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Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
The brain, learning and memory
Introduction
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Behaviour = the way organisms respon...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
The brain, learning and memory
Learned behaviour
A2 Edexcel Biology Xavier DANIEL, Ph.D.
Habituation
 Example of habituat...
The brain, learning and memory
Learned behaviour
A2 Edexcel Biology Xavier DANIEL, Ph.D.
Conditioning
 Conditioning = lea...
The brain, learning and memory
Learned behaviour
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Conditioning = learning in whic...
The brain, learning and memory
Learned behaviour
A2 Edexcel Biology Xavier DANIEL, Ph.D.
Conditioning
 Conditioning = lea...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
The brain, learning and memory
What is memory?
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Memory = ability to express or pe...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
The brain, learning and memory
The sea slug and the cellular basis of learning
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 S...
The brain, learning and memory
The sea slug and the cellular basis of learning
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 H...
The brain, learning and memory
The sea slug and the cellular basis of learning
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 W...
The brain, learning and memory
The sea slug and the cellular basis of learning
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 W...
The brain, learning and memory
The sea slug and the cellular basis of learning
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 W...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
Animals in research - an ethical conundrum
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 When experiments use animals, they ma...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
Neurotransmitters of the brain - in health and disease
Brain neurotransmitters and ill-health
A2 Edexcel Biology Xavier DA...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
Neurotransmitters of the brain - in health and disease
- Parkinson’s disease
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Par...
Neurotransmitters of the brain - in health and disease
- Parkinson’s disease
A2 Edexcel Biology Xavier DANIEL, Ph.D.
Neurotransmitters of the brain - in health and disease
- Parkinson’s disease
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Par...
Neurotransmitters of the brain - in health and disease
- Parkinson’s disease
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Par...
Neurotransmitters of the brain - in health and disease
- Parkinson’s disease
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Par...
Neurotransmitters of the brain - in health and disease
- Parkinson’s disease
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Par...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
Neurotransmitters of the brain - in health and disease
- Depression
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Diagnosis of...
Neurotransmitters of the brain - in health and disease
- Depression
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Serotonin kn...
Neurotransmitters of the brain - in health and disease
- Depression
A2 Edexcel Biology Xavier DANIEL, Ph.D.
 Treatments f...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
Neurotransmitters of the brain - in health and disease
- Development of new drugs to treat brain disease
A2 Edexcel Biolog...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
Neurotransmitters of the brain - in health and disease
- Effect of psychoactive drugs on synaptic transmission
A2 Edexcel ...
Neurotransmitters of the brain - in health and disease
- Effect of psychoactive drugs on synaptic transmission
A2 Edexcel ...
Session 5.14
Unit 5: Energy, Exercise and Coordination
Topic 8: Grey matter
5.14 The brain, learning and memory + Animals ...
Neurotransmitters of the brain - in health and disease
- MDMA – its impact on synaptic transmission
A2 Edexcel Biology Xav...
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A2 Edexcel biology session 5.14 The brain, learning and memory + animals in research an ethical conundrum + neurotransmitters of the brain - in health and disease - The brain and learning 3-3

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A2 Edexcel biology session 5.14 The brain, learning and memory + animals in research an ethical conundrum + neurotransmitters of the brain - in health and disease - The brain and learning 3-3

  1. 1. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  2. 2. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  3. 3. The brain, learning and memory Introduction A2 Edexcel Biology Xavier DANIEL, Ph.D.  Behaviour = the way organisms respond to the environment and to other members of the same species  Study of behaviour = Ethology Closely related to disciplines of ecology, genetics, physiology and psychology  Activities of animals enable them to survive, seek out favourable environments, and to reproduce  An organism receives information = sense data Continuously adjusts its responses Behaviour is based on “feedback” Behaviour uses control and co-ordination of body Using sense organs, nervous system and effectors  Behaviour is either “innate” or “learned”  Innate behaviour: instinctive, automatically triggered in certain circumstances Includes responses from reflex actions  Learned behaviour occurs when experiences are retained and used to modify behaviour on future occasions Learning - permits quick adaptations to changing circumstances - is acquired by experience - modified to anticipate future experiences  In nature, differences between innate” or “learned” behaviour not always clear cut Many animals display a range of behaviours based on both
  4. 4. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  5. 5. The brain, learning and memory Learned behaviour A2 Edexcel Biology Xavier DANIEL, Ph.D. Habituation  Example of habituation: snail touched by a leaf and retracts into its shell Soon it re-emerges - unharmed If touched again, retracts again Eventually will not respond protectively any longer A repeated stimulus that does not bring danger can safely be ignored Will save time lost for retracting Will use this time for feeding Chances of survival and reproduction increases  Habituation = a type of learning involving repeated application of a stimulus resulting in decreased responsiveness = simplest form of learned behaviour  Habituation occurs at the level of whole organisms, or individual cells e.g. snails, neurones Session 6.5 Session 5.10
  6. 6. The brain, learning and memory Learned behaviour A2 Edexcel Biology Xavier DANIEL, Ph.D. Conditioning  Conditioning = learning in which an animal forms an association between previously significant stimulus and a previously neutral stimulus or response  Two types of conditioning: 1. Classical conditioning 2. Operant conditioning
  7. 7. The brain, learning and memory Learned behaviour A2 Edexcel Biology Xavier DANIEL, Ph.D.  Conditioning = learning in which an animal forms an association between previously significant stimulus and a previously neutral stimulus or response  Two types of conditioning: 1. Classical conditioning 2. Operant conditioning  1. Classical conditioning Demonstrated by Russian experimental psychologist Ivan Pavlov (1849-1936) Working on digestion in dogs When a dog sees or smells food, it salivates = drooling
  8. 8. The brain, learning and memory Learned behaviour A2 Edexcel Biology Xavier DANIEL, Ph.D. Conditioning  Conditioning = learning in which an animal forms an association between previously significant stimulus and a previously neutral stimulus or response  Two types of conditioning: 1. Classical conditioning 2. Operant conditioning  2. Operant conditioning An association is established between a particular response and some reinforcement situation e.g. laboratory rat associates pressing a bar with delivery of food e.g. in nature a bird associates turning over a dead leaf with finding worms Reinforcement can also be negative when response to behaviour = “punishment” e.g. farm pigs associate touching electric fence with receiving slight electric shock
  9. 9. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  10. 10. The brain, learning and memory What is memory? A2 Edexcel Biology Xavier DANIEL, Ph.D.  Memory = ability to express or perform some previously learned piece of information or skill  Involves learning, storage, retention and retrieval processes Retention = continued possession, use or control of something Retrieval = obtaining stored information  Memory can be: 1. Short-term 2. Long-term  Short-term memory lasts seconds Located in frontal lobes of brain Maybe held in inter-connected neurones = circuits Exists as impulses passing around circuits Loss of short-term memory by: decay of these impulses or interference with newer circuits acquired after  Long-term memory may last forever Involves hippocampus Maybe by permanent changes in brain circuitry
