For all of those that still follow/reference this site. I wanted to show you the cool stuff we do in the course I’m GSIing now, MCDB 423: Introduction to Research in Cellular and Molecular Neurobiology.
This past week, we tested a new experiment for this course based off of Backyard Brain’s Spiker Box. We have them breadboard the circuit from the schematic! Here’s a few videos to show you how awesome this lab course is for those that are interested in taking it. 🙂
If you are so inclined to take a break from studying, this is a fun application of what we learned 3 exams ago…
Apparently naked mole rats are insensitive to acid…
…and the reason is that they have a mutation in Nav1.7, which if you recall, is responsible for the “gain” on pain, and amplification of that nociceptive signal. So naked mole rats are like those pain-insensitive Indians we read about, cool eh?
Link to io9
Good luck studying, ping me if you would like a screencast on a topic. If I have time, I’ll try to whip something together if there seems to be much confusion over a topic.
Below are discussion exercises for this week concerning visual processing. It covers varying aspects of vision.
The different fields of vision are governed by different anatomical “parts” of your retina. Lesions to certain tracts will effect parts of your vision.
Below is separated streams of information (divided by what you would see), and how that information travels as it reaches the striate cortex.
Center surround organization is a means by which the visual system is able to detect contrast, particularly in the use of edge detection. At the molecular level, it is a function of the connections of the center photoreceptor on the bipolar cell, the connections of the side photoreceptors on the horizontal cells, and the horizontal cells synapsing onto the center photoreceptor cell.
The important thing to note is that the photoreceptors always respond the same way to light / dark, regardless of whether they are part of an on-center / off-surround bipolar cell network or an off-center / on-surround bipolar cell network. The key point which differentiates the response to light or dark is at the level of the bipolar cell and what type of glutamate receptor is expressed.
For On-center, it is a metabotropic receptor which responds to glutamate by inhibiting the bipolar cell. For example, in dark conditions, the glutamate is released from the center photoreceptor and inhibits the bipolar cell, as expected in a On-center bipolar cell. Conversely, for an off-center, it is an ionotropic receptor which responds to glutamate by exciting the bipolar cell. Thus, in dark conditions, the glutamate is released from the center photoreceptor and excites the bipolar cell, as expected in an Off-center bipolar cell.
Center Surround Organization
Below are exercises from discussion w/ answers pertaining to how we encode frequency and localize sound. Furthermore, included is a summary of the auditory pathway.
Auditory Worksheet Answers
Below is the simplified pathways for olfaction, taste, and a comparison/summary of signal transduction pathways.
One thing to note pertaining to cilia and microvilli in olfaction and taste, respectively, is that one of their core functions is to increase surface area and detection capabilities.
Signal Transduction Mechanisms
Below are good resources for understanding the stimulation pattern of hair cells in the semicircular canal.
The thing to keep in mind is that they detect changes in acceleration, rather than absolute velocity. So during acceleration, your hair cells will detect displacement… during constant velocity (over many seconds 10+), your hair cells adapt… and during deceleration (your hair cells need to re-adapt)… This is why one sees increased firing -> baseline firing -> decreased firing rate.
An additional point to make is that if you have angular rotation at a constant velocity for a prolonged period of time, the endolymph itself will also eventually begin moving in the same direction as the direction you are rotating your head. Therefore, once you stop moving your head, there will be a lag with your endolymph in terms of it catching up to “no longer moving.” (because it is not directly attached to your head) For example, if you accelerate a car and suddenly stop without being buckled in… the contents within the car, including yourself, will be thrown from the vehicle. A similar effect occurs with the endolymph. The force of the endolymph when you stop rotating your head will will bend your cilia away from the kinocilia, causing hyperpolarization. This is because your endolymph is still moving while your rotation has stopped, a lag time between endolymph movement and head movement.