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“of all points in the rehabilitation process following TBI, none is more important than that at which the individual who has sustained the TBI begins to return to the community, attempting to pick up the threads of a previous life style, or to construct a new life which brings some satisfaction.” — Traumatic Brain Injury, rehabilitation for everyday adapting living. Jennie Ponsford -
MENTAL SIMULATION AND THE MOTOR SYSTEM
The moment Holmes emptied his gun was the final stage of a set of processes by which
his action was planned in response to the dramatic event he witnessed. Do you think
his reasoning processes relied on the kinds of logical deductions and inductions we discussed in Chapter 10? In fact, there is evidence that a different sort of cognition underlies our reasoning in action situations. Specifically, one way we reason is by forming
and transforming mental images of possible actions, and “observing” the consequences of those actions. This makes sense because imagery and perception share most
of the same neural mechanisms (Ganis et al., 2004; Kosslyn et al., 1997; Kosslyn et al.,
2006). Thus, “watching” the events in a mental image can change our behavior, much
as can watching another person’s behavior. Indeed, many athletes believe that mentally
rehearsing their movements before executing them on the field helps them to perform
better, and research supports this belief. It has been demonstrated that motor imagery—mentally simulating an intended action without actually producing it—has a
positive effect on subsequently performing that action (Feltz & Landers, 1983).
Not only can motor imagery guide our motor cognition, but our motor cognition in turn can affect our motor imagery. Converging evidence from several sources
indicates that motor imagery involves processes involved in programming and preparation of actual actions. The essential difference is that in the case of motor imagery,
the action is not performed. Still, the processes underlying motor cognition can direct
the way mental images are transformed. In this section, you will see that the mechanisms that allow us to produce actions also allow us to anticipate the likely consequences of performing an action.
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THE NATURE OF MOTOR COGNITION
You may never have thought much about how you plan and control your movements, but even a moment’s reflection should make you aware that your actions typically are not reflexes, triggered by an external stimulus (such as occurs when you
yank your hand back from a hot stove), but rather are the visible manifestation of a
series of mental processes. A key idea is that these same mental processes can be used
in cognition, even when they do not result in a specific movement. To see how the
processes used to plan and guide movement can also be used in reasoning and problem solving, we must begin by considering the nature of motor processing.
Many contemporary researchers assume that there is a continuity between planning and enactment. In this view a movement is considered to be a voluntary displacement of a body part in physical space, whereas an action is a series of
movements that must be accomplished in order to reach a goal. Indeed, actions are
planned with respect to a specific goal. For example, if you are thirsty and want to
take a sip of coffee, you might look at your coffee mug, reach toward it, wrap your fingers around the handle, lift the mug, and bring it to your lips. Motor cognition encompasses all the mental processes involved in the planning, preparation, and production of our own actions, as well as the mental processes involved in anticipating,
predicting, and interpreting the actions of others.
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“ The daunting complexity of the visual system is functional as well as structural, as is
shown in Figure 2–3. The pathways and their many ramifications are not one-way
streets. Most visual areas that send output to another area also receive input from that
area; that is, they have reciprocal connections—for example, LGN provides input to V1
and V1 provides other input to LGN. This dynamic arrangement reflects an important
principle of visual perception: visual perception—in fact, all perception—is the product
of bottom-up and top-down processes. Bottom-up processes are driven by sensory information from the physical world. Top-down processes actively seek and extract sensory information and are driven by our knowledge, beliefs, expectations, and goals.
Almost every act of perception involves both bottom-up and top-down processing.
One way to experience the distinction consciously is to slow part of the topdown contribution. Look at Figure 2–4. There is certainly something there to be
seen: bottom-up processes show you lines and define regions. But if you play with
the image mentally and consider what the regions might signify, you can feel a topdown contribution at work. The image could be … a bear climbing up the other side
of a tree! Whether or not you came up with this solution yourself, your appreciation
of it depends on top-down knowledge: your knowledge of what a tree and a bear’s
paws look like, your knowledge of how bears climb trees. This kind of knowledge
not only organizes what you see, but also can even modulate the processes that created the representations of the lines and regions.
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“the main visual pathways in the brain can be thought of as an intricate wiring pattern that links a hierarchy of brain areas. Starting at the bottom, the pattern of light intensity, edges, and other features in the visual scene forms an image on the retina, the layer of cell that responds to light, called photoreceptors, and nerve cells at the back of each eye.” — The Structure Of The Visual System-Smith Kosslyn -
structure of a neuron…
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“brain activity arises primarily from the activities of neurons. sensory neurons are activated by input from sensory organs such as the eyes and ears; motor neurons stimulate muscles , causing movements.” — cognitive psychology, mind and brain. Edward E. Smith, Stephen M.Kosslyn -
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“traumatic brain injury (TBI) affects an estimated 10 million people worldwide and causes significant physical, emotional and cognitive disabilities among those affected. A TBI is an injury to the head or brain caused by internally inflicted trauma. The events that lead to TBI vary by population. Among civilians, motor vehicle accidents are the leading cause of TBI-related deaths; Among young children and older adults, falls are a major cause of TBI and among soldiers blasts.” — Cognitive rehabilitation therapy for traumatic brain injury, Institute of medicine -
