The Portland Symphony Orchestra’s celebration of spring, when in the words of Tennyson — “A young man’s fancy lightly turns to thoughts of love” — includes two of the most erotic works in the repertoire, Ravel’s “Daphnis and Chloe” and the “Liebestod” from Wagner’s “Tristan und Isolde.”

Perhaps it’s synchronicity that it was reported in “Discover” this week that scientists at the Montreal Neurological Institute have discovered that music activates the same reward centers of the brain as food and sex.

Some pieces of music activate better than others, but the effect has nothing to do with content. Overt or hidden erotic messages, as in the pieces programmed by the PSO, may help, but Beethoven and Bach affect the same pleasure centers as “Der Rosenkavalier.” What other areas they stimulate — memory, discovery, aesthetic beauty or rational intellect — is an entirely different question. (See Oliver Sacks’ “Your Brain on Music.”)

Apparently, PSO music director Robert Moody has selected the two leading candidates for the most erotic piece of music, at least according to an informal survey conducted at talkclassical.com. Bach is in there too, with “Wann kommst du, mein Heil?” from the Cantata No. 140.

What about the third work on the program, the Mozart Bassoon Concerto, written when he was 18? The second movement became the Countess’ aria from the second act of “Le Nozze di Figaro,” an opera with the largest number of selections in the 2003 recording, “Making Out to Mozart.”

Richard Strauss has the largest number of mentions, including “Der Rosenkavalier,” which is full of hidden risque meanings, “Salome” and even the “Domestic Symphony” and the “Four Last Songs.” Strangely enough, no one mentioned “Die Frau Ohne Schatten,” which is about nothing but eroticism.

Another Ravel work, the “Bolero,” also had several mentions. I find it quite similar to the “Liebestod” in its gradual build-up to an overwhelming climax, in the case of the Wagner a union of Eros and Thanatos, and in the Ravel, appropriately enough, a change of key.

Among the moderns are, of course, Stravinsky’s “Rite of Spring” and Schoenberg’s “Pierrot Lunaire,” plus John Adams’ “Harmonium.” Given that Adams is one of Moody’s favorite composers, it would be interesting to hear this in spring 2012.

There was also considerable discussion of Luciano Berio’s tape “Visage” for voice and electronic sounds, although to my mind, this one and Pierrot seem more weird than erotic.

One work that I was not familiar with was Karol Szymanovski’s Symphony No. 3.

Szymanowski, a friend of pianist Artur Rubinstein, was openly homosexual when that was taboo, and the symphony is supposedly full of homoerotic messages.

I have always wondered exactly how erotic images could be conveyed in music, but an analysis of the images in the Third Symphony told me much more than I wanted to know. The treatise is one of the most abstruse pieces of musical analysis I have ever encountered, having to do (I think) with chordal analysis and progressions, as well as rhythm.

On the subject of eroticism in music, one has to fall back on the old dictum about pornography: “I know it when I see it.”

In the meantime, “If music be the food of love, play on.”

Christopher Hyde is a writer and musician who lives in Pownal. He can be reached at classbeat@netscape.net