📗 -> 05/05/25: NPB163-L10
🎤 Vocab
❗ Unit and Larger Context
30 minutes late
Continuation of the end of last lecture, covering predictive coding model of sensory systems
✒️ -> Scratch Notes
REVIEW - Everything before diamond / multi-stable percept
Anticipating sensory consequences of own actions
Producing a movement can have sensory consequences (e.g. moving your )
Effery / Correlary Discharge? - predictions made from motor areas
Discussion
Problem Set Sensory Systems 2
- What is a neural map:
Systematic arrangement of neurons with regards to a specific property they are attuned to, or organizing principle
- Receptive fields
- Spatial
- Frequency
- Orientation
- etc.
- How are retinotipc maps in the LGN and V1 similar and different
Similar:
- They both represent neighboring retinal images together
- Both use the polar system
- At ends of map are neurons that represent each end of visual field. Main axis that defines eccentricity, how far they are from center
- Both seperate out visual field
Different:
- Overrepresentation of the center of the visual field in V1
- Cortical magnification
- What is cortical magnification and how does it change with eccentricity
More magnification for things less eccentric (more close to center), less for things more eccentric (closer to edges)
inverse relationship between eccentricity and magnification
- Circular aperture motion
In both cases you would see the local pattern of motion, has to be perpendicular to direction of bars.
Would perceive to be moving up and to the left.
Strongest activation in those that represent up-left, neurons tuned to left OR up would respond but much less. Not a very narrow tuning, still see a weak response for variety of preferences.
Problem Set Sensory Systems 3
- Frequency vs Firing Rate graph questions
a. Approx what cell is it most sensitive to?
Look at the most quiet sensitivity, and find where it is most active.
It is most sensitive to around 20kHz
b. The hair cells of the cochlea that cause this cell to fire are located near which end of the basilar membrane?
Closest to the window.
This is a high frequency, so represented close to the window
- If it were low, it would be represented by the tip
c. What would the intensity-frequency tuning curve look like for this cell
This particular cell has a spontaneous activity of around 50 spikes/s. Now, we look to see what stimulus causes activity above 50.
Now, graphing where the curve first goes above 50.
with x axis being kHz and y axis being dB (frequency and ---)
| kHz | dB |
|---|---|
| 1 | 60 |
| 9 | 40 |
| 15 | 20 |
| 20 | --- |
| 25 | 20 |
| 30 | 40? |
- You’ll get a convex, bowl shape with the center/minima at 20kHz
d. Is this cell tuned to particular sound activity
- It is interesting how many more synapses there are from the periphery to the cortex in the auditory pathway than in the visual pathway given the auditory system is faster. Another difference we see in the auditory pathway is the massive convergence onto IC (Inferior Colliculus) before primary auditory cortex (A1) is even reached. What do you think this suggests given what we have learned about convergence?
Could detect signals of less intensity
Can combine different pathways / processing interpretations and integrate that information
🧪 -> Refresh the Info
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Did a specific aspect of the reading raise questions for you or relate to other ideas and findings you’ve encountered, or are there other related issues you wish had been covered?)
🔗 -> Links
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Connections
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