Sensory System

Question 1

What are the principles of sensory system function?

Answer 1

Sensory receptors
receptors are energy filters
receptive fields

Question 2

Sensory receptors general function

Answer 2

specialized cells that transduce or convert sensory energy into neural activity. All the sensory receptors connect to the cortex through a sequence of intervening relay neurons.

Question 3

Receptive fields

Answer 3

specific part of the world to which a sensory receptor responds.
provides a unique view of the world for each sensory system.
Helps to locate sensory events in space.

Question 4

Receptors as energy filters

Answer 4

response only to a narrow band of energy (within each modality energy spectrum)

Question 5

What is the basic organization of sensory system?

Answer 5

After transduction, sensory information is encoded by action potentials.
A present stimulus is encoded by increase or decrease in the discharge rate of the neuron.
The amount of increase can encode the stimulus intensity.
Qualitative changes are encoded by activity in different neurons, or activity in the same neuron.

Question 6

What are the main sensory pathways?

Answer 6

Dorsal pathway/stream it is the where stream.

Ventral pathway/stream it is the what stream.

Question 7

Which sensory system does not relay through the thalamus?

Answer 7

Olfactory (Smell)

Question 8

What do sensory system subsystems do?

Answer 8

Perform distinct and specific roles and are independent

Each sensory system has distinct wiring with certain behaviors.

Question 9

What is the role of neural relays

Answer 9

Receptors connect to the cortex through a sequence of three or four intervening neurons.
Relays allow sensory systems to interact
Relays allow sensory systems to produce relevant actions.
Also message modification happens at the neural relays.

Question 10

What is the process of energy transduction in vision?

Answer 10

light is converted to chemical energy in the photoreceptors, and this is converted into action potentials.

Question 11

What are the photoreceptors and their location and functioning?

Answer 11

Rods: sensitive to dim light, night vision. Located in the peripheral retina.
Cones: Sensitive to bright light, day vision and color vision. Densely packed in the fovea

Question 12

What is color-deficient?

Answer 12

People who lack one or more types of photoreceptors for parts of the usual visual spectrum.

Question 13

Anatomy of the eye and visual processes

Answer 13

Ray of light enter the eye through the cornea, which bends them slightly, then go through the lens, which bends them to a much greater degree to focus the visual image, upside down and backwards, on the receptors at the back of the eye. Many of the fibers forming the optic nerve bend away from the retina’s central part of fovea, so as not to interfere with the passage of light through the retina.

Question 14

Visual Pathways

Answer 14

Geniculostriate pathway & Tectopulvinar pathway

Question 15

Explain the streams of the Geniculostriate pathways

Answer 15

Bipolar cells synapse with the rods and cons (induce graded potentials)
Send information to Retinal Ganglion Cell (RGC)
Send axons to the brain (optic nerve)
Optic nerves leave the eye and cross at the optic chiasm. The right half of each eye’s visual field is transmitted to the left hemisphere, the left half of each eye’s visual field is transmitted to the right hemisphere. Information relays the lateral geniculate nucleus (LGN) of the thalamus. LGN projects to the primary visual cortex or striate cortex (or V1). V1 contains a retinotopic map of the visual field.

Question 16

What is the Geniculostriate pathways role?

Answer 16

This pathway takes part in pattern recognition and conscious visual functions.

Question 17

What happens if there is a damage to Geniculostriate pathways?

Answer 17

Damage to this system can produce impairments in pattern, color, and motion perception.
Visual-form agnosia which is the inability to recognize objects.

Question 18

Explain the streams of the Tectopulvinar Pathway

Answer 18

Optic nerve projects to the superior colliculus (midbrain). Reaches visual association areas in the temporal and parietal lobes through relays in the lateral posterior-pulvinar complex of the thalamus. This is more of a basic level pathway.

Question 19

What is the Tectopulvinar pathways role?

Answer 19

Detects stimuli and helps orient us to stimuli. Sophisticated in fish, amphibians and reptiles. In mammals, there is additional projection from colliculus to cortex via the pulvinar nucleus. Provides information about absolute spatial location of objects.

Question 20

What happens if there is a damage to Tectopulvinar pathways?

Answer 20

Visual ataxia.

Question 21

Damage to ventral and dorsal stream can cause…? (Secondary visual processing)

Answer 21

Can cause more complex perceptual problems

e.g. agnosias

Question 22

Anton’s syndrome

Answer 22

It is a visual anosognosia, Objectively blind but lack awareness into blindness and confabulate what they see. hypothesis that occipital lobe damage disconnects incoming information from association with the speed-language areas of the brain. Visual imagery is received but cannot be interpreted, the brain confabulates a response.

Question 23

Blindsight

Answer 23

It is a cortical blindness. No conscious vision due to lesions to primary visual cortex (striate), but able to detect, localize and discriminate visual stimuli better than chance. Hypothesis that other pathways (not through striate) are intact leading to non-conscious processing of visual information.

Question 24

What is the process of energy transduction in hearing?

Answer 24

Air pressure waves are converted into mechanical energy, which activates the auditory receptor cells which in turn produce action potentials.

Question 25

The process of hearing

Answer 25

auditory receptors detect the frequency, amplitude, and complexity of air pressure waves. Humans rapidly lose high-frequency hearing (age and exposure)

Question 26

What are the most important frequencies to humans?

Answer 26

those of speech in the lower frequencies.

Question 27

Projections of Retinotopic map

Answer 27

Right visual field projects to left visual cortex. Central visual field projects to the peripheral visual cortex. Peripheral visual cortex projects to medial cortex. Upper visual field projects onto the lower visual cortex. Lower visual field projects onto upper visual cortex.

Question 28

What are the physical dimensions of sound waves? Explain.

