Final answer:
Stimulation of the limbic system in lower animals can elicit instinctual behaviors like fighting, mating, and nest building, with the amygdala and nucleus accumbens being key structures in these responses. Research indicates that the motivation and capability to engage in such behaviors are controlled by separate neural systems within animals.
Step-by-step explanation:
Among lower animals, stimulation of various areas of the limbic system can trigger instinctual behavior such as fighting, mating, or nest building. The limbic system includes structures such as the amygdala and nucleus accumbens, which play significant roles in behavioral responses. Animal research has shown that damage to these areas can lead to a decreased motivation to engage in behaviors like sexual activity, albeit the capability to perform these acts remains unaffected.
This finding indicates that the physiological mechanisms underlying the ability and motivation to act are governed by distinct neural systems. Instincts are complex patterns of unlearned behavior, more prevalent in lower animals than in humans, and include a broad range of events such as maturation and changes in seasons. Examples of these instinctual behaviors include birds building nests, dogs shaking off water, and salmon swimming upstream to spawn, all of which are innate and do not require prior learning.