sreejan_kumar Profile Banner
Sreejan Kumar Profile
Sreejan Kumar

@sreejan_kumar

Followers
2K
Following
727
Media
64
Statuses
506

Joint Postdoc at Columbia @ZuckermanBrain and NYU @NYUPsych. Supported by @NYASciences. Prev at: Princeton PhD, RS Intern @Meta, Yale '19

Joined June 2013
Don't wanna be here? Send us removal request.
@sreejan_kumar
Sreejan Kumar
2 months
I'm excited to share that my new postdoctoral position is going so well that I submitted a new paper at the end of my first week! A thread below
@biorxiv_neursci
bioRxiv Neuroscience
2 months
Sensory Compression as a Unifying Principle for Action Chunking and Time Coding in the Brain https://t.co/QTNBYaYmwo #biorxiv_neursci
1
13
71
@ZIPSeminar
ZIPS
1 month
Our Fall/Winter ZIPS series is starting soon! We will kick it off on October 15th with talks from Drs. @sreejan_kumar and Luis Flores! See details below.
0
1
1
@samnastase
Sam Nastase
1 month
I'm recruiting PhD students to join my new lab in Fall 2026! The Shared Minds Lab at @USC will combine deep learning and ecological human neuroscience to better understand how we communicate our thoughts from one brain to another.
5
101
431
@sreejan_kumar
Sreejan Kumar
2 months
0
0
2
@sreejan_kumar
Sreejan Kumar
2 months
Thanks for reading! Special and huge thanks to my co-first author @matthieulc and senior authors @marcelomattar and Jonathon R. Howlett, as well as co-authors @TrackingPlumes and Lea Duncker! The work wouldn't be possible without all of them.
1
0
6
@sreejan_kumar
Sreejan Kumar
2 months
Second, it's known that we build compressed abstractions of our environments that allow us to generalize. What's maybe not known is that this process is intrinsically tied to forming habits and complex action plans!
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
What are the implications? First, sensory compression is not just in DLS. It's also in other areas such as Hippocampus and Cerebellum. So we predict that wherever there is sensory compression happening, there is also time encoding and support of time-sensitive behaviors.
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
This is because sensory compression produces intrinsic, task-independent time encoding dynamics and these dynamics act as a scaffold to implement timing of task-specific behaviors.
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
We then show it accounts for another result that shows something contradictory: the DLS actively uses sensory stimuli to time and execute motor habits.
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
We then show that this model accounts for seemingly paradoxical findings in time representations in the DLS. First, we show our model explains results that encoding of time in rat DLS is invariant to task relevancy and stimulus properties.
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
We then see that bottleneck models engage these stable neural trajectories that implicitly encode time by where you are in the trajectory.
1
0
4
@sreejan_kumar
Sreejan Kumar
2 months
We show that a model with a sensory bottleneck accounts for many behavioral effects that @gershbrain and @drlucylai characterize in their work on human action chunking, whereas a non-bottleneck baseline does not.
1
0
5
@sreejan_kumar
Sreejan Kumar
2 months
To test our hypothesis on the effect of sensory compression on action chunking and time coding, we developed an RNN model with sensory bottlenecks and trained it on RL tasks that involve chunking.
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
The DLS is known to be a "bottleneck" in sensorimotor processing. Millions of cortical neurons project onto orders of magnitude fewer striatal cells, producing highly favorable conditions for compression.
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
If these functions are co-located, one might believe there's a common mechanism for them. Our work suggests that this mechanism is sensory compression!
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
What's another function the DLS is involved in? Time encoding! According to a review paper by Edvard and May-Britt Moser (2014 Nobel prize winners), the brain tracks time through "stable neural trajectories" where cell populations fire predictably along a trajectory.
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
A region of the brain that's a big driver of action chunking is the Dorsolateral Striatum (DLS)
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
A primary way this manifests in behavior is through action chunking, where predictable action sequences become compressed into cohesive, reusable units. Think of typing a familiar password, phone number, or playing a well-practiced song on an instrument.
1
0
3
@sreejan_kumar
Sreejan Kumar
2 months
Why do we brush our teeth without having to think about it? Our brain can learn habits through repetition. Habits become automatized in that, once they’re formed slowly over many repetitions, we can execute them automatically without having to “think” about them.
1
0
6
@sreejan_kumar
Sreejan Kumar
3 months
Thanks for reading! Tagging some random AI people here that may find this interesting enough to read. @fchollet @AndrewLampinen @ayazdanb @scychan_brains @kaixhin @LakeBrenden @RTomMcCoy @lambdaviking @MLStreetTalk @udayaghai 12/12
1
0
4