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144 Cards in this Set
- Front
- Back
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Cornea
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The white part of the eye, refracts light and focuses it on retina
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Iris
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colored part of the eye, muscle that contracts to increase size of pupil or relaxes to decrease size of pupil
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Pupil
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opening in the middle of iris, can be controlled to let more or less light in, controlled by ANS
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Epithelial layer
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thick layer inside of the eye, totally black. absorbs light and keeps it from scattering into back of eye.
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Retina
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receptive organ of eye, thin sheet of neurons located at back of eye, where light is focused, image reflected on retina is upside down. “Backwards”, photoreceptors are at the back, then bipolar, then ganglion
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Fovea
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center of retina, densely packed with cones, no rods
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Optic disc/blind spot
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don’t have rods and cones on spot where optic nerve connects to retina. Not in the same place in both eyes, so don’t notice. Ganglion cells converge and exit retina
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Cells in the retina: Photoreceptors (function, type, structure)
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detect light, release transmitters onto bipolar cells, connect to ganglion cells.
Rods & cones Outer and inner segment, cell body, and synaptic terminal |
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Rods
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very sensitive, operate under low light, peripheral vision.
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Cones
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focal vision, acuity, color vision.
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Cells in the retina: Ganglion cells
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most important cells of retina, axons form optic nerve, take information to CNS
On & Off type |
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Cells in the retina: Amacrine cells
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run laterally, interneurons, influence connections between bipolar and ganglion cells
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Cells in the retina: horizontal cells
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run laterally, connect to photoreceptors and bipolar cells
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Lateral inhibition
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feedback, bipolar cells activated, other cells around it deactivated (inhibited), provides for sharp detection
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Differences and similarities between photoreceptors and neurons
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•Photoreceptors are graded (no all-or-none action potential)
•Outer segment works as a dendrite, receptive organ •Both have ion channels and transporters (Na and K) |
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Phototransduction
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in darkness, glutamate is released; when there is light, photoreceptor hyperpolarizes, less glutamate released
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Receptive fields
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region of the retina that must be illuminated to obtain a response in any given fiber. Center and surround.
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Center (receptive field)
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•Center is either on or off: either detects light or not light
On-center: cells fire in response to light Off-center: cells fire when light is off |
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Surround (receptive field)
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can be either on or off, allows us to detect edges, opposite response of center (on center = off surround)
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Low level visual processing
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Contrast, orientation, color, movement. Ganglion cells.
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Intermediate level visual processing
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Detect parts of objects, parsing image into visual surface and contours, distinguish foreground from background
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High level visual processing
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Object recognition, object representation, signals from other sensory modalities, emotional valence
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Primary visual pathway: optic nerve
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Optic nerve carries information from each visual hemifield to optic chiasm. Here, fibers from the temporal hemiretina (outer half of each eye) stay on the same side, joining the fibers from the nasal hemiretina (inner half of each eye) of the contralateral eye to form the optic tract.
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Primary visual pathway: optic tract
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Optic tract carries information from the opposite visual hemifield originating in both eyes (i.e. temporal hemiretina of left eye and nasal hemiretina of right eye) and projects into the lateral geniculate nucleus and pulvinar of the thalamus. Part of optic tract also goes to brainstem (superior colliculus, important in eye movement and prtectum, involved in pupillary reflex)
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Primary visual pathway: optic radiation
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Cells in the LG nucleus send axons along the optic radiation to the primary visual cortex, two pathways.
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Two pathways to the visual cortex: Upper tract
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through the parietal cortex, ends in upper bank of calcarine fissure, receives information from lower visual field.
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Two pathways to the visual cortex: lower tract
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down through temporal lobe, ends in the lower bank of the calcarine fissure, receives information from upper visual field.
