Figure 4. Schematic drawing of a CA3 pyramidal neuron plus its dendrites. Note the small soma in comparison to the highly arborized apical and basal dendrites. Inset; dendritic shafts can build up protrusions (spines) that form synapses with axons or dendrites from other neurons. Synapses are sites of signal transmission between neurons. Formation and disappearance of spines are regulated by many factors such as gonadal hormones. Chronic psychosocial stress reduces the arborization of the apical dendrites, thus reducing the surface area of the neuron with the consequence that the neuron receives less information from other neurons (see text for details).