MEMORY ENCODING

Introduction

What is Memory Encoding? Memory Encoding is the initial learning of information. It is how the information coming from sensory input is changed into a form so it can be stored in the brain. Encoding is transforming internal thoughts and external events into short term and long-term memory. This is the process in which the information is processed and categorized for storage and retrieval. It is a crucial first step in creating a new memory. Memory encoding converts the perceived item or event into a construct that can be stored and recalled later from the brain.

For example, when we see a new object, such as a word, our retina sends the visual signal to the brain through the optic nerve. Then it goes through a lot of twists and turns before reaching temporal and parietal lobes. The job of these structures of the brain is to let the person knows that this information is a word. This journey of information is just the initial step which is known as memory encoding. The information has to go through this process so that it can be understood in a meaningful way. There are many types of encoding which we will discuss later in this article.

History

Herman Ebbinghaus

History of research on memory encoding starts with the person named Hermann Ebbinghaus (1850-1909). He was a pioneer in memory research. He studied learning and forgetting of things using himself as a subject. Ebbinghaus suggested the learning curve. He found that the new things associated with the prior knowledge were easier to recall.

During the 1900s, the research of Ivan Pavlov demonstrated the creation of a semantic relationship between unrelated things. Frederic Bartlett gave the ideal of mental schemas. He found that encoding was influenced by prior knowledge. Then came the Gestalt Theory which proposed that memory for encoding information was perceived as different from the stimuli, and it was also influenced by the context of stimuli.

In 1949, Donald Hebb proposed that the neurons that fire together wire together, which means that connections between neurons are made through repeated use. George Miller gave the idea that short term memory is limited to seven items, plus or minus two. The model of working memory was proposed by Alan Baddeley and Graham Hitch, in 1974. This model consists of the central executive, visuospatial sketchpad, and phonological loop as a method of processing and encoding. Baddeley added the episodic buffer into his model in 2000.

Types

There are many types of memory encoding, but the three main types are visual, acoustic, and semantic encoding. We will discuss all the types of encoding one by one.

Visual Encoding

Visual encoding is converting a visual image to understand it as an object. In this way, the visual information is converted to the memory stored in the brain. Visual information is stored in the visuospatial sketchpad which is connected to the central executive. The central executive is the key area of working memory. Before being encoded in long-term memory, this information is temporarily stored in iconic memory.

Acoustic Encoding

The encoding of auditory information is known as acoustic encoding. This is the process to understand the auditory aspects of an experience. It includes processing of sounds, words, and other auditory input for storage and retrieval. The phonological loop, which is a component of acoustic encoding, involves two different processes. First, acoustic information comes into the brain for one to two seconds. Second, rehearsal is required to convert it into long-term memory.

Semantic Encoding

Encoding of sensory input that has a particular meaning or context is known as semantic encoding. This may include remembering concepts, ideas, definitions, and dates, etc. Semantic encoding is easier to recall than the non-semantic or shallow encoding of things. Attaching emotions to information is a good idea to make semantic encoding much more memorable.

Elaborative Encoding

Elaborative encoding simply means relating new information to prior knowledge. Memory is a combination of old and new information about something. In other words, how we remember things depends on how we link it to prior information. Elaborative encoding of something has been shown to greatly enhance long-term memory.

Tactile Encoding

Tactile encoding is encoding and processing of feeling of touching something. Neurons in the somatosensory cortex play an important role in this process. Tactile encoding may include remembering the taste of a fruit, feeling of cuddling with your cat, or feeling of your first kiss. Processing of Odors can also be a part of the tactile encoding.

Organizational Encoding

Classifying information to a sequence of terms is what we know as organizational encoding. It includes categorization, listing, and grouping of information by noticing relationships among different items. Existing memories are encoded differently in organizational encoding.

Molecular basics

Interacting with a new thing triggers a cascade of molecular events. These molecular events lead to the formation of new memories. Changes that may occur at molecular level include;

  • Modification of synapses
  • Creation of new synapses
  • Modification of proteins
  • New protein synthesis
  • Activation of gene expression

According to some studies, high central nervous systems levels of acetylcholine aid in memory encoding during wakefulness. Whereas low levels of acetylcholine during sleep aid in proper consolidation of memories.

The ability of the brain to create or destroy neural synapses is termed as synaptic plasticity. Synaptic plasticity is the basis for learning. In learning experience, the reactions that are favored are reinforced and unfavorable reactions are weakened. So, the synaptic modifications can operate either way. In the short-term, synaptic changes may include modifications of pre-existing proteins leading to strengthening or weakening of a neural connection. In the long-term, entirely new synaptic connections may form.

