The Brain

ربّ اشرحلي صدري ويسّرلي أمري واحلل عُقدة مّن لُّلساني يفقهو قولي

الحمد لله ربّ العالَمين والعاقبة اللمتّقين والصّلوةُ والسّلام على رسولك سيّدنا محمّد

وأاله وأصحابه وأهل بيته وأهل طاعتك أجمعين - أمّا بعد

وَفِي السَّمَاءِ رِزْقُكُمْ وَمَا تُوعَدُونَ

فَوَرَبِّ السَّمَاءِ وَالأرْضِ إِنَّهُ لَحَقٌّ مِثْلَ مَا أَنَّكُمْ تَنْطِقُونَ

51.23 Then, by the Lord of heaven and earth, this is the very Truth, as much as the fact that ye can speak intelligently to each other.

Continuing from last week – This Amazing Brain is

Four pounds in weight and consists of several thousand miles of interconnected nerve cells (about 100 billion) control every movement, thought, sensation, and emotion that comprise the human experience. Within the brain and spinal cord there are ten thousand distinct varieties of neurons, trillions of supportive cells, a few more trillion synaptic connections, a hundred known chemical regulating agents, miles of minuscule blood vessels, axons ranging from a few microns to well over a foot and a half in length, and untold mysteries of how—almost flawlessly—all these components work together. This is the amazing brain.

Last week we explained to you the The regions of the Cerebral Cortex – where we referred to: - the visual, auditory, olfactory, Somatosensory, and Motor) are called Primary, since they are the ones most directly concerned with the input and output of the Brain.

Near to these Primary regions are the Secondary regions of the Cerebral Cortex, which are concerned with a more subtle and complex level of abstraction -

the sensory information received by the visual, auditory and Somatosensory Cortexes is processed at the associated

Secondary regions, and the Secondary Motor region is concerned with conceived plans of motion which get translated into more specific directions for actual muscle movement by the Primary Motor Cortex.

(Let us leave aside the olfactory Cortex in our considerations, since it behaves differently, the exception - remember? - and rather little seems to be known about - say the researchers).

The remaining regions of the Cerebral Cortex are referred to as tertiary - or the Association Cortex. (see figure)

Functional Divisions of the Cerebral Cortex

The cerebral cortex is responsible for many "higher-order" functions like language and information processing. Language centers are usually found only in the left cerebral Hemisphere.

Remember the patient who had a Cerebral Tumour involving the Left Parietal Lobe with advanced destruction of the Superior Parietal Lobule. – this is the Somatosensory Area - usually referred to as Somaesthetic Association Area - where the sensations of touch, pressure and Proprioception are integrated: (Proprioception - means: pertaining

to, or made active by - stimuli arising from movement in the tissues. i also told you that when a hair brush is placed in his hands with his eyes closed he could not identify the 3 dimensional object. He will not be able to recognize even a key or any object placed in his hands. The worst thing that could happen is - that the destruction of the Posterior part of the Parietal Lobe - which integrates Somatic (the body sensations) and visual sensations will interfere with the "appreciation" of body image on the opposite side of the body. That is the individual may fail to recognize the opposite side of the body as his own. He fails to wash it or dress it or to shave that side of his face. (SubhanAllah) it is largely in these tertiary regions that the most abstract and sophisticated activity of the Brain is carried out.

It is here - to some extent - in conjunction with the periphery - that the information from various different sensory regions is intertwined and analyzed in a very complex way, memories are laid down, pictures of the outside world are constructed, general plans are conceived and evaluated, and speech is understood or formulated.

وَهُوَ الَّذِي أَنْشَأَ لَكُمُ السَّمْعَ وَالأبْصَارَ وَالأفْئِدَةَ قَلِيلا مَا تَشْكُرُونَ

23.78 It is He Who has created for you (the faculties of) hearing, sight, feeling and understanding: little thanks it is ye give!

ثُمَّ سَوَّاهُ وَنَفَخَ فِيهِ مِنْ رُوحِهِ وَجَعَلَ لَكُمُ السَّمْعَ وَالأبْصَارَ وَالأفْئِدَةَ قَلِيلا مَا تَشْكُرُونَ

32.9 But He fashioned him in due proportion, and breathed into him something of His spirit. And He gave you (the faculties of) hearing and sight and feeling (and understanding): little thanks do ye give!

