The Biological Basis for Behavior

The Biological Basis for Behavior

The Biological Basis for Behavior The Human Brain I. Neurons A. Three types of Neurons 1. Sensory neuron = neurons that carry incoming

information from the sense receptors to the Central Nervous System(CNS) also known as AFFERENT NEURONS. Sensory Neuron

Sensory Neuron Brain Spinal Cord Motor

Neuron 2. Motor neurons = the neurons that carry outgoing messages from the CNS to the muscles and glands. Also known as EFFERENT NEURONS. 3. Inter-neurons = CNS neurons that internally

communicate and intervene between the sensory inputs and motor outputs Diagram of a Neuron B. The structure of the Neuron 1. Dendrites = the bushy, branching extensions of a neuron that receive messages and conduct impulses forward toward the cell body. Get its

name from the Greek word for tree. 2. Axon = the extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands 3. The Soma = aka the Cell body its function is to support the cell. At the center is the nucleus 4. The myelin sheath is a layer of fatty

segmented tissue that encases the fibers of many neurons a. Enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next b. The Nodes of Ranvier = the nodes along the myelin sheath 5. The Synapse = the junction between the axon tip of the sending neuron and the dendrite

or cell body of the receiving neuron also called the synaptic gap or cleft 6. Neurotransmitters = chemical messengers that transverse the synaptic gaps between neurons. They create or inhibit the receiving neuron form generating a neural impulse The Synapse II. The Nervous System

A. The Central Nervous System 1. Also known as the CNS 2. It consist of the brain and the spinal cord 3. Cerebrospinal Fluid (CSF) is a liquid similar to blood serum found in the ventricles of the brain and in the central canal of the spinal cord B. The Peripheral Nervous System PNS 1. The sensory and motor neurons that connect the CNS to the rest of the body

2. It sends sensory input to the brain and relays commands from the brain to muscles 3. Nerves = neural cables containing many axons which connect the CNS with muscles, glands, and sense organs 4. The PNS consists of a. The Somatic System = the division of the PNS that controls the bodys skeletal muscles; AKA the skeletal nervous system

b. Autonomic System = the part of the PNS that controls the glands and the muscles of the internal organs such as the heart. Parasympathetic Nervous System = the division of the ANS that calms the body, conserving its energy Sympathetic Nervous System = the division of the ANS that arouses the body, mobilizing its energy in stressful

situations The Nervous System III. The Brain A. Tools of Discovery 1. Lesions and Accidents= a. Tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue b. Used to determine the impact on the brain functioning

2. EEG a. Electroencephalogram b. An amplified recording of the waves of electrical activity that sweep across the brains surface. These waves are measured by electrodes placed on the scalp c. Evoked potentials the

amplified tracings of the change in voltage when the subject is presented with a stimuli Advantage = non invasive and useful to identify sleep patterns and some brain damage Disadvantage = not precise 3. CT/CAT SCAN

a. Aka Computed Tomography b. A series of x-ray photos taken from different angles and combined by a computer into a composite representation of a slice through the brain or body Advantages non invasive and good for seeing damage on the brain, also more cost effective than an MRI or PET scan

Disadvantage not as clear as an MRI and doesnt show the brain at work 5. PET SCAN a. Short for Positron Emission Tomography b. A visual display of brain activity that detects where a radioactive form of glucose goes while the brain

performs a given task Advantage is that it shows areas of the brain in use by the person Disadvantages include that it doesnt clearly how structures and it is very expensive 6. MRI a. Short for Magnetic Resonance Imaging

b. A technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish between different types of soft tissue c. Allows us to see structures within the brain Advantages include that is provides the most complete picture of the

structures of the brain Disadvantages include that it doesnt show the brain at work and it is very expensive 7. FMRI a. Short for functional MRI b. Similar to the

MRI but pictures are taken less than a second apart c. These pictures reveal when things happen, how the brain changes with experience and how different areas of the brain work together

