Psychology Biological Psychology

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1 Psychology Biological Psychology 9008

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3 Summer 2001 HIGHER STILL Psychology Biological Psychology Advanced Higher Support Materials *+,-./

4 CONTENTS Introduction Statement of standards Guidelines for teachers Approaches to teaching and learning Learning environment How to use this pack Recording student attainment Student information and activities Outcomes 1 and 2 - Key Concepts and Theories Outcome 3 - Issues Psychology: Biological Psychology (AH)

5 Psychology: Biological Psychology (AH)

6 SECTION 1: GENERAL INFORMATION UNIT Biological Psychology (Advanced Higher) NUMBER D COURSE Psychology (Advanced Higher) Acceptable performance in this unit will be the satisfactory achievement of the standards set out in this part of the unit specification. All sections of the statement of standards are mandatory and cannot be altered without reference to the Scottish Qualifications Authority. OUTCOME 1 Analyse major theories in biological psychology. Performance Criteria (a) Competing theoretical explanations in biological psychology are explained accurately and comprehensively. (b) Competing theoretical explanations in biological psychology are compared accurately in terms of their main features. (c) Competing theoretical explanations in biological psychology are contrasted accurately in terms of their main features. Evidence requirements To demonstrate accurately attainment of this outcome, candidates should produce written or oral responses to cover all performance criteria. They are required to do so for two theoretical explanations chosen from the following: neural and hormonal systems and behaviour cortical functions awareness motivation emotion and stress. Written/oral responses will typically be extended responses of between 1000 and 1500 words for each theoretical explanation and associated research evidence, integrating Outcomes 1 and 2. OUTCOME 2 Evaluate research evidence relating to theories in biological psychology. Performance Criteria (a) Research evidence relating to theories in biological psychology is described accurately. (b) Research evidence relating to theories in biological psychology is explained clearly and accurately in terms of its strength and support for the theories. Psychology: Biological Psychology (AH) 1

7 (c) Validity of conclusions based on this research evidence is explained clearly and accurately. Evidence requirements To demonstrate satisfactory attainment of this outcome, candidates should produce written or oral responses to cover all performance criteria. They are required to do so for research evidence in two areas chosen from the following: neural and hormonal systems and behaviour cortical functions awareness motivation emotion and stress. Written/oral responses will typically be extended responses of between 1000 and 1500 words for each theoretical explanation and associated research evidence, integrating Outcomes 1 and 2. OUTCOME 3 Analyse an issue in biological psychology. Performance criteria (a) An issue relevant to biological psychology is explained clearly and accurately. (b) Essential arguments of this issue are explained accurately and comprehensively in a balanced way. (c) The contribution of this issue to biological psychology is explained accurately and comprehensively. Evidence requirements To demonstrate satisfactory attainment of this outcome, candidates should produce written or oral response to cover all performance criteria. They are required to do so for one issue from the following: psychology as science the use of non-human animals in research hereditary and environment biological determinism mind/brain relationships. Written/oral responses will typically be an extended response of between 1000 and 1500 words. Psychology: Biological Psychology (AH) 2

8 SECTION 2: GUIDANCE FOR TEACHERS Approaches to teaching and learning In delivering this unit, it is useful if teachers/lecturers achieve a balance between teacher/lecturer exposition and experiential learning. It is important to recognise that learners acquire and process information in a number of ways to help them learn. These include visually, orally, in discussion or exchange with others, during group-based problem solving activities, and during solitary reflection. Students should be encouraged from the beginning to draw on their own experiences, perceptions, and their previous and current learning. Personal experience of interacting with a variety of people, and in a number of different situations is an invaluable source of knowledge and is highly relevant to Biological psychology. The sharing of experiences and insights will promote general awareness that Biological psychology assists self-understanding and an understanding of humans in a variety of contexts. Students should also be encouraged to gather and use information about different people s actions, thoughts and feelings and to consider how these affect themselves and others. Relevant quality newspapers and/or magazine articles and video/film productions are useful resources, which bring Biological psychology to life so that it can be shared, by comparatively large groups of people at any one time. This remains appropriate even when the material is fictional, provided it presents us with a true picture of the human condition, which is not deliberately sensationalised. In delivering this unit it is appropriate that a multicultural approach is taken since the learning needs of individuals vary according to their cultural background. Case studies, role-play and simulations should incorporate characters and elements from different social and cultural backgrounds wherever possible. Unit induction At the beginning of the unit Biological Psychology, teachers and lecturers should ensure that Students are clear about its nature and purpose. Induction for this unit should last about two hours and should include an introduction to the content of the unit, provide a programme of work and explain the arrangements for assessment and reassessment. At this point Students can be given the Candidates Guide from the Unit Assessment Pack. This helps explain what the unit is about and how it is assessed. In order to allow Students to make a confident start, reference should be made to links with previous or other current learning with which they are familiar. It is also important to discuss and explore the nature of the course or Group Award being undertaken by the group if appropriate. It may be necessary to include induction exercises, particularly if the group is a new one. The type and number of exercises used will however depend on the nature of the particular group, their familiarity with each other and with the teacher/lecturer concerned. Psychology: Biological Psychology (AH) 3

