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Biological Psychology Lecture 1- Introduction

What is biological psychology?  Psychophysiology- the study of the relationship between physiological and psychological phenomena and the way in which the mind and body interact  Neuroscience- psychology that deals with the structures and functions of the nervous system and brain  Psychopharmacology- the branch of psychology concerned with the effects of drugs on the mind and behaviour Short history of neuroscience  Early brain surgery already around in 6500BC  Hippocrates: “brain involved in sensation and is the seat of intelligence”  Aristotle: “heart is the centre of intellect; brain is for cooling the blood”  Galen: found a dissociation between the cerebrum and cerebellum through studying a sheep’s brain  Renaissance period: viewed body as a hydraulic machine, muscles are pumped up by fluids coming from the brain, going through the nerves  Descartes: brain mechanisms control behaviour that does not go beyond that of animals. Additionally, there is a ‘God-given’ soul or mind- the mind receives sensations and commands muscles by communicating with the brain via the pineal gland  Brings about the idea of dualism/monism Dualism= ‘mind’ and ‘brain’ both exist separately Monism= the mind is not a separate entity, it is simply brain activity Neuroscience after the renaissance  Observation of grey and white matter  Grey matter= highly concentrated of nerve cell bodies  White matter= mostly nerve fibres

By the end of the 18th century  Discovery of the central nervous system (CNS) consisting of the brain and spinal cord  Discovery of the peripheral nervous system (PNS) consisting of all the nerves and nerve cells outside of the brain and spinal cord  Observation that there are certain brain areas that have a specific function with small interindividual variance- this was the beginning of human brain mapping

Major directions of neuroscience today  Molecular neuroscience= most basic level, investigating the role of difference molecules e.g. during communication between nerve cells, conducting nerve cell growth etc.  Cellular neuroscience= investigating the types and properties of different single brain cells and their interactions  System neuroscience= investigation of brain circuits and their clustering together to form brain systems that have a certain function e.g. the visual system/the motor system  Behavioural neuroscience= investigating the joint work of brain systems and relating it to behaviour  Cognitive neuroscience= aims to find out how higher mental activities such as thinking, language etc. are implemented in the brain Ethical considerations in biological psychology  The ‘minimalist’ position= animal research is accepted under certain conditions depending on the value of the research, distress to the animal and type of animal  The ‘abolitionist’ position= there is absolutely no acceptable form of animal research because animals have the same rights as humans, keeping animals for research is the equivalent to slavery, killing animals for research is murder Controlling animal research  Institutional Animal Care and Use Committee (IACUC)- consists of committee members from difference scientific backgrounds who control the keeping and research of animals in institutions  When you plan an experiment on animals you need to submit your research proposal to the IACUC who decides whether your experiment has got: o the potential to answer important questions o is necessary or there are alternatives (replacement) o minimises animal distress (refinement) o finds a way to use the fewest animals possible (reduction) Avoiding extensive use of animals  Use a minimal number of animals e.g. in many neuroscience studies only 2 monkeys are tested  Use the same individuals for a number of different studies  Create computational models based on animal data to simulate neural activity Biological Psychology Lecture 2- Brain Cells Types of brain cells

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In the brain there are 1 trillion brain cells 10% of these are neurons which are electronically active, information processing and the ‘master’ cells of the brain 90% of brain cells are glia which are like a glue between neurons, are insulating, nourish neurons and are known as the ‘servants of the neurons’