8. Pros and cons of scans in general a. Advantages = detailed knowledge, clear pictures of brain structures, some allow to see the brain at work, very precise b. Disadvantages = can be invasive, or involve use of potentially damaging x-rays or radioactive substances. Also very expensive B. The Central Core

1. The brain stem a. brainstem = the oldest part and central core of the brain b. Begins where the spinal cord swells as it enters the skull c. The brainstem is responsible for automatic survival functions d. The hindbrain is the most posterior part of the brain it includes the medulla, Pons and cerebellum 2. Medulla oblongata

a. Medulla = the base of the brainstem; b. Controls heartbeat and breathing c. It lies directly on top of the spinal cord 3. Pons lies directly above the Medulla acts as a bridge between the Medulla and the rest of the brain, as well as between the cerebral cortex and the cerebellum

4. . Reticular formation = a nerve network in the brainstem that plays an important role in controlling arousal 5. The Midbrain located between the hindbrain and forebrain, it controls and coordinates some basic sensory and muscle movements. 6. The Thalamus a. The thalamus = the brains sensory switchboard

b. Located on top of the brainstem; located in both hemispheres resembling twin avocados c. It directs messages to the sensory receiving areas of the cortex and transmits replies to the cerebellum and medulla 7. Cerebellum a. The little brain attached to the rear of the brain stem, to the side of the pons and medulla b. It helps to coordinate voluntary movement and

balance D. The Limbic System 1. Sometimes referred to as the forebrain 2. The limbic system = a. a doughnut shaped system of neural structures at the border of the brainstem and the cerebra hemispheres

b. Associated with emotions such as fear and aggression and drives such as those for food and sex c. Includes the hippocampus, the amygdala, and the hypothalamus 2. The amygdale = Two almond shaped neural clusters that are components of the limbic

system and are linked to emotion 3. The Hippocampus = a. From the Latin word meaning seahorse b. Lies between the thalamus and the cerebral cortex .c Is linked with forming new memories 4. The Hypothalamus a. A neural structure lying below (hypo) the thalamus.

b. It directs several maintenance activities (eating, drinking and body temp), it helps govern the endocrine system via the pituitary gland and it is linked to emotion IV. The Cerebral Cortex A. General Description 1. The convoluted portion of our brain where thinking, memories and our personality are located.

2. Physical description a. Convolutions increase the surface area of the brain b. Gyri = rolls that form the folding out portion of the cerebral cortex VII. The Cerebral Cortex c. Sulci = valleys that form from the folding in portions of the cerebral cortex.

d. Fissures are deeper than valleys B. The four lobes 1. Frontal lobes a. The portion of the cerebral cortex lying just behind the forehead; b. Involved in speaking and muscle movements and in making plans and judgments c. prefrontal cortex receives sensory information from all senses

2. Occipital lobes The portion of the cerebral cortex lying at the back of the head; Includes the visual areas, (V1 & V2) which receive visual information from the opposite visual field cortical blindness is a specific type of blindness due to brain damage 3. Parietal lobes

a. The portion of the cerebral cortex lying at the top of the head and toward the rear; b. Includes the sensory cortex which specializes in processing body information such as touch and body location 4. Temporal lobes a. The portion of the cerebral cortex lying roughly above the ears; b. Includes the auditory areas, each of which

receives auditory information primarily from the opposite ear. c. One of the key areas of speech known as Wernickes Area is located in this lobe C. The motor cortex = an area at the rear of the frontal lobes that controls voluntary movement D. The sensory cortex = the area at the

front of the parietal lobes that registers and processes body sensations Motor and Sensory Areas E. Association areas = areas of the cerebral cortex that are not involved in primary motor or sensory functions. They are involved in higher mental functions such as learning remembering, thinking and speaking.

