Unit 1 Psychology AOS 1: How does the brain function?

Unit 1 Psychology AOS 1: How does the brain function?

1. The role of mental processes and behaviour

   • Approaches over time to understanding the role of the brain, including phrenology, first brain experiments and neuroimaging techniques
     • Development of psychology
       • Phrenology - the relationship between features on the surface of a skull and a person’s characteristics.
         • Franz Gall - different parts of brain have different functions
           • localisation of brain function - the size of the area on the skull was how developed was also the amount of influence a characteristic is
           • Spurzheim furthered his work by developed ‘faculties’. There were originally 27 but updated to 35.
             • • Affective = Feelings (Destructiveness, hope, self-esteem) • Intellectual = Perceptive (Time, melody, language)
     • Brain Experiments
       • Electrical stimulation of the brain = initiate or inhibit activity in the brain using an electrode
         • Penfield mapped the cortex, using epilepsy patients using this
       • Brain ablation = disabling/destroying/removing selected brain tissue and assessing behavioural changes
         • • Flourens removed small bits of cortex to observe recovery, understanding of a holistic view of the brain
         • Lashley theories
           • Lashley = a healthy part of cortex can take over function of damaged area
           • Lashley = Mass action theory that large areas of brain that can function in complex functions
       • Corpus callosum = a bundle of nerves that connects the left and right cerebral hemispheres and serves as the main communication pathway
       • Hemispherical specialisation: Left controls language and logical thinking, right controls visual-spatial awareness
         • Communicate through the corpus collosum to create a coordinated response
         • Sperry and Gazzinga’s Split Brain Experiment
     • Neuroimaging Techniques
       • Structural = produces scans to look at the brain structure and anatomy
       • Functional = analyse a function of the brain ‘at work’ and brain structure
   • The basic structure and function of the central and peripheral nervous systems and the body’s internal cells and organs
     • Nervous system functions by receiving, processing and coordinating a response to information.
       • CNS and PNS
         • Central nervous system (CNS) consists of the brain and spinal cord.
         • Peripheral nervous system (CNS) consists of the network of nerves outside CNS.
           • Sympathetic and parasympathetic responses
             • Sypathetic
               • Pupils dilate, HR increase, Increase perspiration
             • Parasympathetic
               • Pupils contract, HR decrease, Decrease perspiration
   • The role of the neuron, and the role of glial cells in supporting neuronal function
     • Neuron is an individual nerve cell. Specialised to receive, process and/or transmit messages.
       • Sensory neurons located in the PNS and send sensory information to the CNS. They are specialized to respond to a stimulation
       • Motor neurons carry messages from CNS to cells in skeletal muscles/organs/glands
       • Interneurons are connecting neurons and are in the CNS only.
       • Parts of the Neuron
         • Dendrite receives information from a nearby neuron.
         • Soma is the cell body which combines information from the dendrites and sends it to the axon.
         • Axon transmits information from the soma towards axon terminal.
         • Axon terminal hold and release neurotransmitters substance.
         • Axon terminal hold and release neurotransmitters substance.
         • Myelin is the white and fatty substance that insulates an axon increasing speed of neural transmissions
         • Myelin sheath protects against interference from nearby neurons. It is not continuous and is separated by small gaps called nodes of Ranvier.
     • Glial cells are specialised cells that are involved in insulation, nutrients, repair and eliminate waste in the nervous system.
     • Synaptic transmissions
   • Structure and function of the brain
     • Forebrain higher order thinking such as thinking, learning, memory, perception,
       • Hypothalamus: maintains homeostasis and regulates pituitary gland (hormones)
       • Thalamus: filters information from sense receptor sites (except the nose), and directs it to the appropriate lobes
       • Cerebrum: made up of the four lobes
     • Midbrain controls functions such as movement; processing of: visual, auditory information, sleep and arousal (‘alertness’)
       • Reticular formation is a network of neurons that runs through the centre of the midbrain, hindbrain and brain stem towards the forebrain.
         • Reticular activating system (RAS) screens incoming sensory information and regulates arousal
     • Hindbrain controls motor function and vital and automatic responses such as breathing + heart rate + sleep + arousal
       • Pons is involved with sleep, dreaming and arousal
       • Medulla controls vital body functions
       • Cerebrum coordinates movement, balance and precision
   • The role of the cerebral cortex
     • Cerebral cortex is divided into 4 lobes
       • Frontal Lobe function is to initiate and execute voluntary motor activity, planning and speech
         • Primary motor cortex responsible for the planning, initiation and performance of specific movements
         • Broca’s area responsible for articulate speech
       • Parietal Lobe receives and processes sensory information
         • Primary somatosensory cortex receives and process sensory information from the skin and body parts.
       • Temporal Lobe processes auditory perception and has a role in memory, visual perception including facial recognition and emotional responses to sensory information.
         • Primary auditory cortex receives and processes sound from both ears
         • Wernicke’s area is responsible for speech comprehension and interpreting the sounds of human speech
       • Occipital Lobe receives and processes visual information
         • Primary visual cortex is the largest area of the occipital lobe and responsible for processing visual information

2. Brain plasticity and brain damage

   • Development and changes in brain structure and function
     • Development
       • Myelination is the growth and development of myelin
       • Synaptogenesis is the formation of new synapses between the brain’s neurons.
       • Synaptic pruning is a process where synaptic connections are eliminated which is designed to fine tune the neural connections
     • Neural pathways and connections
     • Frontal Lobe development
   • Brain Plasticity = the ability for the brain to change in response to experience
     • Adaptive plasticity is the ability of brain to compensate for loss of function or maximize the remaining functions
       • Rerouting = undamaged neuron that has lost a connection will seek a new active neuron
       • Sprouting = growth to form new connections. This process involves rerouting
   • Developmental plasticity is the development and consolidation of neural pathways in the foetal stage as well as in babies, children and adolescents
     • 1. Proliferation = A foetus’s cells develop into neurons. Approx. 250,000/min
       • 2. Migration = newly formed neurons move outward to their destination. The neuron’s role is determined by its location.
         • 3. Circuit formation = axons of new neurons grow out to target cells and form synapses with them.
           • 4. Circuit pruning = elimination of excess synapses and neurons
             • 5. Myelination
     • Sensitive period is a time when an organism is more responsive to certain stimulation
     • Critical period is a narrow period where in development an animal is preprogrammed for learning to occur
   • Brain injury is any brain damage that impairs/interferes with the normal functioning of the brain, either temporarily or permanently.
     • Biopsychosocial changes
       • Biological changes are primarily physical. E.g. prefrontal cortex injury would affect motor activities
       • Psychological changes are primarily emotional, personality and cognition which in turn can impact on behaviour. Persistent apathy, inability to plan (severe cases)
       • Social changes are a breakdown in relationships, difficult to establish new relationships. Due to the combined biological and psychological changes.
     • Neurological disorders
       • Spatial neglect is a neurological disorder where individuals are unable to notice anything on either their left or right side. Patients believe there is nothing wrong with them
       • Parkinson’s disease is a progressive neurological disorder that has both motor and non-motor symptoms
         • Motor Symptoms: Tremors, Muscle rigidity, Slowness of movement, Postural inability
         • Non-motor symptoms: Speech, Anosmia, Slow cognitive processing, Mental Health problems
         • Treatments - Two types of dopamine-based medication to help people manage: Medication that is converted to dopamine by the brain called L-dopa. Based on levodopa which is a chemical converted to dopamine by neurons (a pre-cursor). Effectively stimulate the reception site of dopamine

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