Archive for October, 2011

Professional Resume Writing Services

Due to the recent economic downturn, the numbers of job advertisements have fallen considerably whereas applications per vacancy have more than doubled. Recruiters have or do spend as little time as possible per Resume due to increase in volume of resumes they have to handle. A recent report from Kaonix, a premier online recruitment solutions agency, indicates that the average number of applications per vacancy has doubled when compared to 2008 whereas the job advertisements have dropped by 69% in the last two years. Your resume should clearly and succinctly communicate your value to grab attention in the first round of selection itself. It definitely pays to get your resume composed by professionals who knows what employers or recruiters are looking for. CustomEssayPapers.com professional resume writing services provide high impact resumes emphasizing your accomplishments and strengths and helps you achieve your career objectives in. Our HR experienced professional resume writers help you compile a resumes, covering letters, follow up and Thank you letters with powerful and relevant content clearly stated in excellent English. Our qualified experts are equipped to deliver custom written resumes for entry levels, professional careers, company executives, Federal or defense employments.

Click here to test our quality custom essay writing service for only $1!

CustomEssayPapers.com Resume Writing Services provide

  • Professionally written high impact resumes for any job application
  • Impressive resume content and structure developed by experts
  • HR experienced qualified professional resume writers for quality products

Whether you are out for a change in your career, looking for a promotion or just unemployed, CustomEssayPapers.com professional resume writers have the background and knowledge to develop a resume with visual appeal and critical content to support your candidature. We provide online interactive resume writing services support to ensure all your instructions and specifications are clearly understood and adhered to. We respect your privacy and your personal information is treated confidential and never shared with a third party.

Choose CustomEssayPapers.com Resume Writing Services for

  • Result oriented resume writing services
  • Interactive 24/7 support until satisfactory delivery
  • Confidentiality and security of personal information
  • Timely delivery
  • Reasonably priced professional resume writing services.

Resumes attached to the applications should clearly convey your curriculum vitae with proper diction and cadence. We carefully assign experts with the correct background and exposure to your field of activity to provide you with a perfectly designed and executed resume that is certain to grab prospective employer’s attention and interest. Our services are provided at the most competitive rates and we guarantee 90% chances for an interview with our resumes. We also provide choice of your document formats, you may choose *.txt,*.doc or *.pdf at your convenience.

CustomEssayPapers.com Resume Writing Professionals are

  • HR experienced qualified experts.
  • Experts with knowledge in all types and levels of employment
  • Experienced writers with specific domain knowledge and exposure
  • Equipped to design and structure quality resumes for any job application

Animal Memory

By Heather Williams

Download free PDF version of this essay

Introduction

humans memoryHuman memory is a broad topic, encompassing a variety of different types of memory such as short-term, long-term, working, and episodic, among others. Additionally, the function of memory is not limited to one area of the brain. The regions of the striatum, amygdala, frontal lobes, and cerebellum have all received attention when studying how memory is involved in skills, habits, and conditioning (Kesner & Hopkins, 2006).

While a great deal of research has been conducted concerning the human brain and memory, another field of such research exists. It is aimed at understanding the ways in which human memory and that possessed by animals are alike. This research is very important because it does not only help us understand animals; it helps us understand ourselves as well. Realizing the similarities animals and humans share in the memory sphere can be yet another step to comprehension of the mystery of nature. It is not only a question of biology; it is a question of life.

The following research reveals that animals and humans share the capacity for episodic memory and that in both types of organisms, the hippocampus plays a central role.

