Higher Order Brain Functions-IV

Have you ever wondered why we have two lobes instead of one? 🧠❓🧠 Do they work as one brain or two? 🤔 Are they independent or do they communicate with each other? 🔗 Are there any hemispheric specializations ⚖️ (doesn't seem possible if you know that all neuroanatomical areas are bilaterally located, right? ↔️).

But did you know that brain areas are not exactly alike 🧠≠🧠, and that each command center deals with the opposite hemisphere 🧠↔️. All fibers cross over ↔️ except for the visual pathways, which are partially crossed 👁️🔀. This makes for a very complex research area 🔬, which was only focused in the last few decades 📅.

The earliest study reported on the "specialization" of brain hemispheric specialization was reported by a French Neurologist Marc Dax 👨‍⚕️🇫🇷. Dax presented his report on the findings of brain autopsies in a conference in 1836 📅.

The interesting findings were that patients with strokes, who had speech problems brain damage, all had damage to the left 🧠⬅️❌ (none in the right hemisphere 🧠➡️✅). Not until 25 years later did someone bring this to the attention of the world 🌍 obvious functional specialization is speech and language abilities 🗣️.

In the mid-1800s 📅, Paul Broca 👨‍⚕️ (a French neurosurgeon 🇫🇷) reported two cases of aphasia where the left hemisphere damage and speech production was identified 🧠⬅️🗣️❌. This is now known as Broca's area 🧠 (for speech articulation 🗣️).

Shortly afterwards, a German neurologist 🇩🇪, Carl Wernicke 👨‍⚕️, identified another part of the left hemisphere primarily concerned with language comprehension 👂 (Wernicke's area 🧠)

Two studies in 1959 and 1961 produced evidence that unilateral lesions produced deficits which were evidence for brain hemispheric specialization 🧠⚠️.

Roger Penfield and his colleague Ebert (1959) 👨‍🔬 reports on neurological patients 🏥 and Russel and Sapir (1961) 👨‍🔬 on military personnel 🪖. Their results indicated that language was dominant in left hemisphere 🧠⬅️🗣️ for both the left and the right hemispheric dominant persons ✅.

(Remember ⚠️: If you are right hemisphere dominant, you are left-handed 🧠➡️🤚⬅️, if you are left hemisphere dominant then you are right-handed 🧠⬅️🤚➡️)

The interest in further research in this area was stimulated accidentally 🎯. The major names in this area are Penfield 👨‍⚕️, Sperry 👨‍🔬, Gazzaniga 👨‍🔬, Milner 👩‍🔬, and many others who were pioneers in this area 🏆

In other studies, when a split-brain patient was walking through the room 🚶 he acted as a blind man not able to see while he walked 🦯❌, but he could identify objects in the areas when asked verbalize 🗣️✅.

Thus, do we have two brains or one 🧠❓🧠, this is the question researchers asked 🤔, and what is the role of each ⚖️

Famous left handers are 🤚⬅️:

• Leonardo Da Vinci 🎨
• Michelangelo 🗿
• Napoleon 👑
• Alexander the great ⚔️
• Baden Powel (ambidextrous 🤚↔️: means can use both with equal proficiency ⚖️✅)

We also have dominance for:

• Foot 🦶 (which foot used for kicking a ball ⚽ or stepping on a stair first 🪜)
• Eye 👁️ (if you are to use a telescope 🔭 which eye would you use)
• Ear 👂 (which ear do you use for listening to the telephone 📞)

Dominance can be assessing by tests such as the Harris Tests of Lateral Dominance 📋.

There are two schools of thought 💭✌️:

a) One which believes that the: brain is equipotential for specialization ⚖️ and at around 2 years of age 👶 the division of labor and specializations of the two hemispheres is completed ✅. The two hemispheres compete for control 🧠⚔️🧠 e.g., when both try to speak at the same time stuttering occurs 🗣️❌, Orton (1939) 👨‍🔬.

b) The other view point is that it is inborn and innate 🧬. This is even before any cultural or learning influences can take place 📚. For example, the planum temporal in the left hemisphere is larger in the fetus 🧠⬅️📈👶. Therefore, language is programmed to be in the left hemisphere 🗣️🧠⬅️.

At present 📅 research is ongoing 🔬 and it has been recognized that each hemisphere is specialized to work alone and to work together 🧠🤝🧠.

More interesting and intriguing is the finding that we may have our frontal cortex controlling the rest of the body and brain 🧠👑, as the Chief executive 👨‍💼.

