Summary: Jesus gave the Nephite apostles power to confer the gift of the Holy Ghost. Between A.D. 400 and 421
“While in every instance the Nephite Twelve are spoken of as disciples, the fact remains that they had been endowed with divine authority to be special witnesses for Christ among their own people. Therefore, they were virtually apostles to the Nephite race” ( Joseph Fielding Smith, Doctrines of Salvation, 3:158; see also Mormon 9:18). (quote taken from the institute manual)
Verse three in this chapter is important; one of the reasons we have apostles is so they can not only bear witness of Christ, but remind us of what He taught us.
3 Now Christ spake these words unto them at the time of his first appearing; and the multitude heard it not, but the disciples heard it; and on as many as they laid their hands, fell the Holy Ghost.
I know that my heart is not always open to the promptings of the Spirit. I know that I miss many spiritual insights I could gain if I was a little closer to God. I am grateful we have prophets and apostles to help me remember to listen to Christ, how to listen, and often what I have missed by listening on my own.