  11. 11. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  12. 12. The brain, learning and memory The sea slug and the cellular basis of learning A2 Edexcel Biology Xavier DANIEL, Ph.D.  Sea slug = Aplysia californica = giant marine mollusc that feeds on large seaweeds  Grows up to 1 meter long Weighs up to 7kg  Breathes by extracting oxygen from sea water at the gills within mantel cavity Respiratory current pumped through mantel’s cavity by the action of a siphon  Body of sea slug contains around 20,000 neurones Neurones are not myelinated Nervous system much less complex than human’s  In its sea environment, sea slug constantly experiences pull and push of currents and waves + frequent contacts with sea weeds = harmless  To be effective, nervous and sensory systems have to be able to differentiate between harmless and aggressive/dangerous moves of predators  Under attack by predator Gills are withdrawn into mantle cavity = immediate, reflex action response  But habitual, harmless contacts with environment are ignored No withdrawal of gills
  13. 13. The brain, learning and memory The sea slug and the cellular basis of learning A2 Edexcel Biology Xavier DANIEL, Ph.D.  How does a violent/painful stimulation leads to withdrawal of gills into mantel? = Work of E.R. Kendel and collaborators, Nobel Prize in Medicine in 2000  Light touch stimulation of siphon leads to withdrawal of gills into mantel Habituation: extent of withdrawal lessens with repeated stimulation  Violent attack simulated by small electrical shock leads to withdrawal Even just after habituation stopped withdrawal response from happening
  14. 14. The brain, learning and memory The sea slug and the cellular basis of learning A2 Edexcel Biology Xavier DANIEL, Ph.D.  What are the basis of the habituation process in sea slug? = Work of E.R. Kendel and collaborators, Nobel Prize in Medicine in 2000 1. Chemical basis for habituation Sensory neurone from siphon= responsible for habituation Repeated stimulation to siphon triggers repeated action potentials from sensory neurone from siphon towards motor neurone towards gills muscles: muscles of gills contract Ca2+ channels of sensory neurone from siphon gradually becomes inactivated Less and less neurotransmitter (glutamate) released from sensory neurone from siphon to make gills muscles contract Less and less retraction of gills
  15. 15. The brain, learning and memory The sea slug and the cellular basis of learning A2 Edexcel Biology Xavier DANIEL, Ph.D.  What are the basis of the habituation process in sea slug? = Work of E.R. Kendel and collaborators, Nobel Prize in Medicine in 2000 2. Sensitisation When intense shock applied to tail, e.g. laboratory stimulation or predator attack Tail sensory neurone sends impulse to interneurone Interneurone sends impulse to motor neurone through neurotransmitter = serotonin Triggers enhanced uptake of Ca2+ of motor neurone More action potentials generated in motor neurone Motor neurone sends impulse to make muscles of gills contract
  16. 16. The brain, learning and memory The sea slug and the cellular basis of learning A2 Edexcel Biology Xavier DANIEL, Ph.D.  What are the basis of the habituation process in sea slug? = Work of E.R. Kendel and collaborators, Nobel Prize in Medicine in 2000 3. Short-term and long-term memory  When intense shock applied to tail in the middle of mild stimulations, Responses started to be far more vigorous Comparable to conditioning of reflexes demonstrated by Pavlov This learning only lasts briefly = short-term memory  Other programmes of conditioning resulted in long-term memory As long as three weeks  Long-term memory not based on transient metabolic changes as short-term memory But based on structural changes: number of synapses + neurotransmitter vesicles in synapses increased
  17. 17. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  18. 18. Animals in research - an ethical conundrum A2 Edexcel Biology Xavier DANIEL, Ph.D.  When experiments use animals, they may suffer physically or from “psychological stress”  Today, research using laboratory animals is extensive and intensive 3 millions animals are used every year in UK alone 20 million animals are used every year in the USA Globally, around 50 million animals are used About 90% of these animals are rodents  Idea of causing pain to an animal for experiment is unacceptable to most people Lead to introduction of laws to try and eliminate unnecessary suffering Still some people think that no animal should be used Ethics already covered in AS level Session 1.14 Session 1.17 for Mai and Jacqueline
  19. 19. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  20. 20. Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health A2 Edexcel Biology Xavier DANIEL, Ph.D.  About 100 metabolites are known to act as neurotransmitters Often difficult to establish their precise roles Because neurones are often tightly packed together, especially in the brain Plus the amount of neurotransmitters released at synapses is tiny Plus the space where they are released= synaptic cleft is tiny  But some neurotransmitters have well-established roles: 1. Acetylcholine in the PNS = Parasympathetic nervous system of the ANS = autonomous nervous system 2. Noradrenaline in the Sympathetic nervous system of the ANS 3. Glutamate in brain is excitatory In 50% of the brain synapses 4. GABA = gamma aminobutyric acid is inhibitory, only in brain One-third of the brain synapses 5. Other class of chemicals = neuropeptides = endorphines = body’s natural painkillers 6. Amines = dopamine and serotonin in brain 7. NO = gas nitric oxide all over the body Unlike other neurotransmitters, NO not synthesised in advance and stored in vesicles But formed as required, immediately active, and rapidly removed NO is potentially harmful, so it is quickly converted to nitrites and nitrates NO causes smooth muscles in blood vessels to relax: enhances blood flow by reducing blood pressure Also plays a part in erection of the penis
