Sunday, June 26, 2011

MEMORY- THE MOST IMPORTANT BRAIN FUNCTION

MEMORY- THE MOST IMPORTANT BRAIN FUNCTION

Introduction

Memory is, undoubtedly, the most important function of our brain. Our day-to-day functioning depends on good memory. A person with memory impairment is unable to perform even the most basic of the daily activities. This handicap is well seen in people suffering from dementia.


Better memory is also a prerequisite to being a more intelligent person, and all tests for testing I.Q (intelligence quotient) include some form of memory testing. Good memory becomes even more important in traditional teaching systems such as in India, where a student who can memorise more gets more marks, and also more accolades and so on!

Memory in other species

It is not only humans who have memory. Many lower animals too depend on various types of memory for their survival.
  • For example, migratory birds fly upto 10,000 km every year to survive harsh winters, across deserts, mountains and seas; with fear of starvation, exhaustion and death. Yet, they accurately reach the same destination without getting lost (remember, they dont have google maps, GPRS, etc). l
  • They can store upto 100,000 seeds underground and retrieve most of them later, when they need them (just imagine doing it without pen/paper or computer!) Birds store Acorn seeds (that grow into giant oak trees) in the ground, by covering with dirt. Acorn seeds are very nutritious and birds can’t eat them all for fear of becoming fat and not being able to fly
  • Remeber PAUL, THE OCTOPUS, who predicted so accurately during the recent world cup soccer!
  • Chimpanzees and gorillas have even better memory.
Some facts about human brain
Human brain is only 2% of body weight, but it receives 15% of cardiac output (blood pumped out by the heart), 20% of total body oxygen consumption and 25% of total body glucose utilization. Brain metabolism is very active, and brain continues to work even during sleep (during rapid eye movement- REM- phase of sleep, brain metabolism is 30% higher!)
At what age does learning in humans begin?
Human learning begins even before birth. All those who have read Mahabharatha know that! Abhimanyu (son of Subhadra and Arjun) learnt how to penetrate several layers of defence of Chakravyuha, while he was still in his mother's womb (while Arjuna was narrating that to Subhadra). The epic says that Subhadra fell asleep halfway, and so Arjun did not tell her the technique of coming out of Chakravyuha, and Abhimanyu could not learn that either (and later on during the war, he remembered how to enter the charavyuha, got trapped inside and got killed).

Recently, several research studies prove the above point. Ultrasound studies show that fetuses respond in a specific manner (by moving hands or legs) to a specific sound at 30 weeks of gestation. The response of fetuses were replicated at 34 weeks, indicating that they could remember the sound even after four weeks! Also, mothers know that newborn babies respond to their voice even on the first few days after birth. This is because these babies have heard their mothers' voices so many times before birth that they are very familiar with that.

One of my colleagues told me that when his wife was pregnant, world cup soccer was going on, and they would watch all the matches and discuss them in detail. This experience was handy for their yet-to-born son, who showed keen interest in soccer from very young age, and at 10, he was in the school team! So, all prospective parents, please discuss only good things because your yet to be born child is listening to every conversation!!

Brain growth is maximum during the first two years of life, and hence are very important for memory and learning. Any infection or insult to brain during this stage can adversely impact memory functions.
Between 6 months and 12 months of age, babies can recognize familiar places or people (this explains the fussiness on being brought to doctors cabin or smile on seeing grandma).

Long-term memory retention does not start until age 3, and hence most people dont have any memories of events that happened during the first three years of life.
Does memory decline with advancing age?
  •  lBrain volume is maximum at age 20 and starts to shrink after age 40!
  • lThough certain aspects of memory & cognition may change with age, most older people can function normally (indicating an insignificant memory loss)
  • lSo, memory loss causing disability in daily life of an older person is pathological,
  • lNew-learning ability and ability to form long-term memory is spared into old age. 
  • Different types of memories decline differently.
  • Episodic (what did I have for breakfast), source (where did I learn the new car) and falsh bulb (where was I on Sep 1 2001) memory decline fast
  • Semantic (words, phrases, facts) and procedural (driving a car) memory decline the least.
  • Amount of storage capacity is not an issue; however, retrieval of stored information may become slower with aging.
  • Memory lapses start in 20s, but they remain unnoticed till 50s.
  • In a recent study, psychologists asked about 2,000 participants to solve puzzles, identify patterns and remember words and details from stories, among other memory tests.
  • The top performers were 22-yr-old; researchers saw a notable decline in the ability to make rapid comparisons, remember unrelated information and detect relationships by age 27.
  • A weakening memory can usually be detected by around age 37, according to the study.
  • The good news was that people's vocabulary and general knowledge increase until at least age 60.
Memory problems in ageing- What is abnormal?


  • Forgetting things much more than you used to
  • Forgetting how to do things you've done many times before
  • Trouble learning new things
  • Repeating phrases or stories in the same conversation
  • Trouble making choices or handling money
  • Not being able to keep track of what happens each day
Whose memory is better- MEN or WOMEN?

Ever wondered why wives always manage to remember the wedding anniversary (and put you in a tight spot)! This is because verbal episodic memory (words, objects, everyday events) is better in women; however visuo-spatial memory is better in men (so women please watch, if you get stuck in dense forests of Amazon, its the men who will take you out of jungle to safety)! Women are also better at remembering faces!

"Husbands never remember marital spats, whereas wives never forget". This is because women have better emotional memory. This could also explain the higher rates of depression among women.

How to improve memory?

l1.Regular physical exercise- increases cerebral blood flow
l2. Regular brain exercises- solving puzzles, sudoku, learning a new language, or playing a new musical instrument, etc in old age can delay the onset of dementia
l3. Avoiding stress/tension; good social interaction
l
5. Good control of risk factors such as high BP, sugars or cholesterol.
6.Ensuring proper sleep and good nutrition

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Are there any memory enhancing foods?
 
l1. Grape juice- antioxidant & anti-inflammatory properties (Br J Nutrition, 2010)
l2. Strawberries, blueberries, walnuts- (J Nutrition 2009)
l3. Choline rich foods- chicken liver, eggs (J Am Coll Nutrition 2004)
l4. Chewing gum- (Appetite 2004)
l5. Apples, apricots, broccoli, cabbage, cauliflower, cherries, eggplant, fish, onions, plums, beet root, spinach, green tea, soy, olive oil,
l6. Turmeric (a compound called cucurmin) may protect against Alzheimer’s disease- this explains the lower prevalence of AD in India)!
Are there any medicines/drugs to enahnce memory?
Generally no drugs can boost memory in normal people. Memory is genetically determined and it can't be boosted. However, in people with vitamin and nutrient deficiencies, appropriate supplementation can be useful. Multivitamins are safe (containing B12, thiamine, alpha lipoic acid and folic acid). Omega 3 unsaturated fatty acids are used. Chinese herb Ginkgo biloba is also in common use. Please consult your doctor before you consume any of the medications, as even vitamins can have adverse effects!

Dr Sudhir Kumar MD (Medicine), DM (Neurology)
Consultant Neurologist
Apollo Hospitals, Hyderabad
Phone: 0091-40-23607777/60601066

1 comment:

meghana said...

sir..This has been my very favourite subject of interest. Am very much intrested a study in MIND DYNAMICS. I request you to suggest me if there are any short term courses in this particular topic.