This week in music history is a mixed bag, featuring some high highs and low lows in rock music. Up for review are a few somber anniversaries and other anniversaries with brighter implications. Most importantly, there’s quite a bit of newness right here, fresh for the listening.

THE LAST SHOW: Brent Mydland, who was the longest running keyboardist with the Grateful Dead, played his last show on July 23, 1990.