When neutral proteins are produced, mild ASD will occur due to inadequate production of synaptic adhesion proteins (neuroligin, neurexin, MDGA1 and MDGA2) needed for normal mood, speech and behavior. When a toxic protein results it would destroy the target sites, and impaIr their functions.
On rare occasions, a mutant synaptic adhesion protein may have an enhancing protein may lead to a super-functioning ASD patient. Synaptic protein abnormalities have been associate with autism and schizophrenia. In order to easily recognize an abnormal pattern of child development, one needs to have a sense of what is normal.
After having two normal kids a mom might get a sense of what is normal in child development. But a new mom will need help knowing what to expect. She needs to know that at birth, a newborn baby will have a grabbing and reaching behavior or the startle reflex. The newborn is also able to initiate facial grimace, as well as cry and cling for attachment.
As early as 1 week a newborn can distinguish mom's smell from dad's smell. A normal newborn, in the first couple of months is attracted to bright, colorful, moving objects, and can distinguish voice sound from ordinary noise. Prior to the 8th week, the baby exhibits reflex (endogenous) smile. But by week 8, the baby responds to faces with a smile (exogenous or social smile). By week 12, the smile becomes selective for familiar faces only (preferential social smile). The newborn quickly learns to draw attention to personal needs by crying aloud.
The loud cry usually builds up from unhappy face to grunting to sobbing to cry outburst with tear stream. As the child grows older he/she learns to kick off bed covers in protest and roll into ready to crawl position with head lifted up and eyes scanning for parents. In general the manifestations of autism are related to the child's tendency to be disinterested in the environment, to be inflexible with habits and mannerisms, and to be emotionally numb. Two early sign of inflexibility often overlooked in a newborn are the selective feeding on only one breast and selective sleeping in only one position.
The autistic newborn may also only fall asleep when the room is pitch dark or clutching a specific part of his/her body. Some may insist on having their thumb in their mouth before they can fall asleep. One of the earliest obvious suggestions that something may be wrong is the absence social smile between three to four months after birth.
There may also be absence of eye contacts or tracking eye movements. It becomes more obvious that something is wrong between ages 6 and 12, when a child fails to develop normal emotional, speech and play patterns, and makes only repetitive sounds and hand movements.
Synaptic failures between primary cortical sensory areas (visual, auditory, and somatosennsory) and association cortex, prevents learning and memory formation that occurs through the association of particular emotions with specific stimuli, place and objects. Normally, the smiley face of a mom breastfeeding her baby stimulates increased dopamine release in the pleasure center (nucleus accumbens), and causes the baby to return a smile whenever a physiologic need is met.
The pleasure of social interaction by itself may directly create a positive memory in a normal child through the hippocampus without nuerotransmitter surge in nucleus accombens. The script recorded in the hypocampus is played over and over by the autistic kid for every emotional situation, until there occurs a strong intrusive override by way of teaching.
This accounts for the repetitive and non-interactive, domineering style of communication exhibited by autistic individuals. A negative emotion creates a diminished desire for the stimulus, by reducing the level of dopamine, which normally causes a craving for the stimulus. This association of negative emotion with withdrawal occurs in the amygdala, the limbic nucleus for harm avoidance.
Dopamine reduction is produced by a surge of serotonin into the synapses, which creates the feeling of satisfaction and switches off the stimulus. Two other neurotransmitters, mGluR2 and mGluR3, inhibit the opening of dopamine receptors, thereby further reducing its craving effect and increasing the harm avoidance response. The craving response and harm avoidance response are modulated by the ventromedial prefrontal cortical association area, which is the center for problem solving reward with a strong kink to the limbic system.