Project notes

Preliminaries: Place fields / spatial representation

Consider:

  • Spatially selective neteorks
    • place cells
    • grid cells
    • border cells
    • rate remapping / cues
  • Alistair's ideas
    • Gibson (1950) cognitive representations of objects built on surfaces
    • stable support (Haggard 2013)
    • slip (Adams 2013)
  • Martin's locomotion / trajectory based spatial learner MSOM
    • MSOMs (Strickert 2005)
    • SOMs (Kohonen 1982) *Centrality of physical exploration in representing spatial properties
    • Surface reps activated by both vision and touch? (Lacey 2009)
    • Inability to visually identify unseen objects learned through touch
    • Theories of visual learnign mediated via touch exploration?
    • Objects in space vs object-independent space representations

Background 0: Ali's Vision

"basic concept of surface is due to a primitive sensorimotor concept called the stable contact signal" (Ideas 3.3.1)

"For many SII cells, receptive fields are better described in relation to peripersonal space than to body parts, because they respond to contact on several different body parts. For instance, there are SII cells that respond to touches by several different fingers (see e.g. Fitzgerald et al., 2006), or even to touches by both hands (see e.g. Iwamura et al., 2001). In these cases, the fingers are often aligned within a single plane in the hand (see e.g. Fitzgerald et al., 2006). A conclusion drawn by several researchers, and well summarised by Haggard (2006), is that SII cells compute representations of surfaces in the observer’s peripersonal space. These representations can be thought of as representations of stable contact or stable support in the somatosensory system." (3.3.3)

"The axis parallel with the fingers provides a natural ‘forward/back’ axis, with ‘forward’ being the direction in which the fingers point. The axis perpendicular to the fingers provides a natural ‘left/right’ axis." 'Up' as the direction that breaks stable contact? (3.3.3.1.1)

"The key idea in my learning model is that the stable support signal is intrinsically re-warding, at least in developing infants: in other words that it is hard-wired by evolution to generate a reward signal in the motor system. This means that infants are drawn to learn how to achieve stable support states, and consequently, to learn functions mapping percep-tual representations of objects in their peripersonal space onto goal motor states associated with the stable support signal. These are at the origin of our perceptual representations of the surfaces of objects." (3.3.5)

"analogous to the environments in which the observer moves—except objects are environments that are navigated in by the observer’s effector" (Ideas 3.9.1)

"I propose that the shape of an object is represented in exactly the same format as a navigation environment: as an allocentric boundary structure," (3.9.2)

"Hamada and Suzuki (2005) found representations of simultaneous con-tact by the index finger and thumb which varied when the angle between these digits was changed" (3.9.4.1)

"Object-centred neglect is defined in a frame of reference centred on the object being perceived, rather than on the observer or the environment. Typically, neglect is expressed in relation to one of the object’s major axes (see e.g. Driver et al., 1994). The key behavioural test for this type of neglect is that the area of an object which is ignored remains the same if the object is rotated in relation to the observer "Chafee et al. (2007) gave monkeys a task in which a block had to be moved into a shape to complete it; they found neurons in parietal cortex (area 7a) which were sensitive to the block’s position in relation to the object, even when the retinal location of the block varied from trial to trial. These findings argue for a medium in the brain, strongly recruiting parietal cortex, that represents a map of ‘locations within a given object’, that is somehow specified in a coordinate system centred on that object" (3.9.5.1)

"Two squares of different sizes are both squares, but the motor actions needed to interact with them haptically are very different; so there should be a size component" (3.9.5.1)

"A common way to identify the shape of a surface is to navigate systematically around its perimeter (see e.g. Lederman and Klatsky, 1993)." (3.9.5.3)