MEMORY

1
MEMORY

• LECTURE - 13
• DR. ZAHOOR ALI SHAIKH

2
HIGHER FUNCTIONS OF BRAIN

• LEARNING
• MEMORY
• JUDGEMENT
• LANGUAGE
• SPEECH

3

• WE WILL DISCUSS MEMORY UNDER THE FOLLOWING
  HEADINGS
• WHAT IS MEMORY?
• WHERE IS MEMORY STORED?
• CLASSIFICATION OF MEMORY
• HOW STORAGE OF MEMORY OCCURS?
• MOLECULAR MECHANISM

4
Cont.

• TERMINOLOGY USED (REMEMBER THE WORDS)
• RECALL MECHANISM
• CAUSES OF LOSS OF MEMORY
• HOW TO TEST THE MEMORY

5
WHAT IS MEMORY? (LONG TERM)

• MEMORY IS STORAGE OF ACQUIRED KNOWLEDGE FOR
  LATTER RECALL
• WE KNOW LITTLE ABOUT THE MECHANISM OF MEMORY

6

• MEMORY INVOLVES
• RECEPTION OF INFORMATION
• FORMATION OF MEMORY TRACE
• CONSOLIDATION OF MEMORY TRACE
• RECALL OF MEMORY TRACE
• SEQUENCE OF EVENTS IN MEMORY
• NEWLY ACQUIERED INFORMATION SHORT TERM MEMORY
  (USUALLY LOST) OR IT IS TRANSFERRED TO LONG TERM
  MEMORY BY REHERSAL CONSOLIDATION INTO LONG TERM
  MEMORY

7

• WHERE IS MEMORY STORED?
• MEMORIES ARE STORED IN THE BRAIN AT SYNAPSES BY
  CHANGING THE BASIC SENSITIVITY OF SYNAPTIC
  TRANSMISSION BETWEEN NEURONS. WE CREATE A MEMORY
  TRACE
• MEMORY TRACE
• THE NEURAL CHANGE AT SYNAPSES WHICH IS
  RESPONSIBLE FOR RETENTION OR STORAGE OF KNOWLEDGE
  IS KNOWN AS MEMORY TRACE.
• ONCE MEMORY TRACE ARE ESTABLISHED, THEY CAN BE
  ACTIVATED BY THINKING MIND TO REPRODUCE MEMORY

8
WHAT PARTS OF BRAIN ARE RESPONSIBLE FOR MEMORY?

• MEMORY TRACES OCCUR AT MANY REGIONS OF BRAIN AT
  CORTICAL AND SUBCORTICAL REGIONS. THERE IS NO
  SINGLE MEMORY CENTER
• THE IMPORTANT MEMORY AREA ARE
• CEREBRAL CORTEX (MOTOR,SENSORY,VISUAL AUDITORY)
• PREFRONTAL CORTEX
• HIPPOCAMPUS MEDIAL TEMPORAL LOBE
• LIMBIC SYSTEM
• THALAMUS
• CEREBELLUM

9
IMPORTANT

• HIPPOCAMPUS MAINTAINS RECORD OF EVERYDAY EVENTS
  IN OUR LIFE.
• PERSON WITH HIPPOCAMPUS DAMAGE ARE EXTREMELY
  FORGETFULL TO DAILY FUNCTIONING
• HIPPOCAMPUS IS FOR SHORT TERM MEMORY
• NOTE IN ALZHEIMERS DISSEASE DAMAGE OCCURS TO
  HIPPOCAMPUS REGION THEREFORE LOSS OF SHORT TERM
  MEMORY

10

• MEMORY MAY BE
• POSITIVE
• NEGATIVE
• POSITIVEMEMORY
• IS ALSO CALLED SENSATIZATION OR FACILITATION
• IT IS DUE TO STORAGE OF MEMORY TRACES
  RECOLLECTION OF PREVIOUS THOUGHTS OR EXPERIENCES
• IT OCCURS DUE TO FACILITATION OF SYNAPTIC PATHWAYS

11

• NEGATIVE MEMORY
• IT IS ALSO CALLED HABITUATION OR INHIBITION
• IT IS CAPABILITY OF BRAIN TO IGNORE THE
  INFORMATION WHICH IS NOT IMPORTANT
• GREATER SHARE OF OUR MEMORIES ARE NEGATIVE MEMORY
• IT IS DUE TO INHIBITION OF SYNAPTIC PATHWAY

