Memory

Memory gives you your sense of self and allows you to tie your past to your present. It allows you to be comfortable with familiar people and surroundings. Memory is the process by which information is encoded, stored, and retrieved. Encoding takes information from the outside world and reaches our senses in chemical or physical stimuli. Storage is information about the environments stimuli is taken and placed in the brain for later use. Retrieval is that later use that the brain calls upon information stored to help it overcome or perform tasks. sematic memory is one for facts and eposotic is one for events. Procedural memory is memory for a behavior that can be performed.
Storage and Retrieval happen throughout the brain. There are many different places of the brain that are active when think of a an object such as a basketball. The image is reconstructed, different parts of the brain recall its name, shape, function, the sound it makes when being dribbled and much more. Neurologist are only begging to understand the full scope of memory although a lot has been learned already.
Sensory memory holds information for 1/5th - 1/2 a second and the brain takes what is perceived important and discards what is not. In short sensory memory allows an individual to retain impressions of their sensory information after the stimuli has ceased. Sensory memory comes from our senses such as touch or taste. Sensory memory is important because if we touch something hot of taste something to sour, we can remember to stay away from those things. Iconic memory is the fastest decaying sensory memory in the visual field where the image is stored breifly then for a small duration then is gone. Echoic memory another sensory memory is the fastest decaying store of auditory information. Haptic memory if the sensory memory for touch that is stored for a brief period of time. Sensory memory is like a snapshot of your environment. Sensory memory cannot be prolonged through rehearsal, this means that we cannot increase our sensory memory through practice. Smell many be the closest linked to memory because the olfactory bulb and the olfactory cortex, where smell is processed, is separated by just 2 or 3 synapses to the hippocampus and amygdala, which are largely involved in memory. sensory memory is 12 units of information that decay quickly.
Short-term memory, active memory or working memory allows us to recall situations for 30-40 seconds. After 30-40 seconds information that is perceived important is transferred and stored into long term memory and the rest of that information is lost. This process can be increased through rehearsal or chunking. Chunking is the process that allows us to take a lot of information and group it together. For example, a 9 digit number can be put into groups of 3 so that when recalling the information only 3 meaningful things have to be recalled instead of a string of n=9 numbers. Short term memory is 7 units plus or minus 2.
Memory distortion in Alzheimer’s disease is a very common disorder found in older adults. Performance of patients with mild to moderate Alzheimer’s disease was compared with the performance of age matched healthy adults. Researchers concluded the study with findings that showed reduced short-term memory recall for Alzheimer’s patients. Episodic memory and semantic abilities deteriorate early in Alzheimer’s disease. Since the cognitive system includes interconnected and reciprocally influenced neuronal networks, one study hypothesized that stimulation of lexical-semantic abilities may benefit semantically structured episodic memory. They found that with Lexical-Semantic stimulation treatment may improve episodic memory in Alzheimer’s Disease patients. It could also be regarded as a clinical option to counteract the cognitive decline typical of the disease.
Long term memory is an important aspect of cognition and can be divided into three categories; encoding, storage, retrieval. The compactly is extremely large and indefinite. Memories in your long term memory last the length of your life time although connections to some memories may become week the less they are recalled into consciousness. So although memories may never disappear, the amount of connections disintegrate which makes the memory weak and hard to recall. Encoding of long term memories occurs in the cortex at the medial temporal lobe and damages to this area is known to cause anterograde amnesia. Theoretically long term memory has limitless capacity but not enough is know to say so for sure. Long-term memory encodes information semantically for storage, as researched by Baddeley. In vision, the information needs to enter working memory before it can be stored into long-term memory. This is evidenced by the fact that the speed with which information is stored into long-term memory is determined by the amount of information that can be fit, at each step, into visual working memory. In other words, the larger the capacity of working memory for certain stimuli, the faster will these materials be learned.
Some theories consider sleep to be an important factor in establishing well-organized long-term memories. Sleep plays a key function in the consolidation of new memories.
According to Tarnow's theory, long-term memories are stored in format (reminiscent of the Penfield & Rasmussen’s findings that electrical excitations of cortex give rise to experiences similar to dreams). During waking life an executive function interprets long-term memory consistent with reality checking (Tarnow 2003). Also, that the information stored in memory, no matter how it was learned, can affect performance on a particular task without the subject being aware that this memory is being used. Newly acquired declarative memory traces are believed to be reactivated during NonREM sleep to promote their hippocampo-neocortical transfer for long-term storage. Specifically new declarative memories are better remembered if recall follows Stage II non-rapid eye movement sleep. The reactivation of memories during sleep can lead to lasting synaptic changes within certain neural networks. It is the high spindle activity, low oscillation activity, and delta wave activity during NREM sleep that helps to contribute to declarative memory consolidation. In learning before sleep spindles are redistributed to neuronally active upstates within slow oscillations. Sleep spindles are thought to induce synaptic changes and thereby contributing to memory consolidation during sleep.
The theory that sleep benefits memory retention is not a new idea. It has been around since Ebbinghaus's experiment on forgetting in 1885. More recently studies have been done by Payne and colleagues and Holtz and colleagues. In Payne and colleague's experiment participants were randomly selected and split into two groups. Both groups were given semantically related or unrelated word pairs, but one group was given the information at 9am and the other group received theirs at 9pm. Participants were then tested on the word pairs at one of three intervals 30 minutes, 12 hours, or 24 hours later. It was found that participants who had a period of sleep between the learning and testing sessions did better on the memory tests. This information is similar to other results found by previous experiments by Jenkins and Dallenbach (1924). It has also been found that many domains of declarative memory are affected by sleep such as emotional memory, semantic memory, and direct encoding.
Holtz found that not only does sleep affect consolidation of declarative memories, but also procedural memories. In this experiment fifty adolescent participants were taught either word pairs (which represents declarative memory) and a finger taping task(procedural memory at one of two different times of day. What they found was that the procedural finger taping task was best encoded and remembered directly before sleep, but the declarative word pairs task was better remembered and encoded if learned at 3 in the afternoon.


