Readings for Lecture 24, 25, and 26

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What is effortful or dynamic touch?
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Terms in this set (45)
What is proprioception?Sense of body position and movement.What provides information about the position of limbs?Orientation of the inertial ellipsoid.What is a tensegrity structure?A structure in which inflexible components are flexibly held together by elastic tension.What kind of structure is the human skeleton?Biotensegrity structure.The touch system is a _____ system.Continuous.Why can objects not have the same mass but feel similarly heavy?They have similar shapes, this makes perceiving the affordances for the object in motion similar.What makes up the somatosensory systems?1. The Cutaneous Senses 2. Proprioception 3. KinesthesisWhat are the layers of the skin?1. Epidermis 2. Dermis 3. HypodermisWhat within the skin responds to mechanical stimulation such as pressure, stretching, and vibration?Mechanoreceptors.What two receptors are located close to the surface of the skin?Merkel receptor and Meissner corpuscle. They have small receptive fields since they are so close to the surface.What is a cutaneous receptive field?The area of skin which, when stimulated, influences the firing of the neuron.When do Meissner corpuscles fire?Fires only when a stimulus is first applied and when it is removed. They are called rapidly adapting (RA1) fiber.When do Merkel receptors fire?Continously as long as the stimulus is on. They are called slowly adapting (SA1) fiber.What does the case of Ian Waterman demonstrate?Touch receptors are widely distributed and unique, working together to fully use the sense of touch. Ian Waterman lose his ability to feel touch and sense the position of his limbs (medial lemniscal pathway) but could still sense pain and temperature (spinothalamic pathway). These pathways work similar to visual receptor information meeting in the LGN.What is the lemniscal pathway?Pathway that have large fibers that carry signals relating to touch and proprioception.What is the spinothalamic pathway?Pathway that carry info mainly about pain, itch, temperature and crude (non-discriminative touch and pressure).What are the two areas that receive information from the thalamus?The primary somatosensory cortex (S1) and the secondary somatosensory cortex (S2).Similar to how vision is spatially mapped out in the brain, so is touch, what is the resulting body map called?Homunculus.Similar to how the fovea has a disproportionate area on visual mapping due to it's information intake, which part of the body is disproportionately mapped for touch?Things that detect details through touch, such as the fingertips.What perceptual skill do things like reading braille rely on?Tactile acuity. This is measured by the two-point threshold.What is greater tactile acuity associated with?Less spacing between Merkel receptors.What receptor is responsible for sensing vibration?Pacinian corpuscle. It has layers like an onion, with fluid between each later to respond to rapid changes in pressure.What is surface texture?Physical texture of a surface created by peaks and valleys.What is the Duplex Theory of Texture Perception (Katz)?States that our perception of texture depends on both spatial cues and temporal cues. Recent research has shown we use more spatial cues than anything.What are spatial cues?Provided by relatively large surface elements, such as bumps and grooves, that can be felt both when the skin moves across the surface elements and when it is pressed onto the elements.What are temporal cues?Cues that occur when the skin moves across a textured surface like fine sandpaper. This type of cue provides information in the form of vibrations that occur as a result of the movement over the surface.What responds to texture?The SA1 and PC receptors.What is active touch?The perception of objects through manipulation/exploring with touch. Active touch includes passive touch.What is passive touch?No Pressure or motion, like a hand rests on animal or the two-point test.What is haptic perception?The active exploration of the environment by touching and grasping objects with our hands.What systems are engaged with haptic perception/active touch?1. The sensory system, detecting cutaneous. 2. The motor system, involved in moving hands and fingers. 3. The cognitive system, using in organizing/interpreting information provided by the previous system.What are CT afferents?C-Tactile fibers, unmyelinated, and located on hairy skin.What is the social touch hypothesis?CT afferents and their central projections are responsible touch.What are the discriminative functions of touch?Using touch to sense details, texture, vibration, and objects.What is the affective function of touch?Sensing pleasure and therefore often eliciting positive emotions. The CT system is the basis for this form of touch.