The first category, perception, deals primarily with the five senses. One of the most interesting studies showed pregnant women had sharper "visual acuity" than women who weren't expecting. By that I don't mean they suddenly had 20/20 vision but they did notice a lot more. Studies show that pregnant women also have an enhanced sense of smell, which theoretically serves to protect the unborn baby from foods that are potentially harmful.

Other findings show that mothers can experience a boost in motivation, fearlessness, and the ability to multitask and cope with stress. There's also exciting new research suggesting that oxytocin -- a hormone important to labor and breastfeeding -- improves moms' capacity for learning and memory.

Emotional intelligence is probably the clearest category in which mothers benefit, though. One of the biggest brain boosts for moms is the ability to see the world through someone else's eyes. In so many relationships, if you don't agree with a person you can just walk away. But you can't walk away from your child. At least, not if you want to be a good parent. Instead, you've got to stretch your mind to understand his point of view.

Did you find that people expected you to be "less smart" after you had children?

Yes. For instance I'd be sitting around with a group of women and someone would say something silly and then laugh it off as "mommy brain." Those kinds of experiences, trivial as they may seem, can make you feel as though you're going to accomplish less in life as a mother than you otherwise might as a childless woman.

Perhaps more important, I got a new editor after my second son was born who let me know that he thought I was going to be less productive and that I wouldn't be able to keep my mind in two places at once. He was wrong, of course, but his distrust shook my confidence for a while.

In what ways did motherhood make you smarter?
I found motherhood tremendously stimulating, like getting a crash course in human nature. I also got much better at time management. Because I'd been a newspaper reporter, I thought I was good with deadlines. But when I had a baby, the deadlines got a lot less flexible. I was forced to manage my days in a whole new way.

As a mother, the notion of having less time to waste informs your whole life. I became smarter about networking with other women, handling chaos, and dealing with difficult people. I know if I returned to the daily newsroom today, I'd be more savvy in dealing with editors having temper tantrums! Apparently former Secretary of State Madeleine Albright shares my viewpoint. When asked which part of parenting helped most in her subsequent diplomatic career, she answered, "Getting people to play well together!"

More generally, motherhood helped me focus on the future. I became determined to prioritize things, like environmental issues, that will matter more in my children's life than my own. At the same time, I found the motivation to accomplish other ambitions I'd had for many years. For instance, I'd always wanted to have a close-knit group of friends, more creativity in my work, and a lifestyle that would give me the leeway to write longer articles and books. All those things came true after I had children. It wasn't simply the act of being a mother, it was thinking about what I wanted to accomplish for myself and for my kids.

Several women in the book talk about making the same type of change. It's sort of like a midlife crisis. Once you have children, you reorganize your priorities. You think about your legacy and take your life more seriously when you realize your children will examine it later.

What was the most surprising thing you learned while researching the book?

My research was full of surprises. One thing that jumps to mind is a series of studies done by scientists in Switzerland, who compared the brain scans of parents to those of childless people. They found parents' brains were more active when listening to a baby's cry. On the flip side, brains of people who didn't have children were more active when they heard a baby's laugh.

This suggests that a rewiring of the human brain occurs once you have children. Some researchers see it as evidence that motherhood makes women more empathetic. One scientist I interviewed says that moms learn empathy skills with their babies that they can later take out into the world at large.

Another surprising study showed that mothers react even to the annoying sound of a baby's cry with parts of the brain that are activated during pleasurable activities like eating a good meal or winning money. By equating the nurturing of a child with great food or sex, nature is ensuring that you'll bond with your baby, and stay engaged with the mental challenges your child will present you with for years to come. It's a pretty great system!

How does "daddy brain" change after the baby arrives?

Some interesting recent studies show that new fathers mimic in many ways the hormonal changes their wives go through, although on a much lower level. For instance, expectant fathers experience a surge of prolactin, a hormone typically associated with nurturing and breastfeeding, as well as increased levels of estrogen, the "female" hormone. Experts aren't sure why men experience these changes, but they think the higher hormone levels may help dads bond with their offspring. And the changes aren't all chemical. I interviewed many fathers who told me they had become more patient and empathetic after spending a lot of time taking care of their kids.

How do mothers make each other smarter?

As a mother, you learn to strategize. When you see mothers exchanging information on the playground, for instance, it may look casual -- but they're often earnestly collecting information that will ensure the well-being of their offspring, such as the name of the best teacher at the local school and whether strep throat is going around. Swapping this kind of information isn't rocket science, but it's important in an evolutionary sense.

Are the mind-boosting benefits of motherhood temporary or permanent?

