Psych

• Hebb's theory of neural growth


  Learning and brain activation change the structure of the brain. The brain is plastic and does not have a fixed structure.
• Neuronal growth


  If a neuron repeatedly excites and is active, the synaptic terminal becomes bigger
• Neural pathway formation


  When neurons close by fire together, they form a synaptic connection with each other
• Cell assemblies


  Neurons connected through a pathway
• Processing unit


  Each cell assembly makes a single processing unit
• Learning something new


  Develops stronger cell assemblies
• Using cell assemblies more


  Improves their ability to hold on to information
• Engram


  Learning produces a small biological change
• Fight or flight response


  Normally parasympathetic branch of ANS, but threat activates sympathetic branch
• Fight or flight response

  Hypothalamus activates sympathetic branch, which transmits signal to adrenal gland to release adrenaline
• Fight or flight response


  Deals with threat and then switches back to parasympathetic
• Synaptic transmission


  Release - Electric signal and vesicles in pre-synaptic neuron release neurotransmitter in synapse

  2. Activation - If excitatory neurotransmitter binds, post-synaptic neuron more likely to fire an impulse (excitation). If inhibitory neurotransmitter binds, less likely (inhibition)

  3. Inactivation - Neurotransmitter unbinds and is reuptaken into pre-synaptic neuron
• Key structures in the brain


  • Frontal lobe - movement and thought

  Parietal lobe - sensation and body position

  Temporal lobe - understanding, hearing, memory

  Occipital lobe - visual information

  Cerebellum - movement and balance
• Localisation of function in brain


  Specific functions processed in specific parts of brain
• Examples of localised brain functions

  • Motor cortex

  Somatosensory cortex

  Visual cortex

  Auditory cortex

  Broca's region

  Wernicke's region

  Angular gyrus
• Types of neurons


  • Sensory neuron - carry info from sense organs to CNS, short axons and long dendrites

  Motor neuron - carry info from CNS to muscles, long axon and short dendrites

  Relay neuron - carry info within neurons in CNS, helps sensory and motor neurons communicate
• Brain scans


  CT Scan - Scanner takes images of brain from different angles and combines them into a 3D image. Denser areas look whiter, less dense look darker.

  PET Scan - Injects radioactive chemical into blood. Active brain areas use more blood and absorb more of the chemical, which is colour coded based on activity.
• fMRI Scans


  Measures changes in levels of oxygenated blood in active brain areas. Participants asked to do an activity, and active areas are colour coded on the brain scan display.
• Recovery from neurological damage requires creating new neural pathways
• Participants with epilepsy who had open brain surgery were conscious, and brain areas were stimulated to ask what they sensed, providing qualitative data
• A case study involved 6 participants injected with a radioactive isotope, who were then asked to think of semantic or episodic information, but 3 participants were dropped due to inconsistent results