Unit 1: Sensory and Motor Systems Flashcards
(278 cards)
1
Q
Do we pay more attention to stimuli that change or stay the same?
A
We pay more attention to changing stimuli.
2
Q
Do we perceive reality?
A
No.
Neurons get fired that our brain then associates with a stimulus even if that is not what it actually is.
Ex: Capsaicin is not really hot but it stimulates our hot thermoreceptor neurons which makes us feel that way.
3
Q
What is the olfactory nerve and its relationship to the olfactory bulb?
A
The olfactory nerve is cranial nerve I.
The olfactory nerve is the branches from the olfactory bulb.
4
Q
What does ORN stand for?
A
Olfactory receptor neuron
5
Q
How are olfactants recognized by ORNs?
A
ORNs have 1 GPCR olfactory receptor that only responds to a few olfactants with differing strengths.
6
Q
How does scent information reach the olfactory bulb?
A
Olfactory receptors
Glomeruli = converges ORNs with the same receptor type.
Olfactory nerve (cranial nerve I)
7
Q
What are the olfactory bulb’s primary targets?
A
Pyriform complex → orbitofrontal cortex
- The location of smell information is no longer as segregated as it was in the glomeruli.
Olfactory tubercle
Amygdala
Entorhinal cortex → hippocampal formation
8
Q
Does smell information have to go through the thalamus to get to the cortex?
A
No. It is the only sensory system that does not go through the thalamus to get to the cortex.
9
Q
What are the olfactory bulb’s secondary targets (projections from primary targets to secondary targets)?
A
Orbitofrontal cortex ⇆ thalamus
Hypothalamus
10
Q
What is anosmia?
A
The loss in olfactory perception.
11
Q
What is orthonasal olfaction
A
Smelling odorants exterior to your body.
12
Q
What is retronasal olfaction?
A
Smelling odorants inside your mouth.
13
Q
What is cranial nerve VII?
A
Facial nerve; connected to the palate and anterior ⅔ of the tongue.
14
Q
What is cranial nerve IX?
A
Glossopharyngeal nerve; connected to the posterior ⅓ of the tongue.
15
Q
What is cranial nerve X?
A
Vagus nerve; connected to taste buds in the pharynx and upper portion of the esophagus.
16
Q
What is cranial nerve XII?
A
Cranial nerve VII = hypoglossal nerve; intrinsic muscles of the tongue.
17
Q
What is cranial nerve II?
A
Optic nerve; vision.
18
Q
What is cranial nerve III?
A
Oculomotor nerve; moves the eyes. Parasympathetic to the pupillary constrictor and ciliary muscles.
19
Q
What is cranial nerve IV?
A
Trochlear nerve; moves the eyes downward and inward.
20
Q
What is cranial nerve V?
A
Trigeminal nerve; sensations of touch, pain, and temperature for the face and meninges. Also innervates the muscles of mastication and tensor tympani muscle.
21
Q
What is cranial nerve VI?
A
Abducens nerve; lactus rectus muscle. Controls the outward (abduction) movement of the eye.
22
Q
What is cranial nerve VIII?
A
Vestibulocochlear nerve; hearing and vestibular sensation.
23
Q
What is cranial nerve XI?
A
Spinal accessory nerve; controls neck muscles, specifically the sternomastoid muscle and the upper part of the trapezius muscle.
24
Q
What are papillae?
A
Taste bud bumps.
25
What are type I cells in taste buds?
Type I = supportive glial cells
26
What are type II cells in taste buds?
Type II = contains receptors for sweet, salty, bitter, and umami tastants.
No synaptic mechanisms, just ATP.
27
What are type III cells in taste buds?
Type III = contains receptors for sour and some salty tastants.
Does have synaptic architecture.
28
What is the pathway for gustatory information?
Taste cells → gustatory afferent neurons → cranial nerves (7/9)→ nucleus of the solitary tract.
29
What does the nucleus of the solitary tract project to with taste information?