9 Learning Environment The expertise of the teacher/lecturer is invaluable in developing skills in, approaches to, and insights about the subject of Biological psychology. Teachers/lecturers should aim to create a relaxed and enjoyable learning environment, which is both motivating and supportive. In order that a people perspective is always present the following conditions should be met: the provision of a learning climate in which students feel supported and able to express their thoughts and ideas. a teaching style that promotes a supportive learning climate. teaching and learning methods which draw on students past and present learning experience and which enable them to integrate new ideas and skills during their interactions with others. Further guidance can be found in the Psychology Subject Guide. Psychology: Biological Psychology (AH) 4

10 HOW TO USE THIS PACK Purpose of the pack This pack is designed to provide guidance and support materials to help teachers/lecturers in the delivery of the unit. The student information and activities are designed to be used by teachers/lecturers in the way that suits their preferred style of delivery and the needs of their particular student group. This pack has not been designed for open learning purposes. Additional reading, exercises, assignments etc. and answers to enclosed exercises and worksheets will be provided and facilitated by the teacher/lecturer. The student activities in the pack will require to be followed up and brought together by the teacher/lecturer in whatever way is most appropriate. The student activities in this pack cover the three outcomes and their performance criteria at Advanced Higher level. The Unit in the teaching/learning situation calls for two key concepts, their features and explanations and one issue to be covered. This Teachers Support Pack will endeavour to cover three key concepts, their features and explanations and two issues. This sequence of delivery is by no means compulsory and may be rearranged at the discretion of the teacher/lecturer responsible for delivering the unit. Using the materials The student activity and information materials in the pack include both Information and Student Activities. These support materials should be used as the focus of input by the teacher/lecturer and to develop ideas further as part of question and answer sessions and group discussions. These information sheets can be photocopied, as a separate pack should the teacher/lecturer prefer to use them either as teaching notes or as separate handout materials. Alternatively, the materials could be assembled into smaller topic packs. These general activities have been developed to include exercises for individuals, pairs, triads and small groups to conduct. Teachers/lecturers may well wish to alter the way in which these activities are carried out according to the needs of their particular group. Psychology: Biological Psychology (AH) 5

11 RECORDING STUDENT ATTAINMENT A recording proforma for teachers/lecturers to complete for individual candidate attainment is available in the Unit Assessment pack. Candidate s record of progress - for individual candidates to have a record of their attainment. Internal Assessment Record - to record their internal assessment results of the whole student group. Teachers/lecturers may devise their own alternative system for recording student attainment. GUIDANCE ON THE CONTENT AND CONTEXT FOR THIS UNIT By introducing students to a range of concepts; and associated theories, research evidence and issues in Biological psychology, it is intended to develop knowledge and understanding of Biological Psychology generally and to emphasise the significance of this area to the whole of Psychology. A choice of concepts and issues is a feature of this unit. This provides flexibility for centres to accommodate different needs and interests in studying Biological psychology at this level. Fuller information on the content of this unit is provided in the course details. GUIDANCE ON LEARNING AND TEACHING APPROACHES FOR THIS UNIT General proposals regarding approaches to learning and teaching are contained in the course details. Learning and teaching approaches should be carefully selected to support the development of knowledge and understanding, investigation and application. The learning experience at this level should be interesting, to encourage enthusiasm for the subject and to stimulate and prepare candidates for independent study. The unit should be approached using a wide range of stimulus materials and teaching approaches. Candidates should be encouraged to draw upon their own experiences and should have access to resources. The material should be up-to-date and relevant to the unit, the level of study and the interests of the candidates. The emphasis throughout should be on active learning, whether as part of a whole class, in small groups or as individuals. The outcomes are interconnected and should be approached as such. Especially so at Advanced Higher it is recommended that, wherever possible, outcomes should be covered in an integrated way. An outcome-by-outcome internal assessment approach, which could lead to a compartmentalized view of psychology, should be avoided. Psychology: Biological Psychology (AH) 6

12 GUIDANCE ON APPROACHES TO ASSESSMENT FOR THIS UNIT The National Assessment Bank will provide assessment instruments and guidance on implementation. This does not preclude teachers/lecturers from devising their own assessment tasks. Evidence of attainment of the outcomes for this unit may be provided through a variety of methods. Where an integrated approach is used for assessment, it will be necessary to identify in the candidate s response where each outcome has been met. Where assessment evidence is gathered by means of a single assessment towards the end of the unit, care should be taken to ensure that sufficient time is allowed for remediation and reassessment if required. Where a candidate has failed to achieve one or more of the outcomes, it is only necessary to reassess those outcomes that the candidate has failed to achieve. Where assessments are set which allow candidates to demonstrate performance beyond the minimum standard required, evidence gathered for internal unit assessment might also be used for grade prediction and for appeals for external course assessment. For details of the grade descriptions for external assessment, please refer to the Advanced Higher Psychology course specification. Psychology: Biological Psychology (AH) 7

