Anatomical Basis of EEG Flashcards
What are the electrical fields recorded during an EEG?
These are a (higher/lower) voltage than an AP, but they have a longer …. and cover a ….. area of neuronal membrane. Unlike an AP, these are … and not propagative.
Post-synaptic potentials
lower
duration
larger
static
The presence of an AP will create what two things?
- sink (area ions flow toward) - greater negative charge
- source (area ions flow from) - greater positive charge
An excitatoty synapse increased the relative (positive/negative) charge outside of the neuron. In this way, the synapse becomes a … while neuronal membrane becomes a …
negative
sink
source
An inhibitory synapse creates a relative (positive/negative) charge outside of the neuron. In this way the synapse becomes a … while the surrounding area is a ….
positive
source
sink
How is a dipole formed?
source to sink flow on the surface is mirrored in the reverse direction on the internal side, creating a ‘circular’ voltage flow
In order for dipoles to appear on the EEG, they must be…
simultaneous (additive)
occur in same polarity and close proximity to one another
dipole fields with mixed polarities are…
closed fields
large numbers of neurons densely packed together with nearly identical orientation will create …
open fields
What kind of field is required to create an EEG wave?
Open Field
What are the dendrites around the perikaryon called?
basal dendrites
Apical dendrites extend which way from the perikaryon?
superficially
a fiber projecting from the cerebral cortex to a neuron located “below” the cortex is called..
corticofugal fibers
Pyramidal neurons form the …. of the cerebral cortex and the majority of …
“output” - descending
interconnections within the cerebral cortex
Axons of pyramidal neurons form a major component of the …
Internal capsule
Pyramidal neurons forming Upper Motor Neurons are aka…
Giant Cells of Betz
What part of the pyramidal neurons is conducive for forming a strong dipole? Because of this, the pyramidal neurons form a …
distance between apical and basal dendrites
natural open dipole field
The cerebral cortex is organized into functional units called…
All the neurons in this seem to be activated at roughly the same time, leading to …
cortical columns
inhibition of surrounding cortical columns
What links the cortical columns together?
pyramidal axons
Lamina 1 of the cerebral cortex
- low density of cells
- synaptic center
- most input from matrix (M) cells of the thalamus
Lamina 2 and 3 of the cerebral cortex have…
pyramidal neurons projecting as association and commissural fibers
Lamina 4 of the cerebral cortex is the primary…
input center, some commissural fibers, but most arise from the core (C) cells of the thalamus
Lamina 5 of the cerebral cortex has the… pyramidal neurons and is the major…
largest
output layer for corticofugal fibers
What lamina layer forms most of the UMNs in the CNS?
Lamina 5
Lamina 6 of the cerebral cortex has pyramidal neurons projecting to…
thalamus and internal capsule
Lines of Gennari/Bands of Baillarger are in what lamina layers? What are they?
in Lamina IV and V
bands so prominent you can see with the naked eye
All individual voltage spikes recorded during a PSP from all the pyramidal neurons within a single cortical column create…
Local Field Potentials
When all local field potentials are recorded from the entire cerebral cortex, the trace is dubbed…
an EEG - electroencephalogram
What kind of EEG waves will appear when large scale neuronal interaction for motor or cognitive tasks is taking place?
gamma waves
from the anterior half of the brain, we will see what kind of wave form with motor function and concentrated thinking?
beta waves
What kind of waves are recorded from the posterior half of the brain while ‘at rest’?
alpha waves
What kind of waves are found in transition to and from sleep, and is characteristic of young children?
theta waves
What waves are often seen in infants and are characteristic of adult sleep?
delta waves
Rhythmicity indicates that most of the neurons in the sampling pool are responding in a …
This can be generated locally or can be driven by deeper cerebral structures. The primary source for rhythmicity is…
coordinated fashion
thalamus
Association fibers are axons linking a cortical column to another cortical column within the same hemisphere. They make up a portion of the…
corona radiata
What association fiber tract links the frontal and occipital lobes? It is the largest and longest group of association fibers.
Superior Longitudinal Fasciculus
Most association fibers are located in what two laminar layers?
Lamina I and III
What group of association fibers link the occipital and temporal lobes?
