Mechanisms of MemoryMechanisms of Memory

Memory as psychical function Memory as psychical function Memory function helps fixing of perceived information, Memory function helps fixing of perceived information,

keeping it in verbal form or as traces of percept stimuli and keeping it in verbal form or as traces of percept stimuli and recognizing of this information in proper time. Genetic recognizing of this information in proper time. Genetic memory keeps information about body structure and forms memory keeps information about body structure and forms of its behavior. Biological memory is presented in both of its behavior. Biological memory is presented in both philogenetic and ontogenetic forms. The immune memory philogenetic and ontogenetic forms. The immune memory and psychical memory for instance, belong to ontogenetic and psychical memory for instance, belong to ontogenetic memory. memory.

General characteristics of memory are duration, strength of General characteristics of memory are duration, strength of keeping the information and exactness of its recognizing. In keeping the information and exactness of its recognizing. In man mechanisms of perception and keeping the information man mechanisms of perception and keeping the information are developed better, comparing to other mammalians. are developed better, comparing to other mammalians.

According to duration is concerned short-time and long-time According to duration is concerned short-time and long-time memory; in relation to kind of information – sensory and memory; in relation to kind of information – sensory and logic.logic.

Nerve substrate of memory Nerve substrate of memory

It’s discovered the nervous substrate of long-term It’s discovered the nervous substrate of long-term memory is mostly cerebral cortex. The most memory is mostly cerebral cortex. The most important regions are temporal lobes, prefrontal area important regions are temporal lobes, prefrontal area and hippocampus. Experimental researches revealed and hippocampus. Experimental researches revealed that some thalamic nuclei and reticular formation take that some thalamic nuclei and reticular formation take part in memory function. part in memory function.

Reticular formation gives ascending stimulatory Reticular formation gives ascending stimulatory influences to cerebral cortex, which help in keeping influences to cerebral cortex, which help in keeping awake condition of cortex and provides voluntary awake condition of cortex and provides voluntary attention. attention.

Levels of processingLevels of processing

Processing a word deeply—by its meaning (semantic encoding)—produces better recognition of it at a latertime than does shallow processing by attending to its appearance or sound.

Physiological mechanisms of memoryPhysiological mechanisms of memory At the molecular level, the habitation effect in the sensory At the molecular level, the habitation effect in the sensory

terminal results from progressive closure of calcium channels terminal results from progressive closure of calcium channels through the presynaptic terminal membrane. through the presynaptic terminal membrane.

In case of facilitation, the molecular mechanism is believed to be In case of facilitation, the molecular mechanism is believed to be following. Facilitated synapse releases serotonin that activates following. Facilitated synapse releases serotonin that activates adenylyl cyclase in postsynaptic cell. Then cyclic AMP activates adenylyl cyclase in postsynaptic cell. Then cyclic AMP activates proteinkinase that then causes phosphorylation of proteins. This proteinkinase that then causes phosphorylation of proteins. This blocks potassium channels for minutes or even weeks. Lack of blocks potassium channels for minutes or even weeks. Lack of potassium causes prolonged action potential in the presynaptic potassium causes prolonged action potential in the presynaptic terminal that leads to activation of calcium pores, allowing terminal that leads to activation of calcium pores, allowing tremendous quantities of calcium ions to enter the sensory tremendous quantities of calcium ions to enter the sensory terminal. This causes greatly increased transmitter release, terminal. This causes greatly increased transmitter release, thereby markedly facilitating synaptic transmission. thereby markedly facilitating synaptic transmission.

Thus in a very indirect way, the associative effect of stimulation Thus in a very indirect way, the associative effect of stimulation the facilitator neuron at the same time that the sensory neuron is the facilitator neuron at the same time that the sensory neuron is stimulated causes prolonged increase in excitatory sensitivity of stimulated causes prolonged increase in excitatory sensitivity of the sensory terminal, and this establishes the memory trace.the sensory terminal, and this establishes the memory trace.