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Two pathways from the visual cortex: ventral stream
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What pathway
Goes to temporal lobe (inferior temporal cortex) form recognition, object representation |
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Two pathways from the visual cortex: dorsal stream
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Where pathway
Goes to parietal lobe (posterior parietal area) Object locations, guides movement |
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Perceptual constancy
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See objects as invariant across transformations of an object such as size, position, and rotation
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Damage to the optic nerve
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lose vision in one eye
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damage to the right retina
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blind in right eye
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damage to the optic chiasm
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Lose of vision in temporal half of each visual field
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damage to optic tract
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Lose vision in opposite half of visual field
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Lesion of primary visual cortex on right
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lose left visual field
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Stroke in the parietal cortex on the left side
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Lose right lower visual field
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Stroke in the right temporal lobe
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Lose left upper visual field
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Lesion in the middle cerebral artery on the right
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Lose entire left side of visual field
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Lesion in Parietal cortex on left and infarct in lower bank of occipital cortex on the right
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Lose upper left, lower right
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Cochlea
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main auditory apparatus, encased in bone
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Auditory pathway
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Membrane vibrates as a result of sound, hair cells sense vibration, bending of hair cells transduced to electrical information. Bipolar cells carry to brain via auditory-vestibular nerve. Information goes into medulla, synapses at cochlea nuclei. Crisscrosses all over the place. Has one extra relay station (inferior colliculus). Synapses at medial geniculate in thalamus.
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Primary auditory cortex
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superior temporal gyrus
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What is special about the olfactory system?
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information doesn't go through the thalamus
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Olfactory cortex
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primitive, part of limbic system
medial aspect of temporal lobe |
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Gustatory system
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cranial nerves, fibers synapse close to medulla, go to medial posterior thalamus, then to primary gustatory cortex in front of the part of somatosensory area for tongue. Inferior frontal gyrus
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Muscle Fibers
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Two components that fit together to contract the muscle and move apart to relax muscle
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Contraction/relaxation of muscles
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Acetylcholine released onto muscle fibers, interacts with receptors, calcium comes in, some sodium, contract and relax; strength of contraction = how much NT released and on which muscles
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Alpha motor neurons
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Ventral gray matter of spinal cord, ventral roots, cholinergic.
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Primary motor cortex
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Precentral gyrus
Largest cells known to man |
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Pathway from cortex to spinal cord
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1. motor cortex
2. internal capsule 3. cerebral peduncle in midbrain 4. pons (some fibers synapse and go to cerebellum) 5. pyramidal tract: two white bundles travel down to medulla in pyramids, decussate, form corticospinal tract. 6. Corticospinal tract: spinal cord, lateral, next to gray matter 7. Ventral horn, synapse on alpha motor neurons 8. Send axons to muscles Information from cortex sent to spinal cord controls opposite side of the body. |
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Motor Association Areas: where are they and what do they do?
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Supplementary Motor Cortex
Premotor Area context rules of movement more about the idea of movement |
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Prefrontal Cortex & Movement
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rules, working memory, skill learning
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Multimodal association area (as it relates to movement)
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inferior parietal cortex.
sensory input necessary for motor function to be adequate, proprioceptive information (position of limbs, joints) Dorsal stream particularly important where object is, where hand is (peripersonal space, space right around us) |
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Kinesthetics
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form of movement
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Kinetics
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direct movement of muscles
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Extraocular muscles
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6 sets of muscles that move the eye in one direction or another
3 cranial nerves that control these muscles, motor nerves, unilateral (don’t cross), except one •Tremendous coordination (nuclei in midbrain, pons, make eye movement possible) |
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Motor Reflexes
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DRG one process goes to skin, other to spinal cord, sends axon collateral into ventral horn, synapses at alpha motor neuron, sends out reflex
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Stretch reflexes
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Nerve ending wrapped around organ in the middle of the muscle, senses how much stress there is (muscle spindle), depending on level of stress, tell muscle to contract or relax
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Two ways damage to motor system detected
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Muscle Tone
Reflexes |
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Damage to muscle itself or nerves, death of motor neurons in ventral horn spinal cord (Lou Gehrig’s/ALS)
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Flaccid Paralysis: muscles limp, cannot contract
Muscle atrophy (shrink) |
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Damage to muscle fiber
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Muscular dystrophy: muscles start to disintegrate, shape of muscle fiber changes
Muscles become bulkier, rubbery (replaced with fat) |
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Lower motor neuron disease
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Hyporeflexia, reflexes aren’t very brisk
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Upper motor neuron disease (i.e. internal capsule hemorrhage on one side)
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cerebral peduncle smaller on one side, medulla full of glial cells (sclerosis) decussate so opposite side of spinal cord affected, paralysis on opposite side (spastic paralysis, tone of muscles not decreased, resistance to forced movement of limbs). Hyperreflexia (reflexes enhanced) cortex is not controlling reflexes
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What happens if there is a cut and crush at cervical spinal cord on right side?
