What does the word trends mean within the context of paragraph 9, and what does the study of trends have to do with the time-consuming nature of brain research?

Baca use comforting imagery. which lines have a more serious tone than the rest of the poem a. when the outside world / no longer cares if you live or die; b. so it is a pot full of yellow corn / to warm your belly in winter, c. remember. / i love you.d. it's all i have to give, / and all anyone needs to live,