قُلْ هُوَ الَّذِي أَنْشَأَكُمْ وَجَعَلَ لَكُمُ السَّمْعَ وَالأبْصَارَ وَالأفْئِدَةَ قَلِيلا مَا تَشْكُرُونَ

67.23 Say: "It is He Who has created you (and made you grow), and made for you the faculties of hearing, seeing, feeling and understanding: little thanks it is ye give.

Speech is particularly interesting, because it is normally thought of as something very specific to human intelligence. It is curious that - in the vast majority of right -handed people and in most Left-handed people - the speech centres are mainly just on the Left-hand side of the Brain.

The essential Areas are "Broca's Area" - a region in the lower rear part of the Frontal Lobe, and another called "Wernicke's Area, in and around the upper rear part of the temporal Lobe (see fig.)

Broca's Area is concerned with the formulation of sentences, and Wernicke's Area with the comprehension of language.

Damage to Broca's Area impairs speech but leaves comprehension intact, that is, destructive Lesions of the Motor speech Area of Broca (Left Inferior Frontal Gyrus) result in the loss of ability to produce speech, that is termed - "Expressive Aphasia".

The patients however, retain the ability to think the words they wish to say. They can write the words, and they can understand their meaning when they see or hear them.

Whereas with damage to Wernicke's Area, speech is fluent but with little content. Actually what happens is -

That destructive Lesions in the Wernicke's speech Area in the dominant Hemisphere produce a loss of ability to understand the spoken and written word - this is termed "Receptive Aphasia".

Since Broca's Area is unaffected, speech is unimpaired, and the patient can produce fluent speech. However he/she is unaware of the meaning of the words he/she uses and they use incorrect words or even nonexistent words. The patient is also unaware of his

Lesions - rather destructive Lesions involving both Broca's and Wernicke's speech Areas result in loss of the production of speech and the understanding of the spoken and written word - this is termed : Global Aphasia.

Destructive Lesions in the Angular Gyrus in the Posterior Parietal Lobe (part of Wernicke's Area) divides the pathway between the visual Association Area and the Anterior part of Wernicke's Area. This results in the patient being unable to read - Alexia or Unable to write - Agraphia.

A nerve bundle called the "Arcuate Fasciculus" (arched bundle of roots, nerves etc.) connects the two Areas.

When this is damaged, comprehension is not impaired and speech remains fluent; but comprehension cannot be vocalized.

We can now form a crude picture (a very basic understanding) of what the Cerebrum does. see fig.

Cortical Area	Function	Broca's Area Wernicke's Area Images courtesy of Slice of Life.
Prefrontal Cortex	Problem Solving, Emotion, Complex Thought
Motor Association Cortex	Coordination of complex movement
Primary Motor Cortex	Initiation of voluntary movement
Primary Somatosensory Cortex	Receives tactile information from the body
Sensory Association Area	Processing of multisensory information
Visual Association Area	Complex processing of visual information
Visual Cortex	Detection of simple visual stimuli
Wernicke's Area	Language comprehension
Auditory Association Area	Complex processing of auditory information
Auditory Cortex	Detection of sound quality (loudness, tone)
Speech Center (Broca's Area)	Speech production and articulation

Pre-Frontal Cortex – Ideas, Judgments, Feelings, Social Behaviour will be affected.

Secondary Visual Cortex – Loss of Ability to recognize objects in the opposite Field Vision.

Primary Auditory - Slight Bi-Lateral Loss of Hearing – But Loss will be greater in opposite ear.

Main Defect being the inability to locate the source of sound – Bi-Lateral destruction will result in complete deafness.

Secondary Auditory – Inability to interpret sounds -= May experience word deafness – “Acoustic Verbal Agnosia”

Primary Somasthetic Area – The inability to recognize – Heat – Degrees of Warmth.

The Brain's "input" comes from auditory, visual, tactile and other signals which first register in the Cerebrum at the "Primary" portions of mainly the rear Lobes-Parietal, temporal and occipital).