Classification of neurons  Unipolar= only one neurite is attached to the soma (cell body). There is no dendrite at the soma, only an axon. E.g. sensory neurons  Bipolar= 2 neurites (1 dendrite + 1 axon) are attached to the soma. E.g. neurons of the retina  Multipolar= many neurites (many dendrites and 1 axon) are attached to the soma  Unipolar and bipolar neurons make sense because taking up only a very small amount of information can lead to greater precision- uni and bipolar neurons are most often sensory neurons Types of multipolar neurons  Stellate cells (stellate=star-like)- very tight network of dendrites, perfect for interconnection and information exchange between neighbouring neurons  Pyramidal cells- dendrite tree with similar shape like a pyramid- relatively long axon, perfect for transferring information across long distances (e.g. from brain to spinal cord) The soma  Soma= cell body  Consists of the nucleus (contains DNA), mitochondria (energy supply), endoplasmatic reticulum and ribosomes (produce proteins), golgi apparatus (segregation of proteins) and cell membrane (regulates ionic flow)  Transcription and translation occurs in the soma  Transcription= DNA contains the building plan for all cells in the body, it is the blueprint for RNA (an inverse of DNA) and mRNA exits nucleus  Translation= using mRNA, ribosomes produce proteins which are used for building and renewing the cell, mRNA is translated into proteins Cell membrane with ion channel  Cell membrane- electrical activity of neurons mainly achieved by ion channels in the membrane  Hydrophilic or polar head contains phosphates which attract water  Hydrophobic or non-polar tail contains hydrocarbons which reject water  These form the phospholipid bilayer of the cell membrane  Driven by diffusion, ions tend to equally distribute in the brain. If there is a difference in concentration of ions between inside and outside the cell, ions want to move from high concentration to low concentration. The difference is called the ‘concentration gradient’  The cell membrane is semi-permeable (only certain ions can go through). K+ moves outside of the cell and anions (negatively charged ions) remain inside the cell. When they are outside the cell, the inside of the cell is more positively charged and vice versa  The equilibrium potential= the membrane potential at which no K+ ions are moving across the cell membrane because attraction of negativity inside the cell and K+ concentration outside the cell are equal

Resting potential of neurons  Many different ions are inside and outside of the cell body e.g. potassium, sodium, chloride, calcium  All have a different equilibrium potential  The most influential ions are K+ (around -80mV) and Na+ (around 62mV)  Neurons resting potential is somewhere between -80 and 62 mV

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The cell membrane is 40 times more permeable for K+ and Na+ The resting potential of most neurons is around -65mV

What does this have to do with psychology?  If we don’t understand the mechanisms leading to a negative membrane potential, we will not understand mechanisms associated with the activation of neurons  If we do not understand the activation of neurons, we will not understand how the brain processes information  If we do not understand how the brain processes information, we will not understand how we think, feel etc. Pathologies associated with deviant ion channel properties  In certain forms of epilepsy, genetic mutations coding K+ channels have been found which leads to altered membrane resting potential and this alters the excitability of the brain  Observations of mice with genetic defects leading to malfunctioning K+ channels in the cerebellum show the mice have difficulties in motor control  Genetic defects leading to overexpression of Na+ channels leads to hyperexcitability of sensory neurons which can lead to increased sensitivity to pain Inside of axons  There are hardly any ribosomes so there is very little/no protein synthesis in the axon, most of the proteins present in the axon come from the soma  The cytoskeleton comprises the microtubule and microfilament (organisation of intracellular structure and transport) and the neurofilament which is essential for axonal growth  Research has shown the cytoskeleton is altered in Alzheimer’s disease patients- the microtubules are clashed which leads to neurofibrillary tangles which means information cannot be transmitted anymore- leading to the symptoms of Alzheimer’s Dendrites  Axon terminals from other neurons make contact with the dendrites which are like the ‘antennas’ of the neuron.  They take up chemical signals from pre-synaptic neurons and carry on electrical signals  Dendritic spines increase possible synaptic contact sites between neurons, they are very effective synapses that can quickly change in appearance. They are also important for plasticity and learning. Also, ribosomes can be found in dendritic spines- important for protein synthesis for quick structural changes of the spines (associated with Santiago Ramon y Cajal) Glia      

Make up 85-90% of cells in the brain, they fill in space between the neurons. Little is known about their function Different types= astrocytes, oligodendrocytes, Schwann cells and microglia Astrocytes (star-like)- influence neurite growth, regulate chemical content in extracellular space Oligodendrocytes- insulate axons in the CNS by supplying a myelin sheath Schwann cells- insulate axons in the PNS by supplying a myelin sheath Microglia- remove dead neurons and glia and regulate synaptic plasticity Biological Psychology Lecture 3- Neuroanatomy

Neuroanatomical terms  Neuraxis, dorsal, ventral, rostral, caudal  Inferior-superior (ventral-dorsal)  Anterior-posterior (rostral-caudal)

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Medial-lateral Proximal-distal

Organisation of the nervous system  CNS is the nerves of the brain and spinal cord  PNS is the nerves outside of the brain and spinal cord  PNS is split into two parts: somatic nervous system (responsible for voluntary control/senses) and the autonomic nervous system (responsible for subconscious body control e.g. heart rate, respiration rate, digestion, salivation etc.) Structure of the brain Hindbrain Midbrain Forebrain

Brainstem

Hindbrain  Cerebellum- movement control, body position  Pons- main switchboard to the cerebellum  Formatio reticularis- 90+ nuclei, regulates activity and sleep  Medulla oblongata- reflex control centre e.g. heart rate, blood pressure, breathing, swallowing etc.

