phys: learning and memory

phys: learning and memory

1. learning

   • the process of acquiring information
   • Non-associative learning paradigms
     • learning about a single stimulus
     • sensitization (increasing response to the stimulus)
     • habituation: decreasing response to the stimulus
   • ascociative learning
     • classical conditioning:learning a relationship between two stimuli (cerebellum)
     • fear conditioning: instantaneous association between a neutral and a fearful stimulus (depends on the amygdala)
     • operant conditioning: learning a relationship between the organism's behavior (e.g. movement/act) and the consequences of that behavior
   • other forms of learning
     • imprinting: Instantaneous, non-conditional form of learning; e.g. “filial imprinting” in which a young animal (hatching birds) learns the characteristics of its parents.

2. memory

   • Motoneurone pools of each muscle form columns in the ventral horn Collections of motoneurones in the ventral horn are also called motonuclei
   • processes
     • encoding: transforming information to storaable processable form storage: holding of information retrieval: recall of stored information
     • Reconsolidation – memory traces become labile when recalled. Review/repetition reconsolidates the trace. Updating – new experience modifies earlier memory traces. Similar situations can result in recall but then consolidation of an altered memory trace. Forgetting – “fading” and removal of stored information. Lack of reconsolidation?
   • declarative memory
     • semantic
       • facts words and their meanings
       • semantic
     • episodic memory
       • events etc
       • hipocampus
     • conscious
     • formation of these memories
       • 1) Sensory Memory 2) Short-term (Working) Memory 3) Long-term Memory
         • sensory memory
           • iconic
             • visual sensory memory system. Capacity/level of detail high. Duration – approximately 1⁄2 second.
           • echoic
             • auditory sensory memory system. Duration – typically 2-3 s; but could last up to 10 seconds.
         • stm
           • approximately 7 plus or minus 2 units.
             • enhanced by chunking to approx 20-30 secs
   • procedural memory
     • knowing how i.e. playing tennis
     • unconscious
     • basal ganglia, cerebellum
   • priming
     • a earlier stimulus facilitates the recognition/identification of a second related stimulus

3. diorders

   • retrograde amnesia
     • Loss of memories (BUT the ability to learn is preserved) typical, ‘mild’ form: post-traumatic amnesia due to a head injury (concussion) no memories of the events preceding/leading to the accident sever forms: infections (e.g. encephalitis), sever head injury all past/personal memories erased
   • anterograde amnesia
     • Loss of the ability to form new memories, to learn (BUT past memories are preserved)
   • dimentia
     • Affects memory (amnesia): - progressive loss of memory - progressive loss of the ability to learn
     • Signs of AD are first noticed in the entorhinal cortex and the hippocampus. Neurons in these regions degenerate and die.
     • • In severe AD, extreme shrinkage occurs in the brain affecting the entire cortex
       • at this stage patients are completely dependant on others for care

4. neurons

   • synaptic strength
     • describes the information flow from one level to the next
       • change in synaptic srngth can serve in learning
     • ynapses become stronger between neurons if the two cells are simultaneously active.
     • long term potentiation
       • Synapses can “remember” if they receive high-frequency strong activity leading to activation of the postsynaptic neurons. A long-term increase in the synaptic responses (long-term potentiation, LTP) develops and serves as a “memory”.
       • Both phenomena depend on the simultaneous activation of two inputs. Cooperation: two weak inputs can produce LTP if activated together. Association: a weak input can produce LTP if paired with a strong one.
       • molecular mechanisms
         • AMPA receptors: - fast, reliable transmission - permeable for Na+ NMDA receptors: - transmission depends on voltage - blocked by Mg2+ at rest