Zeena Rivera ✨they/them✨ has a poster @ SfN & is defending soon👀
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zeenarivera.bsky.social
Zeena Rivera ✨they/them✨ has a poster @ SfN & is defending soon👀
@zeenarivera.bsky.social
100 followers 140 following 24 posts
motivated scientist decides to study motivation & decisions


@UCLA Neuroscience #NSF GRFP #HHMI Gilliam
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zeenarivera.bsky.social
(4/4) I'm doing a couple more experiments before I finish up my PhD & oooweee it's nice to use a task that rats learn quickly w/ a lot of interesting outputs.

Work done in part thanks to @hhmi.org w/ the best collab btwn @aliciaizquierdo.bsky.social & Andrew Wikenheiser. best co-mentorship eva!
November 4, 2025 at 12:32 PM
zeenarivera.bsky.social
(3/4) A couple years back, Andrew and I were talking about how PR, given a consistent work rate, kinda looked like a depleting patch (re: foraging). Now, applying optimality modeling, we find that our rats "overharvest" similarly to (other) patch-leaving tasks 🤯.
Rats' strategies were correlated with, but systematically greater than, the optimal bout length. The model-determined optimal bout length is plotted against the median bout length observed in each session. Observed bout length was strongly correlated with the model-predicted optimal bout length. However, nearly all points fall above the dashed unity line, indicating that rats frequently performed longer bouts than predicted by the model. Histograms along the x- and y-axis show density estimates computed separately for 60 s and 10 s reset delay data.
November 4, 2025 at 12:32 PM
zeenarivera.bsky.social
(2/4) Bout (length of time pressing for reward between no-access delay periods) length & frequency are sensitive to delay length. ***Note, the differences in the y-axis.
Ratio resets segmented PRR task performance into bouts of work. Cumulative records of active lever presses are plotted for the first 800 s of three example sessions. Grey tick marks indicate reward delivery times. (A) In PR task sessions, rats earned reinforcers quickly at the beginning of sessions, but reward rate decreased as the ratio requirement progressed. Example record from session 2 of PR. In PRR sessions (B–C), lever pressing was segmented into bouts by ratio resets, which resulted in the reset delay (shaded regions). Example records of session 2 PRR-60 (B) and session 2 PRR-10 (C). Because reset presses returned the ratio requirement to one, cumulative records for PRR-10 and PRR-60 sessions were computed separately for each bout of work between successive ratio resets. Note the very different y-axes between the three example sessions.
November 4, 2025 at 12:32 PM
zeenarivera.bsky.social
(1/4) TL;(please still)R on #eNeuro

Rats can reset PR to its easiest difficulty by paying a delay cost on PRR task. They adaptively use the reset lever to go from receiving ~67 pellets (PR) ➡ ~210 pellets (PRR w/60s delay)➡ ~328 pellets (PRR w/10s delay; almost 15g 😳) w/in the same amount of time.
Rats were tested on the Progressive Ratio with Resets (PRR) task where 2 levers are present in an operant box. In this example, the left-side lever allows for the rat to do progressive ratio (PR) which starts at a requirement of 1 lever press & increases by 1 lever press. to earn reward (one 45mg sucrose pellet delivered in a hopper). The right-side lever resets the ratio requirement after a fixed reset delay where they cannot press either lever. Rats can press this lever at any point during PR. In PRR-10 sessions the reset delay was 10 seconds, while in PRR-60 sessions the reset delay was 60 seconds.
November 4, 2025 at 12:32 PM
Reposted by Zeena Rivera ✨they/them✨ has a poster @ SfN & is defending soon👀
brainapps.bsky.social
Next @zeenarivera.bsky.social from UCLA for the first blitz talk on a progressive ratio task using effort.
November 4, 2025 at 10:19 AM
Reposted by Zeena Rivera ✨they/them✨ has a poster @ SfN & is defending soon👀
jeremymberg.bsky.social
2/2
This means individuals in the following statuses at the time of application are eligible: Undergraduate in the final (senior) year of a bachelor’s degree program Bachelor’s degree-holder with NO enrollment in a graduate degree program (non-degree graduate coursework allowed) Individual enrolled in a joint bachelor’s-master’s degree program with at least three undergraduate years completed First-year graduate student in their first graduate degree program with less than one academic year completed in the degree program (according to institution’s academic calendar) Individuals enrolled in joint bachelor’s-master’s degree programs are considered graduate students. For GRFP, joint bachelor’s-master’s degrees are defined as degrees concurrently pursued and awarded. Not be a current NSF employee. Applications that do not meet eligibility requirements will be returned without review as being ineligible for a fellowship.
September 26, 2025 at 7:59 PM
zeenarivera.bsky.social
Congrats! Very exciting work
July 30, 2025 at 5:37 PM