12
(FROM GUYTONS TEXTBOOK OF PHYSIOLOGY)

• CLASSIFICATION OF MEMORY
• SHORT TERM MEMORY
• MEMORY WHICH LASTS FOR SECONDS TO MINUTES
• (UNLESS THEY ARE CONVERTED INTO LONG TERM
  MEMORIES)
• Eg TO REMEMBER TELEPHONE NUMBER 7 10 DIGITS
  FOR SECONDS OR MINUTES, TILL YOU ARE THINKING
  ABOUT THE NUMBERS
• INTERMEDIATE LONG TERM MEMORY
• LASTS FOR MINUTES, HOURS, DAYS TO WEEKS, BUT THEN
  THEY WILL BE LOST ( UNLESS CONVERTED TO LONG TERM
  MEMORY)
• LONG TERM MEMORY
• WHICH ONCE STORED CAN BE RECALLED UP TO YEARS OR
  EVEN FOR WHOLE LIFE
• Eg NUMBER OF PRAYERS PER DAY
• DAYS OF THE WEEK

13
(FROM GANONGS REVIEW OF PHYSIOLOGY )

• CLASSIFICATION OF MEMORY
• SHORT TERM MEMORY
• WHICH LASTS FOR SECONDS TO HOURS HIPPOCAMPUS
• Eg MEMORY OF FEW WORDS, NUMBERS, LETTERS LIMITED
  TO 7 10 NUMBERS LIKE TELEPHONE NUMBERS, CAR
  NUMBER
• LONG TERM MEMORY
• WHICH LAST FOR DAYS, MONTHS, YEARS OR LIFETIME

14

• ANOTHER TYPE OF MEMORY
• WORKING MEMORY
• IT INCLUDES MAINLY SHORT TERM MEMORY, THAT IS
  USED DURING THE INTELLECTUAL REASONING , BUT IS
  TERMINATED AS PROBLEM IS SOLVED. PREFRONTAL
  LOBE IS INVOLVED
• Eg SEE THE TELEPHONE NUMBER , REMEMBER THE
  NUMBER WHILE PICKUP PHONE, DIAL THE NUMBER AND
  TALK ABOUT THE PROBLEM Eg Examination
  Preparation
• NOW IT IS THOUGHT THAT INTELLIGENCE DEPENDS ON
  WORKING MEMORY.

15

• MEMORY CLASSIFICATION ACCORDING TO THE TYPE OF
  INFORMATION
• DECLARATIVE MEMORY OR EXPLICIT MEMORY
• IT IS MEMORY OF SURROUNDINGS, EVENTS, TIME, Eg.
  WE PLAYED FOOTBALL GAME TODAY
• DECLARATIVE MEMORY IS DEPENDENT ON HIPPOCAMPUS

16

• MEMORY CLASSIFICATION ACCORDING TO THE TYPE OF
  INFORMATION CONT
• SKILL MEMORY OR IMPLICIT MEMORY
• IT IS LEARNING OF SKILLS Eg. LEARNING FOOTBALL,
  HOW TO HIT OR STRIKE MOVE THE BALL etc.
• SKILLS ONCE ACQIRED BECOME AUTOMATIC
• RETENTION OF SKILLS DOES NOT INVOLVE HIPPOCAMPUS
  BUT CEREBELLUM, PRIMARY MOTOR CORTEX,
  SOMATOSENSORY CORTEX, VISUAL PROCESSING AREAS

17

• HOW MEMORY IS STORED
• MEMORY DOES NOT RESIDE IN A SINGLE NEURON BUT
  CHANGES OCCUR IN THE PATTERN OF SIGNALS
  TRANSMITTED ACROSS SYNAPSES WITHIN A NORMAL
  NETWORK

18
HOW MEMORY IS STORED

• SHORT TERM MEMORY
• INVOVES TRANSIENT MODIFICATION IN THE FUNCTION OF
  SYNAPSES Eg AMOUNT OF NEUROTRANSMITTER RELEASED
  IN RESPONSE TO STIMULATION
• EXPERIMENTS ARE DONE IN SEA SNAIL (APLYSIA)
• Eg. HABITUATION OR INHIBITION SENSITIZATION
  OR FACILITATION

