Localisation of Learning and Memory Flashcards
Local or Global Localisaton of Memory
If learning is distributed, it’s often because the task involves several bits of _______ that involve different brain _____. SO there does seem to be localisation of learning, but often these parts might come together in a task. This lecture focuses on the ______ and the _______.
distributed
areas
hiipocmapus
cerbellum
Hippocampus and Place Memory
There have been many studies on the role of the hippocamus. In particular, there is a lot of evidence on the role of the hippocampus in _____ memory and ______.
This might be related to ______ memory, but this is hard to study in rats. But this makes sense becuase episodic memory relies on space. You need spatial awareness to have meaningful episodic memory.
spatial
navigation
episodic
Hippocampu and Spatial Memory
What experiments have been done to implicate the hippocampus in spatial memory?
- 8 arm radial maze
- morris water maze
- fMRI studies in humans
8 arm radial maze
- food at the end of these arms…very simple and natural task.
- You can measure how good it is at this task by seeing how many errors it makes going down an arm it’s already gone down. After a while it learns the food won’t be replenished, and it remembers where it has already been before. Over time, rat makes fewer and fewer errors. Fornix, major outout of the hippocampus - when removed it these rats are not as good at the task. So the hippo has a role in informing the animal where it’s already been.
Moris water maze - rat has to find it’s way to a platform. Trained rtats will find platform straight away, but those with the hippo removed will not be able to find it.
Activation of hippocampus while people navigate a virtual town in computer - have to get a sense of the layout, etc
Hippocampal Place Cells
Place cells are neurons in the _______ that have a _______ field based on where the animal is in ______. These cells fire when the animal is in a particular place. There is some sort of stimulation when the animal is somewhere in ________ space (organisational structure defined by relations among objects, not the observer). This pattern is seen across different _____. It doesn’t matter is the animal is looking left, right, or lying on it’s back, it’s just about spatial _______.
Eg: visual receptive field, somatosenory cortex
These sensory fields are responsive to multiple ________. They can often be driven by ______ inputs, but also by others (tactile, olfaction, etc). We know this because the same cells fire even in the _____.
PROPERTIES
- Once the rat knows the environment, the same cells will respond to the same location in space. They are location ______ (only respond to that one location) BUT it is not just specific to that environment. They are not speciifc to a location in the ______. Eg: one cell response at home at the door, but that same one might respond at the bench in the park.
- Place cells are ____-_______ (they are active in that space regardless of which way rat is looking). If there’s food everywhere, it doesn’t matter which way it’s facing, it just recognises it finds food in a particular location. But if it knows it won’t find food in a particular direction then it will care about direction.
Eg: driving up a street - they don’t care which direct you’re heading in, they just have particular cells for particular locations in this street, but if it’s a one-way street they would care.
hippocampus
receptive
space
allocentric
days
location
modalities
visual
dark
visual
specific
world
non-directional
What do place cells do?
Provide animals of a mental ____, so they can recognise where they are and find things in that environment. Even if you move extraneous cues, the rat follows the place cells. And it the maze is rotated, it still follows where the place cells are. So the place cells control it’s _______.
map
behaviour
How do we obtain place cells?
They are created by our experiences in an environment. When we enter a new environemnt we learn new things about it. We have to create spatial receptive fields and maintain them.
If two environments are similar, the place cells will generalise across these environemnts initally, but with lots of exposure they will learn to discriminate them.
Most of the input to the hippocampus comes from…
AND there are cells in this cortex…
…medial entorhinal cortex
…called grid calls that show sensitivity to spatial location…provides the building blocks for the hippocampus
Grids cell in the medial _______ cortex don’t discriminate been ________ or locations. Rather, they are like broad place cells, following a lattice or _____ structure. We know this because they repond to patches that are equally spaced apart in a ________ shape.
They don’t encode a particular place, by provide information about _____ space. They provide information about the _________ frame of ________ of that arena and provides this infomation to the hippocampus.
They retain this pattern regardless of chnages in ______ or _______. This pattern emerges becuase they’re connected in a network - shirt-range ______ and long-range ______.
“neurons that fire together wire together”
entorhinal
environments
grid
hexagonal
any
coordinate
reference
speed
direction
excitation
inhibition
A single grid cell provides ambiguous informaton about location…so how can it provide information about location?
One grid cell only tells you that you could be in one of the black areas.