Answer 28

Frequency (pitch): the rate at which waves vibrate. Corresponds to our perception of pitch.
Amplitude (loudness): The intensity of sound. Corresponds to our perception of loudness.
Complexity (timber): most sounds are a mixture of frequencies. The particular mixture determines the sound’s timber or perceived uniqueness. Timber provides information about the nature of sounds.

Question 29

List the main anatomy of the ear

Answer 29

Outer ear: Pinna and external ear canal
middle ear: Eardrum and the ossicles, the hammer, anvil and stirrup.
inner ear: Oval window and cochlea (contains hair cells that convert sound to electrical impulses).

Question 30

What is the tonotopic representation?

Answer 30

different points on the basilar membrane and the cortex present different sound frequencies. Also maintained in cortex.

Question 31

Auditory pathways

Answer 31

Axons of hair cells from the auditory nerve (8th cranial nerve) . Auditory nerve projects to the dorsal or ventral cochlear nuclei or to the superior olivary nucleus (brainstem). Next, axon project to the inferior colliculus (midbrain) and then relay through the medial geniculate nucleus ( thalamus)
One pathway projects to the primary auditory cortex, the other projects to the secondary auditory cortex.

Medial geniculate= M for music
Lateral geniculate= L for light

Question 32

Cross of over of information in auditory system and how is this cross over helpful?

Answer 32

most of the information cross over. About 60% crossover and 40% are ipsilateral. So helps when you have a brain damage you can still process information through the other ear.

Question 33

What happens if there is a damage to the primary auditory pathway?

Answer 33

Can cause hearing loss. However, some auditory information is passed ipsilaterally.

Question 34

Secondary auditory pathway/processing location and role?

Answer 34

Near the semantic temporal area “what” stream.
ID sounds and language. (in the right hemisphere– discrimination of non-speech sounds, in the left hemisphere discrimination of speech sounds)

Question 35

Vestibular system general function and location?

Answer 35

Motion and balance. Allows us to perceive our own motion and to maintain balance (done by the hair cells that bend when we move.) It is located in the inner ear, with a semicircular canals which can respond to any movement of the head. Otolith organs respond to head’s linear acceleration and it is sensitive to changes in the position of the head with respect to gravity.

Question 36

What are the vestibular system pathway?

Answer 36

Hair cells project over the 8th cranial nerve to nuclei in the brainstem. Connection to the midbrain and cerebellum.

Question 37

What is the process of energy transduction in somatosensory?

Answer 37

mechanical energy (touch, pressure) activates mechanoreceptors that generate action potentials. Tissue damage release neurotransmitters that activate pain fibers and produce action potentials.

Question 38

Name four major somatosensory submodalities and what they are?

Answer 38

Nociception: perception of unpleasant stimuli– pain, temperature, itch.
Haps is: tactile perception of objects using fine touch and pressure.
Proprioception: perception of body location, movement
4th submodality mediates balance.

Question 39

Name the two somatosensory pathways

Answer 39

Posterior spinothalamic tract.

Anterior spinothalamic tract.

Question 40

Posterior spinothalamic tract

Answer 40

Hapsis and proprioception.
Sensory receptior in the body project into spinal cord. Ascends to contralateral ventrolateral thalamus—which is the somatosensory cortex (S1 and S4).

Question 41

Anterior spinothalamic tract

Answer 41

Nociception
smaller less myelinated, more slowly adapting. Send information across to the other side of the cord, where they form the anterior spinothalamic tract.
Anterior fibers eventually join posterior hapsis and proprioception fibers in medial lemniscus (brainstem/medulla). Also terminate primarily in ventrolateral thalamus, as well as in posterior thalamus. Then message is relayed to areas 3,2,1 of the cortex.

Question 42

What is Taste and Olfaction

Answer 42

Transduction of energy, chemical molecules in the air and in food fit into receptors and activate action potentials.

Question 43

Taste and smell pathways

Answer 43

Gustatory pathway

Olfactory pathway

Question 44

Explain gustatory pathway

Answer 44

cranial nerves 9, 10, 7 carry information from the tongue and enter the solitary tract (pons). Two pathways emerge from the solitary tract, one route projects to S1 and S2 via the ventroposterior medial nucleus of the thalamus. Other routs leads to pontine taste are which in turn projects to the amygdala and lateral hypothalamus.

Question 45

Explain olfactory pathways

Answer 45

Axons of olfactory receptor relays synapses in the olfactory bulb. Bulb’s major output is lateral olfactory tract it passes ipsilateral to the pyriform cortex the amygdala and the entorhinal cortex. Pyriform cortex project to dorsomedial nucleus in the thalamus, it in turn projects to orbitofrontal cortex considered the primary olfactory neocortex.
Single cell recordings from this pathway suggests two general classes of neurons, some responsive to specific odors and some more broadly tuned.

Question 46

What is perception?

Answer 46

Sensory impression are affected by contexts, emotion states and experiences.

Question 47

What is synesthesia?

Answer 47

Involves sensory mixing, ability to perceive a stimulus of one sense as the sensation of a different sense. More than 100 kinds and can run in the family. Most common type is colored hearing.

Question 48

What is self-perception?

Answer 48

Body image is product of both the brain’s representation and sensory information provided by the body to the brain. Moment to moment updating of the brain’s representation through sensory experience ensures that reality and inborn body representations are congruent.

Question 49

Exteroceptive receptors

Answer 49

Response to external stimuli.

Question 50

Interoceptive receptors

Answer 50

Responses to internal stimuli, help interpret meaning of external stimuli , The ones in muscles and joints and in vestibular organs of inner ear tell us about our position and movement

Question 51

Optic flow

Answer 51

Visual stimuli seem to stream past when you run

Question 52

Auditory flow

Answer 52

Distinguishes changes in intensity of sound because of our changing location.