cerebrum Flashcards
unit 2
functions of frontal lobe
- voluntary motor control
- production of language (different than percieving language)
- majority of cognitive functions including:
short term working memeory
attention
behavioral control
executive functions
what are the key motor areas of the frontal lobe?
primary motor cortex (M1)
premotor cortex
supplemental motor area (SMA)
frontal eye fields
broca’s area (left only)
what is the primary motor cortex M1 responsible for?
execution of movement
- upper motor neurons send impulses to brainstem and spinal cord
part of frontal lobe
what is the premotor cortex responsible for?
preparation for and ensory guidance of movement
- inputs from somatosensory areas, thalamus
- outputs to M1 and contralateral premotor cortex
part of frontal lobe
what is hemiparesis?
hemi - half paresis - weakness
weakness, inability to move one side of the body. often caused by lesion of contralateral primary motor cortex or corticospinal tract
why would damage to the right primary motor cortex cause contra-lesional (left sided) weakness?
due to the cross over of upper motor neurons at the medulla
are the motor neurons damaged in the primary motor cortex upper motor neurons or lower motor neurons?
UMN
waht is the supplemental motor area responsible for?
planning of movement, selection of appropriate motor plans and sequences, and coordination of the two sides of the body for complex movements
what is the frontal eye fields responsible for?
control of visual attention and voluntary eye movements
what is broca’s area?
found only on left side of frontal lobe (typically)
small region in the left hemisphere; key role in speech PRODUCTION
what is broca’s aphasia?
non-fluent aphasia; diminished speech output caused by damage to broca’s area (left frontal lobe)
- they understand, they also know what they want to say they just can’t
- sometimes they can write, sometimes not
- it is NOT a memory problem –> production problem
they sometimes can say words they have access to like yes/no - they commonly work with speech pathologists
frontal lobe: key cognitive areas
- dorsal lateral prefrontal cortex (DLPFC)
- orbital frontal cortex (OFC)
- medial prefrontal cortex (mPFC)
what is dorsolateral prefrontal cortex (DLPFC) responsible for?
executive functions and motor planning
what are executive functions
attentional control, short term working memory, self control & moderation of social behavior, decision making, judgement, planning, reasoning, problem solving… what else?
what is orbital frontal cortex (OFC) responsible for?
sensory integration, learning, prediction and decision making for emotional and reward-related behaviors
waht is the medial prefrontal cortex (mPFC) responsible for?
- impulse control
- motivation
- emotional component of decision making
- sociability
- memory
functions of parietal lobe
- terminal location for sensations coming in from the somatosensory system (skin, muscles, joints, etc)
- integrates somatosensory sensation with information from the special senses (vestibular) to form an overall perception
- higher order sensory experinces like music appreciation
what are the key regions of the parietal lobe
- primary somatosensory cortex (S1)
- posterior parietal cortex (PPC)
what is the primary somatosensory cortex (S1) responsible for?
also called post central gyrus!!!
- receives and processes touch, temp, pain, and conscious proprioceptive info from the body
what is the posterior parietal cortex (PPC) responsible for?
- motor planning
- visuospatial perception
- spatial attention
- integration of somatosensory
- visual
- auditory INPUT
What ‘ order’ of sensory neurons are found in the primary somatosensory cortex?
3rd order
apraxia?
difficulty with motorpalnning and coordination leading to loss of ability to execute skilled movement. despite physical ability to perform movement
- injury to frontal lobe (premotor cortex, DLPFC) and parietal lobes (PPC)
what is neglect? also called hemispacial neglect or hemi neglect
half the world is not perceived
- reduced awareness of stimuli on one side of the body. often damage to R parietal lobe
(no sensory loss strictly perception loss)
typically
- unaware of 1/2 their body
- typically manifests on left side of body (R parietal lobe)
- r parietal stroke –> there is an ability to overcome
why is neglect more common w/ R side lesions?
there are two visual lines come from the right side of the brain - this includes the only line to the left side of the body. (left side vision goes to right side)
temporal lobe functions
- aduitory processing (especially language and the identification of objects)
- memory/learning through connections with limbic system
what is the limbic system
emotional nervous system
temporal lobe: key areas
- auditory cortex (A1)
- olfactory cortex
- medial temporal lobe
- wernickes area
what is the auditory cortex (A1)
located in temporal lobe, awareness and processing of auditory stimuli
what is olfactory cortex
located in temporal lobe - awareness and prcessing of smell
what is the medial temporal lobe responsible for?
