4-6 Organization of the Cerebral Cortex

Question 1

What does the prosencephalon give rise to?

Answer 1

Telencephalon

Diencephalon

Question 2

What does the rhombencephalon give rise to?

Answer 2

Metencephalon

Myelencephalon

Question 3

What does the Mesencephalon give rise to?

Answer 3

Mesencephalon again, then midbrain

Question 4

What does the metencephalon give rise to?

Answer 4

Cerebellum

Pons

Question 5

What does the diencephalon give rise to?

Answer 5

Thalamus

Hypothalamus

Retina

Question 6

What does the myelencephalon give rise to?

Answer 6

Medulla

Question 7

What does the telencephalon give rise to?

Answer 7

Cerebral cortex

Basal Ganglia

Question 8

What 2 developmental structures does the allocortex give rise to? What 2 adult structures? What structure was its embryological precursor?

Answer 8

Allocortex: fewer layers than neocortex

1. Archicortex - hippocampus
2. Paleocortex- olfactory cortical areas

Originally part of telencephalon, along with neocortex

Question 9

What 6 events, from conception to birth, create cortical development?

Answer 9

1. Neurulation
2. Neuronal proliferation
3. Neural migration
4. Apoptosis
5. Synaptogenesis
6. Myelination

Question 10

Large pyramidal neurons can be found where?

Answer 10

Motor cortex

Question 11

Small pyramidal neurons can be found where?

Answer 11

Sensory cortices

Question 12

When does cortical synaptogenesis occur? What follows shortly after?

Answer 12

Just after birth

Synaptic pruning and apoptosis follows

Question 13

When do the following events end:

neuronal proliferation

neural migration

synaptogenesis

synaptic pruning

myelination

Answer 13

neuronal proliferation - 12 weeks gestation

neural migration - birth

synaptogenesis - adulthood

synaptic pruning - adulthood

myelination - adulthood

Question 14

What NTs do cortical synapses use? What does this mean in terms of development?

Answer 14

GABA or glu

These NTs need to be recycled by astrocytes, which aren’t made until later stages of gestation.

Also, GABA and glu tend to have opposite effects in infants than in adults

Question 15

Where are most synapses formed in the postnatal period?

Answer 15

Association cortices

Sensory system primarily ‘blank’ until synapses in association cortices form

Question 16

What is the difference between unimodal and multimodal association cortices?

Answer 16

Unimodal - elaborates on basic information in primary sensory cortex

Multimodal - connects multiple sensory modalities, higher level intellectual functions

• allows for new understanding of sensory info, or linking several types of sensory inputs

Question 17

What are some areas of rapid cortical development for a young (<5 yo) child?

Answer 17

Lateralization, especially in temporal and parietal areas

• handedness
• Broca’s area
• Wernicke’s area

Question 18

Why are Brodman’s areas a thing?

Answer 18

Mostly to torture us

Also, Brodman’s areas show significant histological differences from each other, which is indicative of underlying function

Question 19

How are brains lateralized for language and speech?

Answer 19

Language exists bilaterally:

Left hemisphere is logic

Right hemisphere is emotion

Question 20

What does the left and right inferior frontal gyrus add to speech? Left and right superior temporal gyrus? What does a lesion in each of these areas result in?

Answer 20

Left inferior frontal gyrus: creation of speech from neural input

• lesion: Broca’s aphasia

Right inferior frontal gyrus: add emotional inflection to speech

• lesion: flat speech

Left superior temporal gyrus: Processing of sensory input into appropriate speech

• lesion: Wernicke’s aphasia

Right superior temporal gyrus: understanding of emotional content of speech

• lesion: (Leia: “I love you”. Luke: “I know”.)

Question 21

Which hemisphere is your lying hemisphere? What is the right hemisphere good at processing, generally?

Answer 21

Left: “lying” - comes up with stuff for gaps in information, processes logic

Right: shapes, 3D objects, art, music, emotions

Question 22

Myelination continues until _____? How does it influence neuronal growth?

Answer 22

Myelination continues into adulthood

Myelination is generally inhibitory to neuronal growth, or addition of new cortical layers

Question 23

Where do association fibers go? What are 2 major association fibers?

Answer 23

Pass from one part of a single hemisphere to another

Superior longitudinal/arcuate fasciculus - connects inferior frontal gyrus to superior temporal gyrus, have a big fiber connection between Broca’s and Wernicke’s area

• makes up area around Sylvian sulcus called parasylvian language area

Uncinated fasciculus - cortical area to temporal lobe

Question 24

Where do commissural fibers go?

Answer 24

Links matching areas of 2 hemispheres

Makes up corpus callosum

Anterior white commissure

Question 25

Where do projection fibers go? What are 2 major association fibers?

Answer 25

Run to subcortical nuclei

Parts include:

Corona radiata

Internal capsule

Crus cerebri

Pyramids

Question 26

Where does most of the myelination happen in the postnatal period?

Answer 26

Association cortices

Reticular formation

Question 27

Where does the reticular formation project? Why? What are the clinical implications of this?

Answer 27

Projects widely to neocortex

Regulates dynamic brain states, including sleep

Children, with varying degrees of myelination of the reticular formation, will have significantly different sleep cycles and EEGs