Structures serving to encode

Different parts of the brain play role in encoding different kinds of information. For instance, visual information is processed in parietal and occipital cortices of the brain. Fusiform gyrus may also be involved in this. Superior temporal gyrus is involved in encoding the auditory stimulus.

The left prefrontal cortex and temporal regions are involved in semantic encoding. These structures can be activated by verbal and non-verbal stimuli. Other brain areas are also sometimes activated depending on what type of information it is.

Another part of the brain, the Medial temporal lobe (MTL) is also involved in semantic and perceptual encoding. It has been seen in studies that the medial temporal lobe is more activated in the case of non-verbal stimuli. It may also interact with other regions of the brain for the processing of specific things.

Hippocampus also plays an important role along with the frontal cortex in analyzing and determining sensory input.

Problems that affect encoding

Poor memory, whether in young people or adults, is sometimes the result of problems that affect the encoding process. Some of them are discussed here.

Sleep deprivation

In the case of sleep deprivation, the ability of the brain to encode new memories during daytime is impaired. Optimal sleep of 7-8 hours a day is recommended by the doctors which are necessary for the brain to work properly. Sleep deprivation may affect the encoding of both contextual and non-contextual aspects of memory. Slow-wave sleep also plays an important role in the consolidation of memories.

Depression

Depression is mainly associated with problems in the encoding of short-term memories. Depression and anxiety make it very difficult for a person to perceive and think clearly. Loss of focus and inability to make decisions due to depression is also linked to memory problems.

Alzheimer’s Disease

Alzheimer’s disease impairs the functioning of the ventral visual stream. Earlier visual areas are least compromised. The greatest compromise is in the later stages of visual encoding, which are done in fusiform and medial temporal lobe regions. The dysfunction of the medial temporal lobe in Alzheimer’s disease is indicated by the failure of MTL to discriminate between familiar and novel information.

Excessive multi-tasking

Students and young adults cannot focus on one thing when do excessive multi-tasking. This leads to a failure of memory encoding due to giving less attention to a specific task. Memory encoding demands focus, attention, and time and without these things, information is not processed and encoded properly.

Vitamin B-12 deficiency

Vitamin B-12 is necessary for healthy nerve cells and also red blood cells. When there is a deficiency of vitamin B-12, the nerve cells cannot work properly. In this way, its deficiency may cause a problem in memory encoding.

Drug abuse

Acute administration of drugs such as cocaine, nicotine, and alcohol may enhance hippocampus-dependent learning and memory. But the withdrawal of these drugs leads to significant disruptions in hippocampus activity. Opiates and cannabis disrupt memory and learning following acute administration, but their withdrawal is related to the enhancement of memory.

Encoding in Young Adults

The encoding process in a young adult is divided into five stages.

  1. Early perceptual processing
  2. The initial selection of information for processing in working memory
  3. Semantic and lexical processing
  4. Working memory update
  5. Elaborate processing

These stages are involved in both semantic and perceptual encoding but there are some differences between the two in different stages. In stage two, the processing of perceptual features is more readily elicited than semantic features. In stage three, there is more activity in the left interior region of the brain. These activities are thought to access semantic memory which is elicited by meaningful information.

Younger adults encode memories with relative ease. The processing speed, working memory, and ability to perceive things correctly is better in younger people. Brain activity has been seen at its peak in early life years and it declines in the later stages of life. That is why younger adults can learn and encode new information, the process which is affected in older people. 

Encoding in Old Adults

Older adults experience significant disturbances in encoding processes due to deficiencies in brain activities as compared to younger people. Older people may face difficulty with perceptual encoding and elaborative process of encoding. Differences between younger and older adults indicated that stage three of memory encoding is less efficient in older people, but no differences have been found in stage four.

The age difference is most prominent in stage five in which links are created between new and prior information. Older adults cannot encode information with elaboration. It is more challenging for older people to maintain information due to changes in the function of the frontal lobe. Perception and processing speed also decline with age.

There are some effective strategies for old learners to better encode new information. Older adults retain adequate powers of plasticity, but they must engage themselves in self-initiating processing. These strategies may lead them to achieve adequate memory encoding.

Genetics of Encoding

Genetics plays an important role in memory encoding. Human memory is known as a heritable trait. It is polygenic, which means that it is controlled by more than one gene. Many proteins are directly linked to a molecular cascade of reaction which leads to the formation of memory. Some of these proteins are encoded in the human by their genes. The memory capacity of humans is associated with variations in these genes. Genetic differences between individuals have been found responsible for round about 50% of the variance in memory tasks.

