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Physiological Psychology
Physiological psychology is branch of psychology that studies how our physiological processes contribute to our mental processes. It is a study of how neurons work and how the brain mediates our behavior. It focuses on how different parts of the brain arbitrate different behaviors. The main focus of this field of study it to show how psychological and mental representations derive from biological processes. Physiological psychology integrates the study of biology, chemistry, physics, philosophy and evolution. Scientists in this field study split brain patients and patients with a variety of brain abnormalities to see how their physiological processes affect their behaviors and mental development.

History
This subfield of psychology arose from when human beings started questioning consciousness. The question of mind-body arose amongst philosophers where they started to debate how the mind and body interact. Most of us believe that the mind is a phenomenon produced by the workings of the nervous system. We believe that once we understand the workings of the human body – in particular, the workings of the nervous system – we will be able to explain how we perceive, how we think, how we remember, and how we act. Two main philosophies contributed to this subfield of science in the 17th century. One was Dualism, which was a philosophy put forth by Renee Descartes. It is a belief that the body is a material and physical aspect, while the mind (soul) is immaterial. The soul interacts at the pineal gland, which controls our muscles. Once the soul and body interacted, it set everything in motion therefore all behavior is “reflexive”. The opposite of this theory put forth was Monism, which was the belief that the universe is only made of matter and energy. The soul/mind is also a material phenomenon where mental behavior is biological and the working of the nervous system. The mind is not spiritual.

Luigi Galvani (17th century Italian Physiologist)
Galvani was a scientist who contributed to the study of physiological psychology. He electrically stimulated frog’s nerves to make it move or twitch. Even when the nerve we detached to the body, it was still able to move. This is parallel to the philosophy of monism, that our movements are mechanistic.

Johannes Muller (19th century Physiologist)
Muller wrote the Doctrine of specific nerve energies, where he concluded that all nerve fibers carry the same message, so there must be different types of sensory information specified by particular nerve fibers that are active.

Pierre Flourens (19th century Physiologist)
He performed experimental ablation where from a damaged part of an animal brain, you infer the function of that brain by observing the behavior that the animal can no longer perform. In other words, part of the brain is surgically removed and then observe the behavior that the animal can no longer perform, from that, an assumption is made that that part of the brain is responsible for that certain behavior.

See other Contributors:
 * Charles Darwin
 * Paul Broca
 * Carl Wernicke
 * Santiago Ramon y Cajal
 * Adolphe Quetelet
 * Rudolf Hermann Lotze
 * Hermann von Helmholtz
 * Gustav Fritsch

Emotion and Facial Expressions
Many scientists started to study the origins of emotion and facial expressions. This study started from Darwin. Darwin wrote a book, The Expression of the Emotions in Man and Animals where he gathered data by observing different people from different countries. Darwin proposed a universality of emotions in the same species. There were many other scientist then contributed to the study of the universality and innate nature of emotions.

Some contributions and findings:

a.   Paul Ekman tested emotion by using Pictures of Facial Affect in 1976. He tested isolated cultures by showing individuals from the culture pictures of Caucasian actors portraying six universal emotions, happiness, sadness, fear, disgust, surprise and anger. These a.   Tomkins showed that different cultures should judge facial expressions similarly. For example if shown a picture of a happy face, two different cultures would assume it’s the emotion of happiness a.   Tested by Woodworth in 1954
 * 1.Different cultures with different languages and no contact should have similar facial expression of emotion
 * 2.Cultures should judge facial expressions similarly
 * 3.Visually impaired people from birth should have the same or similar facial expressions of emotions than sighted people.

Conclusion: Facial expressions are innate and not learned. People blind from birth show similar facial expressions just as others. When different cultures were given different scenarios, most cultures assumed it to be the same emotion. For example, if given a scenario: imagine you had a baby and it just passed way, how would feel? Most answers by different cultures were the same. The Production of Emotional Expressions is not generated in Motor Cortex. Studies were done to test if emotion is controllable and voluntary, research proves it is not involuntary and cannot be due to the motor cortex. Scientists tested:

Volitional Facial Paresis following damage to face region of motor cortex:


 * 1. This showed that people cannot voluntarily move facial muscles on affected side of face, but they can show normal involuntary facial expression of emotion. For example, when a person laughs they will show full-blown emotions despite the paralysis. This proves emotion comes from another part of the brain than the motor cortex.

Emotional Facial Paresis following damage to insular region of prefrontal cortex:

This suggests that control over muscles involved in facial expression is not under voluntary control, but also proves that sociopaths can voluntarily control these movements.
 * 1. Show no emotion on affected side of face but can voluntarily move muscles

Hemispheric Asymmetry in the recognition and expression of emotion tests that the right hemisphere of the brain is dominant in both perceiving and expressing emotions. The right hemisphere is also better at judging facial expression of emotion. If a blank screen was divided into right and left and a picture of a human face flashed quickly on both sides of the screen, we are more likely to notice the face on the left side of the screen first and notice the facial expression of that person. This proves that we are better at identifying the left side because the right hemisphere judges better.

