exam 2 Flashcards
(64 cards)
1
Q
Receptors
A
An entire cell that is supposed to respond to a physical/chemical stimulus and change that stimulus into a neural (chemical) signal.
2
Q
What happens when the sensory info reaches the primary somatosensory cortex
A
-sensory info in, motor behavior out
3
Q
The retina-geniculate-striate pathway and its
retinotopic map
A
At each location, the order of the parts of the image are maintained…that is, there are retinotopic maps in both the lateral geniculate nucleus and primary visual cortex
4
Q
Receptive fields: “center-surround”
responses
A
- Visual receptive field:
an area of visual space
where it is possible for
light to change the firing rate of a neuron.
5
Q
What is Nociception?
A
Pain
6
Q
Higher Order Processing:
A
Parallels with the visual system
7
Q
Problems for the retina based on the arrangement of neurons
A
- Light is filtered and
distorted on its way
through the neuronal
cell layers to the
receptors - Axons of the retinal
ganglion cells ultimately
have to cross through
the retina to make it out
of the eye
8
Q
How does info go from the skin to the brain
A
- Information enters the spinal cord through the dorsal root ganglion
- Contralateral projection to the ventral posterior nucleus of the thalamus
- Goes to the primary somatosensory cortex
9
Q
Descending Motor Pathways
A
- Axons from the motor cortex don’t innervate muscles directly
-> They either directly (1 synapse) or indirectly (many synapses) innervate neurons of the ventral horns of the spinal cord - The neural element that ultimately “talk” to muscles and get them to contract are spinal motor neurons
10
Q
Constricting of the pupil
A
Pupil constricted= Improves acuity
11
Q
Audition- Physical stimulus
A
- The physical stimulus for audition are vibrations of air molecules
12
Q
Common Theme Alert: Receptive fields
A
The receptive field of a neuron is a region of physical space where it is possible for a physical stimulus to alter the firing rate of the neuron
being measured.
13
Q
Common Theme Alert: Contralateral projections
A
- Somatosensation: touch to left side of the body is processed by
right primary somatosensory cortex; touch to the right side of the body is processed by left primary somatosensory cortex - Motor: movement of left side of the body is governed by right
primary motor cortex; movement of the right side of the body is
governed by left primary motor cortex - Vision: left visual world is processed by right primary visual
cortex; right visual world is processed by left primary visual
cortex
14
Q
Primary auditory cortex
A
- Primary auditory
cortex is located within
the temporal lobe of the cortex - Just like visual cortex
(located in the occipital
lobe), it is organized in
columns
15
Q
Physical stimuli
A
- Wavelengths of light
- Sound waves
- Chemicals
- pressure
16
Q
From the ear on through the brain
A
- While auditory information
makes a few more stops in brainstem and midbrain regions, like vision, it still goes through the thalamus
before reaching the primary auditory cortex. - Region of the thalamus that
processes auditory
information is called the
medial geniculate nucleus of
the thalamus.
17
Q
nasal hemiretina & temporal hemiretina
A
- Our retinas can be thought of as being divided at the fovea
– We have a nasal hemiretina
– We have a temporal hemiretina
– the nasal hemiretina from one eye sees a different part of the visual world than the temporal hemiretina
from that same eye
– HOWEVER, the nasal hemiretina from one eye and the temporal
hemiretina, from the other eye, see the same part of the visual world
18
Q
Receptive fields in the organ of corti
A
- tones of different frequencies will cause
hair cells in different parts of the organ
of corti to be stimulated - the organ of corti has a tonotopic map:
regions that respond best to one particular tone are neighbored by regions that respond best to a tone of slightly
different frequency. - this map is preserved all the way to the
cortex – just like with vision
19
Q
Top-Down Control
A
Higher-order areas of the nervous system (e.g. the cortex) alter
sensory and motor processing in the peripheral nervous system – some examples:
1.Visual cortex fills in gaps in our visual perception due to images
falling on our blind spot
2.Auditory cortex filters out non-important auditory information
(e.g. cocktail party effect)
3.Motor cortex governs (e.g. inhibits) spinal reflexes
20
Q
Semi-circular canals
A
- Information from the hair cells of the semicircular canals travels along the cranial nerve VIII - the
auditory nerve. - Information is processed by the brainstem as well as the
cerebellum. - This system works in close collaboration other sensory
systems – especially with the visual system. - Vestibulo-ocular reflex
demonstration
21
Q
Descending Motor Pathways: crossing the midline
A
- Right primary motor (frontal) cortex controls muscles of the left side of the body
- Left primary motor (frontal) cortex controls muscles of the right side of the body
CROSSING THE MIDLINE
22
Q
Getting information about light from the
eye to the brain
A
- Information leaves the
retina via the axons of
the retinal ganglion cells - Axons from the retinal
ganglion cells course (or
travel) via the optic
nerve
23
Q
Organ of Corti:
chock full of hair cells
A
- Deflection of hair cells in one direction mechanically causes ion channels to open.
- Thus, the receptors for sound are hair cells
24
Q
What is Hapsis
A
fine touch and pressure
25
Wavelength
color
26
The stimuli that we sense- falls in what realm?