The Brain's "output" in the form of activating movements of the body is mainly achieved by Primary portions of the Frontal Lobes of the Cerebrum. in between, some kind of processing takes place. In a general way there is movement of the Brain's activities starting at the Primary portions of the rear Lobes, moving onto the Secondary portions, as the input data are analyzed, and then on to the tertiary portions of the rear Lobes as these data become fully comprehended - e.g. as with the comprehension of speech at Wernicke's Area - the Arcuate Fasciculus - the bundle of nerve fibres referred to above, but not on both sides of the Brain –

Wernicke's Area is connected to Broca’s Area by a bundle of Nerve Fibres called Arcuate Fasciculus. It received fibres from the Visual Cortex in the Occipital Lobe and the Auditory Cortex in the Superior Temporal Gyrus.

Wernicke's Area permits the understanding of the written and spoken Language and enables a person to read and understand it - then carries this processed information to the Frontal Lobe, where general plans of action are formulated in its tertiary regions - e.g. as with the formulation of speech in Broca's Area –

In other words, Broca’s Speech Area brings about the formation of the words with the adjacent Primary Motor Areas of Muscles of Larynx, Mouth, Tongue, Soft Palette and the Respiratory Muscles are appropriately stimulated and “Say it out Loud”.

These general plans of action are translated into more specific conceptions about movements of the body in the Secondary Motor regions and finally the Brains activity moves on to the Primary Motor Cortex where signals are sent on, ultimately, to various groups of muscles in the body (and often to several at once).

The picture of a superb computing device seems to be presented to us. Please note that Allah Azzawajall's creation of the Brain and absolute activity of the Central Nervous System is far more complicated than the scientists have found out by trial and error.

We must not jump in too fast with our ready explanations. The general picture of the Cerebrum's activity as presented above, in only a very rough one. in the first place, even the reception of vision is not as clear-cut as we have presented it. There appear to be several different - though more minor - regions of the Cortex where maps of the visual field are made, apparently with various other purposes. and our awareness of vision seems to differ with respect to them-

There are also seem to be other subsidiary sensory and Motor regions scattered about the Cerebral Cortex -

For example, the movements of the eye can be activated by various points in the rear Lobes.

Before I go on to the other parts of the Brain, I would like to just mention something of Cerebral dominance :

Although both Hemispheres are almost identical in structure, we know that in the majority of the adult population - handedness (right or Left), perception of language, speech, spatial judgment, and Areas of behaviour are controlled by one Hemisphere and not the other.

About 90 percent of the people are right-handed, and the control resides in the Left Hemisphere.

In 90 percent of the individuals, speech and understanding of spoken and written language are controlled by the Left Hemisphere. - hence, in most adults, the Left Cerebral Hemisphere is dominant.

From a clinical point of view- The age at which Cerebral dominance comes into effect is important for example – when Cerebral damage occurs before the child has learned to speak, speech usually develops and is maintained in the remaining intact Hemisphere (the

undamaged Hemisphere) this transference of speech control is much more difficult in older persons.

*. Apparently it is responsible for precise co-ordination and control of the body.

When one is learning a new skill, be it walking or driving a car - one must think through each action in detail...

But once the skill has been mastered and has become "second nature" - as we usually put it - the Cerebellum takes over.

You will also note that it is a very familiar experience that if one "thinks" about one's actions that has been so mastered, then that person's easy control may be temporarily lost.

"thinking" about seems to involve the re-introduction of Cerebral control. Although a consequent flexibility of activity is thereby introduced, the flowing and precise Cerebellar action is lost.

** Another important thing that you should know is - that in the case of the Cerebrum you learnt that there is a crossing - over behaviour;

The right side of the Cerebrum controls the Left side and vice versa. But in the case of Cerebellum - curiously - there is no "crossing-over" behaviour - the Right Half of the Cerebellum largely controls the Right Side of the body and the Left half the Left side of the body. Damage or Lesions to the Cerebellum or normally called Cerebellar Dysfunction and produce the following signs and symptoms:

1. The muscles lose resilience - elasticity/recoil - to palpation - lose the elasticity or the recoil effect to touch. This condition is called hypotonia.

The head is often rotated and flexed and the shoulder on the side of the Lesion is lower than on the normal side.

The patient assumes a wide base when he stands and is often stiff-legged to compensate for loss of muscle tone.

