3Areas of the brainThe brain is composed of Cerebral Hemispheres, Cerebellum and MedullaMedullaCerebralHemispheresCerebellum
4medullaControls autonomic activities including heart rate, and ventilation rateImpulse transmitted from medulla via sympathetic or parasympathetic branch of automatic nervous systemMedullaCerebralHemispheresCerebellum
5cerebellum Co-ordination of body movement, balance and posture CerebralHemispheresCerebellum
6cerebrum/cerebral hemispheres Highly Folded and so has a large SA.Patients with injuries to specific parts of the brain can be studied to see how their functions are altered.CerebralHemispheresCerebellumMedulla
7cerebrum/cerebral hemispheres Different parts of the brain can be stimulated electrically to see which muscles in the body respondConversely different parts of the body can be stimulated to see which parts of the brain show electrical activity.More recently MRI (magnetic resonance imaging) has been used in brain study
10The Areas can be split into 3 groups Sensory AreasMotor AreasAssociation Areas
11MotorAssociationSensorySensory area for impulses from eyes
12cerebrum/cerebral hemispheres Sensory areas of the cerebral hemispheres receive impulses from sense organs and transmit them to the association areasThe association areas of the cerebral hemispheres receive impulses - interpret them in the light of similar past experiences and transmit impulses to motor areasThe motor areas transmit impulses to the effectorsThe size of the sensory and motor areas is related to the number of receptors in that areaThe left and right cerebral hemispheres control the opposite sides of the body
13Mapping of the sensory & motor areas to the body
14Sensory & Motor MapsThe maps show that regions of the body with many sensory (or motor) neurones have corresponding large areas of the cerebrum linked to them.So for example the lips occupy a larger region of the sensory cortex than the shoulder, because there are more sensory neurones in the lips.
15Association AreasAre used to compare sensory input with previous experiences, and make decisionsThese areas are involved in speech, understanding and memory retrievalThe frontal lobes are large in humans and it is thought that they responsible for higher functions like abstract thought, personality & emotion.
16Speech The left side of the brain Patients with speech problems gave 1st clues about how the brain controls language1981 Dr Paul Broca described a patient who could only say the word “tan”.When the patient died Broca examined the brain and found damage to the left cerebral hemisphereThis part of the brain is now know as Broca’s area
18Wernicke’s AreaIn 1967 Karl Wernicke noticed damage to another region of the cortex.Werniche’s area is connected to Broca’s area by a bundle of nerve fibres.If this was damaged the patient can understand language but cannot repeat words.So Werniche’s area is concerned with understanding language. Broca’s area is concerned with controlling the muscles that produce speech
20Visual ProcessingThe visual sensory area is at the back of the brain & receives sensory input from the optic nervesThe 2 hemispheres see slightly different images from the opposite of the visual field, and differences can be used to judge distance
22Summary Sensory areas – receive input from receptors Motor areas – Origin of impulses which bring about voluntary movementsThese receive/transmit impulses from the opposite side of the bodyAssociation areas – interpret sensory information in the light of experience