PYB102 – Week Two Revision
The Cerebral Cortex
The outer layer of the cortex. Cortex is Latin for ‘bark’ i.e. the outside.
Two important grooves (sulci) – the central sulcus and lateral fissure.
o Central sulcus – the boundary between the frontal lobe and parietal lobe. Seen from
the side as vertical.
o Lateral fissure – the boundary between the frontal lobe and the temporal lobe. Seen
from the side as horizontal.
Cortical Association Areas
Primary sensory areas of the cortex are those which receive initial information and then relay that
information to more specific areas of the brain nearby, called an association cortex.
Association cortex regions which are located close to the primary sensory areas only receive
information from that one sensory area. However, regions further away from primary sensory areas
receive information from multiple sensory systems and are thus able to integrate information from
Complex thought and higher order cognitive functioning
Primary Motor Cortex and Motor Association Cortex
The primary motor cortex initiates voluntary movement, while the motor association cortex
coordinates complex movement.
The primary motor cortex is actually organised in such as way that represents the body
parts’ areas on the brain. For example, one end of the cortex begins with the feet and
bottom most part of the body, ranging across the cortex until it reaches the top of the body
Primary Somatosensory Cortex and Sensory Association Area
The primary somatosensory cortex receives information from the body regarding touch,
while the sensory association area processes multisensory information.
The primary somatosensory cortex is depicted as being organised in terms of which body
parts’ function it serves, in order from the bottom of the body to the top, much like the
Larger spaces are reserved for more sensitive areas of the body.
Visual Cortex and Visual Association Area
The visual cortex detects simple visual stimuli, whiles the visual association area processes
the complex visual information.
Auditory Cortex and Auditory Association Area
The auditory cortex detects sound qualities such as pitch, tone, volume etc. while the
auditory association area is responsible for the complex processing of these raw sounds i.e.
making them into words.
Wernicke’s Area and Broca’s Area
Wernicke’s area is responsible for the comprehension of written and spoken language.
Damage to this area results in Wernicke’s aphasia or ‘word salad’ where the person can
speak, but their words often do not make any sense and are often incoherent, jumbled, or
even made up. Often, patients with this condition are not aware of their problem. Broca’s area on the other hand is responsible for the production of language. Damage to this
area can result in inability to ever speak again, or in more often cases, Broca’s aphasia.
Patients with Broca’s aphasia can comprehend language but not properly produce it. Usually
patients know that something is wrong with them.
Lateralisation of the Hemispheres
The idea that our two hemispheres are specialised in different tasks. Language, in most people, is
generally related to the left hemisphere of the brain.
The left side of our brain controls the right side of our body and vice versa.
It does not typically matter for most people that the brain works in this way, because all
information is able to be shared to both sides of the brain via the corpus callosum.
In terms of our visual field, anything to the left of our point of fixation is called the left visual
field. Similarly, anything to the right of this point is called the right visual field. The left
visual field is projected to the right side of the brain, where the right visual field is
projected to the left.
Both eyes have right AND left visual fields. Therefore, it is incorrect to say that everything
seen by the left eye is projected to the right and vice versa, because the visual fields of both
eyes are projected.
The optic chiasm is the other part of the brain which connects both hemispheres. This is
where the fields of vision from both eyes cross over, sending the information to occipital
lobe in the opposite side of the brain.
The split-brain surgery began years ago as the result of patients with severe epilepsy. The
corpus callosum was cut to prevent the epilepsy spreading across the brain and making it
Though this cured the epilepsy, it also proved to have side affects for the brain. As people
realised that this had effects on the patie