The superior colliculus does not receive any signals from short-wavelength cones (S-cones) in the retina.⇒
Retinal waves of spontaneous activity in the retina occur before photoreceptors develop.
They are thought to be involved in setting up the spatial organization of the visual pathway.⇒
O'Regan and Noë speak of the geometric laws that govern the relationship between moving the eyes and body and the change of an image in the retina.⇒
The geometry of the changes—straight lines becoming curves on the retina when an object moves in front of the eyes—are not accessible to the visual system, initially, because nothing tells the brain about the spatial relations between photoreceptors in the retina.⇒
There are cells in the rabbit retina which are selective of direction of motion.⇒
Some visual processing occurs already in the retina.⇒
Rucci et al.'s system comprises artificial neural populations modeling MSO (aka. the nucleus laminaris), the central nucleus of the inferior colliculus (ICc), the external nucleus of the inferior colliculus (ICx), the retina, and the superior colliculus (SC, aka. the optic tectum). The population modeling the SC is split into a sensory and a motor subpopulation.⇒
In Rucci et al.'s system, the MSO is modeled by computing Fourier transforms for each of the auditory signals. The activity of the MSO neurons is then determined by their individual preferred frequency and ITD and computed directly from the Fourier-transformed data.⇒
(Retinal) visual input to the left SC mainly originates in the retina of the right eye and vice-versa.⇒
The way many sensory organs work naturally provides a homomorphic mapping from the location of a stimulus into the population of peripheral sensory neurons:
The location of a visual stimulus determines which part of the retina is stimulated.
The identity of a peripheral somesthetic neuron immediately identifies the location of sensory stimulation on the body surface.⇒
The identity of peripheral auditory neurons responding to an auditory stimulus is not dependent on the location of that stimulus.
Instead, localization cues must be extracted from the temporal dynamics and spectral properties of binaural auditory signals.
This is in contrast with visual and somesthetic localization.⇒
There is a distinction between two different kinds of bats: megabats and microbats. Megabats differ in size (generally), but also in the organization of their visual system. In particular, their retinotectal projections are different: while all of the retinotectal projections in microbats are contralateral, retinotectal projections in megabats are divided such that projections from the nasal part of the retina go to the ipsilateral SC and those from the peripheral part go to the contralateral SC. This is similar to primate vision.⇒
In primates, retinotectal projections to each SC are such that each visual hemifield is mapped to one (contralateral) SC. This is in contrast with retinotectal projections in most other vertebrates, where all projections from one retina project to the contralateral SC.⇒
The basic topography of retinotectal projections is set up by chemical markers. This topography is coarse and is refined through activity-dependent development.⇒
We do not know whether other sensory maps than the visual map in the SC are initially set up through chemical markers, but it is likely.⇒
If deep SC neurons are sensitive to tactile stimuli before there are any visually sensitive neurons, then it makes sense that their retinotopic organization be guided by chemical markers.⇒
There's a retinotopic, polysynaptic pathway from the SC through LGN.⇒
Divisive normalization models describe neural responses well in cases of
There are monosynaptic connections from the retina to neurons both in the superficial and deeper layers of the SC.⇒
The pulvinar receives direct retinal input.⇒
X-cells in the cat retina can be modeled by the difference of two Gaussian weighting functions.⇒
The optic nerve does not have the bandwidth to transmit all the light receptors' activities. Some compression occurs already in the eye.⇒
Ganglion cells in the retina connect the brain to a small, localized number of photoreceptors. The small population—or the region in space from which it receives incoming light— are called a ganglion cell's receptive field. They respond best either to patterns of high luminance in the center of that small population and low luminance at its periphery, or to the opposite pattern. Ganglion cells with the former characteristics are called "on-center" cells, the others "off-center" cells.⇒
More visual processing tends to occur in the retina the more important the result is (like detecting bugs for frogs or detecting foxes for rabbits) and the less complex the organism (like frogs and foxes).⇒
LGN receives more feedback projections from V1 than forward connections from the retina.⇒
Certain ganglion cells in the frog retina, dubbed `bug detectors', react exclusively to bug-like stimuli and their activity provokes bug-catching behavior in the frog.⇒
The retina projects to the superficial SC directly.⇒