Exam 4 Flashcards
Motor apraxia
Difficulty in coordinating bimanual or fractionated movements that is NOT due to muscle weakness/ paralysis (commonly in SMA)
Motor aphasia
Word finding language deficit (commonly Broca’s area)
Stria terminalis connects what structures
Amygdala to hypothalamus and septal region
In a coronal section, what’s a landmark for the level at which the genu of the internal capsule is show?
Interventricular foramen
Describe the ventral amygdalofugal pathway (VAFP)
Connects the amygdala to the lateral hypothalamus and the thalamus (dorsomedial nucleus), emotion cortex, ventral striatum and pallidum, and brainstem nuclei
Travels through the basal forebrain region
EMOTION CORTEX LESIONS
Orbitofrontal:
Anterior cingulate:
Ventromedial cortex:
- marked personality changes (impulsivity, explosiveness, tactlessness, lability, lack of interpersonal sensitivity)
- akinetic mutism, profound apathy, abulia, immobility
- psychopathy (absence of emotion, empathy, remorsefulness)
Major output to septal nuclei and mammillary of the hypothalamus is through the
Fornix
What part of the thalamus receives fibers from the mammillothalamic tract?
What structures does it project to?
- Anterior nucleus
2. Cingulate gyrus via anterior limb of internal capsule
Wernicke-Korsakoff syndrome
- cause?
- atrophy/infarct to?
- effects?
- due to severe thiamine deficiency (B-1); most commonly due to alcohol abuse
- atrophy/infarct of the dorsomedial nucleus of thalamus
- DM nucleus functions in the declarative memory system
What are 4 aspects of long term potentiation in declarative memory
- Tetanic stimulation is required
- Strong tetanic stimulus is required
- LTP is associative
- The NMDA receptor is required
- Calcium influx is required
Limbic lobes (4)
o Cingulate gyrus
o Parahippocampal gyrus
o Ventromedial prefrontal cortex
o Orbitofrontal cortex
Difference b/w mood and affect
o Mood – underlying baseline emotional tone
• Analogous to muscle tone
• Can’t be observed
o Affect – Transient outward sign
• Observed emotional expression in a patient
What is the UMN for the ANS?
Hypothalamus
List 3 tasks of the amygdala
The amygdala is the coordinating center for emotional state that
(1) assigns an emotional grade (VALENCE) to sensory input and/or thoughts;
(2) sends signals to emotion cortex for conscious awareness of emotional feelings; and,
(3) sends signals to emotional expression centers (hypothalamus, emotion basal ganglia) for emotional behavior
Kluver-Bucy Syndrome
- cause
- signs/sxs
- bilateral lesion of medial temporal lobes, including the amygdala and uncus
- may exhibit docile behavior and flattened affect, indiscriminate hypersexuality, hyperorality (exploration of objects using one’s mouth) and hyperphagia (excessive eating), visual agnosia and excessive attention to visual stimuli
Urbach-Wiethe disease
- calcification lesions of the amygdala (congenital)
- won’t be able to read emotion in people’s faces
Medial forebrain bundle
- travels through lateral hypothalamus and brainstem reticular formation
- connects the emotion centers in the forebrain w/ each other and w/ brainstem nuclei
- continuous w/ descending hypothalamic fibers that descend to preganglionic sympathetic and parasympathetic neurons
Cholinergic cell groups
- location
- fx
- nucleus basalis
- memory, attention, sleep/wake cycle
Serotonergic cell groups
- location
- fx
- raphe nuclei of rostral brainstem
- mood
Noradrenergic cell groups
- location
- fx
- locus ceruleus
- activate entire cortex for increased arousal and vigilance
Dopaminergic projection for emotion
- 2 pathways
- fx
VTA to
- mesolimbic pathway
- subcortical structures - Mesocortical pathways
- particularly prefrontal cortex
Activate entire cortex for increased arousal and vigilance
Describe the components of the limbic basal ganglia and function
Fx -> selection of MOTOR programs essential for survival
Ventral striatum + ventral pallidum
Nucleus accumbens is the INPUT
• Amygdala to NA via the stria terminalis
• Where the caudate and putamen are connected ventrally
Ventral pallidum is the OUTPUT
• Projects to the DM nucleus of thalamus
List the pathway to activate motor neurons for emotional response
receptors recording state of environment -> amygdala (emotional grading) -> nucleus accumbens -> ventral pallidum -> DM of thalamus -> emotional cortex (emotional feelings) -> motor neurons activated for emotional response
UMN for Duchenne smile is through the?
Limbic basal ganglia
Which cranial nerves have parasympathetic function?
III, VII, IX, X
What are the function divisions of the solitary nucleus
What part of the brainstem is it?
- GVAs from VII, IX, X
Cranial portion - taste
Caudal portion - cardiorespiratory nucleus
-axons from IX and X
- Mid/rostral medulla
Ventrolateral medulla
- location
- function
- mid-rostral medulla
- output pathway
-contains CPGs for:
cardiovascular
digestive tract
vomiting
respiratory
Parabrachial nucleus
- location
- function
- Rostral pons
2. modulates ventrolateral medulla activities (e.g. timing of breathing when swallowing)
What coordinates autonomic activity w/ behaviors? Location?