BUT they don’t all respond in the same gird pattern. The grid patterns very in spatial frequnency. The overlap between these layers tells you where you are (from the combination of information).
This feeds into hippocampual place cells to help them with location
Cerebellar contributions to learning
Cerebellum is involved in learning ______ skills. It’s complex structure allows for the integration of ______ inputs for precise _____ and sequencing of motor _______.
It’s cell structure is very interesting….there are 3 cell types:
- Granule _____ - give rise to parallel fibres
- ______ fibres - input from inferior olive
- _______ cells - output - tree of dendrites
motor
sensory
timing
programs
cells
climbing
purkinje
Describe the cellular structure of the cerebellum
3 cell types:
INPUTS
Climbing fibres - from inferior olive - all over the dendrites of purkinje (one-to-one relationship)
Granule cells - give rise to parallel fibres - deeper in the cerebellum, but when they get closer to the cortex they’re parallel to the surface - pass through the brances of purkinje cells - make small synaptic contact with many purkinje cells
OUTPUTS
purkinje cells - dense - treelike
SO purkinji cells have opposite inputs from granule cells and climbing fibres - large influence from a single climbing fibre (smothering) and lots of small inputs from many grandule cells.
One of the most studied conditioned responses to illustrate cerebellar learning is eyeblink conditioning. Usually this is done with a noise and then airpuff to the eye. Airpuff naturally makes eye blink, and you can condition that when it hears the noise it will also blink. This is a learned conditioned response - how does the NATURAL (US) response work?
This is a very short, 2 synapse, super-fast circuit.
Airpuff sensed by the eyeball (trigeminal nerve) –> takes information to trigeminal nucleus (in the brain stem) –> transferred through cranial motor nucleus –> abducens nerve pulls eye lid down
One of the most studied conditioned responses to illustrate cerebellar learning is eyeblink conditioning. Usually this is done with a noise and then airpuff to the eye. Airpuff naturally makes eye blink, and you can condition that when it hears the noise it will also blink. This is a learned conditioned response, and we know the whole process of it. How do we know about the process (overall?)
We know this because damage to any of these results in the CR to the noise, but not to the airpuff.
One of the most studied conditioned responses to illustrate cerebellar learning is eyeblink conditioning. Usually this is done with a noise and then airpuff to the eye. Airpuff naturally makes eye blink, and you can condition that when it hears the noise it will also blink. This is a learned conditioned response, and we know the whole process of it. This involves all the things that the UR does but…
MORE!
One of the most studied conditioned responses to illustrate cerebellar learning is eyeblink conditioning. Usually this is done with a noise and then airpuff to the eye. Airpuff naturally makes eye blink, and you can condition that when it hears the noise it will also blink. This is a learned conditioned response.
What is the role of the Red nucleus? How do we know this?
See diagram
One of the most studied conditioned responses to illustrate cerebellar learning is eyeblink conditioning. Usually this is done with a noise and then airpuff to the eye. Airpuff naturally makes eye blink, and you can condition that when it hears the noise it will also blink. This is a learned conditioned response.
What is the role of the Pontine nuclei? How do we know this?
See diagram
One of the most studied conditioned responses to illustrate cerebellar learning is eyeblink conditioning. Usually this is done with a noise and then airpuff to the eye. Airpuff naturally makes eye blink, and you can condition that when it hears the noise it will also blink. This is a learned conditioned response.
What is the role of the Inferior Olive? How do we know this?
See diagram
One of the most studied conditioned responses to illustrate cerebellar learning is eyeblink conditioning. Usually this is done with a noise and then airpuff to the eye. Airpuff naturally makes eye blink, and you can condition that when it hears the noise it will also blink. This is a learned conditioned response.
What is the role of the Cerebellum? How do we know this?
See diagram
One of the most studied conditioned responses to illustrate cerebellar learning is eyeblink conditioning. Usually this is done with a noise and then airpuff to the eye. Airpuff naturally makes eye blink, and you can condition that when it hears the noise it will also blink. This is a learned conditioned response.
What is the neural circuit?
See diagram
One of the most studied conditioned responses to illustrate cerebellar learning is eyeblink conditioning. Usually this is done with a noise and then airpuff to the eye. Airpuff naturally makes eye blink, and you can condition that when it hears the noise it will also blink. This is a learned conditioned response.
How does the neural circuit relate to the input and output cells of the cerebellum?
See diagram
