The human brain.

The human brain is said to be one of the most complex objects in the universe with billions of neurons and millions of axons having a combined length of many hundred thousand miles. It has also been established that early-developmental issues of this prime organ could lead to disorders such as epilepsy and smooth brain. In a recent study, a couple of researchers from the Binghamton University in New York, tried to explore the relationship of the complex fold structure of the human brain - grooves and wrinkles - to these disorders.

Basic Structure of the Brain

* In easily comprehensible terms, the human brain is made up of two layers - the outer and the inner.

* The outer layer is called the cerebral cortex and is made up of folded grey matter that consists of small blood vessels and spherical cell bodies of neurons.

* On the other hand, the inner layer is composed of white matter which primarily consists of elongated neuron tails called myelinated axons.

Gyrification 

* The process by which the folds form on the brain is called gyrification. It starts along with the development of the foetus.

* The fold peaks are called gyrus and troughs are called sulcus.

* The abnormal development of the brain - either high or low folding rates - could lead to complex disorders like schizophrenia.

86 bn

The human brain has around 86 billion neurons and millions of axons with a total distance of many miles.

Differential Tangential Growth Hypothesis

The most accepted theory makes the assumption that the outer layer of the brain grows faster than the inner layer. This differential rate of growth puts more compressive pressure on the outer layer and forces it to fold and buckle, leading to the formation of grooves.

What Did the Researchers Do?

* Mir Jalil Razavi and Weiying used computer modelling and advanced imaging to verify the Tangential Growth Hypothesis.

* The computer model confirmed the hypothesis that the mismatch in the growth rates can cause the outer layer to buckle.

* Another study, on Nature Physics also had the same results.

How Could the Study Help?

* Better understanding of the human brain will help cure disorders like epilepsy, smooth brain etc.

* Since many of these developmental disorders start during the early years of growth, understanding the folding mechanism of the human brain will prove beneficial.

Max Surface-to-Volume Ratio

* The folding happens because it maximises the surface-to-volume ratio and relieves the compressive pressure on the outer layer.

* This allows the brain to pack in more neurons in the available space.

1500 cc

The average cranial capacity of modern humans is around 1,400 to 1,500 cc.

The Axons' Role

Axons are elongated, wire like structures that snake away from the neuron cell. The study found that if a brain area has a high density of axons then it forms a ridge (gyrus) and if there is a low density, then valleys (sulcus) are formed. This also indicates that the number of axons in the brain has a role in the origin of autism and schizophrenia.

Folding Matters

The model developed by researchers found that if the outer layer is thicker than normal, it could result in lower folds, which could cause a condition called smooth brain that could lead to stunted development and even death. On the other hand, if the outer layer is thinner, then excessive folding could lead to neurological problems such as seizures or paralysis.

Courtesy - the NIE.

My take

Quite a long way to go, to understand the functioning of the human brain! 

Tailpiece. 

Got up at a half past 6, the chores and was ready by 10.

Lekha's show all the way.