Nervous System Structure Flashcards
Part of spinal cord carrying touch info (ipsilateral) to medulla, neurons in medulla cross and connects to thalamus on contralateral side
Dorsal columns
This midbrain neurons have wide projections throughout the NS
Tegmental neurons
Guidance cue secreted by cells in the MZ repels the axon and attracts the apical dendrite during differentiation
Semaphorin 3A
This is fully developed in humans at birth while this continues to grow during childhood
Medulla fully developed, cortex continues to grow
In between telencephalic vesicles
Diencephalon
Has no axons or dendrites, just the cell body
Neuroblast
Allowed for the first non-invasively revealed organization of gray and white matter in the brain and the position of the ventricles
Computed tomography - CT
Towards the outside, top of brain
Pial surface
Cut to divide top and bottom
Horizontal
Scan that excites protons in the human body to high energy state with EM waves and measures radio freqs emitted as they return to lower energy states
Magnetic resonance imaging - MRI
The most superficial layer of this has few neurons (layer I or molecular layer)
Cerebral cortex
Responsible for pupil dilation, stimulate glucose production and release in the liver
Autonomic/visceral nervous system
PET and fMRIs are these
Functional brain imaging
The process of the neural plate forming the neural tube
Neurulation
Name the 4 ventricles
2 lateral ventricles, the third ventricle, and the fourth ventricle
What absorbs the CSF?
Vasculature of the brain
The spider web like meninges layer in the middle
Arachnoid mater (membrane)
This forms the cerebral cortex and basal telencephalon in forebrain differentiation
Telencephalon
How are the factors that regulate gene expression differentially passed on to the daughter cell?
Depending on which plane the cell is cleaved
Towards the front of an animal (head)
Anterior/rostral
How are the lateral ventricles and third ventricle connected to the fourth ventricle?
Cerebral aqueduct
Voluntary, soma in CNS, axons in PNS
Somatic nervous system
Forebrain neurons extend axons in 3 major systems, what are they?
Cortical white matter, corpus callous, internal capsule
Exit the brain stem and gather info and send it to head, face, and neck
Cranial nerves
Bundle of axons in the PNS
Nerve
Ventricular zone precursor cells are made of these
Notch-1 and Numb
Thickness of this is about the same in humans, monkeys, mice, etc
Cortex
Plane that divides left and right
Sagittal
Daughter cells remain in VZ to divide again (neurogenesis)
Cleavage in ventricular plane
This has many more folds in humans
Cortex
Type of cortex medial to lateral ventricles, one cell layer, involved in learning and memory
Hippocampus
This part of the forebrain also communicates with the brain stem via the internal capsule. Also has some connections to the spinal cord
Cortex
Motor spinal nerves
Ventral roots
The 6 stages of nervous system development
- neurogenesis
- cell migration
- differentiation
- synaptogenesis
- neuronal cell death
- synapse rearrangement
About 1/3 of these migrate to the cortex horizontally while the others just go bottom to top in migration
Neuroblasts
MRI based neuroimaging technique that detects how water travels along the white matter tracts in the brain
Diffusion tensor imaging (DTI)
The three germ layers are formed after this
Gastrulation
This has expanded by adding new areas (secondary sensory areas), can be seen by comparing the cortex of various species such as cats, rats, and humans
Cortex
Towards the top/back of an animal
Dorsal
Migration of cells is driven by this
Region of generation
In the basal telencephalon of the forebrain, it is important in control of movement by the cortex
Basal ganglia
Some are part of the CNS others part of the PNS (somatic and visceral)
Cranial nerves
The fourth ventricle is surrounded by the pons, medulla, and cerebellum in both of these brains
Rat and human
What does the protein chords blocking action of BMP in neural plate lead to?