Ventral posterior medial (VPM) thalamus → insular and frontal taste cortices → amygdala
Hypothalamus and amygdala → nucleus of the solitary tract
30
Why do optical illusions exist?
Light, darkness, and color are all perceptions. Our visual system plays tricks on us constantly and we are not really sure why. It could be due to the way some edges are or the context of the object that changes how we perceive it.
31
What is the purpose of the pupil?
To be an aperture that limits the amount of light that can enter the eye. This limitation allows us to discern from where the light is coming from as it is hitting a particular spot on the retina.
32
Why does pupil dilation make someone's vision blurry?
When people’s pupils are dilated, the aperture doesn’t work so vision looks blurry. Light is bouncing all over the retina and we can't discern exactly where it is coming from. There is also too much light coming in so we are sensitive to it.
33
What is resolution?
The minimum distance needed to discriminate between two different points in space.
34
What is the uveal tract?
Runs behind the retina and contains the iris, ciliary muscle, and choroid.
35
Fovea
An area filled with cones and no blood vessels which is used for high visual acuity.
36
Optic disk
Where the blood vessels come from and where the axons go. There are no photoreceptors here so it is a blind spot.
37
Choroid
Supporting cells for the retina. Takes in old photoreceptor discs that are damaged. Also, provides melanin so it takes in light and prevents it from bouncing back into the retina which would reduce resolution.
38
Macula lutea
The area surrounding the fovea.
39
Macular degeneration
A loss of photoreceptors/damage in the area that decreases high visual acuity.
40
Ciliary muscle
An anterior portion of the uveal tract that changes the shape of the lens.
41
Ametropia
Discrepancies in the cornea or eyeball shape.
42
What causes nearsightedness/myopia?
Light is focused in front of the retina so individuals can focus on nearby objects, they cannot focus on objects that are far away.
43
What causes farsightedness/hyperopia?
Due to a weak refracting system or an eyeball that is too short. People cannot focus on objects that are near to them as the focus of the light extends past the retina.
44
Which retinal cells have action potentials?
Only retinal ganglion cells have action potentials. All other cells have graded potentials.
45
What is the direct retinal pathway?
Cone → bipolar cell → ganglion cell
This can become indirect by adding a stop at an amacrine cell before the ganglion cell.
46
What is the indirect retinal pathway?
Indirect: Rod → bipolar cell → amacrine cell → ganglion cell
47
Can rods and codes interact with each other?
Yes. They can do so directly through gap junctions or indirectly through horizontal or amacrine cells.
48
How do photoreceptors react when they are hit with light?
They hyperpolarize which leads to a decrease in neurotransmitter release.
49
Which photoreceptors are more sensitive to light (become more active in darker conditions)?
Rods.
50
Which photoreceptors provide color vision?
Cones.
51
Which photoreceptors adapt faster?
Cones.
52
How do ON-center ganglion cells become active?
When the light hits its receptive center.
53
How do the OFF-center ganglion cells become active?
When the light hits its receptive surround area.
54
How do ganglion cells figure out what is in their surround/center?
The ganglion cells receive multiple inputs and they have surround and center receptive fields.
55
How do ganglion cells compare light and dark conditions?
They compare it in contrast to the ambient lighting.
56
What is the OFF-center information pathway in the retina?
Light hits the cells in the surround receptive field (-) → surround photoreceptor cell becomes hyperpolarized → bipolar cell inhibited → ganglion cell inhibited
So, in the OFF-center pathway, light causes this pathway to become silent.
57
What is the ON-center information pathway in the retina?
Light hits the cells in the surround receptive field (-) → center photoreceptive cell becomes hyperpolarized → bipolar cell depolarized → ganglion cell active.
So, in the ON-center pathway, light causes this pathway to become active.
58
What is the cortex visual processing pathway from the eye to the thalamus?
Optic nerve → optic chiasm → hypothalamus, pretectum, superior colliculus, and lateral geniculate nucleus (LGN) of the thalamus.
59
Why does the hypothalamus receive visual information?
The hypothalamus controls the regulation of circadian rhythms based on light information.
60
Why does the pretectum receive visual infromation?