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Cutting: corticospinal tract fibers no longer going down (spastic paralysis, hyperreflexia)
Same side of body will be affected Crushing: flaccid paralysis on same side at cervical level (dead so don’t get communication from cortex) |
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Vestibular System
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Senses position of the head, each loop (semicircular canals) oriented in one direction
Located in inner ear |
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Vestibular pathway
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Hair cells detect motion
Signal goes to bipolar cells Send information to auditory-vestibular nerve Go to vestibular nuclei in medulla (synapse) Nearly all vestibular information goes to cerebellum Goes to thalamus |
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Vestibuo-ocular reflex
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move head, eye stays fixed (keep eye on focus of gaze). Move head too far, eye makes fast movement toward side of motion, focus of gaze changes
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Nystagmus
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pulsing of eyes towards the direction of movement, trying to focus eye on object when moving very fast
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Vestibulo-cerebellar system
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Cerebellum exerts control over vestibular system
Cerebellum inhibits vestibuo-ocular reflex (if you want to volitionally gaze on something else during head rotation) Input from vestibular nuclei, regulates balance, eye movement Adaptive learning (reflex changes when we wear glasses) |
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Vestibulo-cortical system
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Vestibular system sends axons from inner ear to vestibular nuclei, synapse in thalamus, axons from thalamus go to cortex
Not just one primary area |
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Unilateral problems
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dizziness, vertigo (one side active, one side not), abnormal nystagmus
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Bilateral problems
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problems fixating eyes (reflex paralyzed)
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Vestibulo-ocular system
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coordinates movement, reflexes that control gaze
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Vestibulo-spinal tract
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maintains balance, postural reflexes
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Spinal cerebellum
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Midline/vermis
Two tracts: anterior and posterior (spino-cerebellar tracts), carry information to cerebellum from spinal cord. One carries proprioceptive information, the other carries information about what the motor neurons are doing Controls limb movement, gait, body movements |
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Cerebral cerebellum
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Cerebellar hemispheres
Sends information up to cortex (especially motor cortex) Receives input from pons (information from internal capsule, synapse on pontine nuclei decussate, go to opposite cerebellum) Planning and executing movements Eye blink reflex, hand-eye coordination Cognitive functions: sense of time, word associations, coordination of complex tasks, language, learning |
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Output of cerebellum
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Four sets of nuclei, axons synapse and exit and go to other places, with exception of vestibular system, feedback to vestibular system goes directly to vestibular nuclei
Purkinje cell: output cell of cerebellum, go to cerebellar nuclei and then out (except vestibular) |
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Superior cerebellar peduncle
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output to cortex, fibers partly synapse and partly don’t, do this at level of midbrain
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Inferior cerebellar peduncle
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input from vestibular nuclei, spinal cord, proprioceptive information (go through medulla)
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Middle cerebellar peduncle
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connected to pons, input from contralateral cerebral cortex
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The cerebellum is a "double-crosser"
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Spinocerebellar tract: fibers cross in spinal cord and then again in cerebellum, damage to cerebellum effects same side of body.