Sensory Memory

Information first enters the memory system through the senses. We register and briefly store visual images via iconic memory and sounds via echoic memory.

As information enters the memory system through our senses, we briefly register and store visual images via iconic memory, in which picture images last no more than a few tenths of a second. We register and store sounds via echoic memory, where echoes of auditory stimuli may linger as long as 3 or 4 seconds.

Working/Short-Term Memory

At any given time, we can focus on and process only about seven items of information (either new or retrieved from our memory store). Without rehearsal, information disappears from short-term memory within seconds. Our capacity for storing information permanently in long-term memory is essentially unlimited.

Our short-term memory span for information just presented is limited—a seconds-long retention of up to about seven items, depending on the information and how it is presented. Our capacity for storing information permanently in long-term

memory is essentially unlimited.

Short term memoryShort term memory Eric Kandel showed initially that weaker stimuli give rise to a Eric Kandel showed initially that weaker stimuli give rise to a

form of short term memory, which lasts from minutes to form of short term memory, which lasts from minutes to hours. The mechanism for this "short term memory" is that hours. The mechanism for this "short term memory" is that particular ion channels are affected in such a manner that particular ion channels are affected in such a manner that more calcium ions will enter the nerve terminal. more calcium ions will enter the nerve terminal.

This leads to an increased amount of transmitter release at the This leads to an increased amount of transmitter release at the synapse, and thereby to an amplification of the reflex. This synapse, and thereby to an amplification of the reflex. This change is due to a phosphorylation of certain ion channel change is due to a phosphorylation of certain ion channel proteins, that is utilizing the molecular mechanism described proteins, that is utilizing the molecular mechanism described by Paul Greengard. by Paul Greengard.

Sperling’s classic experiments on the duration of visual Sperling’s classic experiments on the duration of visual sensory memory simulate sensory memory simulate Iconic MemoryIconic Memory. You will see nine . You will see nine random letters flashed in a 3 x 3 matrix, and will attempt to random letters flashed in a 3 x 3 matrix, and will attempt to recall the letters under three conditions: free-recall, cued-recall the letters under three conditions: free-recall, cued-recall, and delayed cued-recall. Your results will be compared recall, and delayed cued-recall. Your results will be compared to Sperling’s finding of rapid decay of the visual “icon.”to Sperling’s finding of rapid decay of the visual “icon.”

Short-term memory decayShort-term memory decay

Unless Unless rehearsed, rehearsed, verbal verbal information information may be quickly may be quickly forgotten. forgotten.

Long-Term Memory

Reticular formation gives ascending stimulatory influences to cerebral cortex, which help in keeping awake condition of cortex and provides voluntary attention.

At the molecular level, the habitation effect in the sensory terminal results from progressive closure of calcium channels through the presynaptic terminal membrane.

Storing Memories in the Brain

Researchers are exploring memory-related changes within and between single neurons. Long-term potentiation (LTP) appears to be the neural basis of learning and memory. Stress triggers hormonal changes that arouse brain areas and can produce indelible memories. We are particularly likely to remember vivid events that form flashbulb memories. We have two memory systems.

Explicit (declarative) memories of general knowledge, facts, and experiences are processed by the hippocampus. Implicit (nondeclarative) memories of skills and conditioned responses are processed by other parts of the brain, including the cerebellum.

Thinking process as psychical functionThinking process as psychical function The prefrontal association area is essential to carrying out thought The prefrontal association area is essential to carrying out thought

processes in the mind. This presumably results from some of the processes in the mind. This presumably results from some of the same capabilities of the prefrontal cortex that allow it to plan same capabilities of the prefrontal cortex that allow it to plan motor activities. motor activities.

