NROb60 - Final Exam
Study Guide
lecture 6 - The first phase of human brain-imaging involved X-ray based methods, such
as----- - Answer pneumoencephalography
pneumoencephalography - how does this work generally , what are the cons of this
method - Answer •Air is injected into subarachnoid space to improve X-ray contrast
•Makes the ventricles more translucent than surrounding tissue - specifically the lateral
ventricles
- You can see the c shape of the lateral ventricles
- Was useful for visualizing ventricular anomalies causing hydrocephalus, but comes
with risks and discomfort.
Very invasive and unpelasent
But you cant see the brain completely
how does cerebral angiography generally work - Answer , X-ray images reveal blood
vessels if a contrast agent is introduced into arterial circulation
•X-ray images taken in different planes to visualize full network
•Time-lapse images will spread through major arteries first
- helps Visualize different arteries
- Done in a timeline sequence so you can watch the contrast dye go into all the little
branches
The approach allowed identification of arterio-venous malformations and other vascular
anomalies, such as arterial occlusions • Helped inform clinical assessments of strokes
however there are substantial risks with this
in slide 7 week 7 how do you which artery is being supplied - Answer Internal carotid
artery aca and mca are being supplied - theres a lack of dye in the back of the brain and
cerebellum so that's how we know
Here visualzing arteries
,computerized tomography (CT) - Answer the X-ray source and
detector are moved around the individual's head
•Distinguishes gray and white matter, ventricles, and major anatomical structures
•Spatial resolution of a few millimeters
In CT, a narrow X-ray beam and very sensitive detectors are placed on opposite sides of
the head probe a small portion of tissue at a time with limited radiation exposure
- The X-ray tube and detectors rotate around the head, collecting radiodensity
information from every orientation around a narrow slice, that can be processed to
produce a tomographic image. The individual is then moved very slowly through the
scanner to complete a set of serial sections
CT scans readily distinguish gray and white matter, differentiates the ventricles, and
major anatomical structures (spatial resolution of several millimeters) • The white matter
tracts appear as the darker color
what image does a ct scan create and what is this useful to study - Answer Created a
horizontal image in this case - we can see that white matter is darker color, grey matter
is lighter and the ventricles are black here
Useful for detecting brain lesions like tumors, or hematoma you can visualize easily
CT is useful in detecting brain lesions where the damage has a different tissue density
than the normal brain tissue
•Metastatic brain tumors in breast cancer patient -->White spots throughout gray and
white matter
what are some cons of ct - Answer risks associated with unnecessary radiation
exposure and due to its relatively low resolution of brain structures (compared to MRI
Development of -------- made it possible to construct detailed spatial images - Answer
Magnetic Resonance Imaging (MRI)
explain the functions of mri and how it works - Answer •Safe, noninvasive and versatile
Based on the physics of atomic motion
A magnetic coil is placed around the head to activate and record magnetic resonance
signal
The nuclei of some atoms act as spinning magnets, randomly positioned normally in the
body
• When placed in a strong magnitude field of the MRI machine, these atoms will line up
with the field and spin at a frequency that is dependent on the field strength
,• A brief radiofrequency pulse knocks the atoms out of alignment with the field and when
turned off, the protons relax and emit a radio signal
• Almost all MRI scanners use detectors turned to the radio frequencies of spinning
hydrogen nuclei in water molecules, creating images based on the distribution of water
in different tissues.
essentially Putting a person in a very strong magnet, atoms within soft tissue oreitn
randomly in normal cirucmtsances , but rn the mri is trelying on water
When placed under the strong magnetic force it forces the molecules to orient in the
same direction
Radio pulse makes it briefly disoroiet and then when it relaxes it orients it properly
Different tissue has diff water content so you can see different things
Now resolution is a mm
what resolution does mri have , what does the light or dark depend on - Answer
•Millimeter resolution
•Light vs dark can reverse depending on pulse sequence used - soft tissue contrast can
be manipulated by adjusting the time at which the realigning hydrogen signal is
measured
---- is a variant of MRI and identifies major axon pathways in the brain - Answer Diffusion
Tensor Imaging (DTI)
what does dti do - Answer •Detects similarities in the direction of water molecules within
specific regions of the magnetic field.
