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What results from damage to the descending lateral motor system in the spinal cord?
- inability to form voluntary, goal-oriented movements with distal limbs (contralateral)
- does not affect postural control
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Damage to which part of the brainstem generally results in ataxia?
cerebellar peduncles
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What are the general functions of the midbrain?
eye movt; pupillary light reflex (CN3); orienting, ”consciousness”
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What are the general functions of the pons?
sensory info from face (CN5); control of facial (CN7) and chewing (CN5) mm, lateral eye movt (CN6); corneal blink reflex (CN5,7)
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What are the general functions of the medulla?
gag reflex (CN 9,10); swallowing, tongue movt (CN 12); regulation of CVS, respiratory and visceral activity
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What is the cause of multiple sclerosis and what are its symptoms?
- cause: demyelination of CNS; axonal loss
- sx: optic neuritis, weakness, spasticity, ataxia, tremor, cognitive damage
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What are the patterns of sensory loss with damage to the brain, brainstem, and spinal cord?
- brain: hemisensory; unilateral
- brainstem: hemisensory; crossed face-body; unilateral
- spinal cord: sensory loss at level of lesion; bilateral; head okay
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Which diseases primarily affect UMN only?
primary lateral sclerosis
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Which diseases primarily affect LMN only?
- spinal muscular atrophy
- viral infections (e.g. polio, HIV, etc.)
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Which diseases primarily affect UMN and LMN concurrently?
amyotrophic lateral sclerosis (ALS)
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What are some examples of association bundles in the brain?
- intrahemispheric bundles
- cingulum
- superior longitudinal fasciculus (frontal, temporal, parietal, occipital lobes) (includes arcuate fasciculus)
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What are some examples of projection fibers?
- corticospinal
- corticobulbuar
- corticopontine
- corticostriate
- corticothalamic
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What are the components and locations of the primary sensory cortex?
- somatosensory cortex: postcentral gyrus
- visual cortex: banks of calcarine fissure
- auditory cortex: transverse temporal gyri
- olfactory cortex: perpyriform cortex at junction of orbitofrontal and temporal lobes
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What are the components and locations of the primary motor cortex?
primary motor cortex = precentral gyrus
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Where is the premotor cortex?
- posterior part of superior and middle frontal gyri (e.g. frontal eye fields)
- sometimes included as part of the association cortex
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Which area of the brain has the highest level of dopamine innervation?
prefrontal cortex
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What are some general features of the prefrontal cortex?
- highest amount of dopamine innervation in brain
- heteromodal, higher order association cortex
- connected with amygdala (directly and via MD nucleus)
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What are some general functions of the prefrontal cortex?
- restraint: inhibition of inappropriate behavior
- initiative: motivation to pursue productive activity
- order: capacity to perform meaningful sequences of motor activity
- working memory
- mental flexibility
- personality
- selective attention
- decision-making
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What generally results from lesions to the prefrontal cortex?
- impaired executive function
- inappropriate jocularity
- confabulation
- environmental dependency
- perseveration
- impersistence
- incontinence
- problems with abstract reasoning and judgment
- depression/mania
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What results from a lesion to the orbito-frontal part of the prefrontal cortex?
- apathetic
- lifeless
- abulic state
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What results from a lesion to the dorso-lateral part of the prefrontal cortex?
- impulsive
- disinhibited behavior
- poor judgment
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How does damage to the left prefrontal cortex differ from damage to right prefrontal cortex?
- damage to the left prefrontal cortex --> depression
- damage to right prefrontal cortex --> mania
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How do schizophrenia and prefrontal cortex relate?
damage to prefrontal cortex or abnormalities in dopaminergic circuits may relate to schizophrenia
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What are some general features of the temporal lobe?
- contains continuation from primary visual cortex of the "what" stream (i.e. object identification)
- bidirectionally linked with hippocampus
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What are some general functions of the temporal lobe?
- contains continuation from primary visual cortex of the "what" stream (i.e. object identification)
- learning
- retention
- relearning of visual form discriminations
- consolidation of memories
- some olfactory function
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What generally results from damage to the temporal lobe?
- visual agnosias
- (bilateral) Kluver-Bucy syndrome
- memory problems
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What generally results from electrical stimulation to the temporal lobe?
- sensations of deja vue, religious or mystical phenomena
- strange dream-like experience
- olfactory hallucinations
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What are some general functions of the parietal lobe?
- spatial analysis (especially non-dominant hemisphere)
- contains continuation from primary visual cortex of the "where" stream (i.e. localization of object)
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What genreally results from lesions to the parietal cortex?
- anosognosia (lack of awareness of illness or condition)
- hemi-attention in one or more sensory modalities
- abnormal internal representation of spatial details
- astereognosis (inability to identify an object by touch without visual input)
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What is the function of the occipital association cortex?
higher order visual areas
dorsally: "where" stream concerned with location/movement of visual objects; spatial relationships (projects to parietal lobe)
ventrally: "what" stream concerned with identification of objects (projects to temporal lobe)
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What generally results from legions to the occipital lobe?
