What is the author's style in Animal Stories by Jason Brown?

Brown freely switches back and forth between different years in the story, even within the same section. For example, one section begins with Jamie referring to the summer of 1977, when "we stayed inside and drew the shades." A few paragraphs later, but still in the same section, he is back in the recent past, and his mother's doctor is demanding that she either accept the biopsy procedure or leave the hospital. While Jamie speaks of his mother's stay at the hospital using the present tense, a few paragraphs into the story he makes it clear that this episode is in the past; he notes, "By the time this happens"—that is, finding out about his mother's brain tumor—"it is too late for me." As well, he closes the story by stating, "This is my entire life, everything that I remember."