4-6 Organization of the Cerebral Cortex Flashcards
What does the prosencephalon give rise to?
Telencephalon
Diencephalon
What does the rhombencephalon give rise to?
Metencephalon
Myelencephalon
What does the Mesencephalon give rise to?
Mesencephalon again, then midbrain
What does the metencephalon give rise to?
Cerebellum
Pons
What does the diencephalon give rise to?
Thalamus
Hypothalamus
Retina
What does the myelencephalon give rise to?
Medulla
What does the telencephalon give rise to?
Cerebral cortex
Basal Ganglia
What 2 developmental structures does the allocortex give rise to? What 2 adult structures? What structure was its embryological precursor?
Allocortex: fewer layers than neocortex
- Archicortex - hippocampus
- Paleocortex- olfactory cortical areas
Originally part of telencephalon, along with neocortex
What 6 events, from conception to birth, create cortical development?
- Neurulation
- Neuronal proliferation
- Neural migration
- Apoptosis
- Synaptogenesis
- Myelination
Large pyramidal neurons can be found where?
Motor cortex
Small pyramidal neurons can be found where?
Sensory cortices
When does cortical synaptogenesis occur? What follows shortly after?
Just after birth
Synaptic pruning and apoptosis follows
When do the following events end:
neuronal proliferation
neural migration
synaptogenesis
synaptic pruning
myelination
neuronal proliferation - 12 weeks gestation
neural migration - birth
synaptogenesis - adulthood
synaptic pruning - adulthood
myelination - adulthood
What NTs do cortical synapses use? What does this mean in terms of development?
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
Where are most synapses formed in the postnatal period?
Association cortices
Sensory system primarily ‘blank’ until synapses in association cortices form
What is the difference between unimodal and multimodal association cortices?
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
What are some areas of rapid cortical development for a young (<5 yo) child?
Lateralization, especially in temporal and parietal areas
- handedness
- Broca’s area
- Wernicke’s area
Why are Brodman’s areas a thing?
Mostly to torture us
Also, Brodman’s areas show significant histological differences from each other, which is indicative of underlying function
How are brains lateralized for language and speech?
Language exists bilaterally:
Left hemisphere is logic
Right hemisphere is emotion
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?
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”.)
Which hemisphere is your lying hemisphere? What is the right hemisphere good at processing, generally?
Left: “lying” - comes up with stuff for gaps in information, processes logic
Right: shapes, 3D objects, art, music, emotions
Myelination continues until _____? How does it influence neuronal growth?
Myelination continues into adulthood
Myelination is generally inhibitory to neuronal growth, or addition of new cortical layers
Where do association fibers go? What are 2 major association fibers?
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
Where do commissural fibers go?
Links matching areas of 2 hemispheres
Makes up corpus callosum
Anterior white commissure
Where do projection fibers go? What are 2 major association fibers?
Run to subcortical nuclei
Parts include:
Corona radiata
Internal capsule
Crus cerebri
Pyramids
Where does most of the myelination happen in the postnatal period?
Association cortices
Reticular formation
Where does the reticular formation project? Why? What are the clinical implications of this?
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