- visual agnosias: prosopagnosia (damage to fusiform gyri bilaterally)
- achromatopsia (inability to perceive color)
seizures in occipito-temporal cortex can produce complex visual hallucinations
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What are some general (lateralized) functions of the left cerebral hemisphere?
- handedness, eyeness, speech
- language (verbal)
- concepts (ideas)
- analytic (logical)
- sequential (details)
- arithmetic (linear)
- immediate verbal memory (word recall)
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What are some general (lateralized) functions of the non-dominant (right) cerebral hemisphere?
- visuo-spatial tasks, emotional significance of stimuli, spatial attention, music
- musical (nonverbal)
- pictures (pattern recognition)
- synthetic (artistic)
- holistic (big picture)
- geometric (spatial)
- immediate nonverbal memory (visual or melodic recall)
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Apraxia (loss of language function, loss of detailed analytic ability, loss of complex motor programming) results from damage to which cerebral hemisphere?
- dominant cerebral hemisphere
- (generally left hemisphere in most people)
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Which cortical layers receive input from other cortex?
layers II, III
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Which cortical layers send outputs to other cortex?
layers II, III, V, VI
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Which cortical layers receive afferents from thalamus?
layers III, IV
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Which cortical layers send outputs to thalamus?
Layer VI
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In which cortical layer do projection fibers (corticostriatal, corticopontine, corticobulbar, corticospinal, corticothalamic) originate?
- layer V: corticostriatal, corticopontine, corticobulbar, corticospinal
- layer VI: corticothalamic
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What is the definition of epilepsy?
abnormal, excessive, paroxysmal (sudden and transient), synchronous discharge of a population of neurons, with a change in behavior and/or perception
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What are the 4 main types of general seizures?
- tonic-clonic (grand mal)
- absence (petit mal)
- myoclonic: twitches, jerks
- atonic: sudden loss of muscle strength
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What part of the brain is the most common origination point for focal seizures?
temporal cortex
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What are the 4 stages of an "epileptic's life"?
- aura: brief period at start of some seizures; patient remembers brief period; can give clues to seizure origination site (e.g. weird smell)
- ictus: sequence of events that form seizure itself
- post-ictal: immediately after seizure; symptoms during this period will vary depending on type/severity of seizure
- inter-ictal: all the rest of epileptics life
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What is the general progression of a focal seizure?
- originates in one part of cortex (esp. temporal)
- partial (focal) seizure (aura)
- cortex interacts with deep brain nuclei
- seizure spreads (generalization)
- post-ictal period
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What is the fundamental cause of an interictal epileptiform discharge?
- paroxysmal depolarizing shift
- channelopathies
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What is cerebral palsy and what are its clinical features?
- cerebral palsy = static encephalopathy = syndrome of delayed and abnormal motor development due to dysfunction of the CNS
- clinical features:
- static encephalopathy that does not progress
- spastic weakness
- sometimes involuntary movements
- may also have epilepsy, cognitive impairment
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What are some potential causes of cerebral palsy?
- insults to developing nervous system
- prematurity
- neonatal or perinatal hypoxia
- meningitis
- hemorrhage
- trauma
- *most have no identifiable cause*
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What are some clinical features of intellecutal disability (mental retardation)?
- sub-average intellectual abilities (IQ less than 70)
- limitations in adaptive functioning
- non-progressive syndrome (vs. cognitive degenerative disorders that may lead to dementia)
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What are the (4) classic clinical features of hypotonia in children/infants? What are some additional "clues" for differential diagnosis?
- paucity of voluntary movements
- unusual postures
- decreased resistance to passive movement of a joint
- increased joint mobility
abnormal deep tendon reflexes (UMN vs. LMN/Peripheral/NMJ)
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What are the 2 basic clinical patterns of hypotonia in children?
- paralytic: floppy, weak --> peripheral nervous system disease
- non-paralytic: flppy, adequate muscle strength --> central nervous system disease
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Which is false about the thalamus?
a. the thalamus projects primarily to the cerebral cortex
b. all sensory pathways, except olfactory, synapse in the thalamus
c. many thalamo-cortical projections are reciprocal
d. there are no points of contact between the thalami in either hemisphere
- d. there are no points of contact between the thalami in either hemisphere
- (interthalamic adhesion)
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What structure lies between the posterior lobes of the thalami?
pineal gland
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What are the sensory nuclei of the thalamus?
- ventral posterior medial (VPM): somatosensory from face
- ventral posterior lateral (VPL): somatosensory from body
- lateral geniculate nucleus (LGN): visual
- medial geniculate nucleus (MGN): auditory
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What are the motor nuclei of the thalamus?
- ventral anterior (VA): basal ganglia, cerebellum
- ventral lateral (VL): cerebellum, basal ganglia
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What are the association nuclei of the thalamus?
- lateral dorsal (LD)
- lateral posterior (LP)
- pulvinar (P)
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What are the (7) major types of nuclei in the thalamus?
- sensory
- motor
- association
- limbic
- intralaminar (e.g. centromedian)
- midline
- reticular
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What are the limbic nuclei of the thalamus?