The Concept of Episodic Memory

Episodic memory is the type of memory associated with personally experienced events and is therefore described as being autobiographical. It is concerned with “what happened and where and when it happened” (Dere, Kart-Teke, Huston, & De Souza Silva, 2006, p.2). This form of memory, which occurs automatically, involves not only the stimulus, or event, but also a variety of spatial and temporal information. However, episodic memory is different from other types of memory, such as semantic memory. The latter involves the storage and recollection of facts and events without the personal connection. Episodic memory, on the other hand, requires that the individual was an intimate participant in the event remembered. For example, poems learned by heart stay in the semantic memory, while class picnic is stored in the episodic memory.

episodic memoryIn order to experience episodic memory, three simultaneous conditions must be met. One major requirement of episodic memory is that of “autonoetic awareness.” This concept refers to the actual awareness of remembering an experienced event and differs from merely being familiar with the event or being aware of the present moment (for instance, to remember a class picnic you need to have participated in it). Second, an individual must be able to sense time, which provides information about one’s past, allows one to remain aware of the flow of events, and enables consideration of or planning for the future. Without sense of time episodic memories cannot be organized and will ultimately mix all together. Taking the same example with class picnic, a person needs to be aware that it was soon after Easter celebration but before spring finals. Finally, the individual must have the capacity to realize that he or she exists as an entity separate from the surrounding world. This is known as “sense of self”. Humans do possess it and this sense of self naturally brought about the ponderings about “sense of existence” (first documented in the Ancient Greece). These three conditions enable humans to not only mentally travel back into the past and relive an event, but also to travel mentally into the future. Additionally, humans are able to give consideration to what they know and perceive, an activity known as metacognition (Dere, Kart-Teke, Huston, & De Souza Silva, 2006).

Episodic Memory in Humans and Animals

Metacognition

metacognitionResearch evidence exists that suggests a variety of animals possess episodic memory. Even though the abovementioned criteria presuppose a language component behind them, studies have shown that animals retain episodic memories much in the same manner as do humans. Metacognition, or the ability to think about what one knows, is a characteristic of humans and associated with episodic memory. That is, subjects who are able to effectively elaborate on their own cognitions are thought to have metacognition. It has already been demonstrated by experiments that animals may possess the ability as well. In one experiment, rhesus monkeys were given a memory test. If unsure of the correct answer, the monkeys would request more information (they communicated with humans using gestures); however, if the correct answer was known, the monkey immediately responded. This suggested that the monkeys were aware of what knowledge they possessed. However, this quality of memory may not exist in other animals. For example, in one study pigeons had to classify a monitor with illuminated pixels as being either sparse or dense. Correct answer was rewarded by food pellets, and incorrect answer was not rewarded. Occasionally, the birds had the opportunity to pick the response that they were uncertain whether the screen was sparse or dense. In case pigeons picked this response they received a small number of food pellets (smaller than for the correct answer). Researchers found that when given the choice of three responses in a discrimination test, correct, incorrect, and unsure, would often select the “unsure” response if the task was difficult. The notion of “unsure” response in this case meant that pigeons did not exactly know whether the response was absolutely correct or Pegions memoryabsolutely incorrect. It was either completely unknown to the pigeons so that they could not compare it with their experience or closely similar to either correct or incorrect option, but not totally coinciding. At first one might have thought that true thinking on human level was involved. Such conclusion could be drawn because if pigeons had trusted their inborn instincts and reflexes only, they would never have picked the “unsure” variant. However, when the “unsure” option was removed, performance upon the test did not improve, suggesting that pigeons were perhaps using the “unsure” option indiscriminately and did not possess the ability to think about what they knew. Besides, it is also important to know that pigeons might have picked the “unsure” option simply because they knew that in this case they would still get reinforcement, and there was no “correct – incorrect” risk for them. So it was mostly survival instinct, and not the human-like track of thought.