That's hard to measure with humans, but in rat studies the benefits of mothering last until the animals reach an age equivalent to age 80 in humans, which I find very encouraging. And, when it comes to people, we know that seniors who are more connected to the outside world, especially through their children and grandchildren, are often healthier -- mentally and physically -- than those who are isolated. So motherhood continues to pay off late in life.

Why do you say mothers today need to be smarter than ever?

The mental demands on mothers are greater than ever. To do a good job of helping our children thrive, mothers today have to be information analysts. We're constantly bombarded with information from television, parenting books, and talk shows Ã??? not to mention, constant news reports about increasing rates of childhood asthma, autism, and ADHD. We have reason to worry and be up-to-date on everything from mercury in tuna to arsenic in playground equipment.

At the same time, to truly protect our kids, moms must often confront a culture that in many ways is harmful to children. Advertisers now spend fortunes marketing directly to kids Ã??? encouraging rampant consumerism and unhealthy diets. A surprising number of moms step up to the plate and become more assertive.

What advice do you have for new mothers?

Just appreciate how much you're learning and how much your brain is being challenged and enriched by your baby instead of turned to mush. You may feel exhausted, but if you pay attention to how much you're learning in an incredibly short time, the sheer enormity of it is energizing.

Oh, and don't underestimate the importance of sleep! If you and your partner share the responsibility of getting up at night with your baby, it'll make both of you better parents in the long run.

The Seven: How to make the most of your mommy brain

Take Back Motherhood: If you lost interest in world affairs when your baby was born, don't fret. Your brain hasn't shrunk -- it's just otherwise occupied. New moms become super-attentive learning machines, says Ellison. Your baby is challenging your brain on every level, every minute of the day. You probably haven't absorbed so much new information this quickly since you were a baby yourself, so give credit where credit is due.

Sleep: Sleep deprivation is inevitable, but no one should shoulder the burden single-handedly. In the first year of your baby's life, his primary caregiver stands to lose 700 hours of sleep. Numerous studies have shown that lack of sleep can mess with brain function. In fact the brain's frontal cortex, responsible for keeping you alert, innovative, and flexible, is the first to falter during extended sleep loss. So don't surrender your Z's without question. Instead, sit down with your partner and make a sleep plan. Then stick to it. For each of you to stay as rested as possible, Ellison suggests trading off in three-night shifts. If you're breastfeeding, have your partner bring the baby to you, and pump milk ahead of time so he can bottle-feed the baby when it's your night off.

Breastfeed: Oxytocin, a hormone released during childbirth and breastfeeding, promotes feelings of calm and cements the mother-child bond. And recent research suggests that this natural mellowing agent may boost your capacity for learning and memory. For a continuous supply of this hormone breastfeed your baby. Experiments show that nursing moms feel more relaxed physically and emotionally and are more sociable than mothers who don't breastfeed.

Get social: Don't let motherhood turn you into a lactating hermit. Being a new mother means you're vulnerable in a whole new way and need people in a deeper sense than you ever have before, says Ellison. Seek out other mothers at the playground, the gym, even the grocery store. Other mothers empathize with what you're going through like no one else. One large study funded by the National Institutes of Health found that belonging to a B social network correlates with better mental functioning. Plus, social support helps ward off postpartum depression -- a problem that affects 10 percent of new moms.

Don't be a couch potato: Having a baby doesn't mean you should trade your gym membership for Tivo. Unlike watching TV, exercise makes more blood flow to the brain and fights off the blues. Make exercise a priority rather than a luxury. Create a pact with your partner to support each other's exercise habits by babysitting while the other goes for a walk or to a yoga class.

Eat your veggies: Your mother was pretty smart to give you this advice. Studies have found that antioxidants in fruits and vegetables can help prevent declines in brain function due to aging, and leafy green and cruciferous vegetables (including broccoli, cauliflower, romaine lettuce, and spinach) are particularly helpful for older women's memories.

Don't neglect the other parts of your brain: Even though your brain is tuned to the mommy channel most of the day, don't forget you also have a "me brain," a "friend brain," and a "spouse brain." Take time to stay connected to yourself and the people who loved you before you became a mother. If you can afford a babysitter, don't feel guilty about spending an hour at a coffee shop staring out the window instead of running errands at full speed or working. If a babysitter is out of the question, use nap time to squeeze in a phone call to a friend and give yourself five minutes to talk about children. Then deem kid-talk off-limits so you both can connect on a different level. The same goes for your spouse. When you finally eke out a few minutes alone, whether at night or (lucky you) on a date, allow yourselves 15 minutes to chat about kid stuff, then make the topic taboo so you can remember what it was that made you decide to have a child together in the first place.