The pretectum controls the pupillary light reflex.
61
What is the pathway from the pretectum to control the pupillary light reflex?
Pretectum → Edinger-Westphal nucleus in the brainstem → ciliary ganglion in the eye.
62
Why does the superior colliculus receive visual information?
The superior colliculus regulates the orienting movements of the head and eyes.
63
Does the LGN have parallel mapping of the retina?
Yes. The LGN does retain retinotopic information from the retina.
64
What are thalamocortical relay cells?
The cells in the LGN that receive parallel ganglion cell information.
65
What is the visual pathway after the LGN?
LGN → optic radiation → striate cortex (primary visual cortex; V1).
66
What are midget cells/P cells and what kind of information do they transmit?
Ganglion cells that project to the four parvocellular layers of the LGN.
Characteristics:
-Respond in a sustained fashion
-Transmit information about color
-Respond poorly with low-contrasting stimuli.
-Used for color discrimination and detecting fine details about an object.
67
What are parasol cells/M cells and what kind of information do they transmit?
Ganglion cells that project to the two magnocellular layers of the LGN.
Characteristics:
-Large receptive field
-Activated only for a short time.
-Cannot transmit information about color
-Used for movement detection, temporal resolution to determine the speed, location, and direction of a fast-moving object, and low-contrast resolution.
68
What are koniocellular cells and what kind of information do they transmit?
A separate ganglion pathway that projects to the interlaminar (interlayer) zones of the LGN, layers 2-3, and is not highly understood.
Characteristics:
-Distinct receptive fields
-Gives some information about color, especially short-wave color information, and directionality.
69
What layer of the LGN only responds to information from one eye?
Layer 4 of the LGN.
70
Do the layers of the LGN (excluding layer 4) respond equally to information from each eye?
No, they have ocular dominance where they respond to visual information from one eye more than other but the activity is not exclusive to input from one eye.
71
Is ocular dominance maintained throughout columns?
Yes, (except for layer 4 which does not have ocular dominance).
72
What information does the dorsal optic radiation carry?
The dorsal optic radiation carries information from the inferior visual field (superior retinal quadrants).
73
What information does the ventral optic radiation carry?
The ventral optic radiation carries information from the superior visual field (inferior retinal quadrants).
74
What is the retino-genicular-cortical pathway?
The path from thalamocortical relay cells in the LGN to layer 4 of the primary visual cortex.
75
What area of the retina receives the most processing space in the primary visual cortex?
The fovea.
76
How are receptive fields organized in the primary visual cortex?
By columnar organization.
77
Which cones have most recently diverged from each other?
M and L cones.
78
How do we see such a wide range of colors if the wavelength the different cones react to overlap?
Their activity is compared. There are +L/M- cells for instance which become active from L cone activation and inhibited by M cell activation. Both L and M cones oppose the activity of S cones. By knowing which cones are active and at what strength gives us information on the color.
79
What leads to dichromatic vision?
A mutation in an M or L cone.
80
How does comparing different kind of cone activity increase color perception?
It creates contrast which allows us to see color better.
81
What is color constancy?
The ability to still see the same colors in different lighting conditions by comparing the differences in wavelength which is still the same.
82
How do color optic illusions work?
Optic illusions that involve us seeing a color that isn't really there is due to the fact that we perceive color in context of what is around it.
83
What is frequency and how is it perceived?
Frequency is the speed of the sound waves and it is perceived as pitch.
84
What is amplitude and how is it perceived?
Amplitude is the height of the sound wave and it is perceived as volume.
85
What function does the outer ear have?
Sound localization vertically and amplifies sound that humans respond to better.
86
What happens when sound hits the eardrum?
The ossicles move which then tap on the oval window and move the perilymph in the cochlea.
87
How are the tectorial and basilar membranes attached to the outer hair cells and how does this cause shearing?
The apical part of outer hair cells is connected to the tectorial membrane and the basal part of the outer hair cells is connected to the basilar membrane.
The tectorial and basilar membrane have different pivot points which leads to shearing that moves the hairs of outer hair cells.
