MAOB ( = degrading enzyme of trace amines)
    1 .  Striatal PEA increase in MAOB knockout mice [37].
    2 .  Therapeutic usage of MAOB inhibitor for hypersomnia.
         (Due to PEA increase?)    
 Neural stem cell (NSC)
    1.   NSC dysfunction hypothesis of schizophrenia.
    2.   Findings of ventricular enlargement in brain imaging
         of schizophrenics.
    3.   D-neuron decrease in striatum and nucleus accumbens of patients
         with schizophrenia.
Trace amine (TA)
    1.   Disturbance of sleep-wake-rhythm of patients with
         schizophrenia. (insomnia and daytime hypersomnia)
    2.   Decrease of putative trace amine-producing neurons
         (=D-neurons) in post-mortem brains of schizophrenics.
    3.   Decreased anxiety-related behaviors in PEA-elevated
         MAOB knockout mice [38].
     4.  “Phenylalanine hypothesis of affective behavior”
            by Sabelli & Mosnaim (1974) [39]
 NSC suppression via DA D2 receptors on NSC
         Preventive effects of chronic administration of
         D2 blocking agents for recurrent psychoses.
Table 1: Some clinical and /or experimental evidences supporting D-neuron-trace amine hypothesis (D-cell hypothesis).