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139 Cards in this Set
- Front
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What is the CNS?
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Central Nervous system-everything inside the skull and spinal cord
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What is the PNS?
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Peripheral nervous system-outside the brain and spinal cord. Nerves, muscles, etc
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What are the 2 major PNS divisions?
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Somatic nervous system-sensory input and voluntary motor control
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Autonomic nervous system-mostly involuntary motor control (organs & glands)
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What are the 2 divisions of the autonomic nervous system?
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Sympathetic-prepares body for action by increasing heart rate, blood pressure, etc. (emergency system-fight or flight)
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Parasympathetic-non-emergency; digestive-rest & digest
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Sterotaxis atlas
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3-dimensional guide used to locate any given structure relative to the landmark
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Coronal (frontal; transverse)
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plane shows brain structure in sections as seen from the front or rear
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Sagittal
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plane shows brain structures in sections as seen from the side.
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Horizontal
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plane shows brain structures in sections as seen from above or below.
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Medial
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toward the midline of the body, away from the side
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Lateral
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toward the side, away from the midline
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Proximal
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near to a structure
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Distal
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far or further away from a structure
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Blood brain barrier (BBB)
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protects brain from many chemicals and toxins
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3 insulating tissue layers are called
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meninges
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Name and describe the meninge layers
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dura-tough outer layer
Arachnoid-middle layer Pia-thin layer with capillary blood supply attached to brain surface |
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Cerebal Spinal Fluid
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made in choriod plexus (cells found in 4 cerebral ventricles), similar to blood plasma
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Ventricles (Ventricular system)
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1. lateral ventricles (left & right)
2. third ventricle 3. fourth ventricle 4. central canal-filled with CSF descends down center of spinal cord |
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Functions of (CSF) Cerebral Spinal Fluid
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maintain proper balance of electrolytes, nutrients, & intracranial pressure. acts like a shock absorber in some areas. flows through spaces between meninges & brain-(mainly between arachnoid & pia layers.). There is a partial barrier between CSF & brain tissue, somewhat similar to the BBB
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12 Cranial Nerves
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provide sensory, motor, output, or both
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Spinal Cord
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Part of CNS located in spinal column, communication between CNS & most of the body.
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Grey Matter
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lies in center of spinal cord, packed with cell bodies & dendrites
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White Matter
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lies in periphery of spinal cord, comprised mainly of myelinated axons
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Each Spinal cord segment
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receives motor commands from the brain that are sent to muscles & glands. receives sensory information from the body & sends most of that sensory info to the brain.
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Bell-Magendie Law
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communication between spinal cord & body is organized according to:
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Dorsal root (back)
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afferent (input)
enters the spinal cord carrying information from sensory organs |
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Ventral Root (front)
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efferent (output), mostly motor, exits spinal cord carrying info to & from muscles & glands
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Spinal cord has 31 pairs of nerves
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Cervical-8
Thoracic-12 Lumbar-5 Sacral-5 Coccygeal-1 |
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Sympathetic nervous system
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fight or flight system (action), ganglie are near spinal cord & are closely linked, neurotransmitter is mainly norepinephrine; only a few use acetylcholine
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Parasympathetic nervous system
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relaxation & digestion, constis mainly of cranial nerves from sacral region; ganglia locatied close to target organs, neurons use acetylcholine as neurotransmitter.
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Major divsions of the brain
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hindbrain, midbrain, forebrain
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Hindbrain
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most posterior, oldest part-evolutionarily similar across species. 2 divisions: cerebellum, pons & medulla
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Pons (bridge)
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involved in arousal & sleep patterns,
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Cerebellum (little brain)
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organizes sensory info that guide movement, fine tunes motor commands, smooth coordinated movements & posture control, timing functions
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Medulla Oblongata
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controls basic bodily functions-HR, breathing, BP, damage or drugs can be life threatening,
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Reticular Formation (net like)
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system that runs from medulla thru pons up to the forebrain, controls all levels of sleep & wakefullness-arousal
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Locus coeruleus-norepinephrine cell bodies; control rapid eye movement sleep.
Raphe nucleus-serotin cell bodies, control slow wave sleep. All sensory input to brain sends info here; important target for drug that alter sleep & arousal |
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Midbrain (middle) central portion, 2 major divisions-tegemental, tectum
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Tectum (roof, dorsal part)-superior colliculi-controls eye movement, reflexive blinking, pupil size.
