Biological Bases of Behavior

Neurotransmissions

Neural communication is the information system that helps connect our biological process to our psychological process as an information highway. Nerve cells are at the very basis of this communication. Each neuron consists of a cell body with extended branches. These branches are called dendrites, and they receive information to then carry it back to the cell body.

At this point, the long arm of the cell body, the axon, takes the message to the other neurons. This is kind of like the game you may have played as a child, the telephone game.

A zoomed-in image of a neuron. pixabay.com

Neural Communication

Think of neural communication as a huge telephone system. The meeting point between each neuron, or telephone, is called a synapse. Do all the neurons touch at the synapse or meeting point? No, they don't; this is called a synaptic gap. The synaptic clefts come incredibly close to each other, but they do not come in contact.

At the synaptic gap, there is a booming release of chemicals! This is called a neurotransmitter. The neurotransmitter allows for the absorption of the chemical that was released in the action. Once the sending neuron has a moment to reabsorb the excess or extra neurotransmitters, it becomes a moment of reuptake.

Why are these factors important to that of behavior? Neurotransmitters such as dopamine, serotonin, and norepinephrine are in charge of certain aspects and behaviors for humans. For example, when a neurotransmitter releases dopamine into our system, there is a change in our emotions. It also influences our attention.

The Nervous and Endocrine System

The nervous system has a lot of key players in the performance of our day-to-day living. There is the taking in mass amounts of information, the making of decisions, and then conveying that to the many areas of our body.

Who are the key players in all this information processing?

The Nervous System

The brain and the spinal cord are the decision-makers of the central nervous system (CNS); you can think of them collectively as the team captain. The assistant to the captain is the peripheral nervous system (PNS), which takes the messages from the central nervous system and shares it with the rest of the body or team members. Nerves are the links between the muscles, glands, and sensory receptors of the body. For example, the olfactory nerve of the body is in charge of smell. The nervous system information travels to three different types of neurons; sensory neurons, motor neurons, and interneurons. The sensory neurons are the message carriers from the sensory receptors to the brain and spinal cord. The motor neurons take messages and instructions from the central nervous system to the glands and muscles. Those messages are then processed by the brain by the interneurons, or the body's internal way of communicating.

The Peripheral Nervous System

The peripheral nervous system has both the somatic and autonomic components that make it one large system. The somatic nervous system is responsible for our skeletal muscles. Our organs also have someone calling the shots; our autonomic nervous system (ANS). The ANS controls our glands and inner organ muscles and such functions as our heartbeat. Because this system is autonomic, you can consciously make it stop (hold your breath as you finish this sentence), but it will operate on its own, naturally.

The autonomic system has two major functions under its command, the sympathetic nervous system and the parasympathetic nervous system. Imagine that you are about to take a major exam. You notice that your breathing becomes a bit faster, and your heart beats quickly. This is your sympathetic nervous system kicking in. Once you realize that you are prepared, your parasympathetic nervous system will kick in, essentially doing the opposite of the sympathetic system. Your heart rate slows down!

The Central Nervous System

The brain is at the head of a super network of information, creating and controlling even the smallest bodily actions and movements.

These neural networks are the reason why, we as humans, can have much deeper thought and reasoning in comparison to other species of animals. Each time we learn something or practice something new, such as a new language, we are creating and establishing stronger connections within this network.

In the central nervous system is a smaller information highway with lots of traffic, the spinal cord. Here, there are messages of motor control, such as a reflex. A reflex is the body's automatic response to something; for example, a stimulus like heat. When you accidentally touch a hot stovetop, your body's natural response to the feeling of pain is to quickly remove your hand.

Endocrine System

Another form of information processing is done through the endocrine system of the body. This is a slower form of communication through the glands of the body, which release chemicals such as hormones that travel through our bloodstream. Hormones are the endocrine system's mail carriers (much slower than the superhighway of the neurotransmitters) that influence our needs for food and aggression. Because the endocrine system relies on the bloodstream to carry its messages, the effects can last longer (which may be why you stay angry longer because of a disagreement).