PAG - midbrain
What connects hypothalamus to parasympathetic GVE nuclei in the brainstem
Dorsal longitudinal fasciculus
Describe path of lateral descending hypothalamic fibers
hypothalamus -> brainstem centers (solitary nucleus, ventrolateral nucleus -> preganglionic parasympathetics and parasympathetics in the spinal cord
Pathway for emotional response to odors?
Medial olfactory tract -> septal area (limbic system)
Tract responsible for emotional, endocrine and visceral responses to odors
Lateral olfactory tract -> amygdala (which connects to hypothalamus and septal nuclei
through stria terminalis and ventral amygdalofugal pathway)
Tract of conscious emotions of odors
lateral olfactory tract -> olfactory tubercle (this projects to dorsomedial nucleus of
thalamus, which projects to orbitofrontal cortex)
Tract for conscious recognition of odors
Lateral olfactory tract -> uncus/entorhinal cortex/piriform cortex
Primary afferents for taste
CN VII - anterior 2/3 of tongue
CN IX - posterior 1/3
CN X - epiglottis region
1st, 2nd and 3rd order neurons for taste pathway
VII, XI, X -> solitary nucleus (through solitary tract)
Solitary nucleus -> parvocellular VPM through central tegmental tract
VPM -> posterior limb internal capsule -> insular cortex + gustatory region of postcentral gyrus
What is the fx of the area postrema? location?
-mid medulla
- Activated by toxins in CSF or blood which directs the emetic center
- Another route than through the solitary nucleus
Bilateral ablation of VL nucleus or upper cervical cord results in
Respiratory arrest/apnea
Parabrachial nucleus
- location
- fx
- Rostral pons
2a) apneustic center - stimulates inhalation
b) pneumotaxic center - inhibits apneustic center
Lesion site for ataxic breathing
b/w pons and medulla - no pontine control of VL medulla
Describe apneusis
Damage to pneumotaxic center
prolonged inhalation followed by patient hold his breath
Cheyne-Stokes respiration
-seen in bilateral thalamic compressions
alternating deep breathing and apnea
Describe the autonomic innervation to the bladder
External urethral sphincter -> somatic neurons
Internal - sympathetic
Detrusor muscle - parasympathetic
Describe the sxs seen with sensory paralytic bladder and the cause?
-can consciously void but tend to overstretch bladder b/c don’t realize it’s getting full
- damage to sensory peripheral neurons
- e.g. tabes dorsalis
Where are circumventricular organs found and what do they do?
Which one is involved in monitoring blood for toxins and triggering the vomiting reflex
- walls of 3rd and 4th ventricles where BBB is lacking
- monitor physiologic states
- area postrema -> walls of caudal 4th ventricle
What are the nuclei in the anterior region of hypothalamus? (PSPS)
preoptic
supraoptic
paraventricular
suprachiasmatic
Define poikilothermia and cause
- body temperature fluctuates with ambient temperature
- Bilateral anterior hypothalamic lesions can injure or destroy the circuitry for regulation of body temperature, because of the loss of the anterior heat releasing center and fibers to the posterior heat production center.
kallman’s syndrome
- cause
- signs
- failure of preoptic nuclei migration to hypothalamus
- hypogonadism and anosmia
Bilateral lesions of the anterior region of the hypothalamus or, more commonly, injury to the infundibular stalk of the hypophysis, can result in?
Diabetes insipidus - polyuria and polydipsia
Middle hypothalamus
- nuclei
- fx
- Arcuate nuclei
- makes DA, TRH, GRH, GnRH
- release of factors to regulate hormone balance needed for body development, growth, and favorable energy - VMN
- satiety center
- links energy requirement to food seeking behavior
- connected to emotional centers and indirectly to somatic/visceral centers
Neurons in posterior hypothalamus?
- mammillary
- Posterior
- tuberomammillary - lateral zone
Fx of posterior nucleus of thalamus
output through?
heat conservation/production
- output signals directly (or via the PVN) to stimulate sympathetic motor neurons for cutaneous vasoconstriction (heat conservation)
- output signals through the MFB and reticular formation to somatic motor neurons for heat production by shivering.
Fx of tuberomammillary nucleus
NT produced?
Arousal and sleep/wake regulation
contains the only CNS histaminergic neurons
How does the hypothalamus influence the anterior pituitary?
Parvocellular neurons in the arcuate, preoptic and paraventricular nuclei -> secretion of releasing and inhibiting hormones into the median eminence
Supragranular division of cortex layers
- layers included
- function
- Layers I - III
- involved in inter-cortical communication
Layer III is the primary source of cortico-cortal outflow
Which cortex layer is is the primary sensory input?
Which division?
where is thickest?
Layer IV - thickest in primary sensory areas
receiving input from the thalamus
granular division
Infragranular division of cortex of cortex layers
- layers included
- function
- where is thickest
- layers V - primary output to extra/subcortical areas (corticospinal/bulbar tract)
- thickest in primary motor cortex
Layer VI
- fusiform cells
- cortex to thalamus
Specific/targeted afferents to the cortex end up in which layer?
