Frontal cortex in multisensory intergration Flashcards
Most of the cards will be on the neruopixel probes he created and optogentics
What are neruopixel probes
An electrophysiology tool to record neuronal activity
Advantages of the apollo implant developed by Bimbard et al, 2025
(1) allow stable recordings of neurons for weeks#
(2) allow reuse of the probes after explantation
(3) be light enough for use in mice.
(4) recorded in freely moving mice.
How do mice integrate spatial visual and auditory information?
In additive manner
Which regions of mouse cortex are required for audiovisual intergration?
Audiovisual: Secondary Motor Cortex–MOs
How to calculate audiovisual intergration
Weigh the audio and visual cues together and intergrate - based on optimal biomodal likelehood
Brain region for visual trials
Visual cortex
Brain region for auditory trials
Auditory cortex
Is parietal cortex implicated in multisensory intergration
parietal cortex, are implicated in multisensory processing
(Raposo, Licata, Yau, Song)
o But inactivation may not impair multisensory integration. (Raposo-2014)
(Bizley paper) These interactions may not be needed for audiovisual behaviors.
o Perhaps there are stimulus-driven movement confounds (Bimbard-2021)
What were the 3 problems and 3 solutions to investigate audiovisual intergration from the V1?
1 Problem: Limited trial numbers make modelling integration strategies difficult
Solution: Head-fixed mice robustly perform visual localization tasks with large (up
to 1000) trials per session (e.g. The International Brain Laboratory, 2020)
2 Problem: Focusing on specific regions before establishing a causal role
Solution: Causally test entire dorsal cortex with optogenetic techniques that allow
brain regions to be reversibly inactivated on individual trials (e.g. Guo et al, 2014)
3 Problem: Small neural numbers limit our understanding of neural populations
Solution: With new techniques, large neural populations can be recorded across
multiple brain regions during behavior (e.g. Steinmetz et al, 2019)
What is there a need for in researching the visual cortex
Need for unbiased recording device of cortex so they developed the neuropixels
How much variance was captured in their additive model and why was this good?
97% variance idk why?
On which trials did mice respond faster and why?
Audiotry tasks (corroborates previous studies since auditory is processed faster than vision).
Why were mice slower on A&V intergration trials?
Presumably because it accounts for how V and A were being processed and intergrated together in the cortex.
How did they find which brain region invovled in AV intergration?&WHAT WAS THE ADVANTAGE
Transgenic mouse with Transcrainial optogentic inactivation using excitatory opsin stimulating GABA to silence cortex.
Silenced cortex portion by portion-
ADVANTAGE-UNBIASED testing of each brain region
What happened when they inactivated the Secondary MO
they see a vertical shift of results that are outside the bounds of odds they previously set up. Also saw a decrease in sensory sensitivity
ALSO Superior collliculus causes increased ipsilateral bias but no change to sensory sensitivity so SC is also involved. So SC is affecting the decision making, not the integration role
What can the neruopixel do
track neural population across learning and behaviours.
This reuires stable chronic neruopicel implants so that they do not drift (Sonja)
More shanks so record from more sites
What are pure tones versus complex tones
pure tone- only a single frequency. It’s wave form is a pure sine wave.
A complex tone is not a pure sine wave but it is periodic–it has an underlying pattern that repeats.
