Term
|
Definition
| pyramidal decussation - motor |
|
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Term
|
Definition
| • Transverse fibers of the pons cover the ventral surface |
|
|
Term
| Gray matter of the spinal cord |
|
Definition
Doral - sensory
Ventral - Motor |
|
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Term
| Gray matter of the brainstem |
|
Definition
The pontine flexure and the fourth ventricle influence the way the alar and basal plates are laid out in the brainstem compared to the spinal cord.
Sensory moves laterally
Motor moves medially |
|
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Term
| Organization of brainstem nuclei |
|
Definition
the gray matter lies close to the central canal/ventricle with the white matter further away
• Sensory nuclei are lateral, motor nuclei are medial, visceral nuclei are in between |
|
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Term
|
Definition
(Most CN part of the PNS)
(Ipsilateral)
Cranial nerves with nuclei in the brainstem exit on the anterior/ventral
surface of the brainstem (except for CN IV)
• 3 sensory nerves
• 5 motor nerves (one has a visceral component as well as a somatic component)
• 4 mixed nerves (sensory plus motor) |
|
|
Term
| Part of the PNS (except CN I and CN II) |
|
Definition
which aren’t found in the brainstem
Oligodendrocytes (MS vision deficits) |
|
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Term
|
Definition
Contralateral
• CN IV – Trochlear – Moves eyes (MOTOR – SOMATIC) |
|
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Term
| Cranial Nerves: Names and functions |
|
Definition
• CN I – Olfactory – Smells (SENSORY - SOMATIC)
• CN II – Optic – Sees (SENSORY - SOMATIC)
• CN III - Oculomotor – Moves eyes, constricts pupil, accommodation (MOTOR – SOMATIC AND VISCERAL)
• CN IV – Trochlear – Moves eyes (MOTOR – SOMATIC)
• CN V – Trigeminal – Chews and feels front of head (MIXED – SENSORY AND MOTOR - SOMATIC)
• CN VI – Abducens – Moves eyes (MOTOR – SOMATIC)
• CN VII – Facial – Moves the face, tastes, salivates, cries (MIXED – SENSORY AND MOTOR – SOMATIC AND VISCERAL)
• CN VIII - Vestibulocochlear – Hears, regulates balance (SENSORY – SOMATIC)
• CN IX – Glossopharyngeal – Tastes, salivates, swallows, monitors carotid body and sinus (MIXED – SENSORY AND MOTOR – SOMATIC AND VISCERAL)
• CN X – Vagus – Tastes, swallows, lifts palate, talks, communication to and from thoraco-abdominal viscera (MIXED – SENSORY AND MOTOR – SOMATIC AND VISCERAL)
• CN XI – Accessory – Turns head, lifts shoulders (MOTOR – SOMATIC)
• CN XII – Hypoglossal – Moves tongue (MOTOR – SOMATIC) |
|
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Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| CN V VI VII VIII (Location) |
|
Definition
|
|
Term
| CN IX X XI XII (Location) |
|
Definition
|
|
Term
|
Definition
• Cranial nerve nuclei aren’t necessarily isolated to the portions of the brainstem with which they are associated (CN V, VII, VIII bridge at least 2 divisions)
• The levels are where the cranial nerves themselves enter/leave (there is one exception – CN VII has entry points in both pons and medulla)
• MOST cranial nerves don’t cross. Except IV |
|
|
Term
|
Definition
(Memory - hippocampus)
hippocampus - hypothalamus - thalamus - orbitofrontal cortex combined with gustatory input
(Damage to unilateral is no deficit, damage to bilateral is anosmia)
important with food flavor
• Sensory only – transmits information about smell
• Chemoreceptors in the nose send messages to the inferior frontal
lobes where the olfactory bulb is housed
• From there, travel along olfactory cranial nerve to the hippocampus in the temporal lobe. |
|
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Term
|
Definition
• Sensory only – carries information from the photoreceptors in the retina to the optic chiasm (where some information crosses), to the thalamus, then to the occipital lobe (some information goes to the superior colliculi, most to occipital lobe).
• Damage to the optic nerve itself will lead to blindness in the affected eye
(Cut optic nerve retina, will be blind in the affected eye) |
|
|
Term
|
Definition
• Motor only – mostly somatic, but some visceral too
• Somatic: Controls most extraocular eye muscles (all but lateral rectus [CN VI] and superior oblique [CN IV])
(CN III opens eye, CN VII closes eye)
– moves eye up, down, medially, laterally, downward medial deviation). Also opens eyelid
• Visceral: Controls pupillary constriction when light is shined on the eye. Also contributes to accommodation (lens changing shape when change focal distance)
- Ability to accommodate for near and far |
|
|
Term
| CN III - Oculomotor (Two Nuclei) |
|
Definition
• Somatic: Oculomotor nucleus in the midbrain at the level of the superior
colliculus (Given that it’s motor, WHERE would you expect the nucleus?)
