Memory

Paul Broca : From Phrenology to Localization

Paul Broca 1861

Association Cortices

Three association areas—the prefrontal, parietal temporal occipital, and limbic—are involved in cognitive behavior planning, thinking, feeling, perception, speech, learning, memory, emotion, and skilled movements.

Penfield on one occasion electrical stimulation of the temporal lobes produced what he called an experiential response —a coherent recollection of an earlier experienceBut all of the patients Penfield studied had epileptic seizure foci in the temporal lobe, and the sites most effective in eliciting experiential responses were near those foci.

The medial temporal lobe and memory storage

More convincing evidence that the temporal lobes are important in memory emerged in the mid 1950s from the study of patients who had undergone bilateral removal of the hippocampus and neighboring regions in the temporal lobe as treatment for epilepsy (Brenda Milner)

The Distinction Between Explicit and Implicit Memory

Priming

Multi-store (Atkinson-Shiffrin memory model 1968)

Sensory Memory

Short Term Memory

The Percentage of Information Maintained in the Short-Term Store Over 18 Seconds (Fernald, 1997, p. 237).

The working memory model (Baddeley and Hitch 1974)

Working Memory Is a Short-Term Memory Required for Both the Encoding and Recall of Explicit Knowledge

Consolidation of Memory

Rehearsal Enhances the Transference of Short-Term Memory into Long-Term Memory

New Memories Are Codified During Consolidation

Similar types of information are pulled from the memory storage bins and used to help process the new information.

The new and old are compared for similarities and differences, and part of the storage process is to store the information about these similarities and differences, rather than to store the new information unprocessed.

Thus, during consolidation, the new memories are not stored randomly in the brain but are stored in direct association with other memories of the same type.

This is necessary if one is to be able to “search” the memory store at a later date to find the required information.

How Much Information Can We Remember?

Structural Changes Occur in Synapses During the Development of Long-Term Memory

1. Increase in vesicle release sites for secretion of transmitter substance.

2. Increase in number of transmitter vesicles released.

3. Increase in number of presynaptic terminals.

4. Changes in structures of the dendritic spines that permit transmission of stronger signals.

Long Term Memory

Characteristics of Long-Term Memory

Hippocampus is the seat of Consolidation

The anatomical organization of the hippocampal formation.

The role of the hippocampus in memory

The Long-Term Storage of Information

Explicit Memory Is Stored in Association Cortices

Semantic (Factual) Knowledge Is Stored in a Distributed Fashion in the Neocortex

Selective lesions in the posterior parietal cortex produce selective defects in semantic knowledge

Face recognition is from posterior temporal cortex

Neural correlates of category-specific knowledge

Episodic (Autobiographical) Knowledge About Time and Place Seems to Involve the Prefrontal Cortex

Source amnesia. : the ability to associate a piece of information with the time and place it was acquired is at the core of how accurately we remember the individual episodes of our lives, a deficit in source information interferes dramatically with the accuracy of recall of episodic knowledge

Explicit Knowledge Involves at Least Four Distinct Processes

1. Encoding

2. Consolidation

3. Storage

4. Retrieval

The Importance of Association in Information Storage

Implicit Memory Is Stored in Perceptual, Motor, and Emotional Circuits

Certain Forms of Implicit Memory Involve the Cerebellum

Emotional Memory stored in Amygdale

Savant Syndrome

usually diagnosed as severely retarded individuals

special talent may be in calculation, history, art, language, ormusic—are

Memory Aging and Brain Size

Forgetting

Alzheimer's Disease

Tip of the Tongue (TOT)

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