13 SECTION 3: STUDENT INFORMATION AND ACTIVITIES THE STUDY OF BIOLOGICAL PSYCHOLOGY Psychology is the name given to the science which seeks to provide explanations for human behaviour and mental processes. Biological psychology, also known as biopsychology, behavioural neuroscience or behavioural biology is the scientific study of the biology of the brain and behaviour (Dewsbury 1991). The main assumption of this discipline is that biological mechanisms underlie all behaviour. Many psychology students when embarking on a course in biological psychology question the relevance of such a scientific topic. However, if we are to understand the complex interaction between brain and behaviour, mind and body it is necessary that we have a basic understanding of the cells and organs of the body and the physical and chemical changes which help determine and influence our behaviour and mental processes. Biological psychology does not provide us with all the answers regarding human behaviour but it plays an important part. Areas of research in this area include: the interaction between brain and behaviour the influence of hormones on growth and development the manner in which psychoactive substances affect cognitions and behaviour the role played by genetics and environment in influencing behaviour (traditionally known as the nature-nurture debate). Biological psychology also concerns itself with evolutionary psychology or ethology, the study of instinctive behaviours and reflexes, such as the predisposition for aggression, or nurturing. In more recent times biological psychology has also been concerned with genetic research - looking for a genetic basis for certain illnesses, e.g. cystic fibrosis, schizophrenia or behaviours such as alcoholism/drug addiction or crime. Biological psychology is closely related to many other disciplines such as Biological psychology, health psychology, and psycho-pharmacology to name but a few. It is also a branch of neuroscience (the study of the nervous system), which itself combines elements of a number of subdivisions such as neuroanatomy, neurochemistry and neurophysiology. Biological psychology has close links with evolutionary history and psychology. The theory of evolution was proposed by Charles Darwin who stated that the strongest organisms with the best characteristics for survival reproduced more successfully and thus passed their survival characteristics to the next generation. This principle known as natural selection and it may apply to behavioural capacities, as they are mediated by the physical body which has evolved. Psychology: Biological Psychology (AH) 8

14 Biological psychology therefore concerns study of the following psychological processes: certain key concepts in Biological Psychology Neural and hormonal systems and behaviour Cortical functions Awareness Motivation Emotion Stress. This pack emphasises the three key concepts of neural and hormonal systems and behaviour, motivation and stress. The issues included are the use of non Human animals in Research and biological determinism. Psychology: Biological Psychology (AH) 9

15 INTRODUCTION: OVERVIEW ON BIOLOGICAL PSYCHOLOGY Biological psychology concerns the relationship between physiological processes and behaviour. Physiological processes refer to the way that the brain and nervous system are involved in behaviour and cognition. In this support pack, we will explore three key concepts in biological psychology: neural and hormonal systems and behaviour motivation, and stress. These three concepts have been selected as they illustrate many of the physiological processes connected to biological psychology such as genetics, the brain and nervous system, hormones and changes in growth and development. This unit will also investigate the role that physiology and biology play in everyday life. For example, how adequate are homoeostatic motivation theories as an explanation for human behaviour? In addition, complementary and opposing theories will be discussed. The Philosophical and Psychological Roots of Biological Psychology Psychology is a comparatively new discipline, dating only to the 19 th Century and the establishment of the first formal psychological laboratory at the University of Leipzig by Willhelm Wundt. Therefore, biological psychology as a separate and distinct discipline is comparatively young. However, the theory of biology as destiny was formulated many centuries ago. Psychology has philosophical and scientific antecedents. Biological psychology is no different. Somewhat surprisingly the brain has not always been considered as the location of mental activities. On the contrary Aristotle believed (rather romantically) that the heart controlled mental activity. The Bible took a more earthy approach mentioning the heart, stomach, liver and bowels, whilst omitting the brain. The Greek physician Hippocrates did not moot the idea that the brain was involved in behaviour until around 400 BC. In 1633 the philosopher Descartes proposed a theory which came to be known as dualism. Humans according to Descartes possess a non-material soul and a material body. Descartes believed that the mind and body were linked by the pineal gland. Modern biological psychologists reject this notion. It was not until the 20 th Century that biological psychology was born. Prior to this time scientists did not understand the manner in which the brain was related to the mind and the body. Scientific advances which resulted in the discovery of localisation of brain function led the psychologist William James (1890) to conclude that humans could be best understood by studying the nervous system. The 20 th century saw huge advances in biological psychology. Edward Thorndike demonstrated how to measure learning and memory in animals. Ivan Pavlov and B.F Skinner investigated the role of conditioned reflexes and reward systems in behaviour and Tolman demonstrated the existence of cognitive mind maps. Psychology: Biological Psychology (AH) 10

