Dendritic Spine Density

Local Brain Estrogen Synthesis

The brain makes its own estradiol from testosterone, in neurons and astrocytes, independently of what the testes supply. This single fact is why a blood estradiol reading does not tell you what the brain has, and why an aromatase inhibitor is a different kind of intervention from simply having low testosterone.

NMDA Glutamate Receptor

The receptor that carries the calcium current behind learning. It is also the route by which too much glutamate kills the cell, so the same channel that writes memory is the one that destroys the neuron when it stays open too long.

Synaptic Plasticity

The brain's ability to strengthen and rebuild connections. It is what learning physically is, and it is the endpoint almost every nootropic peptide claims.

Working Memory

Holding and manipulating information over seconds. The cognitive measure most sensitive to lost sleep and to raised cortisol, which makes it the one most likely to move on these compounds and the one least likely to be noticed as a cognitive effect.