There is now much research 🔬 which indicates that the following are located in this area 🧠:

• Judgment ⚖️
• Personality 😊
• Fore sight 🔮
• "Conscience" 😇
• Reduced impulsivity 🛑

As a child grows 👶, inhibitions of the society and culture learning are all programmed in this area 🧠📚. Similarly control of all emotions also resides here 😊😢😡🧠.

a) Luria 👨‍🔬, the father of Neuropsychology 🧠🔬 developed a series of tests to assess all abilities, but holistically 🌐 and by varying the tasks 🔄. For example, to test handed ness 🤚, he would give the same task but use different modalities 🔄 (visual 👁️, somato-sensory: touch 🤚, language command 🗣️ etc) different tests 📋). These have been incorporated in the Luria Nebraska Nueropsychological test Battery 📋🧪

b) Halstead Reitan Battery 📋 also tests such as the grooved pegboard 🔧, the tapping tests 👆 etc.

• Harris Tests of Laterality 🤚📋

Research ongoing 🔬 but both hemispheres work and compete 🧠⚔️🧠, they are working together 🤝, sharing information through corpus callosum 🔗 this gives ones behavior a holistic 🌐, and a gestalt ✨. Each hemisphere needs the other 🧠🔄🧠, to provide back up information 🔄✅.

There have been cases where through surgery 🏥 or brain injury 🤕 or even birth or developmental trauma 👶⚠️, one hemisphere has been lost 🧠❌

If there is only one hemisphere 🧠, the remaining hemisphere can take over functions- without any visible or other deficits ✅. The earlier the traumas 👶⚠️ the more easily can the functioning take place ⏰✅. In later life 👴, it becomes difficult for the hemisphere to relearn 📖❌.

Neuropsychological assessment of cognition and other functions 🧠📊 is carried out by trained neuropsychologists 👨‍🔬 (brain-behavior relationship specialists 🧠↔️🎭).

A formal interview is carried out initially 📋 followed by review of all medical and other history taking records 📄 (whether they have been treated 🏥, birth traumas 👶, school records 🏫,) interviews of parents 👨‍👩‍👧, or relatives and neuropsychological testing using formalized procedure and tests 📋🧪

Neuropsychological testing aims to assess a patient's higher order functioning 🧠⚡ of:

• Attention 🎯
• Memory 💭
• Speed of information processing ⚡🧠
• Language 🗣️
• Visual-spatial ability 👁️📐
• Sensory processing 👁️👂🤚
• Motor ability 🦵🤚
• Executive 👨‍💼 and intellectual functioning 💡

This is based on the referral questions ❓ and also the previous history of the patient 📄. This also helps in developing a rehabilitation strategy 🏥✅.

The referrals for neuropsychological assessments are 📋:

• a) Stroke patients 🧠💔
• b) Head injury patients 🤕
• c) Children with slow development 👶📉 or difficulties in speech 🗣️❌, attention 🎯❌ or learning 📖❌
• d) Chronic alcohol or substance abusers 🍺💊

There are several protocols available 📚, the two well-known batteries are:

a) The Halstead Reitan Neuropsychological Battery 📋 is older and which takes about 8 hours ⏰ for a patient to complete.

The second battery is the b) Luria- Nebraska Neuropsychological Test Battery 📋 which is developed by American Neuropsychologists 👨‍🔬🇺🇸 based on Luria's techniques. This is having a series of subtests 📊 but takes less time ⏱️ and has more flexibility 🔄 (qualitative information ✅). These tests assess:

• Motor 🦵
• Sensory 👁️👂🤚
• Visual language 👁️🗣️
• Kinesthetic 🤸
• Attention 🎯
• Memory 💭
• Receptive 👂 and expressive speech 🗣️ (speech sounds 🔊 rhythm 🥁) tests

Test also assess if the patient is following instructions through different modal tests 🔄.

Thus, the Neuropsychological tests are effective tools for a trained person 👨‍🔬✅. These tests are used for:

• Diagnosis 🏥, to identify deficits due to illness or injury 🔍
• To assess learning problems 📖❌
• Reasoning and problem-solving abilities 🧩🤔
• Ability to understand and express language 🗣️👂
• Memory and attention especially post trauma 💭🎯
• Visual-spatial memory and organization 👁️📐
• Visual-motor coordination 👁️🤚
• Higher order planning and organizing abilities 👨‍💼📋

There are excellent sites on the web 🌐 for you to visit and learn more 📚. Some of them are given in the handouts 📄, but others are as follows:

Central Nervous System Overview 🧠

Learn about an astonishingly complex system of creases 🧠, projections 📡, fibers 🔗, branching cells 🌳, colors 🎨, and connections known as the human nervous system 🧠⚡.