• Visceral: Edinger-Westphal nucleus – just adjacent to the oculomotor nucleus
• (Unfortunately, it violates our wonderful organization of the brainstem; it is MEDIAL of the oculomotor nucleus.) |
|
|
Term
|
Definition
• Motor only – somatic.
• Controls the superior oblique extraocular eye muscle CONTRALERALLY (only CN to cross). Pulls the eye down and laterally
• Also exits on dorsal surface of brainstem and then wraps around (only CN to do that too).
• Trochlear nucleus is in the midbrain at the level of the inferior colliculi |
|
|
Term
|
Definition
(ophthalmic, maxillary, mandibular)
• Sensory portion – carries sensation from the face, head, cornea, inside of the mouth.
• Sensory nucleus is the largest of the CN nuclei – extends from midbrain into the spinal cord
• Subdivided into three subnuclei: mesencephalic nucleus, main sensory nucleus, spinal trigeminal nucleus
• Motor portion – innervates the jaw muscles that control chewing
• Nucleus for this portion is the motor nucleus of the trigeminal – in the middle-pons. |
|
|
Term
|
Definition
• Most frequent disorder of CN V.
• No sensory or motor deficits present. Person experiences severe pain, usually lasting seconds. The pain appears in one of the three nerve distributions
• Often spontaneous occurrence of pain, though can be triggered by things like a breeze on the face, chewing, yawning, brushing teeth, etc.
• Can be caused by herpes zoster ophthalmicus (shingles virus affecting the ophthalmic nerve), or things like nerve compression
• Treatments can include medications and surgery, but those are not always successful |
|
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Term
|
Definition
• Motor only – somatic.
• Controls the lateral rectus, which moves the eye laterally
• Abducens nucleus is in the caudal portion of the pons |
|
|
Term
|
Definition
• Muscles for facial expression
• Eyelid closing
• Stapedius muscle (stapes of the middle ear) – helps to regulate volume
• Motor nuclei are in the pons (sensory are in the medulla).
Somatic motor portion of the facial nerve originates from the facial nucleus and takes a circuitous route through the pons before it leaves.
• Visceral motor portion
• Contributes to crying and salivation
• Visceral sensory portion
• Innervates the taste receptors
• Somatic sensory portion - potion of the ear |
|
|
Term
|
Definition
CN VII
• Occurs when facial nerve swells and becomes compressed
• Herpes simplex 1 virus is the cause over half the time though can also result from trauma
- dropping ipsilateral
- hypersensitive to noise |
|
|
Term
| CN VIII - Vestibulocochlear |
|
Definition
• Sensory – contains two branches.
• Auditory branch. Comes from hair cells in the inner ear and travel to the vestibular nucleus in the brainstem. Sensory impulses are sent when vibrations of the fluid in the cochlea cause action potentials
• Vestibular branch - movement and positioning of the head, balance, and equilibrium |
|
|
Term
|
Definition
Sensory and Motor
• Sensory – transmits information on taste AND general sensation on the posterior third of the tongue.
Synapses on the rostral part of the nucleus solitarius (gustatory nucleus) in the medulla.
• Visceral sensory – (Blood Pressure) sends information from carotid body and sinus about blood pressure. Synapses on the caudal part of the nucleus solitarius. |
|
|
Term
|
Definition
Motor and Sensory
• Somatic sensory – innervates cutaneous areas in the back of the ear.
• Special sensory – innervate taste buds of the epiglottis.
• Visceral sensory – from the pharynx, larynx, trachea, esophagus, thoracic and abdominal viscera. (Info from gut)
• Somatic motor – important for swallowing and speech. Originates in the nucleus ambiguus in the medulla
• Visceral motor – carries parasympathetic information influencing gut motility, heart and respiratory rate. (Food digestion) |
|
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Term
|
Definition
- Motor
• Has both cranial AND SPINAL portions
- (Head turn and shoulder shrug)
- Sternoclavidomastoid and upper trap |
|
|
Term
|
Definition
- Somatic Motor
• Innervates the majority of the tongue which is important for speech
• Axons arise from the hypoglossal nuclei in the medulla |
|
|
Term
|
Definition
| Full comprehension and cognition of speech, but tongue speech impairment |
|
|
Term
| Overview of the reticular formation |
|
Definition
• The core of the brainstem
• Poorly localized
• Nuclei come in a wide variety of sizes.
• Highly connected to other parts of the nervous system
• Has several major functions:
• Regulation of consciousness
• Control of muscle tone (Pain)
• Control of pain |
|
|
Term
| Structural features of the reticular formation |
|
Definition
• Dendritic trees have a lot of overlap with each other
• Axons of ascending and descending tracts give off a lot of collateral branches
• Cells of reticular formation receive information from numerous sources, with sensory, motor, somatic, and visceral information (though one category of information will dominate in different areas)
• Cells from the reticular formation have widespread output to other cells |
|
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Term
| Nuclei/columns of the reticular formatio |
|
Definition
• Raphe nuclei
• Gigantocellular reticular nuclei AKA Central cells
• Parvocellular reticular nucleus AKA Lateral reticular nucleus |
|
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Term
|
Definition
(Serotonin synthesis - mood)
7 different nuclei (Don't need to know names)
• Important for serotonin synthesis, mood regulation, consciousness, pain modulation.