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Pathway from cortex to cerebellum
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information travels down to pons on same side, synapses, secondary fibers cross, enter opposite cerebellar hemisphere
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Pathway from cerebellum to cortex
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information goes to pons, go to red nucleus, synapse, secondary fibers cross over at level of midbrain. Go to ventral lateral nucleus of thalamus
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Cerebellar damage
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Loss of balance, inability to stand or walk
Intention tremor (tremor at end of movement), deficit in planning to reach, system doesn’t know where to stop Reflex: doesn’t know when to stop, pendulum type movement Difficulty with repeated movement Lose automatic control of muscle movement Eye-blink response (puff of air makes eye blink, paired with sound), gone with cerebellar damage Eye-hand coordination |
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Striatum (input, output)
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Caudate nucleus & Putamen
Major input areas (cortical and dopaminergic, substantia nigra pars compacta) brings dopamine in, can be inhibitory or excitatory Send output to substantia nigra pars reticulata and to segments of globus pallidus (inhibitory) |
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Substantia Nigra
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pars compacta (dopaminergic): neurons project to striatum
pars reticulata |
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Globus Pallidus
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Internal segment
External segment: sends information to subthalamic nucleus |
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Subthalamic nucleus
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sends output to SN pars reticulata and GP internal segment (excitatory)
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Input to basal ganglia from cortex
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nearly all association areas, particularly from motor cortex to striatum
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output from basal ganglia
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Main output pathway of basal ganglia goes through two nuclei
•Internal segment of GP •Pars reticulata SN Output goes to nuclei in thalamus: ventral lateral and ventral anterior |
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Direct and Indirect pathways
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One pathway initiates movement, other inhibits movement (unwanted movement)
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Neurotransmitters in Basal ganglia
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Most parts use GABA (inhibitory), except subthalamic nucleus that uses glutamate
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Basal Ganglia: motor functions
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Scaling movement: how hard, fast should movement be? How much force should I use?
Decide sequence of movement Initiate movement Select action (learning and reinforcement play a role) |
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Basal Ganglia: emotion/motivation
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Emotions, motivation, learning
Dopamine: reward system (ventral part of striatum) |
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Basal ganglia: oculomotor movement
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Same functions as for motor system, but with eye movement
Input from premotor cortex (frontal eye fields) |
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Huntington's Disease
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Disorder of Basal Ganglia
Difficulty inhibiting movement (dancing/chorea) unwanted motor activity, particularly of upper limbs, cells in striatum die (less inhibition in GP, more inhibition of subthalamic nucleus) |
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Parkinson's Disease
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Disorder Basal Ganglia
Resting tremor, difficulty initiating action, not moving right or literally not moving (muscle rigidity). Lack of dopamine, death of dopaminergic neurons in SN pars compacta (Lewy bodies) |
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Lesion of subthalamic nucleus
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hemiballism, chorea on one side of body
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Autonomic Nervous System
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•Smooth muscles
•Cardiac muscles •Endocrine system |
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Preganglionic Neurons
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Central control of ANS
Cell bodies in brainstem and spinal cord Axons that go into autonomic ganglion cells are different for each division of ANS Preganglionic cells in both divisions use ACh, excite receptors on ganglionic neurons |
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Autonomic Ganglion Cells
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send axons to smooth or cardiac muscles
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Five criteria distinguish parasympathetic from sympathetic division
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•Segmental organization of preganglionic neurons in spinal cord and brain stem
•Peripheral locations of ganglia •Types and locations of end-organs they innervate •The effects they produce on end-organs •Neurotransmitters employed by postganglionic neurons |
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Sympathetic Division
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Controlled by cells inside gray matter of spinal cord in thoracic and lumbar regions, send axons into spinal chain ganglia, one on each side of spinal cord.