3. Disturbance of voluntary movement - this is called Ataxia: inability to co-ordinate voluntary movements.

In this instance the muscles contract irregularly and weakly. (normally there is a rhythm in muscular contraction)

Tremors occur when fine movements such as buttoning clothes, writing and shaving are attempted......

muscle groups fail to work harmoniously and there is a "decomposition of movement"

when the patient is asked to touch the tip of his nose with his index finger the movements are not properly co-ordinated and the finger either passes the nose (past-pointing) or hits the nose.

A similar test can be performed on the lower limbs by asking patient to place the heel of one foot on the shin of the opposite leg.

If you ask the patient to pronate and supinate - take palm downward or backward and palm upward or forward (this action is caused by the muscle of the fore-arm)-

On the side of the Cerebellar Lesion the movements are slow, jerky and incomplete.

5. movement produced by tendon reflexes tends to continue for a longer period of time than normal e.g. the pendular knee jerk, for example, occurs following tapping the patellar tendon - the leg moves like a pendulum.

6. Ataxia of the Ocular Muscles: i.e. inability to co-ordinate voluntary movements of the eye muscles. There is a rhythmical oscillation of the eyes. You will see the eyes are deviated in a horizontal direction. This is referred to as Nystagmus - in medical parlance.

here articulation is jerky and the syllables are often separated from one another. Speech tends to be explosive and the syllables often are slurred.

One thing that you should note is that in Cerebellar injury, there is no paralysis and there are no sensory changes.

Although muscle Hypotonia - defective muscle tone - and inco-ordination may be present, the disorder is not limited to specific muscles or muscle groups....... but rather an entire extremity or the entire half of the body is involved.

And if both the Cerebellar Hemispheres are involved, then the entire body may show disturbances of muscle action - even though there is no wasting away of the muscle (atrophy). this is called Dysarthria.

Since this is unpaired and influences midline structures, muscle in-coordination involves the head and trunk and not the limbs.... there is a tendency to fall forward or backward.

There is difficulty in holding the head steady and in an upright position. There also may be difficulty in holding the trunk erect. This is called the Medullablastoma of the Vermis - in children.

[Syndrome refers to a group of symptoms and/or signs which occurring together, produce a pattern or symptom complex – typical of a particular disease.]

A Tumour of one Cerebellar Hemisphere may be the cause of this Syndrome. here the movements of the limbs,

Especially, the arms are disturbed. - swaying and falling to the side of the Lesion.

** acute Lesions produce sudden severe symptoms and signs; but there is considerable clinical evidence to show that patients can recover completely from large Cerebellar injuries.

meaning that by the Mercy of Allah Azzawajall the other Areas of the Central Nervous System can compensate for loss of Cerebellar function.

1. A 37 year-old man visited his physician because he had noticed clumsiness of his right arm. when he tried to insert a key in a lock, or tried to write, his right hand had a tremor.

When he walks- he felt a tendency to reel over to the right, as he had been drunk. His face was tilted slightly to the Left. And the right shoulder was held lower than the Left.

passive movements of the arms and legs revealed that he had a defective muscle tone (hypotonia) and looseness on the right side.

When he was asked to walk heel-toe along a straight line on the floor, he swayed over to the right side.

when he was asked to touch his nose with his right index finger, the right hand displayed tremor and the finger tended to overshoot the target.

Diagnosis : he was found to be suffering from a Tumour of the right Cerebellar Hemisphere.

Because the clumsiness, tremor, muscle incoordination, hypotonia occurred on the right side of the body - it is clear that the Lesion or injury had been on the right Cerebellar Hemisphere. All the other symptoms - proved beyond any doubt that more and more of the Cerebellum was becoming destroyed as the Tumour rapidly expanded.

A person was walking – with his right arm hanging down by his side and only the Left was swinging.

A normal person when he/she is walking, normally the arms at both sides. The side of the arm - right side in this instance, shows that there is a unilateral Lesion involving the right Cerebellar Hemisphere - this demonstrates the absence of coordination between different groups of muscles on the same side of the body.

This is the case of a 4 1/2 year old boy. This boy when he wakes in the morning he has attacks of vomiting and a tendency to be unsteady on standing up. The child walks with an unsteady gait and often fell backward. He tends to stand with his legs well apart. The head was larger for his age and the suture lines of the skull could be easily felt. A retinal examination with an ophthalmoscope showed pathological accumulation of fluid in tissue

All the symptoms was due to a Tumour where both Cerebellar Hemispheres were involved.

