Table 1.

Changes in synaptic number in the morphine treated group.

Groups	Synaptic density per 1 × μm3	95% confidence interval	P value
Morphine	1.85	2.0930–1.6069	P < 0.0001
Placebo (sucrose)	0.8	0.9293–0.6706
Control	0.67	0.8209–0.5910