Recall of Past Events

Another quality indicative of episodic memory is the ability to consciously recall past events. Research indicates that apes do indeed possess this human ability, as evidenced by one animal recalling where an object of interest had been hidden almost 16 hours after seeing the experimenter hide it and then taking the initiative to contact an uninvolved caregiver and lead that individual to the object. Additionally, at the time of recall, the animal was in a completely different environment and given no cues to aid in even remembering that the event had occurred.

ratsBabb and Crystal (2006) demonstrated the ability of rats to recall past events in combination with “where and when” the events occurred. These animals were given access to locations that contained either flavored food or non-flavored chow. One of the flavored foods was then devalued by overfeeding it to the rat to the point of satiation or pairing it with an aversive flavor such as lithium chloride. Results indicated that the rats avoided the devalued flavor while still seeking out the other flavors. The researchers concluded that the rats utilized episodic memory to recall the past events of aversion to one of the flavors and alter their behavior to seek out only the desirable flavors. Similar studies, which documented rats spending greater amounts of time exploring familiar objects than new ones, even when the locations of the objects were shifted, provide support for the notion that rats can recall the “where and when” of past events.

However, another experiment shows that rats are not able to use their past experience to modify their present actions. In this experiment rats had to retrieve food after having been shown that in case of delay food from one side of the maze becomes degraded, while food from the other side stays edible. Even after extensive training rats continued to deliver food from both sides of the maze with little preference for the non-degraded side (Kart-Teke, De Souza Silva, Huston, & Dere, 2006).


Temporal Order Memory

A third characteristic of episodic memory is temporal order memory, or the ability to recall a specific sequence of events. Studies have demonstrated an interesting biological similarity among humans and animals in this regard. Research has demonstrated that humans, rats, and monkeys all possess the capability to remember a sequence of odors or objects after some elapsed time. Lesions to the portion of the brain called the medial prefrontal cortex have been shown to inhibit this ability in not only humans, but also non-human primates and rodents. However, these lesions do not alter the ability to recognize new or familiar objects. This research suggests that different areas of the brain are responsible for different types of memory and that humans and animals possess similarities in brain anatomy and function with regards to memory.

Eichenbaum, Fortin, Ergorul, Wright, and Agster (2005) explored this concept in depth in an experiment involving rats and a series of odors. Of particular interest to the researchers was the role of the hippocampus in temporal memory. Rats were presented with a series of odors comprised of various household scents. Afterwards, the rats were again presented with two of the odors and prompted to select the one that had occurred earlier in the initial sequence presentation. Different pairs of odors were presented with the prompt, some of which occurred two odors apart in the initial sequence and some that had occurred three odors apart. For example, researchers first presented the rats with odors A, B, C, D, and E. Then, they presented the rats with odors A and C (two odors apart) or odors A and D (three odors apart). Results indicated that normal rats were able to correctly identify which of the odors in the pair came first at least approximately 70% of the time. Interestingly, the rats exhibited greater accuracy when the pairs consisted of odors three or more positions apart in the initial sequence.

Once this first trial was completed, the researchers repeated the experiment with rats given lesions in the hippocampus area of the brain. Rats in the control group performed equally well as their counterparts in the previous experiment; however, rats with hippocampal lesions had great difficulty in determining which odor had occurred first in the initial series. For example, normal rats correctly identified odor B as coming before odor E over 80% of the time. Rats with lesions could only correctly identify odor B as coming first less than 60% of the time, a percentage close to that of mere chance. Researchers concluded from these experiments that like humans, rats possess the ability to recall the sequence of events in an experience and the hippocampal portion of the brain governs that ability.

Retrospective and Prospective Memory

Episodic memory allows one to, in a sense, time travel to the past or future to either relive an event or predict a future event based upon past knowledge. This is referred to as retrospective and prospective memory, respectively. Like humans, research has indicated that some animals may be capable of these functions. Studies indicated that pigeons are able to anticipate future events based upon a recent set of actions. However, unlike humans who retain information for decades, the retention intervals of pigeons are relatively short. For example, the pigeons successfully coped with a situation based on their previous experience. When that same situation was proposed to them a week later the pigeons acted as if they had never before dealt with it.

