This can involve either synergistic positive induction of {HEAD ~ neuronal cells} by {TAIL ~ N}, or negative modulation by delta N—C for example  
by
This can involve either synergistic positive induction of { HEAD ~ neuronal cells } by { TAIL ~ N } , or negative modulation by delta N — C for example
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH