Chapter 5: The ‘Other’ Sensory Systems

Audition: Hearing1. What is the stimulus in the auditory

system?

2. Important characteristics of the auditory stimulus:

Frequency = pitch Amplitude (decibels) = volume/

loudness of a sound

Anatomy of the Ear1. Outer Ear

Pinna Auditory canal

2. Middle Ear The tympanic membrane Bones: malleus, incus, & stapes

3. Inner Ear Cochlea

Structures of the Ear

More about the Cochlea

1. The cochlea is fluid filled and is lined with the sensory cells for hearing

2. Down the center of the cochlea runs the Basilar membrane

3. The cells that actually ‘hear’ are called hair cells

4. The hair cells transfer their information to the cells of the auditory nerve

The Cochlea in Detail

Pitch perception in the Ear1. Frequency Theory – says that the basilar

membrane moves in synchrony with the frequency of a sound wave

What do you know about Action Potentials that would make this theory impossible??

2. Place Theory – says that parts of the basilar membrane move like keys on an instrument, just the part of the membrane responsible for a given pitch moves

In Reality… It turns out that we use a

combination of place and frequency:

For tones less than 100 Hz, our APs can keep up with frequency theory

Hair cells at the base of the cochlea, near the oval window respond best to high frequency tones, while hair cells at the apex (middle) of the cochlea respond best to lower tones

Pitch Perception in the Brain 1. Auditory info undergoes cross-over

– what does this mean?

2. The auditory cortex is located in the temporal lobes

Sound location The cortex is tonotropic Brain injury to this part of the brain does not

result in total deafness

Problems with Hearing1. Conductive Deafness

2. Nerve Deafness

3. Tinnitus

Taste1. Taste is made up of 4 basic sensations:

1. Sweet2. Salty3. Bitter

4. Sour

2. Those bumps AREN’T buds!3. Inside each bud are about 50-100 taste

receptors. these receptors replace themselves every couple of weeks

The Tongue

Location of Taste on the tongue

1. Most taste buds are on the edges of the tongue

2. Different parts of the tongue are better at tasting different taste sensations

3. The taste receptors can send different messages to the brain based on prior exposure to certain chemicals

Taste Info in the Brain1. Cranial nerves carry taste info from

the tongue to the brain

2. Thalamus Medulla Limbic system Insular cortex (frontal lobe) = primary taste cortex

3. The brain receives ipsalateral information from the tongue – what does that mean?

Olfaction: Smell1. Olfaction, like taste, is a chemical sense

2. The olfactory membrane holds the receptor cells, the ends of which terminate the olfactory bulb

3. We don’t really know how receptor cells work

4. Smell is very closely related to memory – why might this be? Think location…

Vomeronasal Receptors1. This is the organ through which

animals sense pheromones

2. Pheromones are chemicals that have a distinct effect on other members of our species

3. Can humans sense pheromones? How do we know?

Totally gross research, that’s how.

Vestibular Sense This is our sense of head position

and balance

There are two important structures in the inner ear, next to the cochlea that make up the vestibular organ:

The semicircular canals The otolith organs

Proprioception1. This is our sense of our body’s position in

the world

2. Proprioception happens because of special receptors in our joints• You may have fooled the receptors

before, if not try it with a friend

3. This information is combined with our vestibular sense to help us decide how to move our bodies in a given situation

Somatosensation1. This is our sense of touch, body movement,

and position of our limbs. 2. Touch includes:

Temperature Pain Pressure Itch Tickle

3. There are at least 7 kinds of touch receptors in your skin – I want you to know 2:

Pacinian Corpuscles Meissner’s Corpuscles

How does Touch Info get to the Brain?

1. From the head up, touch info enters via the cranial nerves, from below the head via the spinal cord

The cord has distinct pathways for different kinds of touch information

2. Once in the brain, the info stops at the…, then heads to the somatosenory cortex in the…. (you guys know this!!)

Pain

1. There are different kinds of neurotransmitters for different kinds of pain

Glutamate Substance P

2. Endogenous opiates (endorphins)

Gate-Control Theory of Pain1. This theory says that the spinal

cord actually makes ‘decisions’ about what pain information gets up to the brain

2. Endorphin release in the midbrain causes the brainstem to inhibit release of substance P

The blurred line between Somatosensory Sense and

Chemical Sense

1. Our ability to detect painful heat can be evoked by application of a chemical called capsaicin

2. How can exposure to capsaicin actually make you feel less pain?

The Psychology of Pain1. Circumstantial influence

1. Pain thresholds

2. Pain is ADAPTIVE

Pain Control While we still don’t totally

understand the mechanisms of pain sensation and perception, pain control is a huge area of research

Techniques range from physical intervention to psychological techniques

What the heck is an itch, anyhow?

1. An itch is a sensation on the skin created by histamine release

2. Pain and itch inhibit each other

3. Itch sensations are also adaptive

Sensory Interaction This is the idea that the sensory

organs can influence each other. Can anyone give me an example?

The best example I can think of is the influence of…

Attention?1. Why are we talking about attention

in the sensory chapter and not in the consciousness chapter?

2. Does our brain activity change when we are attending to a given stimulus?

Selective Attention1. Selective attention is our ability to

focus on one thing and ignore pretty much everything else.• Selective attention is what we

‘choose’ to attend to.

2. This is a very important, adaptive skill

Neglect

1. Neglect is the opposite of attention

2. Brain damage often causes a non-voluntary, specific neglect

Spatial neglect

Attention Deficit Disorder1. People with ADD or ADHD exhibit

high levels of distractibility, hyperactivity, impulsivity, poor control of anger, etc.

2. Is this a true mental disorder or a social phenomenon?

Testing for ADD/ADHD1. Choice-delay task

2. Stop Signal task

3. Attentional blink task

Brain Differences?1. ADHD does run in families

2. May be a dopamine receptor problem

3. Smaller overall brains, with specific size differences in the right prefrontal cortex & cerebellum

4. Too much slow-wave activity

Treatments1. Stimulant drugs are often prescribed

2. Brainwave biofeedback might help

3. There are behavioral techniques that can help: