Cerebral Cortex Flashcards
Which structures of the brain connect the cerebral hemispheres ?
Corpus callosum - larger white matter region and anterior commisure
How many neurons are present in human cerebral cortex ?
10 to the power of 10 neurons
What is the function of the precentral gyrus?
It is important in motor control and is just in front of the central sulcus
What is the function of the post central gyrus ?
It is important in somatosensory control and is just behind the central sulcus
What is Brodmann areas ?
It is the histological analysis of the cortex based on the laminar distribution
The neocortex has 6 layers
Which laminae are important for sensory input ?
Lamina 4
What laminae is important for motor input ?
Laminar 5
What are some of the key areas of the subdivisions of the cerebral cortex ?
Post central gyrus - for somatosensory input
Primary motor cortex/precentral gyrus- for fine motor control
Visual cortex- for conscious visual sensation
Auditory cortex - for auditory sensation
Broca’s area- for speech production
What do the layers if the cerebral cortex look like ?
Layer 1- has few cells
Layer 2 and 3- contain small pyramidal cells which project to other cortical regions
Layer 4- contain large stellate cells which receive massive inputs from the thalamus telling us sensory info
Layer 5- contain large pyramidal cells with very long projecting axons which make them major output cells
Layer 6- contain pyramidal cells that project to the thalamus providing an output for the thalamus
What are basket cells like ?
They can innervate different layers or can remain confined to a single layer
They are inhibitory
What are EEGs and explain the different waves ?
They measure the electrical activity of a large group of neurons in the cortex
- delta waves = low frequency and are active during deep sleep (<4hz)
- theta waves = slightly higher frequency which are active during sleep (4-7hz)
- alpha waves = slighter higher frequency again and here are active when your awake but relaxed (8-13hz)
- beta waves = higher frequency again and these are active during mental activity (13-20hz)
What is CT imaging ?
Uses x rays which are fired at several angles
Computer constructs a 3d image
Exposure to radiation
Non functional imaging
What is MRI imaging ?
Uses strong magnetic fields and radio waves to produce images based on hydrogen content of body tissue- water
No radiation.
Non functional imaging
What is PET pane fMRI imaging ?
Functional imaging
It detects changes in the brain metabolism and blood flow
Active neurons require more oxygen/glucose and so brain blood vessels work by increasing the blood flow to these neurons
How much of the cerebral cortex is made up of the association cortex and what is it’s function ?
75%
Important for integrating info received from other brain regions
It is very large in humans
Inputs: main one is the CORTICO-CORTICAL CONNECTIONS. Others include primary/secondary sensory and motor cortices, other association areas in both hemisphere and the thalamus and brainstem
Outputs: hippocampus, basal ganglia/cerebellum, thalamus etc
What is the flow of connections of cortical areas ?
Primary sensory areas Higher sensory areas Association areas Premotor areas Primary motor area - these then activate the CORTICO-spinal outputs to innervate muscles
What is contra lateral neglect syndrome ?
It is the inability to attend to objects in space
The patients deny the existence of the side of the body opposite to lesion
What is prospognosia?
Face blindness - caused by lesions to the temporal lobe
What are the symptoms of Broca’s aphasias ?
Halting speech Repetitive Disorder syntax Disordered grammar Disordered structure of words
What are the effects of wernickes aphasias ?
Fluent speech Little repetition Syntax adequate Grammar adequate Contrived or inappropriate words
They can understand the language spoken to them but struggled producing speech
Explain bilingualism ?
If you learn more than one language while you are young then the speech areas overlapping for both languages I strongly lateralised
If you learn another language after about 8/9 years old then then the speech areas are non overlapping so there is less lateralisation
What is “split brain” and what is it used to treat ?
It is the surgical separation of the right and left hemispheres of the brain
It is used to treat epilepsy to try and prevent the spread of seizures from one hemisphere to the other,
Where is language specialisation mainly in the brain ?
It is mainly in the left cerebral hemisphere
Therefore if a person has “split brain” surgery for epilepsy they can easily name objects in heir right hands but struggle to name objects in their left hands