Moments of possible danger trigger the adrenal glands to release the chemicals epinephrine (you may know it by the more common term adrenaline) and norepinephrine. These chemicals are the reason for our fight-or-flight response in potentially dangerous situations.

The tiny structure of the pituitary gland is in charge of some very important events. One of its major jobs is to release the growth hormone (the reason for our physical development). Another chemical released by the pituitary glands is oxytocin. This is the chemical related to bonding and love.

"Old Brain" Structures

It can be difficult to realize, but our brain system has new portions as well as older structures. Through change and developments in humans, there have been newer functions added to the basis of fundamental brain structures that are called the "old brain".

The Brainstem

The brainstem is the oldest portion of the human brain. The lowest portion of the brainstem structure is the medulla. In the medulla are the controls for fundamental bodily functions such as our heartbeat. Above this sits the pons, which help us with coordination.

The Thalamus

Above the brainstem is the thalamus, which is in charge of the brain's sensory control. The thalamus takes information from all of our senses (except smell) and sends these messages to the higher processing portions of our brains. Because it is a two-way system, the thalamus will also receive messages from the brain involving sight and touch, etc.

The Reticular Formation

The reticular formation is the crossing guard of information that comes from the spinal cord up through the thalamus. Arousal is the main function of the reticular formation of the body.

The Cerebellum

The cerebellum is considered to be the second brain in our system. The function of nonverbal learning and memory lies in this area. Amongst these functions is the ability to distinguish time, regulate our emotions, and be able to understand different sounds. It also is in charge of our voluntary movements.

The Limbic System

The Amygdala

This almond-shaped area of the brain is in charge of our emotional responses like fear or rage. The amygdala also attaches emotions to memory, allowing it to be better remembered.

The Hypothalamus

At the center of the limbic system lies the hypothalamus. It is in charge of our feelings of hunger and sexuality and also regulates body temperature and the sleep cycle. It releases hormones. An example of an important hormone that is released in the hypothalamus is oxytocin or the love hormone. Lesions of the hypothalamus influence unconscious functions, and some motivated behaviors like combativeness and hunger. The lateral parts are involved with pleasure and rage. Lastly, the medial part is linked to aversions and displeasure.

The Cerebral Cortex

The cerebral cortex is made of two hemispheres that are covered in connecting neural cells. This area is considered the brain control center and is about 85 percent of the brain's overall weight.

Motor Functions

The cerebral cortex is responsible for behavior mechanics such as precise movements (in our fingers for example). We also now know that there is a cross-hemisphere function in the cerebral cortex. What that means is that the right side of the brain controls functions on the left side of the body, and the left side of the brain controls the right side of the body's functions.

Sensory Functions

If motor functions are the messages that are going out, where are the incoming messages processed in the cerebral cortex? The somatosensory cortex is the area that can process and understand these, as well as sensations of movement. For example, a sensitive area of the body such as the lips has a larger area devoted to it in the somatosensory cortex.

Behavior Genetics

Behavior genetics help us to explain and understand our personalities, behaviors, and individual differences in both psychological and biological terms. The biological basis for our behaviors lies in both the functions of our innermost bodily functions and, even more deeply, our genetic makeup.

Genes

If a man is a professional baseball player, does that mean that his future child will be a professional baseball player as well? This is what interests those who study nature vs. nurture in the elements of human behavior. Geneticists and psychologists both look for DNA variations that could answer questions about who we are as individuals, and if these differences explain our behaviors and choices.

Environment

We as humans have an amazing ability to adapt to our environment. Epigenetic studies try to understand molecular mechanisms and how they are affected by environmental factors. Although genes have a major effect on how we are and behave, it is understood that environmental factors can "turn them on and off". For example, stress, drugs, or our diets all can be major factors to consider.