• Located along the midline
• Synapse with several pathways, including the medial longitudinal fasciculus |
|
|
Term
Gigantocellular reticular nuclei AKA central
cells |
|
Definition
• Centrally located (largest)
• Highly connected to multiple pathways and other nuclei (including the vestibular nuclei, pyramidal tract - motor info down, spinothalamic tract - pain, medial longitudinal fasciculus - eyes moving together)
- Movement!
(know category and what they do, no names) |
|
|
Term
| Parvocellular reticular nucleus AKA lateral reticular nucleus |
|
Definition
• Located laterally in the more caudal part of the reticular formation.
• Contributes to autonomic nervous system |
|
|
Term
| Pathways and the reticular formation |
|
Definition
Eyes are "Yoked" - meaning similar aptitude an usually same direction because of the medial longitudinal fasciculus.
• Medial longitudinal fasciculus – helps to coordinate eye movements (so that the eyes are “yoked”). Also important for vestibular system, including linking it to the visual system
• Reticulospinal pathways – help to regulate motor activity, including muscle tone through influencing the activity of both alpha and gamma motor neurons (what is the difference between these?) Also important for reflexes and for modulation of pain |
|
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Term
| Reticular formation and integration |
|
Definition
(Screening, as the gate keeper - how much info to be sending)
• Part of the role of the reticular formation is to integrate information from numerous places
• It also plays a large role in screening information prior to sending it to the cortex.
• It amplifies information critical to survival and habituates the system to information that is not as important
• This interconnection with other systems is so great that we will revisit the reticular formation when we cover future topics, including the autonomic nervous and vestibular systems |
|
|
Term
| Examples of Reticular integration |
|
Definition
| Bouncing, jumping, fast movement |
|
|
Term
| Reticular activating system |
|
Definition
• The RAS is responsible for alertness and wakefulness
• Part of its job is to get the cortex to pay attention to important input
• Primarily located in the rostral midbrain. Connections to the thalamus and hypothalamus. This is made up of several circuits |
|
|
Term
| Reticular inhibiting system |
|
Definition
(Not paying attention to everything, but attention to important things)
• The RIS is important for calming and sleep
• Also helps with things like habituation (very important)
• Extends from caudal midbrain to the caudal medulla. Connections to the thalamus and hypothalamus |
|
|
Term
| Clinical relevance of the reticular formation |
|
Definition
• Sensory avoiders may have overactive reticular activating system or underactive reticular inhibiting system – can’t screen out irrelevant input
• Sensory seekers may have an overactive reticular inhibiting system or underactive reticular activating system – leads to difficulty registering sensory information. |
|
|
Term
| Components of the diencephalon |
|
Definition
• Epithalamus - pineal gland (Rostral)
• Subthalamus - basal ganglia circuit (movement)
• Hypothalamus - ANS hormone regulation (Hemostasis/Limbic System)
• Thalamus |
|
|
Term
|
Definition
• Made up of several structures, most important of which is the pineal gland, an unpaired structure rostral to and in between the superior colliculi.
• Appears to have a role in circadian rhythm and cognitive/emotional behaviors. Also influences hormonal secretion from glands including pituitary. |
|
|
Term
|
Definition
• Wedge-shaped
• Marks the transition between the thalamus and the midbrain of the brainstem
• Functionally, part of basal ganglia circuit with an important role in movement. |
|
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Term
|
Definition
(Homeostasis)
• Small in size, but has some very important contributions:
• Regulates the autonomic nervous system
• Releases hormones from the pituitary gland, adrenal glands, and the pineal
gland
• Regulates temperature
• Regulates hunger and thirst
• Regulates reproductive behaviors
• Regulates circadian rhythms and fatigue
• Contributes to emotional regulation
• Primarily from the limbic system
• Emotions, learning, memory
• Also gets information from the vascular system
• This allows monitoring of chemical changes in cerebrospinal fluid and bloodstream |
|
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Term
| Output from the hypothalamus |
|
Definition
| Reciprocal for limbic system, pituitary, etc. |
|
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Term
| Lesions to the hypothalamus |
|
Definition
Damage requires bilateral
• Many pathological conditions, especially different types of tumors, can damage the hypothalamus.