- anterior (A): mammillary bodies
- medial dorsal (MD): hypothalamus
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What separates the thalamus into anterior, medial, and lateral portions?
internal medullary lamina
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Through which structure do thalamic outputs project to the cortex?
internal capsule
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What are the general inputs and outputs of the motor thalamic nuclei (VL, VA)?
- inputs: globus pallidus (VA); cerebellum (VL)
- outputs: premotor,supplementary motor areas (VA); motor, premotor areas (VL)
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What behavior is the intralaminar nuclei of the thalamus involved in?
sleep-wake cycles
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Which thalamic nuclei projects to the cingulate gyrus?
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Which thalamic nuclei projects to the prefrontal cortex?
mediodorsal
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Which thalamic nuclei project to the superior and middle frontal gyri?
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Which thalamic nuclei project to the parietal, occipital, and temporal lobes?
pulvinar
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Which thalamic nuclei project to the parietal lobe?
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Which thalamic nuclei project to the postcentral gyrus?
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What are some thalamic projections through the internal capsule and where are they located?
- thalamic radiations (i.e. thalamo-cortical fibers): both limbs
- anterior limb: anterior/medial thalamic nuclei --> frontal lobe
- posterior limb: ventral thalamic nuclei --> motor and sensory gyri
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Where is the retrolenticular radiation of the thalamus and what does it connect?
- retrolenticular radiation is behind the lentiform nucleus (i.e. posterior margin of posterior limb of internal capsule)
- connect: LGN --> visual cortex
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Where is the sublenticular radiation of the thalamus and what does it connect?
- sublenticular radiation is below the lentiform nucleus
- connects: MGN --> auditory cortex
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What is autism?
- autism is a continuum of disabilities:
- impaired social development
- impaired communicative development
- restricted or repetitive behaviors
assessment is qualitative: relative to developmental level or mental age
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What are some examples of autism spectrum disorders?
- autism
- Asperger's syndrome
- pervasive developmental disorder otherwise not specified (PDD-NOS)
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What are some clinical presentations of autism spectrum disorders?
- deficits in social communication/interaction (lack of social reciprocity, failure to develop/maintain social relationships)
- restricted, repetitive patterns of behaviors, interests, activities
- impaired higher level processing
- mood instability
- imitation impairments
- slowed face learning
- decreased amygdala activity
- enlarged brain
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What are some factors that contribute to positive outcomes of childhood-diagnosed autism?
- degree of MR
- language ability
- neurophysical impairment
- other symptom profiles
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What behavior pattern are mirror neurons associated with?
- imitation behavior
- (inferior frontal gyrus, inferior parietal lobe, superior temporal sulcus, premotor cortex)
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What are some potential causes for the associated enlarged brain in autistic children?
- increased neuronal proliferation
- decreased programmed cell death
- decreased axonal elimination
- decreased dendritic pruning
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What are the stages of sleep and some basic characteristics?
- stage 1: EEG activity low
- stage 2 : EEG activity high
- stage 3/4: EEG activity high
- stage REM: fast, desynchronized rhythms in cortical EEG, autonomic activation, loss of muscle tone, REM
- NREM stages = 80% of sleeping cycle
- full sleep cycle: 4-6 in a night; 90-110 minute intervals
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How does REM sleep compare to NREM sleep?
- NREM:
- first episode = longest in sleep cycle
- REM:
- first episode = shortest in sleep cycle
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What nervous system components are involved in circadian rhythms?
- suprachiasmatic nucleus (SCN, hypothalamus): "central pacemaker" (light cycle)
- DMH (dorsal medial nucleus of hypothalamus)
- supraparaventricular zone (SPZ)
- medial preoptic area (MPO)
- ventrolateral preoptic area (VLPO)
- paraventricular nucleus
- lateral hypothalamic area (LHA)
- arcuate nucleus
- pineal gland: melatonin production (dark cycle)
- adenosine (accumulates during wake to threshold--> promotes sleep)
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What are some key components of the ascending arousal system?
- Ach input to thalamus (dorsal route)
- Ach input to hypothalamus/ventral forebrain (ventral route)
- raphe nuclei
- orexin
- melanin-containing hormone
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What is involved in the ventral portion of the ascending arousal system?
- hypothalamus/ventral forebrain receive orexin (ORX) and melanin-containing hormone (MCH), GABA and Ach
- venterolateral preoptic nucleus (VLPO): active during sleep, contain inhibitory GABA and galanin
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What is involved in the wake side of the "sleep-wake" switch?
- VLPO/eVLPO inhibited by monoaminergic nuclei thus allowing orexin to function
- orexin (ORX) stimulates LC, TMN, and raphe nuclei
- person becomes awake
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What happens with damage to VLPO nuclei?
insomnia
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What are the basic components of the sleep and wake cycles?
- sleep:
- (VLPO) ventrolateral preoptic nuclei --> GABA, galanin
- wake:
- pedunculopontine and laterodorsal tegmental nuclei --> Ach
- locus coeruleus --> noradrenaline
- dorsal raphe --> 5-HT
- tuberomammillary nucleus --> histamine
- basal forebrain --> Ach, GABA
- wake stabilization:
- lateral dorsal hyporhalamus --> hypocretin, orexin (ORX), melanin-containing hormone (MCH)
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