carrier-pigeon-faster-than-internetEvidence for retrospective memory has also been demonstrated in dolphins, non-human primates, and rats. This evidence showed itself through the same course of experiments, which were previously conducted on the pigeons. However, unlike humans who are able to use both retrospective and prospective memory in conjunction, these animals typically only use one or the other. In lab experiments, for example, rats associated chocolate with unpleasant experiences because once LiCl was added to it (retrospective memory). However, they never took into account the possibility that other types of food (bananas or grapes) may also be contaminated by LiCl in the future (prospective memory). Also, if prospective memory is used to complete a task, in animals it is linked with the near future, whereas humans have the ability to think much further ahead in time (Dere, Kart-Teke, Huston, & De Souza Silva, 2006).

Ferbinteanu and Shapiro (2003) investigated retrospective and prospective memory in rats and the role of the hippocampus in both types. Rats were placed in a wooden maze in which they were required to move from the start arm of the maze to the goal arm in order to gain a food reward. The location of the goal remained constant while the start location varied. Once the rat could reliably find the goal arm regardless of starting point, the goal location was changed. In the goal arms, retrospective memory was utilized to in recalling the different start arms; in the start arms, prospective memory guided the rat to the goal. Rats in the experimental group were then subject to fornix lesions or sham surgery to determine if the maze task required the functioning of the hippocampal region. While traversing the maze, quantitative measurements of brain electrical activity in various portions of the hippocampus were recorded. When comparing the performance and brain activity of these rats to control group rats, researchers found that different groups of hippocampal neurons fired when the rat utilized either retrospective or prospective memory to move through the maze. It was rather easy to identify for the reason that groups of hippocampal neurons responsible for retrospective and prospective memory are situated in different parts of the brain. Additionally, retrospective memory was used more frequently than prospective. In rats with brain lesions, both forms of memory were diminished. Even though these rats remembered the tasks procedured and started them readily, their chances of successful completion were significantly smaller. On the other hand, the animals with sham lesions performed well after surgery, and their performance continued to improve. This research suggests the point that the neuronal signals in the various hippocampal areas were necessary for task performance.

These findings are in line with the knowledge concerning the role of the hippocampus in human episodic memory. In the experiment hippocampal neurons demonstrated prospective, place and retrospective coding. Therefore, the neurons appeared to encode memory demands and not a location or a specific sequence of movements through the maze. However, they provided a crucial signal for distinguishing the same events that happened in different moments of the time by encoding the recent past, the present and the near future simultaneously. Thus hippocampal neurons contribute to the mechanism of episodic memory.

Summary and Conclusions

thinking_monkeyEpisodic memory is concerned with not only specific events in an organism’s life, but also the “where and when” of their existence. Research in both humans and a variety of animals indicates that this type of memory is an overlapping feature. Animals have been shown to exhibit metacognition rats, are able to utilize temporal order memory to recall a specific sequence of events. Retrospective memory, another component of episodic memory in humans, has been demonstrated in , non-human primates, and rats.

However, not all animals possess the capability for this type of memory; research indicated that pigeons were unable to demonstrate metacognition, an important component of episodic memory. In conjunction with studies involving tasks requiring memory, many research studies alter portions of the brain hypothesized to play a central role, such as the hippocampus. The main idea of such research is that it is possible to influence memory not only in psychological (such as hypnosis) but also purely physical ways. It also explains the medical cases when after suffering a head trauma a person lost different memory functions (such as short-term memory or memorizing numbers). Results in this area indicate that the hippocampus plays a dolphin-kisscentral role in episodic memory in humans and animals alike. Study of the similarities and differences between human and animal memory, particularly in the area of brain anatomy and function, may provide important insights into the evolution of memory across species and provide scientists with the explanation of memory mysteries both for animals and humans. In perspective, such research will also be important for developing treatments for different mental conditions directly connected with memory for example, amnesia or loss of short-term memory. Research results may be able to provide clues for treatment of such diseases – from the choice of necessary medicine (after studying the influence necessary surgical operations on certain parts of the brain.

