Human fear mechanism emulator.

Mammalian fear responses depend on learning and recognizing threatening contexts. The former requires neural synaptic plasticity and long-term potentiation (LTP); the latter depends on pattern classifiers in the brain. This paper extends the author's human nervous system emulator to reproduce this fear mechanism. Beginning with brain anatomy, mechanisms of synaptic plasticity and LTP, the discussion moves to the design of this emulator, concluding with the impact of the fear response on acute and chronic anxiety, panic attacks, post-traumatic stress disorder and depression. Details include experiments by Whitlock on LTP; by Tsai on the hippocampus Cdk5 signaling pathway; on NMDA-dependent recognizers by Nakazawa and McHugh; by Tsien on a NMDA-mediated hippocampus neural memory code; by Bolshakov on amygdalanorepinephrine (NE) emotional response tags; and by Hurlemann on drug effects on NE-mediated emotional responses.