88
Do hair cells in the ears have action potentials?
No, they use graded potentials.
89
Which parts of the basilar membrane responds to high frequencies?
The base of the basilar membrane.
90
Which parts of the basilar membrane responds to low frequencies?
The apex of the basilar membrane.
91
What two pieces in the ear allow frequency to be coded?
The firing rate of the hair cells and the movement of the basilar membrane.
92
How do outer hair cells influence the basilar membrane?
Outer hair cells control the responsiveness of the basilar membrane.
This can help focus on certain frequencies, such as in loud environments.
93
Where are the cochlear nuclei?
In the rostral medulla.
94
What do the ventral cochlear nuclei focus on?
"Where is it?"
95
What do the dorsal cochlear nuclei focus on?
"What is it?"
96
Is auditory information mostly sent bilaterally or unilaterally?
Bilaterally.
97
Where is sound localized based on timing differences?
The medial superior olive (MSO) in the superior olivary nuclei
98
Where is sound localized based on intensity differences?
The lateral superior olive (LSO) in the superior olivary nuclei
99
How does the medial superior olive (MSO) compare interaural timing differences?
They have several areas and the MSO neurons only fire if they receive sound information from both ears at the same time.
100
How does the lateral superior olive (LSO) compare interaural intensity differences?
The intensities inhibit each other. Which side has more excitation activates LSO neurons which tells which ear is getting more intense sounds.
101
Where do the What is it?” and “Where is it?” pathways converge?
The inferior colliculus.
102
Is there a topographic map for auditory information in the inferior colliculus?
No.
103
What is the pathway for sound after the inferior colliculus?
Inferior colliculus → medial geniculate nucleus (MGN) of the thalamus.
104
What type of sound information does the ventral medial geniculate nucleus respond to?
Responds to frequency, loudness, and interaural differences.
105
What type of sound information does the medial medial geniculate nucleus respond to?
Responds to timing, sound duration, and loudness.
106
What type of sound information does the medial dorsal geniculate nucleus respond to?
Only responds to certain combinations of frequencies.
107
What kinds of organization does the primary auditory cortex have?
Columnar and topographic organization.
108
How does the primary auditory cortex increases contrast between different sounds?
The hot spots for sounds are surrounded by inhibition.
When sound hits a spot, it inhibits information from nearby spots. This helps to increase contrast.
109
What type of sound information does the anterior belt of the auditory cortex respond to?
Responds to auditory features.
110
What type of sound information does the posterior belt of the auditory cortex respond to?
Responds to auditory location, but has no topographic map.
111
What do the ventral auditory-object processing pathway focus on?
"What is it?"
112
What does the dorsal auditory-motion processing pathway focus on?
"Where is it?"
113
What is glabrous skin and where is it found?
Hairless skin. Found on the palms of the hands, the bottom of the feet, and the lips.
114
What is the purpose of hairless skin?
Meant for discriminative touch to accurately assess the size, shape, and texture of objects.
115
What somatosensory afferent fibers are used for proprioception?
Ia, IIa
116
What somatosensory afferent fibers are used for touch?
A𝛽
117
What somatosensory afferent fibers are used for pain and temperature?
Aδ
117
What somatosensory afferent fibers are used for pain, temperature, and itch?
C fibers
118
When we sit down for a long time, why do we stop perceiving the chair we are sitting on?
Because the rapidly adapting afferents stop responding.
119
What are the characteristics of Merkel cells?
Slowly adapting, with the highest spatial resolution.
They also surround hair follicles in hairy skin.
120
What are the characteristics of Meissner cells?
Rapidly adapting with a bigger receptive field than Merkel cells.
Sensitive to low-frequencies vibrations that occur when you touch the ridges or edges of an object.
121
What are the characteristics of Pacinian corpuscles?
Acts as a filter that only responds to high-frequency vibrations.
Rapidly adapting with large receptive fields.
122
What are the characteristics of Ruffini afferents?
Slowly adapting fibers that respond to stretches of the skin.