Inferior colliculi-auditory reflexes, adjusting ear direction & orientation towards sounds |
Tegementum (under, ventral to tectum) includes; Substantia nigra-dopamine cell bodies, axons projecto to striatum/caudate which controls movement.
Ventral temental area-dopamine cell bodies, axons project to nucleu accumbens, medial frontal cortex-involved in motivation & reward Red nucleus-communicates with cerebellum involved in posture control |
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Forebrain
Hypothalamus, Thalamus, Basal Ganglia, Basal Forebrain:Hippocampus, limbic system-amygdala, septum, hippocampus, cingulate gyrus, olfactory bulb |
Hypothalmus-control ANS, regulates most biological drives, monitor nutrients, body fluid levels, blood hormones, controls pituitary (master gland), involved in agression, emotion, sexual behavior
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Thalmus-sensory relay station=eyes, ears, touch, taste; receive sensory input then send to region of cortex, integrate sensory info w/emotion & memory; drug effects here alter awareness & perception of sensory stimuli
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Basal Ganglia
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control motor movement, deterioration involved in Parkinson & Huntington; includes Caudate (striatum), Putamen, Globus pallidus
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Basal Forebrain
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several structures taht lie on dorsal surface of forebrain, contain nucleus basalis; receives input from hypothalamus & basal ganglie; send axons that release acetylcholine to cerebal cortex; part of brains system for arousal, wakefullness & attention
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Hippocampus (sea horse)
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large, located between thalamus & cerebral cortex toward posterior of forebrain; critical for storing certain types of memory
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Limbic System
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interlinked sturctures that form a border around brainstem: includes olfactory bulb, hypothalamus, hippocampus, amygdala, & cingulate gyrus of cerebral cortex
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amygdala (little almonds)-fear & aggression, taste, order & other sensory inputs
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Septum
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agression, affective tone
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Hippocampus-memory; emotional tone
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Cingulate gyrus
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fear & aggression
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Olfactory bulb
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mediates smell, has connections to areas that interpret importance of odor,
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Cerebral Cortex
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cellular layers on outer surface of cerebral hemispheres-2 halves, joined by 2 axon bundles-corpus callosum & anterior commisure, highly developed in humans than other species
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Organization of Cerebral Cortex
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6 distinct laminae (layers), many neurons arranged in columns perpendicular to laminae, cells within a given column have similar properties.
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4 main lobes of cerbral cortex bordered by landmarks: Sulci-deep grooves. Gyrus-hills or bumps
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Frontal lobe
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newest part of cortex, anterior to central sulcus
Prefontal cortex:most anterior portion of frontal lobe, receives integrated info from sensory systems, involved in cognition, learning, planning. |
contains precentral gyrus-primary motor area, controls body movement,
Prefrontal lobotomy: disconnection prefrontal cortex from brain to control psychological disorders like impulsivity & aggression-leads to emotional blandness & lack of planning. |
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Parietal lobe
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between occipital lobe & central sulcus; postcentral gyrus or primary somatosenory cortex, processes body sensations & info from muscle stretch & joint receptors, ie skin, touch sensations
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Occipital lobe
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posterior portion of cerbral cortex; primary visual cortex (striate cortex) part of system mediating visual capabilities, damage to area causes "cortical blindness"
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Temporal lobe
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located laterally in each hemisphere near temples; primary projection area for auditory info, also some visual functions (visual memoreis-discrimination) some emotion & behavior, language comprehension in left lobe for most humans (Wernicke's area); damage results in Kluver-Bucy syndrome-failure to show normal fear, anxiety & agressiveness
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Methods & Strategies of Research
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correlating brain acitivity with behavior: (phrenology, CT scans, MRI)
Record brain activity during behavior: (electrophysiological EEG, chemical PET scans, fMRI) |
Examine effects of brain damage: (autopsy, animal lesions)
Examine effects of stimulating a brain area: magnetic stimulation or electrodes. |
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Stereotaxic instrument
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holds head rigid, has calibrated moveable arm for precise placement in 3 dimensions; a coordinate system from a stereotaxic atlas-allows precise placement for manipulation of deep brain structures.
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Markers on skull surface (bregma) provide reference points: anterior-posterior, dorsal-ventral, medial-lateral
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Stimulating/manipulating neuronal activity
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techniques that stimulate/manipulate a specific brain site should logically cause a change in the behavior mediated by a particular brain area. Stimulation-increases in some behaviors. Damage (lesions)-impairs certain behaviors
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Microinjection technques-stereotaxic placement of injection cannula to adminster small quanities of drug on specific brain areas w/out chemical affecting other areas of brain.
