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106 CHARACTERISTICS OF BRAIN AND BEHAVIORogy including the hippocampus, subdivisions of the prefrontal cortex, the thalamus,and the striatum. Most likely, it is the disrupted communication between theseregions that leads to the manifestation of schizophrenic symptoms. Although subtlestructural and anatomical irregularities within these regions have been reported,there is no gross anatomical abnormality or specific neurochemical deficit thatuniquely identifies schizophrenia. More likely, molecular alterations within theseFigure 5-2 Generalized depiction of transcriptional and translational processing in nervecells. For purposes of simplicity, the nucleus appears in white and the cytoplasm is gray.1. DNA is transcribed into RNA. The premature RNA contains both introns (green)and exons (red). Introns are sections of the RNA that do not encode protein, whereasexons are sections of the RNA that encode protein.2. The RNA is capped at the 5´ end and polyadenylated on the 3´ end—the first twomajor steps of mRNA processing. These additions protect the RNA from degradationand assist in trafficking the RNA to the cytoplasm.3. Splicing of the primary mRNA that removes introns (noncoding regions of mRNA),resulting in messenger RNA (mRNA), is the third major step of mRNA processing.4. mRNA is exported from the nucleus to the cytoplasm.5. mRNA (red strand) is translated into protein by ribosomes (oblong purple objects)located in the cytoplasm. The black circles represent the nascent protein as it is translatedby the ribosomes.