References

Babb, S.J. & Crystal, J.D. (2006). Episodic-Like Memory in the Rat. Current Biology, 16, 1317-1321.

Dere, E., Kart-Teke, E., Huston, J.P., & De Souza Silva, M.A. (2006). The Case for Episodic Memory in

Animals.

Neuroscience and Biobehavioral Reviews. Retrieved November 24, 2006, retrieved from

http://www.sciencedirect.com/science

Eichenbaum, H., Fortin, N.J., Ergorul, C., Wright, S.P., & Agster, K.L. (2005). Episodic Recollection in

Animals: “If It Walks Like a Duck and Quacks Like a Duck…” Learning and Motivation, 36, 190-207.

Ferbinteanu, J. & Shapiro, M.L. (2003). Prospective and Retrospective Memory Coding in the Hippocampus.

Neuron, 40, 1227-1239.

Kart-Teke, E., De Souza Silva, M.A., Huston, J.P., & Dere, E. (2006). Wistar Rats Show Episodic-Like

Memory for Unique Experiences. Neurobiology of Learning and Memory, 85, 173-182.

Kesner, R.P., & Hopkins, R.O. (2006). Mneumonic Functions of the Hippocampus: A Comparison

Between Animals and Humans. Biological Psychology, 73, 3-18.

Animal Memory

Introduction

Human memory is a broad topic, encompassing a variety of different types of memory such as short-term, long-term, working, and episodic, among others. Additionally, the function of memory is not limited to one area of the brain. The regions of the striatum, amygdala, frontal lobes, and cerebellum have all received attention when studying how memory is involved in skills, habits, and conditioning (Kesner & Hopkins, 2006).

While a great deal of research has been conducted concerning the human brain and memory, another field of such research exists. It is aimed at understanding the ways in which human memory and that possessed by animals are alike. This research is very important because it does not only help us understand animals; it helps us understand ourselves as well. Realizing the similarities animals and humans share in the memory sphere can be yet another step to comprehension of the mystery of nature. It is not only a question of biology; it is a question of life.

The following research reveals that animals and humans share the capacity for episodic memory and that in both types of organisms, the hippocampus plays a central role.

The Concept of Episodic Memory

Episodic memory is the type of memory associated with personally experienced events and is therefore described as being autobiographical. It is concerned with what happened and where


and when it happened” (Dere, Kart-Teke, Huston, & De Souza Silva, 2006, p.2). This form of memory, which occurs automatically, involves not only the stimulus, or event, but also a variety of spatial and temporal information. However, episodic memory is different from other types of memory, such as semantic memory. The latter involves the storage and recollection of facts and events without the personal connection. Episodic memory, on the other hand, requires that the individual was an intimate participant in the event remembered. For example, poems learned by heart stay in the semantic memory, while class picnic is stored in the episodic memory.

In order to experience episodic memory, three simultaneous conditions must be met. One major requirement of episodic memory is that of autonoetic awareness. This concept refers to the actual awareness of remembering an experienced event and differs from merely being familiar with the event or being aware of the present moment (for instance, to remember a class picnic you need

to have participated in it). Second, an individual must be able to sense time, which provides information about ones past, allows one to remain aware of the flow of events, and enables consideration of or planning for the future. Without sense of time episodic memories cannot be organized and will ultimately mix all together. Taking the same example with class picnic, a person needs to be aware that it was soon after Easter celebration but before spring finals. Finally, the individual must have the capacity to realize that he or she exists as an entity separate from the surrounding world. This is known as sense of self. Humans do possess it and this sense of self naturally brought about the ponderings about sense of existence (first documented in the Ancient Greece). These three conditions enable humans to not only mentally travel back


into the past and relive an event, but also to travel mentally into the future. Additionally, humans are able to give consideration to what they know and perceive, an activity known as metacognition (Dere, Kart-Teke, Huston, & De Souza Silva, 2006).

