Lecture 12: Cerebrum Flashcards
Where is cortical information housed?
In the gyri
Why are the gyri important?
Because they are where cortical information is housed
What is in the outer part of gray matter?
Cortical neuronal cell bodies extending axons to different places
Where can cortical neurons extent their axons?
*From one gyrus to another
*One lobe to another
*To the other hemisphere
*Down to the spinal cord
Where do short association fibers go?
From one gyrus to another gyrus in the the same lobe (or a gyrus close by)
Where do long association fibers go?
From one lobe to another lobe and stay on the same side of the cortex
Where do commissural fibers go?
From one hemisphere to the other (through the corpus callosum)
Where do Projection fibers go?
Down the spinal cord
What are the for types of association fibers?
*Short association fibers
*Long association fibers
*Commissural fibers
*Projection fibers
What association fibres go from gyrus to gyrus?
Short association fibers
What association fibres go from lobe to lobe?
Long association fibers
What association fibres go from hemisphere to hemisphere?
Commissural fibers
What association fibres go down the spinal cord?
Projection fibres
What are the main projection fibers that go down the spinal cord?
*Corticospinal
*Corticobulbar
*Spinothalamic
*Dorsal Columns Medial Lemniscal
What is the internal capsule?
The white matter tracts that travel between the thalamus and basal ganglia in the brain
What are the three parts of the internal capsule?
Anterior Limb
Genu
Posterior Limb
What are the parts of the basal ganglia?
*Caudate
*Putamen
*Globus Pallidus
What is in the anterior limb of the Internal Capsule?
Thalamocortical projects (all sensory afferents except for afferents)
What pathways are part of the thalamocortical projects that go through the anterior limb of the internal capsule?
*Spinothalamic tract
*Dorsal Columns Medial Lemniscus
*Trigeminothalamic tract
What pathways are part of the Posterior Limb?
Corticospinal tracts for conscious movements of the lower limbs
What is the Corticobulbar tracts?
Motor tracts for conscious movement of the muscles of the face
What is housed in the genu of the Internal Capsule?
The Corticobulbar tracts
What are the nuclei associated with the corticobulbar tracts?
*Oculomotor nucleus
*Abducens
*Trochlear
*Trigeminal
*Facial
Why is a stroke or lesion the the internal capsule important?
Because the internal capsule houses many axon tracts
What is found in layer I of the cortex?
- Few nerve cell bodies
- Many dendritic and axonal processes in synaptic interaction
What is found in layer II of the cortex?
- Small neurons which establish intracortical connections
What is found in layer III of the cortex?
- Medium-sized neurons giving rise to association and commissural fibres
What is found in layer IV of the cortex?
Termination of afferent fibres from the thalamus
What is found in layer V of the cortex?
- The origin of projection fibres to extracortical targets, such as BG, thalamus, brainstem and spinal cord
- In the primary motor cortex of the frontal lobe, this layer contains corticospinal tract cell bodies
What is found in layer VI of the cortex?
Association and projection fibers
In what layer of the cortex is association and projection fibers found?
Layer VI
In what layer of the cortex are:
- Few nerve cell bodies
- Many dendritic and axonal processes in synaptic interaction
Layer I
In what layer of the cortex are:
- Small neurons which establish intracortical connections
Layer II
In what layer of the cortex are:
- Medium-sized neurons giving rise to association and commissural fibres
Layer III
In what layer of the cortex are:
- Termination of afferent fibres from the thalamus
Layer IV
In what layer of the cortex are:
- The origin of projection fibres to extracortical targets, such as BG, thalamus, brainstem and spinal cord
- In the primary motor cortex of the frontal lobe, this layer contains corticospinal tract cell bodies
Layer V
What is functionally located in the Frontal Lobe?
- Higher cognitive function
- Motor planning and execution
- Language
What is functionally located in the Parietal Lobe?
- Somatic sense of body image
- 3D localization of self and targets in space
- Language
What is functionally located in the Occipital lobe?
Vision
What is functionally located in the temporal lobe?
- Short-term memory
- Learning
- Auditory
Where is:
- Higher cognitive function
- Motor planning and execution
- Language
Frontal Lobe
Where is:
- Somatic sense of body image
- 3D localization of self and targets in space
- Language
Parietal Lobe
Where is:
- Vision
Occipital lobe
Where is:
- Short-term memory
- Learning
- Auditory
Temporal Lobe
What is stored in the Limbic system?
Emotional, social and sexual behavior
Where is:
Emotional, social and sexual behavior
Limbic system
What is information on functional localization mostly from?
- Stimulation and ablation studies
- Electrophysiological recording
- Observations of regional blood flow
- Post mortem studies of patients with known lesions
What is the Montreal surgery?
Stimulating the brain with electrical probes while patients were conscious to observe their responses. This led to the cortical homunculus
What led to homunculus?
The Montreal surgery where they stimulated brains of conscious people and observed responses
What led to Broca’s area?
The post-mortem study of patient ‘Tan’ who could understand everything but could only speak the word Tan
What was discovered in patient Tan?
A lesion in the left inferior frontal lobe - the orbital triangular and opercular which makes up Broca’s speech area
What area of the brain is Broca’s speech area?
Left inferior frontal lobe - the orbital triangular and opercular
Where is Wernicke’s area?
The posterior portion of the left temporal lobe
What happens if there is a lesion in Wernicke’s area?
People cannot understand what is being said to them and their speech is often incoherent and makes no sense**
What is the function of the Primary Auditory Cortex?
Sound Localization
Where is the primary auditory cortex located?
Heschl’s gyrus
What is housed in Heschl’s gyrus?
The primary auditory cortex
Where is information carry from Heschl’s gyrus?
Short association fibres carry information to neighbouring gyri like Wernicke’s area and Broca’s area
What is the function of Wernicke’s sensory speech area?
Comprehension of sound
What will a lesion to Wernicke’s sensory speech area cause?
Sensory and Receptive Aphasia
What is Sensory Aphasia?
Inability to understand spoken word
What is receptive aphasia?
When someone is able to speak well and use long sentences, but what they say may not make sense
What may cause sensory and receptive aphasia?
A lesion to Wernicke’s sensory speech area