Page 61 - Mind Games The Aging Brain and How to Keep it Healthy

The Intelligent Mind • 45

simple a task as waving good-bye can become impossible to
26
perform and impossible to learn if the SMAis damaged. The
premotor cortex and the basal ganglia aid in the planning and
implementation of the path of the movement. The posterior
parietal lobe, important in spatial ability, interacts with the
premotor cortex.
The process of movement actually is accomplished with
two loops through the system: a complex loop and a motor
loop. The complex loop begins with instructions from the
frontal lobes. The instructions then are fed through the basal
ganglia and caudate nucleus portions and are sent to the
thalamus. Then the information is fed back through the
frontal lobes and into the motor loop. The motor loop begins
with M1, where fine motor control is located. Some of the
neurons located in M1 have direct access to the spinal col-
umn. The cerebellum is included in the pathway, because it
appears to be the site of automatic motor responses (those
skills that are “second nature”).

SMA M1

Premotor
Cortex

Head of
Calidate

Putamen
Cerebellum

Figure 2-12 Location of the motor control system