19
APLYSIA
20
MEMORY SYSTEM THAT HAS BEEN DISCOVERED IN THE
SNAIL APLYSIA
21
APLYSIA
22

• LONG TERM MEMORY
• INVOVES PERMENANT STRUCRURAL CHANGES BETWEEN
  EXISTING NEURONS IN THE BRAIN DUE TO ACTIVATION
  OF SPECIFIC GENES THAT CONTROL PROTEIN SYNTHESIS.
  THESE PROTEINS CAUSE
• FORMATION OF NEW SYNAPTIC CONNECTIONS
• GREATER BRANCHING ANDF ELONGATION OF DENDRITES IN
  NERVE CELL IN BRAIN AREAS INVOLVED FOR MEMORY
  STORAGE.
• INCREASE NO. OF VESICLES IN PRESYNAPTIC NEURON
• INCREASE NO. OF SIGNAL TRANSMISSION

23
LONG TERM MEMORY

• NAME OF POSITIVE REGULATORY PROTEIN FOR LONG TERM
  MEMORY IS CREB , A MOLECULAR SWITCH THAT
  ACTIVATES LONG TERM MEMORY STORAGE.

24

• CONSOLIDATION OF MEMORY (TO REMEMBER)
• FOR SHORT TERM MEMORY TO BE CONVERTED INTO LONG
  TERM MEMORY IT MUST BE CONSOLIDATED
• CONSOLIDATION OCCURS BY REPEATEDLY ACTIVATING THE
  SHORT TERM MEMORY, WHICH WILL INITIATE CHEMICAL,
  PHYSICAL AND ANATOMICAL CHANGE IN THE SYNAPSES
  THAT ARE RESPONSIBLE FOR LONG TERM MEMORY

25
CONSOLIDATION OF MEMORY (TO REMEMBER) CONT

• IT TAKES 5 TO 10 MINUTES FOR MINIMAL
  CONSOLIDATION AND ONE HOUR OR MORE FOR STRONG
  CONSOLIDATION
• SOME FACTORS PREVENT CONSOLIDATION
• HEAD INJURY BRAIN CONCUSSION
• DEEP GENERAL ANAESTHESIA SUDDENLY APPLIED
• ELECTRICALLY INDUCED BRAIN CONVULSIONS

26
(No Transcript)
27

• LOSS OF MEMORY (AMNESIA)
• RETROGRADE AMNESIA
• LOSS OF MEMORY BEFORE THE ACCIDENT
• ANTEROGRADE AMNESIA
• LOSS OF MEMORY AFTER THE ACCIDENT

28
AMNESIA
ACCIDENT
PRESENT

• PAST

RETROGRADE MEMORY BEFORE THE ACCIDENT
ANTEROGRADE MEMORY AFTER THE ACCIDENT

• HIPPOCAMPUS REMOVAL (FOR TEMPORAL LOBE EPILEPSY)
  OR LESION MAINLY ANTEROGRADE AMNESIA , LITTLE
  RETROGRADE.
• THALAMIC LESION MAINLY RETROGRADE AMNESIA
• THEREFORE IT SHOWS HIPPOCAMPUS IS RESPONSIBLE FOR
  NEW MEMORIES AND THALAMUS STORES OLD MEMORIES

29
TERMINOLOGY USED IN MEMORY

• MEMORY TRACE THE NEURAL CHANGE RESPONSIBLE FOR
  RETENTION OF KNOWLEDGE IS KNOWN AS MEMORY TRACE
• SENSITIZATION OR POSITIVE MEMORY OR FACILITATION
• NEGATIVE MEMORY OR HABITUATION OR INHIBITION
• SHORT TERM MEMORY
• LONG TERM MEMORY

30
TERMINOLOGY USED IN MEMORY CONT

• WORKING MEMORY
• MEMORY ACCORDING TO TYPE OF INFORMATION
• DECLARATIVE MEMORY
• SKILL MEMORY
• AMNESIA OR LOSS OF MEMORY
• RETROGRADE AMNESIA
• ANTEROGRADE AMNESIA

