Lecturer: Dr. Benjamin Amponsah, Dept. of Psychology, UG, Legon - - PowerPoint PPT Presentation

College of Education School of Continuing and Distance Education

2014/2015 – 2016/2017

Lecturer: Dr. Benjamin Amponsah, Dept. of Psychology, UG, Legon Contact Information: bamponsah@ug.edu.gh

Session Overview

• We introduce yet another process of memory –
• storage. Presumably, that is where the encoded

information is stored in memory. We will look at the concept of storage and proceed to look at early attempts to locate the engram (the record left in memory by an experience). We will examine neuropsychological evidence of memory as well.

Slide 2

Session Objectives

• Appreciate the historical attempts to locate the

engram

• Examine the evidence from anterograde amnesia
• Review neuropsychological literature concerning the

location for storage of information

Slide 3

Session Outline

The key topics to be covered in the session are as follows:

• Topic One: Historical Attempts to Locate the Engram
• Topic Two: Evidence from Anterograde Amnesia
• Topic Three: Neuropsychological evidence

Slide 4

Reading List

• Ashcraft, M. H. (2006). Cognition (4th edn.), London: Pearson

Education Int.

• Galotti, K. M. (2004). Cognitive Psychology: In and out of the

laboratory (3rd Edn.). Belmont, CA: Wadsworth.

• Hunt, R. R. & Ellis, H. C. (1999). Fundamentals of Cognitive

Psychology (6th edn.), New York: McGraw-Hill.

• Willingham, D, B. (2001). Cognition: The thinking animal. NJ:

Prentice-Hall.

Slide 5

HISTORICAL ATTEMPTS TO LOCATE THE ENGRAM

Topic One

Slide 6

What is Storage?

• What is Storage?

– By storage, we are referring to the tendency to think that our memory is a vast warehouse into which we put or store things. – This is a metaphor, because physical traces of our experience cannot be seen in our brain, nevertheless, we believe our brains make some kind of neurological copy of our experiences and this copy is retained for use whenever we need it.

Slide 7

What is Storage?

• To complete the metaphor, it is also reasonable to

believe that when we are remembering something, we direct some part of our brain to look for the neurological copy.

• Brain Writing describes the idea that the brain makes a

physical trace of our experiences (Dennett, 1981).

Slide 8

What is Storage?

• Researchers make a comparison between brain storage and

computer storage. For example, if I store a picture on my computer, it leaves a physical trace in terms of codes when the information is saved.

• With appropriate cues (file name etc.) the computer can “re-

experience” this information when the appropriate cues are reinstated.

• The same process is experienced when we consider human

information processing. When we encode, we store the information and with appropriate cues we retrieve the information.

Slide 9

Some Early Experimental Work

• The Experimental Work of Karl Lashley
• Karl Lashley, a zoologist born in 1890 studied in John Hopkins

University in 1914. He studied there with J. B. Watson whose research on learning developed from the ideas of Ivan Pavlov – the classical conditionist.

• Pavlov produced a fairly specific notion of the neurological

changes underpinning learning and believed that learning was accompanied by certain structural changes in the brain.

• Parts of the brain that had not communicated neurally prior to

learning were associated (coupled) during learning and this association took the form of a physical, neural connection.

Slide 10

An outline of the Structure of Neuron

Representation of Good and Poor Memory

Lashley’s Effort to Locate the Engram

• Once the association is formed, it could not be

decoupled; but the association depended upon the continued integrity of the neural connection.

• If the connections were destroyed by accident or

disease, whatever had been learned through the association would be lost.

• How did Lashley prove this theory?
• First, he trained rats to run one of a set of mazes

with different levels of difficulty from easy to hard.

Slide 13

Lashley’s Effort to Locate the Engram

• After the rats became proficient in running the

mazes, he systematically cut the cortex (outer layer of the brain) of each rat; the cuts were made in different locations in each rat’s brain.

• Lashleys assumption was that by such cuts, there

should be interruption in the critical connections in the rats’ brains, and that the rats will show memory deficits on running the mazes.