History of Studies Examining the Role of the Amygdala in Emotion


 * 1.Brown & Schafer (1888) – Large medial temporal lobe lesions turned wild and fierce monkeys into tame, passive, indifferent monkey.


 * 2.Downer (1961) – Unilateral amygdala lesion, also lesion optic chiasm, resulting in projections from one eye to ipsilateral hemisphere only. If blocked eye projecting to intact hemisphere, animal was tame and passive. If blocked eye projecting to lesioned hemisphere, animal was wild and fierce.


 * 3.Cahill (1995) – Urbach-Weithe Disease: amygdala damage impairs ability of emotion to modulate strength of memory. Results in progressive cell death in amygdala only. People wind up having no amygdala, they appear typically normal and have low affect. In the study, subjects that were chosen were people with normal functioning amygdalas while another group had damaged their amygdalas. Both groups were told stories where the first part was dull and boring, the second part was much more emotionally arousing and the third part was boring. A week later subjects were brought back and were tested on their memory of the story. Researchers concluded that the amygdala is involved in expression and modulates the strength of other kinds of memories.

Periaqueductal Gray (PAG) and Emotions 

Overt behavioral components of emotional responses. It is involved in freezing response to fearful stimuli. Freezing behavior has an evolutionary advantage. Any suspicious or sudden movement that is threatening allows the body to freeze to evaluate the situation.

Ventral PAG is involved in predatory behavior. Electrical stimulation to this area of the brain will cause a cat to adopt predatory posture and to attack a rat. Stimulation to the VPAG of rats will cause them to rapidly learn to press a bar to turn on stimulation but not to turn it off. This is stimulating to these animals because it feels good to them.

Dorsal PAG is involved in defensive behavior. Electrical stimulation to the DPAG will cause a cat to adopt a defensive posture. Rats will rapidly learn to press a bar to turn off stimulation, but not turn it on. This is because rats do not like being in a defensive position that is threatening to them.

PAG lesions also block maternal behavior. This causes an aversive feeling in the rat. Maternal behavior is blocked which causes baby rats to become malnourished.

Learning
Pavlovian Conditioning Pavlovian conditioning is also known as classical conditioning. It is a model made by Ivan Pavlov, which describes how behavior is learned in human and animals. An unconditioned stimulus (naturally occurring factor) elicits an unconditioned response (naturally occurring), for example if a piece of food is placed on a tongue of a dog (US), the dog will salivate (UR). This stimulus and response occurs without any learning. Pavlovian conditioning assumes that learning occurs when a conditioned stimulus is paired with an unconditioned stimulus, a conditioned response occurs. For examples a conditioned stimulus is neutral such as a bell or loud horn etc. When the bell (CS) is paired with food (US), it will elicit salivation in a dog (CR).

Hebb’s Model for Acquisition of Associations Hebb’s model takes the Pavlovian conditioning into consideration by explaining what takes place in neurons while this learning is taking place. Before conditioning, the unconditioned stimulus neuron elicits a strong excitation, which causes a response (output neuron). Before conditioning, the conditioned stimulus neuron has a weak excitation, which does not have any effect on the output. The link already exists, but does not affect the output. For example, when the US neuron fires, output will generate salivation in a dog (hardwired). When the bell is detected, the CS neuron fired, it releases neurotransmitters but not enough to excite an output. There are not enough receptors on the dendrite.

After conditioning, the CS neuron fires and releases enough neurotransmitters to elicit a strong excitation just like the US neuron. Learning is associated with neural plasticity, changing is an experienced, dependent way, which is associated with the strength of connection of synapses. For example in fear conditioning, the CS neuron before conditioning (Tone) elicits a weak excitation, which is not strong enough to cause a fear response. The US neuron (Mild footshock) elicits a strong excitation, which causes a fear response. After conditioning the CS neuron (Tone) is converted to strong excitation, which causes a fear response.

Importance of NMDA receptors in Learning This receptor is associated with glutamate that binds to it, but the channel does not open because it is blocked by Mg+ ion. This will have no effect. Magnesium ion blockade drifts away only when cell is highly depolarized, as might occur when many AMPA receptors activated simultaneously. When this happens, NMDA receptor admits Ca++ into the cell, which activates a number of calcium-dependent biochemical cascades implicated in neuronal plasticity. Many forms of synaptic plasticity have been shown to be NMDA receptor-dependent, that means that if they are blocked by NMDA receptor antagonists, such as APV, learning or plasticity may not occur. Blocking NMDA receptor with APV will block the strengthening of synaptic connections. There will be little neuronal communication, but not enough.