• Tumors can involve structures near the hypothalamus, such as the pituitary gland
Ex:
diabetes insipitus, deficits in endocrine function, disruption in body temperature regulation, interruption of circadian rhythms, and emotional/behavioral changes
- Prader-Willi syndrome |
|
|
Term
|
Definition
• The two thalami are connected, but not axonally. Structure that connects them is called the (massa intermedia)
• Bilateral. Found between the posterior limb of the internal capsule (laterally) and the third ventricle (medially)
• All sensory systems (Gateway to Cortex) Exception CN I
• Information from the cerebellum and the basal ganglia goes through the thalamus on its way to the cortex (Movement) |
|
|
Term
| internal medullary lamina |
|
Definition
| Divides the thalamus into sections |
|
|
Term
| Functions of the thalamus |
|
Definition
• Sensory integration
• Receives, starts processing, and forwards sensory information to the cortex (except olfaction)
- Primary and association
- Link to Sensation --> pleasure vs unpleasure
• Motor integration
• Receives and sends projections from/to basal ganglia and cerebellum
• Consciousness - alertness |
|
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Term
| Categories of nuclei in the thalamus |
|
Definition
(Sending an deceiving communication)
• Specific relay nuclei - unimodal, no integration
• Association nuclei -
• Intralaminar (AKA nonspecific) nuclei - |
|
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Term
|
Definition
(Contralateral)
This occurs after an infarct involving the thalamogeniculate branches of the posterior cerebral artery. |
|
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Term
| Specific SENSORY relay nuclei |
|
Definition
• Ventral posterolateral
• Gets input from the medial lemniscus (dorsal columns) and spinothalamic tracts
• Cortical output to the somatosensory cortex
• Carries sensory information from the body
• Ventral posteromedial
• Gets input from the trigeminothalamic tract |
|
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Term
|
Definition
| • Gets auditory input via the inferior colliculus |
|
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Term
|
Definition
(Occipital Lobe)
• Gets visual input via the optic tract |
|
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Term
|
Definition
(Motor Relay Nuclei)
• Ventral anterior
• Gets information from the basal ganglia |
|
|
Term
|
Definition
(Motor Relay Nuclei)
• Gets information from the cerebellum and basal ganglia |
|
|
Term
| Specific LIMBIC relay nuclei (One Input) |
|
Definition
• Anterior
• Gets information from the mammillothalamic tract and the hippocampus
• Projects to the cingulate gyrus
• Lateral dorsal
• Gets information from the hippocampus • Projects to the cingulate gyrus |
|
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Term
| Association nuclei (MultiModal/Blending) |
|
Definition
• Do not receive input from a single source
• Instead, receive multimodal inputs |
|
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Term
|
Definition
(Association Nuclei)
• Gets information from the prefrontal cortex, olfactory (cortical), and limbic system structures (e.g. amygdala)
• Projects to the prefrontal cortex
• Important for emotions and memory |
|
|
Term
|
Definition
(Association Nuclei)
• Gets information from the parietal, temporal, and occipital lobes, in addition to the visual system |
|
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Term
|
Definition
• Gets input from and projects to the parietal, occipital, and temporal lobes
(Association Nuclei) |
|
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Term
|
Definition
• Project to widespread areas of the cerebral cortex
• Also have reciprocal relationships with subcortical structures/systems
including the basal ganglia and limbic system
• Extensively interconnected
• Considered rostral extensions of the reticular formation
• Centromedian is the largest of these nuclei |
|
|
Term
|
Definition
• Doesn’t fall into the categories of thalamic nuclei as previously described
• Not associated with the reticular formation
• Forms a shell around the thalamus (No projection) |
|
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Term
|
Definition
| Neocortex (Cortex EF), paleocortex (Medulla - emotion), and Archicortex (Brainstem and deep structures) |
|
|
Term
|
Definition
• Made up of the hippocampus
• Deep in the temporal lobe
• Most primitive of the regions
• On a cellular level, has three layers
• Important for learning and memory |
|
|
Term
| Mesocortex(AKApaleocortex) |
|
Definition
• Made up of the piriform cortex (AKA perirhinal cortex; important for olfaction) and the
parahippocampal gyrus (part of the limbic system)
• Transitional between the hippocampus and the outermost region – acts as relay
• On a cellular level, has three to five layers (varies throughout the structure) |
|
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Term
|
Definition
• Outermost region
• Made up of the primary motor cortex, primary sensory cortices, association cortex – about
90% of the cerebral cortex volume in humans (about 50-80% of the brain as a whole) • On a cellular level, contains six layers (for the most part) |
|
|
Term
|
Definition
Cortex Cell
• Conical shape of cell bodies.
