Cerebral Cortex Flashcards
What is a primary area in regards to the cerebral cortex?
Areas that have paired/matching areas in each lobe & or each hemisphere
What is functional contra-laterality?
To control events happening on the other side of the body
Define topography
The act of mapping an area
What are Secondary/Association areas in regards to the cerebral cortex?
Areas present in only one hemisphere
What is cerebral dominance/Functional asymmetry?
the normal tendency for one side of the brain to control particular functions e.g. left cerebral cortex is devoted to language functions whilst the right cerebral function is devoted to spatial awareness/attention.
What are the four primary cortical areas and where are they present?
Primary Somatosensory (S1) Cortex – It is present in the L & R parietal lobes
Primary Motor (M1) Cortex - It is present in the L & R frontal lobes
Primary Auditory (A1) Cortex - It is present in the L &R temporal lobes
Primary Visual (V1) Cortex - It is present in the L & R occipital lobes
Where is the Primary Somatosensory (S1) cortex found?
In the post central gyrus which is next to the central sulcus.
Define unilateral
relating to or affecting only one side of an organ, the body, or another structure.
What does unilateral damage of the Primary Somatosensory (S1) cortex cause?
Unilateral damage results in hemi-anaesthesia (loss of tactile, thermal, pain & joint sensation)- in this case on the opposite side of the body.
What is a topographic representation (a.k.a a map) of the Primary Somatosensory cortex (S1) called?
Sensory Homonculus.
(Size of body parts is proportionate to the sensory input they give out).
(The toe side is medial and the face side is lateral)
What are characteristic features of the Sensory Homonculus ?
Inverted (as it goes in order of genitals and feet to mouth nose and eyes)
&
Distorted ( distorted because size of regions is proportional to input recieved by that region e.g. fingertip region is drawn larger as it is a high density sensory neuron area)
Why is the pre-central gyrus called the pre-central gyrus?
It is infront of the central sulcus.
What does unilateral damage of the Primary Motor (M1) cortex result in?
Hemi-plegia (paralysis) - this occurs on the opposite side of body)
What is a topographic representation (a.k.a a map) of the Primary Motor (M1) cortex called?
Motor Homonculus
What are characteristics of the Motor Homonculus and why?
It is inverted
and
distorted ( the size of each body part is proportional to the number of muscles it has).
Where is the Primary Motor (M1) Cortex found?
In the Frontal lobe - more specifically the Pre-central gyrus
What is the Primary Motor (M1) cortex responsible for?
The primary motor cortex function is respponsible for generating the neural impulses that are required for the execution of motor activities in the human body.
How do different Primary Areas acquire their different functions?
Via long-range axon pathways that relay in the THALAMUS.
So basically in the thalamus there are 4 different main nuclei - VP, VL,MG and LG.
What these four diff main nuclei do is send impulses down different paths.
So basically you would have impulses picked up e,g, from the skin which would have travelled along the spinal chord to the thalamus- these impulses would be picked up by the Ventral Posterior Nuclei (in the thalamus) and sent to S1 (Somatosensory cortex). To be dealt with accordingly.
(The picture attached shows the pathways - at each box before you get to the relevant cortex - you cross a synapse)
Why do Primary Areas deal with only the opposite side of the body/space?
Because axons crossover somewhere along midline (a.k.a. ‘decussate’) once, somewhere along their pathway in the CNS
Are there anatomical differences between different Primary Areas that relate to their Functional Specialization?
Yes there are subtle differences in their cellular structure (- these are called ‘cyto-architecture’)
What is the parietal lobe and occipital lobe seperated by?
The parieto-occipital sulcus (as can be found and seen in the picture)
Where is the Primary Visual (V1) cortex found?
In the gray matter of the calcarine sulcus , in the occipital lobe.
Where is the calcarine sulcus found and what does it anatomically do?
It is found about 90 degrees to the parieto-occipital sulcus and it splits the occiptial lobe in two ( as can be seen in the picture).
What does the Primary Visual (V1) cortex map hold information on and what does it look like?
The primary Visual Cortex (V1) holds a map of the oppoiste half of your visual field (i.e. hemi-field).
This map is INVERTED (the top of V1 contains a map of your lower visual field and the lower part of V1 contains a map of your higher visul field)
and
DISTORTED (large region for fovea and macula- remember these contain a high number of photoreceptors and retinal ganglia cells (when compared to periphery))
