By the time your baby is born, his brain has a similar construc­tion to your own. His brain is divided into several different departments that each run a different part of the body. There are three main regions: the cerebrum, the cerebellum, and the brain stem.

The Cerebrum

The cerebrum is the largest part of his brain and accounts for around 85 per cent of brain volume and weight. The cerebrum is divided into two halves, the right and left cerebral hemispheres. These are arranged in intricate folds (gyri), small grooves (sulci) and deeper grooves (fissures) that increase the total surface area. The outer part of the hemispheres (cortex) contains brain cells arranged into six layers. In adults, the cortex measures from 2-6 mm. This is where the brain interprets all the information it receives. Beneath the cortex is a layer made up of the axons trav­elling down from their neuronal cell bodies in the cortex. When these axons eventually become myelinated, they take on a white appearance and this brain tissue will be referred to as white mat­ter. The neuronal cell bodies, which remain unmyelinated, look grey and are therefore referred to as grey matter. Embedded in the white matter are concentrations of grey neuronal cell bodies referred to as nuclei or ganglia. Large tracts of nerve axons link the different parts of each hemisphere to each other and to other regions of the brain.

The cerebral cortex is responsible for interpreting sensations, initiating movement and for the processes involved in thinking speaking writing singing calculating creating planning and organizing.

The cerebral hemispheres communicate with each other and the rest of the body through bundles of nerve fibres that cross from one side of the body to the other. The left side of the brain controls the right side of the body and vice versa. Nine out of 10 babies will show a preference for using their right hand for actions involving careful co-ordination. The remaining 10 per cent of babies are either left-handed, or able to use both the left and right hand equally well (ambidextrous). Handedness is controlled by the cerebral cortex. In most right-handed people, the left hemisphere is dominant and controls logic and speech, while the right hemisphere produces imaginative and creative thoughts. In left-handed people, this pattern of function seems to be reversed. Handedness does not seem to have any consis­tent link with intelligence, although some research suggests that left-handed people have an increased tendency to a certain amount of awkwardness when performing certain tasks.

Each lobe is divided into different regions that have their own important functions. Some regions receive information from sense organs and receptors and are involved in interpreting sen­sations such as those produced by sound and light waves. These are known as sensory areas. Other parts of the brain control the movement of voluntary muscles such as when walking or run­ning. These are known as motor areas.

Sensory Areas

Sensory parts of the cerebrum receive information from the sense organs and other receptors throughout the body. They sort and analyse information in different areas so it can be understood.

Motor Areas

Motor areas control the body’s skeletal muscles involved in vol­untary movements. The axons from cells in each motor area run together to form a motor nerve, which then crosses the body to control the opposite side. Nerve cells on the left part of the brain therefore control movement in the right-hand side of the body.

Association Areas

Association areas are where the interpretations from the sensory areas are analysed and where instructions from motor areas are fine-tuned. They are involved in thought and comprehension and make us fully conscious and aware. Association areas allow us to analyse experiences and interpret them in a logical and artistic way. In right-handed people, association areas in the left hemisphere are involved in logic and comprehension, while those on the right deal with the perception of shape and feelings.

Thalamus

The thalamus is a small cluster of grey matter deep inside each cerebral hemisphere. It acts as a relay centre that sorts, interprets and directs sensory nerve signals from the sense organs to the sensory areas of the cortex. Surrounding the thalamus is the limbic system.

The Limbic System

In evolutionary terms, the limbic system is one of the oldest parts of the brain. It influences unconscious, instinctive behaviour related to survival as well as mood and emotions. Many of these instincts become modified by learned moral, social and cultural traditions. The limbic system is closely linked to detection of smell, which is why some smells can trigger strong memories and emotions. One part of the limbic system, the hippocampus, is involved with learning, recognition of new experiences, and memory – especially of physical, three-dimensional relationships.

The Hypothalamus

The hypothalamus is situated between the thalamus and pitu­itary gland. The hypothalamus regulates body temperature, food intake, water and salt balance, blood flow, sleep-wake cycles and the secretion of some hormones. It is also responsible for gener­ating some ‘primitive’ emotions such as anger and fear.

The Cerebellum

The cerebellum is the second largest part of the brain and is found towards the rear at the base of the brain behind the brain­stem and under the occipital lobes of the cerebral hemispheres. It is divided into two, tightly folded halves that are made up of many myelinated nerve fibres. The cerebellum has a distinctive, leaf-like pattern in cross-section which is sometimes described as the tree of life. It is responsible for co-ordinating muscle movements, maintaining balance and for helping some learning processes.

The Brain Stem

The third main part of the brain, the brain stem, connects the brain to the spinal cord. It contains centres that are vital for regu­lating survival functions such as breathing heart rate, blood pres­sure, digestion, posture and reflex actions such as swallowing and vomiting. It contains the reticular activating system that helps to maintain consciousness. It also helps to control move­ments of the tongue and vocal cords involved in speech. All sen­sations from your baby’s body below his neck will have to pass through his brain stem before being relayed on their journey to higher centres in the brain.

The Meninges

The entire brain and spinal cord are protected by three mem­branes, the meninges (dura mater, arachnoid layer, pia mater) that contain blood vessels and secrete shock-absorbing cere­brospinal fluid.