Lecture 3: forebrain - telencephalon & diencephalon Flashcards
what two structures divide the forebrain and midbrain?
mammillary body and posterior commissure
Amygdala and hippocampus are components of _____ system and located in the ______
limbic
telencephalon
cerebral cortex is ______ thick and is responsible for _______ functions like perception, memory and decision making
2-4 mm
cognitive
what are the two regions of the cerebral cortex & how do they differ?
- neocortex - newer, 6 organized layers, higher level thinking
- allocortex - part of limbic system, less than
6 layers, made up of two regions
what are the two regions of the allocortex?
- paleocortex - 3-5 layers, found in amygdala, olfactory cortex (smell)
- archicortex - found in hippocampus, only 3 layers, memory
list the 6 layers of the neocortex from outermost –> innermost
- molecular layer: almost no neurons
- external granular layer
- external pyramidal layer
- internal granular layer
- internal pyramidal layer
- multiform layer
sensory or motor cortex?
thicker, agranular =
thinner, granular =
motor
sensory
which cerebral arteries support the frontal lobe?
MCA
ACA
what are two types of neurons in the neocortex and how do they differ?
what are their neurotransmitters?
- pyramidal cells - sends signal out of cerebral cortex (efferent) with long range projections (dendrites) that ascend to layer I. pyramidal shaped cell bodies. excitatory neurons = glutamate/aspartate as neurotransmitter
- interneurons - processes afferent info (stays in cerebral cortex). smaller, more localized dendrites. mainly inhibitory neurons = GABA as neurotransmitter but also excitatory neurons = glutamate as neurotransmitter
Name the correct Brodmann’s area:
- M1:
- S1:
- V1:
- A1:
- Broca’s area (& which hemisphere?)
- Wernicke’s area (& which hemisphere?)
- 4 (precentral gyrus, frontal lobe)
- 3, 1, 2 (postcentral gyrus, parietal lobe)
- 17 (occipital lobe)
- 41, 42 (temporal lobe)
- 44, 45 ; L hemisphere
- 22 ; L hemisphere
regarding Broca’s and Wernicke’s area, which side corresponding areas are for language prosody?
Right
what is the difference between unimodal association cortex and multimodal association cortex?
unimodal - input mainly from S1, location of memory to associated primary cortex
multimodal - input from different sources, bidirectional communication w/ sensory & motor cortex, metacognition & integration
** MRI slide 12 **
what is the basic functional unit of the neocortex w/ 100 neurons?
minicolumn
______ interneurons = localized
_______ interneurons = long distance
cortical
subcortical
_______ is an example of vertical communication within axonal bundles because the communication goes _____ to _______
______ is an example of transverse communication within axonal bundles because the communication goes ______ to _______
corticospinal tract ; top to bottom & vice versa
corpus callosum ; side to side
outer band of Baillarger comes from ________ and is in layer _____
inner band of Baillarger goes to ______ and is in layer _____
thalamus ; layer IV
other CNS locations ; layer V
which layer in the neocortex is NOT an efferent fiber?
layer IV - afferent
neocortex layers I-III contain ______ and ______ fibers
how do they communicate?
association fibers - communicating in the same hemisphere
commissural fibers - communicating between 2 hemispheres
neocortex layers IV-VI contain _______ fibers
how do they communicate?
projection fibers
layer IV - from thalamus to cortex
layer V & VI - from cortex to other subcortical CNS structures
long association fibers:
- superior longitudinal fasciculus connects:
- arcuate fasciculus connects:
- uncinate fasciculus connects:
- cingulum connects:
- frontal, parietal and occipital lobes
- frontal and temporal lobes
- orbitofrontal and temporal lobe
- cingulate gyrus and parahippocampal gyrus
what are the 3 commissural fiber tracts?
what do they connect?
- corpus callosum - forms roof of both lateral ventricles
- anterior commissure - connects part of bilateral olfactory pathways and temporal lobes
- posterior commissure - connects part of bilateral visual pathways for pupillary reflex
what are projection fibers?
axonal bundles that connect cerebral cortex and subcortical CNS structures
what are the 3 parts to the projection fibers?
- what are the pathways/tracts that correspond with each of the functions?
- sensory pathways - afferent fibers mostly relayed by thalamus except olfactory pathway
- coordination and planning - corticobasal nuclei tract and corticopontine tract (most of efferent fibers)
- motor control - corticobulbar tract (efferent fibers to brainstem) and corticospinal tract (efferent fibers to spinal cord)
projection fibers form tracts that pass between _______ and _______
basal nuclei and thalamus
what is the genu?
between the anterior and posterior limb - interventricular foramen is also located here
what are the 4 basal nuclei components in the telencephalon?
putamen
nucleus accumbens
caudate
globus pallidus
what are gaps between caudate and putamen/globus pallidus known as?
anterior limb of internal capsule
what are the 4 primary components and the one cranial nerve that make up the diencephalon?
