Cerebral Cortex Flashcards
What are included in the grey matter?
Deep nuclei
How is the cerebral cortex organised superficially?
Highly folded surface with gyri and sulci (indentations)
What are the 6 microscopic layers of the cerebral cortex?
1) Molecular layer
2) External granular layer
3) External pyramidal layer
4) Internal granular layer
5) Internal pyramidal layer
6) Multiform layer
What are the total number of cytoarchitecture classifications are there?
52
Which cytoarchitecture regions are associated with the primary somatosensory cortex?
1,2,3
Which cytoarchitecture region is associated with the primary motor cortex?
4
What are the four cerebral lobes?
Occipital,
Parietal
Temporal
Frontal lobes
What is the function of the frontal lobe?
Associated with regulating and initiating motor function (Primary motor cortex)
- Language (Broca’s area)
- Cognitive (executive, including planning and problem solving)
- Attention and memory
What is the function of the parietal lobe?
Includes the primary somatosensory cortex responsible for processing somatic sensations.
• Touch, pain, temperature, proprioception, fine touch and vibration
• Sensory aspects of language
• Spatial orientation and self-perception.
What is the function of the temporal lobe?
Processes auditory information including the primary auditory cortex, and Wernicke’s area (Comprehension and understanding of speech).
• Emotions
• Memory
What is the function of the occipital lobe?
Processes visual information, including the:
• Primary visual cortex and visual association area
What four structures are connected within the limbic system?
- Amygdala
- Hippocampus
- Mamillary body
- Cingulate gyrus
Where is the insular cortex?
Resides deep within the lateral fissure
What five functions are concerned with the insular cortex?
- Visceral sensations
- Autonomic control
- Interocepetion
- Auditory processing
- Visual-vestibular integration (Input from balance organs).
What do the grey matter structures represent?
Includes neuronal cell bodies and glial cells
What do the white matter structures represent?
Myelinated neuronal axons arranged in tracts (resides deep)
What are the three white matter tracts?
Association fibres
Comnissural fibres
Projection fibres
What are the association fibres?
Connect areas within the same hemisphere
What are the commissural fibres?
Connect homologous structure in left and right hemisphere
What are the projection fibrs?
Connect cortex within lower brain structure (Thalamus, brainstem and spinal cord)
What are the two types of association fibres?
Comprise of both short (U-fibres) and long fibres
What are the four association fibres?
- Superior longitudinal fasciculus connects the frontal and occipital lobes.
- Arcuate fasciculus connects the frontal and temporal lobes
- Inferior longitudinal fasciculus connects temporal and occipital lobes
- Uncinate fasciculus connects the anterior frontal lobe and temporal lobes
What does the superior longitudinal fasciculus connect?
The frontal and occipital lobe
What does the arcuate fasciculus connect?
The frontal and temporal lobe
What does the inferior longitudinal fasciculus connect?
The temporal and occipital lobes
What does the uncinate fasciculus connect?
The anterior frontal lobe and temporal lobes
What are the two commissural fibres?
Corpus callosum
Anterior commissure
What are the afferent projection fibres?
Fibres that project towards the cortex
What are the efferent projection fibres?
Fibres that project away from the cortex
Where do the projection fibres radiate as?
Deeper to the cortex radiate as the corona radiata
Where does the corona radiata converge through?
The internal capsule
Where is the internal capsule?
Resides between the thalamus and basal ganglia
What are the differences between primary cortices and secondary/association cortices?
Function predictable/ less predictable
Organised topographically
Where does the primary motor cortex reside?
Within the pre-central gyrus
What does the primary motor cortex control?
Controls fine, discrete, precise voluntary movements
What motor functions are associated with the supplementary area?
Involved in planning movements (externally cued); orchestrating the series of events prior to the movements taking placed –> Plan to move a limb.
What motor functions are concerned with the premotor area?
Involved in planning complex movements (internally cued), plan to coordinate fibres to generate speech.
What is the function of the primary somatosensory cortex?
Processes somatic sensations arising from receptors in the body (fine touch, vibration, two-point discrimination, proprioception, pain and temperature).
Where does the primary somatosensory cortex reside?
Post-central gyrus
What is the function of the somatosensory association cortex?
Interpret significance of sensory information e.g. recognising an object placed in the hand
Awareness of self and awareness of personal space
What are the two regions associated with the occipital lobe?
Primary visual cortex
Visual association area
What is the function of the primary visual cortex?
Receives visual input from the optic nerve via the optic radiations
What is the visual association area?
Gives meaning and interpretation of visual input
What is the function of the primary auditory cortex?