16 In recent years technological advances have greatly aided the study of biology psychology. CAT, PET AND MRI scanners have furthered our understanding of complex physiological and neurological systems. Biological psychology is still coming into its own and it is likely that the best is yet to come, and there is still some way to go before we have achieved a full understanding of the relationship between brain and behaviour. Biological psychology emphasises the importance of physiological processes in influencing human and animal behaviour. Psychology: Biological Psychology (AH) 11

17 KEY CONCEPTS IN BIOLOGICAL PSYCHOLOGY: NEURAL AND HORMONAL SYSTEMS AND BEHAVIOUR We will consider the following in relation to the study of neural and hormonal systems and behaviour: neurochemicals organisation and function of the endocrine system interaction of hormonal system and nervous system theories and research of hormonal influences on behaviour. The most important part of the human body is undoubtedly the nervous system. All human thought, behaviour, action and emotion are in some way controlled by this system. The nervous system is in effect a massive information processing system, capable of input, processing and output. Input is received from the outside world by means of sensory signals - taste, touch, sight, sound and smell. These details are processed, and categorised. Finally, the brain acts on the information by activating the muscles to take the appropriate action. But just how is this achieved? And which parts of the nervous system are involved in which actions? The first thing to be aware of when studying biological psychology is that the nervous system is actually comprised of two parts: the central nervous system and the peripheral nervous system. Each part is responsible for different functions, and working together, they mediate all bodily functions, thoughts, behaviours and emotions. Problems in any one area impact on the organism as a whole and inhibit optimum functioning. Specific Functions of the Nervous System The Central Nervous System (CNS) is the part of the nervous system which is encased in bone, namely the brain and the nervous tissue within the spinal cord. All information is sent to the central nervous system to be acted upon. The Peripheral Nervous System contains all nervous tissue that lies outwith the central nervous system. It contains two subsystems namely the somatic and autonomic nervous systems. The Somatic Nervous System acts as a two-way system carrying messages between (a) the sense organs and the CNS and (b) the CNS and the muscles of the body. Every movement made involves the somatic system. The Autonomic Nervous System carries messages between the central nervous system and the organs and glands of the body. This area of the nervous system carries out actions which are largely outwith conscious control, that is independent or autonomic. For example, when you turn over your exam paper and realise that you have studied all the wrong subjects then it is the autonomic nervous system which is responsible for making your heart beat just that little bit faster. Psychology: Biological Psychology (AH) 12

18 To further complicate matters the autonomic nervous system is divided into two parts - the sympathetic nervous system and the parasympathetic nervous system. The sympathetic system is involved in mobilising the body for action in times of stress, usually known as the fight or flight syndrome. The parasympathetic system is responsible for the regulation of bodily functions to conserve energy. The sympathetic and parasympathetic systems work together to provide the appropriate response at the appropriate time. The sympathetic and parasympathetic systems are closely linked to the endocrine system. Diagram of Nervous System How do these systems communicate with one another? In order to understand biological psychology it is necessary to understand a little about the mechanisms of the nervous system. For those of you who do not have a biology background this may appear a little tricky. However it is not as difficult as it sounds. Basically the nervous system is something like a vast computer system. Each area performs specific functions. If any area fails to function properly, it affects the organism as a whole. For example, the speed that a message is transmitted down an axon is dependent on whether the axon is covered with a myelin sheath or not. The sheath is made up of specialised glial cells. A condition known as multiple sclerosis (characterised by severe sensory and motor dysfunction), is a disease in which the body destroys its own myelin. Multiple sclerosis effects the cognitive, behavioural, emotional, psychological and physiological functioning of the individual. Perhaps the best way to approach this topic is to look at the similarities between the nervous system and that basic building block of life the cell. The nervous system like every other part of the body contains cells. Psychology: Biological Psychology (AH) 13

19 Similarities between cells of the Central Nervous System and other body cells 1. Both have semi-permeable outer membranes. 2. Both have a nucleus - which contains relevant genetic information. 3. Both contain a structure known as mitochondria which transforms glucose and oxygen into energy. There are two major types of cell in the nervous system: the neuron, and the glial. Each performs a specific function. The neuron transmits, receives and responds to signals. The glial aids the growth of the neuron, maintains the necessary chemical environment, repairs damage to the cell, helps bind neurons together and sends messages between neurons. In effect, the neuron is the racing driver and the glial the motor mechanic. Structure of the Neuron There are approximately 12 billion neurons within the nervous system, the majority of which are located in an area of the brain known as the cerebral cortex. They come in all different shapes and sizes. There are three types of neuron: the sensory (or afferent) which relays information from the sense organs to the central nervous system the motor (or efferent) which carry information from the central nervous system to the muscles and glands and interneurons (found only in the brain, eyes and spinal cord) which receive signals from sensory neurons and send impulses to motor neurons other interneurons. All neurons have long thin fibres which extend outward from the cell body. These fibres are known as either axons or dendrites. Each cell has only one axon, which itself may have many branches. The axon is responsible for carrying electrochemical signals away from the cell body. This electrochemical signal is known as the action potential. Hundreds perhaps thousands of elongated axons joined together are known as nerves. Each neuron can have many dendrites which themselves can have many branches. Dendrites act as a detector for signals coming from axons and other cell bodies and their role is to carry electrochemical signals to the neuron. Psychology: Biological Psychology (AH) 14