The prefrontal association area is frequently described as The prefrontal association area is frequently described as important for elaboration of thoughts to store on a short-term important for elaboration of thoughts to store on a short-term basis “working memories” that are used to analyze each new basis “working memories” that are used to analyze each new thought while it is entering the braine. The somatic, visual, and thought while it is entering the braine. The somatic, visual, and auditory association areas all meet one another in the posterior auditory association areas all meet one another in the posterior part of the superior temporal lobe. This area is especially highly part of the superior temporal lobe. This area is especially highly developed in the dominant side of the brain – the left side in developed in the dominant side of the brain – the left side in almost all right-handed people. almost all right-handed people.

It plays the greatest single role of any part of cerebral cortex in the It plays the greatest single role of any part of cerebral cortex in the higher comprehensive levels of brain function that we call higher comprehensive levels of brain function that we call intelligence. This zone is also called general interpretative area, intelligence. This zone is also called general interpretative area, the gnostic area, the knowing area, tertiary association area. It is the gnostic area, the knowing area, tertiary association area. It is best known as Wernike’s area in honor of the neurologist who best known as Wernike’s area in honor of the neurologist who first describes it. first describes it.

Long term memoryLong term memory A more powerful and long lasting stimulus will result in a A more powerful and long lasting stimulus will result in a

form of long term memory that can remain for weeks. The form of long term memory that can remain for weeks. The stronger stimulus will give rise to increased levels of the stronger stimulus will give rise to increased levels of the messenger molecule cAMP and thereby protein kinase A. messenger molecule cAMP and thereby protein kinase A. These signals will reach the cell nucleus and cause a change These signals will reach the cell nucleus and cause a change in a number of proteins in the synapse. The formation of in a number of proteins in the synapse. The formation of certain proteins will increase, while others will decrease. The certain proteins will increase, while others will decrease. The final result is that the shape of the synapse can increase and final result is that the shape of the synapse can increase and thereby create a long lasting increase of synaptic function. thereby create a long lasting increase of synaptic function.

In contrast to short term memory, long term memory In contrast to short term memory, long term memory requires that new proteins are formed. If this synthesis of requires that new proteins are formed. If this synthesis of new proteins is prevented, the long term memory will be new proteins is prevented, the long term memory will be blocked but not the short term memory.blocked but not the short term memory.

Studying Memory: Information-Processing

A model of how memory works can help us think about how we form and retrieve memories. One model that has often been used is a computer’s informationprocessing system, which is in some ways similar to human memory.

To remember any event, we must get information into our brain (encoding), retain that information (storage), and later get it back out (retrieval).

How we form memories

1. We first record to-be-remembered information as a fleeting sensory memory.

2. From there, we process information into a short-term memory bin, where we encode it through rehearsal.

3. Finally, information moves into long-term memory for later retrieval.

Encoding: Getting Information In

Some information, such as the route you walked to your last class, you process with great ease, freeing your memory system to focus on less familiar events.

But to retain novel information, such as a friend’s new cellphone number, you need to pay attention and try hard.

Without conscious effort you automatically process information about:

• space. While studying, you often encode the place on a page where certain material appears; later, when struggling to recall that information, you may visualize its location.

• time. While going about your day, you unintentionally note the sequence of the day’s events. Later, when you realize you’ve left your coat somewhere, you can recreate that sequence and retrace your steps.

• frequency. You effortlessly keep track of how many times things happen, thus enabling you to realize “this is the third time I’ve run into her today.”

• well-learned information. For example, when you see words in your native language, perhaps on the side of a delivery truck, you cannot help but register their meanings. At such times, automatic processing is so effortless that it is difficult to shut it off.

Effortful Processing

We encode and retain vast amounts of information automatically, but we remember other types of information, such as this chapter’s concepts, only with effort and attention. Effortful processing often produces durable and accessible memories.

When learning novel information such as names, we can boost our memory through rehearsal, or conscious repetition.

How We Encode

Some types of information, notably information concerning space, time, and frequency, we encode mostly automatically. Other types of information, including much of our processing of meaning, imagery, and organization, require effort.

