The Limbic System
(pathways of the brain in charge of emotions, feelings, and moods)

1. amygdalar division: feeding, food-search, angry and defensive behaviors related to obtaining food;
2. septal division: sexual pleasure, grooming, courtship, and maternal behavior ;
3. thalamo-cingulate division: play, vocalization and maternal behavior;
4. The hypothalamus: nonverbal behaviors;
5. The hippocampus: aquisition of data into new skills; language development .

The Limbic System (definitions)
1. Those interlinked modules and pathways of the brain in charge of emotions, feelings, and moods.
2. The "entire neuronal circuitry that controls emotional behavior and motivational drives" (Guyton 1996:752).
3. The emotional core of the human nervous system (Cytowic 1993).

Functions of the Limbic System

A great deal of our nonverbal communication reflects happenings in the limbic system. Nonverbal signs, signals, and cues disclose limbic emotions and attitudes more openly and with greater honesty than words.

Evolution: In human beings, the limbic system grew in tandem with the cerebral cortex (Armstrong 1986). Thus, ours is the most emotional - as well as the most intellectual - species on Earth.

1. The limbic system 'plays a key role in the evolutionary survival and eventual success of hominids' (Eccles 1989).
2. Regarding nonverbal behavior: a. the limbic system's amygdalar division promotes feeding, food-search, angry and defensive behaviors related to obtaining food; b. The septal division promotes sexual pleasure, genital swelling, grooming, courtship, and maternal behavior; and c. The thalamocingulate division promotes play, vocalization (e.g., the separation cry), and maternal behavior (MacLean 1993).
3. 'While the cortex contains our model of reality and analyzes what exists outside ourselves, it is the limbic brain that determines the salience of that information' (Cytowic 1993:156).
4. The cerebral cortex 'has more inputs from the limbic system than the limbic system has coming from the cortex' (Cytowic 1993).
5. Many emotional systems, in addition to the limbic system, may exist in the brain (LeDoux 1996).
6. Phylogenetically, the limbic lobe is the oldest part of the cerebral cortex (Willis 1998).
7. The limbic system includes the amygdala, anterior thalamic nucleus, cingulate gyrus, fornix, hippocampus, hypothalamus, mammillary bodies, medial forebrain bundle, prefrontal lobes, septal nuclei, and other areas and pathways of the brain. The hypothalamus, a key player, mediates nonverbal behaviors through the brain-stem reticular nuclei. When excited, the reticular nuclei arouse cerebral as well as spinal circuits. (N.B.: An important two-way link between the limbic system and brain stem is the medial forebrain bundle.)
Copyright © 1998 - 2001 (David B. Givens; Center for Nonverbal Studies)

Amygdala and Immune system

'In the present study we examined the role of the central nucleus of the amygdala in hypothalamic-pituitary-adrenal axis responses to an immune challenge in the form of systemic administration of the proinflammatory cytokine interleukin-1beta (1 microg/kg). We found that bilateral ibotenic acid lesions of the central amygdala substantially reduced adrenocorticotropin hormone release and hypothalamic corticotropin-releasing factor and oxytocin cell c-fos expression responses to interleukin-1,8 suggesting a facilitatory role for this structure in the generation of hypothalamic-pituitary-adrenal axis responses to an immune challenge. Since only a small number of central amygdala cells project directly to the paraventricular nucleus, we then examined the effect of central amygdala lesions on the activity of other brain nuclei that might act as relay sites in the control of the hypothalamic-pituitary-adrenal axis function. We found that bilateral central amygdala lesions significantly reduced interleukin-1beta-induced c-fos expression in cells of the ventromedial and ventrolateral subdivisions of the bed nucleus of the stria terminalis and brainstem catecholamine cell groups of the nucleus tractus solitarius (A2 noradrenergic cells) and ventrolateral medulla (A1 noradrenergic and C1 adrenergic cells). These findings, in conjunction with previous evidence of bed nucleus of the stria terminalis and catecholamine cell group involvement in hypothalamic-pituitary-adrenal axis regulation, suggest that ventromedial and ventrolateral bed nucleus of the stria terminalis cells and medullary catecholamine cells might mediate the influence of the central amygdala on hypothalamic-pituitary-adrenal axis responses to an immune challenge. Thus these data establish that the central amygdala influences hypothalamic-pituitary-adrenal axis responses to a systemic immune challenge but indicate that it primarily acts by modulating the activity of other control mechanisms.' [The central amygdala modulates hypothalamic-pituitary-adrenal axis responses to systemic interleukin-1beta administration; Xu et al]