Chemistry and Physics
27
What is proprioception
body awareness
28
Plasticity
- Brain structures can change to cope better with the environment
29
Right & Left cortex: The homunculus- a somatosensory map
- Right primary somatosensory (parietal) cortex: Processes touch to the left side of the body
- Left primary somatosensory (parietal) cortex: Processes touch to the right side of the body
- CROSSING THE MIDLINE
30
Rods
- Rod-mediated vision
dominates in dim light
– More sensitive to light
than cones
– Poor acuity
– Lack of color
31
Turning light into neural signals: take home messages
* Bleaching of rhodopsin stops rods from firing action
potentials
* Inhibition starts a string of effects on “downstream” neurons that leads to the excitation of retinal
ganglion cells
* retinal ganglion cells carry information out of the eye and to the brain
32
Amplitude
Brightness
33
Top-down control
- Cortical neurons can also control inhibitory
interneurons and stop
reflexes from happening like the Babinski reflex
- Loss of cortical control can lead to reflexes taking over
34
Sympathetic and Parasympathetic Nervous Systems: playing a role in the opening of the
iris
* Sympathetic activation
leads to pupil dilation
* Parasympathetic
activation leads to
pupil constriction
– acts via acetylcholine
receptor
– Atropine is an
acetylcholine receptor
antagonist
35
Motor unit
A single spinal motor neuron and all of the individual muscle fibers it contacts.
36
Solution for axons
Completion: visual system uses
information from the receptors
around the blind spot to complete
broken images
37
Turning vibrations into neural signals- The key terms
* Tympanic membrane
* Ossicles
* Cochlea
- Oval window
* Organ of Corti
- Hair cells
38
What determines the speed of the action potential
The myelin and diameter of the neuron
39
Solution for light
Fovea: specialized area of the retina with a thinning of the retinal ganglion cell layer. This is an area of high
acuity.
40
Somatosensory receptive fields
- Touching the center of the receptive field (top row): increase in firing rate
- Touching the surround of the receptive field (middle row): Decrease in firing rate
- Touching center AND surround: two responses cancel each other out
- Touching outside of the receptive field (bottom row): no change…it's not the neurons receptive field!
41
Ventral Stream
Important for identifying what objects
are
42
Where is the primary somatosensory cortex
It's in the parietal lobe, posterior to the central sulcus
43
The Reflex: the simplest interaction between sensory and motor systems
- The status of a muscle is monitored by receptor systems, e.g. muscle spindle neurons.
- Muscle spindles are embedded in the
muscle itself and report the length of muscles. These neurons increase
the firing rate when the muscle is
stretched.
- When muscles get stretched there is
often an immediate effort by the body to work against that stretch. That is, we have stretch reflexes.
44
Nasal hemi-retina & Temporal hemi-retina
- axons from the nasal hemi-retina cross the midline; axons from the
temporal hemi-retina don’t.
45
Semi-circular canals: sense organ of the
vestibular system (proprioception)
* Located next to the Cochlea
* Sense organ for the vestibular system is the semicircular canals
– Information related to head movements and intensity of head
movements
– Important for balance
* Translates head movement into
neural signals by the movement
of fluid in the semicircular canals
and the stimulation of hair cells
46
What is a dermatome
An area of skin that reports touch through neurons whose bodies lie within a single dorsal root ganglion
47
Hapsis (touch, pressure) system
- Topography
- orderly entry of info from dermatomes into the spinal cord
48
Cones
- Cone-mediated vision
dominates in ample
light
– High acuity
– Color
49
Acetylcholine
A neurotransmitter used by neurons to "talk to" muscles (cause them to contract
50
The homunculus: a somatosensory map
Neurons that answer to touch on one part of the body are next to neurons that answer to immediate adjacent areas of the body
51
Thalamus
* Vision: lateral geniculate
nucleus
* Audition: medial geniculate
nucleus
* Somatosensation: ventral
posterior nucleus
52
Sensory and motor systems working
together
* Vestibular-ocular reflex
* Head movements cause equal and opposite eye movements
53
What are the three classes for somatosensation?
- Nociception
- Hapsis
- Proprioception
54
Receptors
degree of convergence affects sensitivity and acuity
55
Dorsal stream
Important for determining where
stimuli are in space
56
Dilation
Wider pupil= Increases sensitivity
57
Information from the retina goes where
Information from the retina projects to the
lateral geniculate nucleus which projects to primary visual cortex
58
Common Theme Alert: Receptive fields
The receptive field of a neuron is an area of physical space where it is possible for a physical stimulus to alter the firing rate of the neuron being measured
59
Where does the information travel
- Starts at the surface of the skin, action potential then goes through the axon.
- From the axon, in foes to the cell body, which lies in the dorsal root ganglion travels to the spinal cord
60
Visual fields and the “crossing” of information
- info from the left visual world (visual field) is processed by our right visual cortex
- information from the
right visual world is processed by our left visual cortex.
* HOWEVER: both eyes receive information from both visual fields.
61
The sense organ of the eye: The Retina
Retina: 5-layered sense organ for vision
Back-most layer:
receptors for light (rods
and cones)
Front-most layer: retinal
ganglion cells (axons
travel out of the eye and to the brain)
62
Binocular disparity
Images on the retina are 2-dimensional... with the image on each retina offset (binocular disparity), we can make a 3-dimensional psychological image
63
How do sodium channels open
A physical disturbance opens the channels, which can lead to depolarization-> ACTION POTENTIAL
64
What is the goal of sensory systems
To turn physical stimuli
into psychological experiences
