Long-term potentiation (LTP) is best described as which of the following?
AThe death of neurons following prolonged activation, clearing space for new connections
BA permanent and irreversible strengthening of all synapses throughout the brain
CThe strengthening of a synapse when pre- and postsynaptic neurons repeatedly fire together
DThe brain's ability to grow entirely new cortical lobes after injury
LTP occurs at specific synapses when repeated co-activation causes the postsynaptic neuron to insert more AMPA receptors, making future transmission easier. It is not permanent (LTD — long-term depression — can reverse it), it does not affect all synapses globally, and it does not produce new lobes. Hebb's rule summarizes the principle: neurons that fire together wire together.
Question 2 True / False
Neuroplasticity typically produces beneficial changes in the brain.
TTrue
FFalse
Answer: False
Neuroplasticity is a mechanism, not a direction. The same synaptic-strengthening processes that underlie learning also underlie maladaptive changes: chronic pain syndromes (where pain circuits are sensitized even without ongoing injury), addiction (where reward pathways are reshaped to prioritize drugs over other stimuli), and PTSD (where fear circuits become overly sensitized to trauma-associated cues). Whether plasticity is adaptive or maladaptive depends entirely on which circuits are being reinforced and in what context.
Question 3 Short Answer
A concert violinist has a dramatically expanded cortical representation of their left-hand fingers in both the motor and somatosensory cortex compared to non-musicians. What does this illustrate, and what cellular mechanism underlies it?
Think about your answer, then reveal below.
Model answer: It illustrates use-dependent cortical reorganization: cortical maps expand for body parts and movements that are used most intensively. The cellular mechanism is LTP-based synaptic strengthening — repeated co-activation of neurons in the left-hand pathways strengthens those synapses and recruits neighboring cortical territory, physically expanding the map.
Cortical representations are not fixed at birth. The motor and somatosensory homunculi are dynamic maps that reflect actual use patterns. Musicians, Braille readers, and taxi drivers all show measurable cortical map changes corresponding to their expertise. This is also why targeted rehabilitation (e.g., constraint-induced movement therapy after stroke) can partially restore function by forcing use of the affected limb and driving plasticity in the damaged region.