Page 111 - Artificial Intelligence in the Age of Neural Networks and Brain Computing

3. Embodied Cognition 99

Vertebrates have a larger brain and spinal cord is protected by the vertebrae with
ascending sensory pathways and descending motor pathways. Attaching muscles to
internal framework in chordata greatly improves movement. Vertebrates have verte-
bral column, well-differentiated head, and bony skeleton. Finally, mammals devel-
oped neocortex and neocerebellum, which are both prominent in primates. The
longer one studies evolution of neural systems, the more it becomes apparent that
all innovations of neural systems were tightly coupled to changes in organism motor
control. Lampreys, the most primitive of vertebrates, are the only fish species
without cerebellum. The reason is simple; lampreys do not have jaws, or “real”
vertebrae. With jaws and better muscles, modern fish not only acquired cerebellum,
they also developed larger cortex. Transition from aquatic environment to terrestrial
habitats afforded organisms new means of locomotion as illustrated by elaboration
of basal ganglia during the evolutionary transition from amphibians to reptiles.
Reptiles also gained better vision. Emergence of mammals was accompanied with
explosion in special senses, as well as with arrival of neocortex as the major target
of the basal ganglia circuitry, devoted to executing and inhibiting the basal gangliae
mediated control of movement. Eventually, liberation of front limbs in primates for
object manipulation resulted in use of these limbs for meaningful, significant social
gestures in one species of primates and thus lead to the emergence of speech. It is
quite illuminating to observe the growth and interplay of sensor and motor parts
of brain in process of vertebrate evolution:
Evolution of vertebrate brains.