Nervous system development
Forebrain neurons extended to and from the cortex
Cortical white matter
Daughter cell has symmetric notch 1 and numb expression
Vertical cleavage
Towards the back of the brain (back of head)
Posterior/caudal
Contains more glia than neurons
Cerebrum
Caudal hindbrain becomes this
Medulla
These develop neurites which differentiate into neurons in differentiation
Neuroblasts
Has both sensory and motor (smooth muscle) functions. Axons innervate organs, glands, blood vessels
Autonomic/visceral nervous system
The most important part of the forebrain
Cerebral cortex
Daughter cell has differential protein expression, notch 1 cell will migrate away and numb cell with remain and continue to proliferate
Horizontal cleavage
Secretes CSF
Choroid plexus
Some molecules move in this by a more semi-selective mechanism
BBB
Some neuroectoderm becomes this which forms PNS cells, skull, and melanocytes
Neural crest
Same side
Ipsilateral
Cells leave VZ migrate past subplate form this
Corical plate
Can command contraction and relaxation of muscles that form the intestinal and vascular walls (smooth muscles)
Autonomic/visceral nervous system
Plane that divides front and back
Coronal
This is involved in sensory systems and movement
Midbrain
Involuntary
Autonomic/visceral nervous system
Hindbrain structure that involves crossing over
Pyramidal decussation (decussation = crossing over)
How do most individual brain regions change in size relative to brain size? Is this always the case?
They increase in proportion to brain size, some parts in some species expand to a greater extent
Has ipsilateral control (CNS)
Cerebellum
An improvement on the PET scan
Functional MRI (fMRI)
The difference in these two fluids lies in the protein levels only. Which one has the higher protein levels?
CSF and blood plasma. Blood plasma has higher protein levels
These migrate from VZ to the MZ in differentiation
Differentiated pyramidal neurons
Part of spinal cord receiving input from the dorsal root
Dorsal horn
Midbrain structure including the substantial nigra and red nucleus involved in movement as well as pain, pleasure, mood, and consciousness functions
Tegmentum
These scans are used to measure blood flow and metabolism
Functional brain imaging
Will become the hindbrain, connects to caudal neural tube, forms spinal cord
Rhombencephalon
Cells in capillaries that help in the creation of the BBB
Endothelial cells
These cells in the cerebral cortex extend to layer I (molecular layer)
Pyramidal cells
Part of spinal cord containing interneurons, coordinates sensory and brain info to form output
Intermediate
These are markers for the telencephalon in forebrain differentiation
Lateral ventricles
What size regions develop later?
Larger regions
Anatomical marker of the hindbrain
Fourth ventricle
Towards the midline
Medial
CNS neuronal cell bodies
Gray matter
The telencephalon is rostral to the diencephalon in these two brains
Rat and human
Forebrain neurons extended to form links between the cortex and thalamus
Internal capsule
What are the 3 germ layers
Endoderm, mesoderm, ectoderm
Drawbacks are taking several minutes to process and not great resolution
PET - positron emission tomography
Three types of cortex
- hippocampus
- olfactory cortex
- neocortex
Use radial processes to migrate form the VZ to the surface of the cortex in migration
Neuroblasts
Cut to divide front and back
Coronal
Posterior neural tube doesn’t close, can survive with this
Spina bifida
This is between the tectum and tegmentum and is a good landmark for the midbrain
Cerebral aqueduct
The neural plate is part of this which the nervous system arises from
Ectoderm
SLIDE 58
SLIDE 58
Hindbrain structure involved in other sensory (auditory, taste, touch) and motor functions (tongue)
Medulla
Takes several minutes to gather data, but a resolution of 5-10 mm^3 can be achieved
PET - positron emission tomography
Contains as many cells as cerebrum but has more neurons, controls movement, many connections to cerebrum and spinal cord, right side controls right side and vice versa (ipsilateral)
Cerebellum
How is the cortex assembled in migration?
