Chapter 12 The Body Senses

the ability to recognize touch sensation; Perception that results from the mechanical deformationóindentation, vibration, or stretching of the skin.

Sensory receptors that transduce mechanical deformations of the skin into neural signals that are sent to the brain.

Slow-adapting mechanoreceptors with Merkel cell endings; they have relatively small receptive fields and are relatively densely arranged near the surface of the skin.

Slow-adapting mechanoreceptors; they have relatively large receptive fields and are relatively sparsely distributed relatively deeply in the skin.

Fast-adapting mechanoreceptors with Meissner corpuscle endings; they have relatively small receptive fields and are relatively densely arranged near the surface of the skin.

Fast-adapting mechanoreceptors with Pacinian corpuscle endings; they have relatively large receptive fields and are relatively sparsely distributed relatively deeply in the skin.

Specialized endings of SAI mechanoreceptors, where transduction takes place.

Specialized endings of FAI mechanoreceptors, where transduction takes place.

Specialized endings of FAII mechanoreceptors, where transduction takes place.

results from mechanical deformation of the skin

transduce skin deformations into neural signals sent to the brain

The two categories of the 4 main types of mechanoreceptors

The two kinds of slow acting mechanoreceptors

The two kinds of fast acting mechnoreceptors

support detailed perception of spatial patterns, textures, and surface curvatures; have small receptive fields

support the perception of hand conformation; have large receptive fields

support the perception of slip across the skin and maintenance of grip control; have small receptive fields

support the perception of fine textures through transmitted vibration; have large receptive fields

support perception of pleasant or pleasurable skin stimulation

Name the type of mechanoreceptor that has the following characteristics: -Specialized ending: Merkel cell -Position in skin layers: Upper dermis -Density of distribution: relatively dense, especially in fingertips -spatial resolution: high -sensitivity to temporal variation: low -skin deformation that elicits strongest response: indentation by edges, curves, and textures -functions supported: perceiving pattern, texture, and shape -timing of response: spikes at the beginning of deformation then decreases to a plateau (during the middle time); the firing rate decreases back to baseline at the end of deformation; slower firing rate response than FAI and FAII (widest firing rate curve)

Name the type of mechanoreceptor that has the following characteristics: -Specialized ending: unknown -Position in skin layers: Dermis -Density of distribution: relatively sparse -spatial resolution: low -sensitivity to temporal variation: low -skin deformation that elicits strongest response:stretch -functions supported: perceiving skin stretch and hand conformation -timing of response: spikes at the beginning of deformation then decreases to a plateau (during the middle time); the firing rate decreases back to baseline at the end of deformation; slower firing rate response than FAI and FAII (widest firing rate curve)

Name the type of mechanoreceptor that has the following characteristics: -Specialized ending: Meissner Corpuscle -Position in skin layers: Upper dermis -Density of distribution: relatively dense, especially in fingertips -spatial resolution: high -sensitivity to temporal variation: medium -skin deformation that elicits strongest response: motion and low frequency vibration -functions supported: perceiving slip; maintaining grip control -timing of response: firing rate spikes and drops rapidly ; The spike is high and though it is fast acting it is not the fastest (narrow curve)

Name the type of mechanoreceptor that has the following characteristics: -Specialized ending: Pacinian Corpuscle -Position in skin layers: Lower Dermis -Density of distribution: relatively sparse -spatial resolution: low -sensitivity to temporal variation: high -skin deformation that elicits strongest response: high-frequency vibration (ex: Very fine sand paper) -functions supported: perceiving fine textures though transmitted vibration -timing of response: firing rate spikes and drops rapidly ; The spike is not very high compared to all the other mechanorecptors but it is has the most rapid firing rate response (most narrow curve)

Two types of skin

mechanoreceptors within hairy skin, Nerve fibers that entwine each follicle and respond to hair movements., The receptors most likely to detect an ant crawling on your back are ___.

nerve fibers without specialized endings; mediate perception of pain and temperature, tend to be located very near the surface of the skin in the epidermis and upper dermis; Class of receptors that respond to temp, pain, itch, and hair follicle movement; Neuron endings that lack specialized structures on them and that detect cutaneous pain and changes in temperature; Simplest of all receptors that have little specificity so they can be stimulated by different types of stimuli.

Use calipers to test the ability of the subject to differentiate two distinct sensations when the skin is touched simultaneously at two points; fingertip is most sensitive, back of neck is least sensitive ***caliper= an instrument for measuring external or internal dimensions, having two hinged legs resembling a pair of compasses and in-turned or out-turned points

The person is touched on various parts of the body with two pointed probes a small distance apart. The two point threshold is the minimum distance at which the person can judge correctly ____% of the time that tow distinct locations are being touched. Two-point thresholds are similar for males and females and for the left and right sides of the body

In the two-point threshold experiment, the ______ and palm are the most sensitive to the distance between the calipers and the ___ and upper arm are the least sensitive parts of the body during this experiment. ______ fibers are responsible for the perception of two-point thresholds.

show how the pattern of action potential produced by an individual SAI fiber matched up with the pattern of action potentials produced by the entire pattern of the stimulus

Experiment Reponse of an ___ fiber to a Braille-like Pattern: A braille like-pattern of bumps embossed on a plastic cylinder was passed repeatedly across a monkey’s fingertip while the response of a single ___ fiber (fine pattern, texture, and shape receptors) was recorded. Before each new the pass, the pattern was moved down 0.22mm. The spatial event plot shows that the pattern of spikes produced by the fiber closely _____ the pattern of bumps.

Experiment-Responses of Four mechanoreceptor Types to the Same Braille Patterns: The spatial event plots from these human mechanoreceptor fibers show that only the response of the ___ fiber provide a precise representation the stimulus pattern while the other 3 (SAII, FAI, FAII) show an increasingly more ambiguous pattern respectively.

gives insight into the models prediction with respect to the models performance on two measures and their frequency. It shows how many times the predictions were accurate and how many times they were WRONG ***In the Behavioral and Neural Response to Embossed Letters of the Alphabet experiment: showed often people confused each stimulus letter with every other letter—-> in this experiment A was received as A 71% of the time, as B 1% of the time, and as K 3% of the time The experiment demonstrates the functioning of the SAI mechanorecepotors

Which of the 4 main types of mechanoreceptors are slow adapting, and which are fast adapting?

Which of the 4 main types of mechanoreceptors have large receptive fields, which have relatively small receptive fields?

Which of the 4 main types of mechanoreceptors have large receptive fields, which have relatively small receptive fields?

Which of the 4 main types of mechanoreceptors have large receptive fields, which have relatively small receptive fields?