Memory: Introduction Zara A. Melikyan

Memory: Introduction

Zara A. Melikyan

(some slides are courtesy of Dr. G.P.Sutton)

February 5, 2015

Lecture Plan:

Memory: definition, subtypes and processes

Clinical examples of memory loss - patients H.M. & C.W.

What is memory loss

Memory: assessment

Example of progressive memory loss - Alzheimer’s dementia

Memory: Definition

Memory is the process in which information is:

-

encoded

- receiving, processing, combining information,

- stored - creation of permanent record of encoded information, - retrieved - calling back the stored information to use in activity

Temporal Memory Organization

Sensory Memory

- limited capacity 12 elements (G. Sperling), limited duration (hundreds of milliseconds). Registers all the sensory information.

- Iconic

- Echoic

- HapticShort-Term Memory - limited capacity (7+/-2, or 4-5 elements), limited duration (18-30 sec). Registers information to which attention is paid. Transient patterns of neuronal connection in prefrontal & temporal lobes, hippocampus essential for information consolidation from STM to LTM.

Information is rehearsed and chunked

Long-Term Memory

- close to unlimited capacity, unlimited duration. More stable and permanent changes in neuronal connections throughout the brain.

Memory Models

Atkinson-Shiffrin Model (1968)

Baddeley & Hitch Model of Working Memory (1974)

Types of Long-Term Memory

LTM

Declarative

Episodic

Semantic

Nondeclarative

(Procedural)

Skill learning

Priming

Conditioning

LTM:

Declarative vs. Nondeclarative

Declarative memory

- Memory that can be stated or described

- Capital of Italy

Nondeclarative (Procedural)

- Memory about perceptual/motor procedures

- Demonstrated via performance (not conscious recollection)

- Riding a bicycle

Declarative:

Episodic vs. Semantic

Episodic

- Detailed autobiographical memory

-15th birthday party

Semantic- Generalized declarative memory

- Facts and information acquired through learning

- Capital of Italy

Nondeclarative:

Skill Learning vs. Priming vs. Conditioning

Skill Learning

Learning how to perform a task by repeating a process

May include:

- Sensorymotor skills (mirror tracing)- Perceptual skills (reading mirror-reversed text)

- Cognitive skills (planning and problem-solving)

Nondeclarative:

Skill Learning vs. Priming vs. Conditioning

Priming

- Change in how you process a stimulus (e.g. word, picture) because you have seen it (or something similar) previously

- Does not require declarative memory (intact in H.M.)

Nondeclarative:

Skill Learning vs. Priming vs. Conditioning

Conditioning

Involves relationships between events

Associative learning

- Classical conditioning. Association is formed between two previously unrelated stimuli. Pavlov’s dogs.

-

Instrumental/operant conditioning

. Association is formed between behavior and cosenquences. Skinner box.

http://www.youtube.com/watch?v=TtfQlkGwE2U

Patient 1:

Henry Gustav Molaison (1926-2008)

The case of H.M. is widely studied and published on. Played important role in cognitive neuropsychology of memory;

Suffered intractable epilepsy: partial seizures, after 16y.o. tonic-clonic seizures;

Source of epileptic discharge - left and right medial temporal lobes;

1953 (27 y.o.) bilateral medial temporal lobe resection - hippocampi, amygdalae, enthorhinal cortex, anterolateral temporal cortex. Most structures were not functional;

Patient 1:

Henry Gustav Molaison (1926-2008)

After the surgery: epilepsy is controlled, severe memory impairment:

Severe anterograde amnesia

: explicit & semantic memory;

Moderate temporary-graded retrograde amnesia: could not remember most events 1-2 years prior and some events 11 years prior to surgery;Intact: working memory, procedural memory;

At the end of life: worked crossword puzzles, able to fill in answers to cues related to pre-surgery knowledge, able to modify old memories with new information;

Resided in care institute 1953-2008. Sliced brain in UCSD.