Processes auditory stimuli
Tonographically arranged to specific frequencies
What is the function of the auditory association area?
Gives meaning and interpretation of auditory input
What is the function of the prefrontal cortex?
Concerned with attention, adjusting social behaviour, planning, personality expression and decision making
What is the function of the Broca’s area?
Resides within the left cerebral hemisphere in the frontal lobe
Responsible for the production of language (Associated with motor regions)
What is the function of Wernicke’s area?
Resides within the left temporal lobe
Associated with comprehension and understanding of language
What are the symptoms of a frontal lobe lesion?
Changes in personality and inappropriate behaviour
What are the symptoms of a parietal lobe lesion?
- Contralateral neglect (Hemispatial)
- Lack of awareness of self on left side
- Lack of awareness of left side of extra-personal space.
What are the clinical manifestations with temporal lobe lesions?
Leads to agnosia
Anterograde amnesia
Aphasia
What are anterograde amnesia?
Cannot form new memories
What is the risk implicated in a Bilateral resection of anterior medial temporal lobe structures to cure epilepsy?
Anterograde amnesia
What is the risk of a Broca’s area lesion?
Expressive aphasia - impaired production of speech, comprehension is intact
What is the risk of a Wernicke’s area lesion?
Receptive aphasia- poor comprehension of speech, production of speech is maintained
How are the Wernicke’s and Broca’s area connected?
Via the arcuate fasciculus (from frontal and temporal lobe)
Damage to the primary visual cortex leads to what clinical manifestation?
Blindness in the corresponding part of the visual field
Damage to the visual association area will lead to what clinical manifestation?
Prosopagnosia
What is prosopagnosia?
Inability to recognise familiar faces or learn new faces (face blindness)
What imaging modalities are used in assessing cortical fucntion?
PET and fMRI
What is a PET scan?
Blood flow directly to a brain region associated with a particular active function, using radioactively labelled glucose (fluorodeoxyglucose)
What does a fMRI assess?
This assesses blood oxygenation in a particular brain region (determines the increase in oxygen being delivered to a region of the brain implies increased activity
What is spatial resolution?
Spatial resolution refers to the ability to zoom in onto a specific region and temporal refers to how quickly certain things are changing.
What is an EEG?
Encephalography (EEG)
Measures the electrical signals produced by the brain frequently used in the diagnosis of epilepsy and sleep disorders.
• Event-evoked potentials
Used to ascertain where the signal is blocked
What is MEG?
Measures magnetic signals produced by the brain
What is transcranial magnetic stimulation?
Assesses the functional integrity of neural circuits
Stimulator (magnetic) relies on the production of changing magnetic field which gives rise to electric fields obeying Faraday’s law.
What are the research areas of TMS?
TMS can be used to modulate or downregulate overactive brain regions by interfering with transmission. • Can reduce the onset of epilepsy • TMS in tinnitus patients • Preventative for migraine • Treatment in depressive disorders.
What is tDCS?
Transcranial direct current stimulation (tDCS)
• Uses low direct current over the scalp to increase or decrease neuronal firing rates.
• Power dimes can be used to alter the firing rates of neurones.
Which imaging modality is used to assess structure of the cerebrum?
Diffusion tensor imaging - based on diffusion of water molecules
What is DTI with tractography?
3D reconstruction to assess neural tracts
What is multiple sclerosis?
Multiple sclerosis (MS) is defined as an inflammatory demyelinating disease characterised by episodic neurological dysfunction of the central nervous system (brain and spinal cord). • It is an autoimmune disorder. • Blurred vision, fatigue, difficulty walking, numbness, paraesthesia throughout the body, muscle stiffness and spasms.
Which wave corresponds to a fast motor response?
M (motor) wave
What is the H-reflex?
Induces an indirect response of the motor neurone via a monosynaptic reflex in the spinal cord
What is an F-wave?
A large electrical stimulus can cause activation of the motor axons to conduct antidromically. These action potentials travel along the motor nerve to the spinal cord Cause lower motor neurones in the spinal cord to become activated.
What is an orthodromic wave?
Wave travelling in the normal direction in a nerve fibre
What is an antidromic wave?
Travelling in the opposite direction to that normal in a nerve fibre
What happens when increasing the stimulus intensity to the F wave?
Results in action potential being generated antidromically -> F wave
What is the total motor conduction time (TMCT)?
Total time from primary motor cortex to muscle (MEP latency)
What is the peripheral motor conduction time (PMCT)?
Time from spinal cord to muscle along the motor axon