Midbrain  Superior colliculus- visual processing  Substantia nigra and red nucleus- both responsible for voluntary movement control  Inferior colliculus- auditory processing  Tectum (dorsal part of midbrain) and tegmentum (ventral part of midbrain) Forebrain

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Thalamus (Greek: inner chamber)- gateway of the cortex, all sensory pathways (except olfaction) relay in the thalamus before terminating in the cerebral cortex Cortical folding- increases brain surface, the degree of cortical folding is correlated with intelligence: more folds=more intelligent Gyri- convolutions or bumps, protruding rounded surfaces, part of cortical folding Sulci- valley between gyri or enfolded regions that appear as surface lines, part of cortical folding Fissure- a very deep sulcus, part of cortical folding Longitudinal fissure- also known as the interhemispheric fissure as it divides the 2 hemispheres Basal ganglia- associated with motor control, choosing the right action

There are also 4 lobes located in the forebrain: o o o o

Frontal lobes= ‘executive’ brain, planning and guiding behaviour, moral judgement Temporal lobes= language processing, Wernicke’s area, long term memory, knowledge Parietal lobes= association cortex, integrates sensory information from multiple modalities Occipital lobes= dedicated entirely to vision as this is one of the most complex senses

The limbic system  Involved in emotional regulation, learning and memory, emotional memories and recognition of emotions in other people  Structures include the hypothalamus, hippocampus, amygdala and cingulate cortex  Hypothalamus= regulates hormones, controls food and fluid intake  Hippocampus= establishing memories, new contextual learning, memory retrieval, understanding spatial relations  Amygdala= coordinates behavioural, autonomic and endocrine responses to environmental stimuli, especially those with emotional content e.g. fear, no amygdala= no fear Other structures in the forebrain  Corpus callosum (Latin: hard/rigid)- largest white matter structure in the brain, 200-250 million contralateral axonal projections, major fibre connection between the hemispheres  Cerebrospinal fluid- buoyancy aid, allows the brain to maintain its density without being impaired, also provides protection- protects the brain tissue from injury when the skull is jolted, also allows for homeostatic regulation  Hydrocephalus (water on the head)- cerebrospinal fluid can build up, putting pressure on the brain, this usually occurs in infancy (called congenital hydrocephalus) but can also occur after head injury or brain cancer Brodmann areas  The 47 different areas of the cerebral cortex that are associated with specific neurological functions and distinguished by different cellular components  They are the specific occipital and preoccipital areas of the human cerebral cortex, distinguished by differences in the arrangement of their six cellular layers, and identified by number  They are considered to be the seat of specific functions of the brain Biological Psychology Lecture 4- Action Potentials and Synaptic Transmission Resting membrane potential  Ion channels and sodium-potassium pump are the 2 major players in RMP  Ion channels- Na+ wants to go inside the cell but Na+ channels are closed, K+ wants to go outside of cell but is attracted by the negativity inside the cell. Chemical force (concentration gradient) pushes K+ outside of the neuron, electrical force pulls K+ back inside

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RMP of most neurons = around -65mV Synaptic input can make cell membrane and soma more positive or negative (depending on currency of input) Cell membrane will return to RMP unless the membrane reaches its threshold which is around -40mV in most neurons This will trigger generation of an ACTION POTENTIAL

