Memory

The Case of H.M.

Figure 14.19 MRI scans of the normal and damaged hippocampusKlein/Thorne: Biological Psychology© 2007 by Worth Publishers

Changes since lobectomy

• Only one or two minor seizures per day• Reduced medication• IQ was slightly above average• Normal perceptual and motor abilities

• Serious problems with memory

• http://www.nytimes.com/2008/12/05/us/05hm.html?_r=1&pagewanted=1&em

Memory Tests

Memory tests he could not do as well as a normal person

• Digit Span + 1 Test

• Block-Tapping + 1 Test

This is why…

• Short-term memory was fine– STM stores a limited amount of information for

a limited amount of time (about 15 seconds)

• Long-term memory was compromised– LTM stores an unlimited amount of

information for an unlimited amount of time

Other Memory Tests

Figure 14.17 The mirror tracing taskKlein/Thorne: Biological Psychology© 2007 by Worth Publishers

Mirror-Drawing Test

Rotary-Pursuit Task

Declarative vs. Procedural memory

Declarative memory• Digit span• Block tapping

Procedural memory• Mirror drawing• Rotary pursuit

Explicit vs. Implicit memory

H. M.’s Memory Problems

• Mild retrograde amnesia– Events that happened before surgery; e.g.

where he went to elementary school

• Severe anterograde amnesia– Events that happened after surgery

Other Distinctions

Semantic memory• General facts• Information• E.g.

Episodic memory• Particular events or

experiences in one’s life

• E.g.

Figure 14.4 Types of long-term memory Klein/Thorne: Biological Psychology© 2007 by Worth Publishers

The Atkinson-Shiffrin Model

• Memory storage has three stages• Sensory register

– 0.5 to 1 second

• Short-term store– Duration depends on

• Rehearsal• Amount of information – distraction

• Long-term store– Permanent

The Atkinson-Shiffrin Model

• Interference– Retroactive interference– Proactive interference

Posttraumatic Amnesia

Normal

functioning

Retrograde amnesia

Blow to

the head

Anterograde amnesia

Normal

functioning

Consolidation

Converting short-term memory to long-term memory

Consolidation

• Hebb’s theory• An experience triggers activity in a circuit of

neurons in the central nervous system– Reverberation

• The circuit of neurons is called a “cell assembly”• Eventually, the neurons in the cell assembly

change (e.g., shape of terminal button, number of receptors)

• This causes memories to be now be stored in the long term

Consolidation

• If process is disrupted, then unable to permanently store new memory– ECT

• Problem with this theory: the period of retrograde amnesia can be for years

Role of the Hippocampus in Memory

Figure 2.23 The limbic system Klein/Thorne: Biological Psychology© 2007 by Worth Publishers

Role of the Hippocampus in Memory

• Hippocampus is part of the limbic system, in the forebrain

• The hippocampus is involved in storing new memories

Frontal and temporal lobes

• Frontal and temporal lobes are active during retrieval of memories

Other Parts of the Brain Associated with Memory

Amygdala

• Memories for frightening events

Figure 2.23 The limbic system Klein/Thorne: Biological Psychology© 2007 by Worth Publishers

Prefrontal cortex

• Long-term working memory

• Cooking Thanksgiving dinner

Figure 2.25 The cerebral cortex, dorsal and lateral views Klein/Thorne: Biological Psychology© 2007 by Worth Publishers

Cerebellum

• Learned movements

Why you should not cram when studying for exams

• protein phosphatase 1

Why you should not cram when studying for exams

• Notes

Dr. Elizabeth Loftus

Loftus (2003)

Discussion

Your memories of your past have a great influence on your sense of who you are as a unique person. Yet, as Elizabeth Loftus demonstrated, memories are easily altered or distorted. What implications does this have with regard to a person’s sense of self?

• What are the broader implications of Loftus’ findings?

• What are the limitations of Loftus’ findings?