PMID- 37070082
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20240216
DP  - 2023 Nov 22
TI  - Neural encoding of multiple motion speeds in visual cortical area MT.
LID - 2023.04.08.532456 [pii]
LID - 10.1101/2023.04.08.532456 [doi]
AB  - Segmenting objects from each other and their background is critical for vision. 
      The speed at which objects move provides a salient cue for segmentation. However, 
      how the visual system represents and differentiates multiple speeds is largely 
      unknown. Here we investigated the neural encoding of multiple speeds of 
      overlapping stimuli in the primate visual cortex. We first characterized the 
      perceptual capacity of human and monkey subjects to segment spatially overlapping 
      stimuli moving at different speeds. We then determined how neurons in the 
      motion-sensitive, middle-temporal (MT) cortex of macaque monkeys encode multiple 
      speeds. We made a novel finding that the responses of MT neurons to two speeds of 
      overlapping stimuli showed a robust bias toward the faster speed component when 
      both speeds were slow (</= 20 degrees /s). The faster-speed bias occurred even when a 
      neuron had a slow preferred speed and responded more strongly to the slower 
      component than the faster component when presented alone. The faster-speed bias 
      emerged very early in neuronal response and was robust over time and to 
      manipulations of motion direction and attention. As the stimulus speed increased, 
      the faster-speed bias changed to response averaging. Our finding can be explained 
      by a modified divisive normalization model, in which the weights for the speed 
      components are proportional to the responses of a population of neurons elicited 
      by the individual speeds. Our results suggest that the neuron population, 
      referred to as the weighting pool, includes neurons that have a broad range of 
      speed preferences. As a result, the response weights for the speed components are 
      determined by the stimulus speeds and invariant to the speed preferences of 
      individual neurons. Our findings help to define the neural encoding rule of 
      multiple stimuli and provide new insight into the underlying neural mechanisms. 
      The faster-speed bias would benefit behavioral tasks such as figure-ground 
      segregation if figural objects tend to move faster than the background in the 
      natural environment.
FAU - Huang, Xin
AU  - Huang X
AD  - Department of Neuroscience, University of Wisconsin-Madison, Wisconsin 53705, 
      USA.
FAU - Ghimire, Bikalpa
AU  - Ghimire B
AD  - Department of Neuroscience, University of Wisconsin-Madison, Wisconsin 53705, 
      USA.
FAU - Chakrala, Anjani Sreeprada
AU  - Chakrala AS
AD  - Department of Neuroscience, University of Wisconsin-Madison, Wisconsin 53705, 
      USA.
FAU - Wiesner, Steven
AU  - Wiesner S
AD  - Department of Neuroscience, University of Wisconsin-Madison, Wisconsin 53705, 
      USA.
LA  - eng
GR  - P51 OD011106/OD/NIH HHS/United States
GR  - R01 EY022443/EY/NEI NIH HHS/United States
PT  - Preprint
DEP - 20231122
PL  - United States
TA  - bioRxiv
JT  - bioRxiv : the preprint server for biology
JID - 101680187
PMC - PMC10107747
OTO - NOTNLM
OT  - discrimination
OT  - divisive normalization
OT  - figure-ground segregation
OT  - natural scenes
OT  - neural encoding
OT  - segmentation
OT  - speed tuning
OT  - transparent motion
OT  - velocity
COIS- Conflict of Interest None.
EDAT- 2023/04/19 06:00
MHDA- 2023/04/19 06:01
PMCR- 2023/11/27
CRDT- 2023/04/18 01:47
PHST- 2023/04/19 06:00 [pubmed]
PHST- 2023/04/19 06:01 [medline]
PHST- 2023/04/18 01:47 [entrez]
PHST- 2023/11/27 00:00 [pmc-release]
AID - 2023.04.08.532456 [pii]
AID - 10.1101/2023.04.08.532456 [doi]
PST - epublish
SO  - bioRxiv [Preprint]. 2023 Nov 22:2023.04.08.532456. doi: 
      10.1101/2023.04.08.532456.