Inside out. Each new layer is composed of cells that migrate past existing layers
Composed of somatic nervous system and autonomic/visceral nervous system
Peripheral nervous system (PNS)
Dorsal of the midbrain becomes this
Tectum
Towards the back of an animal (rear)
Posterior/caudal
Axons in the CNS
White matter
This is where the neurons in the spinal cord cross over to the opposite side of the brain in the hindbrain
Pyramidal decussation
Increased number of new neurons correlates with what in rats?
Better performance on hippocampus dependent memory tasks
The wall of the brain consists of these two layers
Ventricular zone and marginal zone
Control BP by regulating heart rate and diameter of blood vessels
Autonomic/visceral nervous system
How does cortical representation change between animals?
Different animals have different cortical representation for different things
This becomes that thalamus and hypothalamus in forebrain differentiation
Diencephalon
How far do the meninges extend?
The whole brain and length of the spinal cord
Carry sensory info to axons which bring info to the CNS
Afferent
What is the CNS surrounded by?
The meninges (3 membranes)
Allows for O2, CO2, small lipophilic molecules, drugs, and alcohol to diffuse out
BBB
The meninges layer up against the brain
Pia mater
What two things do precursor cells give rise to in neurogenesis?
other pre cursor cells or to differentiated cells
Walls of the neural groove (neural folds) fuse to form this on embryonic day 22
Neural tube
Information is relayed to the opposite side of the cerebellum from the 20 million descending axons that synapse here
Pons
Scan using 2-deoxyglucose (2-DG) labeled with a positron emitting isotope. 2-DG taken up by cells and more actives cells take up more. Amount taken up is detected and provides a metabolic picture
PET - positron emission tomography
Will become the midbrain
Mesencephalon
Why do different animals have varying brain structures?
To fit certain roles
Midbrain structure that relays info from ear to thalamus
Inferior colliculus
At 3 weeks of gestation, this forms in the neural plate
Neural groove
This becomes proportionally larger in primates
Cortex
This midbrain structure becomes the inferior colliculus and superior colliculus (optic tectum)
Tectum
General way a PET scan works
More active cells = more positrons = more photons = more light
Group of axons which run together, don’t have to start and end at the same place
Bundle
Towards the top of the brain (top of head)
Dorsal
12 pairs, numbered by Galen, anterior to posterior
Cranial nerves
SLIDE 7
SLIDE 7
What is the order of differentiation?
- Neurons
- Astrocytes
- Oligodendrocytes
Inhibitory interneurons and oligos generated here
Ventral regions of the VZ
Endothelial cell tight junctions prevent exit from capillary lumen
BBB
These are used to treat hydrocephalus
Shunts
The brain is derived from these which form at the rostral end of the neural tube
3 primary vesicles - Prosencephalon, mesencephalon, and rhombencephalon
Spinal cord axons from descending corticospinal tract which crossed at pyramidal decussation that innervate intermediate zone and ventral horn voluntary movement
Lateral column axons
Physical and mental activity increases what in rats?
Neurogenesis
This is derived from the walls of the neural tube
Complete CNS
90% (20 million) of descending axons passing through the midbrain synapse here
Pons
Divided into two sides with right receiving input from and controlling movement of left side and vice versa (contralateral)
Cerebrum
This is a marker for diencephalon in forebrain differentiation
Third ventricle
Towards the bottom/belly of an animal
Ventral
Flat disc with three tissue layers (germ layers)
Embryo
Group of axons which run together and have the same origin and destination
Tract
Sulci and gyri create a major expansion in surface area (1100 cm^2) in humans brains compared to these animals
Rats
These fuse with the diencephalon in forebrain differentiation
Ventromedial surfaces
Type of cortex that is two cell layers, posterior to olfactory bulb
Olfactory cortex
Group of neurons in a thin sheet (layers)
Cortex
This is directed by numerous signals released by cells which direct changes in gene expression another cells having receptors for these. Signals are often expressed in specific gradients at specific times
Development of the nervous system
The diencephalon surrounds the third ventricle in both of these brains
Rat and human
Away from the midline
Lateral
Arises from tufts of cells within the walls of the ventricle (it is located in the walls of the ventricles)
Choroid plexus
Has neuronal cell bodies in layers
Cerebral cortex
How do compounds need to be designed to treat the brain?