123
Do joints have rapidly or slowly adapting afferents?
Rapidly adapting afferents.
124
What are muscle spindle organs?
Intrafusal muscle fibers that provide information about the stretch of the muscle.
125
Do muscle spindle organs provide the force of contraction?
No.
126
What are Golgi tendon organs?
Muscle tendons that provide information about the tension in the muscle. Helps prevent the muscle from tearing.
127
What are the different components that help the brain know where the body is in space?
Muscle spindle, Golgi tendon organ, visual system, and vestibular system.
128
What is the bodily somatosensory information pathway?
Dorsal column → medulla medial leminscus → ventral posterior lateral (VPL) thalamus.
129
When does the bodily somatosensory information pathway decussate?
In the medulla.
130
What is the proprioception information pathway for the upper body?
Enters the dorsal column pathway immediately.
131
What is the proprioception information pathway for the lower body?
Clarke’s nucleus → dorsal spinocerebellar tract.
132
What information does area 3a of the primary somatosensory areas receive?
Receives proprioceptive inputs.
133
What information does area 3b of the primary somatosensory areas receive?
It is the main somatosensory input area.
134
What information does area 1 of the primary somatosensory cortex receive?
Responds to cutaneous stimuli to determine the texture of objects.
135
What information does area 2 of the primary somatosensory cortex receive?
Responds to tactile and proprioceptive information to determine the size of objects.
136
How plastic is the primary somatosensory cortex?
It has a dynamic equilibrium so if certain body parts are used more or less, the primary somatosensory cortex will change to reflect that.
137
What is first pain?
Sharp pain mediated by Aδ fibers.
138
What is second pain?
Throbbing pain mediated by C fibers.
139
What information does the anterolateral system transmit?
Pain.
140
Where does the anterolateral system decussate?
In the spinal cord.
141
What information does the lateral spinothalamic pathway of the anterolateral system carry?
Conveys pain and temperature signals.
142
What information does the anterior spinothalamic pathway of the anterolateral system carry?
Conveys sensory discriminative parts of pain including its location, intensity, and quality.
143
What pain information constitutes the sensory discriminative pathway?
Provides the intensity, location, and quality of nociceptive stimuli.
144
What is the pathway for sensory discriminative pathway in the brain?
This information from the anterolateral system goes through the ventral posterior thalamus and ends up at the primary somatosensory cortex.
145
What pain information constitutes an affective-motivational pathway?
Emotional response to pain.
Ex: Fear, anxiety, and autonomic PNS activation.
146
What is the pathway for the affective-motivational pathway in the brain that includes going through the thalamus?
This information from the anterolateral system goes through the midline thalamic nuclei and goes to the anterior cingulate cortex and insular cortex.
147
What is the pathway for the affective-motivational pathway in the brain that does NOT include going through the thalamus?
Without going through the thalamus, the information also goes to the amygdala, hypothalamus, periaqueductal grey, superior colliculus, and reticular formation.
148
What is hyperalgesia?
Increased pain response to a painful stimulus.
149
What is allodynia?
Painful perception to a non-painful stimulus.
150
Is it possible to have peripheral sensitization to pain?
Yes.
151
Is it possible to have central sensitization to pain?
Yes.
152
What is the top-down modulation pathway for pain?
Somatic sensory cortex → amygdala, hypothalamus, periaqueductal grey → parabrachial nucleus, medullary reticular formation, locus coeruleus, and raphe nuclei → dorsal horn of the spinal cord.
153
What is windup and why does it happen?
Windup = increase in the perception of pain from a sustained intensity of a painful stimulus.
This happens due to a removal of a Mg2+ block on NMDA receptors which increases glutamate output.
154
Where are proximal muscles controlled in the spinal cord?
Proximal muscles are controlled medially in the spinal cord.
155
Where are distal muscles controlled in the spinal cord?
Distal muscles (like the fingers) are controlled laterally in the spinal cord.
156
Do lower motor neurons medially in the spinal card contain more or less projections? Why?