Patient 2:

Clive Wearing (born 1938)

Accomplished British musicologist, conductor, keyboardist;

In 1985 (47y.o.) contracted Herpesviral encephalitis (Herpes simplex virus) that attacked his CNS: hippocampus (transfers STM to LTM), frontal lobes;

Profound total amnesia:

- severe anterograde amnesia (unable to form new memories, his memory lasts 7-30 seconds),

-

moderate-severe retrograde amnesia

(cannot recall aspects of past memories, knows that he has children but does not remember their names, loves his second wife),

- unable to associate memories effectively,

- unable to control emotions (labile mood) (e.g. shakes spasmodically after music stops)

Intact: procedural memory (knows how to play the piano, conduct an orchestra);

Can learn new practices and very few new facts not from episodic memory but by procedural memory (e.g. after having watched a video multiple times he is able to anticipate parts of it).

http://www.youtube.com/watch?v=Lu9UY8Zqg-Q&feature=related

http://www.youtube.com/watch?v=xCyvzI2aVUo&feature=relmfu

https://www.youtube.com/watch?v=9BrCBq2FY_U

Memory Loss

Amnesia

, from Greek “a” - without, “mnemi" - memory

- Severe memory impairment

- Usually due to injury or disease

Retrograde amnesiaLoss of memories prior to an event. Disruption of memory consolidation

Anterograde amnesia

Inability to form new memories (e.g. H.M., C.W.)

Study of Memory

Tests:

-

Verbal

: word lists, paragraphs

- Visual: shapes, objects, scenes - Tactile, audial, memory for smellsLearning and immediate retrieval, delayed recall, recognitionRecency and Primacy Effects

Progressive Memory Loss: Alzheimer’s Dementia

Dementia

from Latin: “de” - to depart, “mens” - mind, being out of one's mind.

General term that describes a wide range of symptoms associated with a decline in mental ability severe enough to reduce a person's ability to perform everyday activities. These symptoms:

- Are not present since birth

- Are a change from previous baseline mental function

- Last more than six months

- Not associated with a loss/alteration of consciousness

- Not due to other medical conditions (e.g. depression)

- Progressive

Dementias have different etiologies: primary - organic brain degeneration (AD), secondary (TBI, infection, intoxication, etc.).

Dementia is very wide spread due to increased life expectancy and decreased birth: 2010 worldwide 35.6 million, in 2030 65.7 million, in 2050 115.4 million;

AD 50-75% of all types of dementia;

Associated with significant cost: lost jobs for patients and caregivers, medical supplies and drugs, home modification, care, nursing home

Progressive Memory Loss: Alzheimer’s Dementia

Alzheimer’s Dementia named after Aloysius (Alois) Alzheimer, a German psychiatrist and neuropathologist who identified the first case of the disease in 1906;

His patient Mrs. Auguste Dete, a 51 year old woman experiencing symptoms of memory loss, unusual behavioral changes, hallucinations, delusions, and impaired social functioning;

Post-mortem brain examination by Dr. Alzheimer revealed AD markers: amyloid plaques, neurofibrillary tangles, and arteriosclerotic alterations of brain matter.

Alzheimer’s Dementia: Symptoms

Symptoms worsen over time. Symptoms may vary but, at least two of the following mental functions must be significantly impaired:

Domain

Symptoms

Memory

First short-term memory: keeping track of purse, wallet, keys, paying bills, planning meals and cooking, remembering appointments, where car is parked, the route to home

Long-term memory: own biography, names and faces of family members

Abstraction, planning

Lose the ability to perform familiar tasks, plan activities, and draw simple conclusions from facts

Communication, language, comprehension

Inability to understand instructions, follow the logic of moderately complex sentences. Later: difficulty understanding own sentences, difficulty forming thoughts into words

Poor judgement

Do not recognize consequences of own actions, unable to evaluate appropriateness of behavior, level of risk. Behavior may become rude, overly friendly, aggressive. Personal hygiene may be ignored.

Impaired orientation

To time (date, time), place, person

Decreased attention, increased restlessness

Quickly begin activity, quickly loose interest/wander (safety problems)

Visual perception

Behavioral changes, psychosis

Loose interest in once-pleasurable activities, become passive, depressed (20-30%), anxious (20%). Delusions, suspicion, paranoia, hallucinations. Sleep disturbances: insomnia, sleep interruptions. Disinhibition, impulsivity, agitation, balance problems, tremor, troubles eating and swallowing, wondering and restlessness.

Thank you!