Cerebral Cortex Flashcards
What is the nature of the structure of the cortex?
Organized into layers & columns
How are different regions of the cortex characterized?
Cytoarchitecture - based on type of cells, spacing, density, layers.
52 regions identified by Brodmann
Areas relate to function
What is the function of the frontal lobe?
Regulating & initiating motor function
language
cognitive function - executive function (planning)
attention memory
What is the function of the parietal lobe?
Sensation - touch, pain.
Sensory aspects of language
spacial orientation, self perception
What is the main function of the Occipital lobe
Processing visual information
What are the functions of the Temporal lobe?
Processing auditory information
emotions, memories
What is the function of the Limbic lobe?
Contains; amygdala, hippocampus, mammillary body, cingulate gyrus.
Concerned with learning, memory, emotion, motivation & reward.
What is the function of the Insular Cortex?
Lies deep within the lateral fissure
Concerned with visceral sensations, autonomic control, interception, auditory processing, visual vestibular integration.
What is the structure of the brain?
Grey matter - neuronal cell bodies & glial cells- 85 billion each.
White matter - Myelinated neuronal axons arranged in tracts.
What connects cortical areas together?
white matter tracts
Which white matter tracts connect areas within the same hemisphere?
Association fibres
Which white matter tracks connect homologous structures in the left & right hemisphere?
Commissural fibres
Which white matter tracts connect cortex with lower brain structures (thalamus, brain stem)?
Projection fibres
Which Association fibre connects the frontal and occipital lobes?
Superior Longitudinal Fasciculus
Which Association fibre connects the frontal and temporal lobes?
Arcuate Fasciculus
Which Association fibre connects the temporal and occipital lobe?
Inferior Longitudinal Fasciculus
Which Association fibres connect the frontal and temporal lobes?
Uncinate Fasciculus
What are some examples of commissure fibres?
Corpus callosum - disconnected in severe epilepsy surgically
Anterior commissure
Where do projection fibres radiate deeper to the cortex?
Corona radiata
Where do projection fibres converge through?
Internal capsule between thalamus & basal ganglia
What are the features of primary cortices?
Predictable function
Organized topographically
Symmetry between left & right
What are the features of secondary cortices?
Less predictable function
not organize dtopographically
left-right symmetry is weak/absent
What are the motor areas of the Frontal lobe?
Primary motor cortex
Supplementary area
Premotor area
What is the function of the Primary motor cortex?
Controls fine, discrete, pre-voluntary movement.
Provides descending signals to execute movements.
What is the function of the Supplementary area?
Involved in planning complex movements e.g. internally cued - production of speech
What is the function of the Premotor area?
Planning externally cued movements - seeing an object and wanting to pick it up
What is the function of the primary somatosensory area of the parietal lobe?
Processes somatic sensations arising from receptors in the body (e.g. fine touch, vibration, two-point discrimination, proprioception, pain and temperature.
What is the function of the Somatosensory association centre in the Parietal lobe?
Interpret the significance of sensory information, e.g. recognizing an object placed in the hand.
Awareness of self and awareness of personal space
What are the main cortices of the Occipital lobe?
Primary visual - process visual stimuli
Visual association - Gives meaning & interpretation of visual input
What are the main Cortices of the temporal lobe?
Primary auditory - process auditory stimuli
Auditory association - Gives meaning & interpretation of auditory input
What is meant by Tonographic?
Different frequencies of sound are mapped onto different areas of the auditory cortex.
What is Broca’s area associated with?
Speech production
What is Wernicke’s area associated with?
Understanding of language
What is the Prefrontal cortex associated with?
Attention adjusting social behaviour planning personality expression decision-making
What happens if you have Frontal lobe lesions?
Changes in personality
Inappropriate behaviour
What would happen following a Parietal lobe lesion?
Lesion in the right hemisphere would cause neglect on the left side of the body. Contralateral neglect
What would happen following a temporal lobe lesion?
Leads to agnosia, inability to recognise.
What would a lesion in Broca’s are lead to?
expressive aphasia - poor production of speech, comprehension intact.
What would happen following a lesion in Wernicke’s area?
Receptive aphasia - poor comprehension of speech, production is fine.
What would a primary motor cortex lesion present as?
Blindness in the corresponding part of the visual field
What would a lesion in the Visual association area of the occipital lobe?
Defects in interpretation of visual information. e.g. prosopagnosia - inability to recognise familiar faces/ learn new faces.
How do we assess cortical function?
Positron emission tomography PET - bllod flow to a brain region (glucose consumption).
Functional magnetic resonance imaging fMRI - amount of blood oxygen in a brain region.
Electroencephalography EEG - Measures electrical signals produced by the brain.
Magneto encephalography MEG - 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.
What happens in Transcranial direct current stimulation, tDCS?
Uses low direct current over the scalp to increase/decrease neuronal firing rates.
How can we image neuronal tracts in the brain?
Diffusion tensor imaging DTI - based on diffusion of water molecules.