They contain more and this allows for the synchronization of muscle movements.
157
Do lower motor neurons laterally in the spinal cord contain more or less projections? Why?
They have fewer projections. This allows for fine motor control.
158
What are ⍺ motor neurons?
Large motor neurons that innervate extrafusal muscle fibers.
159
What are 𝛾 motor neurons?
Smaller motor neurons that innervate muscle spindles (intrafusal muscle fibers), which provide proprioception information on muscle stretch.
160
What are slow motor units, how resistant are they to fatigue, and what is their threshold for activation?
Slow (S) motor units are small ⍺ motor neurons that innervate a few muscle fibers to form smaller motor units.
The muscle fibers contract slowly and are resistant to fatigue.
Tend to have lower thresholds for activation.
161
What are fatigue-resistant motor units, how resistant are they to fatigue, and what is their threshold for activation?
Fatigue-resistant (FR) motor units are the middle between S and FF motor units. More power than S motor units with a higher threshold but more resistant to fatigue than FF motor units.
162
What are fatigue-fatigable motor units, how resistant are they to fatigue, and what is their threshold for activation?
Fast-fatigable (FF) motor units are large ⍺ motor neurons that innervate lots of muscle fibers to generate a lot of force.
Not resistant to fatigue.
Have a higher threshold. Activated by rapid movements requiring powerful movements, such as jumping.
163
What is the size principle?
The idea that small motor units are always recruited first since they have low thresholds.
164
Are local circuit neurons in the spinal cord usually excitable or inhibitory?
Inhibitory.
165
What is the process involved in the stretch reflex?
Ia somatosensory neurons in the muscle spindle signal changes in stretch.
II somatosensory neurons in the muscle spindle signal the state of the stretch.
When the muscle is stretched away from its desired state, a reflex in the spinal cord happens where signals to ⍺ motor neurons increase/decrease to increase the force of contraction in the muscle.
𝛾 motor neurons are also activated to increase/decrease the stretch in the muscle spindle.
166
What is the difference between the muscle spindles and Golgi tendon organ?
The muscle spindle system is concerned with length while the Golgi tendon organ is concerned with force and the possibility of muscle tears.
167
What is the process involved in the flexion reflex?
Flexion reflex pathways are a reflex on flexor muscles in response to painful stimuli.
Nociceptors inhibit extensor muscles and activate flexor muscles.
In the contralateral limb, the opposite occurs to increase stability.
168
What is feedback control?
Commands determine the desired state. If the desired state turns out to be incorrect for the correct motion to occur, that feedback is sent back to the CNS.
169
What is feedforward control?
Information from sensory systems (e.g. visual) helps prepare muscles for the action desired. If the determined state is incorrect, feedback is sent back to the CNS.
170
What is the corticobulbar tract?
Upper motor neurons that terminate in the brainstem. Also governs the cranial nerve motor nuclei in the brainstem.
171
What is the corticospinal tract?
Upper motor neurons that terminate in the spinal cord.
172
What is the upper motor neuron corticospinal tract that terminates bilaterally and what does it control?
Ventral (anterior) corticospinal tract. 10% of the corticospinal neurons form this tract.
These mostly serve proximal limbs and trunk muscles.
173
What is the upper motor neuron corticospinal tract that terminates laterally and what does it control?
Lateral corticospinal tract.
These neurons decussate in the medullary pyramid and 90% of corticospinal tracts form this tract.
Terminate on ⍺ motor neurons or local circuits that led to fine motor control movement.
174
How does the primary motor cortex organize movements?
The primary motor cortex seems to have maps of map of movements or intentions.
The primary motor cortex is essentially saying, “I want to do this movement. Do what needs to be done to make it happen.” It’ll stimulate areas that represent those broad areas.
175
What is population coding?
A set of neurons vote on different actions.
It can also determine the directionality of the movement.
176
What is the function of the premotor cortex?
The premotor cortex seems to take information from other systems to make muscle movements that make sense for the context.
It helps to signal the intent of a movement.
177
What are mirror motor neurons and where are they located?