•Can't resolve individual axons, but can visualize the origin,
orientation, course, and termination of axonal bundles
how does the dti work - Answer Used for when hydrogen atoms are moving and
orienting to magnetic and being disrupted by the energy pulse
Energy relates to types of tissue there is - when there are major axonal tracts in the
brain they share more similairites than tissues in the brain - can represent major fiber
tracts - looking at tracts going in the same direction
Identifies major axon pathways in the brain by detecting similarities in the direction of
water molecules within specific regions of the magnetic field, to visualize axonal
connections between regions.
• This information is then assembled into an image that indicates the degree of
alignment of water molecules in the tissue.
, • Maximally aligned molecules (shown in different colors, depending upon shared
directions) define regions where major axon tracts are found in the cortical white matter
and other brain regions.
• Doesn't have the resolution to portray individual axons, but the origin, orientation,
course, and termination of axonal bundles can be effectively visualized
How do we map the major input and output connections to a brain region? - Answer -
using tract tracing
Multiple different inputs come into a single brain region, and neurons from one region
can project to many others
Looking more at tract tracing and cell identity
Don't worry about the acronyms and things
First conceptual idea -
We need to understand what parts of the brain are connected to each other to
understand how they work - we look at this using tract tracing
How do we map the connections of specific subpopulations of neurons based on their
identity? - Answer Within a single brain region, there is many different types of neurons
that have unique functions --> so you might have projection neurons - main cell types
that project out and send information elsewhere but also interneuonrs (these are local
their dendrites and axons are all within the certain brain region, they don't project out
they stay local and tend to be inhibitory)
Even within projection neurons you could have different types of projection neurons
projection neurons vs interneurons - Answer projection neurons --> those that project
out of nucleus A and travel to nucleus B)
local interneurons --> dendrites and terminals stay within nucleus A, functioning to
modulate information processing within nucleus A
The use of ---as a tracing technique revolutionized
neuroanatomical tract tracing throughout the ---- - Answer HRP = horse radish
peroxidase , 1970's
how does HRP work - Answer Injected it in area a - profused the animal, sliced the brain
and saw that it didn't label cells in area a but in area b it stained all the cell bodies there
that we now know projected to area a
When you injected in area a it was taken up and into axon terminals and travelled
backwords to get into the cell body
Now we can follow different sources of input
Study Guide
lecture 6 - The first phase of human brain-imaging involved X-ray based methods, such
as----- - Answer pneumoencephalography
pneumoencephalography - how does this work generally , what are the cons of this
method - Answer •Air is injected into subarachnoid space to improve X-ray contrast
•Makes the ventricles more translucent than surrounding tissue - specifically the lateral
ventricles
- You can see the c shape of the lateral ventricles
- Was useful for visualizing ventricular anomalies causing hydrocephalus, but comes
with risks and discomfort.
Very invasive and unpelasent
But you cant see the brain completely
how does cerebral angiography generally work - Answer , X-ray images reveal blood
vessels if a contrast agent is introduced into arterial circulation
•X-ray images taken in different planes to visualize full network
•Time-lapse images will spread through major arteries first
- helps Visualize different arteries
- Done in a timeline sequence so you can watch the contrast dye go into all the little
branches
The approach allowed identification of arterio-venous malformations and other vascular
anomalies, such as arterial occlusions • Helped inform clinical assessments of strokes
however there are substantial risks with this
in slide 7 week 7 how do you which artery is being supplied - Answer Internal carotid
artery aca and mca are being supplied - theres a lack of dye in the back of the brain and
cerebellum so that's how we know
Here visualzing arteries
,computerized tomography (CT) - Answer the X-ray source and
detector are moved around the individual's head
•Distinguishes gray and white matter, ventricles, and major anatomical structures
•Spatial resolution of a few millimeters
In CT, a narrow X-ray beam and very sensitive detectors are placed on opposite sides of
the head probe a small portion of tissue at a time with limited radiation exposure
- The X-ray tube and detectors rotate around the head, collecting radiodensity
information from every orientation around a narrow slice, that can be processed to
produce a tomographic image. The individual is then moved very slowly through the
scanner to complete a set of serial sections
CT scans readily distinguish gray and white matter, differentiates the ventricles, and
major anatomical structures (spatial resolution of several millimeters) • The white matter
tracts appear as the darker color
what image does a ct scan create and what is this useful to study - Answer Created a
horizontal image in this case - we can see that white matter is darker color, grey matter
is lighter and the ventricles are black here
Useful for detecting brain lesions like tumors, or hematoma you can visualize easily
CT is useful in detecting brain lesions where the damage has a different tissue density
than the normal brain tissue
•Metastatic brain tumors in breast cancer patient -->White spots throughout gray and
white matter
what are some cons of ct - Answer risks associated with unnecessary radiation
exposure and due to its relatively low resolution of brain structures (compared to MRI
Development of -------- made it possible to construct detailed spatial images - Answer
Magnetic Resonance Imaging (MRI)
explain the functions of mri and how it works - Answer •Safe, noninvasive and versatile
Based on the physics of atomic motion
A magnetic coil is placed around the head to activate and record magnetic resonance
signal
The nuclei of some atoms act as spinning magnets, randomly positioned normally in the
body
• When placed in a strong magnitude field of the MRI machine, these atoms will line up
with the field and spin at a frequency that is dependent on the field strength
,• A brief radiofrequency pulse knocks the atoms out of alignment with the field and when
turned off, the protons relax and emit a radio signal
• Almost all MRI scanners use detectors turned to the radio frequencies of spinning
hydrogen nuclei in water molecules, creating images based on the distribution of water
in different tissues.