V. Sleep and Dreams A. Biological Rhythms 1. Biological Rhythms = patterns associated with our biological clock. These patterns can span days, hours or even minutes. 2. Circadian Rhythms = Biological cycles that occur about every 24 hours. For example or sleep, blood pressure, body temperature and urine production

B. How is our sleep cycle controlled 1. The suprachiasmatic nucleus (SCN)lies in the hypothalamus and is the bodys main biological clock. 2. When light hits the retina it sends a signal to the SCN which then relays a message to the pineal glands which in turn secrete melatonin which is a hormone that plays a key role in regulating sleep

3. Brain structures associated with sleep a. The superchiasmatic nucleus influences the entire sleep cycle. In rats with damage to this structure they will still sleep the same number of hours but the length and frequency of the their sleep episodes will be disrupted. It uses specialized optic receptors to pick up light. This is why it is important to turn off all lights including the tv, computer and phone in your room. b. The pineal gland also plays an important role in that it controls production of melatonin an important sleep hormone. The pineal gland is stimulated to produce melatonin in the dark and stimulated

to cease production when in the light 4. Sleep studies a. The Siffre Cave Study - -French cave explorer Michael Siffre spent 6 months in a cave without any external cues to set his biological clock. Sleep patterns were erratic at first but settled into a 25 hour cycle. b. Sleep research on teens indicates that pineal gland does not turn on production of melatonin

until later in the day for teens. Thus teens tend to stay up later and have trouble waking early. c. Teens NEED at least 8 hours to 9 hours or more of sleep a day. How many do you get? 4. Brain waves accompanying sleep and wake cycles. a. Every 90 minutes are so we cycle through all the sleep

stages b. Alpha waves = awake and resting c. Beta waves = awake and working d. Theta waves = drowsy e. Delta waves = two different types, one accompanying dreaming the other deep sleep without dreams

5. Sleep Stages a. Stage 1 last about 5 minutes maybe accompanied by hallucinations which are false sensory experiences, and sudden jerks of the body often referred to as a hypnogogic state b. Stage 2 Last about 20 minutes characterized by sleep spindles also known as K-Complex activity brain waves that show sharp increases in brain activity. Sometimes accompanied by sleep-talking

c. Stage 3 is a transitional stage where your brain waves begin to slow into what is known as Delta Waves. d. Stage 4 is the deepest stage of sleep last about 30 minutes and is often the period of sleepwalking or somnambulism, and bed wetting. During this stage we can actually be aware of certain stimuli such as the sound of our baby crying. e. Finally you move back through stage 3 and stage

2 into a state known as REM Sleep 6. REM Sleep a. This is your dream time lasting about 10 minutes at a stretch. b. Characterized by increased heart rate and complete muscle relaxation. c. For this reason REM sleep is often called paradoxical sleep.

d. During this stage both the male and the female genitalia become aroused even if the nature of the dream is not sexual. e. As the night progress you spend more and more time in dream sleep (about 100 minutes) a night C. Why do we sleep? 1. Studies on Sleep Deprivation a. In various animal studies including those on both cats and rats, long term sleep deprivation

resulted in death. b. Studies on humans show many effects such as difficulty concentrating, more accidents and even a weakened immune system. Periods of sleep deprivation in humans are often followed by REM Rebound where the participant spends more time in REM sleep. 2. Theories on why we sleep

a. Restoration Theory to restore the bodys energy systems, repair muscles and cells as well as to allow for growth. Evidence for Longer sleep usually occurs after large amounts of physical exercise and growth hormones are released during sleep. Evidence against Sleep duration is not reduced with lack of exercise and sleep deprivation does not produce significantly adverse effects in humans.

b. Memory Consolidation Theory = Sleep, especially REM sleep allows for memories to be consolidated. Evidence for suggest that subjects given information prior to sleep who are deprived of REM sleep remember less than those who go through normal sleep cycles. There is little evidence against this theory, however memory consolidation can occur without sleep D. Dreams

