Cortical organisation and function Flashcards
where is the cerebral cortex?
What does it consist of?
covers entire surface of the brain
contains grey matter (along with deep nuclei)
What do foldings in the cortex create?
Gyri and sulci
what do fissures separate?
hemispheres and lobes
What is the microscopic organisation of the brain?
Organised into layers and columns
what are Brodmann maps
52 regions based cytoarchitecture (cell size, spacing/ packing density and layers)
how are Brodmann maps useful?
areas relate to function e.g primary somatosensory (1,2,3), primary motor (4)
What seperates the primary motor and primary somatosensory cortices?
Central sulcus
what are the different cerebral cortex lobes
Frontal
Parietal
Temporal
Occipital
what are the functions of the Frontal lobe iM CALM
Regulating and initiating Motor function
Cognitive function (executive function e.g. planning)
Attention
Language
Memory
what are the functions of the parietal lobe?
sensation - touch/pain
sensory aspects of language
spatial orientation and self-perception
what are the functions of the occipital lobe?
processing visual information
what are the functions of the temporal lobe
processing auditory information
emotions
memories
what is contained in the limbic lobe?
amygdala, hippocampus, mamillary body, cingulate gyrus
what are the functions of the limbic lobe? MEMs and LeaRning
MEMs and LeaRning
memory
emotion
motivation
learning
reward
where is the insular lobe?
lies deep into lateral fissure
Functions of insular lobe
Concerned with visceral sensations (e.g. thirst, hunger, changed internal temp), autonomic control, and interoception, auditory processing, visual-vestibular integration
what is grey matter?
neuronal cell bodies and glial cells
what is white matter?
myelinated neuronal axons arranged in tracts
what are the types of white matter tracts?
association fibres, commissural fibres, projection fibres
what are association fibres?
connect areas in same hemisphere
Types of assocation fibres
Short fibres
Long fibres
what are commissural fibres?
Examples
connect homologous structures in left and right hemispheres
e.g corpus callosum, anterior commissure
what are projection fibres
connect cortex with lower brain structures (e.g. thalamus, brain stem and spinal cord)
what association fibres connect the frontal and occipital lobe?
superior longitudinal fasciculus
what association fibres connnect the frontal and temporal lobes, specifically Brocas and Wernickes area?
arcuate fasciculus
what association fibres connect the temporal and occipital lobes?
Inferior longitudinal fasciculus
what association fibres connect the anterior frontal and temporal lobes?
Uncinate fasciculus
Difference between afferent and efferent projection fibres
Afferent – towards cortex
Efferent – away from cortex
where do projection fibres radiate and converge?
Deeper to cortex radiate as the corona radiata
Converge through the internal capsule (between the thalamus and basal ganglia)
Difference between primary and secondary/ association cortices
primary- function predictable,organised topographically, symmetry between left and right
secondary- function less predicatble, not organsied topogrphically, left-right symmetry weak or absent
what are the motor areas of the frontal lobe?
primary
supplementary
premotor
what does the primary motor area of the frontal lobe control?
controls fine, discrete, precise voluntary movements.
Provides descending signals to execute movements.
what does the supplementary motor area of the frontal lobe control?
planning complex movements, internally cued
what does the premotor area of the frontal lobe control?
planning movements, externally cued
what area of the frontal lobe controls fine, discrete voluntary movements?
primary motor area
what area of the frontal lobe plans complex, internally cued movements?
supplementary motor area
what area of the frontal lobe plans movements that are externally cued?
premotor area
what areas are contained in the parietal lobe?
primary somatosensory area
somatosensory association area
what is controlled by the primary somatosensory area?
processes somatic sensations arising from receptors in the body (e.g. fine touch, vibration, two-point discrimination, proprioception, pain and temperature.)
what is controlled by the somatosensory association area of the parietal lobe?
Interpret significance of sensory information, e.g. recognizing an object placed in the hand.
Awareness of self and awareness of personal space
what is controlled by the primary visual area of the occipital lobe?
processes visual stimuli
what is controlled by the visual association area of the occipital lobe?
gives meaning and interpretation of visual input
what is controlled by the primary auditory area of the temporal lobe?
processes auditory stimuli
what is controlled by the auditory association area of the temporal lobe?
gives meaning and interpretation of auditory input
what is the prefrontal cortex responsible for? APPSD
attention
planning
personality expression
adjusting social behaviour
decision making
what is the brocas area responsible for?
motor aspect of speech, production of language
where is the Brocas area?
left frontal lobe, just above sylvian fissure
what is Wernicke’s area responsible for?
understanding and comprehension of language
where is Wernicke’s area found?
left temporal lobe, superiorly and caudally
what is the result of a frontal lobe lesion?
changes in personality, inappropriate behaviour
what is the result of a parietal lobe lesion?
contralateral neglect
lack of awareness of self on opposite side
lack of awareness of opposite side of extrapersonal space
what is the result of a temporal lesion?
agnosia (inability to recognise)
possible anterograde amnesia- inability to form new memories
what is Brocas aphasia?
expressive aphasia - poor production of speech, comprehension intact
what is Wernicke’s aphasia?
receptive aphasia - poor comprehension of language, production is fine
what would a lesion to the primary visual cortex of the occipital lobe cause?
blindness in the corresponding part of the visual field
what would a lesion to the visual association area of the occipital lobe cause?
deficits in interpretation of visual information e.g prosopagnosia: inability to recognise familiar faces or learn new faces (face blindness)
what are the 4 main methods of assessing cortical function?
Positron emission tomography (PET)
functional magnetic resonance imaging (fMRI)
electroencephalography (EEG)
magnetoencephalography (MEG)
what is a PET scan?
demonstrates the blood flow directly to a brain region
what is an fMRI scan?
demonstrates amount of blood oxygen in brain regions
what is an EEG?
measures electrical signals produced by the brain
what is an MEG?
measures magnetic signals produced by the brsin
what are visual evoked potentials?
type of encephalography
stimulates visual sensations
what are somatosensory evoked potentials?
series of waves that reflect sequential activation of neural structures along the somatosensory pathways
what is transcranial magnetic stimulation?
How is this useful clinically
assesses functional integrity of neural circuits, using electromagnetic induction to stimulate neurones
used to
1.investigate neural interactions controlling movement following spinal cord injury
2. Investigate whether a specific brain area is responsible for a function, e.g. speech
what is transcranial direct current stimulation
uses low direct current over the scalp to increase or decrease neuronal firing rates
What imaging is used to assess brain structure
DTI
DTI with tractography
what is diffusion tensor imaging?
scan based on the diffusion of water molecules
what is diffusion tensor imaging with tractography?
3D reconstruction of brain to assess neural tracts
