Cortical Organisation and Function Flashcards
What are the structures of the columns in the cerebral cortex?
- Small pyramidal neuron
- Granule (sellate) neuron
- Large pyramidal neuron
What is cytoarchitecture?
Arrangement of cells by size, spacing, packing, density and layers
What is the role of the frontal lobe?
- Regulating and initiating motor function
- Language
- Cognitive functions (executive)
- Attention
- Memory
What is the role of the parietal lobe?
- Sensation (touch and pain)
- Sensory aspects of language
- Spatial orientation
- Self-perception
What is the role of the occipital lobe?
Processing visual information
What is the role of the temporal lobe?
- Auditory processing
- Emotions
- Memories
- Language
What structures are included in the limbic lobe?
- Amygdala
- Hippocampus
- Mammillary body
- Cingulate Gyrus
What is the role(s) of the limbic lobe?
- Learning
- Emotion
- Memory
- Motivation
- Reward
(LEMMR)
Where is the insular cortex?
Deep within the lateral fissure
What is the insular cortex involved in?
- Visceral sensations
- Autonomic control
- Auditory processing
- Visual-vestibular integration
- Interoception
(VAAVI)
What is grey matter comprised of?
- Neuronal cell bodies
- Gilal cells
(85 million each)
What is white matter comprised of?
Myelinated neuronal axons (arranged in tracts)
What do white matter tracts do?
Connect cortical areas
What are association fibres?
White matter tracts that connects areas in the same hemisphere
What are commissural fibres?
White matter that connects homologous structures in the left and right hemispheres.
What are projection fibres?
White matter that connects the cortex with lower brain structures (thalamus, brainstem and spinal cord)
What are the 4 main association fibres?
- short ‘u’ fibres
- Superior Longitudinal Fasciculus
- Arcuate Fasciculus
- Inferior Longitudinal Fasciculus
- Uncinate Fasciculus
What does the superior longitudinal fasciculus connect?
The frontal and occipital lobes
What does the arcuate fasciculus connect?
The frontal and temporal lobes
What does the inferior longitudinal fasciculus connect?
The temporal and occipital lobes.
What does the uncinate fasciculus connect?
The anterior frontal and temporal lobes
What are the 2 main commissural fibres?
- Corpus callosum
- Anterior commissure
What are the 2 different directions of projection fibres?
- Afferent (towards the cortex)
- Efferent (away from the cortex)
What is the corona radiata?
- Projection fibres deeper to the cortex
- converge through the internal capsule between the thalamus and the basal ganglia.
Characteristics of the primary cortices?
- Predictable function
- Topographical organisation
- Symmetrical
Characteristics of the secondary/association cortices?
- less predictable function
- not organised topographically
- weak or absent symmetry
What is the role of the primary motor cortex of the frontal lobe?
- Fine, discrete, precise and voluntary movements
- descending signals for movement
What is the role of the supplementary motor area of the frontal lobe?
Planning complex movements
(internally cued)
learnt movements
What is the role of the premotor area of the frontal lobe?
Planning externally cued movements
What is the role of the primary somatosensory area of the parietal lobe?
Processes somatic sensations from the rest of the body:
- Fine touch
- Vibration
- Two-point discrimination
- Proprioception
- Pain
- Temperature
What is the role of the somatosensory association of the parietal lobe?
- Interprets the significance of the sensory information
- Awareness of self and awareness of personal space
What is the role of the primary visual area of the occipital lobe?
Processing visual stimuli
What is the role of the visual association of the occipital lobe?
Provides meaning and interpretation of the visual input.
What is the role of the primary auditory region of the temporal lobe?
Processes auditory stimuli
What is the role of the auditory association in the temporal lobe?
Gives meaning and interprets the auditory input
What is the role of the prefrontal cortex?
- Attention
- Social behaviour
- Planning
- Personality expression
- Decision making
What is the role of Broca’s area?
Production of language
What is the role of Wernicke’s area?
The understanding of language
What is the effect of frontal lobe lesions?
- Changes in personality
- Inappropriate behaviour
What is the effect of parietal lobe lesions?
- Contralateral neglect
- Lack of awareness of self (opposite side to site of the lesion)
- Lack of awareness of extrapersonal space
(opposite side to site of the lesion)
What is the effect of temporal lobe lesions?
- Agnosia (unable to recognise)
- Anterograde amnesia (unable to form new memories)
What is the effect of a lesion to Broca’s area?
Expressive aphasia (poor production of speech, comprehension intact)
What is the effect of a lesion to Wernicke’s area?
- Receptive aphasia
- poor comprehension of speech, production is fine
What is the effect of lesions to the primary visual cortex of the occipital lobe?
Blindness in the corresponding region of the visual field (opposite side of lesion).
What effect does a lesion to the visual association cortex of the occipital lobe have?
Deficits in interpretation of visual information
- prosopagnosia: unable to recognise or learn faces
- agnosia (inability to recognise colour)
What are the 2 forms of imaging cortical function?
- PET (positron emission tomography)
- fMRI (functional magnetic resonance imaging)
What does a PET scan indicate?
The blood flow into the region
What does the fMRI scan show?
The blood oxygen levels in the brain region.
What are the 2 forms of encephalography used to assess cortical function?
- EEG (electroencephalography)
- MEG
(magentoencephalography)
What does a EEG measure?
The electrical signals produced by the brain
What does a MEG measure?
The magnetic signals produced by the brain
How does the EEG assess the cortical function?
- Visual evoked potentials
- Event-related potentials/evoked potentials
What is a DTI?
- Diffusion tensor imaging
- based on the diffusion of water molecules
What is a DTI with tractography
A 3D reconstruction used to assess the neural tracts.
What does tDCS (transcranial direct current stimulation) involve?
Using a low direct current over the scalp to increase or decrease neuronal firing rates
What has tDCS been proven as a promising treatment for?
- Drug-resistant epilepsy
- Depression
What does TMS (transcranial magnetic stimulation) involve?
Using electromagnetic induction to stimulate neurons
What does TMS assess?
The functional integrity of neural circuts
What has TMS been seen as a promising treatment of?
- Migraines
- Depression
- Tinnitus
- Epilepsy
What can TMS be used to investigate?
- Neural interactions controlling movement following spinal cord lesions
- The responsibility of different parts of the brain
What is the cerebral cortex?
- covers the entire surface of the brain
- together with deep nuclei, contains grey matter
- highly folded with gyri and sulci
- organised into lobes
What sulcus separates the frontal and parietal lobe?
the central sulcus
What seperates the parietal and occipital lobe?
parieto-occipital sulcus
What seperates the temporal lobe from the parietal and frontal lobe?
lateral fissure
What fissure separates the 2 hemispheres?
deep longitudinal fissure
What happens if you have a lesion on the right parietal lobe?
- left contralateral neglect
- lack of self-awareness and spatial awareness
What is neglect?
- lack of awareness of sensory information in the visual field
- result of parietal lobe damage
What is agnosia?
the inability to recognise objects
Where is Broca’s area?
in the frontal lobe
When are EEGs used?
in the diagnosis of epilepsy and sleep disorders
How does an EEG of somatosensory evoked potentials work?
- stimulation given to the median nerve
- series of waves that reflect sequential activation of neural structures along the somatosensory pathways
