The pilot and autopilot within our mind-brain connection

Have you ever driven to work so deep in thought that you arrive safely yet can’t recall the drive itself? And if so, what part of “you” was detecting cars and pedestrians, making appropriate stops and turns? Although when you get to work you can’t remember the driving experience, you are likely to have exquisite memory about having planned your day.

How does one understand this common experience? This is the question posed by Professor of Biology, John Lisman and his former undergraduate student, Eliezer J. Sternberg, now in medical school, in a recent paper in the Journal of Cognitive Neuroscience. Lisman explains that once a task such as driving has become a habit, you can perform another task at the same time, such as planning your day. But looking closer at these two behaviors, driving and planning, one can see interesting differences. The Habit system that is driving you to work is non-flexible: if the new parking regulations at work require you to go left instead or right, the likelihood that you’ll go right is very high. On the other hand, if you heard yesterday that your boss has scheduled a group meeting for noon, the likehood that you’ll plan your day accordingly is high. In other words, your non-habit system is flexible.

What interests Lisman and Sternberg is the relationship of the habit/non-habit systems to concepts of conscious vs unconscious. These concepts were popularized by Freud, who posited a duality of the human mind. Behavior can be influenced by both the conscious system and unconscious system. Freud compared the mind to an iceberg——with the small conscious system above water and the larger unconscious system below. Modern cognitive neuroscience now accepts this duality.

The mind can be described as having an unconscious and conscious part. And the brain can be described as having both habit and non-habit systems. Lisman and Sternberg argue that these two views can be merged: there is a habit system of which we are unconscious and a non-habit system of which we are conscious.

This simple equation turns out to have enormous implications for research on the mind-brain connection. Experiments on consciousness are done in humans because you can ask them to report their awareness, something you can’t do with animals. On the other hand, there are many invasive procedures for studying what’s happening in the brain of animals. So how can you study consciousness in rats?

Lisman and Sternberg provide a simple answer — ask whether rats have habit and non-habits. Scientific literature demonstrates that rats indeed have both habits and non-habits. For instance, when a rat comes to a choice point on a maze (and the reward site is to left), rats display very different behavior depending on how much experience they’ve had with that maze. With relatively little experience, rats pause at the choice point and look both ways before making a decision; in contrast, a highly experienced rats zooms left without stopping. Experiments have shown that different parts of the brain are involved in these two phases. Lisman and Sternberg make two conclusions: first, that rats, like us, have conscious and unconscious parts of the brain and second, that from experiments on rats we can learn to identify the parts of the brain that mediate conscious vs unconscious processes.

In their paper, Lisman and Sternberg also discuss potential objections to their hypothesis, and suggest further tests.

(Photo: GETTY)

University of Toronto study demonstrates impact of adversity on early life development

It is time to put the nature versus nurture debate to rest and embrace growing evidence that it is the interaction between biology and environment in early life that influences human development, according to a series of studies recently published in a special edition of the Proceedings of the National Academy of Sciences (PNAS).

"Biologists used to think that our differences are pre-programmed in our genes, while psychologists argued that babies are born with a blank slate and their experience writes on it to shape them into the adults they become. Instead, the important question to be asking is, ‘How is our experience in early life getting embedded in our biology?’" says University of Toronto behavioural geneticist Marla Sokolowski. She is co-editor of the PNAS special edition titled "Biological Embedding of Early Social Adversity: From Fruit Flies to Kindergarteners" along with professors Tom Boyce (University of British Columbia) and Gene Robinson (University of Illinois).

Sokolowski, who is a University Professor in the Department of Ecology & Evolutionary Biology (EEB), the inaugural academic director of Uof T’s Fraser Mustard Institute for Human Development and co-director of the Experience-based Brain and Biological Development Program (EBBD) at the Canadian Institute for Advanced Research (CIFAR) says that relatively little is known about the gene-environment interplay that underlies the impact of early life adversity on adult health and behaviour.

In one of the studies in the series, Sokolowski and her colleagues found that chronic food deprivation and lack of adequate nutrition in the early life of the fruit fly Drosophila melanogaster had significant impact on adult behaviour and quality of life. Fruit flies are especially useful for genetic studies because they share a surprising number of qualities with humans, are inexpensive to care for and reproduce rapidly, allowing for several generations to be studied in just a few months.