1. Unit 3 - Neurobiology and Communication CfE Higher Human Biology 17. Parts of the Brain

2. Learning Intentions I can state the function of the medulla, including breathing, heart rate, arousal and sleep I can state the function of the cerebellum, including controlling balance, posture and movement I can describe the role of the limbic system in processing information for memories and influencing emotional and motivational states I can state that the cerebral cortex receives sensory information from your surroundings I can state that the cerebral cortex is the centre for conscious thought I can state that the cerebral cortex recalls memories and alters behaviour in the light of experience I can state that the cerebral cortex co-ordinates voluntary movement I can describe what is meant by the term localisation of function I can explain localisation of function in terms of sensory, motor and association areas I can explain that some association areas deal with thought processes including language, personality, imagination and intelligence I can state that information is passed from one side of the brain to the other through a bundle of nerve fibres called the corpus callosum I can state that the left cerebral hemisphere deals with information from the right visual field and controls the right side of the body and vice versa

3. The brain is an organ composed of three interconnected layers: the central core the limbic system the cerebral cortex (outer layer of cerebrum) The Brain

4. The central core contains: The medulla – which regulates basic life processes such as breathing, heart rate, sleeping and arousal (being awake and aware of the environment) the cerebellum – which is responsible for controlling balance, posture and movement The Central Core cerebellummedulla

5. The limbic system is responsible for: processing information for long term memories regulating emotional states, e.g. fear, aggression and anxiety regulating biological motivation, e.g. hunger, thirst and sex drive. The Limbic System limbic system

6. The hypothalamus is part of the limbic system attached to pituitary gland. This acts as a link between the nervous system and the hormonal (endocrine) system. The Limbic System

7. The hypothalamus contains secretory cells that produce releaser hormones. These like any other hormone are transported to the anterior pituitary gland. These releaser hormones stimulate the release of pituitary hormones such as: Growth hormone – for growth of the body and development of long bones Thyroid stimulating hormone – needed to make thyroxin, essential for the control of metabolism Gonadotrophic hormones – first released during puberty to stimulate reproductive organs to produce and release gametes

8. Role of the Hypothalamus Contraction of Smooth Muscle Some of the axons from the neurons in the hypothalamus extend into the sympathetic and parasympathetic centres in the brains core. This allows the hypothalamus to regulate autonomic tasks such as the contraction and relaxation of smooth (involuntary muscle involved in homeostatic control e.g. vasoconstriction and contraction.

9. Control of Body Temperature The hypothalamus contains thermoreceptors which are sensitive to changes in the temperature of blood. The hypothalamus responds to this information by sending nerve impulse to effectors such as sweat glands and blood vessels.

10. Control of Water balance Osmoreceptors in the hypothalamus are sensitive to changes in the water concentration of the blood. These changes can trigger production of antidiuretic hormone (ADH) by the posterior pituitary gland. This hormone travels to the kidneys where is increases the permeability of the tubules and collecting ducts to reabsorb water when the concentration of water in the blood is low.

11. The cerebral cortex is the outer part of the cerebrum and is the centre of conscious thought and memories. The cerebrum is split into two halves called cerebral hemispheres. This is the largest and most complex part of the brain. The cerebral cortex has three key functions: receives sensory information co-ordinates voluntary movement making decisions based on experience. The Cerebral Cortex

14. The cerebrum is divided into two halves, the left and right cerebral hemispheres. The left cerebral hemisphere receives information from the right visual field and controls the right side of the body. The right cerebral hemisphere receives information from the left visual field and controls the left side of the body. The Cerebral Cortex

15. The cerebral hemispheres are not entirely separate, they are connected by a large bundle of nerve fibres known as the corpus callosum. The corpus callosum allows the transfer of information between the cerebral hemispheres and so allows the coordination of brain function, thus enabling the brain to act as an integrated whole. The Corpus Callosum

16. The cerebral cortex is highly folded (convoluted) which greatly increases its surface area, this provides greater space for more neurons allows for more interconnections between neurons The Cerebral Cortex cerebral cortex

17. Within the cerebral cortex, there are three main areas each of which deals with a particular function. the sensory areas – receives information as sensory impulses from receptors (e.g. sense organs) the association areas - analyse and interpret impulses received from the sensory areas and deals with thought processes, language, personality, imagination and intelligence. the motor areas – act on information from association areas by sending motor impulses to effectors. By this means, coordination of voluntary movement is achieved. The Cerebral Cortex – Localisation of function https://www.youtube.com/watch?v=sjbZ9QGyBi8

18. The Cerebral Cortex Frontal Lobe Temporal Lobe Medulla Oblongata Spinal cord Motor Area Sensory Area Sensory Association Area Cerebellum All these areas are duplicated in both hemispheres with the exception of the speech motor area which is found in the left hemisphere only for 90% of the population.

19. Interconnections and Communication The cerebral cortex is the centre of conscious thought. Tiny nerve fibres link up all the different areas and messages are constantly passing between them from sensory areas to motor areas via association areas. This allows the brain to make an integrated response based on all the collective information. The cerebrum is also able to recoil stored memories and then alter future decision based on the past experience. The cerebral cortex is also responsible for: Intelligence Personality Creativity Imagination conscience

20. EEG’s record the electrical activity of the cerebrum. EEG’s can indicate different levels of brain activity but are not precise enough to locate the areas of the brain which are active. Electroencephalograms – EEG’s

21. Brain scans, such as CAT, MRI or PET scans, provide a more detailed images of the brain. They can detect activity through changes in blood flow or uptake of glucose and can allow localisation of function to be identified by showing which areas are most active whilst carrying out a particular function. Brain Scans

22. PET scan of normal brain PET scan Alzheimer’s brain

23. In rare cases, a person can be born without a corpus callosum or may have it cut due to serious epilepsy, this results in split brain syndrome. The cerebral hemispheres do not share information and each processes information separately. Split Brain Syndrome

25. Questions 1.Describe the functions of the medulla and cerebellum in the central core of the brain. 2.Describe the functions of the limbic system. 3.Describe the functions of the cerebral cortex. 4.Describe the localisation of functions within the brain 5.Describe where information from one side of the brain is processed. 6.State the function of the corpus callosum

26. Answers 1. Describe the functions of the medulla and cerebellum in the central core of the brain. medulla – regulates breathing, heart rate, sleeping and arousal cerebellum –responsible for controlling balance, posture and movement 2. Describe the functions of the limbic system. Processing information for memories,regulating emotional states, e.g. fear, aggression and anxiety,regulating biological motivation, e.g. hunger, thirst and sex drive.

27. Answers (continued) 3.Describe the functions of the cerebral cortex. Receives sensory information, co-ordinates voluntary movement, making decisions based on experience 4.Describe the localisation of functions within the brain the sensory areas the association areas the motor areas

28. Answers (continued) 5.Describe where information from one side of the brain is processed. In the opposite cerebral hemisphere e.g. Information from the right side is processed in the left cerebral hemisphere 6. State the function of the corpus callosum It allows the transfer of information between the cerebral hemispheres