The Autistic Brain: Thinking Across the Spectrum (36 page)

Dr. Panksepp also writes about three other positive emotion systems researchers don’t know as much about, and that don’t necessarily run through an animal’s entire life. He calls these three emotions “more sophisticated special-purpose socioemotional systems that are engaged at appropriate times in the lives of all mammals.”

LUST:
LUST means sex and sexual desire.

CARE:
CARE is Dr. Panksepp’s term for maternal love and caretaking.
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PLAY:
PLAY is the brain system that produces the kind of roughhousing play all young animals and humans do at the same stage in their development. The parts of the brain that motivate PLAY are in the subcortex.
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No one understands the nature of playing or the PLAY system in the brain well yet, although we do know that play behavior is probably a sign of good welfare, because an animal that’s depressed, frightened, or angry doesn’t play. The PLAY system produces feelings of joy.

Taken together, these seven emotions—especially the first four—explain why some environments are good for animals (and people) and others are bad. In a good environment you have healthy brain development and few behavior issues.

Pigs in Disneyland

The Brambell Report said animals should be free to express normal behaviors, but it didn’t say animals have to have natural environments. For as long as I’ve been working in the field of animal behavior and welfare, “enriched environments” have been the main approach to giving animals a good emotional life.

The idea that animals are happier in enriched environments first came from research psychologists working with lab rats. In the 1940s, Donald Hebb, a Canadian psychologist, raised some young rats in his house instead of in a laboratory cage. Later on, when he tested them, they had higher intelligence and better problem-solving abilities than the rats that grew up in cages.

Twenty years later, in the 1960s, a research psychologist named Mark Rosenzweig was the second major researcher to study lab rats in enriched environments.
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No one in the general public has ever heard of him even though he showed that an adult brain could grow new cells, a finding that went totally against everything neuroscientists believed. Dr. Rosenzweig’s enriched adult rats had an 8 percent increase in thickness of the cerebral cortex.
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That was an amazing finding, but nobody picked up on the idea that the brain could be plastic (could grow and change) in adult rats as well as juveniles.

Bill Greenough’s experiments in the late 1960s and 1970s raising baby rats in stimulating environments were the studies that became famous. Bill raised one group of rats in a standard plastic laboratory cage with shavings on the floor. The other group lived in an enriched environment filled with lots of toys and old wood boards. He brought in new toys every day and changed the position of the boards, so the enriched environment also included a lot of novelty and change. When he looked at the brains, he found that the rats in the enriched environment had greater dendritic growth in their visual cortex.
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Dendrites are tiny little threads that branch out from brain cells and conduct electrical impulses into the cell body. Rats living in stimulating environments had more brain growth.

Bill’s work had a huge effect on me, and I think he influenced the whole field of animal welfare, because researchers have been studying barren and enriched environments for thirty years now. I went to the University of Illinois in 1981 to work with Bill because of that study.

When I sent in my application, I was especially concerned about the way farms were treating their pigs. There was a lot of controversy, which is still going on today, about the sow stalls where mama pigs were kept locked up for their whole pregnancy. The sow stalls were so narrow the pigs didn’t even have enough room to turn around. I thought that maybe if I duplicated Bill’s rat research in pigs I would have a biological test researchers could use to prove that barren environments are bad for pigs. I would be able to show that pigs raised on hard plastic floors they couldn’t root in had fewer dendrites than pigs raised in nice straw-bedded pens.

So, for my dissertation research, I copied Bill’s enriched rats experiment using young pigs. Twelve of my piglets lived in six baby pens with perforated plastic floors and nothing much to do. The other twelve lived in a Disneyland for pigs with lots of straw to root in and toys to play with: plastic balls, old telephone books they could rip up, boards, and a metal pipe they could roll around the floor. Every day I was putting new things in and taking old things out. New things were the key. The pigs loved fresh, new straw, which they found very interesting. The old straw was boring. You would think straw is straw, but it isn’t. New straw was exciting; old straw wasn’t.

