Neuro - Cortical Organisation and Function Flashcards
What does the cerebral cortex cover?
The entire brain surface
What is the cerebral cortex made up of?
Grey matter continuous with deep nuclei, and is organised into lobes
What is present at the surface of the cerebral cortex?
Grey (outfoldings) and sulci (infolds)
What gives the cortex its grey appearance?
Neuronal cell bodies (nuclei)
How is the cortex divided up?
Into columns and rows, then into lobes
What are the layers of the cortex?
Molecular layer External granular External pyramidal Internal granular Internal pyramidal Multiform layer
How did Brodmann allocate cells for cytoarchitectural organisation?
Based on:
- Cell size
- Cell packing/spacing density
- Layers
How many regions are there for cytoarchitecture organisation?
52
What region make up the primary motor cortex?
4
What regions make up the primary somatosensory cortex?
1,2,3
What are the 4 main lobes of the brain + 2 other deeper lobes?
Frontal, Parietal, Occipital, Temporal
Limbic lobe, insular cortex
What is the role of the frontal lobe?
BLAMER: Behaviour Language Attention Memory Executive cognitive function Regulation and initiation off motor function
What is the role of the parietal lobe?
SSS
Sensation e.g. touch and pain
Sensory aspect of language
Spacial orientation/ self perception
What is the role of the occipital lobe?
Processes visual information
What is the role of the temporal lobe?
Emotion
Memory
Processing auditory information
What is the role of the limbic lobe?
Emotion, memory, learning, reward and motivation
What are the structures within the limbic lobe?
Mamillary bodies x2
Hippocampus
Amygdala
Cingulate gyrus
Where is the insular cortex found?
Deep inside to the lateral fissure - it has gyri and sulci on its surface
What is the role of the insular cortex?
AVIVA: Autonomic control Visceral sensation Interception Visual-vestibular integration Auditory processing
What makes up grey matter?
Neuronal cell bodies and glial cells
What makes up white matter?
Myelinated neuronal axons arranged in tracts
Is all grey matter cortical?
No, some grey matter is found within the deep nuclei which are continuous with cortical grey matter
What are the three white matter tract types?
Association fibres
Commissural fibres
Projection fibres
What are association fibres?
Connect areas within the same hemisphere
What make up association fibres?
Long and short fibres
What are the 4 association fasciculi (long fibres)?
Arcuate - frontal + temporal
Superior longitudinal - Frontal + occipital
Inferior longitudinal - Temporal + occipital
Uncinate - Anterior frontal + occipital
What are commissural fibres?
Connect homologous structures of the left and right hemispheres
What are the 2 commissural fibres?
Corpus callosum
Anterior commissure
What is the surgical significance of the corpus callosum?
Can be surgically disconnected in the case of epilepsy to prevent inter lobe overactivity
What are projection fibres?
Connect cortex with lower brain structures e.g. thalamus, brain stem and spinal cord
What are afferent/efferent fibres?
Afferent = towards cortex. Efferent = away from cortex
What is the corona radiata?
A white matter sheet formed from the projection fibres that compresses as we move towards the spinal cord
Where do the projection fibres converge through?
Thalamus and basal ganglia within the internal capsule
What is the basic difference between primary and secondary cortices?
Primary receives the basic information but secondary takes said information and adds meaning/complexity to it
What are the specific differences between primary and secondary cortices?
Function: 1 is predictable, 2 is unpredictable
There is topographic orientation in 1, not in 2.
There is left-right symmetry in 1, not in 2
What is the role of the supplementary area?
Although descending signals originate in the primary motor cortex, the supplementary are is concerned with the planning of complex movement that is internally cued e.g. speech
What is the role of the premotor area?
Planning complex movement that is externally cued for example seeing a cup of coffee and picking it up
What does the primary somatosensory cortex receive? (6)
Fine touch Proprioception Temperature Pain Vibration two-point discrimination
What does the somatosensory association cortex do?
Processes the significance of information and adds meaning to it. It also has a role in self perception and personal space
What does the primary visual cortex do?
Receives visual stimuli
What does the visual association area do?
Gives meaning and interpretation to the visual input
What does the primary auditory cortex do?
Receives auditory stimuli
What does the auditory association cortex do?
Gives meaning and interpretation to the auditory stimuli
What is the role of Broca’s area?
Found in the left frontal lobe - involved in the production of speech
What is the role of Wernicke’s area?
Found in the left temporal lobe - involved in the interpretation of speech
Lesion to frontal cortex?
Change in personality and inappropriate behaviour due to prefrontal cortex damage
Lesion to Broca’s?
Expressive aphasia
Lesion to parietal lobe?
Contralateral neglect - lack of internal and external awareness on side opposite to lesion
Lesion to temporal?
Agnosia - inability to recognise/ anterograde amnesia - inability to form new memories
Lesion to Wernicke’s?
Receptive aphasia
Lesion to primary visual?
Blindness in corresponding part of visual field
Lesion to visual association area?
Interpretation deficit for vision - e.g. prosopagnosia (inability to recognise/learn familiar/new faces)
What imaging can we use for cortical function?
PET or fMRI
What does PET do?
Uses radioactively labelled glucose to measure blood flow going directly to the brain
What does fMRI do?
Measures the level of blood oxygen that is in a brain region
What is EEG?
Electroencephalography - measures brain’s produced electrical signals in response to an evoked potential
What is MEG?
Magnetoencephalography - measures the magnetic signals produced by the brain in response to an event-related/evoked potential
What is the role of somatosensory evoked potentials e.g. median nerve stimuli?
We can use different probes around the body, e.g. at the wrist where the stimuli originates, at the shoulder, at the spinal cord, at the thalamus and at the cortex to see if there is any delay in the impulse travelling to the somatosensory cortex.
What does brain stimulation do?
Assesses the functional integrity of neural circuits in theb brain by stimulating neurones
What is TMS?
Transcranial magnetic stimulation - can stimulate neurones to produce an output e.g. muscle movement in hand
What can brain stimulation/TMS be used for?
Investigate neuronal interaction controlling movement e.g. after a spinal cord injury.
We can see if a particular area of the brain maps to a particular function
What is tDCS?
Transcranial direct current stimulation - low direct current over the scalp can be used to increase or decrease neuronal firing rates
What is DTI?
Diffusion Tensor Imaging - based on water molecule diffusion.
What is DTI w/tractopgraphy?
DTI can be used to illustrate tracts such as the corona radiata
What is the role of the prefrontal cortex
DAPPA:
Decision making Attention Planning Personality expression Adjusting social behaviour