Secondary fibers from ganglionic cells go out to organs where they innervate NT for postganglionic cells is norepinephrine Function: prepares organism to respond. Fight or flight. Diffused, prolonged (can innervate many different organs and effect lasts awhile) |
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Parasympathetic Division
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Control from CNS comes from cranial nerve and sacral spinal cord
Cell bodies inside gray matter, axons project to peripheral nerves through ventral roots Parasympathetic ganglia lie close to site of innervation For postganglionic cells NT is ACh (released onto organ they are innervating) Function: eating, procreation, calms and stabilizes system |
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Autonomic reflexes: Peristalsis
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Contraction of gut, esophagus. Propels contents of GI tract in oral-anal direction.
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Autonomic reflexes: baroreceptor reflex
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contraction and relaxation of blood vessels, stand up and blood doesn’t drain out of head. Regulating blood pressure when person goes from sitting to standing. Decrease in blood pressure when person stands up triggers medulla to produce reflexive suppression of parasympathetic activity and stimulation of sympathetic activity.
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Autonomic reflexes: micturition
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bladder emptied by parasympathetic pathway, contracts bladder and relaxes urethra. Sympathetic system allows bladder to fill by stimulating urethra and inhibiting parasympathetic pathway.
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Hypothalamus (three functions)
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•Controls ANS, controls pituitary gland directly and indirectly through hormone-releasing neurons
•Connection with many drives and behaviors •Master gland of body, in charge of hormonal system, done through pituitary gland |
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Nucleus of solitary tract
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major way station for sensory info coming in and motor info going out
Projects to brain stem and spinal cord networks that control and coordinate autonomic reflexes Projections that integrate autonomic with neuroendocrine and behavioral responses |
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Two areas of cerebral cortex involved in autonomic system
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•Anterior cingulate cortex
•Insula Control hypothalamus |
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Homeostasis: 3 crucial principles
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1. Set point: target for regulation, like a thermostat (body temperature, water level, energy), hypothalamic system adjusts based on set point
2. Gain: accuracy of adjustment, how much variation should there be 3. For system to know what to do, needs feedback |
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Pituitary gland (divisions)
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•Posterior division (neurohypophysis)
•Anterior pituitary division (adenohypophysis) •Through these two mechanisms, hypothalamus controls entire endocrine system |
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Neurohypophysis
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receives axons from hypothalamus that directly release hormones into circulation (oxytocin, vasopressin)
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Adenohypophysis
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neurons from hypothalamus that innervate and release hormones (stimulating and inhibitory), some go into bloodstream, some stay in adenohypophysis, and influence cells that make other hormones
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Anticipatory control
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•Feedback system
•Don't eat or drink ourselves to death |
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Motivational behavior
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Makes organism act on what internal needs are
Provided by external and internal stimuli •Internal stimuli: set point errors, circadian rhythm •External: incentive stimulus, what is outside of us that can satisfy need, bring balance Positive feedback between response of organism and stimulus, the more organism interacts with external stimulus, stronger drive to get to it (acting on external stimulus is reinforcing itself, i.e. drug abuse) |
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Reward system in brain
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electrode stimulation will always cause behavior to get more stimulation, extremely rewarding
Pathway: stimulation of medial forebrain bundle, involves basal ganglia motivation system, nucleus accumbens, ventral tegmental area when stimulated release dopamine into nucleus accumbens (ventral part of caudate) and nucleus accumbens connects to globus pallidus, output to medial prefrontal cortex. Rewarding brain system increases output in this system, levels of dopamine increased. |
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Drug addiction
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•Inhibit dopamine uptake
•Stimulate release of dopamine (amphetamines) •Drugs are like reward stimulation |
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Drug tolerance
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Need more to get same effect. System adjusts so you don’t respond as much as you used to
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Drug Dependence
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Addictive behavior changes the neurophysiology of the system. Cessation of drug use unmasks the abnormal physiological state, resulting in withdrawal.
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Associative learning
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part of drug dependence, person can be drug free and as soon as they are in the presence of cues associated with drug, craving returns. Learned process, synaptic changes
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Dopamine and expectancy
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Dopamine activation tells brain “what I am getting is better than what I expected”. Drugs are addictive because brain says this is much better than what I expected.