• Long axons
• Leave the cerebral cortex to go to other cortical areas (ipsilaterally or contralaterally). Can also terminate in subcortical structures
• Main output neuron of the neocortex |
|
|
Term
|
Definition
Cortex Cells
• Most common are stellate, or granule, neurons
• Varied in shape
• Have numerous short dendrites that extend in all directions and a short axon that connects with nearby neurons
• The main interneurons of the neocortex |
|
|
Term
|
Definition
| Multipolar, small, and wide assortment of shapes |
|
|
Term
|
Definition
Six layers in most places
• Most superficial (layer I) is fiber-rich and cell poor (mostly made up of axons)(Interneuron)
• Layer II is the external granular layer (one of two layers to contain granular cells) (input)
• Layer III is the external pyramidal layer (one of two layers to contain pyramidal cells)
• Layer IV is the internal granular layer (the other layer to contain granular cells)
• Layer V is the internal pyramidal layer (the other layer to contain pyramidal cells)
• Layer VI (the deepest) is the multiform layer – important for connecting cortex and thalamus |
|
|
Term
|
Definition
Layers II & V robust
Pyramidal cells - output and motor cortex |
|
|
Term
|
Definition
Granular cells - Layer II & IV
These don’t tend to project to areas outside the cortex. Instead, they communicate with other cortical areas. |
|
|
Term
|
Definition
| • Areas 1,2,3 are the primary somatosensory cortex |
|
|
Term
|
Definition
• Area 5 (posterior to primary somatosensory cortex in the parietal cortex)
• Gets input from vestibular and motor areas as well as somatosensory cortex. Believed to
contribute to sense of personal and extrapersonal space, along with memories of environment and movement |
|
|
Term
|
Definition
• Area 7 (posterior to primary somatosensory cortex and area 5 in the parietal cortex)
• Important for synthesizing information from somatosensory (esp proprioception) and vision for spatial perception |
|
|
Term
|
Definition
• 3 is on the edge of the primary motor area in the parietal cortex. Believed to be important for
perception of proprioception. Probably gets input from vestibular system as well. Appears to be partly responsible for creation of the body map |
|
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Term
|
Definition
• Area 4 is the primary motor cortex
• Located in the frontal lobe. Consists of the precentral gyrus on the lateral surface and the
anterior portion of the paracentral lobule on the medial surface. Remember that this area is where the motor homunculus is housed. Essential for voluntary movement |
|
|
Term
|
Definition
• Contains the premotor cortex, the supplementary motor area, and part of the frontal eye field
• Located in the frontal lobe. Made up of part of the precentral gyrus, along with the middle and superior frontal gyri. Important for motor planning, posture, and helping to control voluntary eye movement |
|
|
Term
|
Definition
Rest of the frontal eye field
• Located in the frontal lobe. Shares the middle and superior frontal gyri with area 6. Important
for helping to control voluntary eye movement. |
|
|
Term
|
Definition
|
|
Term
| Brodmann’s area (18 & 19) |
|
Definition
• These areas surround area 17
• They are responsible for starting to interpret and recognize visual information |
|
|
Term
|
Definition
primary auditory cortex
• Located in the temporal lobe at the transverse temporal gyri |
|
|
Term
| Brodmann’s area (42 & 22) |
|
Definition
Interpret information
• Area 42 is in the temporal lobe and shares the transverse temporal gyri with area 41
• Area 22 is in the temporal lobe at the superior temporal gyrus (the posterior portion of this
area in the dominant hemisphere is also home to Wernicke’s area) |
|
|
Term
|
Definition
Wernicke’s area
language comprehension - understanding written and spoken language |
|
|
Term
| Brodmann’s area (44 & 45) |
|
Definition
Broca's area
• Located in the frontal lobe in the dominant area at the opercular and triangular parts of the inferior frontal gyrus
• Important for language production |
|
|
Term
|
Definition
prefrontal cortex, dorsolateral prefrontal cortex
• In the frontal lobe
• Encompasses superior, middle, and inferior frontal gyri rostral to area 6
• Important for many aspects of cognition, including cognitive planning of movement, personality, etc. |
|
|
Term
| Brodmann’s area (23 & 24) |
|
Definition
part of the limbic association cortex
• Make up the cingulate gyrus |
|
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Term
|
Definition
| part of the limbic association cortex • Makes up the parahippocampal gyrus |
|
|
Term
|
Definition
Big Picture, not logical, emotional language
• Controls motor and sensory functioning of the left side of the body
• Involved in interpretation of abstract/creative information, for things like understanding jokes and gaining meaning from stories, interpretation of body language and verbal tone, perception |
|
|
Term
|
Definition
Logical, producing and comprehension of language
• Controls motor and sensory functioning on the right side of the body
• Very important for language. Broca’s and Wernicke’s areas are usually housed on this side of the brain (note that there are some aspects, the “emotional” aspects, of language that are typically housed on the right)
• More analytic; responsible for interpretation of the concrete meanings of words, math, categorization of shapes.
• Can think of this side of the brain as the “detail oriented” side |
|
|
Term
| Deficits after right side brain damage |
|
Definition
• Sensory and motor loss on the left side of the body
• Visual-spatial disorders
• Body scheme perception disorders
• Perceptual disorders (including a condition called “hemi-inattention” AKA “unilateral spatial neglect”)
• Can see motor planning issues, on the left side of the body |
|
|
Term
| Deficits after left side brain damage |
|
Definition
• Sensory and motor loss on the right side of the body • Aphasia (receptive and/or expressive)
• Acalculia
• Agraphia
• Alexia
• Apraxia (motor planning and/or object use) |
|
|
Term
|
Definition
• Largest commissure in the brain
• Allows right and left cerebral hemispheres to communicate with each other
• Arches around the anterior horn of the lateral ventricles |
|
|
Term
|
Definition
• Vestibulo-ocular reflex/doll’s eye reflex
• Head righting and tonic neck reflexes |
|
|
Term
| Vestibulo-ocular reflexes |
|
Definition
(Doll's Eye)
• Purpose is to keep a stable image on the retina as the head moves.