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Electrical brain stimulation
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in animals:implanted electrodes: apply brief-low levels of stimulation to specific site, net effect is to activate surrounding neurons.
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humans: accomplished by applying magnetic fields to scalp (brief, low intensity pulse)
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Brain damage effects on behavior
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1)describe brain damage after an accident or stroke, examine damage thru brain scans-CT, MRI, or post mortem; correlate brain damage with observed deficits in behavior or other changes.
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2)cause intentional damage in animals by experimental destruction or lesions of specific brain areas.
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Effects of Brain Damage
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Paul Broca-damage left frontal hemisphere associated with loss of ability to speak.
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Probelms with studying brain damage
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humans:lack of control over what area is damaged since no 2 people have exactly the same type of damage
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animals:hard to specify exactly how behavior has changed after the damage & what connections may be interrupted.
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Experimental ablation
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removal of brain area to infer funtion of ablated area by observing deficits in behavior
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surgical removal or aspiration; typical used for an exposed surface-cortex
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Experimental lesion (destruction)
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infer the function of the area in control of behavior after destruction.
Permanent techniques: electrolytic, radio frequency, chemical (neurotoxic), knife cuts (prefrontal lobotomy)-severe connections between brain areas |
Temporary techniques: KCL, Cholchicine-slows axoplasmic transport of NT, Cryogenic cooling-cold probes chill surrounding tissue.
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Cautions interpreting lesion studies
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Generally no signle brain region exclusively mediates a behavior, there are many interconnected areas, may damage unintended areas; Sham lesions are an important control manipulation; damage must be confirmed by histology.
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Localizing neuronal activation techniques
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2-DG (deoxyglucose)-non metabolizable form of glucose radiolabeled to allow imaging of neuronal activity in brain & neural tissue
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c-Fos expression-a protein that is produced in the nucleus of neurons in response to stimulation-usually from incoming neuronal synapses
Receptor Binding (grind&bind)-radio labeled ligands to measure in vitro receptor binding, can assess receptor affinity |
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Autoradiography
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uses radiolabeled ligands to measure in vitro receptor binding; usually in slices of tissue; allows a picture of regional densities of receptors
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Uptake assays-uses radiolabled tracer molecules to measure NT uptake sites
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Immunocytochemistry
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uses immune reactions to target particular neurochemicals with antibodies; measures static regional levels of NT in brain tissue
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Microdialysis-measures levels of released NT
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Imaging techniques
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CT or CAT scan-computer enhanced analysis of scanning X-rays; 2-D slices thru brain
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MRI-better resolution than CT, relies on computer analysis of radio waves interacting with a strong magnetic field.
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PET scan (positron emission tomography)
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uses radio-labeld chemical tracer thats injected, detectors map area of brain with highest level of radioactivity, can be used to measure brain activity or binding of a drugto different brain areas.
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(fMRI) Functional MRI
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measures regional brain metabolism; can give a picture of regional brain activity during specific ongoing behavioral tasks.
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Brain size & intelligence
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moderate correlation betwen IQ & brain size (.3), amount of grey matter may also play a role, IQ is correlated with amount of grey matter.
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BUT: Men have larger brains then women but IQ is same; Elephants brains are 4x our size, Chihuahuas have highest brain to body ratio, Squirrel monkey have higher brain to body ratio than humans; common tropical aquarium fish has a higher ratio than humans
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Brain Development
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nervous system begins to form when embryo is approx 2 weeks old
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dorsal surface thickens forming neural tube surrounding a fluid filled cavity; forward end enlarges & differentiates into hindbrain, midbrain, forebrain; rest of neural tube becomes spinal cord.
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Average brain size
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birth 350 grams-by 1yr 1000 grams
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average adult 1200-1400 grams
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5 steps of neural development
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Proliferation-production of new cells along ventricles of brain divide to become glia & neurons.
Migration-movement of primitive neurons toward final destination in brain:chemicals, immunoglobins & chemokines guide new cells to their eventual destination in the brain |
Differentiation-neurons develop into axons & dendrites.
Myelination-glia cells produce myelin sheath around axons for rapid transmission of AP, 1st in spinal cord b4 forming in brain, begins in prenatal period & continues into adulthood. Synaptogenesis-formation of synapses is last step in neural development & continues thru life. |
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Original belief was NO new neurons were formed after early development BUT new research indicates otherwise.
