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
What describes most of the cortex covering the cerebral hemispheres?
The neocortex
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 common features of all cortical regions?
- The primary source of inputs and outputs
- Vertical and horizontal axis connections
- Radial alignment
- Interneurons connect functionally similar cell groups
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!!!
Where do the prefrontal cortex and parieto-occipital relay their information?
- They send it to heteromodal association cortices.
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).
Where does medial dorsal nuclei (MD) send their information?
To the frontal association cortex
Where does the pulvinar send its information?
To the parietal association cortex
What are other cortical areas that input to association cortices?
Cortico-cortical connections
They are the main source of input to association cortices
What is the main source of input to association cortices
Cortico-cortical connections
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.
What is an example of a corresponding inter-hemispheric connection?
- Information coming from the contralateral hemisphere, corresponding cortical areas.
- For example, this means frontal association cortices from the right will give information to the frontal association cortices on the left.
What is an example of a non-corresponding inter-hemispheric connection?
- For example, this means that the right temporal association cortices will give information to the frontal association cortices on the left.
What are the brainstem modulatory centers?
- A bit like “dimmer switches” - turn overall activity up or down
- Involved in learning, motivation, arousal, etc.
Where doe these brainstem modulator centers connect?
- They connect up to the association cortices = other primary and secondary sensory cortical regions
What are the brainstem modulatory centers and their neurotransmitters?
- Midbrain → dopaminergic
- Reticular formation → noradrenergic, serotonergic
- Basal forebrain → cholinergic
With this image = explain the 3 main inputs to the association cortices.
- Thalamus
- Corresponding and non-corresponding cortical areas = contralateral hemisphere
- Ipsilateral cerebral cortex
- Brainstem modulatory inputs –> goes to the association cortices
- There is also some connections between the cerebellum and the association cortices
True or false: Each cortical layer has a primary source of input and they all have the same primary source of output.
FALSE = Each cortical layer has a primary source of input and a primary source of output.
True or false: Each cortical layer has both vertical and horizontal connections.
True
True or false: Cells with similar functions wired together into columns arranged radially.
True
How is connectivity different from primary cortices and unimodal association cortices.
- Inputs come from other regions of the cortex (rather than periphery)
- The information has already been processed
- Cortical -cortical connections
- Ipsilateral (primary and secondary sensory/motor cortices)
- Contralateral (corpus callosum and anterior commisure)
- Subcortical connections
- Midbrain (dopaminergic nuclei)
- Reticular formation
- Brainstem
Where do axons from the periphery input?
Primary somatosensory cortex
Where do association cortices get the majority of their input?
- Axons from the periphery
- The frontal lobe
- Other parts of the brain
- I literally have no clue
- Answer = c. Other parts of the brain
