will does not exist. Inherited instincts within the limbic system
(LS) make the final decisions of your mind. Instinctual behavior is
triggered by the programmed combinatorial codes of the nervous
system. The evolutionary need for survival generated system codes,
which overrule the will of the individual. It is not your will, but
the LS, which chooses your behavioral response - merciless attack, or
noble self sacrifice. You can personally verify this process.
Your will is exercised by the the highest known intelligence in the universe, residing in the prefrontal regions (PFR). The PFR was the first decision maker. But, evolution took away its power to make the final decision, when it added a multitude of other decision makers. Because, survival decisions demanded many patterns of behavior. Focused behaviors were needed when attacking the enemy, escaping from danger, feeding, or resting. Nature assembled innumerable behavior programs to achieve each objective. Each behavior pattern had to bypass alternative options. There can be only one final choice. An animal had to either eat grass, or quench thirst.
Intuition was the instant elimination process, which inhibited alternative behaviors and focused all available resources to achieve a particular objective. Each behavior pattern required an "either, or" decision. Nature used an existing mechanism for this eliminative process. Francois Jacob noted this adaptive quality of evolution. “In contrast to the engineer, evolution does not produce innovations from scratch. It works on what already exists, either transforming a system to give it a new function or combining several systems to produce a more complex one.” The LS adapted the control strategy exercised by the spinal cord to make the decisions of the mind.
System – Evolution Adapts
The spinal cord manages interaction of over 60,000 motor neurons. Using feed back/feed forward links, the spinal cord relaxes all the opposing muscles for all contracting muscles. This incredibly coordinated action occurs thousands of times per second, when you sing a song or write a letter. The limbic system has a million fibers, which carry feed back/feed forward links between a massive range of conflicting emotion signals. Fear, sadness, disgust, contempt, curiosity, surprise, love, pleasure, embarrassment, guilt, and shame impact on behavior. Competing with each other, emotions are generally agreeable, or disagreeable. The LS grants control to a single emotion, while inhibiting conflicting ones. Anger gives way to fear. Nature adapted the spinal cord motor control strategy in the LS to manage emotional controls.
Limbic System – PFR Made Unemotional Decisions.
Evolution assembled innumerable pattern recognition capabilities to animals. It gathered regions to identify touch, odors, taste, vision and sounds. Association regions developed to recognize objects and events from these identified sensory inputs. Early on, the PFR used this data to make global decisions for animals. The spinal cord and regions below followed those decisions. The nuclei, which perform PFR functions are clusters of neurons in birds and reptiles, while they are constructed as layers of neurons in mammals. Because of the structural differences, some scientists questioned the existence of a counterpart to the PFR in birds and reptiles. But, genetic research has confirmed that this essential and focused decision making function exists in all animals.
Detlev Arendt identified a common set of genes specifying the essential PFR functions, that exist in the common ancestors of annelids, insects and vertebrates. These master regulatory genes specify the identity and positional information of the forebrain, midbrain, hindbrain and even the cerebral cortex. Such genes define the mature characteristics of the region. Detlev Arendt identified the patterns and sequences of genes which were expressed in the cortex of mammals and the “pallium” of birds and reptiles. The same patterns were expressed in the “mushroom bodies,” which are the sensory-associative regions for annelid worms. In the early stages, the PFR enabled the rational evaluation of data, without resort to emotional responses. But, in the end, it is the LS, which chooses to override the options to behave rationally, or emotionally, to meet the urgent demands of the body.
System – The Hypothalamus
The LS ring is linked to numerous control systems. The hypothalamus receives inputs about the needs of the body. Being older than other organs in the LS, the organ controls the reproductive, vegetative, endocrine, hormonal, visceral and autonomic functions of the body. Caloric and glucose receptors indicate the need for food and nourishment. Osmo-receptors indicate a a need for water. The organ has thermo-sensitive neurons, enabling it to decide to respond to excessive external cold or heat. The organ is sensitive to olfactory inputs related to sexual status.
The hypothalamus acts reflexively, in an almost on/off manner, seeking to maintain the experience of pleasure and escape or avoid unpleasant, noxious conditions. One region of this organ activates the sympathetic system, which heightens emotional arousal, while another region energizes the parasympathetic system, which dampens down the metabolic and somatic correlates of emotional tension. Combinatorial codes of the feed back/feed forward LS links enable the hypothalamus to inhibit alternate options to meet urgent bodily needs.
Limbic System - The Amygdala
Early on, the amygdala became a component of the LS. It has the ability to remember sensory inputs, which hold a potential for pain. To save time, the sensory inputs to the amygdala bypass the inputs to the cortex. Nociceptive neurons fire in response to painful stimuli such as high temperature, low pH and tissue damage. Nociception has been documented in non-mammalian animals, including fish nematode worms, sea slugs, and fruit flies. When amygdala senses danger, it triggers the fear, or anger emotion. The organism becomes aroused and alert. Electrical stimulation of the lateral amygdala initiates anxious glancing and searching movements of the eyes and head. When these signals reach the hypothalamus, the organ initiates pain avoidance behavior. Combinatorial codes in the LS decide when the signals from the amygdala should over ride other behavior options.
