The Brain: what happens where?

The brain is an incredibly complex organ, capable of computing millions of impulses a second, converting these electrical currents into what we see, hear, feel at every point of our lives. And more.

Within this complexity, there is some sort of an order. 

The brain is made of two hemispheres: the left and right hemispheres. The two are connected by the corpus callosum. It has been known that cutting this bridge (ie to alleviate epileptic seizures) can split the metaphorical ‘self’: in one case, a patient whose brain had been ‘split’ would pick up a cigarette with one hand, and his other hand would knock out the cigarette in an attempt to stop himself smoking!

If you’ve ever seen a brain, the grooves are evident as is the incessant folding. There is a very deep groove found in all human brains called the Central Sulcus (sulcus being the latin name for groove/wrinkle). There is also the Lateral Sulcus, which is a groove running laterally across the brain.

Within the brain, you have the frontal lobe. This area is responsible for functions such as planning, emotions, reasoning, movement (or PERM). Within the frontal lobe, there is the motor cortex, responsible for movement.

The parietal lobe is responsible for touch, orientation and recognition. Within this lobe there is the sensory cortex, which (what a surprise) processes sensory imput.

The occipital lobe, derived from the latin occiput (genitive occipitis) “back of the skull,” from ob “against, behind” and “caput “head, is in charge of visual processing.

The temporal lobe deals with perception and recognition of auditory stimuli, memory and speech.

Now lets take a detour to inside the brain

The inside of the brain contains the Limbic system, which houses many of the structures labelled. On this diagram, you can see the Thalamus. This is a relay station, directing sensory information to the cerebral cortex for higher processing. The Hypothalamus releases hormones into the bloodstream, essential in coordinating bodily functions. The Amygdala, not shown here, is responsible for emotions. The hippocampus is involved in spatial memories, and the basal ganglia  regulates speed and smoothness of coordinated movements. The neurotransmitter dopamine is released here (of which a deficiency of results in Parkinson’s disease, why the disease is characterised by tremors and slow imprecise movement).


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