31

• RECALL OF MEMORY
• ALL COMPONENTS OF MEMORY ARE BROUGHT TO
  CONSCIOUSNESS
• RECALL OF MEMORY BY . . . .
• SIMILAR SCENE
• SIMILAR SOUND
• SIMILAR SMELL
• SIMILAR VIEW
• SIMILAR WORDS

32
DEMENTIA

• IMPAIMENT OF MEMORY, INTELLIGENCE AND PERSONALITY
  WITHOUT IMPAIRMENT OF CONSCIOUSNESS

33

• HOW TO TEST THE MEMORY?
• RECENT MEMORY TEST
• GIVE NAME AND ADDRESS TO REMEMBER (7 10 WORDS)
  THEN ASK 5 MINUTES LATER OR
• GIVE THREE ITEMS WITHIN THE ROOM AND ASK THE
  PATIENTS TO REPEAT THEIR NAMES AFTER 5 MINUTES
• DISTANT MEMORY TEST
• ASK IMPORTANT DATE WHICH PATIENT KNEW THE ANSWER
  AND CLINICIAN ALSO KNOWS THE ANSWER Eg. NATIONAL
  DAY,

34

• IMPORTANT AREAS FOR . . .
• SHORT TERM MEMORY HIPPOCAMPUS, MEDIAL TEMPORAL
  LOBE
• LONG TERM MEMORY NEOCORTEX
• DECLARATIVE OR EXPRESSIVE OR EXPLICIT MEMORY
  HIPPOCAMPUS
• SKILL OR IMPLICIT OR NON DECLARATIVE MEMORY
  CEREBELLUM, BASAL GANGLIA.
• WORKING MEMORY PREFRONTAL CORTEX
• MEMORIES VISUAL, OLFACTORY, AUDITORY ARE LOCATED
  IN RESPECTIVE CORTICAL REGIONS.

35
INTRESTING INFORMATION

• 3 SPECIES HAVE BRAIN LARGER THAN HUMANS
• ELEPHANT
• PORPOISE
• WHALE
• BUT IN RELATION TO BODY WEIGHT HUMAN BRAIN IS
  LARGE
• WEIGHT OF A HUMAN BRAIN IS ABOUT THREE POUNDS OR
  1.5 KG

36

• MEMORY
• ESSAY QUESTION EXAM RECALL MEMORY (SUBJECTS
  PRODUCE INFORMATION ON THEIR OWN)
• MCQ EXAM RECOGNITION - SUBJECTS IDENTIFY
  PREVIOUSLY LEARNED INFORMATION
• RESEARCH SHOWS RECOGNITION IS EASIER THAN RECALL

37

• ALZHEIMER DISEASE
• LOSS OF RECENT MEMORY
• AFFECTED AREAS HIPPOCAMPUS, MAMMILLARY BODY,
  ANT. HYPOTHALAMUS, PREFRONTAL CORTEX, NEOCORTEX
• THERE IS PROGRESSIVE LOSS OF SHORT TERM MEMORY AT
  THE AGE OF 50 YEARS OR AFTER
• NEUROTANSMITTER ACETYLCHOLINE IS LOST DUE TO LOSS
  OF SYNAPSES AND NEURONS CAUSED BY TOXIC PEPTIDE A
  ß1-40 AND A ß1-42
• SENILE DEMENTIA
• NOTE SENILE DEMENTIA OCCURS AFTER THE AGE OF 65
  YEARS AND IT IS SLOWLY PROGRESSIVE

38

• MEMORY
• METHOD OF STUDY IN HUMANS
• PET SCAN (POSITRIN EMISSION TOMOGRAPHY)
• MEASURES LOCAL GLUCOSE METABOLISM WHICH IS
  PROPORTIONATE TO THE NEURAL ACTIVITY
• fMRI (FUNCTIONAL MAGNETIC RESONANCE IMAGING)
• Measures local amount of oxygenated blood
  which tells about the activity of brain

39

• HOW IMPORTANT IS MEMORY . . .
• IMAGINE IF WE WERE WITHOUT MEMORY, WE WOULD NOT
  RECOGNISE ANYONE, WE WOULD REMEMBER NOTHING AND
  WOULD HAVE NO RECOLLECTION OF THE EVENTS OF OUR
  OWN LIVES. WE WOULD HAVE LACK OF KNOWLEDGE AS NEW
  BORN BABIES.

40
THANK YOU