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Physiological psychology is a subdivision of behavioral neuroscience (biological psychology) that studies the neural mechanisms of perception and behavior through direct manipulation of the brains of nonhuman animal subjects in controlled experiments. This field of psychology takes an empirical and practical approach when studying the brain and human behavior. Most people in this field believe that the mind is a phenomenon that stems from the nervous system. By studying and gaining knowledge about the mechanisms of the nervous system, physiological psychologists can uncover many truths about human behavior.Unlike other subdivisions within biological psychology, the main focus of physiological psychological research is the development of theories that describe brain-behavior relationships.

Physiological psychology studies many topics relating to the body’s response to a behavior or activity in an organism. It concerns the brain cells, structures, components, and chemical interactions that are involved in order to produce actions. Psychologists in this field usually focus their attention to topics such as sleep, emotion, ingestion, senses, reproductive behavior, learning/memory, communication, psychopharmacology, and neurological disorders. The basis for these studies all surround themselves around the notion of how the nervous system intertwines with other systems in the body to create a specific behavior.

The nervous system
The nervous system can be viewed as the control system that is interconnected with all of the other body systems. It consists of the brain, spinal cord, and other nerve tissue throughout the body. This system is responsible for reacting to internal and external stimuli and uses electrical and chemical signals to send out responses to other parts of the body. Nerve cells, or neurons, are what collectively make up the nervous system. Their components allow for messages to be passed down from one to another until they reach their destination, such as a muscle tissue. There are two major subdivisions in the nervous system known as the central and peripheral nervous system.

The central nervous system is composed of the brain and spinal cord. The brain is the control center of the body and contains millions of neural connections. This organ is responsible for sending and receiving messages from the body and its environment. Each part of the brain is specialized for different aspects of the human being. For example, the temporal lobe has a major role in vision and audition, whereas the frontal lobe is significant for motor function and problem solving. The spinal cord is attached to the brain and serves as the main connector of nerves and the brain.

The nerve tissue that lies outside of the central nervous system is collectively known as the peripheral nervous system. This system can be further divided into the autonomic and somatic nervous system. The autonomic system can be referred to as the involuntary component that regulates bodily organs and mechanisms, such as digestion and respiration. The somatic system is responsible for relaying messages back and forth from the brain to various parts of the body, whether it is taking in sensory stimuli and sending it to the brain or sending messages from the brain in order for muscles to contract and relax.

Memory and the brain
Memory is a major area of study in physiological psychology. Throughout the process of memory, we are able to encode, organize, store, and recall information and stimuli that we encounter throughout the day. There are three types of memory: sensory, short-term, and long-term. In this same sequence, we are able to store information into our brain for long periods of time without losing that information.


 * Sensory memory is the shortest type of memory, lasting less a second and degrades even faster than that. This type of memory helps in interpreting stimuli received from our senses including our vision, audition, taste, smell, and touch. If stimuli is received from the sensory input, the information is perceived by our sensory memory. The information enters this memory automatically and does not require conscious thought.


 * Short-term memory can also be called our working memory, because it is able to remember and process information at the same time. In order for sensory memory to be converted to short-term memory, our consciousness must be activated. This type of memory is still very short, lasting up to a minute, and requires a minimal amount of information to be held in memory. For a typical human being, working memory could hold up to about seven items at one time. Our short-term memory is how we are able to read this article and remember what it was about. However, without repetition and an effort to remember the information, it will be lost from memory completely. Older information may also be displaced by newer information entering the brain.


 * Long-term memory is the last type in the sequence that stores information for long periods of time. There seems to be no set capacity for what the brain is able to store away in long-term memory. Many people wonder if information that has seemed to be “forgotten” could actually just be too difficult to retrieve from our long-term memory. In order for information to be transferred from our working memory to our LTM, rehearsal and meaningful association (both combined are referred to as consolidation) would have to be present. LTM stores information semantically, which requires there to be an association and meaningfulness to the information being stored. In terms of physiology, neural networks are altered or strengthened once a piece of information becomes a part of the long-term memory. Forgetting can occur if a network is weakened or another network overlays it.

