Key Area 3(c) Function of converging, diverging and reverberating pathways State what is meant by a ‘converging’ neural pathway State what is meant by a ‘diverging’ neural pathway State what is meant by a ‘reverberating’ neural pathway Identify the above pathways in a diagram State what is meant by plasticity of response State 3 occasions when plasticity of response would occur

Neural Pathways Neurones connect to each other in various ways. These combinations allow complex interaction between the neurones allowing the nervous system to carry out many complex functions.

Neural Pathways There are 3 types of neural pathway Converging neural pathways Diverging neural pathways Reverberating neural pathways

Converging Neural Pathways Converging neurones come together to meet at an intersecting point. These pathways increase the sensitivity to excitatory or inhibitory signals. Used to help us see in low light levels.

Diverging Neural Pathways Diverging neurones extend out in different directions from one starting point. Meaning diverging neural pathways can influence several neurones at the same time. Involved in fine motor control.

Reverberating Neural Pathways Reverberating neurones later in the pathway synapse with neurones earlier in the pathway sending the impulse back through the circuit. Involved in breathing. Reverberating means repeating sound/echo

Development of New Neural Pathways Neurones in the brain change during a persons lifetime depending on sensory inputs. The ability to become altered due to new environmental experiences is called plasticity of response.

Plasticity of response is created when new neural pathways are developed. These pathways can Create new responses Bypass areas of brain damage Suppress reflexes or responses to sensory impulses.

Key Area 3(d) Neurotransmitters, moods and behaviour State the role of endorphins State 4 ways endorphin levels in the body can be increased State 3 effects increased levels of endorphins can have on the body State what is meant by the reward pathway Describe dopamine’s role in the reward pathway. Name 2 neurotransmitter related disorders Describe how agonists, antagonists and other drugs (inhibitors) work when treating neurotransmitter related disorders

Neurotransmitters, Mood and Behaviour. Some neurotransmitters play a big part in how we feel and how we behave.

Neurotransmitters, Mood and Behaviour. Some neurotransmitters play a big part in how we feel and how we behave. Two examples of such neurotransmitters are Endorphins Dopamine

Endorphins Endorphins are neurotransmitters that stimulate neurons involved in reducing the intensity of pain. Increased levels are also connected with euphoric feelings, appetite modulation and release of sex hormones. Endorphin production increases in response to severe injury, prolonged and continuous exercise, stress and certain foods.

Endorphins Endorphins are neurotransmitters that stimulate neurons involved in reducing the intensity of pain. Increased levels are also connected with euphoric feelings, appetite modulation and release of sex hormones. Endorphin production increases in response to severe injury, prolonged and continuous exercise, stress and certain foods.

Endorphins Endorphins are neurotransmitters that stimulate neurons involved in reducing the intensity of pain. Increased levels are also connected with euphoric feelings, appetite modulation and release of sex hormones. Endorphin production increases in response to severe injury, prolonged and continuous exercise, stress and certain foods.

Endorphins Endorphins are neurotransmitters that stimulate neurones involved in reducing the intensity of pain. They combine with the receptors at synapses and block the transmission of pain signals. Endorphins are neurotransmitters that stimulate neurons involved in reducing the intensity of pain. Increased levels are also connected with euphoric feelings, appetite modulation and release of sex hormones. Endorphin production increases in response to severe injury, prolonged and continuous exercise, stress and certain foods.

Increased Levels of Endorphins Endorphins are produced in the hypothalamus and an increase brings about Euphoric feelings Appetite modulation (regulation) The release of sex hormones An increase in these levels can be brought about by Severe injury Prolonged/continuous exercise Stress And certain foods e.g. chocolate

Dopamine Dopamine is a neurotransmitter produced in several regions of the brain. Two of these areas are located in the limbic system. It has a key role in activating the brains ‘reward pathway’ and in the control and coordination of movement. Limbic diagram

Dopamine Dopamine is a neurotransmitter produced in several regions of the brain. Two of these areas are located in the limbic system. It has a key role in activating the brains ‘reward pathway’ and in the control and coordination of movement. Limbic diagram

Dopamine released into cerebral cortex The Reward Pathway When a survival related urge is satisfied e.g. thirst or hunger area ‘V’ releases dopamine. This travels to area ‘N’ which also produces dopamine inducing a pleasurable feeling. For this reason this route is called the reward pathway. Area N Reward pathway Area V Dopamine released into cerebral cortex Dopamine induces pleasure and reinforces particular behaviour in the reward pathway

The Reward Pathway The reward pathway involves neurones which secrete or respond to the neurotransmitter dopamine. The reward pathway is activated on engagement of beneficial behaviours e.g. eating when hungry.

