late episodic memory (em) effects (and their possible association with weak memory traces)

Doreen Nessler, CEPL April, 2005

Late Episodic Memory (EM) effects

(and their possible associationwith weak memory traces)

Doreen Nessler David Friedman

Ray Johnson, Jr.

Michael Bersick

Letecia Latif

andAge-related effects


Post-retrieval processes(Allan et al., 1998; Mecklinger, 2000)

Monitoring and verification processes(Rugg et al., 2000)

AF3

OZ

CPZ

C1 C5 C3 C2 C4 C6

AF4

F1

FC1FC3FC5

F3 F5

CP1 CP3 CP5 TP7

F7

FT7

AF7 FP1 FPz

F2

FP2AF8

F4 F6 F8

FT8FC2 FC4 FC6

CP2 CP4CP6TP8

P1 P3 P5

CZ

FCZ

FZ

AFz

P2 PZ P4 P6 P7 P8

PO3 PO7

PO4 PO8

O1 O2

LM RM

POZ

Episodic memory (EM) effects

AF8500 1000 1500

right frontal EM effectHits

Correct Rejections

Retrieval success(Wilding & Rugg, 1996, 1997; Mecklinger & Meinshausen, 1998)

Retrieval effort/ Retrieval attempt(Trott, Friedman et al. 1999; Rugg, Otten, & Henson 2002)

Late


Late Parietal Negativity

Pz500 1000 1500

HitsCorrect Rejections

Late Episodic memory (EM) effects (2)

AF3

OZ

CPZ

C1 C5 C3 C2 C4 C6

AF4

F1

FC1FC3FC5

F3 F5

CP1 CP3 CP5 TP7

F7

FT7

AF7 FP1 FPz

F2

FP2AF8

F4 F6 F8

FT8FC2 FC4 FC6

CP2 CP4CP6TP8

P1 P3 P5

CZ

FCZ

FZ

AFz

P2 PZ P4 P6 P7 P8

PO3 PO7

PO4 PO8

O1 O2

LM RM

POZ

Response-related(Wilding & Rugg, 1997)

Sensory-specific source search and/or retrieval(Cycowicz, Friedman et al., 2001; Wegesin et al, 2002; Johansson et al., 2002)

Late parietal negativity can also reflect action monitoring(Johansson & Mecklinger, 2003)


Late Episodic memory (EM) effects (3)

Late EM effects signs of Re-encoding?

Late right frontal effect:post-retrieval processes

Late parietal negativity:retrieval of attribute conjunction, action monitoring


Aging andLate Episodic memory (EM) effects

Elderly no right frontal effect(Senkfor and VanPetten, 1996; Trott, Friedman et al., 1996, 1997; Wegesin et al. 2002)

Elderly with good memory performance show left frontal negativity(Fabiani, Friedman et. al. 1999, see Friedman, 2003)

10 μV

800 1600 2400

Frontal negativity

+

-

Left frontalelectrode

Young

Old LowOld High

Adapted from Friedman, 2003

Late parietal negativity stronger for the elderly than for the young(Trott, Friedman et al., 1997; Wegesin et al. 2002; Li, Morcom and Rugg, 2004)

Young and Elderly similar right frontal effects(Mark and Rugg, 1998; Li, Morcom and Rugg, 2004)

Age-related frontal lobe deficit

The eldery rely more on perceptual information

Successful compensation


Questions and Hypotheses

If late EM effects reflect post-retrieval processes that strengthen the memory trace they are expected to be smaller in a repetition of the recognition test.

2.) Late left frontal negativity for the elderly:reflection of compensation?

A late frontal negativity is expected for conditions that elicited similar recognition performance in the young and the elderly.

3.) Late EM effects:Re-encoding of items that were difficult to

recognize?

1.) Late parietal negativity:more prevalent in the data of the elderly?


Encoding High Selection

S1 500ms

ISI 500ms

Low Selection

heavyheavy

FEATHERFEATHER

old/new Recognition

300ms OLD: Low Selection

NEW

ACORNACORN

CATCAT

FEATHERFEATHEROLD: High Selection

S2 300msACORNACORN

match?

Paradigm

ACORNACORN

LS match LS no match

Repetition of concept


DesignEncoding 1

120 words 60 words High Selection 60 words Low Selection120 OLD words120 NEW words

Recognition 1

Repetition

Encoding 2

Second encoding for the120 words from Study 1

120 OLD words120 NEW words

Recognition 2


Participants

YOUNG(N=16)

ELDERLY (N=16)

Mean age22.8 (18 to

29)71.6 (62 to

86)

Female 11 7

Years of Education

15.9 15.9

Mini Mental Exam

55.6 54.1

Verbal IQ(WAIS III)

118 127

Pictorial IQ(WAIS III)

122 117


EEG Methods

62 sintered Ag/AgCl ElectrodesOffline re-referred to linked mastoidsRecording: DC - 100 Hz500 Hz sampling rate

AF3

OZ

CPZ

C1 C5 C3 C2

C4 C6

AF4

F1

FC1 FC3 FC5

F3 F5

CP1 CP3 CP5 TP7

F7

FT7

AF7

FP1 FPz

F2

FP2

AF8

F4 F6 F8

FT8 FC2 FC4 FC6

CP2 CP4 CP6 TP8

P1 P3 P5

CZ

FCZ

FZ

AFz

P2 PZ P4 P6 P7 P8

PO3 PO7

PO4 PO8

O1 O2

LM RM

POZ


Behavioral Results: RecognitionTest 1

73.483.2

63.157.3

78.5

41.8

0

10

20

30

40

50

60

70

80

90

100

High selection Low selectionmatch

Low selection no-match

corr

ecte

d h

it r

ates

Young

Elderly* *

n.s.


Correct rejectionHits, HS condition

Young Elderly

Recognition Test 1

Late parietal negativity

Late right frontal EM effect

High Selection

trend


Left frontalnegativity

Correct rejectionHits, LS match condition

Young Elderly

Recognition Test 1Low Selection match


Parietal negativity


Correct rejectionHits, LS no-match condition

Young Elderly

Parietal negativity


Recognition Test 1Low Selection no-match


Parietal negativity


Late EM effects for the young and the elderlyTest 1


91.489.3 85.279

0

10

20

30

40

50

60

70

80

90

100

HS LS

corr

ecte

d hit

rat

es

Behavioral Results: Recognition

73.483.2

63.157.3

78.5

41.8

0

10

20

30

40

50

60

70

80

90

100

High selection Low selectionmatch

Low selection no-match

corr

ecte

d h

it r

ates

Young

Elderly* *

n.s.Test 1

Test 2


Young Elderly

Correct rejectionHits, HS condition

Recognition Test 2High Selection



Recognition Test 2Low Selection

Correct rejectionHits, LS condition test 2

Young Elderly



Late EM effects for the young and the elderlyTest 2


Late frontal negativity does not always seem to reflectsuccessful compensation.

The elderly seem to post-process physical features,while the young seem to work more with abstract information.

Discussion

2.) Late left frontal negativity for the elderly:reflection of compensation?

3.) Late EM effects:Re-encoding of items that were difficult to

recognize?

1.) Late parietal negativity:more prevalent in the data of the elderly?

Late parietal negativity: Reflection of action monitoring?

Late EM effects seem to reflect re-encoding processes.


THANK YOU FOR YOUR ATTENTION!

Last Slide!

late episodic memory (em) effects (and their possible association with weak memory traces)

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