Physiological Psychology
Molecular bases of learning and memory.
Conclusions
1. Learning is the results of the multiple neural processes by which experience changes
our nervous system and, consequently, our behavior
2. The morphology of neurons is constantly changing along life.
3. The activity of neurons, be it the result of formal training or of informal experience,
a) produces chemical and electrophysiological in the brain,
b) and promotes structural changes (new synapses, new dendritic branches and new
dendritic spines)
4. Formal training and informal experience:
4..a Correlate with increases in the expression of different genes.
4..b Promote the survival of new neurons in the hippocampus
4..b..i The rats housed in rich environments have more neurogenesis
4..b..ii The new neurons are incorporated into local circuits
4..b..iii The survival of new neurons is associated to learning processes
dependent on the hippocampus, for instance, trace classical
conditioning and spatial cognition
5. Invertebrates, in particular Aplysia californica and Drosophila melanogaster, provide
very useful models to analyze the neural bases of learning processes because they have
a small number of neurons and many are large and easily identifiable
6. Aplysia has provided essential information about the cellular mechanisms of
habituation, sensitization and classical conditioning.
6..a Short-term habituation and sensitization of the gill-withdrawal reflex
imply a decrease, or an increase, respectively, in the amount of neurotransmitter
released by the sensory neuron in the synaptic cleft.
6..b Aplisya can also be classically conditioned. Classical conditioning-
dependent plasticity take place in the synaptic terminal of the sensory neuron
6..c At the molecular level, the EC is represented by the influx of Ca++, and
the EI by the G-protein-coupled activation of the adenylil cyclase in the axon
terminal.
6..d In the presence of Ca++ adenylil cyclase determines the synthesis of
high amounts of cyclic AMP.
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