1. Dreams are a sequence of images, emotions and thoughts passing through the sleeping persons mind. 2. Dreams are notable for their hallucinatory imagery, discontinuities and incongruities and the dreamers delusional acceptance of the content and later difficulties in remembering it. 3. Freudian Theory of Dreams(Wish Fulfillment)

a. Freud believed the dreams reflected unconscious wishes that were too harmful to our psyche to be dealt with by the conscious self. b. Manifest Content = according to Freud the remembered story line of a dream c. Latent Content =

according to Freud the underlying meaning of a dream 4. Activation-synthesis model a. Proposed by Hobson and McCarley in 1977 it is a biological theory of dreams b. It hypothesizes that dreams are random firings of the brain that your brain tries to make sense of by creating a story essential dreams are just random

misfiring of the brain c. This theory has some biological support as it explains how the content of dreams could be influenced by particular areas of brain activation, such as when external stimuli get worked into your dreams. VI. Theories of Emotion A. Emotion = A response of the whole organism, involving (1) physiological

arousal, (2) expressive behaviors, and (3) conscious experience B. The James-Lange and Cannon-Bard theories 1. James-Lange theory states that our experience of emotion is our awareness of our physiological responses to emotion-arousing stimuli 2. Study done by Hohmanna. Interviewed 25 soldiers who suffered injuries to the spinal cord

b. Those who suffered injuries that left them paralyzed from the neck down responded that their emotions were much less intense c. Seemingly supports the James-Lange Theory 3. Cannon-Bard Theory = the theory that an emotion arousing stimulus simultaneously triggers (1) physiological responses and (2) the subjective experiences of emotion

C. Cognition and Emotion 1. Schacters Two-Factor Theory of Emotion a. Two factor theory = the theory that to experience emotion one must (1) be physically aroused and (2) cognitively label the arousal VII. Expressing Emotion A. Nonverbal Communication 1. In a study by Rosenthal and Hall they showed film clips of an emotionally expressive women. They found

that some people are better at reading emotions in others. They found introverts tend read others better while extroverts are easier to read. 2. Gender and Nonverbal Behavior a. Surveys reveal that women are much more empathetic than males, however when monitored electronically the gap between men and women is much smaller. b. Coats and Feldman demonstrated that women are

also more expressive of their emotions. B. Detecting and Computing Emotion 1. Ekman and OSullivan on detecting lies a. Some students watched nature films while others watched a gruesome film Detecting Emotion Test 1 b. All of the students were asked to talk about the

movie as if they were watching a nature film (in other words they were to lie.) c. They found that people are not very good lie detectors. They tried, students, psychiatrist, judges and police officers. They all performed at the level of chance. Only Secret Service Agents performed better. 2. In a follow-up study Ekman found that Government Agents (CIA), trained psychologist

and special trained street smart interrogators from LA were able to detect liars. C. Culture and Emotional Expression 1. The Ekman and Friesen study on Emotional Expression studied people from around the world and their ability to identify emotions through facial expressions across cultures. They found that this ability seemed to transcend culture. 2. One other study on blind and deaf children showed

they made the same facial expressions as we all do. This shows the universality of emotional expression because it would have been impossible for them to have learned to express emotions in this way. 3. Charles Darwin points to the adaptive purpose of reading emotions. It was probably important to our survival to read the emotions of others. We would want to stay away from angry people and move closer to people who are attracted to us.

4. Display Rules = learned ways of controlling displays of emotion in social settings. D. The Effects of Facial Expressions 1. The study done by Laird found that when people are forced to smile they feel happy, when they scowl they feel angry and when (facial feedback hypothesis) V. The Sense of Smell A. Smell or OLFACTION

1. Like taste smell is a chemical sense 2. We have over 350 types of olfactory receptor cells each of which picks up a different chemical compositions which equates to the over 10,000 various odors we can detect. 3. 1% of our genes are used to develop the many

different smell receptors in our nose 4. Path of odor Enters the nose and is picked up by receptor cells located on the surface of the nasal passage on the olfactory membrane Olfactory receptors send electric signals to the

OLFACTORY BULB The olfactory bulb then relays the information to the OLFACTORY NERVE which in turn sends the information to the brain.

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