Lightnews — Scholar-powered news

Matías Goldin @matigoldin.bsky.social · Jun 12

13/
Thanks to @tom-quetu.bsky.social, @touchmovelab.bsky.social, and our supporters:
@frm-officiel.bsky.social, @fondationdefrance.bsky.social , @ec.europa.eu, @agencerecherche.bsky.social, @c-brains.bsky.social.

Matías Goldin @matigoldin.bsky.social · Jun 12

12/
We propose that sweep coding in layer 5a may be related to texture decoding.
The longer integration time makes it possible to combine current sensory inputs with modulatory signals — possibly motor-related — from higher order POm.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

11/
This reveals a new dimension in thalamocortical computation:
🔹 Fine, fast features like sticks are inherited from thalamus
🔸 Broader, global features like sweeps are computed in cortex via temporal integration

1

Matías Goldin @matigoldin.bsky.social · Jun 12

10/
So where do sweeps come from?
In layer 5a, we found that sweep-tuned neurons integrate stick inputs from VPM and POm over longer timescales.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

9/
Recordings in VPM and POm showed that both thalamic nuclei primarily encode sticks.
POm adds some diversity, but sweep tuning is not clearly present.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

8/
Sticks dominated in layer 4 and 3.
Sweeps were found in layers 5a and 5b.
But can these features be inherited from the thalamus?

1

Matías Goldin @matigoldin.bsky.social · Jun 12

7/
We identified two distinct types of responses in the cortex:
🔴 Sticks — brief, fast, single-whisker deflections
⚫ Sweeps — broad, multi-whisker movements with large angular changes
These were tuned to perpendicular axes in the feature space.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

6/
We confirmed this with an independent sparse noise stimulus — random single-whisker deflections — and separated the two functional populations.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

5/
But cells were not uniformly selective across this space.
They tended to cluster around two specific feature angles — suggesting a subspace tuning.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

4/
We found that the whisker movements that elicited the strongest responses belonged to a low dimensional feature space.
We could project each cell’s preferred stimulus into this space: the closer to the edge, the more selective.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

3/
Velocity came out on top, as seen in rats (Harrell et al. 2020), and contrary to stick-slip models where velocity and acceleration are encoded equally.

1 1

Matías Goldin @matigoldin.bsky.social · Jun 12

2/
We designed Gaussian white noise stimuli — optimized to test position, velocity, acceleration — to find which parameter was best encoded by neurons.

1 1

Matías Goldin @matigoldin.bsky.social · Jun 12

1/
We used a unique setup: 24 whiskers deflected with micrometer precision and millisecond timing.
This allowed us to deliver naturalistic, reproducible input across the full whisker pad, while recording neurons multiple in the barrel cortex.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

🧵New preprint from @tom-quetu.bsky.social and me, done in Dan Shulz’s lab @touchmovelab.bsky.social at @neuropsi.bsky.social :
We uncover how a tactile code emerges in cortical layer 5a from temporal integration of thalamic input.
www.biorxiv.org/content/10.1...
Let’s break it down 👇

www.biorxiv.org

1 4 5

Matías Goldin @matigoldin.bsky.social · Jun 12

13/
Thanks to @tom-quetu.bsky.social @touchmovelab.bsky.social , and our supporters:
@frm-officiel.bsky.social , @fondationdefrance.bsky.social , @ec.europa.eu , @agencerecherche.bsky.social , @c-brains.bsky.social

Matías Goldin @matigoldin.bsky.social · Jun 12

12/
We propose that sweep coding in layer 5a may be related to texture decoding.
The longer integration time makes it possible to combine current sensory inputs with modulatory signals — possibly motor-related — from POm.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

11/
This reveals a new dimension in thalamocortical computation:
🔹 Fine, fast features like sticks are inherited from thalamus
🔸 Broader, global features like sweeps are computed in cortex via temporal integration

1

Matías Goldin @matigoldin.bsky.social · Jun 12

10/
So where do sweeps come from?
In layer 5a, we found that sweep-tuned neurons integrate stick inputs from VPM and POm over longer timescales — and are probably modulated by POm.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

9/
Recordings in VPM and POm showed that both thalamic nuclei primarily encode sticks.
POm adds some diversity, but sweep tuning is not clearly present.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

8/
Sticks dominated in layer 4 and 3.
Sweeps were found in layers 5a and 5b.
But can these features be inherited from the thalamus?

1

Matías Goldin @matigoldin.bsky.social · Jun 12

7/
We identified two distinct types of responses in cortex:
🔴 Sticks — brief, fast, single-whisker deflections
⚫ Sweeps — broad, multi-whisker movements with large angular changes
These were tuned to perpendicular axes in the feature space.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

6/
We confirmed this with an independent sparse noise stimulus — random single-whisker deflections — and separated the two functional populations.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

5/
But cells were not uniformly selective across this space.
They tended to cluster around two specific feature angles — suggesting subspace angle tuning.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

4/
We found that the whisker movements that elicited the strongest responses belonged to a low dimensional feature space.
We could project each cell’s preferred stimulus into this space: the closer to the edge, the more selective.

1

Matías Goldin @matigoldin.bsky.social · Jun 12

3/
Velocity came out on top, as seen in rats (Harrell et al. 2020), and contrary to stick-slip models where velocity and acceleration are encoded equally.

1 1