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Stem cells-undifferentiated cells found in interior of brain, generate daugher cells which can transform glia into neurons.
Olfactory receptor cells-new ones continually replace dying ones |
Songbirds-replacement of new neurons in singing area of brain.
Adult hippocampus-stem cells differentiate into new neurons & facilitate learning-axons travel great distances across brain to form correct connections. . |
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Competition amoung axons & synapses
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postsynaptic cells strengthen synapses of some axons & weaken others
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Neural Darwinism-a selection process keeps some synapses & rejects others
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Neurotrophins (factors)
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chemical that promote the survival & activity of neurons
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Nerve growth facotr (NGF)
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in PNS. axons from ganglie that synapse with muscles survive if receive enough NGF; otherwise degenerate and die
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Brain derived neurotrophic factor (BDNF)
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in brain, promotes survival & activity of neurons.
axons that aren't exposed to neurotrophins after making connections undergo APOPTOSIS-preprogrammed mechanism of cell death. |
healthy adult nervous system conetains no neurons that failed to make appropriate connections.
After maturity apoptotic process becomes dormant & brain neurons don't need neurotrophins to survice, however neurtrophins increase branching of axons & dendrites thruout life; deficiences of neurotrophins lead to cortical shrinking & are linked to several brain diseases. |
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(FAS) Fetal Alcohol Syndrome
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excessive alcohol expsure during pregancy, particularly 3rd trimester
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symptoms: decreased alertness, hyperactivity, facial abnormalities, mental retardation, motor problems, & heart defects.
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Prenatal exposure to cocaine
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can lead to slight decreases in IQ & somewhat greater decreases in language skills
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Chronic stress 2 mom: can cause academic & social problems for offspring
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Differentiation of the cortex
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ability to fine-tune, change & adapt thru experience.
Environmental enrichment leads to: thicker cortex, increased dendritic branching, improved performance on learning tasks. |
Some benefit maybe due to physical activity; thickness declines in old age but much less in those that are physically active.
People blind from birth are better at discriminating between objects by touch; have increased activation in their visual cortex while performing this task-area normally devoted to vision now receuited for sense of touch |
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Extensive practice of a particular skill
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musicians: larger auditory cortex response to pure tones; planum temporale structure 30% larger in left temporal lobe
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Violin players have a larger area devote to the left fingers in the somatosensory cortex than nonmuscians.
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Plasticity after brain damage
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survivors show subtle 2 significant behavoral recovery.
some of the mechanisms of recovery include those similar to mechanisms of brain development such as new branching of axons & dendrites. |
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Brain trauma
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includes insults to head that break or puncture skull & directly impact brain tissue
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Closed head injury
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caused by sharp blows to the head that dont puncture the skull & brain, but cause brain damage to impact the inside of the skull
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Stroke or cerebrovascular accident (CVA)
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most common cause of human brain damage in adults. leading cause of long-term disability; symptoms depend on area of brain affected.
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common symptoms: numbness or weakness of face, arm, leg, especially one side of body.
trouble seeing in one or both eyes, difficulty walking, dizziness, loss of balanace/coordination, severe headache with on known cause, confusion, trouble speaking or understanding, unexplained dellusions or hallucinations, appreciable memory loss or cognitive deficits. |
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2 types of strokes
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Ischemia-obstructive; most common, loss of blood flow due to arterial blockage, sufficient duration causes cell death due to lack of oxygen & nutrients, especially glucose.
Thrombus-blood clot. Embolus-obstructive blood clot |
Hemorrhage-less common; caused by bleeding due to a rupture in artery; floods surrounding area with blood, excess oxygen, glucose, calcium, impairs neuronal functioning & causes death, excess ions toxic to neurons by disrupting ionic balance across cell membrane
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Edema
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accumulation of fluid in brain resulting in increased pressure on the brain increasing probability of further strokes.
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disruption of sodium potassium pumps lead to increase of potassium ions inside neurons. Edema triggers release of excitatory NT glutamate which leads to overstimulation of neuron-excess NA & other ions entering neuron in eccessive amounts. Excess +ions block metabolism in mitochondria & kill neuron
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Gliosis
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as neurons die; glia cells proliferate to remove waste products & dead neurons
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Assessment & diagnosis of brain damage: via neurological/neuropsychological tests for:
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deficits, sensory, language, memory, tests of logic & cognitive abilities, IQ test, emotional tone & responsiveness, appraisal of motivation: judged relative tto available information before damage
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Blood flow tests may include
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ultrasound-probe placed over suspected artery is determined by ultrasound generated images.
