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Long-term Memory Assessment

Associate Professor Dr. Aamir Saeed Malik

Outline

• Introduction• Memory types• Memory Processes• Memory Model • Memory and Brain• Prefrontal and Medial Temporal Lobe• Memory Diseases• Long-term Memory Assessment• Existing Techniques• EEG Based Assessment • Summary• References

Introduction

• Memory?

– The ability of storing and retrieving of what has been learned or experienced.

Memory Types

Sensory Memory(< 1 sec)

Short-term (working Memory)

(20-30 sec)

Long-term Memory(life time)

Implicit Memory (unconscious)

Explicit Memory (conscious)

Procedural Memory (skills, tasks)

Declarative Memory

(facts, events)

Semantic Memory (facts, concepts)

Episodic Memory(events, experiences)

How to do things, like running, swimming

Memory Processes

The three main processes involved in human memory are therefore encoding, storage and recall (retrieval). Additionally, the process of memory consolidation (which can be considered to be either part of the encoding process or the storage process).

Memory Encoding: It allows the perceived information of interest to be converted into construct that can be stored within the brain, which cab later recalled.

Memory Storage: It allows to retain the encoded information in the brain.

Memory Retrieval/Recall: It refers to recollect the stored information from memory.

Memory and Brain

Memory and Brain

J. S. Simons and H. J. Spiers, "Prefrontal and medial temporal lobe interactions in long-term memory," Nature Reviews Neuroscience, vol. 4, pp. 637-648, 2003.

Role of Prefrontal and Temporal

Lobe

Memory Diseases

Memory disorders can range from mild to severe, but they

all result from some kind of neurological damage to the

structures of the brain, thus hindering the storage, retention

and recollection of memories.

Mild Cognitive Impairment

Vascular Dementia

Mixed Dementia

Parkinson’s Disease

Dementia with Lewy Bodies

Frontotemporal Dementia

http://www.cpmc.org/advanced/neurosciences/brainhealth/memory_causes.html

Memory Diseases

Alzheimer's is the most common form of dementia, a general term for memory loss and

other intellectual abilities serious enough to interfere with daily life

Memory Assessment

• Why Memory Assessment?

– To detect possible cognitive impairments

– To assess severity of cognitive impairments and memory loss

– To detect a patient needs further evaluation

Existing Techniques (1/2)

• Memory Assessment Scales (MAS)– Developed at three setting over 9 years: the University of

Vermont (1981-1983), Memphis State University (1984-1988), and Hahnemann University (1988-1990)

– MAS is based on manual and behavioural assessment – MAS is standardized for use with adults 18 to 90 years age – MAS assess three areas of Cognitive Functions

• Attention, concentration and short-term memory• Learning and Immediate memory• Memory following a delay

– MAS consists of 12 subtests, which are based on seven memory tasks

– MAS requires normative data (843 adults data collected)– MAS needs professional training in neuropsychology and

clinical psychology.

http://www.brainmetric.com/pdfs/MAS_Manual.pdf

Existing Techniques (2/2)

• Wide Range Assessment of Memory and Learning, 2nd Edition (WRAML2 kit)

– Developed by Pearson Education, Inc.

– Measures memory functioning and learning

– Age range 5 to 90 years

– Paper and pencil based administration and hand scoring

– One hour time required

– Price $615.00

http://www.pearsonclinical.com/psychology/products/100001702/wide-range-assessment-of-memory-and-learning-second-edition-wraml2.html

EEG Based Assessment

• First recorded by Hans Berger in 1929.

• EEG recordings are noninvasive, painless, do not interfere much with a human subject’s ability to move or perceive stimuli, are relatively low-cost.

• Electrodes measure voltage-differences at the scalp in the microvolt (μV) range.

• EEG provides insights of brain disorders including cognitive and memory impairments

EEG Frequencies

• EEG rhythms correlate with patterns of behavior (level of attentiveness, sleeping, waking, seizures, coma).

• Rhythms occur in distinct frequency ranges:

• Gamma: 20-60 Hz (“cognitive” frequency band)

• Beta: 14-20 Hz (activated cortex)

• Alpha: 8-13 Hz (quiet waking)

• Theta: 4-7 Hz (sleep stages)

• Delta: less than 4 Hz (sleep stages, especially “deep sleep”)

• Higher frequencies: active processing, relatively de-synchronized activity (alert wakefulness, dream sleep).

• Lower frequencies: strongly synchronized activity (nondreamingsleep, coma).

