CNS 2 (October 1) Flashcards
What is the outside surface of any organ called?
-cortical surface
Describe this diagram and the organization of grey/white matter
- in cerebral cortex, grey matter is on outside and white matter axon tracks on the inside
- in spinal cord, grey matter is on the inside and white matter axon tracks are on the outside
- allows for neurons in cortex to project down on outside of spinal cord to reach neurons on the inside of spinal cord
- allows for neurons in spinal cord which are taking senations to the cortex to travel on the outside of white matter deep with brain and contact sensory neurons in the cortex
What is cortex versus medulla?
-cortex is outer surface, medulla is deep
What are the two major areas of deep grey matter to consider?
- thalamus
- basal ganglia
What is the thalamus repsonsible for?
- gateway to brain for emotions in anterior, motor systems in middle, and sensory sytems in posterior thalamus
- way that periphery communicates with overlying cortex
What is the basal ganglia?
-collection of cell bodies repsonsible for initiating and stopping motor movements
What are reciprocal connections?
-connections between cortex and deep grey matter
What are fissures, sulci, and gyri? What do they do?
- fissures: deep invaginations in brain
- sulci: shallow invaginations in brain
- gyri: surface area of brain on either side of sulci
- they divide the brain into lobes
What area of the brain is the precentral gyrus? What are its functions?
- primary motor cortex
- initiates a motor movement by sending axons to spinal cord to cause muscles to contract
What area of the brain is the postcentral gyrus? What are its functions?
- primary sensory cortex
- neurons located here which receive sensory input from the skin, muscles, etc.
- for conscious evaluation of environment
Label the coloured areas
- green: central sulcus
- purple: lateral (sylvian) fissure
- red: precentral gyrus (primary motor cortex)
- blue: postcentral gyrus (primary sensory cortex)
How is the cortex organized at the microscopic level?
- divided into columns
- each column contains approx 10 000 neurons
- cortical columns each have their own computing power
- example about cat eye being blinded; could observe that areas of the brain were darker in the eye that could see (more glucose metabolism). Shows that you have cortical columns dominated by one eye and some that are dominated by the other eye.
What area of the brain is located in front of the primary motor cortex? What is it responsible for?
- frontal lobe
- associating things, putting together motor and sensory info together to make decisions, intellect, planning complicated motor movements
- compared to motor cortex; motor cortex sends the signal out to the spinal cord whereas how you make the motor movement is being done in frontal lobe
What area of the brain is located posterior to the primary sensory cortex? What is it responsible for?
- parietal lobe
- all of sensations are coming together and integrating between touch, smell, vision, etc.
Where is the auditory cortex located?
- temporal lobe
- when you listen to sounds, this area is responsible for perception of those sounds
What are the functions of the occipital lobe?
- visual cortex
- when you see something through L and R eye, they are coming into the brain and sorting themselves into the appropriate L and R cortical columns
What is the area in the frontal cortex involved in vision?
- frontal eye field
- receives a lot of visual input too but two eyes have to be coordinated in their movement together so makes sense to have some visual input in this area
- visual info going in here in order to make planning about how you are going to move your eyes
Where are the two areas for speech located?
- top of temporal lobe: Wernicke’s area
- front of the brain in frontal lobe: Broca’s area
- inability to produce speech could indicate a problem in either area but the way that the speech is not able to be made will tell you which area the problem is in
What is the function of Wernicke’s area? What is the function of Broca’s area?
Wernicke’s area:
- dictionary responsible for sorting words you hear and identify their meaning
- put the dictionary together to make sentences
Broca’s area:
- plan motor movements to create the sounds
- make mouth, larynx, and tongue move
Label the diagram
- Primary motor cortex
- Primary sensory cortex
- Parietal lobe
- Occipital lobe
- Temporal lobe
- Wernicke’s area
- Broca’s area
- Frontal lobe
- Frontal eye field
Where are areas of the brain located responsible for olfaction?
