Lecture 2 - Neuroanatomy Flashcards
What % of brain cells are neurons?
10%
How many neurons approx do we have and how many do they connect to in turn?
Approx 100 billion that connect to 10,000 each
How often do we lose cortical neurons ?
1 per second
What is white matter made up of?where can it be found?
Myelinated axons and supporting glia cells
Found underneath the cerebral cortex grey matter
If you have the side view of the brain, how would you describe the front and the back, what terms would you use?
Front : anterior (so that would be prefrontal cortex)
Back : posterior ( so that would be occipital cortex)
Side view of the brain, what terms do you use to describe the top and bottom ?
Superior : top ( so that would be near the parietal )
Inferior : bottom ( so that would be like temporal/ basic brain structures)
How do you describe the navigational line from the corpus calloused out to the outer part of the brain?
if you were looking at it sideways it would be the axis that comes out towards you
Medial to lateral
If you are shown a side on slice of the brain, what would you call that?
Sagittal slice
If you were shown a slice of the brain of someone who was looking you in the eyes what would you call it?
Coronal view
If you were shown brain slices from the top of the head down to the spine. What would you call it ?
Axial view
What are the 4 main sulci?
Longitudinal fissure
Central sulcus
Lateral sulcus (Sylvian fissure)
Parieto-occipital sulcus
What do these four main sulci delineate?
They delineate the 4 main lobes of the brain, temporal, parietal, occipital and frontal.
Which fissure is thought to delineate v1, v2, v4?
Calcarine fissure
What are the names of two big neuroanatomists?
Campbell
Brodmann
What did brodmann do ?
Using a staining technique (Nissl stain) he looked at the cytoarchitecture of the brain and found 52 distinct areas of the brain.
He wanted to not just look at the gross anatomy of the brain but what the main gyri and sulci were comprised of
What is laminar?
Laminar means layers, brodmann found 6 different layers each containing different types of neurons which were paced differently for each section of the brain.
E.g. The visual areas are very tightly packed whereas motor layers are more spread out.
What is a fasciculus?
White matter fibre tract
Is the white matter organised or just a random bunch of connections ?
Organised.
Can be split into 4 major tracts
What are the 4 major white matter tracts?
Superior longitudinal fasciculus
Uncinate
Inferior fronto-occipital fasciculus
Cingulum
What are the three broad categories of white matter tracts called? What do they connect?
Association tract - links cortical within hemisphere
Projection tract - cortical to subcortical (like cerebellum and basal ganglia)
Commissure - cortical between hemisphere
Marner et al (2003) took a tiny portion of white matter fibres and counted the number of myelin sheaths within this section. They did this for both males and females ranging between 20 years and 100 years.
What did they find?
What did they conclude?
Marner et al found that as age increased the number of myelin sheaths (amount of nerve fibre per km) decreased significantly.
They concluded that anatomical fibre integrity is linked to performance on cognitive tasks like memory and therefore, that’s why as you get older your performance worsens.
Scholz (2009) taught his participants to juggle in a 6 week programme. They had brain scans, before, after the 6 weeks and again after 6 months.
What did they find?
Found 6% increase in white matter health in the visuo-spatial area of the brain.
This increase remained for 6 months after the study as well.
What is the standard brain space?
A technique used to compare individuals brains that will all be slightly different shapes and sizes
Name 2 types of standard spaces
Talairach
MNI (Montreal neuro institute)
How does talairach differ from MNI?
MNI is an average of about 152 brains, which you then use the anterior commissure as coordinates (0,0,0) and align the new brain to it.
Talairach only used on standard brain and mapped the scans brains onto it.
Describe 5 important parts of a neuron
- Dendrites - receive messages from other neurons
- Soma - cell body, grey matter
- Axon - transmits messages along
- Myelin sheath - speeds up transmission, protects axon from damage, white matter
- Nodes of ranvier - gaps in the myelin sheath, allows for passive conduction