There had been internal hydrocephalus - water in the Brain - that accumulates because the cerebrospinal fluid is unable to escape through the foramina (an aperture) in the roof of the fourth ventricle). This had resulted in the rapid rise in the intra-cranial pressure owing to rapid increase in size of the Tumour.

The best part was that they had observed evidence of internal hydrocephalus only when they performed the autopsy.

And again there they saw that the Tumour had invaded the fourth ventricle extensively.

Just Look at How Allah in His Mercy has kept you – free of illnesses and diseases:

إِنَّ اللَّهَ لَذُو فَضْلٍ عَلَى النَّاسِ وَلَكِنَّ أَكْثَرَ النَّاسِ لا يَشْكُرُونَ

2.243 . . For Allah is full of bounty to mankind, but Most of them are ungrateful.

وَإِذْ تَأَذَّنَ رَبُّكُمْ لَئِنْ شَكَرْتُمْ لأزِيدَنَّكُمْ وَلَئِنْ كَفَرْتُمْ إِنَّ عَذَابِي لَشَدِيدٌ

14.7 And remember! your Lord caused to be declared (publicly): "If ye are grateful, I will add more (favours) unto you; But if ye show ingratitude, truly My punishment is terrible indeed."

يَعْرِفُونَ نِعْمَةَ اللَّهِ ثُمَّ يُنْكِرُونَهَا وَأَكْثَرُهُمُ الْكَافِرُونَ

16.83 They recognise the favours of Allah; then they deny them; and most of them are (creatures) ungrateful.

وَفَعَلْتَ فَعْلَتَكَ الَّتِي فَعَلْتَ وَأَنْتَ مِنَ الْكَافِرِينَ

26.19. "and you did a deed of yours which (you know) you did and you are an ungrateful (wretch)!"

وَإِنَّ رَبَّكَ لَذُو فَضْلٍ عَلَى النَّاسِ وَلَكِنَّ أَكْثَرَهُمْ لا يَشْكُرُونَ

27.73 But verily thy Lord is full of grace to mankind: Yet most of them are ungrateful.

67.23 Say: "It is He Who has created you (and made you grow), and made for you the faculties of hearing, seeing, feeling and understanding: little thanks it is ye give.

وَلَقَدْ مَكَّنَّاكُمْ فِي الأرْضِ وَجَعَلْنَا لَكُمْ فِيهَا مَعَايِشَ قَلِيلا مَا تَشْكُرُونَ

7.10 It is We Who have placed you with authority on earth, and provided you therein with means for the fulfilment of your life: small are the thanks that ye give!

وَاللَّهُ أَخْرَجَكُمْ مِنْ بُطُونِ أُمَّهَاتِكُمْ لا تَعْلَمُونَ شَيْئًا وَجَعَلَ لَكُمُ السَّمْعَ وَالأبْصَارَ وَالأفْئِدَةَ لَعَلَّكُمْ تَشْكُرُونَ

16.78 It is He Who brought you forth from the wombs of your mothers when ye knew nothing; and He gave you hearing and sight and intelligence and affections: that ye may give thanks (to Allah).

بَلْ نَقْذِفُ بِالْحَقِّ عَلَى الْبَاطِلِ فَيَدْمَغُهُ فَإِذَا هُوَ زَاهِقٌ وَلَكُمُ الْوَيْلُ مِمَّا تَصِفُونَ

21.18 Nay, We hurl the Truth against falsehood, and it knocks out its brain, and behold, falsehood doth perish! Ah! woe be to you for the (false) things ye ascribe (to Us).

وَآتَاكُمْ مِنْ كُلِّ مَا سَأَلْتُمُوهُ وَإِنْ تَعُدُّوا نِعْمَةَ اللَّهِ لا تُحْصُوهَا إِنَّ الإنْسَانَ لَظَلُومٌ كَفَّارٌ

14.34 And He giveth you of all that ye ask for. But if ye count the favours of Allah, never will ye be able to number them. Verily, man is given up to injustice and ingratitude.

وآخِرُ دَعْوَانَا اَن ِالْحَمْدُ لِلهِ رَبِّ الْعَالَمِيْن