Memory
There are two types of memory, declarative and non-declarative. Non-declarative is associated with memories of skills, habits, procedures, rules and simple conditioning. Declarative memory is associated with facts, events, and memories available for conscious reflection and spatial memory. Hippocampus is mostly involved with declarative forms of memory and these depend on MNDA-receptor-dependent plasticity.

Morris Water Maze Test of Spatial Learning

This was a test given to rats to test spatial memory learning. Rats were placed in a pool that were divided into four quadrants labeled Northwest, Northeast, Southwest, and Southeast. There was a curtain placed around the pool with spatial cues such as a star or a triangle. There was a hidden platform placed in one of the quadrants. Rats were timed to find the pool. This was used to test if rats use spatial cues to find the hidden platform.

The Morris Water Maze Learning requires the hippocampus. A rat with a leisoned hippocampus never learned to find the hidden platform, but a normal rat was able to learn where the hidden platform was placed in the pools. The normal rat got better and better each time and took less time to find the hidden platform. To known that rats were using spatial cues, the curtain was rotated each time by 90 degrees and the rat would end up at the quadrant where the spatial cues were originally placed. Once rotated, the rat would have to learn again to find the hidden platform, which would increase his time to find the hidden platform. This study shows that the hippocampus is necessary to learn spatial cues.

Another way this was tested was to use NMDA receptor Antagonism in hippocampus in the Morris Water Maze Learning Test. NMDA receptor antagonism blocks the animal’s ability to learn spatial locations. The rat that was injected with APV into the hippocampus was not able to learn spatial cues. They had the same results as the rat whose hippocampus was lesioned. Compared to this, a normal rat was able to perform well in the Morris Water Maze Test.

This study suggests that there are place cells in the hippocampus that fire action potentials only when the subject is in a specific place within a specific environment.

London Taxi Drivers (McGuire and colleagues, 2000) Taxi drivers in London are required to learn complex routes before becoming taxi drivers. When they are asked to recall easy routes, hippocampus is only moderately active. When they are asked to imagine complex, novel routes through the city, the hippocampus becomes extremely active. It was tested that London taxi drivers have larger hippocampuses than most normal people.

(HR)

Neuroplasticity
Neuroplasticity defined in the simplest way is the brain’s ability to be flexible and to rewire in response to experience. It is also a field that can be practiced in psychology and is the study of how experience and or self-directed attention can create physical, structural changes in our brains. The brain is always changing not only in function but in physical structure as well by adapting to what is happening in the environment and by shifting and directing our attention. Neuroplasticity is something that never sleeps and begins from the very moment a person is in utero.

Olfaction
Olfaction is the second chemical sense which helps us to identify food and avoid food that has been spoiled and cannot be eaten. This system helps members of many species in tracking their prey or detecting predators and in identifying friends, foes and mates. Many animals such as dogs have more sensitive olfactory systems than humans do. The olfactory system is second only to the visual system in that its number of sensory receptor cells is estimated to be around 10 million. Humans should not underestimate their olfactory system for the reason that they can smell substances at lower concentrations than even the most sensitive instrument used in laboratories could not do. One thing that makes our olfactory system different from those of other mammals is that they put their nose where odors are the strongest which would be right above the ground. Humans can smell some of the most difficult odors above the ground at five or six feet, however if you were to take a bloodhound and place him five or six feet above the ground he would not be able to smell the odor.

The Stimulus
The stimulus for odor consists of volatile substances having a molecular weight in the range of approximately 15 to 300. Almost all odorous compounds are lipid soluble and of organic origin. However, many substances that meet these criteria have no odor at all.

Anatomy of Olfactory System
The olfactory epithelium which is the mucous membrane, consists of over 6 million olfactory receptor cells. Only about 10 percent of air that enters the nostrils reaches the epithelium so just a sniff is sufficient to sweep air up into the nasal cavity so that it reaches the olfactory receptors. The olfactory receptors include bipolar neurons located in the olfactory epithelium which lines the roof of the nasal sinuses or on the bone that underlies the frontal lobes. The receptors send processes toward the surface of the mucosa, which divide into cilia. The membranes of these cilia contain receptors that detect aromatic molecules dissolved in the air that sweeps past the olfactory mucosa. The axons of the olfactory receptors pass though the perforations of the cribriform plate into the olfactory bulbs, where they form synapses in the glomeruli with the dendrites of the mitral cells. These neurons send axons through the olfactory tracts to the brain, principally to the amygdale, the piriform cortex, and the entorhinal cortex. The hippocampus, hypothalamus, and the orbitofrontal cortex receive olfactory information indirectly.

Transduction of Olfactory Information
Researchers have recognized for many years that the olfaction cilia contain receptors that are stimulated by molecules of odorants, however the receptor was unknown to them. Then in 1989, Jones and Reed found a particular G protein which is a protein that is able to activate an enzyme that catalyzes the synthesis of cyclic AMP, which could then open up sodium channels and depolarize the membrane of the olfactory cell.

(LK)