Motor neurons that fire in response to watching someone else perform a movement. They help prepare you to perform that same movement.
They are localized to the lateral premotor cortex.
178
What are vestibular nuclei?
A nuclei in the brainstem that receives vestibular information from cranial nerve VII. Used to position eye movements, neck movements, and proximal muscle movements.
179
What is the vestibulo-ocular reflex?
Movement of the eyes in conjunction with information from the vestibular system with some upper motor neuron input to cranial nerve nuclei.
180
What is the reticular formation?
A collection of several networks in the brainstem that help regulate basic body functions.
181
What does the rostral part of the reticular formation regulate?
Modulatory functions that modulate consciousness states.
Receives noradrenergic information from the locus coerulus and serotonergic information from the DR. The reticular formation then sends cholinergic projections to the diencephalon.
182
What does the caudal part of the reticular formation regulate?
Premotor functions that integrate afferent sensory information and upper motor neuron input to organize efferent motor output.
Helps control several facial reflexes such as facial expressions or movements such as sneezing.
Regulates several autonomic functions such as breathing, vomiting, and cardiac rhythms.
183
What is the reticulospinal tract?
Spinal pathway that bilaterally innervates lower motor neuron pools in the medial ventral horn to regulate the function of the trunk and proximal limbs for locomotion.
184
How are muscles affected due to upper motor neuron damage?
When upper motor neurons are damaged, there is initial paralysis and flaccidity in the muscles. There is a loss of fine motor control, especially in distal muscles. Many trunk and proximal movements are retained due to brainstem projections and local circuit neurons in the spinal cord.
185
What is the Babinski sign?
When running a stimulus up the foot usually causes the toes to flex upward instead of downward. This is likely due to increased muscle tone and hyperactivity due to reduced inhibitory signals on the reticular formation.
186
What is the cerebrocerebellum?
The largest subdivision of the cerebellum; composes the lateral sides of the cerebellum.
Regulates highly skilled spatial and temporal movements, including speech.
187
What is the spinocerebellum?
Medial and paramedian (just lateral to the median part) part of the cerebellum.
Receives input directly from the spinal cord.
188
What does the paramedian part of the spinocerebellum regulate?
Movement of the distal muscles.
189
What does the vermis/median part of the spinocerebellum regulate?
Movement of the proximal muscles and eyes.
190
What is the vestibulocerebellum?
Caudal part of the cerebellum; the smallest cerebellar subdivision.
The oldest part of the cerebellum.
Receives input from the vestibular system. Concerned with the vestibulo-ocular reflex.
191
What are the cerebellar peduncles?
Parts of the cerebellum that organize communication between the cerebellum and the cortex.
192
What is the superior cerebellar peduncle/brachium conjunctivum?
An efferent motor pathway from deep cerebellar nuclei to the motor nuclei in the dorsal thalamus.
193
What is the middle cerebellar peduncle/brachium pontis?
Afferent pathway from the pontine nuclei.
194
What is the inferior cerebellar peduncle/restiform body?
Most complex peduncle with multiple efferent and afferent tracts.
195
Does the cerebellum control movements on the contralateral or ipsilateral part of the body?
The cerebellum regulates movements of the ipsilateral part of the body, contrary to the contralateral control in the cerebrum.
196
What afferent information to the cerebellum crosses over?
What afferent information to the cerebellum does NOT cross over?
Anything that comes from the cerebrum crosses the midline while anything coming from the spine or vestibular nuclei does not.
197
Is there a topographic map in the cerebellum?
Sort of. It's just fractured with some areas represented multiple times.
198
What brain area helps the cerebellum to learn from motor errors?
Inferior olivary nucleus.
199
What is the closed cerebellum loop?
When the cerebellum provides feedback to the upper motor areas that project to the cerebellum via pontine nuclei. This helps the cerebellum to regulate its own input.
200
What is a Purjinke cell?
Destination of many afferent pathways into the cerebellum.
GABAergic and the only source of output from the cerebellum.
Projects to the deep cerebellar nuclei.