Inferior Longitudinal Fasciculus
What fibers are axons that link a cortical column in one cerebral hemisphere with a cortical column in another cerebral hemisphere?
commissural fibers
Commissural fibers form the …, a thick band of axons located deep to the…
corpus callosum
medial longitudinal fissure
The rostral portion of the corpus callosum is referred to as the … and is located superior to the … near the posterior end of the….
genu
optic chiasma
olfactory tract
The caudal portion of the corpus callosum is the … and is located superior to the …
splenium
tectum of the MB
The commissural fibers in certain areas of the corpus callosum are spatially organized as what?
genu - prefrontal
rostral body - premotor, supplementary motor
middle body - primary motor, somatic sensory
caudal body - posterior parietal
splenium - temporal and occipital
The inferior surface of the corpus callosum supports a vertical drape of tissue, the …
septum pellucidum
In addition to association and commissural fibers, the corona radiata is formed by axons from the …
internal capsule
What are the three main groups of axons within the internal capsule?
- thalamo-cortical tract
- cortico-thalamic tract
- corticofugal fibers (which synapse on non-thalamic centers)
What is the anterior limb of the internal capsule bordered by?
medial by caudate, lateral by putamen and globus pallidus
What tracts are within the anterior crus of the internal capsule?
corticopontine tract (from frontal lobe)
corticofugal fibers
anterior thalamic radiation (reciprocal connection b/t thalamic nuclei and neurons in the frontal lobe of the cortex)
What are the borders of the genu of the internal capsule?
What tract is in the genu?
medially by 3v, and lateraly by putamen
corticonuclear (corticobulbar) tract and thalamic radiation (thalamic nuclei to precentral gyrus)
What is the main path through the internal capsule for motor information?
through genu
What borders the posterior crus of the internal capsule?
medially is thalamus, laterally is putamen and globus pallidus
What tracts are within the posterior crus of the internal capsule?
corticopontine (from non-frontal) , corticospinal tract, corticorubral tract, superior thalamic radiation
What is the reciprocal connection between thalamic nuclei and neurons in the parietal lobe of teh cerebral cortex?
Superior Thalamic radiation
Conduit for most somatosensory information throught the internal capsule is from…
Superior Thalamic radiation
What tract courses inferior to the posterior crus of the internal capsule as part of the thalamic radiation? When it reaches the lateral surface of the globus pallidus, its name changes to what and goes where?
Where did this originate?
Sublenticular tract
Auditory radiation going to auditory cortex
Medial geniculate nucleus
The lateral geniculate nucleus gives rise to…. which courses posterior to the posterior crus, then projects caudally to the occipital lobe as the…
Retrolenticular tract
optic radiation
The lateral surface of the thalamus is covered by the…
external medullary layer
What is the vertical, Y shaped sheet of white matter, dividing the thalamus into anterior, medial and lateral groups called?
Internal medullary lamina
Where does the anterior thalamic nucleus project to and what does it transmit?
to cingulate and hypothalamus
transmits emotion and memory
Where does the dorsomedial nuc of thalamus project to and what does it transmit?
projects to prefrontal and hypothalamus
transmits sensory info for mood and motor planning
Where does the dorsolateral nuc of thalamus project to and what does it tranmit?
to association areas
transmitting multisensory info
Where does the ventral anterior nuc of thalamus project to and what does it transmit?
to premotor
transmits motor activity
Where does the ventral lateral nuc of thalamus project to and what does it transmit?
to primary motor and pre motor
transmits motor activity, motor planning
What does the VPL nuc project to and transmit?
to primary sensory
transmits pain, touch, body temp
What does the VPM nuc project to and transmit?
to primary sensory
transmits pain, touch, temp, taste (head and face)
Where does the medial geniculate project to and what does it transmit?
to primary auditory
transmits audition
Where does the lateral geniculate project to and what does it transmit?
primary visual
transmits vision
What does the intralaminar nuc of thalamus project to and what does it transmit?
thalamic nuclei
transmits arousal, pain
Thalamus is a relay center to the cortex, but it also has numerous… that form feedback and feed forward controls
inhibitory interneurons
What of the thalamus serves as a master regulatory center for the activity level of the thalamus as a whole?
Laminar nuclei
Laminar nuclei are a major synaptic target of a diffuse body of neurons collectively termed…
Reticular formation
