Chapter 8: General Principles of Sensory Processing, Touch and Pain

Sensation

The process of how we experience sensations from sensory input

Ex: touch, sight, sound, taste

Perception

The process by which our brain interprets sensory info, lets us recognize objects

Ex: how we discern a hug from a punch, a burn from a stove from cold from snow

Transduction

How sensory system convert one form of energy into another

Ex: vision processes light waves, hearing processes sound waves

Attention

Key part of transduction

Process by which we focus on stimuli

Posterior Parietal Lobe

Activates with attention

All sense

Cingulate Cortex

Activates with attention

Directs attention to stimulus

All senses

Tectum

Activates with attention

Superior = visual

Inferior = auditory

Sensory Interaction

One sense can influence the other, blending inputs

Ex: smell and taste, sight and sound

Synesthesia

People see colors for numbers etc.

Ex: 2 is red, 5 is green

Epidermis

Outer layer of skin

Thinnest layer

Dermis

Middle layer of skin

Contains blood vessels

Subcutaneous

Inner layer of skin

Shapes body

Pacinian Corpuscle

Vibration receptors

Large, vague borders

Fast adapting

Meissner’s Corpuscle

Light touch receptors

Small, sharp borders

Fast adapting

Merkel’s Discs

Fine touch receptors - pin point spots on body

Small, sharp borders

Slow adapting

Ruffini’s Ending

Stretch receptors - think stretching in the morning

Large, vague borders

Slow adapting

Somatosensory Cortex (size + space)

The more sensitive a body part, the more space it takes up in the somatosensory cortex

Primary Somatosensory Pathway

1. Skin

2. Unipolar neurons transport sensory info to dorsal root of spinal cord

3. Spinal cord carries to brain stem (medulla oblongata)

4. Medulla oblongata sends sense to thalamus

5. Thalamus carries to high sensory cortex

Psychology of Touch

Touch aids our development

Touch therapy can help low weight babies grow

Nociceptors

Carry pain information

Pain Receptor Pathways

1. Tissue injury

2. Nociceptor gets pain sensory information

3. Nociceptor sends message to nerve cell

4. Sensory sent to spinal cord

5. Projection sent to brain to move limb from pain

What controls pain response?

Thalamus

Singular Cortex

Itching Pathway

Same as pain receptor pathway

Pain goes to thalamus

Processed by pons

Phantom Limb Pain

Feeling pain in a limb that is no longer there from amputation

Attentional Biases

1. Pain’s peak

2. How much pain was felt at end

Placebos

Fake painkillers

Can control pain

Elicits release of endogenous endorphins

Distraction

Distraction during painful procedure can lessen pain activity in brain

Can control pain

Hypnosis

People can withstand more pain when hypnotized

Can control pain

Social Pain and Physical Pain

Both cause increased activation in the anterior cingulate cortex

Pain killers are effective at numbing both kinds of pain