Slide 14

Lashley’s Effort to Locate the Engram

• Lashleys expectations proved inaccurate. No matter

where the cut was made, the rats still excelled.

• Is it possible that he may have missed the critical

connections in every animal? This seems remote.

• What is likely is his conclusion that learning and memory don’t

seem to involve specific connections in the brain.

• Lashley repeated the experiment by removing more brain

tissue of some of the rats as they run complicated mazes, but

• nce again the location from which the tissue was removed

proved irrelevant.

Slide 15

Lashley’s Effort to Locate the Engram

• At the end, the 30 year old search for the

engram as a reification entity proved unsuccessful and currently, the term engram is used as a biological metaphor for what must in principle exist somewhere in the brain.

Slide 16

Principles of Brain Organization

• Lashley formulated two principles of brain organization:

 Mass Action - “The efficiency of performance of an entire complex function may be reduced in proportion to the extent of brain injury”.

• Mass action means that the brain works en masse. If a

small amount of brain tissue is removed, the brain can cope; but if a lot is removed, deficits will occur.  Equipotentiality – means that all parts of the brain are created equal as far as learning and memory are

• concerned. No one part of the brain is more important

than the other for memory storage.

Slide 17

Principles of Brain Organization

• We are not assuming that the location of damage in the

brain is unimportant. A relatively small amount of damage to language or to vision centres can produce an irretrievable disability.

• In other words, the principle of equipotentialilty may

be true for humans up to a certain point because certain specialization within the brain also exist. If these areas are destroyed in an adult, complete recovery is almost impossible.

Slide 18

MEMORY STORAGE EVIDENCE FROM ANTEROGRADE AMNESIA

Topic Two

Slide 19

Studies of Anterograde Amnesia

– Karl Lashley’s approach to the understanding of memory storage was basically from experimental point of view. – His efforts failed to find any trace of memories in specific cerebral locations. In other experimental research (e.g., Mishkin, 1978) determined that various subcortical structures including the amygdala, thalamus and the hippocampus have been associated with memory loss in monkeys.

Slide 20

Subcortical structures of a cross-section of the human brain implicated for memory function

The Case of HM

• One often cited evidence by (Milner, 1959) is the study of

H.M. (referred to this way to protect his privacy) who developed an incapacitating form of epilepsy, which was intractable to all forms of treatment, including the anti-epileptic drugs then in use.

• His neurosurgeon William Beecher Stover (1953) performed

surgery on him at the age of 27. Before the operation, H.M. was of normal intelligence, Stover removed many structures

• n the inner sector of the temporal lobes of both sides of

H.M.’s brain, including most of the hippocampus, the amygdala and some adjacent areas.

Slide 22

The Case of HM

• This noticeably reduced H.M.’s seizures and his

postoperative IQ actually rose about 10 points (Schacter, 1996).

• However, a severe impairment resulted and he

showed an inability to remember anything that had happed since his hippocampus was removed.

Slide 23

The Case of HM

• This form of memory loss is known as anterograde

amnesia (after; inability to encode events after trauma) and can be distinguished from retrograde amnesia (before; retrieval failure prior to trauma).

• H.M. showed little or no memory loss for events that

had taken place prior to the operation. His working memory was not impaired (Milner, 1959). However, if H.M. was distracted during any short-term memory task, his performance was poor.

Slide 24

The Case of HM

• The following happened to H.M.

 The 29-year-old patient continued to give his age as 27 (two years after the operation).  Reported that the operation had just taken place.  His memory of events before the operation remained clear but could not form new long-term memories (anterograde amnesia).  When his parents moved to a new house a few blocks away, he could not remember the new address.

Slide 25

The Case of HM

 Month after month he read the same magazine over and

• ver again without finding it familiar.

 His STM was fairly normal but if you left him and return 15 minutes later, he acted like he had not seen you before.  His favourite uncle died years ago, but he suffered the same grief anew each time he was told of his uncle’s death.

• H.M. was institutionalized for good because his life had no

continuity.

