HTR1A and Anxiety: The SPS-induced increase of 5-HT1A receptors in neurons of the oculomotor nucleus may reduce the 5-HT neurotransmitter released from the oculomotor nucleus to control the eye muscle nerve fibers but may increase norepinephrine release, which leads to increased alertness, anxiety, and startle reactions accompanied by the symptoms of abnormal eye movement in PTSD patients.