Episodic Memory in Humans and Animals

Metacognition

Research evidence exists that suggests a variety of animals possess episodic memory. Even though the abovementioned criteria presuppose a language component behind them, studies have shown that animals retain episodic memories much in the same manner as do humans. Metacognition, or the ability to think about what one knows, is a characteristic of humans and associated with episodic memory. That is, subjects who are able to effectively elaborate on

their own cognitions are thought to have metacognition. It has already been demonstrated by experiments that animals may possess the ability as well. In one experiment, rhesus monkeys were given a memory test. If unsure of the correct answer, the monkeys would request more information (they communicated with humans using gestures); however, if the correct answer was known, the monkey immediately responded. This suggested that the monkeys were aware of what knowledge they possessed. However, this quality of memory may not exist in other animals. For example, in one study pigeons had to classify a monitor with illuminated pixels as being either sparse or dense. Correct answer was rewarded by food pellets, and incorrect answer was not rewarded. Occasionally, the birds had the opportunity to pick the response that they were uncertain whether the screen was sparse or dense. In case pigeons picked this response they


received a small number of food pellets (smaller than for the correct answer). Researchers found that when given the choice of three responses in a discrimination test, correct, incorrect, and unsure, would often select the unsure response if the task was difficult. The notion of

unsure response in this case meant that pigeons did not

exactly know whether the response was absolutely correct or absolutely incorrect. It was either completely unknown to the pigeons so that they could not compare it with their experience or closely similar to either correct or incorrect option, but not totally coinciding. At first one might have thought that true thinking on human level was involved. Such conclusion could be drawn because if pigeons had trusted their inborn instincts and reflexes only, they would never have picked the unsure variant. However, when the unsure option was removed, performance upon the test did not improve, suggesting that pigeons were perhaps using the unsure option indiscriminately and did not possess the ability to think about what they knew. Besides, it is also important to know that pigeons might have picked the unsure option simply because they knew that in this case they would still get reinforcement, and there was no “correct incorrect risk for them. So it was mostly survival instinct, and not the human-like track of thought.

Recall of Past Events

Another quality indicative of episodic memory is the ability to consciously recall past events. Research indicates that apes do indeed possess this human ability, as evidenced by one animal recalling where an object of interest had been hidden almost 16 hours after seeing the experimenter hide it and then taking the initiative to contact an uninvolved caregiver and lead


that individual to the object. Additionally, at the time of recall, the animal was in a completely different environment and given no cues to aid in even remembering that the event had occurred.

Babb and Crystal (2006) demonstrated the ability of rats to recall past events in combination with where and when” the events occurred. These animals were given access to locations that contained either

flavored food or non-flavored chow. One of the flavored foods was then devalued by overfeeding it to the rat to the point of satiation or pairing it with an aversive flavor such as lithium chloride. Results indicated that the rats avoided the devalued flavor while still seeking out the other flavors. The researchers concluded that the rats utilized episodic memory to recall the past events of aversion to one of the flavors and alter their behavior to seek out only the desirable flavors. Similar studies, which documented rats spending greater amounts of time exploring familiar objects than new ones, even when the locations of the objects were shifted, provide support for the notion that rats can recall the where and when” of past events.

However, another experiment shows that rats are not able to use their past experience to modify their present actions. In this experiment rats had to retrieve food after having been shown that in case of delay food from one side of the maze becomes degraded, while food from the other side stays edible. Even after extensive training rats continued to deliver food from both sides of the maze with little preference for the non-degraded side (Kart-Teke, De Souza Silva, Huston, & Dere, 2006).