  21. 21. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  22. 22. Neurotransmitters of the brain - in health and disease - Parkinson’s disease A2 Edexcel Biology Xavier DANIEL, Ph.D.  Parkinson’s disease = chronic, progressive disease  Affects body movement Victims = typically aged 50-60 years Only 1-2% of humans affected Since it is not inherited, environment plays a important role  Chief symptoms: - Tremor in head, arms and hands, maximum when limbs at rest - Rigidity and stiffness of skeletal muscles - Impaired balance - Slowness of movements - Shuffling gait = way of walking makes noise when feet barely leave the ground - Stooped posture - Short steps - Difficulties in speaking - Difficulties in swallowing  Due to degeneration of particular neurones in substantia nigra They extend from substantia nigra in midbrain to basal ganglia in cerebral hemispheres They release dopamine (DA) that inhibit skeletal muscle contraction In basal ganglia, other neurones release acetylcholine (Ach) that triggers skeletal muscles contraction These neurones are not affected Level of DA decreases, but level of Ach remains the same Imbalance Dopamine / Acetylcholine Skeletal muscles contract without control
  23. 23. Neurotransmitters of the brain - in health and disease - Parkinson’s disease A2 Edexcel Biology Xavier DANIEL, Ph.D.
  24. 24. Neurotransmitters of the brain - in health and disease - Parkinson’s disease A2 Edexcel Biology Xavier DANIEL, Ph.D.  Parkinson’s disease due to imbalance Dopamine / Acetylcholine Treatment of the symptoms try to restore this balance 1. Drug selegiline Irreversible, specific inhibitor of monoamine oxidase (MAO) MAO breaks down dopamine Dopamine less broken down Level of dopamine increases Balance Dopamine / Acetylcholine restored
  25. 25. Neurotransmitters of the brain - in health and disease - Parkinson’s disease A2 Edexcel Biology Xavier DANIEL, Ph.D.  Parkinson’s disease due to imbalance Dopamine / Acetylcholine Treatment of the symptoms try to restore this balance 2. L-dopa Dopamine itself cannot croos the blood-brain barrier: useless to inject it into blood L-dopa = precursor of dopamine: is converted into dopamine L-dopa can cross the blood-brain barrier L-dopa injected, converted in brain into Dopamine Level of dopamine increases Balance Dopamine / Acetylcholine restored
  26. 26. Neurotransmitters of the brain - in health and disease - Parkinson’s disease A2 Edexcel Biology Xavier DANIEL, Ph.D.  Parkinson’s disease due to imbalance Dopamine / Acetylcholine Treatment of the symptoms try to restore this balance 3. Dopamine agonists Dopamine agonists stimulate dopamine receptors Dopamine agonists injected, post-synaptic neurone “feels” has received more dopamine Level of dopamine increases Balance Dopamine / Acetylcholine restored Dopamine receptors become les and less sensitive Symptoms become more serious over time
  27. 27. Neurotransmitters of the brain - in health and disease - Parkinson’s disease A2 Edexcel Biology Xavier DANIEL, Ph.D.  Parkinson’s disease due to imbalance Dopamine / Acetylcholine Treatment of the symptoms try to restore this balance 4. Transplanting fetal tissues rich in dopamine Successful only if fetal tissues stay in patient’s brain Fetal tissue provides dopamine Level of dopamine increases Balance Dopamine / Acetylcholine restored Fetal tissue often not stable Only a few patients experienced improvements
  28. 28. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  29. 29. Neurotransmitters of the brain - in health and disease - Depression A2 Edexcel Biology Xavier DANIEL, Ph.D.  Diagnosis of depression based on the patient’s own reported experiences + observations of their behaviour Depression is probably under-reported Especially by mid-adulthood people, when it usually starts  Chief symptoms: - Marked mood changes - Periods of profound sadness - Loss of interest and pleasure in once enjoyed activities - Feeling of worthlessness - Feeling of helplessness - Pessimism - Difficulty in concentrating - Difficulty in making decisions  In developed world 5 to 10% of people suffer from one or more episodes of depression Sometimes all their lives Many of them have a history of depression in their family Genetic basis for depression is likely
  30. 30. Neurotransmitters of the brain - in health and disease - Depression A2 Edexcel Biology Xavier DANIEL, Ph.D.  Serotonin known to affect mood Low levels of serotonin lead to depression (?) But precise relationship between serotonin and depression not known Oversimplified connection has been presented to the public?  Neurones making serotonin are in brain stem Their axons connect to areas in hind-, mid- and forebrain, including cerebral hemispheres  Treatments for depression 1. Medication 2. Psychotherapy 3. Electroconvulsive therapy
  31. 31. Neurotransmitters of the brain - in health and disease - Depression A2 Edexcel Biology Xavier DANIEL, Ph.D.  Treatments for depression 1. Medication Prescription of anti-depressant drugs e.g. Prozac = substances that inhibit re-uptake of serotonin from synaptic cleft into pre-synaptic neurone More serotonin in synaptic cleft binding to receptors on post-synaptic neurone 2 Psychotherapy Provided to individuals or groupd Only way it may work = self-cure 3. Electroconvulsive therapy = ECT = electroshock treatment Seizures are electrically induced in an anaesthetised patient Results (?)