My hypothesis was that the brains of the Disneyland pigs would show more dendritic growth than the brains of the barren-environment pigs. Back then the only way to compare neurons from one brain to another was to spend hours and hours staring into a microscope and drawing the cells by hand, which I did. I looked at two parts of the pigs’ cortex: the visual cortex, which was where Bill’s enriched rats had extra dendritic growth, and the somatosensory cortex, which receives information from the pig’s snout.

When I finally got done, I realized the Disneyland pigs didn’t have any greater dendritic growth at all. I was even more surprised to find out that my barren-environment pigs did have greater growth. Also, my barren-environment pigs had their extra growth in the somatosensory cortex, not the visual cortex where Bill’s rats had shown extra growth.
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My experiment totally contradicted Bill’s. My enriched pigs didn’t have greater brain growth, and the part of the brain where my underestimated pigs did have greater growth was different from the part where Bill’s enriched rats had theirs.

When I told Bill about my results he said, “Oh, s***.”

He thought I must have made a mistake, so I had to do the whole experiment over again. This time I installed a battery of security cameras trained on the pigs so I could see what they were doing when I wasn’t around.

I already knew my barren-environment pigs had to be different from my Disneyland pigs, because they were so hyper. I’d go to clean the pens and they’d bite the hose over and over again and get in the way; they wouldn’t stay away from me. That was from the environmental deprivation, which makes animals hyperactive. When the pigs saw the water hose, their SEEKING system went into overdrive.

I found out from watching the videotapes that they were hyper at night, too. All night long they were rubbing their noses into each other and into the floor, and they were going crazy manipulating the nipple waterer, which is a water pipe with a nipple on the end. All this activity was going on while the Disneyland pigs were sleeping.

When I looked at the brains under the microscope, I found the same thing I found the first time. The barren-environment pigs had greater dendritic growth than the Disneyland pigs, and the greater dendritic growth was in the somatosensory cortex, not the visual cortex.

Bill wasn’t happy about my second experiment, either.

Trying to figure it out, I got to thinking that maybe what makes dendrites grow isn’t the environment. What makes dendrites grow are the animal’s behaviors and actions in its environment. Bill Greenough created a visually complex environment for his rats. There was a lot to look at. But my barrenenvironment piglets had been doing a lot, not seeing a lot. They’d been constantly using their noses to prod and poke each other and the waterer. Greater use of a body part led to greater dendritic growth in the part of the brain that received input from that body part. I think the lack of stimulation revved up their SEEKING system, because when I cleaned their feeders the pigs were so starved for stimulation that they intensely rooted and chewed at my hands. My Disneyland pigs were much less interested in feeder cleaning because they had plenty of fresh straw and toys to occupy their SEEKING system.

Everyone who read Bill Greenough’s studies, including me, automatically assumed that increased dendritic growth was a good thing. But after I saw how my pigs were acting at night when they should have been sleeping, I started to think there can be increased dendritic growth that was abnormal and bad.

Bill didn’t agree, but that’s what neuroscientists believe today. You can have too little brain growth and you can have too much growth. Both things can be pathological. My barren-environment pigs probably had abnormal overgrowth of the dendrites in the somatosensory cortex. This is where my belief came that it is so important to satisfy the SEEKING system to prevent abnormal brain development.

What Makes an Environment Stimulating?

I didn’t come out of graduate school with a biological test for animal welfare, and we still don’t have one today. The only guide people have to judge whether an environment is good for an animal is the animal’s behavior, which gives us insight into its emotion. But that raises quite a few questions. For one, we don’t necessarily know how a captive or domestic animal with good mental welfare should behave, and some animals even hide the fact that their welfare is very poor. Prey species animals such as cattle and sheep hide their pain when they know they are being watched so that predators cannot detect their weakness. When nobody is around they may be lying down and moaning. Another problem with using the animal’s behavior to judge its mental welfare is that captive and domestic animals aren’t free to act the way they would act in the wild. For example, a normal, healthy animal can mate successfully, so if you have an animal that can’t or won’t mate, that’s a red flag. But if a captive animal never has an opportunity to mate, there’s no way to tell whether it would if it had the chance.

