Synaptic Plasticity and Learning Mechanisms Flashcards

This set of vocabulary flashcards covers the fundamental concepts of synaptic plasticity, behavioral learning in Aplysia, molecular signaling pathways like PKA/CREB, and hippocampal LTP/LTD mechanisms.

Synaptic Plasticity

Activity dependent changes in synaptic response or properties, thought to be the mechanism underlying learning and memory.

Synaptic Cleft

A space of approximately $20\,nm$ between the presynaptic terminal and the post-synaptic dendrite spine.

Habituation

A form of learning where a repeated light touch to the siphon results in less gill withdrawal in Aplysia.

Sensitization

A form of learning where an electric shock to the tail sensitizes the animal to a siphon touch, causing a greater gill withdrawal response.

Short-term Habituation Mechanism

A decrease in the $PSP$ of the motor neuron likely due to a pre-synaptic decrease in vesicle release from sensory neurons, with no change in sensory neuron firing.

Modulatory Interneuron

An interneuron in the Aplysia circuit that releases serotonin ($5HT$) onto the presynaptic terminal to enhance glutamate release during sensitization.

Protein Kinase A (PKA)

A kinase activated by $cAMP$ that phosphorylates potassium ($K^+$) channels, decreasing their opening to prolong the action potential and allow more $Ca^{2+}\text{ influx}$.

CREB

A transcription factor phosphorylated by PKA that binds to $CRE$, increasing the transcription of genes that promote long-term neurotransmission.

Ubiquitin Hydroxylase

A gene downstream of CREB that stimulates the degradation of the regulatory subunit of PKA, allowing the catalytic subunit to persist.

CPE Binding Protein

A self-sustaining protein that activates mRNAs to enhance local protein synthesis, allowing activity to persist even in the absence of a $5-HT$ signal.

Tri-synaptic Circuit

The anatomy of the rodent hippocampus consisting of connections between Dentate granule cells, CA3 pyramidal neurons, and CA1 pyramidal neurons.

LTP (Long-term Potentiation)

A process requiring high elevation in $Ca^{2+}$ and $NMDA$ receptor activation, leading to $CaMKII$ activation and increased $AMPA$ receptor insertion or activity.

LTD (Long-term Depression)

A process requiring lower elevation in $Ca^{2+}$ than LTP and $NMDA$ receptor activation, leading to activation of protein phosphatases like Calcineurin and decreased $AMPA$ receptors at the cell surface.