Action potentials  Is initiated in the axon hillock  Na+ channels close  K+ channels open completely, K+ streams out of cell, returns cell membrane to negativity  Synaptic input makes membrane potential less and less negative  Na+ channels open and Na+ rushes into cell, making cells inside positive  Sodium-potassium pumps re-establish resting potential Refractory period  Absolute refractory period= no action potential can be initiated  Relative refractory period= only very strong input can initiate an action potential Speed of action potentials  The thicker the axon, the more ions can move down inside its membrane  Action potential adjacent Na+ channels can be opened earlier  This makes action potential propagation faster  Squid giant axons can be up to 1mm thick (in the human brain there is not enough space for such thick axons)  Myelinated axons are much faster than non-myelinated axons- myelinated= up to 100m per second, non-myelinated= up to 1m per second  Myelination speeds up the action potential= no myelin sheath- 1m/s, 50% myelinated- 4m/s, 90% myelinated- 20m/s, 98% myelinated- 100m/s  Some diseases associated with loss of myelin sheath= multiple sclerosis, Guillain-Barre syndrome and Devic’s disease Propagation of the action potential  Action potential only travels down the axon  It never returns back up the axon, only a one-way journey  After a patch of axon membrane has been at the AP the membrane needs some time to restore- Na channels cannot open and sodium-potassium pumps must restore resting membrane potential (refractory period) How is information coded by neurons?  All or nothing law- every action potential of a neuron is identical and it either gives impulse or gives no impulse but nothing in between  Firing rate= number of action potentials per time intervalnc  Electrical synapses- gap-junctions  Chemical synapses- including neuromuscular junctions How do chemical synapses work?  Vesicle is docked at active zone  Action potential arrives, voltage gated Ca+ channels open  Ca+ leads to fusion of vesicles within cell membrane (exocytosis- neurotransmitters are released into cleft)

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Neurotransmitter causes transmitter-gated ion channels to open- Na+ rushes into cell, depolarisation occurs if strong enough new action potential is triggered Used vesicles are recycled (endocytosis)

Excitatory vs. inhibitory synapses  Transmitter-gated ion channels are open for Na+ ions  These make the inside of the cell more positive  This drives the action potential towards excitation  Leads to excitatory post-synaptic potential  Transmitter-gated ion channels are open for Cl- ions  These make the inside of the cell more negative  This drives the action potential towards inhibition  Leads to inhibitory post-synaptic potential  This also makes initiation of an action potential less likely Important principles of chemical synapses  A chemical synapse can either be excitatory or inhibitory- never both at the same time  Unidirectional- information flows from pre to post synaptic cell (not backwards)  Different synapses can be differently effective depending on site of synapse, neurotransmitter used and ion channels activated by neurotransmitter Synaptic integration  It would be inefficient is action potentials were not automatically passed on to the next neuron  Most neurons in the brain are connected to hundreds of thousands of other neurons  All or nothing principle- action potentials will go to all neurons receiving info from this cell  Not all of these neurons are meant to generate an AP  Only those which get additional AP’s are particularly responsible for initiating AP  This way information processed in the brain will be co-ordinated  If every AP was passed on to every neuron this would lead to over-excitation which could cause a seizure

Biological Psychology Lecture 5- Neurotransmitters What is a neurotransmitter?  A chemical that is found/synthesised in the presynaptic neuron  Is released by the presynaptic neuron when it is stimulated  It acts on a post-synaptic receptor and causes a biological effect  It is rapidly inactivated by a reuptake mechanism or enzymatic degradation

Types of neurotransmitters Type

Neurotransmitters

Amino acids

Glutamate Gamma aminobutyric acid (GABA) Aspartate Glycine

Biogenic amines

Dopamine Adrenaline Noradrenaline Serotonin

Acetylcholine

Acetylcholine

Soluble gases

Nitric oxide (NO) Carbon monoxide (CO)

Neuropeptides

Endorphins Neuropeptide Y Substance P

Glutamate  The primary excitatory neurotransmitter  Found in 75-80% of synapses  Specific, information carrying cells  Information that is learned and remembered is transmitted by neurons secreting glutamate GABA    

The primary inhibitory neurotransmitter Found in 15-20% of synapses Specific, inhibitory action cells Glutamate’s ‘rival’

Acetylcholine (ACH)  Main neurotransmitter in the PNS and neuromuscular system  2 main receptor types: nicotinic receptors (ionotrope, neuromuscular junction) and muscarinic receptors (metabotrope, CNS)  Active in maintaining EEG wakefulness  Cholinergic neuron lesions impair attention  Death of cholinergic neurons and decrease in ACH related to Alzheimer’s dis...