Have to cross the BBB like dopa to treat Parkinson’s bc DA cant cross
The midbrains surrounds the cerebral aqueduct in both of these brains
Rat and human
How is the fate of daughter cells in neurogenesis determined?
It depends on the plane of division
Brodmann’s area 4
Motor
He made a cytoarchitectural map for the areas of the neocortex that gave areas with common structure numbers
Brodmann
Hindbrain tract that is a pyramidal tract controlling fingers, toes, fine motor skills; it’s a motor tract
Corticospinal tract
Can cause birth defects, 1 out of 500 births, most due to folic acid deficiency
Failure of neural tube to close
This has association areas that have developed more recently in the primate brain
Cortex
Developed by Hounsfield and Cormack in 1979 with the goal to construct a 3D image of a brain slice
Computed tomography - CT
X rays penetrate through the body and are absorbed by radio opaque tissues which form a shadow that X ray sensitive film can detect and use to construct a 2D X ray image
Computed tomography - CT
All human brains have the same pattern of this and the differences are in this
Same pattern of structure but differences in connections
First cells in cortical plate form this
Layer IV
This becomes smaller in primates
Medulla
This part of the spinal cord contains axons in three columns (dorsal, lateral, ventral)
White matter
How does differentiation of the midbrain change after the initial steps?
It doesn’t change much after the initial steps
Secondary vesicles that form from the prosencephalon
Optic and telencephalon
Forms the nervous system and skin
Ectoderm
What is between the arachnoid and Pia mater?
CSF
These cells have processes projecting to the Pia that have a scaffolding function during cortical assembly in migration
Radial glial cells
Where is neurogenesis seen in rats?
Hippocampus
Spinal cord tracts often carry info in this way to or from the brain
Numerous tracts carry one way info to or from the brain
Replacing lipids in the brain with transparent water soluble gel to visualize deep structures without sectioning (only structural, not functional)
CLARITY
This is a relay center just like the midbrain
Hindbrain
Becomes skin under the influence of BMP. Nervous system develops bc of the protein chords blocking action of BMP in neural plate
Other ectoderm that isn’t the neuroectoderm
Forms muscles and skeleton
Mesoderm
Picture in this scan formed by freq being proportional to size of field and varying strength and direction of magnets being used to allow a computer to build a picture
Magnetic resonance imaging - MRI
Towards the front of the brain (forehead)
Anterior/rostral
Skull and forebrain degenerate, not compatible with life
Anencephaly
CT and MRIs are this kind of brain scan
Structural
Ventral of the midbrain becomes this
Tegmentum
Olfactory bulbs arise from these
Cerebral hemispheres
Swelling of the ventricles and head due to too much CSF
Hydrocephalus
What are the front of the brain and the top of the spine both anatomically? Why?
Anterior/rostral because the names for the brain differ from those for the body
Two cerebral hemispheres envelop this
Diencephalon
SLIDE 101
SLIDE 101
Forebrain neurons extended to form axonal bridges to connect the hemispheres
Corpus callosum
How does CSF flow?
From paired ventricles in the cerebrum to a series of unpaired cavities in the core of the brain stem
Hindbrain structure that receives large input from the spinal cord and pons, responsible for coordinated movement
Cerebellum
Forms the internal organs
Endoderm
Daughter cells migrate to pial surface in the MZ as a differentiated cell and cease further division (neurogenesis)
Cleavage in horizontal plane
This remains proportionate in primates
Cerebellum
This part of the hidbrain is continuous with the cerebral aqueduct
Fourth ventricle
This scan provides a pretty good structural view
Magnetic resonance imaging - MRI
First cells to migrate from VZ form this
Subplate
Adult neurogenesis in humans vs rats
Humans = maybe, rats = yes
Hindbrain structure that is a bundle of axons connected to the spinal cord
Medullary pyramids
How are the 4 ventricles connected?