Top tips for dads on bonding with your baby

One of my clearest memories of early motherhood involves early fatherhood. I never would have expected my husband -- a champion coach in the delivery room -- to be so indifferent to the trophy we were taking home. Sure, he loved our son, but he insisted it wasn't the same for him as it was for me. I got to feed Kyle, spend the day with Kyle, rock him to sleep; my connection to our new son was so profound that he might as well have still been linked by an umbilical cord. On the other hand, my husband would come home from work and seem completely baffled by the baby.

Well, Tim found out quickly what most moms know from the very start: namely, that a baby's got charm and grace galore. I'd hand him Kyle to watch for a moment, and come back to find the two of them grinning like fools on the couch.

Now, after having three children, I realize my husband was just shy. Taking care of a newborn is often elementally reduced to feeding and comforting, and some new dads don't know if they've got the right equipment for the job. The real secret of male-bonding with a baby is realizing that you're not supposed to try to be another mother. Your child already has one of those, and what she really needs is for you to be yourself. Still feeling a little shy? Try these break-the-ice activities.

Give a midnight bottle

After I began to supplement breastfeeding with formula, my husband offered to get up for the middle-of-the-night banquet. Okay, so maybe I bullied him into it at first, but before long he told me he enjoyed having that time with the baby. No one else around, crickets chirping outside, and bizarre infomercials on TV. Once, I overheard my husband having a 3 a.m. conversation with a sound-asleep Kyle. "You know what, buddy?" he was saying. "We're the only two people in the universe who know that they aired that same show about Wilt Chamberlain four nights in a row."

Have a staring contest

Prowess is a guy thing, right? Lest you believe that little baby of yours is a pushover, engage her in a time-honored ritual of seeing who'll blink first. She may surprise you. Babies love to contemplate faces, and chances are that before she gets bored you'll have dropped your gaze, wondering where she got that incredible dimple, or whether her ears look like your mom's or your wife's.

Play kangaroo

My firstborn was a colicky baby who was never happy unless someone was holding him. At the end of the day, Tim used to come to the rescue by strapping on a Snugli and going about his business -- raking leaves, setting the table, tossing a ball for the dog -- all with Kyle cuddled against his belly.

Take a bath together

A new dad we know dreaded the nights when it was his turn to bathe his son -- the combination of screaming baby and slippery skin made him nervous. One night, he simply stripped down himself and took the infant into the tub with him. Lo and behold, the baby was calm for the entire duration of the bath. Being snuggled against his father's chest made all the difference.

Read the sports page

Aloud. Let's face it: Goodnight Moon can get you only so far. After the 1,500th reading of the classic book, my husband finally threw in the towel. I walked by the nursery at bedtime to hear him very sweetly crooning the details of a Patriots game to Kyle. The baby loved every minute of it ... it didn't matter what his father was reading, just so long as he was.

Set a table for two

If your baby is old enough to be eating solid food, then you might as well be the maitre d'. It's entertaining -- see the food go in, watch it come right back out!

Change a diaper

Talk about bonding at the earthiest level -- with babies, the bottom line (no pun intended) often involves cleaning up a mess. During a change you get to touch the baby, and talk to him, but it's sometimes hard to see a silver lining when a soggy lining is so much more evident. Still, fair's fair. My friend Mary's husband once asked her what she did all day with the baby, so she lined up 18 dirty diapers in neat, plastic piles on the front stoop for him to see when he came home.

Be there for a cold or fever

Nobody wants their baby to get sick, but there's nothing like an illness to prove how much the little guy really needs you. A night spent rocking a sick child will make you painfully, preciously aware of what parenting is all about.

Bench press

The bad news is that once you're a parent, you don't have much time to get to the gym. The good news is that you have just acquired a fabulous set of hand weights, approximately 7 to 20 pounds. Once our kids' necks could support the weight of their heads, Tim would balance their bodies on his palms and then carefully curl them, bench them, whatever struck his fancy ... and both his biceps and the babies loved it.

Be a texture board

One of the greatest attributes of men is that they feel great (or they probably wouldn't be daddies in the first place). From the rough shadow of beard to a silky moustache to a crewcut hairdo, a father is a tactile delight. Beware: Little fingers can get a punishing grip on chest hair.

Roughhouse (within reason)

Studies have shown that mothers and fathers hold their babies in very different ways. Moms are more likely to cuddle; dads tend to get a little more physical. You should never shake a baby, but you can certainly stimulate her muscles. If your child is old enough to sit up, she might like being tossed gently in the air, or getting bounced on a knee, or being carried beneath the arm like a football ... things that Mom isn't as likely to do, but that are sure to bring squeals of delight.