MSN: 'What Sex Does to a Man's Brain'

Article here. Excerpt:

'She appears at the curb, waiting to cross. No, she's not the love of your life. She's more like the heat of the moment. It's fortunate that your wife isn't there, otherwise you'd be in deep trouble as you take in the stranger's hips and breasts, and the way her waist scoops in to accentuate both. Time is enhanced; there's a pleasing buzz connecting your temples.

Your reaction is automatic, reflexive, and quite possibly the most powerful one you'll have this day. It temporarily blots out your long-range commitments — that 10-year marriage, that kid in second grade, that responsibility to keep eyes forward at traffic lights. You've surrendered control; you're captivated by the pleasure in the vision.

"You dog!" you may whisper under your breath, embarrassed by what you're envisioning as you sit there in your family van. But it might be more correct to say, "You dopamine fiend!" As a neuroscientist of 25 years, I know that your brain is command central for everything sexual.
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Why You've Always Been Horny

You've been lit up on testosterone right from the start, even when you were just a multicelled notion in your mother's womb. The inherited Y chromosome that makes you male (thanks, Dad) triggers two bursts of testosterone that change your brain and body.

The first produces a male brain: one that's more interested in objects, actions, and competition. The left (parietal) lobe flourishes in the testosterone bath and helps you visualize objects in three dimensions (good for catching a football or watching a woman cross the street), and it boosts your aptitude in mathematics (that's how you estimate that she's about a 34DD). In addition, testosterone beefs up your hypothalamus, the area of the brain that's interested in sex. The hypothalamus is twice as large in men as it is in women.'