Limbic System – The Hippocampus
A part of LS, the hippocampus assists in the storage of combinatorial memories in the space/time/emotions context. An emotion indicates a crisis point, where a decision was made during the day. The hippocampus stores episodic memories in the context of the geographic location, where the emotional event occurred. The hippocampus has spatial maps maintained by "place" neurons linked to specific environmental features and landmarks. Hippocampal damage causes a loss of the ability to store and recall episodic memories.
During REM episodes of sleep, the hippocampus activates those regions, which were active during the experience of an event, strengthening the combinatorial links of the emotional signal to the sensory event memory. Subsequent recall of the emotion recalls the event. The hippocampus grants the LS the time critical link to real time decision memories.
Limbic System – The Septal Nuclei
The septal nuclei contributes to the energization of focus as well as the inhibition of alternate options by the LS feed back/ feed forward circuits. Signals from the septal nucleus energize the system on a single focus, while inhibiting activity in unrelated regions. This group of neurons has copious links to the control centers in the amygdala, the hippocampus, the hypothalamus and the brain stem reticular formation. Activation of the septal nucleus stimulates neurotransmitter production, which motivates the organism. It also has an inhibitory-GABAnergic effect, which empowers intuition by inhibiting irrelevant neural activity. The septal nucleus influences the generation of rhythmic slow activity (theta) which indicates hippocampal arousal connected to learning and memory. Lesions in the septal nucleus abolish hippocampal theta and impact on memory.
Limbic System – The Insular Cortex
The insular cortex enables the LS to make self and socially aware decisions. It is a portion of the cerebral cortex folded deep within it. Its front portion is considered to be a part of LS. The insular cortex has access to bodily responses including movements of the body; by pain, temperature, itch and changes in local oxygen status. These inputs enable the organ to perform the function of identifying the self as an independent entity. Mirror neurons within the organ recognize the implications of social interactions to trigger a range of social emotions, including shame, guilt and compassion.
Limbic System – Opposing Forces
Decisions of the mind range between numerous conflicting options. Early in the course of evolution, nature developed a system to manage the opposing forces exerted by muscles. Muscles can only contract. When one muscle relaxes, an opposing one contracts. Each one of the 60,000 motor neurons in the spinal cord has up to 20,000 interneurons, which report back the movements of other muscles. Feedback links inform the muscle of actions already taken and feed forward links, of actions about to be taken.
Combinatorial memories within a nerve cells cause the cell to recognize incoming patterns of impulses and fire to activate or inhibit muscles. Since muscle movements are not computed, but learned through habit and practice, combinatorial memories manage this process. The smooth movement of a centipede or the skilled movements of a dancer are both dependent on microscopically precise combinatorial memories. These memories control the exact flexing of a muscle with millisecond precision. The selection of the behavior of the moment is decided by the LS with inherited and acquired combinatorial memories.
Limbic System Decisions – Evolutionary Adaptation
The spinal cord coordinates complex and opposing neural interactions. The limbic system has a million fibers, which carry a massive range of control signals along with complex and conflicting emotion signals. Fear, sadness, disgust, contempt, curiosity, surprise, love, pleasure, embarrassment, guilt, and shame impact on behavior. Competing with each other, emotions are generally agreeable, or disagreeable. Feedback/feed forward links within the LS grant control to a single emotion, while inhibiting conflicting ones. Resentment gives way to respect. In the LS, nature adapted the spinal cord motor control system to suit the new emotional controls.
Limbic System – Emotions Gradually Overrule
The LS assembles a massive store of combinatorial memories, which shift the focus of the mind with maturity. Evolutionary processes developed to inhibit the more primitive instincts to enable more cultured decisions. The hypothalamus controls essential homeostasis by motivating the organism with pleasure and triggering avoidance behaviors. Infant development witnesses the inhibition of instinctive responses by the wisdom of higher levels. During the first few months, elementary touch, hunger and body movement sensations trigger screaming, crying, or rudimentary smiles and gurgles of pleasure. With development, these responses are overruled by the rational decisions of the PFR, or the emotional outbursts of the amygdala, or the insular cortex. Intuition and combinatorial codes enable the LS to focus of the mind instantly on a single objective.
Limbic System – Codes Overrule Prefrontal Will
You can personally verify that your LS over rules the decisions of your will. Your will is expressed by your PFR, when you consciously decide to lift up your arm. Your will is in control when you are alone in your room. But, if your PFR decides to raise your arm high, when you are standing in an elevator with other passengers, your hand will not move. The LS has over ruled PFR, since the action is inappropriate. You can verify that the decisions of the system bypass consciously willed decisions, when they do not pass the Worthwhile, Appropriate, Safe, or Practical (WASP) criteria.
The system will not implement a conscious decision, if it does not fit the WASP criteria. Conscious decisions are initiated by the PFR, while emotional decisions are initiated by the amygdala, or the insular cortex. It is obvious that only the vast inherited wisdom of combinatorial codes can enable the LS to make critical survival choices between competitive demands, bypassing your PFR.
This page was last updated on 14-Jan-2016.