N8- Cerebral cortex and thalamus Flashcards
What is the role of cerebral cortex?
regional specialisation of function
what is the role of the thalamus?
relay and integration en-route to cortex
what is the basic cytoarchitecture of the cerebral cortex?
consists of neuronal cell bodies, axons and dendrites, arranged in layers (along with supporting glial cells)
what are the 2 basic types of the cortex?
- allocortex
- neocortex
Describe allocortex.
evolutionarily older and is only found in a small part of the brain
Describe the neocortex.
consists of 6 layers of cells, although the layers are more obvious in some areas than others
What are the 6 layers of the neocortex?
1- molecular layer 2- external granular layer 3- external pyramidal cell layer 4-internal granular layer 5-ganglionic layer (internal pyramidal cells) 6- multiform (polymorphic) cel layer
Describe the molecular layer.
Few cells. Mostly horizontally arranged axons and dendrites of afferents, intercortical neurons and apical dendrites of pyramidal cells
why is the molecular layer named?
The many processes make It look punctuate
what are the input layers of the neocortex?
- external granular layer (local)
- internal granular layer (thalamus)
What are the two output layers of the neocortex?
- external pyramidal layer (local)
- ganglionic layer (internal pyramidal cells) (BS/spinal cord)
what are the 2 classes of the cerebral cortex?
- Primary cortex
- Association cortex
Describe the primary cortex.
Exit (motor) and entry points (sensory)
Describe the association cortex.
integration, complex
processing adjacent to primary (takes information and analyses it from the primary cortex)
Describe the Brodmann’s areas.
Brodmann’s map divides the cortex into numbered areas based on subtle differences in the cytoarchitecture of the cortex
What does the cytoarchitecture of each area in the brodmanns map link to?
Specific function
What Brodmanns area is the primary visual cortex found>
17
where does the primary motor area sit?
in pre central gyrus
what does the primary motor area control?
More direct control of motor activity than other motor areas - force, direction and speed of muscle contraction
what activates the primary motor cortex?
simple movement
What is involved in planning complex tasks?
supplementary motor area
Describe carrying out a complex movement.
Carry out a complex movement, both the primary and supplementary motor areas are activated
How is the supplementary motor area activated alone?
Just rehearse in your mind carrying out a complex movement
What is the role of the premotor cortex?
Preparation for action - posture and gait
integration of spatial information and planned movement
In the post central gyrus, , how are different body regions represented in the primary somatosensory cortex?
represented as a body map -somatotopic
where is the association somatosensory cortex found?
superior parietal lobule
what is the role of the association somatosensory cortex?
Awareness/perception in space
what does damage to the pre-frontal region of the association cortex lead to?
disorders of personality and motivation
what are 5 features of frontal lobe damage?
1) Personality changes
(2) Deficits in planning
(3) Perseveration
(4) Primitive reflexes (suckling reflex)
(5) Abulia (lack of motivation; slowness of decision making)
Where are language areas of the cerebral hemispheres found?
In about 95% of right handed people and about 65% of left handed people, language is centred in the left hemisphere
What area programs to make speech?
Broca’s area
What is caused by a lesion In broca’s area?
Expressive aphasia
-language is reduced to disjointed words and sentence construction is poor but comprehension is OK
What area programs to understand/ comprehend speech?
Wernicke’s area
What is caused by a lesion in Wernicke’s area?
Receptive aphasia
-unable to understand/generate meaningful language
where does Wernicke’s area sit in relation to the primary auditory area?
Posterior and inferior
What is processed in the left hemisphere?
- Language
- Calculation
What is processed in the right hemisphere?
- Drawing
- Music
- Spatial perception
In the feel the keys experiment, what happens if the corpus callous is severed?
Left hand feels, right cortex recognises, but cannot activate the language centres in the left hemisphere to speak the word keys
what is the thalamus made of?
collection of nuclei (grey matter)
What is the function of the thalamus?
Relays and processes sensory and motor information en-route
to cortex
What is the role of each. nucleus in the thalamus?
Each nucleus communicates (projects) to the cortex with related function
what sits between the two sides of the thalamus?
3rd Ventricle
What separates the putamen and thalamus?
Internal capsule
What is the largest nuclei in the thalamus and when is it activated?
- Pulvinar
- activated when looking at something
What nucleus communicates sensory information from the body to the cortex?
Ventroposteriolateral (VPL)
What nucleus communicates sensory information from the head to the cortex?
Ventroposteriomedial (VPM)
What is involved In communication with the primary visual cortex?
lateral geniculate body (input from optic nerves)
What is involved In communication with the auditory cortex?
medial geniculate body (input from auditory system)
With connections with the motor cortex, what provides motor feedback?
Basal ganglia and cerebellum
what nucleus receives input from cerebellum?
Ventro lateral
What nucleus receives input from basal ganglia?
Ventro anterior
What is the anterior nucleus’s function and what does it connect to?
Memory/instinctive behaviour
-connects with limbic system
What is the intralaminar nucleus function and where does it receive input from?
Pain/arousal
-receive input from reticular system, pain pathways and project diffusely to cortex
What is the function of the cortex?
regional specialisation of function
What is the function of the thalamus?
relay and integration en-route to cortex
