Sensation & Perception: Touch

13 flashcards · Biology · by lakesare

1. Name 3 parts of the somatosensory system.

   cutaneous senses - ability to sense touch, pain. proprioception - ability to sense the position of the body and limbs. kinesthesis - ability to sense the movement of the body and limbs.

2. Name 2 layers of the skin.

   Epidermis - layer of dead skin cells Dermis Our main experience with the skin is its visible surface, which is actually a layer of tough dead skin cells.This layer of dead cells is part of the outer layer of skin, which is called the epidermis. Below the epidermis is another layer, called the dermis.

3. Neurons from retina project into the lateral geniculate nucleus in the thalamus. Neurons from cochlea project into the medial geniculate nucleus in the thalamus. Neurons from skin project into the _______________________ in the thalamus.

   Ventrolateral nucleus Most of these fibers synapse in the ventrolateral nucleus in the thalamus, but some synapse in other thalamic nuclei.

4. To measure vision acuity we use charts. How do we measure tactile acuity?

   two-point threshold - when person starts feeling like it's 1 dot pressing against their skin instead of 2 The minimum separation between two points on the skin that when stimulated is perceived as two points. The two-point threshold is measured by gently touching the skin with two points, such as the points of a drawing compass, and having the person indicate whether he or she feels one point or two.grating acuity - when person stops being able to determine whether it's horizontal or vertical s…

5. What's meant by the receptive field for a neuron in the cutaneous system?

   Receptive field of a neuron in the cutaneous system is the area on the skin that, when stimulated, influences the rate of that neuron. Remember that the receptive field for a neuron in the visual system is the area on the retina that, when stimulated, influences the firing rate of the neuron. The receptive field for a neuron in the cutaneous system is the area on the skin that, when stimulated, influences the firing rate of the neuron.

6. What are these yellow circles? Monkey's hand

   Receptive fields of monkey cortical neurons that fire (a) when the fingers are stimulated; (b) when the hand is stimulated; and (c) when the arm is stimulated. Large receptive fields allow the cell to detect changes over a wider area, but lead to a less precise perception. Thus, the fingers, which require the ability to detect fine detail, have many, densely packed (up to 500 per cubic cm) mechanoreceptors with small receptive fields (around 10 square mm), while the back and legs, for example,…

7. Name 4 mechanoreceptors in the skin.

   Merkel receptors - fine details Meissner corpuscle - handgrip control Ruffini cylinder - stretching Pacinian corpuscle - vibration, fine texture by moving fingers

8. What's duplex theory of texture perception?

   Spatial cues are caused 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. These cues result in feeling different shapes, sizes, and distributions of these surface elements. An example of spatial cues is perceiving a coarse texture such as Braille dots or the texture you feel when you touch the teeth of a comb. Temporal cues occur when the skin moves across a textured su…

9. What's pain matrix?

   Regions of the brain involved in pain processing. Although pain is associated with the overall pattern of firing in the pain matrix, there is also evidence that certain areas in the matrix are responsible for specific components of the pain experience.

10. What's the physical basis behind placebo?

    Pain-reduction effect of placebos occurs because placebos cause the release of endorphins. This finding, along with other evidence, suggests that the pain-reduction effect of placebos occurs because placebos cause the release of endorphins. Because placebos contain no active chemicals, their effects have always been thought to be “psychological.” However, the idea that placebos cause the release of endorphins provides a physiological basis for what had previously been described in strictly psyc…

11. What people can withstand higher levels of pain stimulation?

    Finally, a recent study has identified genetic differences in people that cause their brain to release different amounts of opioids in response to painful stimuli (Zubieta et al., 2003). This study found that people whose brains released more opioids were able to withstand higher levels of pain stimulation.

12. Two types of pain?

    A-delta fibers - first pain C-fibers - second pain (my throbbing pain) In the 2nd - some of these pathways influence our overall level of attention, arousal.

13. What's hyperalgesia?

    Hyperalgesia - is an abnormally increased sensitivity to pain, which may be caused by damage to nociceptors or peripheral nerves and can cause hypersensitivity to stimulus.