Cerebral Hemispheres Introduction

Introduction:

I find the brain such an amazing  and exciting part of the human anatomy! From an onlooker’s perspective, or for those who do not know anything of the human body, it might look like the consistency of one big mushroom. It is profound however that every singly part of the human brain, every aspect of the grey matter and the white matter play such a crucial part in the functioning of the human body.

Neuroscience, neuroanatomy and neuropathology seem to be an ever evolving field, as new discoveries are made, and better insights gained into the human brain. One requires an entire lifetime to study the human body in its entirety, if this be true, one requires an eternity to study the human brain.

So in the following weeks, I aim to discuss firstly the Cerebral hemispheres of the brain, followed by the functional areas of the brain and lastly discuss the cortical watershed areas. These discussions are just an introduction on the matter, and will be elaborated on in detail later.  Also if you feel you have any contribution, discussion or relevant info to add, please feel free to comment below. The brain is divided into two hemispheres (right cerebral hemisphere) and (left cerebral hemisphere). There consists 4 lobes (Frontal lobe, parietal lobe, temporal lobe and occipital lobe. The following lobes are also mentioned in medical text ( Limbic lobe, insula and lobules).

Cerebral Hemispheres and the respective lobes:

  1. žFrontal lobe – the emotional control centre of your brain where all higher executive functioning skills originate (Reasoning, problemsolving, planning, memory, motor control, initiation, judgement, social behaviour.) This is also where your personality resides.
  2. žParietal lobe – the centre for integration of sensory input relayed through the thalamus. This is also the area responsible for perception, body image and spatial relations. Damage to your left parietal lobe could be indicative of conditions such as “Gertsmann’s syndrome” – right left confusion, difficulty writing (agraphia), difficulty with mathematics (acalculia), difficulty with language (aphasia) and inability to perceive objects normally (agnosia).  Damage to your right parietal lobe could indicate the following; neglecting part of the body or space (unilateral neglect), difficulty in making things (constructional apraxia), denial of defecits (Anosagnosia), difficulty with drawing ability.
  3. žTemporal lobe – the centre mostly responsible for hearing and memory. Also plays a role in vision, emotions and speech. Damage to your left temporal lobe, could indicate difficulty understanding spoken language, remembering spoken language, recognizing words or difficulty solving mathematical problems. Damage to one’s right temporal lobe could indicate difficulty recognizing faces and or excessive talking.
  4. Occipital lobe –  responsible for the interpretation of visual input. Damage to the occipital lobe could mean that an individual will experience difficulty recognizing colours or objects, may experience visual hallucinations, have difficulty with visual processing and will likely have reading and writing impairments (alexia, agraphia).
  5. Limbic lobe –  responsible for emotional and memory storage.
  6. žInsula
  7. Lobules

Cerebral Hemispheres

Right brain versus Left brain dominance:

There has been may deliberation on brain dominance and the influence on personality and daily functioning. There is no way in ignoring the significant impact on a person who has injured either his right or his left hemisphere due to stroke or traumatic brain injury. In the individual with left sided cerebral damage, the language fallout’s, and speech difficulties are imminent. In those individuals with right sided cerebral damage, the blunted affect, poor ability to sustain attention is prominent.

What  then about brain dominance in healthy individuals? Does brain dominance and its influence on personality truly exist?

Right brain vs Left brain

Right brain functions:

  • Intuitive thought
  • Holistic perception
  • Random sequencing
  • Emotional thought
  • Non-verbal skills
  • Adventurous
  • Impulse driven
  • Creative writing/art
  • Left field vision and motor skills
  • Imagination

Left brain functions:

  • Analytical thought
  • Detail orientated perception
  • Ordered sequencing
  • Rational thought
  • Verbal Skills
  • Planning
  • Math/science
  • Right field vision and motor skills
  • Logical reasoning

Brain dominance and personality:

A recent research article titled lateral brain function, emotion and conceptualization, composed by Tucker, Don M, Psychological Bulletin, Vol 89(1), Jan 1981, 19-46 made the following observations:

Current reviews  in research on brain damage, psychiatric disorders, and normal emotion, has shown the importance of the right hemispheric function. These functions include holistic and nonverbal conceptualization to emotion. During some studies hemispheric asymmetries in psychiatric patients have suggested the importance of specific and apparently lateralized arousal systems in the brain. These lateral arousal systems are deemed important and linked to support the differential cognitive capacities of the two cerebral hemispheres.  Furthermore, the operation of these arousal systems seems to vary closely with the individual’s affective state.

Research on emotional effects of unilateral lesions has suggested that the hemispheres may be specialized not just for the kind of emotion but for its valence, positive or negative. Other research issues and methods in this area are still at an early stage of development. It does however  seem clear that further research on the lateralization of emotion should reveal how emotional processes are at one level dependent on basic neurophysiological activation processes. Also, at another level intrinsic to the differential forms of conceptualization of the two cerebral hemispheres.

Invitation to collaborate:

In the following weeks I opt to journey in detail into the above-mentioned areas and their functions.  I want to invite all neuro-scientists, neurology enthusiasts, professors, students and fans alike to comment. The idea of the discussions is to learn from each other, as Neurology is such a interesting and ever developing field. I would also greatly appreciate some comments and insights on the impact of neuro-pathology on psychiatric behavior.  All insights are welcome.

I saw this great book on Amazon, which I will definitely be using for all future Neurology reading and referencing:   Bradley’s Neurology in Clinical Practice, 2 Vol set Second edition.

This first post merely functions as an introduction ( an anatomical organogram) if we may. I have not spent time during this post to start discussing things in detail. I am excited, to start discussing various aspects of the brain and to gain insights from the greater community. All application to clinical practice is also welcome. So for those individuals working in various rehabilitation centers, please feel free to post comments on various case studies and what you have found in practice. Please keep case studies anonymous, but lets keep an open discussion going on the impact of brain injury in various parts of the brain and its impact.

Till next time…

* Reference: Neuroanatomy Second Edition  – Prof MC Bosman