246 Maternal Antibodies to Fetal Brain Neurons and Autism
Studies Using Rodent Models
Parallel to the studies described above that were carried out in rhesus
macaques, scientists duplicated the studies in mice in which pregnant mice
were infused with a single intravenous injection of human maternal plasma.
The plasma contained neuroantibodies that were reactive to the 37‐ and
73‐kDa banding pattern. The offspring from the mice exhibited increased
anxiety and response to stress, along with impaired motor and sensory
development [20]. The investigators concluded that the offspring born to
pregnant mice injected with IgG from mothers with autistic children, and
not from mothers with normally developing children, showed some of the
symptoms seen in ASD, including alterations in sociability and increased
activity and anxiety [22].Why Do Some Autistic Children Have Bigger Brains?
The normal human offspring is born with limited processing and behavioral
abilities since at the time of birth, the neural circuitry is still limited in many
brain regions, most especially in the compartments representing higher
order reasoning, language, social, emotional, and self‐awareness functions.
Throughout the first years of a newborn, the rise of functional ability
depends heavily on the establishment, generation and improvement of innu
merable eruptions of neural circuitry. At this stage of neurogenesis, syn
apses are being formed between near and distal neurons at lightning speed.
These processes are integrated with high speed experience based learning to
very high neuronal proliferation, and differentiation, and myelination. This
is one of the most important periods of a newborn’s learning processes that
permanently stabilize adaptive connections. These essential growth and
selection processes follow regionally ordered and precisely timed sequences,
and as a result neurobehavioral functions emerge and become refined in an
orderly hierarchical fashion during the first year of life and continue in a
similar manner for a few more years. During the first year and subsequent
two years, the rate of brain growth and the regions where the brain growth
is critical appear to differ significantly in ASD babies as compared with nor
mal babies [23] (Figure 8.4).
It is during the first few years of brain growth combined with the experiential
learning period that an ASD baby is differentiated from a normal one. During
the first year it is not possible to observe any clear‐cut difference between the
two babies but innumerable retrospective studies and parental observations
based on subtle motor, sensory, attention and social behavioral abnormalities
show differences may be present as early as the first or second year of life [23].
However, around 2–3 years, ASD babies fail to reach normal language and