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The model due to Cuppini et al. comprises distinct neural populations for

  1. anterior ectosylvian sulcus (AES) and auditory subregion of AES (FAES)
  2. inhibitory interneurons between AES/FAES and SC
  3. space-coded ascending inputs (visual, auditory) to the SC
  4. inhibitory ascending interneurons
  5. (potentially) multi-sensory SC neurons.

Deactivating regions in AES or lateral suprasylvian cortex responsive to some modality can completely eliminate responses of deep SC neurons to that modality.

Wallace and Stein argue that some deep SC neurons receive input from some modalities only via cortex.

The model due to Anastasio and Patton reproduces multi-sensory enhancement.

Deactivating modulatory, cortical input also deactivates multi-sensory enhancement.

SIV neurons are excited almost exclusively by somatosensory stimuli.

SIV neurons' activity can be inhibited by activity in the auditory FAES.

The function of SIV is unknown.

Dehner et al. speculate that the inhibitory influence of FAES activity on SIV activity is connected to modality-specific attention: According to that hypothesis, an auditory stimulus which leads to strong FAES activity will suppress activity in FAES and thus block out cortical somatosensory input to the SC.

fAES is not tonotopic. Instead, its neurons are responsive to spatial features of sounds. No spatial map has been found in fAES (until at least 2004).

AES has been implicated with selective attention.

Multisensory neurons in AES are mostly located at the borders of unisensory regions.

Multisensory AES cell receptive fields are not well-delineated regions in space in which and only in which a stimulus evokes a stereotyped response. Instead, they can have a region, or multiple regions, where they respond vigorously and others, surrounding those `hot spots', which in which the response is less strong.

AES neurons show an interesting form of the principle of inverse effectiveness: Cross-sensory in regions in which the unisensory component stimuli would evoke only a moderate response produce additive (or, superadditive?) responses. In contrast, Cross-sensory stimuli at the `hot spots' of a neuron tend to produce sub-additive responses.

FAES is not exclusively auditory.

AEV is partially, but not consistently, retinotopic.

Receptive fields in AEV tend to be smaller for cells with RF centers at the center of the visual field than for those with RF centers in the periphery.

AEV is not exclusively (but mostly) visual.

RFs in AEV are relatively large.

Maybe attention controls whether or not multi-sensory integration (MSI) happens at all (at least in SC)? That would be in line with findings that without input from AES and rLS, there's no MSI.

Are AES and rLS cat homologues to the regions cited by Santangelo and Macalluso as regions responsible for auditory and visual attention?

The most important cortical input to the SC (in cats) comes from layer V cortical neurons from a number of sub-regions of the anterior ectosylvian sulcus (AES):

  • anterior ectosylvian visual area (AEV)
  • the auditory field of AES (FAES)
  • and the fourth somatosensory area (SIV)

These populations in themselves are uni-sensory.

There are monosynaptic excitatory AES-SC projections and McHaffie et al. state that "the predominant effect of AES on SC multisensory neurons is excitatory."

Without an intact association cortex (or LIP), SC neurons cannot develop or maintain cross-modal integration.

(Neither multi-sensory enhancement nor depression.)

Descending inputs from association cortex to SC are uni-sensory.

AES integrates audio-visual inputs similar to SC.

AES has multisensory neurons, but they do not project to SC.

AES is a brain region in the cat. We do not know if there is a homologue in humans.

There are modulatory projections from AES to SC. This looks like a parallel to connections in visual cortex, because

  • SC is "low" in the information processing hierarchy and AES is high,
  • projections from SC are topographically organized
  • AES-SC-projections are modulatory.

However,

  • I don't know about the topographic organization and bifurcation properties of the descending projection.
  • I don't know if there are (indirect?) connections from SC to AES and whether they are topographically organized

The auditory field of the anterior ectosylvian sulcus (fAES) has strong corticotectal projections (in cats).

Some cortical areas are involved in orienting towards auditory stimuli:

  • primary auditory cortex (A1)
  • posterior auditory field (PAF)
  • dorsal zone of auditory cortex (DZ)
  • auditory field of the anterior ectosylvian sulcus (fAES)

Only fAES has strong cortico-tectal projections.

Deactivation of AES and rLS leads to a complete lack of cross-modal enhancement while leaving intact the ability of multi-sensory SC neurons to respond to uni-sensory input and even to add input from different sensory modalities.

Rowland et al. derive a model of cortico-collicular multi-sensory integration from findings concerning the influence of deactivation or ablesion of cortical regions anterior ectosylvian cortex (AES) and rostral lateral suprasylvian cortex.

Rowland et al. derive a model of cortico-collicular multi-sensory integration from findings concerning the influence of deactivation or ablesion of cortical regions anterior ectosylvian cortex (AES) and rostral lateral suprasylvian cortex.

It is a single-neuron model.

Cuppini et al. expand on their earlier work in modeling cortico-tectal multi-sensory integration.

They present a model which shows how receptive fields and multi-sensory integration can arise through experience.

The model due to Cuppini et al. develops low-level multisensory integration (spatial principle) such that integration happens only with higher-level input.

In their model, Hebbian learning leads to sharpening of receptive fields, overlap of receptive fields, and Integration through higher-cognitive input.