being replenished, while they reduced the rate of visits to the chow-flavored foods’ location (Crystal, 2010). This is also a clear indication that nonhumans have a sense of where, what and when. This implies that non-humans have episodic memory tendencies.
The two experiments therefore prove that animals have episodic-like memory with the three ‘Ws’ classic definition (i.e. the what, when and where) of episodic memory by Tulving.
Morris, R. (2001). Episodic-like memory in animals: psychological criteria, neural mechanisms and the value of episodic-like tasks to investigate animal models of neurodegenerative disease. Philosophical Transactions of the Royal Society B: Biological Sciences, 356(1413), 1453-1465. doi:10.1098/rstb.2001.0945
The episodic memory test for mice and rats has allowed the simultaneous measurements of the memory of temporal organization of objects that are presented in an open-field which also contains those in spatial positions where these objects are encountered. It has also been capable of detecting whether the where, what and when information has been included to a whole episodic memory dimension. Research in this area has therefore involved animals which receive trial sample that have four copies of a new object that are identical. After fifty minutes in between the different trials a test trial is administered whereby two old objects retrieved from the initial sample are presented at the same time with the two other recent objects that were introduced during the subsequent sample trial. During this trial therefore there were some old and recent objects that were relocated to a new place. Observations demonstrate that the mice and rats were capable of associating the temporal and spatial object information just after a one episode of exposure to the stimulus constellations (Morris, 2001). This interesting ability is therefore in agreement with the concept of episodic memory in animals.
Scientists are therefore using the inferences from such studies to assist in the treatment of some degenerative human diseases like the Alzheimer’s disease. Up to date there have been no definitive diagnostic test made available to identify AD in living patients. This is mostly because of the immense expense and time consumed in the establishment of diagnostic tools for AD.
Therefore research development on episodic memory in animals will help in the identification of a new cognitive marker during the presymptomatic stage of AD with bases on episodic memory functioning (Morris, 2001). With this diagnostic episodic memory test the distinction of individuals with presymptomatic stages of AD from those with MCI can be made. This will then make it possible to delay the onset of the disease or to reduce its progression.

References

Crystal, J. (2010). Episodic-like memory in animals. Behavioral Brain Research, 215(2), 235- 243. doi:10.1016/j.bbr.2010.03.005
Morris, R. (2001). Episodic-like memory in animals: psychological criteria, neural mechanisms and the value of episodic-like tasks to investigate animal models of neurodegenerative disease. Philosophical Transactions of the Royal Society B: Biological Sciences, 356(1413), 1453-1465. doi:10.1098/rstb.2001.0945
Pause, B. M et al., (2015). Perspectives on episodic-like and episodic memory. - PubMed - NCBI. Retrieved 26 February 2015. Retrieved from: http://www.ncbi.nlm.nih.gov/pubmed/23616754
Sadie, Dingfelder, F. (2007) Can rats reminisce? American Psychological Association 38 (6): 26. Retrieved from: http://www.apa.org/monitor/jun07/canrats.aspx
Sadie, Dingfelder, F. (2009). The stuff of memories. American Psychological Association. 40 (9): 38. Retrieved from: http://www.apa.org/monitor/2009/10/memories.aspx