Lateral ventricles in middle which surround the third ventricle, cerebral aqueduct connects them to the fourth ventricle near the cerebellum
An important really center in the cerebral cortex that uses the internal capsule
Thalamus
Subsequent cells in cortical plate form these after layer IV
Layer V, layer VI, etc
Has contralateral control (CNS)
Cerebrum
Allows for the movement of water in the BBB from these small pores
Aquaporins
Part of spinal cord projecting to ventral roots and on to muscle
Ventral horn
Relay center center in CNS
Brain stem
The tough meninges layer closest to the skull
Dura mater
Contains more neurons than glia
Cerebellum
Develops into somites which form the 33 vertebra and associated skeletal muscles
Mesoderm
Performs many higher functions like cognition, perception, and voluntary action
Forebrain
This part of the spinal cord contains the dorsal form, the intermediate zone, and ventral horn
Gray matter
Different sides
Contralateral
Will become what is also called the forebrain, eventually the telencephalon and diencephalon
Prosencephalon
Encased in vertebral column, its nerves are part of the PNS
Spinal cord (spinal nerves part of PNS)
Collection of neurons in the PNS
Ganglion
Systems for learning, speech, sensations, cognition, perceptions, voluntary movement, integration of many modalities
Cerebral cortex
This has expanded greatly in primates, humans 10x larger than in monkeys and 1000x greater than in mice
Cortex
What do many signaling molecules in the development of the nervous system influence?
Gene transcription
Areas in common ancestor of this area include primary sensory, secondary sensory, and motor
Cortex
Cut along the midline (divide to left and right)
Midsagittal
Axons which bypass the pons enter here (only 10%, 90% don’t bypass)
Medullary pyramids
Scan that labels active neurons, labels the ones using more oxygen
Functional MRI (fMRI)
Towards the bottom of the brain (near spinal cord)
Ventral
Plane that divides top and bottom
Horizontal/transverse
Carry motor function from axons which bring info from CNS to glands, muscles, etc
Efferent
Cells in the walls of this divide and become several structures
Telencephalon
Most primitive and essential for life CNS structure
Brain stem
Works by following water movement down axons (the diffusion rate and diffusion direction) axon bundles can be traced. Allows us to estimate the location and orientation of the brains white matter tracts in living people
Diffusion tensor imaging (DTI)
Excellent resolution (3 mm^3) and can detect changes that occur with 50 msec, allowing for measurement of brain changes that occur rapidly
Functional MRI (fMRI)
Transporters move ions, glucose, and metabolic waste out of this
BBB
Brodmann’s area 17
Vision
Regulates body temp, breathing, consciousness
Brain stem
How is CSF reabsorbed?
It exits the ventricular system, enters the subarachnoid space where it is absorbed by blood vessels
Rostral hindbrain (metencephalon) becomes these
Cerebellum and pons
These withdraw their processes once the cortex is formed in migration
Radial glia
Sensory spinal nerves
Dorsal roots
Thought different areas had different functions, but couldn’t prove it
Brodmann
Portion of NS that supplies motor and sensory innervation to structures that are not under voluntary control
Autonomic/visceral nervous system
Proliferation of cortical pyramidal neurons and astrocytes occur here
Dorsal region of the VZ
Type of cortex often just called the cortex, only in mammals, voluntary movement, vision, hearing, somatic sensation
Neocortex
This forms a pathway for information to the forebrain from spinal cord and vice versa
Midbrain
Forebrain structure with many old or basic functions, ANS, controls hormones by pituitary, body temp
Hypothalamus
Secondary vesicle from prosencephalon that becomes the retina and optic nerve part of the brain
Optic
This animal has a larger olfactory bulbs compared to humans
Rats
