bodily senses

What do the somatosenses provide information about?

The body’s surface and internal state.

What are cutaneous senses?

Senses that respond to stimulation of the skin.

Which stimuli do cutaneous receptors detect?

Pressure, vibration, temperature change, and tissue damage.

What type of receptor detects pressure and vibration?

Mechanoreceptors.

What is glabrous skin?

Skin without hair (e.g., palms and fingertips) with dense receptor concentration.

Why does glabrous skin have many receptors?

It is used for active exploration of the environment.

What are the three layers of the skin?

Epidermis, dermis, subcutaneous tissue.

What is proprioception?

Sense of body position.

What is kinesthesia?

Sense of body movement.

Which receptors contribute to proprioception?

Skin stretch receptors, muscle stretch receptors, and joint receptors.

What do muscle stretch receptors detect?

Changes in muscle length.

What do joint receptors detect?

Magnitude and direction of limb movement.

What are organic senses?

Sensations arising from internal organs.

Give an example of a conscious organic sensation.

stommy horty

What is tactile stimulation?

Pressure or vibration changes against the skin.

How does somatosensation interact with the motor system?

It provides feedback during active exploration.

What was observed in violinists regarding somatosensory cortex?

Larger representation of the used hand.

What type of neural plasticity does this demonstrate?

Experience-dependent cortical reorganisation.

Where are cold receptors located?

Just beneath the epidermis.

Where are warmth receptors located?

Deeper in the skin.

Are warmth and cool sensations absolute or relative?

Relative.

What is temperature adaptation?

Reduced sensitivity after prolonged exposure to heat or cold.

How does heat affect warmth receptors?

Decreases sensitivity.

How does cooling affect cold receptors?

Decreases sensitivity after adaptation.

What chemical produces a cool sensation?

Menthol.

What chemical produces a burning heat sensation?

Capsaicin.

What receptors detect pain?

Nociceptors.

What are high-threshold mechanoreceptors?

Free nerve endings responding to intense pressure.

What stimuli activate nociceptors?

Extreme heat, acids, capsaicin, intense mechanical pressure.

Why does scratching reduce itch?

Pain fibres inhibit itch signals at the spinal cord.

What are the three components of pain?

Sensory, immediate emotional, and long-term emotional components.

Which brain region processes the sensory component of pain?

Primary somatosensory cortex.

Does hypnotic suggestion reduce activation in primary somatosensory cortex?

No, it affects unpleasantness but not sensory activation.

What does this show about pain processing?

Sensory and emotional components are separable.

What is analgesia?

Reduction in pain perception.

How can interneurons reduce pain transmission?

They inhibit pain projection neurons in the spinal cord.

Which pathway transmits fine touch?

Dorsal column–medial lemniscus pathway.

Which pathway transmits pain and temperature?

Spinothalamic pathway.

How is the somatosensory cortex organised?

In columns and multiple body maps.

What do neurons within a cortical column respond to?

A specific stimulus type from a specific body region.

How many primary taste qualities are there?

Six.

What are the six taste qualities?

Sweet, sour, salty, bitter, umami, and fat.

What is flavour?

Combination of taste and smell.

Where are taste receptors located?

In taste buds on papillae of the tongue.

What are papillae?

Small protrusions on the tongue containing taste buds.

Through what do gustatory signals travel from the tongue?

Cranial nerves.

Where do taste-sensitive neurons project before cortex?

The thalamus.

Where is the primary gustatory cortex located?

Base of frontal cortex and insular cortex.

Is taste represented ipsilaterally or contralaterally?

Ipsilaterally.

What does ipsilateral representation mean?

Right tongue projects to right brain, left to left.

What other inputs does gustatory cortex receive?

Thermal, mechanical, visceral, and nociceptive input.

Where is the olfactory mucosa located?

Top of the nasal cavity.

What percentage of inhaled air reaches the olfactory mucosa?

Less than 10%.

What must odorant molecules do before receptor activation?

Dissolve in mucus.

Where do olfactory receptor neurons project first?

Olfactory bulb.

Where do olfactory tract axons project directly?

Amygdala, piriform cortex, and entorhinal cortex.

What is the primary olfactory cortex?

Piriform cortex.

Does olfaction relay through the thalamus before cortex?

No.

Approximately how many odour receptor types do humans have?

339.

How can humans detect over 10,000 odours with 339 receptors?

Combinatorial coding patterns of receptor activation.

What determines a specific odour perception?

Unique combination of activated receptors.

What is anosmia?

Loss of smell.

What may cause COVID-19 related anosmia?

Inflammation of olfactory clefts or epithelial/central damage.

What is the placebo effect?

Brain–body response due to belief in treatment.

Are placebos physiologically active substances?

No, they are inert.

Can placebos still produce measurable effects?

Yes.

What neurotransmitter system is activated in placebo analgesia?

Endogenous opioid system.

What imaging method showed opioid binding after placebo?

PET imaging.

How did price perception affect placebo pain reduction?

Higher perceived price increased reported pain reduction.

What does this demonstrate about placebo effects?

Context influences brain responses.

Which somatosensory information is precisely localised?

Fine touch.

Which somatosensory information is poorly localised?

Pain and temperature.

What principle explains itch suppression by pain?

Gate control at the spinal cord.

What type of receptors detect mechanical skin deformation?

Mechanoreceptors.

What type of receptors detect temperature?

Free nerve endings (thermal receptors).

What type of receptors detect tissue damage?

Nociceptors.

What overall principle applies to all sensory systems in this lecture?

Different receptor types send information via specific pathways to specific cortical regions.