Cortical Organisation And Function Flashcards
What is the cerebral cortex?
Covers entire surface of brain
Contains grey matter
Gyri and sulci
Organised into lobes
Organised into layers and columns (don’t really need to know). Classification by this sorts it into 52 regions based on cyto architecture
What are the lobes of the brain?
Frontal
Parietal
Temporal
Occipital
What does the frontal lobe do?
Regulates and initiates motor function (contains primary motor cortex)
Language
Executive cognitive function (eg. Planning)
Attention
Memory
Decision making
What is the parietal lobe?
Sensation- touch, pain
(Contains primary somatosensory cortex)
Sensory aspects of language
Spatial orientation and self perception (interoception)
What is the occipital lobe ?
Processes visual information - ascribes meaning to visual images
What is the temporal lobe?
Processes auditory info
Emotions
Memories
(It sits below the lateral fissure)
What is the limbic lobe?
Curly bit below the cortex that can be seen in a saggital section
Includes the amygdala, hippocampus, mammillary body, and cingulate gyrus
Learning Memory Emotion Motivation Reward
What is the insular cortex?
Lies deep within the lateral fissure
Visceral sensations Autonomic control Interoception Auditory processing Visual-vestibular integration
What is the internal structure of the cerebral cortex? (What’s it made of)
Grey matter (peel) - Neuronal cell bodies and glial cells (~85 bil of each)
White matter -
Myelinated neuronal axons arranged in tracts
What are white matter tracts? And what are their types?
They connect cortical areas
Association fibres - connect areas within the same hemisphere
Commissural fibres - connect homologous structures in the left and right hemisphere
Projection fibres - connect cortex with lover brain structures (eg. Thalamus, brain stem, spinal cord)
Detail on association fibres? Eg?
Connect ares in the Same hemisphere- never cross to other side
Long fibres - eg. Superior longitudinal fasciculus connects frontal and occipital
Bendy fibres - eg. Uncinate fasciculus connects frontal and temporal lobes
Short fibres
arcuate fasciculus connects wernicke and brocas areas
Look up a photo, very helpful
Commissural fibres detail? Eg?
Connect homologous structures in left and right hemisphere
Eg. Corpus callosum and anterior commissure
Projection fibres detail? Where do they converge?
Connects cortex with lower brain structures
Afferent - towards cortex
Efferent- away from cortex
Deeper to cortex radiate as the corona radiata
Converge through internal capsule between thalamus and basal ganglia
What are the difference between primary and secondary/association cortices?
Primary:
Function predictable
Organised topographically
Left and right symmetry
Eg. Primary somatosensory cortex
Secondary:
Function less predictable
Not organised topographically
Left right symmetry weak/absent
Eg. Language centres - wernicke and broca - only on one side
What are the motor areas contained in the frontal lobe?
Primary motor cortex:
Fine, discrete, precise voluntary movement
Provides descending signals to execute movement
Supplementary area:
Involved in planning complex movements (internally cued)
Eg. Speech
Premotor area:
Involved in planning movements (externally clued)
Eg. Seeing an object you want to pick up
What are the sensory areas located in the parietal lobe?
Primary somatosensory cortex:
Processes somatic sensation arising from receptors in the body
Eg. Light touch, vibration, proprioception, pain, temp
Somatosensory association area:
Interprets significance of sensory info
Eg. Recognising an object
Awareness of self and personal space
What are the visual areas located in the occipital lobe?
Primary visual:
Processes visual stimuli
Visual association:
Gives meaning and interpretation of visual input
What are the auditory areas located in the temporal lobe?
Primary auditory:
Processes auditory stimuli
Auditory association:
Gives meaning and interpretation of auditory input
Which association areas are concerned with language?
Broca’s area:
Production of language
Wernickes area:
Understanding of language
These are often on the left side of the brain
Also are connected by the arcuate fasciculus
What does the prefrontal cortex of the brain do? (Phineas gage)
Attention Adjusting social behaviour Planning Personality expression Decision making
Eg. When this is damaged like in the case of phineas gage it’s like people are no longer themselves at all
Lesions here change personality and lead to inappropriate behaviour
What is the result of parietal lobe lesions?
Contralateral neglect
Internal and external
Eg. Lesion in left hemisphere
Lack of awareness of self on right side (might forget to put that arm through a sleeve, or shave that side)
Lack of outside awareness on right side (might only fill half their plate, or only be able to copy the left side of an image)
What is the result of temporal lobe lesions?
Leads to agnosia- inability to recognise
Eg. With patient HM, bilateral resection of anterior medial temporal lobe structures to cure epilepsy. Couldn’t form new memories - anterograde amnesia
What is the result of lesions in wernicke and Broca’s areas?
Brocas:
Expressive aphasia- poor production of speech. But can comprehend
Wernickes:
Receptive aphasia- poor comprehension of speech. Production is fine
What is the result of lesions to the visual areas in the occipital lobe?
Primary visual cortex:
Blindness in the corresponding part of the visual field
Visual association area:
Deficits in interpretation of visual info
Eg. Prosopagnosia- can’t recognise familiar faces or learn new ones
How can cortical function be assessed using imaging?
PET - positron emission tomography:
A radioactive marker is attached to glucose, this appears more red in active areas of the brain due to increased blood flow to these areas
fMRI - functional MRI:
Areas in use appear red due to blood oxygen in that brain region
How can cortical function be assessed using encephalography?
EEG - electroencephalography:
Measures electrical signals produced by the brain
It’s that funny hat looking thing
Specific places to put each electrode that the technicians work out using percentages of head proportions
Can be used to measure movement of a stimuli along a pathway (eg. Somatosensory) by playing electrodes along that pathway and seeing how the electrodes are sequentially activated
Magnetoencephalography:
Measured magnetic signals produced by brain
Newer
Transcranial magnetic stimulation:
Assess integrity of neural structures
Uses electromagnetic induction to stimulate neurones, this may then produce an (eg. Motor) output
A couple more newer ones, look at session pp
