Basic Functions of Brain Structures
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- Thalamus
- In the center of the forebrain; looks like two avacados joined side by side (one in left hemi, one in right); most sensory info first goes to thalamus(except for olfactory info), which processes it and then sends to cerebral cortex
- Hypothalamus
- small area near the base of the brain just venral to the thalamus; widespread connections with rest of forebrain and the midbrain; conveys messages to the pituitary gland, altering its release of hormones; damage to hypthalamus leads to abnormalities in motivated behaviors (feeding, drinking, temp reg, sexual behavior, fighting or activity level)
- Pituitary Gland
- an endocrine gland attached to the base of the hypothalamus; synthesizes and releases hormones into the bloodstream
- Hippocampus
- large structure between the thalamus and cerebral cortex; critical for storing certain kinds of memory, such as new memories
- Pons
- lies anterior and ventral to the medulla; many nuclei for several cranial nerves; axons cross from one side of the brain to the other - this is where axons from one side of the brain cross to opp. side of spinal cord so that right hemi controls left side of body and vice versa
- Medulla
- just above the spinal cord; could be regarded as an enlarged, elaborated extension of the spinal cord; controls a number of vital relfexes - breathing, heart rate, vomiting, salivation, coughing and sneezing; damage can be fatal
- Cerebellum
- large hindbrain structure with many deep folds; control of movement, balance and coordination; shifting attention back and forth between auditory and visual stimuli; timing, including sensory timing
- Corpus callosum
- neurons in each hemisphere communicate with neurons in the corresponding part of the other hemisphere through these two bundles of axons
- spinal cord
- part of the CNS found within the spinal column; the spinal cord communicates with the sense organs and muscles below the level of the head; segemented; each segement has on eeach side both a sensory nerve and a motor nerve; gray matter in the center of the cord is densely packed with cell bodies and dendrites; many neurons of the spinal cord send axons from the gray matter toward the brain or to other parts of the spinal cord through white matter (myelinated axons)
- Cerebral cortex and the Cerebral hemispheres
- the cellular layers on the outer surface of the cerebral hemispheres form gray matter known as the cerebral cortex; large numbers of axons extend inward from the cortex, forming the white matter of the cerbal hemispheres
- Bell-Magendie Law
- the entering dorsal roots (axon bundles) carry sensory info and the exiting ventral roots carry motor info, to the muscles and glands.
- Central Nervous System
- brain and spinal cord
- Peripheral Nervous System
- the nerves outside the brain and spinal cord; two divisions-somatic nervous system and autonomic nervous system
- Somatic Nervous System
- the nerves that convey messages from the sense organs to the CNS and from the CNS to the muscles and glands
- Autonomic Nervous System
- controls the heart, the intesetines and other organs; made up of two subdivisons
- Sympathetic Nervous System
- one subdivision of the autonomic nervous system; a network of nerves that prepare the organs for vigorous activity; "fight or flight"-increase breathing, heart rate and descreae in digestion
- Parasympathetic Nervous System
- one subdivison of autonomic nervous system; faciliates vegetative nonemergency responses by the organs; descreases heart reat, breathing and increases digestion
- brainstem
- medulla and pons, the midbrain and certain structures of the forebrain
- Cranial nerves
- control sensations from the head, muscle movements in the head and much of the parasympathetic output to the organs
- tectum
- roof of midbrain; two swellings on each side of the tectum are the superior colliculus and the inferior colliculus
- tegmentum
- intermediate level of the midbrain
- limbic system
- inter-linked structures form a border around the brainstem; olfactory bulb, hypthalamus, hippocampus, amygdala, cingulate gyrus and cerebral cortex
- basal ganglia
- group of subcortical structures lateral to the thalamus
- occipital lobe
- posterior end of the cortex; vision
- parietal lobe
- monitors all info about eye, head and body positions and passes it to brain areas that control movement
- temporal lobe
- lateral portion of each hemisphere near the temples; audiory info and some of the more complex aspects of vision (recognition of faces and perception of movement); emotional and motivational behaviors
- frontal lobe
- contains the primary motor cortex and prefrontal cortex (sensory)
- Physiological
- relates the behavior to a brain structure or other organ; area of a songbird's brain grows because of testosterone ---->larger in males----->males can sing in adulthood
- Ontogenetic
- development of structure or behavior; a young bird has the genes to be predisposed to sing and learns from hearing the mature bird sing
- Evolutionary
- examines a structure or behavior in terms of evolutionary history; one bird song may closely resemeble another, suggesting they evolved from single ancestor
- Functional
- why the structure or behavior evolved as it did; only males sing during mating season, only in his territory in order to attract females....so singing has evolved to improve chances of mating
- Mind-Body Problem
- what is the relationship between mind and the brain?
- Dualism
- belief that mind and body are different kinds of substance that exist independently but somehow interact
- Monoism
- the universe consists as only one kind of existence; 3 types of monoism: materialism, mentalism and identity position
- Materialism
- everything that exists is material, or physical
- Mentalism
- the view that only the mind really exists
- Identity position
- the view that mental processes are the same thing as certain kinds of brain processes but described in different terms (the fright you feel when someone has a gun is the same thing as a certain brain pattern)
- Easy problems
- many phenomena that we call consciousness, such as the difference between wakefulness and sleep and the mechanisms that enable us to focus our attention - difficult scientifically but pose no philosophical problems
- Hard Problems
- the question of why and how any kind of brain activity is associated with consciousnes
- Solopsism
- I alone exist or I alone am conscious
- problem of the mind
- difficulty of knowing whether other people or animals have conscious experiences
- Cajal
- Golgi found that you could stain cells with silver salt while not affecting other cells, so you could look at individual cells; Cajal used this techinque to look at infant brain nerve cells (bc they were smaller and more compact so easier to look at on a single slide)This demonstarted the structure of a nerve cell and that they don't merge into each other, they're separate.
- Sherrington
- dog strapped into harness suspended above the ground; he pinched the dog's feet, the dog flexed (raised) the pinched leg and extended the others; found same movements after disconnected spinal cord from brain so suggests that spinal cord controlled the flexion and the extensions; also realized must be delay at synapses because slower than conduction along an axon (pinched dogs foot, measured time and distance it took for the reflex and calculated it was much slower than along axon); small pinches at slightly different times/locations causes stronger reflex so able to summate (quicker the pinches the stronger the reflex because the stimuli decays within half a second but can combine with another stimuli to build up-temporal summation; he pinched two different points at the same time to get a reflex-spatial summation); ;when one set of muscles becomes excited another set relaxes
- EPSP
- excitatory postsynaptic potential; graded depolarization-from sodium ions entering the cell but subthreshold and decreases as travels along membrane
- IPSP
- inhibitory postsynaptic potential; temporary hyperpolarization of a membrane
- Loewi's experiment
- repeatedly stimulated vagus nerve of a frog's heart so heart rate decreased; he collected fluid and transferred it to second frog's heart...heart rate decreased; same experiement but with increasing heart rate; so heart released somethign that inhibited heart beat and then also released something that increased heart rate...had to be chemicals...so concluded that nerves send messages by releasing chemicals
- local anesthetic
- attach to the sodium channels of the membrane, preventing sodium ions from entering so action potential blocked...anesthetics applied to sensory nerves carrying pain msgs, the msg is prevented from reaching brain
- general anesthetic
- decrease brain activity by opening certain potassium channels wider than usual...so when stimulus happens and sodium rushes in, potassium rushes out, preventing action potential
- For evolution to exist you must have...
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-variation
-heredity or replication
-differential fitness;viable offspring able to reproduce