We care about brain stuff
blogged by a 2nd year PhD student in neuroscience
Brain Hat, do you dare to wear it?
Asked by beautifulwintersnow4 beautifulwintersnow4
Thank you for the compliment. It depends on which post you are talking about. I try to write down most of the posts in my own words or at least the essence of other article. Occasionally I move other posts directly to my blog, however in which case I will also post the original source.
Informative science video from one of my favoriate youtubers, vividly described how sound was heard by our ears.
Lateral inhibition is very widespread within the nervous system. The general phenomenon is that excitation of a neuron is inhibited by nearby neural activity. The specifics of the phenomenon take many forms in different parts of the nervous system.
A) A typical receptive field with an inhibitory surround is shown with a “Mexican hat” model, where excitation is shown by a peak and inhibition is shown by a surrounding valley. A single point stimulus generates the same pattern in the spatial distribution of evoked neural activity within the brain.
B) A major function of lateral inhibition is believed to be the sharpening of discrimination, as shown for a two-point stimulus.
This depiction demonstrates “sharpening” of the focus of neuronal activity by lateral inhibition. At A1, the nervous system is assumed to lack lateral inhibition, so excitation spreads spatially via divergent axonal connections. The effect of adding inhibitory interneurons is shown at B1. The right side of the figure shows a graphical representation of the same thing.
The “darkened intersections” illusion can be explained by lateral inhibition. At the intersections, more of the visual receptive field surrounds is covered by light than elsewhere along the white lines. Thus there is more lateral inhibition at the intersections and a darker appearance. The illusion depends on having visual receptive fields with central excitatory regions very roughly the size of the width of the white lines. When you look directly at an intersection you place the very tiny receptive fields of the fovea at it, and the illusion disappears. If the illusion does not work for you, try viewing from a different distance in order to get the right relation of receptive field sizes to line width.
The well-known Muller-Lyer illusion (left) cannot be explained easily by lateral inhibition (though people try). It may relate to higher-order perceptual processes that interpret the leftmost figure as an intersection of two walls receding toward the intersection and its neighbor as an intersection of two walls extending toward the viewer. Since the leftmost vertical line is farther away than its neighbor, it must be longer. Similarly, the Ponzo (railway lines) illusion may be based on interpretation of the near vertical lines as parallel objects receding into the distance.
These illusions may be the result of lateral inhibition between neurons sensitive to different visual slants (orientation detectors).
The twisted cord illusions, or Fraser illusions, also may be the result of inhibition between neurons selective for visual orientation. The lines of the letters of the word “LIFE” are vertical and horizontal, though they appear slanted.
This is what happened inside your guitar. This guy puts an iphone into his guitar. Quite amazing string vibration.
5d old mouse motor neurons from the spinal cord of the standard transgenic mouse model of ALS.
The cone-shaped image is electrode injecting Ca2+ dye into a motor neuron.