touch

Touch receptors

Detect pressure

Brain area for touch

Parietal lobe (somatosensory cortex).

Where touch info is processed

Somatosensory strip in parietal lobe.

Body areas with many touch receptors

Tongue

How sensations combine

Brain can merge signals (e.g.

Misperceptions of touch

Occur when the brain combines signals incorrectly.

Example of shared receptors

Cool and mint share the same sensory pathway.

Social and physical warmth

Share overlapping brain regions and receptors.

Expectations and touch

Expectations alter sensations (touch from boyfriend feels different than from friend).

Power of touch

Touch can affect emotion

Harlow’s monkey study

Showed infants prefer comfort (softness) over food.

Touch and infants

Touch promotes physical growth and mental health (preemies gain weight faster).

Touch and immunity

Massage therapy boosts immune function (e.g.

Maternal licking in mammals

Helps offspring breathe

Human examples of touch effects

Waitresses who touch receive bigger tips; touched librarians rated more favorably.

Sex therapy focus

Emphasizes touch over intercourse to increase intimacy.

Value of pain

Serves as a defense mechanism to signal injury or danger.

When pain begins developmentally

Fetuses feel pain before birth.

Humans without pain

Tend to die young because they can’t detect injury.

Beneficial pain

Some pain (e.g.

Referred sensation

Pain felt in a different area from its source (e.g.

Examples of referred pain

Kidney = back pain; heart = left arm; stroke = right arm.

Pain theory purpose

Pain makes you slow down and pay attention to injury.

Substance P

A neurotransmitter that transmits pain signals in the nervous system.

Two pain pathways

Sharp (fast) and dull (slow) pathways.

Sharp pain

Immediate “stabbed” feeling — travels faster.

Dull pain

Longer

Capsaicin

Depletes substance P and produces a burning sensation followed by pain relief.

Why hot peppers feel hot

They activate heat-sensitive pain receptors.

Absence of pain after large pain

Occurs when substance P is depleted (temporary relief).

Pathway of pain in brain

Pain signals travel from spinal cord to somatosensory cortex and cingulate cortex.

Role of somatosensory cortex

Processes location and intensity of pain.

Role of cingulate cortex

Processes emotional aspect of pain.

Cortex and pain

Pain can occur even without a cortex (as shown in mammals).

Connection between emotional and physical pain

Both activate similar brain areas and occur together.

Why placebos work

They alter brain expectation and reduce perceived pain.

Cingulate cortex in emotion

Also activated during social rejection or spending money.

Social vs physical pain

Social pain is easier to recall and more enduring.

Gender differences in pain

Women show quicker emotional responses to pain.

Pain threshold

The point at which a stimulus is first perceived as painful (biological measure).

Pain tolerance

How much pain one can endure (psychological measure).

Mood and context effects on pain

Mood

Anxious individuals and pain

Experience more pain because of heightened arousal.

Older adults and pain

Experience less pain due to adaptation over time.

Pain medications

Over-the-counter drugs block some pain signals; strong opioids block nearly all.

Gender differences in help-seeking

Women detect pain and seek help faster than men (could be social or biological).

Context and perception of pain

Pain often noticed only after adrenaline drops (e.g.

Timing and memory of pain

People remember the peak and end of pain more than duration.

Empathy and pain

Seeing someone in pain activates similar brain areas as feeling it yourself.

Mirror neurons and empathy

Fire both when feeling pain and when observing pain.

Endorphins

Brain’s natural painkillers that block substance P release.

When endorphins work

Effective on dull

Runner’s high

Feeling of euphoria after exercise due to endorphin release.

Acupuncture and endorphins

Needle stimulation triggers endorphin release for pain relief.

Genetic differences in endorphins

Some people naturally produce more or fewer endorphins.

Injury and sodium gates

Injury opens sodium channels in receptors

Why injured areas feel more sensitive

Sodium gates make nearby neurons easier to fire.

Capsaicin and heat link

Causes heat sensation because it opens heat-sensitive channels.

Histamine release after injury

Triggers itching and swelling as a defense response.

Histamines and allergies

Help fight allergens but also cause inflammation.

Histamines and sleepiness

Blocking histamines causes drowsiness (in antihistamines).

Endorphins vs sharp pain

Endorphins don’t affect sharp pain because it travels on faster nerve fibers.