Eyes move in opposite direction to the head.
• We’ll discuss more about the underlying mechanism in the next unit, when we cover vision. |
|
|
Term
| Head righting and tonic neck reflexes |
|
Definition
Eyes adjust to head movement
Head moves in a protective state
• Some influence limb positioning as well (symmetrical tonic neck reflex and asymmetrical tonic neck reflex). |
|
|
Term
| Vestibular Dysfunction (2) |
|
Definition
• Peripheral nervous system disorders, caused by issues with semicircular canals, utricle, or saccule
• Central nervous system disorders, caused by issues with vestibulocochlear nerve, vestibular nuclei in the brainstem, cerebellum, etc. |
|
|
Term
| Vestibular Dysfunction Common Symptoms |
|
Definition
• Nystagmus
• Tinnitus
• Vertigo
• Loss of balance and (possibly) falls
• Using a wide base of support • Sweating, nausea, vomiting
• Hearing loss |
|
|
Term
| Benign Paroxysmal Positional Vertigo (BPPV) |
|
Definition
• Caused when otoconia detach from the utricular and are displaced into semicircular canal
• Usually the posterior canal is affected. Horizontal canal is next most common. Anterior is uncommon
• Treated by placing the person into specific positions to reposition the
displaced otoconia back into the utricle (called the Epley maneuver) |
|
|
Term
|
Definition
• Peripheral nervous system syndrome in which both auditory and vestibular functions are disrupted.
• Symptoms are episodic and vary in frequency and intensity
• Symptoms include: intense and abrupt episodes of vertigo, hearing loss, tinnitus, feeling of “fullness” in the ear, nausea, vomiting, nystagmus
- Don't have drainage of the endolymph, causing rupture of membraneous labyrinth |
|
|
Term
|
Definition
Mismatch of visual and vestibular systems
• Symptoms include vertigo, nausea, vomiting, lowered blood pressure, tachycardia, sweating
• Can be decreased with habituation, obtaining a match between vision and vestibular systems, and/or medication |
|
|
Term
|
Definition
• The retina is part of the CNS – a visible extension of the brain!
• The optic nerve (CN II) has a meningeal cover and the subarachnoid space surrounding it is continuous with the subarachnoid space that surrounds the brain.
• As a result, when there is trauma to the brain and intracranial pressure increases, the optic disk swells.
• This bulging is called papilledema |
|
|
Term
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Definition
• Pupil controls amount of light entering the eye
- nothing to do with focus. Focus is from shape of cornea and shape of lens.
• Cornea and lens focus light on retina
- Zone fibers and ciliary muscles change lens shape |
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Term
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Definition
| Specialized for peripheral vision - respond best to movement and can function in dim light |
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Term
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Definition
| Best in bright light, for color and visual acuity. |
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Term
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Definition
| • When photoreceptors hit by light, they change shape and activate a 2nd messenger system. That ultimately opens ion channels to allow depolarization and action potentials to be sent. |
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Term
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Definition
| Present in the retina – they are important for circadian rhythm. |
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Term
| Stimulation of photoreceptors |
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Definition
1. Light enters eye.
2. Stimulates photoreceptors.
3. Action potential generated.
4. Neural signal exits the eye.
5. Neural signal travels along the optic nerve. |
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Term
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Definition
• Irregularity in curvature of cornea
• Causes blurriness
• Treated with glasses or surgery |
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Term
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Definition
• Far sightedness
• Eye is either shorter than normal or cornea is not curved enough
• Either way, image tries to focus on a point behind the retina and appears blurry
• Corrected with glasses or surgery |
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Term
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Definition
• Near sightedness
• Either eye is longer than normal or cornea is curved too much
• Either way, image is focused in front of the retina and appears blurry
• Corrected with glasses or surgery |
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Term
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Definition
• Related to aging
• Accommodation problem
• Lens is less flexible with age and cannot change as easily, especially when focusing on close objects (when needs to get rounder)
• Treated with reading glasses |
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Term
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Definition
• Progressive opacity of the lens of the eye
• Develops gradually over time. All people will develop some cloudiness of the lens as they age
• Risk factors include age, smoking, exposure to ultraviolet light, malnutrition |
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Term
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Definition
• Progressive loss of vision – causes myopia
• Glare sensitivity with bright lights at night or during the day
• Painless |
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Term
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Definition
• Surgical extraction and lens replacement
• Very successful surgery – about 95% have excellent vision post surgery |
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Term
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Definition
• Increase in intraocular pressure by either increased production or impaired outflow of aqueous fluid - damages optic nerve
(2)
• Angle-Closure • Open-Angle |
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Term
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Definition
Medical Emergency (Rare, 10%)
• Pupil margin of the anterior angle pushes against the lens and blocks the flow of the aqueous fluid into the anterior chamber
• Symptoms include:
• Redness
• Pain in or around the eye
• Severe headache
• Nausea and vomiting
• Blurred vision |
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Term
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Definition
• Onset is very gradual and asymptomatic until late in the disease, affects both eyes
• Peripheral vision is lost – can eventually cause blindness
- pressure increase and damage to CNS, results in tunnel vision |
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Term
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Definition
• The retina separates from the retinal pigment epithelium on the back of the eye.
• MEDICAL EMERGENCY! Without early treatment, vision loss can occur and be permanent
• Symptoms:
• Sudden increase in floaters
• Flashes of light, especially in the periphery
• Block in visual field, like a “curtain” dropping over visual field |
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Term
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Definition
| tear in retina allows fluid under retina, causing it to detach – most common. Can be caused by trauma or vitreous adhering to retina and pulling |
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Term
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Definition
| scar tissue on the retina contracts and pulls the retina off the retinal pigment epithelium |
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Term
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Definition
| usually caused by retinal disease. Fluid leaks under the retina, but there are no retinal tears. |
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Term
| Retinal Detachment – Risk Factors |
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Definition
• Age – more common in people > 40
• Extreme myopia
• h/o retinal detachment
• Family h/o retinal detachment
• Cataract surgery
• Other eye diseases
• Eye injury |
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Term
| Retinal Detachment - Treatment |
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Definition
| • Small tears or detachment – area around tear is treated with laser surgery to “weld” the retina to the epithelium. |
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Term
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Definition
| band put around eye to push back of eye onto the retina. Combined with repair with laser or freezing. |
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Term
| Retinal Detachment Large tear or detachment |
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Definition
| vitrectomy is used to remove the fluid in the center of the eye. Laser is used to fuse the retina to the epithelium and then the eye is filled with gas or saline. Gradually, the eye makes more fluid to replace the gas. |
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Term
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Definition
• Causes degeneration of photoreceptor cells in the retina,
results in progressive vision loss
• Usually first diagnosed in childhood, adolescence, or young adulthood. |
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Term
| Retinitis Pigmentosa - Symptoms |
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Definition
• Early stages – for most people, loss of rods resulting in night blindness – can’t adjust to dark or dimly lit areas
• Middle stages – with more loss of rods, start to lose peripheral vision – usually maintain some central vision |
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Term
| Age-Related Macular Degeneration (ARMD) |
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Definition
• Leading cause of low vision
• Two types: dry and wet
• Affects macula only |
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Term
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Definition
| • Age-Related Eye Disease Study (AREDS) dietary supplement can slow progression of dry ARMD |
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Term
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Definition
• Abnormal blood vessels grow under and into the retina, specifically the macula.
• 10% of cases
• Onset can follow dry ARMD
• Distortion is one of first symptoms. If someone reports distortion, must see ophthalmologist ASAP |
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Term
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Definition
• Laser surgery to destroy the new blood vessels (also damages some
of the surrounding tissue).
• Photodynamic therapy: verteporfin injected into arm travels
throughout body, including to eye. MD shines light in eye to activate the drug, which destroys the new blood vessels, but not the surrounding tissue.
• Injections in the eye which block growth factor and stop new blood vessel development. |
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Term
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Definition
• Eye disease caused by diabetes
• Stages:
• Nonproliferative/Background
• Proliferative
• Macular edema can occur at any point |
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Term
| Nonproliferative/Background diabetic retinopathy |
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Definition
• Abnormalities develop in small blood vessels in the retina leading to loss of pericytes which have contractile properties
• Leads to capillary dilation and weakening of vessel walls ultimately causing microaneurysms
• Non-dilated capillaries receive less blood supply until they carry no blood at all – leads to areas of the retina that are not receiving any blood
- Hemorrhage, retinal detachment |
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Term
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Definition
• Eye disease caused by diabetes
• Stages:
• Nonproliferative/Background
• Proliferative
• Macular edema can occur at any point |
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Term
| Nonproliferative/Background diabetic retinopathy |
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Definition
• Abnormalities develop in small blood vessels in the retina leading to loss of pericytes which have contractile properties
• Leads to capillary dilation and weakening of vessel walls ultimately causing microaneurysms
• Non-dilated capillaries receive less blood supply until they carry no blood at all – leads to areas of the retina that are not receiving any blood
• Other symptoms include hemorrhage, exudates (excess fluid), cotton-wool spots |
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Term
| Proliferative diabetic retinopathy |
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Definition
• As background diabetic retinopathy progresses, less oxygen reaches retinal cells. To attempt overcoming this, new blood vessels form on the surface of the retina.
• These blood vessels are not effective in delivering oxygen however, and often break leading to hemorrhage into the vitreous gel of the eye, which can cause “floaters”
• Abnormal blood vessels can also lead to traction retinal detachment |
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Term
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Definition
• Can occur at any stage of diabetic retinopathy
• Fluid leaks into the macula
• Edema damages cells by depriving them of oxygen • Leading cause of blindness in people with diabetes • Major symptom is blurred vision |
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Term
| Symptoms of diabetic retinopathy |
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Definition
• Because retinopathy can affect any portion of the retina, there is not a predictable pattern of visual loss
• Symptoms may also fluctuate with changes in blood glucose
• People with nonproliferative/background diabetic
retinopathy may have no symptoms |
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Term
| Treatment of diabetic retinopathy |
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Definition
• Regular eye examinations
• Close control of blood glucose and blood pressure
• Laser therapy to treat microaneurysms and to stop the growth of abnormal blood vessels |
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Term
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Definition
“What” pathway AKA “vision for perception”
• Contains parvocellular.
• Travels along the inferior longitudinal fasciculus to the
temporal lobe.
• Important for object identification and visual memory
• Seems to be important too for determining spatial relationships between objects
• This information is more conscious |
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Term
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Definition
“Where” or “How” pathway AKA “vision for
action”
Contains magnocellular information
• Travels along the superior longitudinal fasciculus to the
posterior parietal lobe
• Important for determining spatial layout of the visual scene and providing information that can guide movement and direct attention
• Seems to be important for determining the spatial relationship between objects and the viewer
• This information is more unconscious |
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Term
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Definition
• Movement of eyes essential to get information focused on most sensitive part of retina (fovea)
• Saccades
• Can be quick – when eyes jump to a target
• Can be slow (smooth pursuits) – when follow a target moving with eyes
– can’t do this without a target. |
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Term
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Definition
• Conjugate – eyes move together
• Convergence – eyes move toward each other (as in reading or looking at a target near face)
• Divergence – eyes move away from each other (when looking at something in the distance) |
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Term
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Definition
• Can be quick – when eyes jump to a target
• Can be slow (smooth pursuits) – when follow a target moving with eyes – can’t do this without a target. |
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Term
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Definition
• Superior rectus, inferior rectus, medial rectus, lateral rectus
• Inferior oblique, superior oblique |
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Term
| Three cranial nerves (motor nerves) Eye Movement |
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Definition
• III: oculomotor
• IV: trochlear
• VI: abducens |
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Term
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Definition
(Important for accommodation)
• Levator palpebrae superioris: Lifts eyelid
• Superior rectus: pupil up (and a bit out)
• Medial rectus: pupil medial
• Inferior rectus: pupil down (and a bit out)
• Inferior oblique: pupil up and in
• Pupillary sphincter: constricts pupil
• Ciliary bodies: changes shape of lens |
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Term
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Definition
Superior Oblique: pupil down and in
SO4 |
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Term
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Definition
• LR6
• Lateral rectus: pupil lateral |
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Term
| Damage to cranial nerves: III |
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Definition
| ptosis, “down and out” positioning, diplopia, loss of pupillary reflex (reaction to light) |
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Term
| Damage to cranial nerves: IV |
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Definition
| cannot move eye down and in, double vision when looking down and medially, difficulty with reading and stairs |
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Term
| Damage to cranial nerves: VI |
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Definition
| cannot move eye out, double vision when trying to look toward that lateral rectus muscle |
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Term
| Other contributors to eye movement |
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Definition
• Paramedian pontine reticular formation (PPRF) – important for conjugate gaze in horizontal plane
• Superior colliculi – important for involuntary saccades
• Rostral interstitial nucleus – important for conjugate gaze in vertical plane
• Medial longitudinal fasciculus - connects between cranial nerve nuclei travel here |
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Term
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Definition
| • Especially important for smooth pursuits |
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Term
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Definition
| • Frontal eye fields very important. Other areas contribute as well |
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Term
| Damage to the frontal eye field |
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Definition
| deficit in voluntary gaze contralaterally |
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Term
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Definition
| inability to look ipsilaterally |
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Term
| Damage to the medial longitudinal fasciculus |
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Definition
inability to
direct contralateral eye medially – interrupts conjugate gaze |
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Term
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Definition
• Causes can vary: strabismus (malalignment of eyes), one eye having worse acuity (through myopia, hyperopia, astigmatism, cataract)
• Results in one eye having stronger neural signaling to brain than the other. |
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Term
| Involvement of vestibular system and Eye Movement |
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Definition
• Visual and vestibular system work together to allow image to be fixed on retina during head movement
• One of the most important reflexes is the vestibulo-ocular reflex. |
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Term
| Vestibulo-ocular reflex (VOR) |
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Definition
• Stabilizes image on retina during fast eye movements. Input is not visual – it is from the vestibular apparatus
• As head turns, causes otoliths of the utricle/saccule AND/OR fluid in semicircular canals to move – signal sent via vestibular nuclei to C.N. III, VI, VI (whichever appropriate)
• Results in eyes moving in opposite direction to head movement (III and VI if horizontal movement; combination in other directions)
• If want to look in same direction as head turn, VOR suppressed by cerebellar flocculonodular lobe and brainstem |
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