Understanding Memory: A Multi-Store Model Perspective
Memory: A Complex Functional System
Memory is a complex functional system, organized in different levels, active by nature, and unfolds in time through a series of successive links.
Multi-Store Model Theory
Short-Term Memory (STM)
- There is no index to measure the ability of the STM.
- STM capacity depends on the type of task and the type of retrieval requested, not a fixed number.
- Retrieval rates influence the amount of information held in STM.
- These indices appear to be influenced by Long-Term Memory (LTM).
Key Processes in STM:
- Repetition: Maintains information in the short term, allows transfer of information to LTM. Interference with a distractor during repetition lowers yields.
- Encoding: Gives meaning to information to pass it to STM. For example, encoding a phone number “01273 874000” becomes “Oh, 1, two hundred seventy-three, 8, 7, four thousand.”
- Retrieval: Uses cues to facilitate retrieval from LTM.
Types of Working Memory Tasks
STM Tasks:
- Direct Digit Series: [3 2 5 7] -> 3 2 5 7
- Series of representative figures
Working Memory Tasks:
- Reverse Digit Series: [3 2 5 7] -> 7 5 2 3
- A series of figures in reverse order
- Generation of numbers or letters in random order
Classification of Memory
I. Implicit Memory (Undeclared)
Acquisition of knowledge without the ability to verbalize what has been learned in the process. Ability to solve problems or use sequential language without being able to explain what we have learned. It refers to feelings, skills, and abilities that are recalled unconsciously.
- Classical Conditioning: Basic emotional responses
- Procedural Memory
- Priming
Classical Conditioning
Applies to basic types of learning like the blink reflex, in that after a noise, a puff of air is blown into the subject’s eye, causing a blink. After repeated trials, the noise alone is sufficient for the occurrence of the blink. This type of response is integrated at the brainstem.
Basic Emotional Responses
The most studied is the emotional response to fear. When we are subjected to a noxious stimulus, for example, a puncture, your body reacts with an autonomic and behavioral response, which we call emotion. This response is innate and is integrated at the level of the hypothalamus. However, the contextual information in which the damage occurred is analyzed and learned by the amygdala. The amygdala may then recognize sensory stimuli that, although not harmful in themselves, can signify the next occurrence of a noxious stimulus. This anticipates the emotional response to injury.
Procedural Learning
It refers to the ability to develop skills and then implement them. The structures related to the learning of motor skills are the basal ganglia and cerebellum. The premotor cortex is involved in the execution of previously learned skills (praxia).
Priming
It refers to the ability to spontaneously recall information previously experienced, although not consciously remember their learning. For example, asking an amnesic patient to remember the word “cat,” then a few minutes later asking about the word and they do not remember, then asking them to read the first animal that pops into their mind and they say “cat.” This type of implicit learning has been linked to the parieto-temporo-occipital association cortex.
II. Explicit Memory (Declarative)
Is the type of memory that is consciously manifested through language. A prerequisite for the “storage” of explicit memory is the awareness and immediate processing of the material (repetition or association).
- Semantic Memory
- Episodic Memory
Historical Background of the Neurobiology of Memory
Dr. Wilder Penfield (1891-1976) – American Neurosurgeon. He founded the Montreal Neurological Institute.
Dr. Brenda Milner – University of Montreal (Canada), Canadian Neuropsychologist. A pioneer in applying the techniques of experimental psychology in a field dominated by clinical studies. She conducted many works about memory impairment in relation to injuries of the cerebral hemispheres and in-depth analysis of global amnesic syndrome.
Eric Kandel – Born in Vienna, Austria in 1929. U.S. citizen. He received his doctorate in medicine at the University of New York and his subsequent training is split between neurophysiology and psychiatry in Massachusetts, Harvard University, and Paris.
Neurobiological Basis of Memory
It was long thought that information was stored in the hippocampus. Current theories point out that the hippocampus is only a temporary storage site for long-term memory and that learned information would be transferred for final disposal to other areas of the cortex.
Theory:
The hippocampus is an intermediate station for long-term memory, or a clearing system that is essential for memory storage elsewhere in the brain.