Emotion
Emotion constitutes a major influence for determining human behaviors. It is thought that emotions are predictable and are rooted in different areas in our brains, depending on what emotion it evokes. An emotional response can be divided into three major categories including behavioral, autonomic, and hormonal. The behavioral component is explained by the muscular movements that accompany the emotion. For example, if a person is experiencing fear, a possible behavioral mechanism would be to run away from the fear factor. The autonomic aspect of an emotion provides the ability to react to the emotion. This would be the fight-or-flight response that the body automatically receives from the brain signals. Lastly, hormones released facilitate the autonomic response. For example, the autonomic response, which has sent out the fight-or-flight response, would be aided by the release of such chemicals like epinephrine in order to further increase blood flow to aid in muscular rejuvenation of oxygen and nutrients.

Emotions help people to adapt in their environment. Each emotion evokes a response in order to guide our behaviors. Without fear, a person would not recognize if they are in a dangerous situation or not. Anger leads to aggression, which is necessary in certain circumstances for survival and maintaining dominance. By being able to react appropriately in the environment, people are more likely to survive and thrive.

Our emotional moods, which can last for extensive periods of times, help establish an individual’s emotional style, which helps shape their view and response to their surroundings throughout life. Six dimensions that can be contributed to shaping a person’s character include resilience, outlook, social intuition, self-awareness, sensitivity to context, and attention. Depending on where a person is at along the spectrum of each of these dimensions can predict a person’s character and behavior mechanisms. There is a partial genetic predisposition to a person’s emotional style, however much of it can be shifted and modified by stimuli in the environment.

Sleep and its physiology
Sleep is a behavior that is provoked by the body initiating the feeling of sleepiness in order for us to rest for usually several hours at a time. During sleep, there is a reduction of awareness, responsiveness, and movement. On average, an adult human sleeps between seven to eight hours per night. There is a minute percentage that sleeps less than five to six hours, which is also a symptom of sleep deprivation, and an even smaller percentage of people who sleep more than ten hours a day. Oversleeping has been shown to have a correlation with higher mortality. There are no benefits to oversleeping and can result in sleep inertia, which is the feeling of drowsiness for a period of time after waking. There are two phases of sleep: rapid eye movement (REM) and Non-REM sleep (NREM).

REM sleep is the less restful stage in which you dream and experience muscle movements or twitches. Also during this stage in sleep, a person’s heart rate and breathing are typically irregular. Non-REM sleep, also sometimes referred to as slow-wave sleep, is associated with deep sleep. The body’s blood pressure, heart rate, and breathing are generally significantly decreased compared to an alert state. Dreaming can occur in this state; however a person is not able to remember them due to how deep in sleep they are and the inability for consolidation to occur in memory. REM cycles typically occur in 90 minute intervals and increase in length as the amount of sleep in one session progresses. In a typical night’s rest, a person will have about four to six cycles of REM and Non-REM sleep.

Sleep is important for the body in order to restore itself from the depletion of energy during wakefulness and allows for recovery since cell division occurs the fastest during the Non-REM cycle. Sleep is also important for maintaining the functioning of the immune system, as well as helping with the consolidation of information previously learned and experienced into the memory. If sleep deprived, recall of information is typically decreased. Dreams that occur during sleep have been shown to increase mental creativity and problem solving skills.

As the period of time since the last Non-REM cycle has occurred increases, the body’s drive towards sleep also increases. Physical and environmental factors can have a great influence over the body’s drive towards sleep. Mental stimulation, pain and discomfort, higher/lower than normal environmental temperatures, exercise, light exposure, noise, hunger, and overeating all result in an increase in wakefulness. On the contrary, sexual activity and some foods such as carbohydrates and dairy products promote sleep.

Careers in the field
Physiological psychology, which is alternatively referred to by many names (biological psychology, biopsychology, psychobiology, psychophysiology, cognitive neuroscience, and behavioral neuroscience), is a subfield of neuroscience. People specialized in this area devote their studies to seeking the physiology that takes place in the body corresponding with different behaviors.In the past, physiological psychologists received much of their training in psychology departments in major universities. Currently, physiological psychologists are also being trained in behavioral neuroscience or biological psychology programs that are affiliated with psychology departments, or in interdisciplinary neuroscience programs. Most physiological psychologists receive PhDs in neuroscience or a related subject and either teach and carry out research at colleges or universities, are employed for research for government laboratories or other private organizations, or are hired by pharmaceutical companies to study the effects that various drugs have on an individual’s behavior.