16

EEG Signal

17

Experimental Evidences for

Long-term Memory Assessment

using EEG

30

min

Experiment Design

1. RAPM Test (45 min)

2. EO, EC EEG (5min)

3. Study Contents (30 min)

4. Oddball Test (3 min)

5. Recall Test (10 min)

1. EO, EC EEG (5 min)

2. Recall Test (10 min)

3. Study Contents (10 min)

1. EO, EC EEG (5 min)

2. Recall Test (10 min)

3. Study Contents (10 min)

1. EO, EO EEG (5 min)

2. Recall Test (10 min)

1st

Sess

ion

2n

dSe

ssio

n3

rdSe

ssio

n4

thSe

ssio

n

2 months gap

2 months gap

2 months gap

Experimental Tasks

Flow Chart

Control Variables

Fluid Intelligence

Age (18-30 Years)

Background Knowledge

Education Grade (partially)

Contents of Learning

Experiment Environment

EEG Recording

Sample Size 68

EGI EEG 128 Channels

Sampling rate 250

Reference Cz

Learning Contents

Human Anatomy & Physiology animated contents (2D and S3D)

Duration of Contents 10 min (presented 3 times)

3D Technology

Passive Polarized

Screen 41 inch

Distance 1.5 meter

19

?

Missing element in

the pattern

Raven’s Advance Progressive Matric Design

Eight Options to

choose the missing

part

Fluid Intelligence (RAPM )

Visual Oddball Task

Thirty percent of trials contained target stimulus and seventy percent trials

contained standard stimulus. The duration of the task was approximately 3.5

minutes.

1000ms 500ms 1000ms

ith trial structure

Standard Trial

Fixation Stimulus Inter-Trial-Interval

Target Trial

Conclusion

• The findings of this study can be concludedparticipants can recollect long-term memory fasterdue to learning in 3D display as compared to 2Ddisplay.

• Another finding is that participants exposed tolearning contents in 3D used more brain regionsduring recalling the memories as compared to thecompared to participants exposed to 2D technology.

• The reasons of this widespread involvement of thebrain network and faster recall in 3D group may bedue to:

– Depth perception (additional information)

– Storage of information in many brain regions

– High Attention (Due to stereopsis in visualization)

Conclusion …

• The analysis of event related brain potentials P3

component presented variations in parietal site Pz

related to memory performance

• High P3 amplitude at parietal site Pz was found in

high ability group, who scored higher in the

memory recall test as compared to low ability

group

• Thus, it indicated P300 positive relationship with

memory performance and general intelligence

Issues and Challenges

• Inter subjects variability

– Age, gender, regional, health and life

style

• High complexity of Brain system

• Analysis and interpretation of Brain’s

Data

• Limitations of brain imaging modalities

References

[1] T. W. K. Chang, Chen, N. S. Yu, P. T., "The effects of presentation method and information density on visual search ability and working memory load," Computers and Education, vol. 58, pp. 721-731, 2012.[2] A. D. Baddeley and G. Hitch, "Working memory," The psychology of learning and motivation, vol. 8, pp. 47-89, 1975.[3] A. D. Baddeley, R. J. Allen, and G. J. Hitch, "Binding in visual working memory: The role of the episodic buffer," Neuropsychologia, vol. 49, pp. 1393-1400, 2011.[4] M. C. Davidson, D. Amso, L. C. Anderson, and A. Diamond, "Development of cognitive control and executive functions from 4 to 13 years: Evidence from manipulations of memory, inhibition, and task switching," Neuropsychologia, vol. 44, pp. 2037-2078, 2006.[5] S. Tong and N. V. Thakor, Quantitative EEG analysis methods and clinical applications: Artech House, 2009.[6] T. a. F. Harmony, Thalıa. Silva, Juan. Bosch, Jorge. Valdés, Pedro. Fernández-Bouzas, Antonio. Galán, Lıdice. Aubert, Eduardo. Rodrıguez, Daniel, "Do specific EEG frequencies indicate different processes during mental calculation?," Neuroscience Letters, vol. 266, pp. 25-28, 1999.[7] W. Klimesch, "EEG alpha and theta oscillations reflect cognitive and memory performance: A review and analysis," Brain Research Reviews, vol. 29, pp. 169-195, 1999.[8] M. W. Grunwald, Thomas.Krause, Werner.Beyer, Lothar.Rost, Reinhard.Gutberlet, Ingmar.Gertz, Hermann-Josef, "Power of theta waves in the EEG of human subjects increases during recall of haptic information," Neuroscience Letters, vol. 260, pp. 189-192, 1999.[9] G. F. S. Wilson, Carolyne R. Ullsperger, Peter., "EEG power changes during a multiple level memory retention task," International Journal of Psychophysiology, vol. 32, pp. 107-118, 1999.[10] O. G. Jensen, J.Kounios, J.Lisman, J. E., "Oscillations in the alpha band (9-12 Hz) increase with memory load during retention in a short-term memory task," Cerebral Cortex, vol. 12, pp. 877-882, Aug 2002.