Methods of Cognitive Neuroscience Flashcards
What did Francis Crick propose as a switch for neurons in 1999? How did this materialise?
Light might somehow be used as a switch because it could be precisely be delivered in timed pulses. This materialised in the form of photoreceptor proteins derived from bacteria such as bacteriorhodopsin in halobacterium.
How does bacteriorhodopsin function in halobacterium?
as an ion pump, converting light energy into metabolic energy as it transfers ions across the cell membrane.
What was the key challenge in having photoreceptor proteins control neural activity and how was this resolved?
What branch of science did this open?
Inserting the proteins into the cell, this was accomplished by inserting genes that, when expressed, made targeted cells light responsive. Expose the cell to light, and the neuron would fire. Optogenetics was born
What protein did two graduate students at Stanford, Karl Deisseroth and Ed Boyden use instead and how was this of benefit?
By utilising channelrhodopsin-2 which is encoded using a single gene, making it easier to use molecular biology tools
Describe the process these two graduate students completed with the ChR-2, what were the results of this?
using a technique now called viral transduction, they spliced the gene for ChR-2 and then added this virus (modified rabies virus) to a culture of live nerve cells growing in a Petri dish. The virus acted like a ferry, carrying the gene into the cell. Once the ChR-2 gene was inside the neurons and the protein had been expressed, they projected a light beam onto the cells. Immediately, the targeted cells began to respond. By pulsing the light, the researchers were able to precisely control the neuronal activity. Each pulse of light stimulated the production of an action potential; and when the pulse was discontinued, the neuron shut down.
How did the two students apply this method to live animals?
they implanted a tiny optical fiber in the part of the brain containing motor neurons that control a mouse’s whiskers. When a blue light was pulsed, the whiskers moved
Why infrared light advantageous in optogenetics?
it penetrates tissue, and thus, it may eliminate the need for implanting optical fibers to deliver the light pulse to the target tissue.
How could optogenetics change behaviour in mice in an experiment?
Optogenetic methods were able to reduce anxiety in mice. After creating light-sensitive neurons in their amygdala, a flash of light was sufficient to motivate the mice to move away from the wall of their home cage and boldly step out into the center, only if the light was targeted at a specific subregion of the amygdala.
According to the slides what four mental operations do we carry out when completing a task?
- encode
- Compare
- Decide
- Respond
What are the two “Caveats” about brain function and processing?
Caveat 1: The same brain region can serve different functions at different points in time
Caveat 2: Sometimes processing happens in parallel (at same time) ie can see everyone at once. sometimes processing is serial (steps) ie can’t focus on everyone at once.
What is meant by convergence and complementarity according to the slides?
Convergence: if a theoretical concept can be proven with many different neuroscientific techniques, then it is highly likely true.
Complementarity: precision in time, precision in space, one/ many neurons measured and direct vs indirect measures of the brain.
What is the complementarity style of EEG?
Good temporal resolution, poor spatial resolution
What is the complementarity style of fMRI?
Good spatial resolution, poor temporal resolution
How are correlational and causal results derived from the brain derived?
Brain activity: Correlational
Brain activity manipulations and brain damage: causal
What is the oldest techniques of studying the brain?
Lesions
What observations were made about lesions?
Lead to specific perceptual, cognitive, motor, emotional or motivational problems. Some problems can disappear sometimes as the brain reorganises itself ( neuro plasticity)