Declarative memory (sometimes referred to as explicit memory) is one of two types of long-term human memory. Declarative memory refers to memories which can be consciously recalled such as facts and knowledge. Declarative memory's counterpart is known as non-declarative or procedural memory,

Episodic memory is the memory of autobiographical events (times, places, associated emotions and other contextual knowledge) that can be explicitly stated. It is the collection of past personal experiences that occurred at a particular time and place. For example, if you remember the party on your 6th birthday, this is an episodic memory. They allow you to figuratively travel back in time to remember the event that took place at that particular time and place.

Semantic memory refers to the memory of meanings, understanding, and other concept-based knowledge, and underlies the conscious recollection of factual information and general knowledge about the world. Semantic and episodic memory together make up the category of declarative memory, which is one of the two major divisions in memory. With the use of our semantic memory we can give meaning to otherwise meaningless words and sentences. We can learn about new concepts by applying our knowledge learned from things in the past.

Procedural memory is memory for the performance of particular types of action. Procedural memory guides the processes we perform and most frequently resides below the level of conscious awareness. When needed, procedural memories are automatically retrieved and utilized for the execution of the integrated procedures involved in both cognitive and motor skills, from tying shoes to flying an airplane to reading. Procedural memories are accessed and used without the need for conscious control or attention. Procedural memory is a type of long-term memory and, more specifically, a type of implicit memory. Procedural memory is created through "procedural learning" or, repeating a complex activity over and over again until all of the relevant neural systems work together to automatically produce the activity. Implicit procedural learning is essential to the development of any motor skill or cognitive activity.

Implicit memory is a type of memory in which previous experiences aid in the performance of a task without conscious awareness of these previous experiences. Evidence for implicit memory arises in priming, a process whereby subjects are measured by how they have improved their performance on tasks for which they have been subconsciously prepared. Implicit memory also leads to the illusion-of-truth effect, which suggests that subjects are more likely to rate as true those statements that they have already heard, regardless of their veracity.

Explicit memory is the conscious, intentional recollection of previous experiences and information. People use explicit memory throughout the day, such as remembering the time of an appointment or recollecting an event from years ago. Explicit memory involves conscious recollection, compared with implicit memory which is an unconscious, unintentional form of memory. Remembering a specific driving lesson is an example of explicit memory, while improved driving skill as a result of the lesson is an example of implicit memory.