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angiography-dyes injected into blood vessels & imaged with X-ray
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Drugs & other therapy
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(tPA) Tissue plasma activator-breaks up blood clots & can reduce effects of ischemic stroke
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research has begun to attempt to save cells in the PENUMBRA region or region that surrounds the immediate damage by: blocking glutamate synapses & opening potassium channels
Cooling the brain: most effective used to minimize damage; mechanisms uncertain but is useful in first 3 days. |
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Cannabanoids
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minimize cell lose after stroke, closed head injury or other brain damage, benefits likely due to antioxidant or anti-inflammatory actions
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Omega 3 fatty acids-major component of cell membrane, may help block apoptosis & other neural damage.
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Diaschisis
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Neural death; decreased activity in surviving neurons in damaged area due to death of neurons that previously synapsed with surviving neurons.
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Receptor supersensitivity (denervation supersensativity)
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occurs under conditions of reduced synaptic input due to damage to presynaptic axons or lack of use.
increas in number or response of the postsynpatic receptors. |
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Collateral sprouting
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surving neurons, often new branching of axons form new synapses or perhaps attach to synapses taht were vacated whenanotehr neuron was destroyed.
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Reorganization
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systems in brain may reorganize & spared systems may compensate for deficits in damaged systems; age of patient influence recovery
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Kenard principle: recovery that occurs earlier in life is more likely than recovery from damage later in life.
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New Neurosurgical/neurobiological techniques
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brain grafts of healthy neurons from a donor, graft neuronal tissue taken from another tissue of the same patient, implanting neurons grown in vitro, impanting cells that can differentiate into neurons (stem cells)
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Electromagnetic Spectrum
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Visible light 380-760 nanometers in wavelength
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Electromagnetic Spectrum
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Visible light 380-760 nanometers in wavelength
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Cornea
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protective layer of eye
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Cornea
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protective layer of eye
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Pupil
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opening in the center of eye
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Pupil
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opening in the center of eye
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Iris
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colored portion of eye
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Iris
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colored portion of eye
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Lens
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focuses light on the retina
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light rays are inverted after entering the eye; light from the left side of eye strikes the right side of the retina; light from below strike top 1/2 of retina
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Lens
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focuses light on the retina
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light rays are inverted after entering the eye; light from the left side of eye strikes the right side of the retina; light from below strike top 1/2 of retina
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Accomodation
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process of lens changing shape to focus objects (light) on the fovea
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Accomodation
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process of lens changing shape to focus objects (light) on the fovea
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Retina
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contains sensing cells; cells that transducen(sensations into action potentials) light into bioelectric signals; is the rear surface of eye & is lined with visual receptors
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made of 3 layers of cellsat the back of eye.
divided into 3 primary layers with 6 different cell types. |
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Electromagnetic Spectrum
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Visible light 380-760 nanometers in wavelength
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Retina
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contains sensing cells; cells that transducen(sensations into action potentials) light into bioelectric signals; is the rear surface of eye & is lined with visual receptors
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made of 3 layers of cellsat the back of eye.
divided into 3 primary layers with 6 different cell types. |
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Fovea
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center or focal point of the retina, specialized for detailed vision; greatest visual acuity (ability to resolve spatial detail)
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Cornea
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protective layer of eye
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Fovea
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center or focal point of the retina, specialized for detailed vision; greatest visual acuity (ability to resolve spatial detail)
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Rods
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receptor cell that contains photopigments; transduces visble light into black & white (doesn't detect color); more sensative to low levels of light than cones thus important for night vision; located in periphery of retina away from fovea; acuity(spacial detail) is poor relative to cones
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Rods
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receptor cell that contains photopigments; transduces visble light into black & white (doesn't detect color); more sensative to low levels of light than cones thus important for night vision; located in periphery of retina away from fovea; acuity(spacial detail) is poor relative to cones
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Pupil
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opening in the center of eye
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Cones
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receptor cell that contains photopigments; transduce light according to frequency of electromagnetic wave & distinguishes color; 3 types-each sensative to 1 of 3 wavelengths (blue, red, green); highest cluster is at fovea-only cones here & most visual acuity
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Cones
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receptor cell that contains photopigments; transduce light according to frequency of electromagnetic wave & distinguishes color; 3 types-each sensative to 1 of 3 wavelengths (blue, red, green); highest cluster is at fovea-only cones here & most visual acuity
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Iris
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colored portion of eye
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Lens
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focuses light on the retina
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light rays are inverted after entering the eye; light from the left side of eye strikes the right side of the retina; light from below strike top 1/2 of retina
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Accomodation
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process of lens changing shape to focus objects (light) on the fovea
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Retina
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contains sensing cells; cells that transducen(sensations into action potentials) light into bioelectric signals; is the rear surface of eye & is lined with visual receptors
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made of 3 layers of cellsat the back of eye.