  32. 32. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  33. 33. Neurotransmitters of the brain - in health and disease - Development of new drugs to treat brain disease A2 Edexcel Biology Xavier DANIEL, Ph.D.  Existing drugs against Alzheimer’s disease do not provide a cure They just slow down development of symptoms  Brain of Alzheimer’s patients contain too much glutamate Some existing drugs block the action of glutamate  Brain of Alzheimer’s patients are deficient in acetylcholine Some existing drugs = inhibitors of acetylcholinesterase Other existing drugs stimulate release of acetylcholine into synaptic cleft  In brain of Alzheimer’s patients, an abnormal protein accumulates = cause of the symptoms? New approach = inhibit its accumulation / break it down
  34. 34. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  35. 35. Neurotransmitters of the brain - in health and disease - Effect of psychoactive drugs on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.  Psychoactive drug = drugs that affects the mind  Have effects on synapses in the brain May alter profoundly performance of brain Because Synaptic transmission in brain linked to brain’s role in co-ordination of memory, emotions, creative and abstract reasoning powers (and co-ordination of movement through skeletal muscles) Psychoactive drugs affect behaviour, and possibly personality http://learn.genetics.utah.edu/content/addiction/mouse/  Some increase post-synaptic stimulation = agonists e.g. nicotine, heroin, morphine, cocaine, amphetamines (MDMA)  Some decrease post-synaptic stimulation = antagonists e.g. b-blockers, alcohol, opioids (= derivatives of opium), THC from Cannabis
  36. 36. Neurotransmitters of the brain - in health and disease - Effect of psychoactive drugs on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D. Agonists Antagonists
  37. 37. Session 5.14 Unit 5: Energy, Exercise and Coordination Topic 8: Grey matter 5.14 The brain, learning and memory + Animals in research - an ethical conundrum + Neurotransmitters of the brain - in health and disease - The brain and learning 3-3 The brain, learning and memory Introduction Learned behaviour What is memory? The sea slug and the cellular basis of learning Animals in research - an ethical conundrum Neurotransmitters of the brain - in health and disease Brain neurotransmitters and ill-health - Parkinson’s disease - Depression - Development of new drugs to treat brain disease - Effect of psychoactive drugs on synaptic transmission - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.
  38. 38. Neurotransmitters of the brain - in health and disease - MDMA – its impact on synaptic transmission A2 Edexcel Biology Xavier DANIEL, Ph.D.  Ecstasy = semisynthetic organic psychoactive drug Member of amphetamine group Full name = methylenedioxy-N-metamphetamine = MDMA  Immediate effects of taking MDMA: - Sense of euphoria - Sense of intimacy - Anxiety decreases - Fear decreases - Thirst - Raised heart beat - Hyperthermia (thermoregulation by brain disrupted)  Long-term effects: - Depression - Severe anxiety  MDMA acts on synapses using serotonin MDMA binds to molecules transporting serotonin Removal of serotonin impeded

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