Temporal Order Memory

A third characteristic of episodic memory is temporal order memory, or the ability to recall a specific sequence of events. Studies have demonstrated an interesting biological similarity among humans and animals in this regard. Research has demonstrated that humans, rats, and monkeys all possess the capability to remember a sequence of odors or objects after some elapsed time. Lesions to the portion of the brain called the medial prefrontal cortex have been shown to inhibit this ability in not only humans, but also non-human primates and rodents. However, these lesions do not alter the ability to recognize new or familiar objects. This research suggests that different areas of the brain are responsible for different types of memory and that humans and animals possess similarities in brain anatomy and function with regards to memory.

Eichenbaum, Fortin, Ergorul, Wright, and Agster (2005) explored this concept in depth in an experiment involving rats and a series of odors. Of particular interest to the researchers was the role of the hippocampus in temporal memory. Rats were presented with a series of odors comprised of various household scents. Afterwards, the rats were again presented with two of the odors and prompted to select the one that had occurred earlier in the initial sequence presentation. Different pairs of odors were presented with the prompt, some of which occurred two odors apart in the initial sequence and some that had occurred three odors apart. For example, researchers first presented the rats with odors A, B, C, D, and E. Then, they presented the rats with odors A and C (two odors apart) or odors A and D (three odors apart). Results indicated that normal rats were able to correctly identify which of the odors in the pair came first at least approximately 70% of the time. Interestingly, the rats exhibited greater accuracy when the pairs consisted of odors three or more positions apart in the initial sequence.


Once this first trial was completed, the researchers repeated the experiment with rats given lesions in the hippocampus area of the brain. Rats in the control group performed equally well as their counterparts in the previous experiment; however, rats with hippocampal lesions had great difficulty in determining which odor had occurred first in the initial series. For example, normal rats correctly identified odor B as coming before odor E over 80% of the time. Rats with lesions could only correctly identify odor B as coming first less than 60% of the time, a percentage close to that of mere chance. Researchers concluded from these experiments that like humans, rats possess the ability to recall the sequence of events in an experience and the hippocampal portion of the brain governs that ability.

Retrospective and Prospective Memory

Episodic memory allows one to, in a sense, time travel to the past or future to either relive an event or predict a future event based upon past knowledge. This is referred to as retrospective and prospective memory, respectively. Like humans, research has indicated that some animals may be capable of these functions. Studies indicated that pigeons are able to anticipate future events based upon a recent set of actions. However, unlike humans who retain information for

decades, the retention intervals of pigeons are relatively short. For example, the pigeons successfully coped with a situation based on their previous experience. When that same situation was proposed to them a week later the pigeons acted as if they had never before dealt with it.


Evidence for retrospective memory has also been demonstrated in dolphins, non-human primates, and rats. This evidence showed itself through the same course of experiments, which were previously conducted on the pigeons. However, unlike humans who are able to use both retrospective and prospective memory in conjunction, these animals typically only use one or the other. In lab experiments, for example, rats associated chocolate with unpleasant experiences because once LiCl was added to it (retrospective memory). However, they never took into account the possibility that other types of food (bananas or grapes) may also be contaminated by LiCl in the future (prospective memory). Also, if prospective memory is used to complete a task, in animals it is linked with the near future, whereas humans have the ability to think much further ahead in time (Dere, Kart-Teke, Huston, & De Souza Silva, 2006).

Ferbinteanu and Shapiro (2003) investigated retrospective and prospective memory in rats and the role of the hippocampus in both types. Rats were placed in a wooden maze in which they were required to move from the start arm of the maze to the goal arm in order to gain a food reward. The location of the goal remained constant while the start location varied. Once the rat could reliably find the goal arm regardless of starting point, the goal location was changed. In the goal arms, retrospective memory was utilized to in recalling the different start arms; in the start arms, prospective memory guided the rat to the goal. Rats in the experimental group were then subject to fornix lesions or sham surgery to determine if the maze task required the functioning of the hippocampal region. While traversing the maze, quantitative measurements of brain electrical activity in various portions of the hippocampus were recorded. When comparing the performance and brain activity of these rats to control group rats, researchers found that different groups of hippocampal neurons fired when the rat utilized either retrospective or prospective memory to move through the maze. It was rather easy to identify for the reason that