divided into 3 primary layers with 6 different cell types. |
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Fovea
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center or focal point of the retina, specialized for detailed vision; greatest visual acuity (ability to resolve spatial detail)
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Rods
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receptor cell that contains photopigments; transduces visble light into black & white (doesn't detect color); more sensative to low levels of light than cones thus important for night vision; located in periphery of retina away from fovea; acuity(spacial detail) is poor relative to cones
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Cones
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receptor cell that contains photopigments; transduce light according to frequency of electromagnetic wave & distinguishes color; 3 types-each sensative to 1 of 3 wavelengths (blue, red, green); highest cluster is at fovea-only cones here & most visual acuity
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Bipolar layer
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primary synapse (main connections); middle layer of retina which connects photoreceptors to ganglion cells; transmits transduced information about light between photoreceptive cell and ganglion layer
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Amacrine & Horizonal cells
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transmit info parallel to retina surface.
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Ganglion layer
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receives info from biopolar cell; axons join at point on retina called the optic disk to form optic nerve; optic disk also called blind spot since no photoreceptors exist at this point in the retina.
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Photopigments
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chemicals contained by both rods & cones that release energy when struck by light. Consist of 11-cis-retinal bound to proteins called opsins
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Steps in transduction of light energy (11)
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1. light converts quickly to all-trans retinal.
2. light is absorbed & energy is released that acitivates 2nd messengers within the cell. 3. causing hyperpolarization in photoreceptors |
4. less inhibitory transmitter is release.
5. which depolarizes bipolar cell. 6. thus, more excitatory NT is released at ganglion cells synapse-increase rate of AP in ganglion cells. |
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Color Vision
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perception of cllor is dependent on wavelength of light. Visible wavelengths are dependant on species receptors. Shortest wavelengths humans can perceive is 400nm (violet), longest is 700nm (red)
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Hue
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color that is perceived, corresponds to the dominant electromagnetic wavelength (frequency)
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Brightness
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(intensity) corresponds to height of EM wavelength or intensity of EM radiation
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Saturation (purity, richness, or paleness)
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corresponds to mixture of visble light, a pure color represents 1 wavelength & is said to be saturated.
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White light
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mixture of all wavelengths; called ADDITIVE color mixing; as more wavelengths are combined the perceived color becomes increasingly pale; however the color of an object we perceive is caused by SUBTRACTIVE color mixing
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pigments that lend color to objects absorb certain wavelengths, wavelengths NOT absorbed (subtracted) are what we perceive; combining more pigments causes less light to be reflected; combine many many pigments the object appears dark brown-black.
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2 major interpretations of color vision
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Trichromatic theory/Young Helmholtz theory
Oppenent-process theory |
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Trichromatic theory
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Color perception occurs thru the relative rates of response by 3 types of cones: Short, Medium & Long wavelength. Each cone is sensitive to a different set of wavelengths; Ratio fo activity across the 3 cone types determines the color; More intense light increases the brightness of color but doesn't change the ratio thus doesn't change the perception of the color itself.
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Color Vision deficiency (Color blindness)
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inipairment perceing color differences; often caused by either lack of a type of cone or cone abnormalities-most common form is distinguishing between red & green; Results from the long, medium wavelength cones having the same photopigment
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Opponent-process theory
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suggests we perceive color in terms of paired opposites:white-black, red-green, yellow-blue; possible mechanism for this theory is that bipolar cells are excited by one set of wavelengths and inhibited by another.
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Evidence for this theory includes:negative afterimages, prolonged stimulation of retinal color receptors after extended starting at one color iwll cuase the opposite color to be perceived when the stare is moved to a white background-staring at green causes red to be perceived.
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