20 Diagram of Neuron In order for an electrochemical signal to travel down the axon, it is necessary to instigate changes within the neuron. In its resting state the neuron is electrically negative relative to the outside. Positively charged sodium ions cannot enter it. When an electrochemical impulse (action potential) occurs, the inside of the neuron momentarily changes from positive to negative, the sodium channels are opened and sodium ions flood in. This sets off a chain reaction, sodium channels open at adjacent membrane sites all the way down the axon. The temporary change in the potential of the axon is known as the action potential. The neuron is now said to have fired. Firing is something of an all or nothing affair. Cells either fire at full strength or not at all. For many years scientists believed that axons alone were capable of generating action potentials. However, recent research indicates that an action potential may begin in either the axon or dendrites. Action potentials which begin in the axon have the potential to go backwards (through the cell body and into the dendrites) or forwards (down the axon). In addition, it appears that action potentials, which spread from the cell body to the dendrites, enter only certain specific branches, possibly indicating that these messages are involved in strengthening connections between neurons. There is also a great variation in the speed of an action potential (ranging from 0.2 metres per second to approximately 120 metres per second). The speed of an action potential is dependant on two factors: 1. the presence of myelin 2. the diameter of the axon. Communication is fastest when it is transmitted via large, myelinated cells. These cells are most likely to be found in areas of the nervous system which carry the most urgently needed information. For example, sensory neurons which receive information via the environment are fast-acting myelinated cells. Although neurons fire in an all or nothing manner, they do have the ability to vary their rate of firing. For example, a neuron can fire repeatedly during the time that the sodium gates open. However, between each firing there will be a brief rest period, known as a refractory period. During these rest periods the gates for potassium open, temporarily re-polarizing the membrane. Psychology: Biological Psychology (AH) 15

21 When this happens the neuron can fire again. Current estimates indicate that a neuron can send action potentials via the axon at a rate of 1,000 per second. Neurotransmitters However, communication between neurons cannot be achieved by means of electrochemical signals alone, for two good reasons. Firstly, neighbouring neurons are separated by minute synapses or gaps. Secondly, certain substances necessary for communication (for example calcium and sodium) cannot enter the semi-permeable cell membrane without some help. In order for a neuron to communicate effectively with other neurons, it has to find a way to overcome these two problems. This is achieved by means of chemicals known as neurotransmitters which are stored in little pockets (known as vesicles) at the tips of axons. Once an electrochemical signal has travelled down the axon, and arrived at the terminal button, it stimulates the vesicles to discharge neurotransmitters into the synapse between the terminal button and the dendrite of the receiving neuron. The neurotransmitter then spreads to reach the next cell (also known as the postsynaptic cell). Once the neurotransmitter reaches the postsynaptic cell it binds to proteins known as receptors. Although each neurotransmitter fits or binds only with certain specific receptors, and each receptor recognises only one type of neurotransmitter, each neurotransmitter type can bind together to a number of different receptor types. Therefore, the same neurotransmitter can be involved in several different affects depending on the type of receptor to which it binds. Hundreds of new neurotransmitters are discovered every year, and each neurotransmitter can be: (a) excitatory (b) inhibitory, or (c) act to modify the receiving cell. Psychology: Biological Psychology (AH) 16

22 Classification of neurotransmitters 1. Amino acid transmitters - glutamate, aspartate, glycine Gamma-aminobutryic acid (GABA) 2. Monoamine transmitters - noradrenaline, adreanline, dopamine and serotonin 3. Acetylcholine 4. Neuropeptides. To recap, a neuron receives and transmits messages to neighbouring neurons by means of axons and dendrites. In its resting state the neuron cannot transmit messages. Therefore, changes to the environment have to take place. When an axon fires an electrochemical signal it temporarily changes the inside of the neuron from positive to negative, allowing sodium ions to rush in and causing adjacent sodium sites to open all along the membrane. The action potential shoots down to the end of the axon until it reaches the terminal button and causes the vesicles to release their neurotransmitters which then relay the message to neighbouring neurons. The channels which have opened up to allow sodium ions in then close releasing potassium ions out into the area surrounding the neuron and allowing it to return to its resting potential. Psychology: Biological Psychology (AH) 17