IV
Association/commissural afferents
- difference
- function
function -> communication
difference
- association -> w/in the same hemisphere
- commissural -> across the midline to contralateral hemisphere
3 long association fibers
- Superior longitudinal (arcuate) fasciculus
- anterior to posterior connections
- arcuate: frontal to temporal (including Broca’s to Wernicke’s) - Uncinate fasciculus
- orbitofrontal cortex to anterior temporal cortex - Cingulum
interconnects limbic lobe areas
2 major cortical commisures
- Corpus callosum
- interconnects opposite contralateral hemispheres - Anterior commissure
- interconnects anterior temporal cortices
Define agnosia
deficits in RECOGNITION
“Not knowing” An inability to recognize, attach meaning to or understand the meaning of perceived stimuli, with sensory capabilities intact.
Stereoagnosia
- definition
- cause
- can’t recognize objects by touch alone
- lesion in S-II
What is the fx of the posterior association cortex?
integrates sensory input
• Recognition of objects + people.
• Form an understanding of space and our place in it
• Recognize and understand complex symbols as a learned language and communicate via this language. One of the unique aspects of human brains
Compare ventral and dorsal pathways for visual processing
- Ventral -> temporal lobe
- from parvocellular visual system
- what pathway (details and color of image) - Dorsal pathway
- magnocellular
- where path
- large, moving objects
Visual object agnosia
- definition
- lesion site
- inability to recognize objects from visual input
- bilateral lesions of inferior temporal cortex
Prosopagnosia
- definition
- lesion site
- inability to recognize familiar faces
- most often w/ lesion in non-dominant hemisphere
Sensory apraxia
- lesion site
- similar to what other apraxia?
bilateral lesions of superior parietal areas
similar to motor apraxia and differences are very subtle (hard to differentiate b/w the 2)
Balint’s syndrome
- lesion site
- sxs
- imaging
-lesion -> bilateral posterior parietal cortex
sxs
-optic ataxia -> can’t use vision to coordinate actions
- ocular ataxia -> fixated on the center
- simultanagnosia -> can’t recognize more than one object shown at the same time or integrate them into a whole
imaging -> shrinking of sulci and widening of gyri
Gerstmann’s syndrome lesion site
Dominant parietal lobe angular gyrus
Dominant vs non-dominant lesions
- depression or euphoria?
- exceptions?
Dominant - depression
-exception -> Wernicke’s aphasia
Non-dominant - depression
Contralateral neglect
-lesion
non-dominant PPC (usually right)
A person with intact language but can’t appreciate music has lesion in the?
non-dominant hemisphere
DL-PFC lesion’s effect on mood
Abulia - without will
NO RESPONSE TO ANTIDEPRESSANTS
Neurogenesis gradually becomes restricted to the?
ventricular and subventricular layers
2 ways neural migration occurs
- Radial migration
- neurons move along radial glia
- hop off using reelin and other proteins
- radial glia eventually become astrocytes - Tangential migration
- neuroblasts migrate in channels
- in adults -> make olfactory interneurons via rostral migratory stream
Most common finding in disorder of neuronal development?
seizures
Lissencephaly
- description
- most common cause
- often occurs with?
Compare to Lissencephaly w/ cerebellar hypoplasia
- smoothened surface of cerebral cortex
- mostly due to thickened cortex
- mutation in doublecortin gene
- lack of neuronal migration from ventricular zone
- often occurs w/ heterotopia - LCH
- mutation in reelin
- neurons detach from radial glia
Describe heterotopia
- abnormal accumulation of cortical neurons
- seizures w/ mild mental retardation
- due to issue w/ neuronal cell migration
Conduction aphasia
- lesion site
- effects
lesion in arcuate fasciculus -> connects Broca’s to Wernicke’s
Effects
- deficit in auditory-verbal short term memory
- can understand fine
- paraphasic errors -> substituting sounds or words
- poor sentence repetition
Damage to which gyrus is associated with dyslexia?
Angular gyrus
Give the deficit for the following lesion site
- blocking transmission of info from right occipital cortex to left angular gyrus
- lesion in supramarginal gyrus
- alexia - can’t read
- agraphia - can’t write
these are often seen together due to proximity
Most severe deficit with anomic aphasia
difficulty naming stuff most severe
fluent speech with pauses
What’s always spared with transcortical aphasia?
repitition
What’s the lesion site?
- transcortical motor aphasia
- transcortical sensory aphasia
- TMA - anterior or superior to Broca’s
2. TSA - lesion at left temporal-occipital-parietal jx behind Wernicke’s
What’s seen with a right frontal lobe lesions? (Area equivalent to Broca’s)
- Tangentiality - digression from one topic to another
2. Confabulation - false memories, perceptions or beliefs about self or environment
What’s seen with a right temporal lobe lesion
- difficulties recognizing familiar melodies
- time sense rhythm disrupted
- ability to remember musical tunes is impaired
Which part of the cortex receives declarative memory?
Episodic?
Procedural?
Declarative - inferolateral cortex
Episodic - medial cortex
Procedural - basal ganglia and cerebellum