** which one is a component of the basal nuclei?
epithalamus (pineal gland)
thalamus
hypothalamus
subthalamus (subthalamic nuclei)**
optic nerve, CN II
another name for the posterior lobe of the pituitary gland and located in the hypothalamus
neurohypophysis
what does the intramedullary lamina do?
divides the anterior, medial and lateral compartments of the thalamus
–> which further divide into different nuclei according to their functions
slide 24 CT scan
what are the functions of the following thalamic nuclei?
- anterior nucleus
- ventral anterior/lateral nuclei (VA/VL)
- ventral posterolateral nucleus (VPL)
- ventral posteromedial nucleus (VPM)
- lateral geniculate nucleus (LG)
- medial geniculate nucleus (MG)
- limbic system (memory, emotions, behavior regulation)
- motor control
- somatic sensory of body
- somatic sensory of face/head
- visual pathway (Light)
- auditory pathway (Music)
center of ANS
bridging nervous system and endocrine system
defines life and death
regulates homeostasis
hypothalamus
the frontal lobe is part of the primary motor cortex which is located where? functions?
precentral gyrus, M1
head and body motor functions with input from basal nuclei and cerebellum
what does the premotor cortex in the frontal lobe do? it has strong input to and from the _______
organizes and plans postural adjustments for skilled movement
basal nuclei
what does the supplementary motor area in the frontal lobe do?
motor planing - praxis (organizing, sequencing)
is there is L sided injury to the supplementary motor area, what would the pt experience?
apraxia
no purposeful/ordered movements which peripheral structures function normally
what does the Broca’s area do and where is it located?
coordinating speech muscles
in motor association cortex
what does the frontal eye field area in the frontal lobe do?
coordinate eye movement for balance - CN III/VI
drives eyes to contralateral side
a _______ injury to the frontal eye field causes a gain of function, moves eyes to the normal side. Example is epilepsy or infection
irritative
a ______ injury to the frontal eye field causes a loss of function, moves eyes to injured side. Example is a stroke
destructive
what is the last maturing brain structure?
left dorsolateral prefrontal cortex
what is the function of the orbitofrontal cortex?
personality, limbic system
Where are the most efferent fibers located?
Internal capsule
the parietal lobe is part of the ______ cortex located on the ______ and has a ___ neuron pathway
primary somatic sensory cortex
postcentral gyrus
3
a defect in the primary somatic sensory cortex can cause agnosia. what is that?
lack of knowledge, probably with intact other sensory perception
–> inability to interpret sensations
the right hemisphere in the parietal lobe does what?
attention
giving emotional significance to events and language
music perception
complex visual-spatial skills –> spatial cognition
if you have loss of function of R hemisphere in parietal lobe, what is a result?
left hemineglect syndrome (left side neglect)
the left hemisphere in the parietal lobe does what?
praxis (coordinating, planning, moving)
motor function
damage to the left hemisphere in the parietal lobe causes ___
apraxia (loss of ability to execute skilled movement despite having the physical ability to do so)
the corticospinal tract mainly functions in _______, which comes from the frontal lobe.
However, ______% of axons in the corticospinal tract come from the _________ lobe, which deals mainly with sensory
motor control
30%
parietal
which cortex is the occipital lobe located in?
_____ neuron pathway
has the _____-otopy, which is ?
primary visual cortex
3
retinotopy - mapping of visual input
what is the flow of the 3 neuron pathway for visual stimuli?
1st order neurons: retina –> transmit visual info from photoreceptors to brain to form optic nerve
2nd: optic nerve exchanges retina fibers at optic chiasm (relay station)
3rd: optic tract synapses in LGN where it sends visual info to V1 in occipital lobe to process
vision is a _______ perception.
there are many _______ ______ that project to multiple locations that work together to process visual stimuli for circadian rhythm and other functions
learned
parallel pathways
which cortex is the temporal lobe located in?
_____ neuron system
has the _____-otopy, which is ?
primary auditory cortex
4
tonotopy –> spatial arrangement of where sounds of different frequency are processed
what are functions of the primary auditory cortex?
initial area for language processing
decoding sounds to meaningful words
localization of sound resources
association area for language
slide 36 picture
L hemisphere is in charge of _____
R hemisphere is in charge of _______
language reception and expression
prosody of language (rhythm and sound)
Wernicke’s area is Brodman area _____
if there is damage to this area, what happens?
22
difficulty understanding language and forming meaningful sentences
Broca’s area is Brodman area ___ and ___
if there is damage to this area, what happens?
44 and 45
patient knows what they want to say but can’t pronounce words
integration of L and R hemisphere is through the ______ _______
corpus callosum
receptive/fluent aphasia is damage to the _____
–> alexia is:
wernicke’s area
unable to read
expressive/non-fluent aphasia is damage to the _______
–> agraphia is:
broca’s area
unable to write
what is conduction aphasia and what structure is impaired to cause this?
dissociation of comprehension and expression
arcuate fasciculus impaired