23 THE ENDOCRINE SYSTEM Communication between neurons is therefore achieved by means of electrochemicals and neurotransmitters. However, neurons are not the only cells, which use neurotransmitters to communicate with one another. Cells in the endocrine system (closely linked to the autonomic system) also make use of neurotransmitters. Though not quite as glamorous as the central and peripheral nervous system and certainly less sophisticated, the endocrine system plays a vital role in human behaviour. The endocrine system is responsible for a number of functions such as response to stress and physical growth. Communication between the cells of the endocrine system is achieved by secretion of chemicals known as hormones into the bloodstream. Hormones are rightly and wrongly blamed for many things, in everyday life. However, it is not true that only women possess hormones which cause them to nag, cry and generally act irrationally! In truth men and women possess the same hormones they merely have different amounts of each. For example, the average male has higher levels of the hormone testosterone than the average female. The average female tends to have lower levels of serotonin than the average male. Organisation and Function of the Endocrine System The endocrine system is the simplest form of communication system of the human organism. In effect the nervous system is the high flyer, the central nervous system the managing director and the endocrine system a lowly office junior. But like the office junior it does an awful lot of vital work. Hormones play an important role in determining metabolic processes, growth, sexual orientation, aggression, emotion and motivation. Hormones are secreted by the endocrine glands directly into the bloodstream. Some endocrine glands are activated by the nervous system; others are activated by changes in the internal chemical state of the body. There are three specific types of hormonal communication: Autocrine communication releases a hormone which acts on the cell releasing it Paracrine communication diffuses chemicals to neighbouring cells, and Endocrine communication occurs when the hormone is taken up by selected target organs. Hormones can only affect cells with receptors which recognise that particular hormone. Unlike neural communication, hormonal communication is comparatively slow and longer-lasting in its effects. Hormones are produced in short bursts and they are influenced by biological and environmental factors. Each has different effects on different tissues, organs and behaviours. Psychology: Biological Psychology (AH) 18

24 Major Endocrine Glands and their Role Hypothalamus controls the pituitary gland. Pituitary Gland regulates growth, and controls the thyroid, reproductive, pancreas and adrenal cortex glands. Regulates water and salt mechanism. Thyroid controls the metabolic rate Pancreas regulates sugar mechanism and controls glucagen and insulin rates. Testes/ovaries affects physical development, reproductive organs and sexual behaviour. Adrenal Medulla prepares the body for action - secretes adrenaline and noradrenaline. Adrenal Cortex regulates carbohydrates and salt metabolism. Releases corticosteroids involved in resistance to stress. Some Major Glands of the Endocrine System Psychology: Biological Psychology (AH) 19

25 Differences between Neural and Hormonal Communication 1. Neural communication involves rapid electrochemical messages between specific anatomical connections. Hormonal communication is slower and the messages are sent throughout the body via the bloodstream. 2. Neural communication is more likely to be under the control of the organism than hormonal communication. Similarities between Neural and Hormonal Communication 1. Neurons and hormone glands both produce and store their chemicals for release at the appropriate time. 2. Neurons are stimulated to produce an action potential/endocrine glands are stimulated to secrete hormones into the bloodstream. 3. Some chemicals act as neurotransmitter and hormone. 4. Neurotransmitters react to receptor molecules on the postsynaptic membrane; hormones react on the surface or inside of the target cell. 5. Certain hormones and neurons are capable of releasing more than one message. Interaction between the Nervous System and Hormonal System Hormonal communication occurs within the endocrine system. However, the endocrine system is influenced by the hypothalamus. The brain in addition to being a major target organ of the endocrine system is also responsible for the control of the release of hormones, sometimes directly, sometimes indirectly. For example, hormones are instrumental in the human fight-or-flight response. In this instance, neurons in the hypothalamus respond to stress by secreting a substance called corticotropin-release factor (CRF). The CRF stimulates the pituitary to release adrenocorticotropic hormone (ACTH). ACTH travels through the bloodstream to the adrenal glands and various other organs of the body, along the way some 30 other hormones, vital to ensure that the body responds to an emergency are released. The adrenal gland working together with the sympathetic branch of the autonomic nervous system releases adrenaline (epinephrine) which causes the blood vessels in the stomach and intestine to contract and the heart to beat faster. At the same time the adrenal gland releases noradrenaline (norepinephrine) which travels to the pituitary gland and stimulates it to release a hormone which acts on the outside layer of the adrenal gland. This second hormone stimulates the liver to increase blood sugar and raise energy levels to prepare the body for fight or flight. Communication between the neural and hormonal systems occurs in a cyclical fashion. Neurons can stimulate the release of hormones and vice versa. Messages are sent back and forth at a phenomenal rate. Working together these two communication systems ensure that we are equipped to deal with any emergency. Hormones however do not only prepare us to take emergency action. Hormones play an important role throughout our lifespan. A brief overview of the main functions of hormones follows. Psychology: Biological Psychology (AH) 20

