How is the cerebral cortex organised, and how do its areas process information?
The structure and functions of the cerebral cortex, the localisation of sensory, motor and association areas, the specialisation of the two cerebral hemispheres, and the transfer of information between them by the corpus callosum.
An SQA Higher Human Biology answer on the cerebral cortex, covering the sensory, motor and association areas, the localisation of function, the specialisation of the left and right cerebral hemispheres, and the transfer of information between them by the corpus callosum.
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What this dot point is asking
The SQA wants you to describe the sensory, motor and association areas of the cerebral cortex, explain the localisation of function, describe the specialisation of the two cerebral hemispheres, and explain how the corpus callosum transfers information between them.
Localisation of function
Three kinds of area are recognised:
- Sensory areas receive and process sensory information from the receptors of the body, such as touch, temperature, sound and vision, making us aware of sensations.
- Motor areas send out motor impulses to the skeletal muscles to control voluntary movement.
- Association areas carry out the higher functions. They integrate the information arriving from the sensory and motor areas and are responsible for language, reasoning, personality, imagination and memory.
The association areas are what make the human cortex so capable, because they combine and interpret information rather than simply receiving or sending it.
The cerebral hemispheres
This crossing-over means that, for example, movement of the right hand is controlled by the motor area of the left hemisphere. The specialisation is not absolute, and the hemispheres constantly share information.
The corpus callosum
Because each hemisphere is specialised and deals with the opposite side of the body, the two halves must communicate to work as one. The corpus callosum carries impulses between them, allowing information processed on one side to be shared with the other. This is why, in everyday life, the two hemispheres act together seamlessly.
Examples in context
Example 1. A stroke affecting one side. A stroke in the left hemisphere can weaken the right side of the body and affect language, because the left hemisphere controls the right side and often handles language. This shows both localisation and the opposite-side rule in a medical context.
Example 2. Reading and language. Reading aloud involves the visual sensory areas (seeing the words), association areas (understanding and forming language) and motor areas (controlling speech muscles), with the hemispheres sharing information through the corpus callosum, illustrating how localised areas cooperate.
Try this
Q1. Name the band of fibres that connects the two cerebral hemispheres. [1 mark]
- Cue. The corpus callosum.
Q2. State which functions are carried out by the association areas of the cortex. [1 mark]
- Cue. Higher functions such as language, reasoning, personality, imagination and memory.
Exam-style practice questions
Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SQA Higher 20183 marksDescribe the functions of the sensory, motor and association areas of the cerebral cortex.Show worked answer →
A 3-mark answer needs the role of each named area.
The sensory areas receive and process sensory information from the receptors of the body, such as touch, sound and visual information, so that we become aware of sensations.
The motor areas send out motor impulses to the skeletal muscles to control voluntary movement.
The association areas carry out the higher functions: they integrate information from the sensory and motor areas, and are responsible for processes such as language, reasoning, personality, memory and imagination.
Award one mark each for (1) sensory areas receive and process sensory information, (2) motor areas control voluntary movement, and (3) association areas integrate information and carry out higher functions such as language and reasoning.
SQA Higher 20213 marksExplain how the two cerebral hemispheres are specialised and how information is transferred between them.Show worked answer →
This is a 3-mark question on hemisphere specialisation.
The cerebral cortex is divided into a left and a right hemisphere, which show some specialisation of function (lateralisation). Each hemisphere also controls and receives information from the opposite side of the body, so the left hemisphere deals with the right side and vice versa.
Information is transferred between the two hemispheres by a band of nerve fibres called the corpus callosum. This allows the two hemispheres to share information and work together.
Award (1) the cortex has a left and right hemisphere with some specialisation, (2) each hemisphere deals with the opposite side of the body, and (3) the corpus callosum transfers information between the hemispheres.
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