TY  - GEN
Y1  - 2025///
KW  - Binocularity
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/35077/
AV  - restricted
ID  - heidok35077
N2  - Binocular summation enhances visual discrimination of contrast and
luminance during binocular viewing compared to monocular viewing. This improved binocular detection has mostly been described
in human psychophysics experiments, and therefore the neural circuitry behind it remains unknown. The majority of other binocular
processes, however, originate in the primary visual cortex (V1). Earlier
parts of the image-forming visual pathway have not been thoroughly
explored as a potential source of binocular integration. While some
limited binocular interaction is known to occur in the lateral geniculate nucleus (LGN), retinal ganglion cells (RGC) are considered to be
completely monocular.
In my PhD thesis, however, I used in vivo 2-photon calcium imaging to demonstrate that RGC boutons in the LGN can respond to
stimulation of either eye. Furthermore, these binocular responses were
cell-type-specific, with the stimulation of the opposite eye eliciting different responses in ON and OFF RGC boutons. To confirm that binocularity, observed in the RGC boutons was relevant in further visual
processing I also recorded responses of the LGN boutons in the V1,
showing, that binocular information observed in the RGCs reaches
the cortex. Binocularity of the RGCs boutons in the LGN was surprising, as there are no known connections between the two retinas and
no known axo-axonal synapses targeting RGC boutons in the LGN.
Here, in collaboration with Pietro Micheli I showed, that binocularity,
observed in the RGC boutons didn?t originate locally, rather it was a
result of consensual pupillary constriction. While it has been known
for over a century that due to pupillary light reflex (PLR) pupils constrict consensually, allowing less light to enter the eye, the effect this
change of illumination has on visual processing has not been considered. In my thesis, however, we showed, that stimulating one eye
leads to constriction of both pupils and a consequent visual response
in the RGCs of the non-stimulated eye.
To understand the role of this novel form of binocularity in visual
processing, I compared RGC responses to binocular and monocular
stimulation and observed strong binocular facilitation only at low
contrasts, consistent with binocular summation being calculated on
the retina.
TI  - Pupillary driven binocular interactions in retinal ganglion cells can encode binocular summation
A1  - Lapanja, Tjasa
CY  - Heidelberg
ER  -