groups of hippocampal neurons responsible for retrospective and prospective memory are situated in different parts of the brain. Additionally, retrospective memory was used more frequently than prospective. In rats with brain lesions, both forms of memory were diminished. Even though these rats remembered the tasks procedured and started them readily, their chances of successful completion were significantly smaller. On the other hand, the animals with sham lesions performed well after surgery, and their performance continued to improve. This research suggests the point that the neuronal signals in the various hippocampal areas were necessary for task performance.

These findings are in line with the knowledge concerning the role of the hippocampus in human episodic memory. In the experiment hippocampal neurons demonstrated prospective, place and retrospective coding. Therefore, the neurons appeared to encode memory demands and not a location or a specific sequence of movements through the maze. However, they provided a crucial signal for distinguishing the same events that happened in different moments of the time by encoding the recent past, the present and the near future simultaneously. Thus hippocampal neurons contribute to the mechanism of episodic memory.

Summary and Conclusions

Episodic memory is concerned with not only specific events in an organisms life, but also the where and when of their existence. Research in both humans and a variety of animals indicates that this type of memory is an overlapping feature. Animals have been shown to exhibit metacognition


rats, are able to utilize temporal order memory to recall a specific sequence of events. Retrospective memory, another component of episodic memory in humans, has been demonstrated in , non-human primates, and rats.

However, not all animals possess the capability for this type of memory; research indicated that pigeons were unable to demonstrate metacognition, an important component of episodic memory. In conjunction with studies involving tasks requiring memory, many research studies alter portions of the brain hypothesized to

play a central role, such as the hippocampus. The main idea of such research is that it is possible to influence memory not only in psychological (such as hypnosis) but also purely physical ways. It also explains the medical cases when after suffering a head trauma a person lost different memory functions (such as short-term memory or memorizing numbers). Results in this area indicate that the hippocampus plays a central role in episodic memory in humans and animals alike. Study of the similarities and differences between human and animal memory, particularly in the area of brain anatomy and function, may provide important insights into the evolution of memory across species and provide scientists with the explanation of memory mysteries both for animals and humans. In perspective, such research will also be important for developing treatments for different mental conditions directly connected with memory for example, amnesia or loss of short-term memory. Research results may be able to provide clues for treatment of such diseases from the choice of necessary medicine (after studying the influence


necessary surgical operations on certain parts of the brain.

References

Babb, S.J. & Crystal, J.D. (2006). Episodic-Like Memory in the Rat. Current Biology, 16, 1317-

1321.

Dere, E., Kart-Teke, E., Huston, J.P., & De Souza Silva, M.A. (2006). The Case for Episodic

Memory in Animals. Neuroscience and Biobehavioral Reviews. Retrieved November 24,

2006, from http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T0J-

4M7K9VY-

2&_user=10&_coverDate=10%2F31%2F2006&_rdoc=1&_fmt=summary&_orig=brows

e&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md

5=f357815279e7ff043b4d9cbcb85c80d0.

Eichenbaum, H., Fortin, N.J., Ergorul, C., Wright, S.P., & Agster, K.L. (2005). Episodic Recollection in Animals: If It Walks Like a Duck and Quacks Like a Duck…” Learning and Motivation, 36, 190-207.

Ferbinteanu, J. & Shapiro, M.L. (2003). Prospective and Retrospective Memory Coding in the

Hippocampus. Neuron, 40, 1227-1239.

Kart-Teke, E., De Souza Silva, M.A., Huston, J.P., & Dere, E. (2006). Wistar Rats Show

Episodic-Like Memory for Unique Experiences. Neurobiology of Learning and Memory,

85, 173-182.


Comparison Between Animals and Humans. Biological Psychology, 73, 3-18.