Final answer:
Long-term potentiation (LTP) enhances synaptic strength, leading to improved memory and cognitive control, while long-term depression (LTD) weakens synaptic connections, enabling the forgetting of less crucial information.
Step-by-step explanation:
Long-term potentiation (LTP) and long-term depression (LTD) are processes that represent the synaptic mechanisms underlying learning and memory. LTP is characterized by a persistent strengthening of synaptic connections, which is based on the Hebbian principle that 'cells that fire together wire together'. This synaptic strengthening occurs through a sequence of events: 1) The depolarization of the post-synaptic neuron, often due to repetitive, high-frequency stimulation, dislodges magnesium ions blocking NMDA receptors. 2) This allows Ca²+ ions to enter the cell, triggering a signaling cascade. 3) This cascade leads to the insertion of AMPA receptors into the postsynaptic membrane. Consequently, when glutamate is released again, the post-synaptic neuron is more likely to fire due to enhanced receptor activation.
Conversely, LTD is the process of long-term weakening of synaptic connections. It is equally important for learning as it allows for the 'pruning' of less active synapses, enhancing the contrast and strength of more frequently used pathways. Calcium entry through NMDA receptors during LTD activates a signaling cascade that ultimately results in the removal of AMPA receptors from the post-synaptic membrane, thus making the neuron less responsive to glutamate.
The influences of LTP in an individual like Lea could manifest in enhanced cognitive control, improved memory, and potentially a predisposition to addiction if drugs co-opt these synaptic pathways. LTD, in contrast, may aid in forgetting unimportant information, ensuring essential information is retained more efficiently.