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Frontal eye fields
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part of premotor cortex that coordinates muscles in eyes and moving well in connection with the rest of the body
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Emotions work through three systems in the body
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•Endocrine system
•Autonomic system •musculoskeletal system: facial expressions |
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Core Limbic Areas
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•hippocampus
•amygdala (not really a cortex) •primary olfactory cortex Connected to hypothalamus |
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Paralimbic areas
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Connects core limbic areas to neocortex
•parahippocampal gyrus, cingulate: area that connects hippocampus to neocortex •insula, temporal, orbitofrontal: connect olfactory cortex to neocortex |
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Limbic striatum
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Ventral striatum/nucleus accumbens
Hedonic component/pleasure aspect of feeling states Involved in affective disorders |
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Brainstem and emotional control
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Central gray/periaqueductal gray in midbrain: where the hypothalamus projects to, important for emotional expression. Controls freezing behavior.
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Hypothalamus & emotion control
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head of internal state, has no way of interacting with outside world directly. relies on motor cortex to act on outside world and somatosensory cortex to know what's happening in the outside world.
talks to core limbic areas, core limbic areas want to tell rest of cortex about it, go through paralimbic areas. But hypothalamus cannot talk to paralimbic directly, goes through core limbic areas. |
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Multimodal association areas and emotional control
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at the center of everything. tell motor system what to do based on what somatosensory information brought in, but also know about internal state.
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Amygdala
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•necessary for fear/aversive conditioning
•important for the pairing of conditional and unconditional stimulus in terms of emotional reaction •Involved in detecting emotional responses in others as well as expression of emotion •association of neutral stimuli of rewards |
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Lateral nuclei of amygdala
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receptive part of amygdala, information from cortex, pairing,
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Central nuclei of amygdala
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output, fear response itself, goes to hypothalamus and periaqueductal gray in brain stem
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Damage to amygdala
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•aversive learning gone
•difficulty recognizing emotion in other people •no autonomic response to fear •fear, anxiety •processing cues in addictive behavior, no negative processing |
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Hippocampus
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memory aspects of emotion, conscious memory (i.e. person told shock is coming)
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Social emotions
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•Empathy
•Embarrassment •Guilt •Pride |
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Orbitofrontal cortex
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Important in social emotions, moral decisions (active preceding the decisions how we are going to act in relation to other people)
Damage: •personality problems •antisocial behaviors/sociopathic (acquired sociopathy) |
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Cingulate cortex
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Different parts of cingulate light up for different emotions; imagining emotions
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Insula (function and damage)
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Emotional reaction to pain
•Damage to right insula: impairs social feelings, fail to guess emotions in other people •Damage to the left insula: shown to lead to suspension of addictive behavior (i.e. nicotine), insula seems to be associating external stimuli with pleasure |
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Hemispheric Dominance
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Right side dominant for processing emotions
•Damage to left hemisphere results in catastrophic depression, see things negatively •Right hemisphere damage: inability to detect emotions in others •Control of muscles: emotional facial expression in humans is predominantly a left sided phenomenon |
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Multimodal association areas in visual system
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What pathway: fusiform cortex, facial recognition. prefrontal cortex. inferior temporal lobe
Where pathway: posterior parietal cortex (paying attention to space), sensory information feeding into motor cortex. |
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Cortical control of reflexes
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regulate the strength of reflexes
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Four basal ganglia pathways
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1. Motor circuit: connections to motor cortices
2. Limbic: emotion/motivation, connected to anterior cingulate area, orbitofrontal cortex 3. Prefrontal (associative): executive function 4. Oculomotor circuit: eye movement, connected to supplementary eye field, frontal eye field |
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Kluver-Bucy Syndrome in monkeys
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results from bilateral lesions of amygdala
Symptoms: 1. docility 2. dietary changes 3. Hyperorality (explore objects orally) 4. Hypersexuality 5. Visual agnosia (cannot recognize familiar objects/people) |
