Cortical organisation and function Flashcards
What is gyri and sulci?
gyri are the folds/bumps
Sulci are the grooves/pits
How is the cerebral cortex organised?
-Into lobes
-Layers
-Columns
How is the cerebral cortex divided?
-divided into regions known as “brodmann areas”
-Based on cytoarchitecture (cell size, spacing/ packing density and layers)
-Areas shown to relate to function
What are the lobes of the brain?
-Frontal lobe
-Parietal
-Temporal
-Occipital
-Insular cortex
-Limbic
What is the function of the frontal lobe?
-Regulating and initiating motor function
-Language
-cognitive functions (executive function
[e.g. planning])
-attention
-memory
What is the function of the parietal lobe?
Sensation - touch, pain
sensory aspects 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
memories
What is the function of the limbic lobe
Includes the amygdala, hippocampus, mamillary body, and cingulate gyrus
Concerned with learning, memory, emotion, motivation and reward
What is the function of the insular cortex
lies deep within lateral fissure
Concerned with visceral sensations (e.g. hunger/thirst) , autonomic control, and interoception, auditory processing, visual vestibular integration (e.g. motion sickness)
What is the grey matter of the cerebral cortex?
neuronal cell bodies and glial cells – around 85 billion of each
What is the white matter of the cerebral cortex?
Myelinated neuronal axons arranged in tracts
What are the 3 type of fibres that run through the white matter tracts?
- Association fibres (connect areas within the same hemisphere)
- Commissural fibres (Connect homologous structures in left and right hemispheres)
- Projection fibres (connect cortex with lower brain structures (e.g. thalamus, brain stem and spinal cord
What types of association fibres are there? what are their functions?
Short and long fibres:
1.Superior Longitudinal Fasciculus
(connects frontal and occipital lobes)
2.Arcuate Fasciculus -
(connects frontal and temporal lobes)
3.Inferior Longitudinal Fasciculus -
(connects temporal and occipital lobes)
4.Uncinate Fasciculus -
(connects anterior frontal and temporal lobes)
What type of commissural fibres are there?
- Corpus callosum
- Anterior commissure
What are the types of projection fibres?
-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 is the internal capsule
A white matter structure for transmission of information to and from the cerebral cortex
what are the 2 types of cortices/ brodamann areas?
- PRIMARY cortices
Function predictable
Organised topographically
Symmetry between left and right - SECONDARY cortices:
function less predictable
not organised topographically
left-right symmetry weak or absent
What are the cortices of the frontal lobe? What type of information do they process?
Primary:
“primary motor cortex”
controls fine, discrete, precise voluntary movements.
Provides descending signals to execute movements.
Secondary: (there are 2)
1. “Supplementary”
Involved in planning complex movements (e.g.
internally cued)- like speech
2.”Premotor area”
involved in planning movements (e.g. externally cued)
What are the cortices of the parietal lobe? What type of information do they process?
Primary:
“Primary somatosensory cortex”
processes somatic sensations arising from receptors in the body (e.g. fine touch, vibration, two-point discrimination, proprioception, pain and temperature.)
Secondary:
“Somatosensory association”
Interpret significance of sensory information, e.g. recognizing an object placed in the hand. Awareness of self and awareness of personal space
What are the cortices of the occipital lobe? What type of information do they process?
Primary:
“primary visual”
Processes visual stimuli
Secondary:
“Visual association”
Gives meaning and interpretation of visual input
What are the cortices of the temporal lobe? What type of information do they process?
Primary:
“Primary auditory”
processes auditory stimuli
Secondary:
“Auditory association”
Gives meaning and interpretation of auditory input
What are the 3 other brodmann areas? what are they responsible for?
“Prefrontal cortex”
-attention
-adjusting social behavior
-planning
-personality expression
-decision-making
“Broca’s areas”
production of language
“Wernicke’s area”
Understanding of language
What issues would a frontal lobe lesion cause?
-changes in personality
-Inappropriate behaviour
What issues would a parietal lobe lesion cause?
-If lesion in one side/ hemisphere, it would cause issues on the opposite side
e.g. lesion in right hemisphere=
Contralateral neglect (neglect to the left side of body- not shaving the left side of face)
Lack of awareness of self on left side (not a visual defect)
Lack of awareness of left side of extrapersonal space
What issues would a temporal lobe lesion cause?
-agnosia (inability to recognize)
-anterograde amnesia (Inability to form new memories)
What issues would a lesion to the Broca’s area cause?
Expressive aphasia – poor production of speech, comprehension intact
What issues would a lesion to the Wernicke’s area cause?
Receptive aphasia- poor comprehension of speech, production is fine
What issues would a lesion to the Primary visual cortex cause?
blindness in the corresponding part of the visual field
What issues would a lesion to the “visual association” area cause?
deficits in interpretation of visual information e.g. prosopagnosia: inability to recognise familiar faces or learn new faces (face blindness)
What does a PET scan show?
“positron emission tomography”
Blood flow directly to a brain region
-increased blood flow indicative of increased activity in that area
What does an fMRI show?
“Functional magnetic resonance imaging”
Amount of blood oxygen in a brain region
What does an EEG show?
“Electroencephalography”
Measures electrical signals produced by the brain
The action potentials are fired from either:
a) visual stimuli
b) somatosensory activity (e.g. thalamic activity, Mid cervical cord activity
shows a series of waves that reflect sequential activation of neural structures along the somatosensory pathways
What does MEG show?
“Magnetoencephalography”
Measures magnetic signals produced by the brain
What is a TMS?
“Transcranial magnetic stimulation”
Process of:
-using electromagnetic induction to stimulate neurons
-to assess the functional integrity of neural circuits
What is a tDCS?
“transcranial direct current stimulation”
uses low direct current over the scalp to increase or decrease neuronal firing rates
What does a DTI show?
“Diffusion tensor image”
-imaging based on diffusion of water molecules
What does a DTI with tractography show?
-3D reconstruction to assess neural tracts
