1b Cortical Organisation and Function Flashcards
What is the cerebral cortex?
The thin layer that covers the entire surface of the brain - together with deep nuclei contains the grey matter
What are the layers in the microscopic organisation?
Molecular layer
External granular layer
External pyramidal layer
Internal granular layer
Internal pyramidal layer
Multiform layer
What is the cytoarchitecture?
Cell size, spacing or packing density and layers
Was used to divide brain into 52 regions by Korbinian Brodmann in 1909
What are the functions of the frontal lobe?
Cognitive function
Attention
Motor functions
MEmory
Language
What are the functions of the parietal lobe?
Sensation
Sensory aspect of language
Spatial orientation and self perception
What is the function of the occipital lobe?
Processing visual information
What is the function of the temporal lobe?
Processing auditory information, emotions and memory
What does the limbic lobe include?
amygdala, hippocampus, mamillary body, and cingulate gyrus
What is the limbic lobe concerned with?
learning, memory, emotion, motivation and reward
What is the grey matter composed of ?
neuronal cell bodies and glial cells
What is the insular cortex?
Lied deep withon the lateral fissure
Concerned with visceral sensation, autonomic control, interoception, auditory processing, visual-vestibular integration
What is the internal structure of the white matter?
Myelinated neuronal axons arranged in tract
What connects cortical areas?
White matter tracts
What are association fibres?
connect areas within the same hemisphere
What are commissural fibres?
Connect homologous structure in left and right hemispheres
What are projection fibres?
connect cortex with lower brain structures (e.g. thalamus, brain stem and spinal cord)
What is the name of the fibres which connect the frontal and occipital lobes?
Superior Longitudinal Fasciculus
What is the name of the association fibres which connect the frontal and temporal lobes?
Arcuate Fascicules
Uncinate fascicules (connects anterior frontal and temporal)
What si the name of the association fibre which connects the temporal and occipital lobe?
Inferior Longitudinal Fasciculus
What are the two main sets of commissural fibres?
Corpus callosum and anterior commissure
what is the difference between afferent and efferent projection fibres?
Afferent is towards the cortex while efferent is away from the cortex
What is the corona radiata?
what the projection fibres radiate together as
Where do the projection fibres converge?
Through an internal capsule between the thalamus and basal ganglia
What effects will lesions in the primary cortices have compared to the secondary / association cortices?
Function predictable / less
Organised topographically / not
Symmetry between left and right / weak symmetry
What is the role of the primary motor cortex?
controls fine, discrete, precise voluntary movements.
Provides descending signals to execute movements.
What is the role of the supplementary motor cortex?
Involved in planning complex movements (e.g. internally cued)
What is the role of the premotor area?
Involved in planning externally cued movements
What is the role of the primary somatosensory cortex?
processes somatic sensations arising from receptors in the body (e.g. fine touch, vibration, two-point discrimination, proprioception, pain and temperature.
Which lobe of the brain is the somatosensory cortex in?
Parietal lobe
What is the role of the somatosensory association lobe?
Interpret significance of sensory information
Awareness of self and awareness of personal space
What is the role of the primary visual cortex?
Processes visual stimuli
What is the role of the visual association cortex?
Gives meaning and interpretation of visual input
What is the role of the primary auditory cortex?
processes auditory stimuli
What is the role of the auditory association cortex?
Gives meaning and interpretation of auditory input
What is Broca’s area?
Production of language
What is Wernicke’s area?
Involved in the understanding of language
What is the role of the pre-frontal cortex?
Attention
Adjusting social behaviour
Planning
Personality expression
Decision Making
What changes occur due to frontal lobe lesions?
Changes in personality and inappropriate behaviour
What is meant by contralateral neglect?
When there is a lesion to the cortex on one side of the brain in the parietal lobe leading to complete disregard of what the other side of the body is doing, and lack of self awareness
What do temporal lobe lesions lead to ?
Agnosia - the inability to recognise
Anterograde amnesia- the inability to form new memories
What does a lesion to Broca’s Area lead to?
Inability to produce speech, however comprehension is intact - expressive aphasia
What does a lesion to Wernicke’s Area lead to?
Receptive aphasia - able to produce speech however comprehension of speech is significantly impaired
Which commisural fibres connect Broca’s and Wernicke’s Areas?
Arcuate fasciculus
What is prosopagnosia?
Inability to recognise familiar faces or learn new faces
What does a lesion in the primary visual cortex lead to?
blindness in the corresponding part of the visual field
What happens after a lesion to the visual association cortex?
Deficits in interpretation of visual information e.g prosopagnosia
How can PET scans be used to assess brain function?
blood flow directly to a brain region
How can Functional magnetic resonance imaging (fMRI)
be used to measure cortical function?
amount of blood oxygen in a brain region
What does Electroencephalography (EEG) do?
Measures electrical signals produced by the brain
What does Magnetoencephalography – (MEG) do?
Measures magnetic signals produced by the brain
What are Somatosensory evoked potentials?
series of waves that reflect sequential activation of neural structures along the somatosensory pathways
How does transcranial magnetic stimulation work?
Assesses the functional integrity of neural circuits
Uses electromagnetic induction to stimulate neurons
What is the purpose of brain stimulation?
Investigate neural interactions controlling movement following spinal cord injury
Investigate whether a specific brain area is responsible for a function?
What is Transcranial direct current stimulation (tDCS)?
Uses low direct current over the scalp to increase or decrease neuronal firing rates
What is Diffusion tensor imaging (DTI)?
Imaging used to assess the structure of the brain Based on diffusionof water molecules
What is DTI with tractography?
3D reconstruction to assess neural tracts
Lesions to which brain area are common following a stroke?
Wernicke’s
What are three ways that cortical function is assessed?
Imaging
Encephalography
Brain stimulation
What does fMRI detect changes in?
Changes in blood oxygenation and flow which occur in response to neural activity
What it the routine investigation for people with spinal cord injury to confirm where along the pathway lesion is?
EEG
Where is the activity recorded to and from in an EEG?
Recorded along the path of an impulse from the peripheral nerve up to the brain
A 62 year old woman comes into hospital for a check-up. She says: Yes…ah..Monday…er…me…er…hospital…and…doctor. Where might she have a lesion?
Broca’s = Expressive Aphasia = Left Frontal Lobe lesion