- bottom of brain (under frontal lobe area)
- inside surface of temporal lobe
- deep within lateral fissure
Where are areas of the brain located responsible for gustation?
-parietal cortex
Describe the sensorimotor organization of the precentral and postcentral gyri
-more sensory/motor cortical neurons dedicated to upper limbs and lower limbs than trunk
What are white matter tracts?
- axons
- deep within cerebrum there are axons
- axons project (sometimes just go from one cortical column to adjacent cortical column- important in visual cortex to coordinate eye movement to calculate distance) and connect different parts of the brain
What are projection fibres?
- connecting cerebral cortex/parts of NS to other parts of the brain
- ex: interal capsule
Which part of the diencephalon is located on the third ventricle?
-thalamus
Where is the limbic system located? What does it consist of?
- loop of neurons which are located around the inside of the ventricles
- consists of amygdala, hippocampus, fornix, mammilary bodies
What is located around the outside of the ventricles?
- basal nuclei (ganglia)
- system of neurons
- consists of: caudate, lentiform nuclei, amygdala
Describe each coloured structure
- pink is limbic system
- blue is ventricle system
- green is basal ganglia
Describe each coloured structure
- pink is limbic system
- green is basal ganglia
- blue is ventricle system
What are episodic memories?
- deeply entrenched in limbic system
- located in medial temporal lobe (thalamus, amygdala, hippocampus)
- ex: event memory (wedding, pizza party)
You are looking at a brand new red Porsche. Describe how this gets put into episodic memory.
- info comes into various areas of cortex (visual cortex: red colour, smell: leather smell, touch: touch of leather in somatosensory cortex)
- they are gathered from overlying cortex where sensations first come in then go into the cingulate gyrus (shaped like C to communicate with all overlying cortex where the functions are located)
- cingulate gyrus: has cortical connections with overlying cortex, front part is responsible for reality check
- info about car comes into cingluate cortex then goes into the hippcampus where it is unified as “new car”
- from there, goes through mamillary bodies and connects with smell/emotional component of memory (smell of leather and pleasure of seeing this new car)
- then goes back to cortex through anterior part of the thalamus (key relay station for cortex)
- information then goes back to cingulate cortex
- it can then go back and forth to the brain or it can loop through the cingluate cortex again
What are the two ways to activate the premotor cortex regarding procedural memory? How is the activation decided?
- through cerebellum or basal nuclei
- thalamus chooses best pathway to send to premotor cortex
Why do we observe profound effects on memory in Alzheimer’s?
- long term memories are stored over cerebral cortex
- atrophy of cerebral cortex observed in Alzheimer’s
- can see grey matter reduced
- in biopsy, can see strange protein tangles on inside of brain which is consequence/cause of neuronal cell death
- causes inability to recall recent and past memories, lack of attention, disorientation, language problems, and lack of problem solving
What happens in hippocampal atrophy?
- neurons have loss of dendrites and are simpler (less synaptic input to neurons)
- people have amnesia
- inability to store new memories of events after injury (anterograde amnesia), inability to consolidate events, inability to recall past events (retrograde amnesia)
Label the diagram
- caudate (head)
- lentiform nucleus (putamen and globus pallidus): putamen is pink then deeper globus pallidus
- caudate (tail): goes deep inside temporal lobe
- amygdala: responsible for initiating stereotypical movements (eg. copulation)
- substantia nigra: neurons have melanin granules in them so can look at slice through the brain and they are pigmented
Describe the pathway of information of motor movement through basal nuclei
- info goes from motor cortex (looking for plan to walk, get out of chair, etc)
- goes to caudate nucleus and gets a bit of plan, then to lenticular nuclei, then relays to thalamus and goes back to original part of brain that asks for the plan to begin with
- motor cortex asks for plan on the same side of the cortex, goes into ipsilateral basal nuclei, gets plan, feeds back to cortex
- fast