Neurotransmitter related disorders Having low endorphin levels can lead to: • Feeling tearful, isolated, depressed, and hopeless • Having low self-esteem • Feeling "done to" by others • Having a low tolerance for pain (emotional and physical) • Feeling emotionally overwhelmed • Craving sweets

Alzheimer’s disease Parkinson’s disease Alzheimer’s is a form of dementia that is incurable and terminal. It is thought that this is caused by the loss of neurones which produce acetylcholine. Drugs which inhibit the enzyme which removes acetylcholine from the synaptic cleft have improved symptoms but have ultimately been ineffective. Parkinson’s is a neurological disability caused by the loss of dopamine synthesising neurones. Loss of dopamine can affect control and coordination of movement. Dopamine cannot be given as a treatment as it cannot cross the blood brain barrier. Patients are given drugs such as L-dopa (a precursor to dopamine) but they have unpleasant side effects. Research into the use of stem cells to treat PD is currently underway.

Treatment of neurotransmitter related disorders Many drugs used to treat neurotransmitter related disorders are similar to neurotransmitters. Agonists Antagonists Inhibitors Agonists bind to and stimulate receptors mimicking the neurotransmitter. Antagonists bind to specific receptors blocking the action of the neurotransmitter. e.g. Beta –blockers for anxiety Inhibitors inhibit the enzyme involved in degradation or re-uptake of the neurotransmitter. e.g. Cholinesterase inhibitors for alzheimer’s Fig 18.3 pg266 Agonist enhance activity

Key Area 3(e) Action of recreational drugs State the type of drugs that can alter a person’s neurochemistry State the 4 ways in which use of recreational drugs can alter a person’s neurochemistry. State 4 ways recreational drugs can effect neurotransmitter action State the link between recreational drugs and the reward circuit Describe what is meant by sensitisation and what it can lead to Describe what is meant by desensitisation and what it can lead to

1. What is a recreational drug? Recreational drugs are chemical substances taken for enjoyment, or leisure purposes, rather than for medical reasons. Explanation from 269

2. How do you think they work? The use of recreational drugs can affect the transmission of nerve impulses in the reward circuit of the brain.

3. What effect can they have on an individuals behaviour? This alteration in a persons neurochemistry can lead to changes in; Mood (person feels happier/more confident/ aggressive) Cognition (becomes poorer at carrying out complex mental tasks) Perception (misinterprets environmental stimuli) Behaviour (stay awake for longer/talk to themselves)

4. Can you name any DRUGS?

Recreational drugs may; 5. How would recreational drug use affect the body (think neurotransmitters!)? Recreational drugs may; Stimulate the release of neurotransmitters Imitate the action of neurotransmitters (agonists) Block the binding of neurotransmitters (antagonist) Inhibit the re-uptake or enzymatic degradation of neurotransmitters Explanation from 269

5. How would recreational drug use affect the body (think neurotransmitters!)? Explanation from 269

6. Can you think of any problems with prolonged drug use? Drug addiction can be defined as a chronic disease that causes the sufferer to seek out and use the drug, regardless of consequences.

Drug Tolerance A drug user is said to have built up a drug tolerance when their reaction to a drug has decreased and larger doses of the same drug is required to produce the same effect.

Drug Sensitisation Occurs with repeated use of a drug that acts as an antagonist (e.g. some sedatives) Blocks receptors and prevents normal neurotransmitter action NS compensates by creating more receptors and increasing their sensitivity 18.3 crop out relevant part

Drug Sensitisation This is the increase in the number and sensitivity of neurotransmitter receptors as a result of exposure to drugs that are antagonists This leads to drug addiction. 18.3 crop out relevant part

Drug Desensitisation Occurs with repeated use of a drug that acts as an agonist (e.g. cannabis) Drug use causes over stimulation of receptors NS compensates by reducing the number and sensitivity of receptors Tolerance 18.3 crop out relevant part

Drug Desensitisation This is a decrease in the number and sensitivity of neurotransmitter receptors as a result of exposure to drugs that are agonists e.g. cannabis. This leads to drug tolerance. picture

Questions from red booklet on the next slide! Key Area 3: Past Papers Paper Section Question 2016 2 10 2015 1 14, 15 9 Specimen 15 14B Exemplar 16 8,9 Yellow Booklet Questions from red booklet on the next slide!

Key Area 3: Past Papers Paper Section Question 2015 1 23, 24, 25, 26 2 10 2014 23, 24 11 2013 C (essay) 2A 2012 1B Red Booklet

Complete Q 2 from pg 276 of the textbook. Complete pg 277; what you should know.