1. LECTURE - 13 DR. ZAHOOR ALI SHAIKH
MEMORY
LECTURE - 13
DR. ZAHOOR ALI SHAIKH

2. HIGHER FUNCTIONS OF BRAIN:
LEARNING
MEMORY
JUDGEMENT
LANGUAGE
SPEECH

3. CLASSIFICATION OF MEMORY HOW STORAGE OF MEMORY OCCURS?
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. SEQUENCE OF EVENTS IN MEMORY
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 POSITIVEMEMORY: POSITIVE NEGATIVE
IS ALSO CALLED SENSATISATION 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
(FROM GANONGS REVIEW OF PHYSIOLOGY )

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
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

18. APLYSIA

19. MEMORY SYSTEM THAT HAS BEEN DISCOVERED IN THE SNAIL APLYSIA

20. APLYSIA

21. 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

22. LONG TERM MEMORY:
NAME OF POSITIVE REGULATORY PROTEIN FOR LONG TERM MEMORY IS “CREB” , A MOLECULAR SWITCH THAT ACTIVATES LONG TERM MEMORY STORAGE.

23. 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

24. 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. LOSS OF MEMORY (AMNESIA):
RETROGRADE AMNESIA
LOSS OF MEMORY BEFORE THE ACCIDENT
ANTEROGRADE AMNESIA
LOSS OF MEMORY AFTER THE ACCIDENT

27. 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
THALAMIC LESION MAINLY RETROGRADE AMNESIA
THEREFORE IT SHOWS HIPPOCAMPUS IS RESPONSIBLE FOR NEW MEMORIES AND THALAMUS STORES OLD MEMORIES

28. 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

29. 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

30. ALL COMPONENTS OF MEMORY ARE BROUGHT TO CONSCIOUSNESS
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

31. DEMENTIA
IMPAIMENT OF MEMORY, INTELLIGENCE AND PERSONALITY WITHOUT IMPAIRMENT OF CONSCIOUSNESS

32. HOW TO TEST THE MEMORY? RECENT MEMORY TEST: DISTANT 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,

33. 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
ALCOHOL CAUSES LOSS OF RECENT MEMORY
PATHALOGICAL CHANGES ARE SEEN IN MAMILLARY BODIES WHICH HAS EXTENSIVE CONNECTIONS TO THE HIPPOCAMPUS

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. 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 β1-40 AND A β1-42
SENILE DEMENTIA
NOTE SENILE DEMENTIA OCCURS AFTER THE AGE OF 65 YEARS AND IT IS SLOWLY PROGRESSIVE

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. METHOD OF STUDY IN HUMANS
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

38. HOW IMPORTANT IS MEMORY . . .
IMAGINE IF WE WERE WITHOUT IT 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.

39. THANK YOU