L3 - 4

Question 1

Pre-central sulcus controls? Post?

Answer 1

Movement and planning

Sensation and perception

Question 2

Obvious fissure is

Answer 2

Sylvian fissure aka lateral sulcus (central sulcus is hard to distinguish)

Question 3

PFC is innervated by

Answer 3

Medio-dorsal nucleus

Question 4

2 main types of multipolar neurons found in cerebral cortex

Answer 4

Pyramidal - primary excitation units of the mammalian prefrontal cortex and the corticospinal tract.

Stellate - star-like shape formed by dendritic processes radiating from the cell body

Question 5

90% of neocortex has 6 layers (aka isocortex) - how many does allocortex have?

Answer 5

3 to 5 cell layers (around the edges of the brain)

Question 6

Nissl stains bind to highly +ve or -ve charged structures?

Answer 6

-ve, e.g. Ribosomes and DNA hence you tend to just label cell bodies

Question 7

_% of neurons in cerebral cortex are excitatory, _% are inhibitory - these include _ basic types and many subtypes

Answer 7

80%, 20%, 3 (interneurons)

Question 8

Excitatory neurons within cortex project where?

Answer 8

Intra-telencephalic (telencephalon develops into cerebral cortex and basal ganglia) - project locally, across gyri, to other cortical areas and are only ones to project contralaterally

Question 9

Excitatory neurons outside cortex project where?

Answer 9

Pyramidal tract neurons that project to brainstem, midbrain and spinal cord

Cortico-thalamic neurons project to ipsilateral thalamus

Question 10

Is there an iterative (frequent repetition) unit of the cerebral cortex?

Answer 10

No - there is no consistency in what would unambiguously define a column in different regions of the cortex

Question 11

Neocortex has 6 layers - what are they?

Answer 11

1) Aneuronal (neuropil - a dense network of interwoven nerve fibres and their branches and synapses, together with glial filaments)
2) Interneurons (EXT granular layer)
3) Pyramidal cells (EXT pyramidal)
4) Interneurons (INT granular)
5) Large pyramidal neurons (INT pyramidal)
6) Heterogeneous neurons (multiple form layer)

Question 12

Cluster analysis

Answer 12

Placing things into different groups

Question 13

Principle components analysis (PCA)

Answer 13

Statistical procedure that uses an orthogonal transformation to convert a set of observations of possibly correlated variables into a set of values of linearly uncorrelated variables called principal components.

It emphasizes variation and bring out strong patterns in a dataset. It’s often used to make data easy to explore and visualize.

Question 14

Structure of a minicolumn

Answer 14

• 20-40 um wide
• Vertical column through the layers of the brain
• Contains 80-120 cells (twice as much in visual cortex)
• Bundles together dendrites
• Afferent signal enters at layer IV of the minicolumn and spreads up and down

Question 15

If you look at orientation of the cortex orthogonally, orientation sel. is the same/diff?

Answer 15

Same

Question 16

What is the main difficulty when approaching exp regarding columns?

Answer 16

Bias- many investigators have sought to detect and characterize the column, rather than make an unbiased analysis of the evidence for and against them

Question 17

2 Phases of the blue brain project

Answer 17

1) Dissect microanat, genetic, electrical properties of neocortical column
2) Use that data to make simulations of the behaviours of those elements

Question 18

What is a connectome?

Answer 18

The set of all connections in a brain, or sub-region.

- 10^15 connections in the human brain

Question 19

Given that there might be 1-^15 connections in the human brain, we might need to look at bigge,r less detailed pictures of connectivity. Scales to consider?

Answer 19

• Macro-scale (whole brain connectivity)
• Meso-scale (interconnections between regions of neurons)
• Micro-scale (every synapse, in their synaptic variety)

Question 20

What does the term “big data” cover?

Answer 20

Covers not only BIG but COMPLEX data sets: high-dimensional, distributed and heterogamous

Question 21

What does MRI tractography exploit? What scale is it using?

Answer 21

Water movement is less restricted in the direction of fibre tracts.

Macro scale

Question 22

What do we use to see things on a meso-scale? ________ methods provide a means of detailed mapping of projections between small (meso-scale) regions of the NS. It is an invasive/non-invasive method, requiring the brain to be harvested and histologically analysed

Answer 22

Light microscope, tract tracing, invasive

Question 23

Dimensionality reduction

Answer 23

The process of reducing the number of random variables under consideration, via obtaining a set of principal variables

• Summarise connectivity in a skeletal way
• Rather than represent synapses with 100s of kilobytes of data, just make a connectivity graph e.g. this neuron connects to this other neuron through 4 synapses
• It is a structural map, not a functional way
• As we get down to scale, we reduce scope

Question 24

Blue brain project
Completion – 2 week old rat somatosensory cortex segment (2mm tall, 210 um in radius)
-1009 cells are completely digitally reconstructed in 3-D
-55 morphological classes (42 GABAergic, 13 Glutamergic types)
-Electrical properties of these neurons are inferred by recording from the cell bodies
-Inferred 207 morpho-electrical types
-Next, populate the column with 31, 320 neurons from these 207 types with multiple clones of each cell type randomly distributed across the 5 layers in accordance with measured cell densities and immune-histochemical staining data
-Then apply the synapse algorithm

Answer 24

Blue brain project
Completion – 2 week old rat somatosensory cortex segment (2mm tall, 210 um in radius)
-1009 cells are completely digitally reconstructed in 3-D
-55 morphological classes (42 GABAergic, 13 Glutamergic types)
-Electrical properties of these neurons are inferred by recording from the cell bodies
-Inferred 207 morpho-electrical types
-Next, populate the column with 31, 320 neurons from these 207 types with multiple clones of each cell type randomly distributed across the 5 layers in accordance with measured cell densities and immune-histochemical staining data
-Then apply the synapse algorithm

Question 25

Buxhoeveden and Casonova conclude - minicolumn = strong model for cortical organization and is the most basic and consistent template by which the neocortex organizes its neurons, pathways and intrinsic circuits

Answer 25

Buxhoeveden and Casonova conclude - minicolumn = strong model for cortical organization and is the most basic and consistent template by which the neocortex organizes its neurons, pathways and intrinsic circuits

Question 26

T/F - Each region of the cerebral cortex has projections to the same region of the opposite hemisphere, and to and from distinct sub-regions of the thalamus

Answer 26

T

Question 27

What is piriform cortex (3 layers) involved in?

Answer 27

Olfactory processing region

Question 28

T/F - Blue brain project: the neurophysiology and morphology of each neuron, and the synaptic physiology of all its connections, are simulated for every neuron in a single column of mouse cerebral cortex.

Answer 28

T

Question 29

Can info from one column transfer info to another at boundary response fields?

Answer 29

Yes

Question 30

What do we know about columns?

Answer 30

Exist
No uniform standard iterative unit
Vague definition
Uncertain role
Not readily identifiable
Unknwon processes occuring within
Vary across cortex
Does not correspond to known dimensions of thalamic input

Question 31

How many layers does hippocampus have? Enthorhinal cortex? Insula? Cingulate?

Answer 31

3, 3 to 4, 4 to 5, 5