memory and learning
wernicke’s area
located on the temporal lobe (a little on parietal)
comprehension of written and spoken language
what is wernickes aphasia
fluent aphasia; diminished language comprehension
- LEFT temporal lobe only
how is this different from broccas aphasia?
functions of occipital lobe
- visual perception –> color, form, depth perception, distance, object/face recognition, visual info sharing and motion
- functions also rely heavily on other brain regions
occipital lobe: dorsal visual stream
WHERE an object is
occipital lobe: ventral visual stream
WHAT an object is
occipital lobe: key areas
- primary visual cortex (V1)
- secondary visual cortex (V2, V3, V3a, V4, V5)
primary visual cortex (V1)
process and sort incoming visual info and pass correct info to the morespecialized areas of the cortex
secondary visual cortex (V2, V3, V3a, V4, V5)
more specialized areas- process motion, color, etc.
pass on to dorsal or ventral stream
waht deficit would you expect with damage to the left primary visual cortex (V1)
deficit will be contralateral so loss to R visual field from both eyes
* lesion at occipital visual cortex: contralateral homonymous hemianopia, with macualr sparing
meaning of
homonymous hemianopia
same -homo
name/designation - nymous
half vision loss - half vision loss
what is the insular cortex
where is it located
- found deep in the lateral sulcus, in between the temporal and parietal lobes
- associated w/ eating and digestive functions, autonomicfunction and feelings related to a sensory experience such as pain or pleasure
what is the cingulate cortex
where is location
- found superior to the corpus callosum
- associated w/ basicdrive and motivations such as hunger, emotions and initation
look over the new homonculus
integrated motor learning
declarative/explecit memory
integrated motor learning
non declarative/implicit memory
–> procedualr (skills, habits) –>
striatum, cerebellum, motor cortex
go look up and label brain scans
what arethe 3 cerebral arteries
anteiror cerebral artery (ACA)
middle cerebral artery (MCA)
posterior cerrebral artery (PCA)
what does the ACA supply?
where does it course through?
supplies sensory and motor areas of the lower extremity
- course around the genu of the corpus callosum
genu = bend/knee so courses around the anterior bend of the corpus callosum
what does MCA supply?
supplies sensory and motor areas of the UE/face
What does PCA supply?
supplies functional territories including the visual cortex adn teh hippocampal formation
what do the MCA’s supply on the left hemisphere?
supplies the speech centers - brocca’s and wernikes
homunculus - what does the anterior cerebral artery supply?
motor (precentral gyrus) - trunk, leg, foot, genitals
sensory (postcentral gyrus) - trunk, leg, foot, genitals
homunculus - what does the middle cerebral artery supply?
motor (precentral gyrus) - arm, hand, face, tongue
sensory (postcentral gyrus) - arm, hand, face, tongue
posterior cerebral artery - homunculus
occipital lobe and a little bit of temporal lobe
cerebral vascualr injury - ischemic stroke
what is it?
why can it occur?
- interruption of arterial supply to an area results in decreased delivery of oxygenated blood to the tissue
- can occur bc of an acute blockage such as from an embolus or the gradual narrowing of the arteiral lumen ( stenosis), as in atherosclerosis
diseased carotid artery –> blood clot breaks off and travels –> blood clot lodges in cerebral artery, causing as troke
what is infarct
a localized area of ischemic neurosis resulting from sudden adn complete occlusion of arterial blood supply
What is a TIA?
transient ischemic attack –> mini stroke
cerebral vascular injury - hemorrhagic stroke
- occurs when an artery ruptures, releasing blood into the surrouding tissue; produces diffuse and extensive damage to brain
- commonly caused by ruptured aneurysm
- aneurysm in cerebral artery breaks open causing bleeding around the brain –> pressure of blood on brain cuases brain tissue death
acute vs. chronic: signs and symptoms evolve as you transition fro macute to chronic phases of a stroke
hyper acute infarct (0-6hrs)
- blood clot, MMP-9, early BBB disruption
- cytotoxic edema
tumor
a cancerous or noncancerous mass or growth of abnormal cells in the brain
- tumors can start in the brain, or cancer elsewehre in the body can spread to the brain
what does contralesional mean?
there is a lesion on the contralateral side
example: the patient had a R MCA stroke resulting in contralesional UE paresis
go pull up a brain scan
answer the following questions:
- was it an icshemic or hemorrhagic stroke
- which vessel was impacted? R or L?
- what does that vessel supply?
- what is found in the area that vessel supplies? L vs R
- what would you expect in terms of clinical presentaiton
- would the R/L or both sides of the body be affected?
- what time of imaging are you looking at
go do it! you got this!
