Module 33 - Cognition Flashcards
What are the key brain structures in red? (IMAGE)
Red = primary motor cortex + primary visual cortex and primary auditory cortex
What are the key brain structures in yellow? (IMAGE)
Yellow = unimodal association cortices
NOTICE → One type of sense = unimodal, for example the visual association cortex will only get vision information
What are the key brain structures in green? (IMAGE)
Green = heteromodal association cortex
What are the key brain structures in blue? (IMAGE)
Limbic cortex
What does unimodal mean?
One type of sense = unimodal, for example the visual association cortex will only get vision information = yellow
What is the function of the heteromodal association cortex?
- They put together information provided by various unimodal association areas to accomplish more complex functions
- This follows the concept that information continues to be processed at higher and higher levels as it travels through the brain.
- For example, follow the pathway of information that will start in the primary visual cortex (red), move to the visual association cortex (yellow) and then to the lateral parietal and temporal heteromodal association cortex (green) which will combine information from both vision and motor or audition through a variety of sensory inputs.
Which cortices cover most of the cerebral surface of the brain?
Association cortices (green)
What are the association cortices responsible for?
Responsible for complex processing that goes on between the arrival of input to the primary sensory cortices and the generation of behavior
What is the function of the association cortices?
Loosely referred to as “cognition”
What is cognition?
It is a process by which we come to know the world
What are the 3 main tenants of cognition? And their corresponding main cortex?
- Attending to complex stimuli (parietal cortex)
- Identifying these stimuli (temporal cortex) → recognize
- (Responding) Planning appropriate responses (frontal lobes)
- Restraint
- initiative
- Order
Why is the frontal cortex very important?
The frontal cortex integrates complex information from sensory and motor cortex, and parietal and temporal association cortices.
In order to achieve their functions, association cortices are connected to many of the brain regions. Name the main areas.
- Primary motor and sensory areas
- Thalamus
- Brainstem
- Hippocampus
- Basal ganglia
- Cerebellum
What are the three broad areas of association cortices and functions?
- Parietal association cortex = 1. Attention
- Temporal association cortex = 2. Recognition
- Frontal association cortex = 3. Planning and decision making
What would damage (typically to the right) parietal association cortex yield?
- CONTRALATERAL neglect
- Apraxia = lack ability to plan movement
- We know that the left hemisphere is generally specialized for language, so it leaves the right to mediate things like attention.
- Therefore, when there is damage to the right we see the inability to attend to things on the left.
- We also know that the WHERE pathway, happens in the parietal association cortex, and it analyses the location and movement of visual objects in space.
What would damage (typically to the right) temporal association cortex yield?
- Visual agnosia (e.g. prosopagnosia)
- Typically people can acknowledge and describe the stimulus but they are unable to recognize or report what it is
What would damage (typically to the left) temporal association cortex yield?
- Aphasias
- Because the left side of the brain is typically for language, we see a deficit in language = aphasias
What is the frontal association cortex responsible for other than planning and decision making?
- It is also associated with our personality
- It allows us to appreciate our self in relation to the world, which will allow us to dictate our behaviors to be a plan and executed as we wish them to be
- It plays a big role in our society in terms of social context.
What type of general lesions to these association cortexes produces?
Lesions to association cortex produce characteristic disorders
How did the man with no memory (who had visual agnosia) recognize people?
Through auditory system = hearing the people’s voice
Where does information from various senses come together?
Heteromodal association cortex = green
What is the general patterns of cortical connectivity in our sensory systems?
- Visual
- Eye + retina = rods and cones to the…
- Optic nerve then to the …
- Lateral geniculate nucleus to the …
- Primary visual cortex…
- And now we can add another area = unimodal association areas = so the information can now go to a secondary visual cortex
- And then we can add another layer to this hierarchy = green areas = heteromodal association cortices → this is where information from various senses will get put together.
- Touch
- Skin
- Dorsal column/spinothalamic nuclei
- Thalamus
- Primary sensory cortex (S1)
- The information from these two systems might also combine and come together
How is the neocortex divided?
It is divided into 6 cellular layers (laminae) with distinct cell populations.
What are the similarities between the different cell layers of the neocortex?
In each layer, these cells have similar density, size, and shape.
What are the differences between the different cell layers of the neocortex?
Where they differ is on their inputs and their outputs.
What are the three primary courses of input to the neocortex?
- Brainstem modulatory systems (goes to layers = 6,5,4,3,2,1)
- Other cortical areas (goes to layers 5,4,2,1)
- Thalamus (goes to layer 2)
Is the thalamus involved in our hierarchies that we have covered so far?
Yes, the thalamus is on the pathway, in both the dorsal column medial lemniscus as well as the optic tract
Is the Lateral geniculate nucleus of the thalamus inputs to the association cortices? Why or why not?
- LGN –> gets information from the visual cortex
- These parts of the thalamus receive information from the periphery → not from the cortex
Is the VPL and VPM parts of the thalamus inputs to the association cortices Why or why not?
- VPM and VPL –> typically gets information and gives it to the somatosensory cortex and receives information from the PCML as well as the spinal thalamic tracts
- These parts of the thalamus receive information from the periphery → not from the cortex
What are inputs to the association cortices?
- Pulvinar → parietal association cortex
- Medial dorsal nuclei → frontal association cortex
- They receive information from the cortex = they are receiving information that has already been processed
What is the consequence of having these inputs to the association cortices?
- The consequence of this is that signals going into the association cortex, from these different nuclei, reflect information that has already been processed by = the primary and secondary sensory and motor areas of the brain.
TAKE AWAY FROM ALL OF THIS INFORMATION IS THAT THE THALAMUS IS A HUGE RELAY CENTER!!!
What are the two thalamic nuclei that provide much of the subcortical input to the association cortex?
- Pulvinar → parietal association cortex
- Medial dorsal nuclei (MD) → frontal association cortex
- ***These nuclei receive information from other regions of the cortex (rather than receiving peripheral sensory information).
What are the two types of cortico-cortical connections?
- Ipsilateral connections
- Inter-hemispheric connections
Where do these ipsilateral connections (cortico-cortical connections) come from?
From primary and secondary sensory and motor cortices on the same side of the brain
What are the inter-hemispheric connections (cortico-cortical connections)?
From corresponding and non-corresponding regions of cortex on the other side of the brain (via corpus callosum and anterior commissure.
Where doe these brainstem modulator centers connect?
- They connect up to the association cortices = other primary and secondary sensory cortical regions