False Encoding and False Memories

False encoding is the processing of information in such a way that leads to the formation of false memories. The processes that lead to the formation of false memories may include self-referential encoding and construction of a gist trace. Perception and storage processes are also included in creating false memories during encoding.

False memories can also be created at the consolidation state. This usually happens due to post-event information and sleep. During sleep, reorganization and linking of memories with pre-existing representation takes place. This leads to the changing of memory representation that was originally encoded. Post-event information creates false memories due memory updating process.

False information is retrieved due to the activity of the hippocampus. Hippocampus equally retrieves true and false information. The hippocampus leads to the creation of false memories due to incorrect recombination.       

Tips for better Encoding

Here are some tips to make your brain better at encoding memory.

Mnemonics

Mnemonics may be short acronyms of all the first letters of things in a list or a peg-word system in which items to be remembered are associated with the words that a person can easily remember. Making mnemonics may be the best strategy to remember a list of things. An example of mnemonics is “Roy G Biv”, which is used to remember all the colors of the rainbow. But mnemonics do not help in encoding complex information.

Chunking

Chunking is a strategy in which information is organized into small and meaningful chunks. First, the information is divided into sections and then these sections are remembered as a unit. In this way, information becomes more meaningful and easier to digest. For example, people divide mobile numbers into small chunks like remembering a number as “15, 32, 454” instead of “1532454”.

Imagination

Imagination is associating images with words. This is a well-known strategy for the better encoding of information. Strong imagination leads to strong memory encoding. Using imagination creates long-lasting memories.

Association

When information is associated and organized into groups, there is a better chance of encoding true information. Associating new information with prior knowledge helps in better encoding and long-term memory.

Retrieval

Retrieval is one of the best strategies to encode information into long-term memory. This strategy includes retrieving information by creating and taking a test. Creating tests allows the information to be processed at a deeper level. Retrieval is way better than just repeating something over and over.

Spaced Learning

Spaced learning is spreading the study sessions. Information is encoded in a better way by using this technique. An example of spaced learning is studying something in five sessions of 10 minutes instead of studying it for continuous 50 minutes.

Drugs for Better Encoding

Some drugs act on specific acetylcholine receptors. Mimicking the effect of acetylcholine on these specific receptors by the drugs may lead to the creation and strengthening of neural connections. These drugs are still in the research process. Scientists say that some of these drugs have the potential to benefit the patients of Alzheimer’s disease. 

Summary

Memory encoding is a process by which the sensory information is modified and stored in the brain.

The three major types of memory encoding include visual encoding, acoustic encoding, and semantic encoding.

  • Visual encoding is concerned with visual inputs
  • Acoustic encoding is related to the audio inputs
  • Semantic encoding is associated with the concepts and ideas

Various molecular processes are involved in memory encoding such as the creation of new synapses, modification of the existing ones, synthesis of synaptic proteins, etc.

Encoding involves different areas of the brain as well as other body organs.

The memory encoding process may be affected by several reasons such as less sleep, anxiety, vitamin deficiency, drug abuse, etc.

Certain differences are seen in the encoding process of younger adults and older people. The memory encoding process is affected in old age due to several factors.

Sometimes, a false encoding of information may also occur leading to the formation of false memories.

Memory encoding can be improved by following some common tips advised by experts. Certain drugs may also aid the process of encoding in humans.

References

  1. Goldstien, E. Bruce (2015). Cognitive Psychology; Connecting the Mind, Research and Everyday Experience. Stamford, CT. USA: Cengage Learning. p. 122. ISBN 9781285763880.
  2. Ebbinghaus, H. (1885). Memory: A Contribution to Experimental Psychology.
  3. Bartlett, F. C. (1932). Remembering: A study in experimental and social psychology. Cambridge, England: Cambridge University Press.
  4. Baddeley, A., Eysenck, M.W., & Anderson, M.C. (2009). Memory. London: Psychology Press. p. 27, 44-59
  5. Parker, Amanda; Bussey, Timothy J.; Wilding, Edward L. (18 August 2005). The Cognitive Neuroscience of Memory: Encoding and Retrieval. Psychology Press. ISBN 978-1-135-43073-3.
  6. Sperling, G. (1963). A model for visual memory tasks. Human Factors, 5, 19-31.
  7. Kandel, E. (2004). The Molecular Biology of Memory Storage: A Dialog Between Genes and Synapses. Bioscience Reports, 24, 4-5.

Image sources:

  1. https://pixabay.com/illustrations/brain-mind-obsession-work-activity-954823/
  2. https://commons.wikimedia.org/wiki/File:Ebbinghaus.jpg