Paul Valery said "The future is not what it used to be"
We always believe that we are 'in the moment' and that we can anticipate the future but recent research has shed light on these very processes. Contrary to what one might imagine, the way we interact with the world is not a simple matter of seeing (or touching, or smelling) and then reacting. Our brain really lives in the past since the neurons and neural connections that make up our sensory systems are far too slow for this to work. So how does our brain get around what is past and what is now vs what is the future.
Collaborative work by Caltech,MIT and McGill University, offers the first neural evidence that voluntary limb movements are guided by our brain's prediction of what will happen an instant into the future. According the the reserchers, the brain is generating its own version of the world, a 'forward model,' which allows you to know where you actually are in real time. It takes the delays out of the system.'
In an attempt to understand the interface between thought and implanted neural prosthetic devices, the research in Andersen's laboratory is focused on understanding the neurobiological underpinnings of brain processes, including the senses of sight, hearing, balance, and touch, and the neural mechanisms of action. Andersen's group focuses on a more high-level area of cortex called the posterior parietal cortex (PPC), which is where sensory stimuli are actually transformed into movement plans.
In their experiments, Andersen and his colleagues trained two monkeys to use a joystick to move a cursor on a computer screen from a small red circle into a green circle, while keeping their gaze fixed on the red circle. The monkeys typically generated curved trajectories, but to increase the curvature one monkey was trained to move the cursor around an obstacle. The obstacle (a large blue circle) was placed between the initial location of the cursor and the target circle, and the monkey had to guide the cursor around the obstacle, without touching it, and over to the green circle. As the monkeys conducted the tasks, electrodes measured the activity of neurons in the PPC. This allowed Andersen and his colleagues to monitor signals--commands for movement--in real time.
The studies showed that neurons in the PPC produce signals that represent the brain's estimation of the current and upcoming movement of the cursor. "An internal estimate of the current state of the cursor can be used immediately by the brain to rapidly correct a movement, avoiding having to rely entirely on late-arriving sensory information, which can result in slow and unstable control."
"The idea is that you feed back the command you make for movement into those areas of the brain that plan the movement (i.e., the PPC)," Andersen says. "The signal about the movement taking place is adjusted to be perfectly aligned in time with the actual movement--what you're moving in your head matches with what you're moving in the real world." The effect is akin to an athlete visualizing his performance in his mind. Studies have previously shown that these simulations of movement trajectories run through the posterior parietal cortex, and run at actual speed, taking the same amount of time as the activity would in real life.
Forward Estimation of Movement State in Posterior Parietal Cortex
PNAS