Slide 26

Summary

• What we have learnt from his disability is that

although we are unable to locate a specific location of memory, the substructures such as amygdala, hippocampus etc., are all important determinants of what has been stored.

Slide 27

MEMORY STORAGE EVIDENCE FROM NEUROPSYCHOLGY

Topic Three

Slide 28

Neuropsychological Evidence

• Our discussion earlier on may have given the impression of

“stores” or “components” of memory, suggesting that memory were located in one place in the brain. Unfortunately, the picture emerging from neuropsychological literature is quiet different and much more complicated.

• PET scan studies give us more information about the neural

underpinnings of memory.

• In PET studies, patients are injected with a radioactive

compound, and then asked to lie still with their head in a doughnut-shaped scanner (Posner & Raichle, 1994). The scanner measures blood flow in different brain areas (rCBF). The idea is that when a particular area of the brain is being used in a cognitive activity, more blood flows to that area.

Slide 29

Positron Emission Tomography Scan of the Brain PET DEVICE for Scanning the brain

PET Study

• PET study results confirm many aspects of Baddley’s

model of working memory, that is, there are different patterns of activation for verbal working memory (localized primarily in the left frontal and left parietal lobes) versus spatial working memory (localized primarily in the right parietal, temporal and frontal lobes).

• Note Paivio’s (1971) studies on the dual-code position

which suggested that information is coded in the brain either visually or verbally.

Slide 31

PET Study

• These studies are consistent with each other suggesting

that subjects who have lesions (cortical damage) in the right temporal lobe show disability in visuospatial encoding, while subjects who experience lesions in the left temporal lobe have difficulty processing verbal information.

• Although the results are intriguing we are far from having

a complete picture of how the brain instantiates many of memory phenomena.

Slide 32

Difficulty in Locating the Storage

• Note. We are not sure which aspects of memory are

localized in one place in the brain and which are distributed across different cortical regions.

• It is also not clear what kind of basic neural processes

are involved in any one particular complex cognitive activity.

• This situation is captured explicitly by Tulving

(1995:751):

Slide 33

Difficulty in Locating the Storage

• “Memory is a biological abstraction. There is no place in

the brain that one could point at and say: Here is

• memory. There is no single activity or class of activities
• f the organism that could be identified with the concept

that the term denotes. There is no known molecular change that corresponds to memory, no behavioural response of a living organism that is memory. Yet the term memory encompasses all these changes and activities”. Tulving, 1995.

Slide 34

Final Views on Storage

• Final views about Storage
• It has become embarrassing to cognitive and

neuropsychologists who have been at a loss to determine how the brain records a physical trace of experience.

• Again, cognitive psychologists have been unable to agree that

such brain writing is even necessitated by their theories of memory.

• The ambiguity at both the empirical and conceptual levels

partially explains why storage is the unwanted stepchild of the memory literature as opposed to encoding and retrieval, which are less controversial areas of interest.

Slide 35

Sample Questions

• What is storage in memory research?
• How similar is brain writing to inputting information
• n a microchip computer?
• Describe Karl Lashley’s classic experiment to locate

the memory trace.

Slide 36

References

• Dennett, D. C. (1981). Brainstorms. Cambridge, MA:

MIT Press/Bradford Books.

• Mishkin, M. (1978). Memory in monkeys severely

impaired by combined but not by separate removal of amygdala and hippocampus, Nature, 273, 297-298.

• Milner, B. (1959). The memory defect in bilateral

hippocampus lesions. Psychiatric Research Reports, 11, 43-58.

Slide 37

References

• Posner, M. I., & Raichle, M. E. (1994). Images of mind.

New York: Scientific American Library.

• Paivio, A. (1971). Imagery and verbal processes. New

York: Holt, Rinehart & Winston.

• Schacter, D. L. (1996). Searching for memory: The

brain, the mind, and the past. New York: Basic Books.

• Tulving, E. (1995). Introduction to Section IV: Memory. In
• M. S. Gazzaniga (Ed.), The cognitive neurosciences

(pp. 751-753) Cambridge, MA: Bradford.

Slide 38