A nice paper on the egocentric generation of the location signal

#1

Brain-Inspired Coding of Robot Body Schema Through Visuo-Motor Integration of Touched Events

The body schema is the perception that each individual has of his own body in space. The acquisition of this body schema during infancy helps to learn a structural organization of the body parts and their visual shape, to establish the boundaries of the body and to situate better its physical limits . Gradually, the body schema grows to enhance spatial awareness to objects (reaching and grasping) and to others (self-other differentiation, eye-gaze). In order to guide the movement of the body in space and to allow interaction with an immediate environment, the brain must constantly monitor the location of each body part at different postures and to analyze the spatial relationship between body parts and neighboring objects.This process requires the integration of proprioceptive, tactile, visual, and even auditory information to align the different reference frames from each other; for instance, eye-, hand-, torso-, or head-centered reference frames.

2 Likes

#2

I have a theory that your personal space is the regions you can interact with directly using your body.
The mapping of your body in this space will include what it looks like with your hands and feet placed in this space.

This interpersonal space is special because it is the direct extension of your sense of self and agency.

Put in a different way - you learn all the ways your joints and support/vestibular system can be combined and at the same time your vision learns what it is like to see you in these places. This body mapping includes your head and eye positions relative to both your body and the supporting surface. This mapping is the fused location signal that is built up in the parietal lobes.

This constructed location signal is what is often referred to indirectly in much of the Numenta literature.

I should add that the mapping from ego-centric space starts here. The world around you is at “the other end” of your vestibular system and support/balance system - the reference frame that you use to anchor your interpersonal space. This mapping of your body is the transformation matrix back to the rest of the world.

If you find this general topic interesting I have some more references on the sense of self, agency, and personal space here and here.

3 Likes

#3

I hope this is relevant to your ongoing conversation! I just noticed your post and some associations popped into my mind.

The brain maps peripersonal space. Whatever tool you use (a screw driver, a guitar, your car) is actually mapped as if it is you (based on fMRI studies–google “peripersonal”). For example, the brain perceives a blind person’s cane as an actual extension of the arm.

When I taught blind kids to navigate, I had them “probe” space in layers (i.e. move their attention system ever-outward): personal space (peripersonal) is within reach of arms and tools; communication space is interpersonal space just beyond peripersonal (beyond reach); landmark space is further out still, but contains sensory cues that can be used to position a body within a domain. Beacon space contains things like the sun, wind from a specific direction, a morning train whistle, etc)–signals that are outside the immediate vicinity (outside landmark space) but which can be used for orientation.

As part of my Navigational Consciousness theory, I postulated that our brain maps all these layers of space as if they are part of our body. In other words, delineated spatial domains are perceived as objects.

Dual-consciousness itself (using dual-process theory) is derived from proprioception (in my theory). Duality arises because egocentric processing is mutually exclusive with allocentric processing. A good source here are the books of Shaun Gallagher (How the Body Shapes the Mind, for example). Gallagher differentiates “Body Image” which is egocentric from “Body Schema,” which is allocentric.

I am not sure how this fits with “the constructed location signal.”

3 Likes

#4

Good callout on the use of peripersonal space in training.

I see a continuum from internal joint and musculature sensations to the skin to visual sensing of external space. These are all processed in the somatosensory and visual (and auditory) cortex to the parietal lobe. I see that as the fusion of the various experiences into a unitary whole that is passed on to the temporal lobe as your experienced reality.

Successful use of a prosthetic requires the user to “extend” a phantom into the appliance. Page 106:

This can be useful in patients with a strong phantom limb presence.


https://www.hortonsoandp.com/manage-phantom-limb-pain-prosthesis/

Kind of geeky but I like it when tech helps:

When you watch a skilled backhoe operator it is clear that the controls have melted away and the man has extended his agency into the machine.

3 Likes

#5

Much of HTM theory requires that the sensed pattern is at some location in space. Depending on which Numenta paper you are reading there is considerable variation is specific details; in some of the papers it “just is” with with faith that it will be sorted out later.

I offer this thread as an attempt to fill in these details.

As far as splitting out ego/allo centric coding I see this as representations at different cortex maps. At the maps closest to the central sulcus - egocentric, V1, retino-contric, Auditory is special as stereo phase coding in S1 does give egocentric coding as an extracted property.

Areas after sensory fusion with the vestibular system in the medial temporal lobe, clearly allocentric.

0 Likes

#6

I have heard @jhawkins say that the extra layer(s) in L4 within visual cortex (V1?) might be a place where this allo / ego translation is occurring.

0 Likes

#7

Matt,
The first two posts in this thread show the “place” where this happens.

1 Like