The way scientists answer this animal consciousness question has a big effect not only on their research, but also your medicine cabinet
By Chelsey B. Coombs | Posted March 6, 2015
There’s a rat in a cage with two sides: one bright and one dark. One of the rat’s survival mechanisms is to favor the dark side and avoid the bright side at all costs. But when the rat goes into the dark side of the cage, it gets shocked. After a few shocks coincide with its favorite habitat situation, it remains on the bright side despite its lifelong instincts. Is the rat now afraid of the dark, or is he simply trained to avoid it?
If the rat were a human, he’d probably tell us he’s afraid of the shocks in the darkness, which shows the ability to feel emotions. We know humans have the capacity for consciousness because we think, make decisions, have feelings and a sense of self. And each of us believes that other humans have the same ability. But we don’t yet have the technology to go into the minds of those around us to see and feel what they do.
This distinction is all the more difficult when it comes to non-human animals. We think that our pets are happy when we come home, or sad when we punish them for ruining the brand new couch. But we can’t go into their minds to really know how they’re feeling, or whether they are actually conscious.
The animal consciousness debate has higher stakes than a simple desire to know whether Fido or Fluffy has feelings. It affects how scientists think about and conduct their research on non-human animals, and whether researchers should or should not make assumptions about their subjects’ consciousness while doing their experiments. One side believes scientists must separate the mechanisms that detect and respond to threats from those that create conscious feelings of fear, while the other believes these mechanisms are one and the same.
But this is not a new debate.
“It has been going on forever,” said New York University neuroscientist Joe LeDoux, one of the most vocal of a group of researchers who think non-human animal consciousness isn’t relevant in experiments or even scientifically resolvable. “The basic idea is about how many assumptions scientists are willing to make about consciousness.”
In a 2014 paper in the Proceedings of the National Academy of Sciences titled “Coming to terms with fear,” LeDoux elaborated on his argument, writing, “we can learn quite a bit that is relevant to human feelings from studies of animals without making any assumptions about [their] consciousness.”
But another group of neuroscientists — one of the most vocal being Jaak Panksepp, a neuroscientist at Washington State University — want to factor consciousness into their experiments. In July 2012, at the conclusion of the Francis Crick Memorial Conference on Consciousness in Human and Non-human Animals, Panksepp, along with a White House advisor and other neuroscientists, published The Cambridge Declaration on Consciousness. This declaration, whose signing was witnessed by physicist and cosmologist Stephen Hawking, emphasized that scientific evidence showed clearly that non-human animals have “conscious states along with the capacity to exhibit intentional behaviors.” They argued that all mammals and birds, as well as many other organisms, have the same brain structures and substrates that make consciousness possible in humans, which makes consciousness possible for them as well.
Animal behaviorists have been discussing animal consciousness as long as their field has existed, since Charles Darwin wrote his 1872 book, “The Expression of the Emotions in Man and Animals.” But the issue has deep philosophical roots. Even French philosopher and mathematician René Descartes got in on the debate, writing in his 1637 treatise “Discourse on Method,” “it is more probable that worms and flies and caterpillars move mechanically than that they all have immortal souls.”
John Watson, the early 20th century psychologist known as the father of behaviorism, which focuses on studying outward behavior rather than inward consciousness, had a very similar view. Watson and other behaviorists thought that the only way to understand animals was to observe the causes and effects of their behaviors, rather than to ruminate on whether the animals made conscious behavioral choices. They insisted, for example, that a chastised dog cowering in a corner isn’t feeling fear: He’s actually exhibiting a reflexive behavior triggered by a stimulus — a position bolstered by Russian physiologist Ivan Pavlov’s experiments with salivating dogs.
“The behaviorists took a very strong stance right from the beginning with the ideas that emotions were something you couldn’t measure in a nonhuman animal, so there was no point in going down that route,” said Penn State University biologist Victoria Braithwaite, who studies pain perception, fear and suffering in fish. “It was very clean cut, it was clinical. They thought we shouldn’t be studying things we don’t understand.”
Some researchers, like the founder of psychoanalysis Sigmund Freud tried to delve into how human behavior was influenced or driven by inner feelings and desires. But animal behaviorists almost unanimously focused solely on the observable behaviors themselves, rather than trying to experimentally manipulate or even delve into animal consciousness.
