3.3-3.4

• Memory

  Memories include past experiences, knowledge and thoughts. Memory involves encoding, storage and retrieval of information.
• Memory

  Information enters sensory memory, then short-term memory, then transferred to long-term memory or displaced/decayed
• Encoding

  Transferring information into memory
• Storage

  Retention of information over a period of time
• Retrieval

  recalling information stored in short-term or long-term memory
• Sensory memory


  • Retains all visual and auditory input received for a few seconds. Only selected images and sounds are encoded into short-term memory.
• Short-term memory (STM)


  • Limited capacity - only 7 items of visual or auditory images are retained before being lost by displacement or decay. Can process data and store it.
• Chunking


  Breaking down large pieces of information into smaller chunks to increase memory span
• Rehearsal


  Repeating information to yourself to extend the time it is retained in STM and prevent displacement and decay
• Long-term memory (LTM)


  Has unlimited capacity and holds information for a long time. Transfer of information from STM to LTM is promoted by rehearsal, organisation and elaboration.
• Rehearsal


  A shallow form of encoding information into LTM, involves repeating information again and again
• Organisation


  Organising information into categories
• Elaboration


  A deeper form of encoding which leads to improved information retention, involves adding additional/meaningful information
• Retrieval


  Recall of items from long-term memory when required, aided by contextual cues
• Contextual cues


  Relate to the time and place when information was initially encoded into the memory
• Methods of transferring information from STM to LTM

  • Rehearsal
  • Organisation
  • Elaboration
• Rehearsal is a shallow form of encoding, while elaboration is a deeper form of encoding
• Sensory memory


  Environmental stimuli perceived as sensory images, enter sensory memory and are quickly lost unless selected and encoded into short-term memory
• Short-term memory


  Selected images and sounds are encoded, has limited capacity, can process and store data, memory span can be improved by chunking and rehearsal
• Long-term memory


  Information transferred from short-term memory, has unlimited capacity, information retained through rehearsal, organisation and elaboration, information retrieved with aid of contextual cues
• Neurons are nerve cells that receive and transmit electrical signals (nerve impulses)
• Types of neurons


  • Sensory neuron, motor neuron, interneuron
• Structure of neurons


  • Dendrites, cell body, axon surrounded by myelin sheath
• Dendrites


  Nerve fibres that receive impulses and pass them towards the cell body
• Axons


  Fibres that conduct impulses away from the cell body
• Myelin sheath


  Insulates the axon and increases the speed of impulse conduction. Myelination continues from birth to adolescence.
• Responses to stimuli in the first two years of life are not as rapid or coordinated as those of an older child or adult due to less myelination
• Glial cells


  Produce the myelin sheath and provide physical support to neurons
• Synapse

  • Neurons connect with other neurons or muscle fibres at a synaptic cleft. The neuron before the cleft is the presynaptic neuron, the one after is the postsynaptic neuron.
• Neurotransmitters


  Chemicals that relay impulses across the synaptic cleft from neuron to neuron
• Neurotransmitters

  • Acetylcholine, noradrenaline
• Neurotransmitter release


  Stored in vesicles in the axon ending of the presynaptic neuron, released into the synaptic cleft when a nerve impulse reaches it, diffuses across the cleft and binds to receptors on the postsynaptic neuron
• Neurotransmitter removal


  Broken down by enzymes or re-uptake by the presynaptic neuron, energy provided by mitochondria in the presynaptic neuron
• The type of receptor involved determines whether a signal is excitatory or inhibitory, the signal passes on if the strength of the excitatory signal exceeds the inhibitory ones
• Synapses can filter out weak stimuli arising from insufficient secretion of neurotransmitters
• Enzymes

  Some neurotransmitters such as acetylcholine are broken down by enzyme degradation
• Re-uptake of neurotransmitters

  By the pre-synaptic neuron
• Energy (ATP)


  Provided by mitochondria which are abundant in the pre-synaptic neuron
• Receptors


  On the postsynaptic neuron determine whether the signal is excitatory or inhibitory
• Neurotransmitters bind with receptors