Gnawing your way through the latest Mars Volta record is always something of a chore at first. The band, anchored by instrumentalist/composer Omar Rodriguez-Lopez and lyricist/vocalist Cedric Bixler-Zavala, turns out huge mind-fucks as songs, mixing prog-metal, psychedelia, and swaggering Latin flavors into massive, album-long narratives whose intent is to confound. The reward comes after you've digested the concept and you can focus on the ephemera. 2003's De-Loused in the Comatorium was a sci-fi tale about a protagonist named Cerpin Taxt, whose botched suicide attempt lands him in a coma wherein he has fantastic adventures, until reawakening and finally finishing the job. Frances the Mute, the band's 2005 LP, was on sturdier ground but no less of an aural adventure, telling the story of a man named Cygnus searching for the biological mother (Frances) who abandoned him, and encountering religious oppression, addiction, and trauma along the way. Amputechture marks a serious turning point for The Mars Volta; it's the first record without a single narrative running through it. Bixler-Zavala has claimed inspiration from such disparate sources as the pro-immigration marches and news pieces about possessed nuns, and if you really want to delve into his lyrical symbolism, you can scope out what the Volt-heads at www.thecomatorium.com have spent countless hours interpreting. The important thing to know about Amputechture is that it's pretty much exactly what you'd expect from The Mars Volta even more technically acute than the band's previous efforts, with sprawling tracks like the near-17-minute-long "Tetragrammaton" (the album's highlight), and as much ear-twisting psychedelic rock as you can take in a single sitting. It pulses with anxiety, frustration, yearning, and the burden of over-intelligence, but that's why we buy The Mars Volta records to feel alive.