essentially Putting a person in a very strong magnet, atoms within soft tissue oreitn
randomly in normal cirucmtsances , but rn the mri is trelying on water
When placed under the strong magnetic force it forces the molecules to orient in the
same direction
Radio pulse makes it briefly disoroiet and then when it relaxes it orients it properly
Different tissue has diff water content so you can see different things
Now resolution is a mm
what resolution does mri have , what does the light or dark depend on - Answer
•Millimeter resolution
•Light vs dark can reverse depending on pulse sequence used - soft tissue contrast can
be manipulated by adjusting the time at which the realigning hydrogen signal is
measured
---- is a variant of MRI and identifies major axon pathways in the brain - Answer Diffusion
Tensor Imaging (DTI)
what does dti do - Answer •Detects similarities in the direction of water molecules within
specific regions of the magnetic field.
•Can't resolve individual axons, but can visualize the origin,
orientation, course, and termination of axonal bundles
how does the dti work - Answer Used for when hydrogen atoms are moving and
orienting to magnetic and being disrupted by the energy pulse
Energy relates to types of tissue there is - when there are major axonal tracts in the
brain they share more similairites than tissues in the brain - can represent major fiber
tracts - looking at tracts going in the same direction
Identifies major axon pathways in the brain by detecting similarities in the direction of
water molecules within specific regions of the magnetic field, to visualize axonal
connections between regions.
• This information is then assembled into an image that indicates the degree of
alignment of water molecules in the tissue.
, • Maximally aligned molecules (shown in different colors, depending upon shared
directions) define regions where major axon tracts are found in the cortical white matter
and other brain regions.
• Doesn't have the resolution to portray individual axons, but the origin, orientation,
course, and termination of axonal bundles can be effectively visualized
How do we map the major input and output connections to a brain region? - Answer -
using tract tracing
Multiple different inputs come into a single brain region, and neurons from one region
can project to many others
Looking more at tract tracing and cell identity
Don't worry about the acronyms and things
First conceptual idea -
We need to understand what parts of the brain are connected to each other to
understand how they work - we look at this using tract tracing
How do we map the connections of specific subpopulations of neurons based on their
identity? - Answer Within a single brain region, there is many different types of neurons
that have unique functions --> so you might have projection neurons - main cell types
that project out and send information elsewhere but also interneuonrs (these are local
their dendrites and axons are all within the certain brain region, they don't project out
they stay local and tend to be inhibitory)
Even within projection neurons you could have different types of projection neurons
projection neurons vs interneurons - Answer projection neurons --> those that project
out of nucleus A and travel to nucleus B)
local interneurons --> dendrites and terminals stay within nucleus A, functioning to
modulate information processing within nucleus A
The use of ---as a tracing technique revolutionized
neuroanatomical tract tracing throughout the ---- - Answer HRP = horse radish
peroxidase , 1970's
how does HRP work - Answer Injected it in area a - profused the animal, sliced the brain
and saw that it didn't label cells in area a but in area b it stained all the cell bodies there
that we now know projected to area a
When you injected in area a it was taken up and into axon terminals and travelled
backwords to get into the cell body
Now we can follow different sources of input
