Week 3A: Vestibular system, somatonsensation and the chemical senses

Somatosensory system registers

Touch

Vestibular system registers

Balance

Balance: The sensory receptors of the vestibular system are located in (…) ear (Outer, middle, inner)

Inner

Damage of sensory receptors of the vestibular system cause

Imbalance, nausea

Balance: What do otolith organs register

Linear acceleration and gravitation

Balance: What do semicircular canals do

Angular acceleration and one canal for rotation axis

Main functions of the vestibular system

Balance, stabilise retinal image and compensate for head movements

Balance: Each receptor consists of one tall thick hair, called the (…), flanked on one side by a group of thinner hairs, tapering in height, known as (…)

Kinocilium, stereocilia

Balance: What happens when the head moves counterclockwise?

• Fluid moves (…) relative to the head

• Haircells bend (…)

• Left lateral rectus is (…)

• Right lateral rectus is (…)

• Opposite pattern for medial recti

• Eyes move (…)

Clockwise, right, inhibited, excited, clockwise

Balance: What is motion sickness

Cue conflict between vestibular and visual senses

Balance: Oculogyral illusion and Coriolis effects

Dizziness from body rotation. When you stop spinning fluid in the semi-circular canals start moving

Balance: Oculogravic illusion

Illusory tilt percept during linear acceleration

Balance: Vection

Sensation of self-motion

Balance: The vestibular organ includes (…) canals and (…) sacs; each contains fluid or gel and a pathc of sensory ahir activitaded by fluid or gel displacement

3, 2

Balance: Rotational acceleration of the head activitates (…) in the canals

Receptors

Balance: Linear acceleration and head tilt activate (…) in the sacs

Otolith receptors

Balance: Two types of otolith receptors in the sacs

Utricle and saccule

Balance: The vestibular system does not encode (…) speed

Constant

Our oldest and most primitve sense

Touch

Touch is a (…) sense, we feel things close to us or that actually contact us

Proximal

Touch: Nociception registers

Pain, temperature and tickle

Touch: Proprioception registers

Information about position of body parts

Touch: Kinesthesis registers

Information about movement of the body parts

Touch: Risk of being unable to touch

Impared manipulation of objects and walking

Touch: Risk of being unable to feel pain

Risk of infections due to unattended injuries (leprosy)

Touch: Risk of being unable to sense proprioception and kinesthesis

Relearn walking and only visually guided motion

Skin: area

1.8 cubed meters

Skin: Pacinian corpuscle function

Fast changes

Skin: Meissner corpuscles function

Touch

Skin: Merkle discs function

Touch and pressure

Skin: Ruffini end organs function

Touch pressure, joint angulation

Skin: Nociceptors function

Pain, temperature and tickle

Skin: pacinian corpuscles function

Pressure and vibration

Skin: Ruffini’s corpuscles function

Stretching of skin

Muscle spindles

Muscle length

Gogli tendon organs function

Muscle tension

Difference slowly and rapidly adapting

First a few spikes, then spikes in timely order vs. few quick spikes and no spikes after that

Meissner corpuscles: (…) receptive fields (small or large)

Small

Pacinian and ruffini corpuscles and end organs: (…) receptive organs

Large

Senses: 1, 2, 3, 4, 5

Vision, Touch, Hearing, Taste, Smell

How do we find sensitivity on the skin

Tactual acuity: Two point thresholds

Where is the skin the most sensitive

Hands and face

Haptic perception definition

Sense an object’s properties through touch, proprioception and kinesthesis

Why is it hard to recognise 2D raised line drawings

The world is 3d and we perceive the world as 3d. Our haptic system is not trained in this.

Why is it easier to recognise a drawing by visual instead of by touch (if there were ridges to touch)

Visual: Fits entirely in your field of attention
Touch: temporal build up of information that you have to store.

Curvature aftereffect

After touching a convex shape for 10 seconds, a flat shape feels concave

Meaning veridical

Coinciding with reality

Why is our sense of smell blunted when we have a cold

Build-up of mucus in the nasal cavity that prevents odor molecules reaching the receptor cilia

Why can people smell less during or after covid

Brain damage

How do we smell

Molecules bind with receptor sites on the cilia

How long do odor receptors live

60 days

Detection

• Airborne moleculs dissolve in the (…) mucus

• Moleculs bind with receptor sites on the (…)

• This results in a change in membrane potential

• Mitral cells project to the (…) and the (…)

Olfactory, cilia, primary olfactory cortex, amygdala

What is population coding

Limited number of receptor types can detect many different smells by activating in various patterns

Odor adaptation is much stronger for (…)-adaptation than for (…)-adaptation

Self, cross

The perceived intensity of a smell drops to (…)% after (…) minutes of exposure

30, 12

Taste bud cells live about (…) days

10

5 basic tastes

bitter, salty, sweet, umami, sour

Cross-adaptation to taste

Adaptation to one sour taste will cause water to taste sweet

Taste: Labeled-line theory

Argues that each fiber codes the intensity of a single taste dimension

Taste: Cross-fiber theory

Taste quality is coded by the pattern of activity across all fibers

Cross-fiber theory

This theory suggests that the brain interprets sensory information by analyzing the pattern of activity across a group of nerve fibers

If a food induces illness, many animals later show a strong aversion to the food. The effect (…) be overruled by knowledge (can or cannot)

Cannot

Balance: 1 and 2

Otolithic membrane, otoconia

Balance: 1,2,3,4

Semicircular canal, ampulia, cupula, hair cells

Balance: The rate of (…) release from the base of the cell depends on the direction of hair cell (…), and affects spike activity in the (…) nerve

Neurotransmitter, displacement, efferent

Skin: 1, 2, 3, 4, 5, 6

Fat globules, end bulbs of Krause, Sebaceous gland, Meissner’s corpuscle, Merkle discs, Ruffini ending, Pacinian corpuscle

1, 2

Merkle Ruffini, Pacinian Meissner