Transcript Document
Biological Bases of Behavior The Nervous System The Hindbrain Neurons The Midbrain 2 Categories The Forebrain 3 Kinds Right/Left Hemisphere Anatomy of a neuron Plasticity in the brain Communication The Endocrine system Neurotransmitters Heredity and behavior CNS/PNS Agonist/Antagonist The Brain The Limbic system • GABA is a major inhibitory neurotransmitter in the brain. A lack of GABA can lead to involuntary motor actions, including tremors and seizures. Alcohol stimulates the release of GABA. Low levels of GABA produce anxiety, and GABA agonists (tranquilizers) are used to reduce anxiety. • Glutamate is the most common neurotransmitter, it’s released in more than 90% of the brain’s synapses. Glutamate is found in the food additive MSG…excessive glutamate can cause overstimulation, migraines and seizures. The Central and Peripheral Nervous Systems • What components make up the CNS? • The brain and spinal cord • What are the two systems that comprise the PNS? • The somatic and the autonomic • What are the two components that comprise the autonomic? • The sympathetic and the parasympathetic The Nervous System The Brain, The Hindbrain • • • • • • • • • The hindbrain is located at the skull’s rear The hindbrain is the lowest portion of the brain There are three parts of the hindbrain… The medulla Helps controls life sustaining behaviors The cerebellum Plays pivotal roles in motor coordination The pons A bridge in the hindbrain involved in sleep and arousal and also plays a role in movements of the body such as walking and balance. The Brain, The Midbrain • The midbrain is located between the hindbrain and forebrain • Nerve fibers ascend and descend to connect the higher and lower portions of the brain and contains areas that are concerned with integrating sensory processes • The midbrain contains the reticular formation • The reticular formation is a collection of neurons involved in behaviors such as walking, sleeping, sex, and reacting. The reticular formation is also responsible for filtering out stimuli that are coming into the brain from the spinal cord and to relay the remainder of the signals to other areas of the brain. • When electrical stimulation is applied to the reticular formation of an animal, the animal becomes fully awake, when severed, the animal falls into a deep coma • The midbrain also consists of small groups of neurons that use the neurotransmitters serotonin, dopamine, and norepinephrine • They send signals to a variety of brain regions and are why they are involved in higher level and integrative functions The Brain, The Forebrain • The forebrain is the largest and most complex region of the brain • What are the components that make up the forebrain? • The thalamus, the hypothalamus, the limbic system, and the cerebrum • The thalamus is referred to as the relay station and is involved in integrating and filtering information and relaying some of the remaining signals to higher brain levels • The hypothalamus is involved in the regulation of basic biological needs • The limbic system regulates emotion, especially pleasure centers and includes the thalamus, the hypothalamus, the hippocampus, and the amygdala • The cerebrum is the largest and most complex part of the human brain divided into 2 parts the left and right hemispheres The Brain The Cerebral hemisphere • The cerebral hemisphere is • divided by lobes • The occipital lobe is at the back of the head and is responsible for visual signals • The parietal lobe registers the sense of touch • The temporal lobe contains areas responsible for auditory processing and when damaged, people experience the inability to comprehend speech and language, or aphasia • Broca’s aphasia…people find it difficult or impossible to produce speech, but can comprehend speech (verbal/spoken) • Wernicke’s aphasia…people can speak, but they have difficulty finding the correct words and have difficulty comprehending written or spoken communication • Mirror neurons are neurons that are activated by performing an action or by seeing another or person perform the same action Front Part Of The brain Plasticity in the Brain • What is plasticity? • Plasticity is descriptive of the brain because of its ability to change and adapt can be functional plasticity or structural • Structural plasticity-when presented with new learning opportunities, the brain’s structure will change in an effort to adapt to the new processes… the hippocampus of New York cab drivers • Functional plasticity-when areas of the brain have sustained damage that affects incoming sensory pathways, the brain will reorganize the neural pathways, in blind people, areas in the occipital lobe will assist in verbal processing • Plasticity is limited and declines with age…“use it or lose it” Right/Left Brain • The left hemisphere of the brain controls the right side of the body and contains areas dedicated to logic, reasoning, analysis, and language • The right hemisphere controls the left side of the body and contains brain areas dedicated to emotional and creative impulses • Lateralization allows for information to be shared between the hemispheres • In split-brain surgery, the corpus callosum is cut to reduce the severity of epileptic seizures only done in cases in which the patient doesn’t respond to other treatment…split brain study The Endocrine System • • • • • • • • • • • • • • • • • • • The endocrine system consist of glands that secrete chemical messengers into the bloodstream to help control bodily functions The messengers are called hormones What are hormones? Hormones are the chemical substances released by the endocrine glands The endocrine system is controlled by the nervous system through the hypothalamus The hypothalamus works in concert with the pituitary gland The pituitary gland (master gland) releases a great variety of hormones that extend throughout the body, stimulating actions in other endocrine glands The endocrine system is involved in the fight-or-flight response Too much stress may also suppress the process of neurogenesis in the hippocampus In times of stress, the hypothalamus sends signals along two pathways… the autonomic and through the pituitary gland----adrenal glands Then the adrenal glands secrete hormones throughout the body in preparation for the emergency Too much stress can suppress the immune response system, making the person vulnerable to diseases Testosterone is a male sex hormone produced by the testes Women secrete small amounts of testosterone from the adrenal cortex There are positive correlations between testosterone levels and aggression in both men and women Testosterone levels-aggression??? Aggression-testosterone levels??? There are correlations between testosterone and cognitive abilities But for older adults, higher testosterone levels are predictive of higher scores on memory, information processing, and spatial abilities The Evolutionary Bases of Behavior • Darwin and natural selection • Adaption is an inherited characteristic, because of natural selection...it occurs slowly, gradual, lingering in a population…humans show a taste for fatty foods, but we no longer need to intake lots of calories