dr kira

methods to investigate neural circuit mechanisms for flexible behaviors:

• virtual reality task (behavioral experiment)

• optogenetics (causal manipulation of neural activity)

• 2 photon calcium imaging (recording of neural activity)

memort signal → navigation choice →

test:

• visual test

• mouse needs to turn to the initial sample cue

• if visual task is black, mouse needs to turn to black area, visual cue and vice versa when it is white

• basically 4 trial types

• virtual reality task pros: precise control of sensory and task variables, compatible with head fixation and neural recoridng, flexible and easily modifiable environments

• virtual reality task cons: reduced snesory realism (limited vestibuar feed back), requires longer training to adapt tot VR, limited generalization to real world behavior

• goals of this task: where and how in the brain this flexible behavior is generated and to understand what underlying neural mechanisms support such neural activity

Once brain region is identified for where flexible behavior is generated, neural activity is observed through two photon calcium imaging.

Calcium indicator injected so that neural activity can be seen.

two photon calcium imaging:

two photon calcium imaging pros:

• cellular and subcellular spatial resolutions

• simultaneous recording from >1000 neurons

• longitudinal tracking of the same neurons

• anatomical and genetic information

cons:

• indirect measurement of spiking activity

• slower temporal resolution than electrophysiology

• limited imaging depth

Question 1:

Is calcium indicator similar to fluorescence when it’s emitting light like that, or are they two completely different mechanisms?

Answer: the calcium indicator is able to show the light because it emits a shorter wavelength than visible light (calcium indicator is a protein that activates this mechanism).