Living and Adapting to Its Own Habitat - Building the Most Complex Structure on Earth - page 230

Among the most complex innate behaviors regulated by CPGs are the elec-
trogenic (production of electric discharges for communication with conspecifics,
navigation, or prey localization) and electroreceptive phenomena in fish. Many of
these fish have even evolved complex mechanisms of avoiding the jamming elec-
tric signals emitted by conspecifics by changing their electric signals' frequency
( Heiligenberg et al., 1996; Metzner, 1999 ). In the vertebrate brain, the hypothala-
mus plays a central role in regulating innate behaviors and its lesion abolishes innate
defensive behavior and avolitional eating ( Manoli et al., 2008 ). For instance, activa-
tion of the hypothalamic ventromedial region (VMH) sends permissive signals to the
midbrain centers for lordosis and regulates the reproductive behavior, including its
synchronization with ovulation ( Pfaff, 2005 ).
Learned behaviors in metazoans are acquired by experience during their lifetime.
Like innate behaviors, learned behaviors are patterned by specific neural circuits,
but, unlike them, they may be perfected over time. All learned behaviors rely on the
presence of innate motor programs or program preadaptations in the CNS. This may
explain why some learned behaviors, through repeated practicing, may be performed
automatically, unconsciously, like innate behaviors.

The emerging picture, then, whether it be the wholly innate performance of spiders, the
goal-directed learning of infants, or the plastic learning we see in piano playing, is that
all are routines stored, either from the outset or ultimately, as discrete neural programs.
Gould (1982)

Learning new behaviors may be facilitated by the flexibility of neural circuits,
which may modify connections between neurons in order to generate new behaviors.
Neural circuits sometimes are conserved after the loss of a behavior. When ancestral
conditions in the environment recur, learning new behavior may result from activat-
ing the inactive ancestral circuit.
Although learned behaviors are acquired through experience, they also have a
heritable component. Since any inherited trait is, even unconsciously, considered a
function of genes, let us briefly look at the role genes play in behavior. As mentioned
earlier, almost all behavior implies a motor action. It is not easy to see how one or a
number of genes can determine an adaptive action in response to an external stimu-
lus. Even a simple behavior, such as walking, involves activation and coordination
of numerous leg muscles and joints and even most muscles and joints of the ani-
mal body. The commands for activation and coordination of muscles come from the
CNS, not from genes. This is not to say that genes are not involved in walking (gene
defects may prevent animals and humans from walking), but simply that they do not
have the information necessary for walking or any other behavior. It may be argued
that genes may be necessary for the establishment or functioning of neural circuits
determining behaviors, but so are many metabolites:

Any behavior requires the functioning of a multicellular circuit beginning with input
to the nervous system, propagation and interpretation of that input in the CNS, and
output via neurons that direct a response via neuromuscular, or neuroendocrine sys-
tems, or both.

Baker et al. (2001)