Mnemonic devices depend on the memorability of visual images and of information that is organized into chunks. Organizing information into chunks and hierarchies also aids memory.

What We Encode

When processing verbal information for storage, we usually encode its meaning, associating it with what we already know or imagine. Whether we hear eye-screem as “ice cream” or “I scream” depends on how the context and our experience guide us to interpret and encode the sounds.

Visual encoding (of images) and acoustic encoding (of sounds) engage shallower processing than semantic encoding (of meaning). We process verbal information best when we make it relevant to ourselves (the self-reference effect).

Storage: Retaining Information

When people develop expertise in an area, they process information not only in chunks but also in hierarchies composed of a few broad concepts divided and subdivided into narrower concepts and facts.

Organizing knowledge in hierarchies helps us retrieve information efficiently.

Effects of chunking on memoryEffects of chunking on memory

When we When we organize organize information information into meaningful into meaningful units, such as units, such as letters, words, letters, words, and phrases, we and phrases, we recall it more recall it more easily.easily.

Organization benefits memoryOrganization benefits memory

When we organize words or concepts into hierarchical groups, When we organize words or concepts into hierarchical groups, as illustrated here with concepts in this chapter, we remember as illustrated here with concepts in this chapter, we remember them better than when we see them presented randomly.them better than when we see them presented randomly.

Retrieval: Getting Information Out

Recall is the ability to retrieve information not in conscious awareness; a fill-in-the-blank question tests recall. Recognition is the ability to identify items previously learned; a multiplechoice question tests recognition. Relearning is the ability to master previously stored information more quickly than you originally learned it.

Retrieval cues catch our attention and tweak our web of associations, helping to move target information into conscious awareness. Priming is the process of activating associations (often unconsciously).

Retrieval Cues

To be remembered, information must be encoded, stored, and then retrieved. Memory is recall, recognition, and relearning. With the aid of associations (cues) that prime the memory, we retrieve the information we want to remember.

Cues sometimes come from returning to the original context. We use our senses as cues-a taste, smell, or sight may evoke us to recall a memory. Mood affects memory, too. While in a good or bad mood, we tend to retrieve memories congruent with that mood.

Forgetting

We may fail to encode information for entry into our memory system. Memories may fade after storage—rapidly at first, and then leveling off, a trend known as the forgetting curve.

We may experience retrieval failure, when old and new material compete, when we don’t have adequate retrieval cues, or possibly, in rare instances, because of motivated forgetting, or repression. In proactive interference, something learned in the past interferes with our ability to recall something recently learned. In retroactive interference, something recently learned interferes with something learned in the past.

Psychologists now tend to agree that: (1) Abuse happens, and can leave lasting scars. (2) Some innocent people have been falsely convicted of abuse

that never happened, and some true abusers have used the controversy over recovered memories to avoid punishment.

(3) Forgetting isolated past events, good or bad, is an ordinary part of life.

(4) Recovering good and bad memories, triggered by some memory cue, is commonplace.

(5) Infantile amnesia—the inability to recall memories from the first three years of life—makes recovery of very early childhood memories unlikely.

(6) Memories obtained under the influence of hypnosis or drugs or therapy are unreliable.

(7) Both real and false memories cause stress and suffering.

Three sins of forgetting

Absent-mindedness—inattention to details leads to encoding failure (our mind is elsewhere as we lay down the car keys).

Transience—storage decay over time (after we part ways with former classmates, unused information fades).

Blocking—inaccessibility of stored information (seeing an actor in an old movie, we feel the name on the tip of our tongue but experience retrieval failure—we cannot get it out).

Three sins of distortion

Misattribution—confusing the source of information (putting words in someone else’s mouth or remembering a dream as an actual happening).

Suggestibility—the lingering effects of misinformation (a leading question—“Did Mr. Jones touch your private parts?”—later becomes a young child’s false memory).

Bias—belief-colored recollections (current feelings toward a friend may color our recalled initial feelings).