Lifebrain Monthly E-newsletter May 2020
 

Lifebrain webinar on brain health: how sleep, loneliness and depression impact the brain? 

The Lifebrain researchers will present their latest findings regarding the impact of loneliness, depression and sleep on brain health, and they will discuss the use of blood biomarkers to provide information about brain health. They will elaborate on how their findings may influence policymaking and clinical practice and may help every one of us maintain a healthy brain.

All you need to know about the human brain!

The brain is really something!
The brain is a very special organ:
 

1. The brain is protected in a “hard box” - the skull
2. The brain is surrounded by three membranes called meninges
3. The brain has a blood-brain barrier that makes it impossible for many molecules to reach the brain
4. It weighs about 1.3 kg representing about 2 % of our total body mass
5. It contains about 75-80 % water (by weight), 10 % lipids, and 10 % proteins
6. It includes about 86 x 10⁹ neurons and 85 x 10⁹ glial cells (supporter cells)
7. About 20 % of our total blood flow goes to the brain (1 L/min)
8. If the brain lacks oxygen for about 5-10 min, it will be permanently damaged
9. The energy supply of the brain is glucose - it runs on sugar!
10. The brain regulates conscious & unconscious activities

The makeup of the brain
The texture of the brain is like soft jelly, containing mostly water ~ 80 %, 10 % lipids and 10 % proteins, in addition to small amounts of minerals like calcium. The newborn brain (350 g) makes up about 10 % of total body weight, whereas the adult brain makes up ~ 2 % (1.3 kg). The brain has a very rich supply of blood vessels and uses 20 % of the total blood flow from the heart, accounting for 1 L/min. Under normal conditions, the brain exclusively uses glucose as an energy source. However, the brain can also run on something called ketone bodies mostly produced by the liver from fat during long-term fasting.

Well-protected: the surroundings of the brain
The brain is well protected inside the tough skull and three layers of membranes partly making up the blood-brain barrier, which is impermeable for many large molecules but open for essential nutrients, gases like oxygen and carbon dioxide, and lipid-soluble molecules like alcohol. Cerebrospinal fluid is generated in the brain and is found around and inside “openings” called ventricles in the brain. This special fluid acts as a “cushion” or buffer, providing mechanical and immunological support inside the skull.

Brain structure
The brain contains several areas with many neurons located together called nuclei and grey matter, whereas other areas mainly contain nerve fibers named white matter. The nerve fibers are responsible for transfer of electrical signals between nerve cells.

The surface of the mature brain is like a folded sheet of paper - it is full of “wrinkles.” The hills are called gyri and the valleys are called sulci, providing room for more cells on the given volume. Major structures of the brain include the cerebrum divided in two hemispheres, the brain stem and the cerebellum. The cerebrum is the largest and most frontal part of the brain. It is organized in several areas with major functions as pointed out in the next paragraph and in Figure 1.

Specific functions in the brain
Here you find the explanation for Figure 1. The cerebrum has several lobes (areas) with specific functions. Visual cortex (vision) is located to the occipital lobe; memory is located in especially the temporal lobe and hippocampus within this lobe. The frontal lobe is partly controlling emotional expression, problem solving, language, judgment, sexual behavior, and many motor functions. Auditory cortex (hearing) is in the temporal lobe in collaboration with parietal and frontal lobes. Cerebellum gets sensory information and coordinates motor movements and balance. The cingulate gyrus is the fiber-rich connection between the two hemisphere.

Transmission of signals in the brain
Brain activity depends on the transmission of signals between brain cells by sending electrical and chemical signals. They send electrical impulses and release chemicals called neurotransmitters in the small space between two cells. The electrical signals travel fast between nerve cells due to very well insulated nerve fibers.

No brain-no you!
Your brain makes it possible for you to sense the world like see, hear, feel, taste, and smell. In addition you can orient in space and time, think, sort information, and create new ideas. Memory is essential for many functions of the brain, making it possible to remember, and associate with other situations and happenings. You can decide to relax, execute complicated motoric movements, play music, and perform many other forms of art. The brain is not only a gigantic computer with enormous potential, it is even better than most artificial intelligence programs. Without the brain, there is no conscious life! 

Further readings

• Nordengen K, Hjernen er stjernen. Ditt eneste uerstattelige organ (in Norwegian). 2016, Kagge forlag, Oslo, ISBN13: 9788248918776
• Kahneman D. Thinking, fast and slow. 2011, Farrar, Straus and Giroux. ISBN13: 9780374275631
• Eagleman D. The Brain: The Story of You. 2016, Canongate Books Ltd, ISBN: 9781782116615

• Azevedo et al. Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled-up primate brain. Journal of Comparative Neurology. 2009, 513, 532–41
• Himwich et al. Chemical constituents of human brain. The Journal of Nervous and Mental Disease. 1955, 122, 441-7.
• Bellmund et al. Navigating cognition: Spatial codes for human thinking. Science, 2018 Nov 9;362(6415). 

Source of newsletter

This newsletter was edited by Christian A. Drevon, Professor at the Department of Nutrition, University of Oslo and Consultant in Vitas Ltd. 

CONTACT US