26 Gonadal Hormones Almost all reproductive behaviour is dependent on hormones. The gonadal hormones androgen and estradiol released prenatally (about 12 weeks gestation) determine whether the infant is male or female. Then prior to puberty the hypothalamus stimulates the pituitary to increase the amount of growth hormone into the bloodstream. Cells of almost all body tissue are duplicated. The pituitary gland releases a hormone that stimulates the testes to secrete testosterone and the ovaries to secrete oestrogen and progesterone, which facilitates the development of secondary sex characteristics, menstruation and the bodily changes which occur during pregnancy. In middle adulthood the production of the female sex hormone oestrogen declines eventually triggering menopause. Disorders associated with Sex Hormones Androgenital Syndrome, a condition caused by an excess of testosterone during the development of a female foetus. Androgenital syndrome results in biological females whose external genitalia resemble that of a male. Testosterone Insensitivity. This condition occurs when the foetus does not respond to testosterone. Chromosomally an individual suffering from this condition is male but their external appearance is that of a female. Adrenal Hormones The adrenal glands (located in the kidney area) play a vital role in neural functioning and the ability to deal with stress. The adrenal gland comprises two parts - the outer layer (cortex) and the inner core (medulla). The cortex is controlled by the pituitary, and the medulla by the sympathetic nervous system. The cortex releases adrenal steroids which aid the synthesis and storage of glucose in the blood enabling it to take quick action. The medulla releases epinephrine and norepinephrine into the bloodstream thus reinforcing, sustaining and supplementing energy release. Disorders of the Adrenal Cortex/Medulla A deficient adrenal cortex may result in Addisons disease. This disease generally occurs in middle age and is more common in men than women. Symptoms include: lack of energy exhaustion apathy irritability, and lack of concentration. As the disease progresses the sufferer may begin to experience hallucinations, disorientation and delusions. If left untreated this condition can be fatal. Psychology: Biological Psychology (AH) 21

27 A hyperactive adrenal cortex often manifests as Cushings disease (caused by an excess of cortisol). Symptoms of this disorder include: obesity hypertension increased blood pressure anxiety depression fatigue memory and cognitive deficits. This condition can be treated successfully. Adrenal steroids are also thought to play a role in mental illness but the exact mechanism is not as yet known. Thyroid Gland The thyroid gland is responsible for the production of thyroxine. Thyroxine is released during periods of emotional excitement. It aids energy release, raises alertness, heart rate and body temperature. It is also involved in the development of the nervous system prenatally. Disorders of the Thyroid An overactive thyroid gland at or near the time of birth can result in severe mental and physical retardation. This condition is known as cretinism, and sufferers are often deaf-mute, have no secondary sex organs and exhibit severe mental impairment. Fortunately this condition can be prevented by the administration of thyroxine, at or near the time of birth. Hormonal over-stimulation of the thyroid also causes Grave s disease a condition which causes rapid weight loss, anxiety, fatigue and irritability. A deficiency of the thyroid causes myxoedema (mix-o-de-ma) which causes the sufferer to become depressed and suffer a loss of appetite and energy. Pituitary Gland The posterior pituitary gland is directly controlled by the hypothalamus, and produces antidiuretic and oxytocin hormones. Antidiuretic hormone controls urination and the level of water in body cells. Oxytocin is involved in the birth process, facilitating uterine contractions and milk production. The anterior pituitary is influenced by other endocrine glands. It releases 6 hormones: the stress hormone (ACTH) thyrotrophic hormone gonadotrophic hormone somatotropic hormone lactogenic hormone, and melanophore hormone. Psychology: Biological Psychology (AH) 22

28 Disorders of the Pituitary A deficiency of antidiuretic hormone causes diabetes insipidus. Obviously any problems with the endocrine system as a whole will have an effect on the release of the named hormones above and the functioning of the organism as a whole. Theories and Research of Hormonal Influences on Behaviour Neural and hormonal communication systems play a vital role in human behaviour. They help make us what we are. They determine our biological sex, our physical growth and play a part in our mental and physical health. But is this the whole story? Early theorists believed that biology is destiny by this they meant that an individual s genetic inheritance, biological sex and hormonal make up determined who they were. In short they believed there to be certain innate and therefore natural differences between the genders. Contemporary textbooks often refer to this as the mamawaw theory ( men are men and women are women ). This is known as the biological approach and it was very popular for a long time. But how valid is it? Let us look at a few examples. Aggression As we said at the beginning, biological psychology has its basis in evolutionary psychology and ethology. Therefore, animal behaviours are of great interest to biological psychologists. Evidence exists to support the idea of a biological basis for aggression in lower species. Experimental research undertaken by Smith, King & Hoebel (1970) showed that stimulation of the hypothalamus in lab bred rats could cause the rat to kill a mouse which shared their cage. The rats killed the mice in exactly the same way as a wild rat would, despite never having seen this behaviour and showing no aggression to the mice previously. This process was also turned on its head. The rats who had spontaneously killed the mice after their hypothalamus had been tampered with were then given an injection of a neurochemical blocker into the hypothalamus. They then became (temporarily at least!) peaceful. This experiment indicates that aggressive behaviour involves some innate reactions. In higher order animals, instinctive patterns of aggression are influenced by the cortex rather than the hypothalamus and aggressive behaviour is a result of biology and environment. In humans a biological factor often linked to aggressive behaviour is the hormone testosterone. Social aggression in most cultures is much more common in men than women. Genetic males are exposed to testosterone in the womb, which has led to the theory that testosterone somehow masculinises their brain, and provides a blueprint for aggressive behaviour to be reactivated at puberty when testosterone levels are high. There is some support for this theory in animals. Mice who have been castrated when young are not aggressive when adults, and adult mice if castrated cease to be aggressive. Psychology: Biological Psychology (AH) 23