The Limbic System in Autism

Autopsy and MRI studies have revealed an ímmature development of many structures of the limbic system, including amygdala, gyrate nucleus, and hippocampus, but no damage or loss of neurons. The limbic system represents the mammalian development of emotional attachment, parenting and social behaviors, as well as learning and language development. As warm-blooded mammals, we are dependant on the development of emotional attachment to the parents. We feel good when we are safe, well fed and we know where our parents are. In that state of well being, we learn and develop language and social skills. Conversely, when we are lost, hungry and in danger, we experience panic. That panic involves the immune system and begins with an adrenalin release. The immune system takes over from the emotional system, and we revert to a more primitive state of fight-or-flight, survival instinct. In that state, learning, language development and social skills are not important to survival. We believe that in autism, the immune system is reacting to lutein as if it were a life-threatening pathogen. The particular type of immune response involves the 'alternative pathway activation pathway' (APAP) and is the type of reaction we would see to a cobra venom - it is a life or death situation. The immune system takes charge of the body's vital functions - digestion, metabolism, breathing, heart rate, temperature - and all superfluous activity, including social activity, stops until the reaction ceases. But for the autist, the reaction doesn't cease because lutein is coming into the body too often. In the infant, there are generally few exposures to lutein, but during the second and third years lutein-containing foods begin to enter the diet frequently. The response to the first exposures might be fever, and many parents report fevers during early childhood. The child often begins to refuse some foods. The altered immune system often over-reacts to immune challenges as is seen in the frequent reports of adverse reactions to vaccinations. Then, as the lutein exposure becomes continual, the immune system has to adapt, as continual high fever is dangerous to the brain. The response changes from acute to chronic - control of the digestion, metabolism, hormone and enzyme production. Serotonin transport to the brain is controlled to reduce arousal of the pituatary system to a minimum. The primary focus of the immune system becomes systematic removal of the pigment pathogen and it's breakdown products. This is seen in increased excretion of neopterin and biopterin, prurigo-type eruptions on the skin, and recurrent ear inflamation. Lab reports show unusual patterns of fatty acid and amino acid excretion, Vitamin C metabolism, signs of gut flora imbalance and production of unusual opioid chemicals which the immune system is manufacturing as endogenous stress and pain-reducers. With an ongoing immune system activity, the limbic system switches over to a state of defensiveness and survival. Development of social behavior is arrested in favor of survival, defensive and coping strategies to minimise arousal and social expectactions. Depending on the innate strength of the individual, mental and intellectual functioning may develop, despite the social handicap, in idiosyncratic ways. For some high functioning autists, the strategy of avoidance takes the form of developing unique skills, or intensive reading and studying, or focus on a particular branch of math or science or music.

Removal of lutein from the diet is the first step towards recovery and healing, but there is often a long way to go. After approximately 4 months, the parents report that the child is calmer, happier, more social, more interested. It takes a while longer for language development to move forward, especially for those who were always non-verbal. Our experience after many years into recovery is that the immune system never fully relinquishes control, but coping skills and obsessive behaviors slowly diminish, and focus on normal enjoyment and pleasure increases. Body language becomes more normal and easier to interpret in others. All the senses improve, from a state of confusion and conflict to clarity and sharpness and emotional significance. Our lives take on real meaning and we become less fearful and reclusive and more social and positive in our outlook. Having worked with many thousands of people, we have seen how emotional development increases year on year, so that after 5 years on the diet, a 15 year old may exhibit the typical emotional and social development of a 5 year old, the sexual interests of a 15 year old and the intellectual level of a college student. Although we do not intend to become 'normal', we see the potential of all autists to find meaning and fulfillment, joy and happiness in their lives.