Probably for reasons like these, animal welfare researchers have ended up focusing on abnormal repetitive behaviors—stereotypies—to judge animal well-being. Stereotypies are extremely common, easy to see, and definitely abnormal in humans, although both people and animals in certain high-tension moments do have normal stereotypies. If you watch a tennis match, you’ll see lots of them. Roger Federer has a racket-twirling stereotypy, and Maria Sharapova has a little repetitive dance she does while she’s waiting for her opponent to serve. I call these “burst” stereotypies, because they don’t last long. Animals do lots of burst stereotypies. Pigs go crazy bar chewing and bar biting at feeding time. Animals living in the wild also have some burst stereotypies. Polar bears are notorious pacers and figure-eight swimmers in captivity, and they’ve been observed doing “transient pacing” in the wild.

Burst stereotypies are probably always normal, so I don’t worry about them. The stereotypies I worry about are the continuous stereotypies, the ones that go on for hours. Really intense stereotypies—stereotypies an animal spends hours a day doing—almost never occur in the wild, and they almost always do occur in humans with disorders such as schizophrenia and autism. Normal children raised in isolation also have stereotypies. One study of adopted Romanian orphans in Canada found that 84 percent of them had stereotypies. A lot of them rocked back and forth on their hands and knees inside their cribs; other babies stood up, held on to the sides of the cribs, and shifted back and forth from one foot to the other.

One-fourth of the children had self-injurious behavior, or SIB, as well. Self-injurious behavior means the children deliberately injured themselves the way some autistic children do: biting their hands, banging their heads against the wall, or slapping themselves in the face and head. Captive animals can have SIBs, especially primates. Ten to 15 percent of rhesus monkeys living alone in a cage develop self-biting, head banging, and self-slapping.

You never see ARBs or SIBs that severe in the wild. So, when you see them in captivity, that means something is wrong.

85 Million Animals

Georgia Mason and Jeffrey Rushen at the University of Guelph and Agri-Food Canada estimate that over 85 million farm, laboratory, and zoo animals and pets worldwide have stereotypies, including 91.5 percent of all pigs, 82.6 percent of poultry, 50 percent of lab mice, 80 percent of American minks living on fur farms (these are breeding females), and 18.4 percent of horses.
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That’s a lot of stereotypies, and researchers are still trying to come up with the best way to classify the different types of stereotypy. Georgia Mason groups the most common kinds of ARBs this way:

• Pacing-type ARBs—pacing and other similar actions, such as circuit swimming, where a bear or a seal swims the same circuit around its pool over and over again. Over 80 percent of stereotyping carnivores pace, either back and forth or in a figure-eight pattern.
  
• Oral ARBs—bar and fence chewing, obsessive object licking, tongue rolling, and so on. Oral stereotypies are common in all grazing animals, because that’s what they do all day. They graze.
  
• Other ARBs—rocking, repetitive jumping, and so on, or “non-locomotory body movements.”
  

The zoo animals I call the “big pretty animals”—the big predators such as the lions, tigers, and bears—pace. Ungulates, which are the hoofed animals—horses, cows, rhinoceroses, pigs, zebras, llamas—do stereotypies with their mouths. Most of the other animals, including primates and lab rats, develop movement stereotypies in the third category. In human disorders such as autism, the abnormal behavior is usually in the first or third category.

One of the most extreme cases of stereotypy I’ve ever seen was in a female wolf I saw at a wolf shelter. The wolf’s name was Luna. Some crazy lady had been raising wolves in her yard, where she kept them all tied up to trees. No social roaming animal can be tied up all the time; keeping wolves or dogs tied up like that is cruel. They need to travel around and have lots of free social contact with other wolves and dogs. What that lady did was terrible.

The shelter people had rescued all the wolves and built really nice enclosures for them, one hundred feet long, thirty feet wide, and full of trees. They built six pens and put two wolves to a pen, which is fine. Wolf families are generally pretty small, maybe around seven or eight animals, so two wolves to a pen gave each wolf another wolf to socialize with, without the shelter risking putting together a lot of incompatible individuals that might get into fights.