The classical behaviorist point of view has reigned since the 1950s, but there was a silent minority toiling away to try to prove that non-human animals have consciousness.
“[Consciousness] is a century old dilemma that the academic behaviorists decided to close the book on many years ago,” Panksepp said in a recent interview. “I turned out to be among the scientists to open the book.”
Panksepp was inspired by the work of American psychologists Peter Milner and James Olds, who in 1954 discovered the brain reward system. By using electrodes to target certain brain regions in rats, Milner and Olds found they could train the creatures to perform behaviors like pressing levers so they could get more of this deeply rewarding brain stimulation. The brain’s reward system is activated to reinforce certain behaviors that cause pleasure and researchers believe this system is responsible for drug addiction.
Panksepp began using similar deep brain stimulation techniques in his own research. But rather than lying back to enjoy this reward system stimulation, the rats would actually change their behaviors.
“Every animal I stimulated in the rewards system explored [its environment],” he said. “I immediately started seeing this as an emotional system as opposed to just a reward system. It was through this emotional system that animals explore the world,” Panksepp added, and can thus better anticipate threats to their survival.
Panksepp called this branch of the reward system the seeking system. Since then, he and other pro-consciousness scientists have concluded that animals have systems not only for seeking, but also rage, lust, maternal care, panic, play and fear. Researchers were able to map the brain’s so-called play system using rat laughter, a sound that’s too high for humans to hear but sounds like bird calls when manipulated into the human hearing range.
“Every animal I tickled was chirping like crazy and they became very fond of my hand like a little puppy chasing you around,” Panksepp said.
One of his doctoral students began to map the brain areas that caused the rats to laugh, and found that this laughter was, according to Panksepp, a “marker for good feelings” or social joy.
But LeDoux argues differently. He thinks that the neural circuitry associated with fear conditioning, which he argues is a response to a threat, is separate entirely from any circuitry that could create conscious fear.
LeDoux says that in a variety of experiments in humans, subliminal threats were able to cause physiological responses, such as increased skin conductance caused by sweat, without subjects being aware of the threat, even when they are asked to describe how they are feeling at that moment.
“We can trigger these kinds of states that if you measured in an animal, you would say the animal is feeling fear,” LeDoux said. “But if we can’t use that information to conclusively demonstrate that a human is feeling fear or experiencing that state, then we certainly can’t use it every time an animal looks like he may be feeling afraid.”
This uncertainty explains why LeDoux and his camp call this reaction a threat response rather than fear.
Like LeDoux, Braithwaite acknowledges we still don’t have all the information on human consciousness, but in the animal consciousness debate she sides with Panksepp.
“It’s the 21st Century. We can put people on the moon but we still don’t understand our own consciousness,” she said. “I think we need to recognize that we’re part of an evolutionary progression and it would be very bizarre for animals to not have forms of consciousness.”
This isn’t simply a war of competing factions who just want to be right. According to both Panksepp and LeDoux, whatever direction the field goes in will affect how scientists look for new human psychiatric medications and how animals in research laboratories are used in experiments.
Panksepp, for instance, developed a new antidepressant that is currently undergoing FDA testing. “It is a molecule that facilitates social joy, mainly rat laughter. Lo and behold, we developed molecules that were safe and non-addictive to modulate this complex neurochemical pathway, and it’s been in human testing now for four years.”
While Panksepp believes researchers should take animal emotions into account when looking for these new medications, LeDoux believes scientists must separate the mechanisms that detect and respond to threats and the mechanisms that create conscious feelings of fear.
LeDoux says behavioral therapy addresses non-conscious brain circuitry more directly, while cognitive, or talk, therapy addresses the conscious circuitry. But many therapists use both methods. He argues that from a neuroscientific standpoint this is not as effective at helping patients, because the different predisposing factors that cause psychiatric problems are susceptible to different treatments.
“If we’re confusing the experience and the automatic detection and response systems, we’re not really doing justice to how we’re curing anxiety disorders,” LeDoux said. “We’re not being clear about what’s controlling different aspects of it and how those different things should be treated in people.”
There’s a lot more at stake for the rat in the dark and light cage than most would expect, and the way researchers handle their thinking of the rat’s conscious and unconscious experiences has great implications for human applications. For now, this shocking controversy continues on.
No comments:
Post a Comment