29 However, research by Albert, Walsh & Jonik (1993) has shown that increased testosterone levels at puberty have no impact on the behaviour of human males, and that castration does not reduce aggressive behaviour. A large scale study undertaken by Dabbs & Morris (1990) in which over 4000 male veterans were tested for aggressiveness indicated that males who had the highest levels of testosterone in their blood were the most likely to have a past history of aggression. Studies by Archer (1991) have indicated that violent criminals have higher levels of testosterone in their blood than non-violent criminals. However, it is likely that it is aggressive encounters which increase testosterone levels and not the other way round. Other Possible Explanations Biosocial Theory - states that behaviour is a product of biology and environment. This theory highlights the fact that boys and girls are treated differently from birth and that boys are encouraged to be unemotional, aggressive and competitive. Girls are encouraged to be compliant, placid and nurturing. Assertive behaviour is encouraged in boys. However, biosocial theory acknowledges that there are certain innate biological differences between genders. For example, research by Moss (1967) indicates that baby boys are generally more irritable than baby girls. It is likely that these innate differences are instrumental in influencing parents and society, so that the infants are then treated differently, thus resulting in greater differences in behaviour. Biosocial theory is closely linked to social learning theory. Social Learning Theory (SLT) - states that aggressive behaviour is a learned response. It views aggression as one of several possible reactions to frustration. Aggression is not a biological drive but a cognitive-emotive choice based on past experience and the likely outcome of the behaviour. Notable psychologists in this field include Bandura and Bronfrenbrenner. According to SLT individuals aggress if this behaviour has a positive-incentive for them. For example, if a child s aggressive behaviour is rewarded by significant others it is likely that this behaviour will be repeated. The reward acts as a positive reinforcement. Conversely, if acting aggressively protects the child from a negative consequence then aggression has been negatively reinforced. SLT maintains that we learn via observational learning, and that individuals imitate or identify with appropriate others. If the other is aggressive then we are highly likely to adopt such behaviour. Recent developments in the field of forensic (criminal and legal) psychology support this theory. Carpenter (1990) has undertaken research regarding the increase in aggression by females. She maintains that this is due to the fact that women are choosing to identify with male rather than female role models; females increasingly view aggression as a way to achieve goals and status. Durkin (1995) also found that girls are often more aggressive than boys, particularly when indirect non-physical aggression is being measured. Psychology: Biological Psychology (AH) 24

30 Sex and gender The biological approach to sexual orientation states that the differences between men and women are a result of: 1. genetic differences 2. hormonal differences, and 3. the process of sexual differentiation. Again research with animals supports the concept of a biological base for sexual orientation. Experimental work with rats by Dorner (1968), has shown that if you remove a small part of a newborn male rats brain it will then act as a female rat would. Research undertaken by Imperato-Mcginley et al (1974) provides tacit support for the view that biology determines human sexual orientation in humans. In this remarkable case four children from the Batisto family spontaneously changed sex from female to male when they hit puberty. In total, thirty seven children from the same village as this family changed sex. All of the children had a common ancestor who is thought to have passed on a mutant gene. Whilst in the womb these children developed normally, their neural system was exposed to testosterone at around twelve weeks and they ought to have been born boys. However, one vital component was missing. The boys received testosterone but they did not receive the hormone dihydrotestosterone (di-hi-dro-test-tost-er-own). Without this, their external genitalia could not develop. When they hit puberty however the increased amount of testosterone secreted produced enough dihydrotestosterone to change their external appearance. All of the children involved have successfully adapted to their change of sex and have taken on male roles, and have married women. However, it is important to note that the individuals transition has been eased by the support they have received from their family and community regarding their new male identity. However, the cases of Mrs Went and Mr Blackwell refute the idea of biologically based sexual orientation, (Goldwyn, 1979). Mrs Went suffered from a condition known as testosterone insensitivity. In the womb she developed initially as a male, and developed testes. The testes secreted their first hormone and the female genitalia disappeared. However, when the testes produced testosterone the foetus did not respond to it. Mrs Went has no womb cannot menstruate and therefore cannot bear children. Chromosomally she is male, although her external appearance indicates that she is female. She has chosen to live as a female. Mr Blackwell was born a hermaphrodite (an individual born with both female and male genitalia). At puberty he developed breasts, menstruated and ovulated. Exploratory tests revealed that he possessed one active ovary and one active testicle. Mr Blackwell expressed the wish to be male and had surgery to remove his female parts. Mr Blackwell has chosen to live life as a man. Further criticism of the biological basis of sexual orientation can be found in the case of transsexuals (individuals who are born equipped with fully functioning male or female genitalia, who are socialised in the appropriate role and who are biologically capable of reproduction yet who believe themselves to have been born in the wrong sex). Psychological tests have shown that male to female transsexuals are more like biological females and female to male transsexuals are more like biological males. Psychology: Biological Psychology (AH) 25