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SUMMARY:Visual representations in the human brain rely on a reference fram
 e that is in between allocentric and retinocentric coordinates - Paul Bays
DTSTART:20251114T140000Z
DTEND:20251114T150000Z
UID:TALK240892@talks.cam.ac.uk
CONTACT:Adam Triabhall
DESCRIPTION:This week we will discuss and debate a very recent preprint by
  Servetnik and colleagues (2025).\n\nAbstract: “Visual information in ou
 r everyday environment is anchored to an allocentric reference frame – a
  tall building remains upright even when you tilt your head\, which change
 s the projection of the building on your retina from a vertical to a diago
 nal orientation. Does retinotopic cortex represent visual information in a
 n allocentric or retinocentric reference frame? Here\, we investigate whic
 h reference frame the brain uses by dissociating allocentric and retinocen
 tric reference frames via a head tilt manipulation combined with electroen
 cephalography (EEG). Nineteen participants completed between 1728–2880 t
 rials during which they briefly viewed (150 ms) and then remembered (1500 
 ms) a randomly oriented target grating. In interleaved blocks of trials\, 
 the participant’s head was either kept upright\, or tilted by 45º using
  a custom rotating chinrest. The target orientation could be decoded throu
 ghout the trial (using both voltage and alpha-band signals) when training 
 and testing within head-upright blocks\, and within head-tilted blocks. Im
 portantly\, we directly addressed the question of reference frames via cro
 ss-generalized decoding: If target orientations are represented in a retin
 ocentric reference frame\, a decoder trained on head-upright trials would 
 predict a 45º offset in decoded orientation when tested on head-tilted tr
 ials (after all\, a vertical building becomes diagonal on the retina after
  head tilt). Conversely\, if target representations are allocentric and an
 chored to the real world\, no such offset should be observed. Our analyses
  reveal that from the earliest stages of perceptual processing all the way
  throughout the delay\, orientations are represented in between an allocen
 tric and retinocentric reference frame. These results align with previous 
 findings from physiology studies in non-human primates\, and are the first
  to demonstrate that the human brain does not rely on a purely allocentric
  or retinocentric reference frame when representing visual information” 
 (Servetnik et al.\, 2025).\n\nReference: Servetnik\, M.V.\, Wolff\, M.J.\,
  Chunharas\, C.\, & Rademaker\, R.L. (2025). Visual representations in the
  human brain rely on a reference frame that is in between allocentric and 
 retinocentric coordinates\, bioRxiv\, https://doi.org/10.1101/2025.10.25.6
 84527
LOCATION:https://cam-ac-uk.zoom.us/j/92612577704?pwd=MUtqMjVQdXNmUTVIYjRkM
 G1NUW9GZz09
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