Lesson 1: The Structure and Function of the Brain

Lobes of the Brain

Cerebral Cortex

The cerebral cortex is the thin (3-5 mm thick) convoluted (folded) outer layer of the brain.The value of the folding is that it enables a greater surface area of cerebral cortex to be contained within the skull; this gives a greater volume and enables the cerebral cortex to contain more neurons and more blood-vessels to get more oxygen and glucose (for energy) to this most fuel-hungry part of the body.

There are two main types of functional areas in the cerebral cortex:

1. the primary cortices first receive information from the environment for example: The primary visual cortex, primary auditory cortex )

2. The association areas which integrate sensory and motor information and are involved with information processing activities such as language and speech, learning, memory, thinking and problem solving

Frontal Lobe

The frontal lobes are the largest lobes and occur on the top front halves of the cerebral hemispheres. The primary motor cortex is at the back of the frontal lobes. It runs across the top of the brain from left to right.

Specific areas of the motor cortex are responsible for the movement of particular body parts.

· Right Controls Left/Left Controls Right· Top Controls Bottom/Bottom Controls Top

Motor homunculus— represents the body parts in terms of the relative size of the area each of body part occupies along the primary

motor cortex.

Association Areas in Frontal Lobe

Broca’s Area: the “Speech Production Centre” is part of the association cortex. It is located in the left frontal lobe and is involved with the production of clear, fluent speech. Broca’s area helps us with the structure of sentences and parts of speech such as adjectives, prepositions and conjunctions. Broca’s area is involved with analysing the grammatical structure of sentences that we hear as well as those that we speak.

Other association cortex in the frontal lobes is involved in• Reasoning • Planning • Thinking

Parietal Lobe

The parietal lobes are located on the top central part of the brain. Primary Areas in the Parietal Lobes – The Primary Somatosensory CortexThe primary somatosensory cortex is at the rear of the central fissure, immediately opposite the primary motor cortex.The primary somatosensory cortex registers the sense of touch, by receiving information about pressure, pain, temperature, muscle movement and position from sensory receptors around the body

It is divided by the longitudinal fissure that separates the two hemispheres.

Specific areas of the primary somatosensory cortex receive sensations from particular parts of the body.· Right Receives From Left/Left Receives From Right· Top Receives From Bottom/Bottom Receives From Top

Sensory homunculus—Similar to motor homunculus but it tells the brain how much power is needed for sensory

perception of different body parts.

Association Areas in Parietal Lobe

The association cortex of the parietal lobes is important in

Integrating visual information Monitoring the body’s position in space Determining where objects are located in space.

Temporal Lobe

Primary Area in the Temporal Lobes – The Primary Auditory Cortex

Auditory – sound – information is sent to the primary auditory cortex, located slightly above and in front of the ears.

Association Areas in Temporal Lobe

Wernicke’s area - the “Speech Reception Centre” is part of the association cortex. It is located in the left temporal lobe and is involved with the reception and comprehension of speech.

* Stores the receptor codes for language or enables comprehension of speech/language* Enables interpretation of the written word* Is used for locating words from memory to express a particular meaning* Is used for creating meaningful and/or grammatically correct speech

Other association cortex of the temporal lobes is important in

Memory - the ability to remember faces Storing of episodic memories such as our first day at school or a particular holiday

Recognition of objects

Occipital Lobe

Primary Area in the Occipital Lobes – The Primary Visual Cortex

Visual information from the eyes is sent to the Primary Visual Cortex in the occipital lobe at the back of each cerebral

hemisphere.

Association Areas in Occipital Lobe

The association cortex of the occipital lobes is important in

Selection, organisation and integration of features of visual stimuli.