201
What are the 4 deep nuclei of the cerebellum?
Dentate nucleus, 2 interposed nuclei, and fastigial nucleus.
202
What are mossy fibers?
The name of afferent axons in the cerebellum from the pontine nuclei.
203
What are parallel fibers?
The name of the axons of granule cells that project to Purkinje cells in the outermost layer of the cerebellum.
204
What are climbing fibers? What is their function?
The name of the axons of inferior olivary cells that project to Purkinje cells in the outermost layer of the cerebellum.
Provides movement error information.
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What is the afferent pathway in the cerebellum?
Pontine nuclei mossy fibers → contralateral granule cells → Purkinje cells.
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What else do mossy and climbing fibers innervate in the cerebellum?
Climbing fibers and mossy fibers can modulate the response of deep cerebellar nuclei directly by exciting them.
They also excite the Purkinje cells that inhibit these deep cerebellar nuclei.
So the difference in activity the deep cerebellar nuclei are receiving helps modulate output.
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Is the cerebellum or upper motor system faster at correcting movement errors?
The cerebellum is much faster at movement error correction than the upper motor neurons are. It is very plastic to respond when movements are not hitting the intended target.
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What is cerebellar ataxia?
Inability to have smooth movements due to cerebellum damage.
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What is dysmetria?
Inaccurate movements that lead to under and overreaching.
Can’t correct for movement errors.
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What is the striatum?
Main center for afferent neurons into the basal ganglia. Includes the caudate and the putamen.
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What makes up the ventral striatum?
Nucleus accumbens.
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What makes up the pallidum in the basal ganglia?
Globus pallidus (external and internal) and substantia nigra pars reticulata (which includes the substantia nigra pars compacta.
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What areas do not project to the basal ganglia?
Primary auditory cortex and primary visual cortex
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What are medium spiny neurons?
Striatum cells that inhibit the pallidum.
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What does the substantia nigra pars compacta do?
Releases dopamine to the caudate and putamen.
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How does the basal ganglia form habits?
Breaking habits involved weakening the response of the direct pathway. Forming habits involved increasing the response to the direct pathway.
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What is the direct pathway in the basal ganglia?
How does it impact the thalamus?
[Substantia nigra pars compacta D1 receptors sending dopamine (+)] → Caudate and putamen (-) → GPi (-) → VA/VL thalamus (+)
This disinhibits the thalamus, allowing movements to happen.
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What is the indirect pathway in the basal ganglia?
How does it impact the thalamus?
[Substantia nigra pars compacts D2 receptors sending dopamine (-)] → caudate and putamen (-) → GPe (-) → subthalamic nucleus (+) → GPi (-) → VA/VL thalamus
This leads to inhibition of the thalamus.
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Is the direct or indirect basal ganglia pathway more broad?
The indirect pathway is more broad.
It is like the surround blocking any unwanted movements.
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How does the substantia nigra pars compacta influence the direct and indirect pathways in the basal ganglia?
The substantia nigra pars compacta increases the excitement of the direct pathway leading to a disinhibited thalamus and it decreases excitement to the inhibitory pathway, also leading to a disinhibited thalamus.
221
Why is Parkinson's a hypokinetic disorder?
The substantia pars compacta dies and thus the direct pathway is less excited and the inhibitory pathway is more excited.
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Why is Huntington's disease a hyperkinetic disorder?
Huntington’s is a hyperkinetic disorder as cells that project to the GPe die.
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What are the functions of the basal ganglia?
Focused selection of movements.
-Initiation and termination of movements.
-Suppression of unwanted movements.
Motor learning or motivated learning (dopamine is a key part of this).
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What are the main divisions of the visceral motor system?
Parasympathetic and sympathetic.
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What are autonomic ganglia?
Autonomic ganglia = autonomic lower motor neurons.
They are found outside the CNS either close to the spinal cord or in a collection of neurons, a plexus, near the targeted tissue.
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What are the functions of the hypothalamus?
Control of blood flow, regulation of energy metabolism, regulation of reproductive activity, and coordination of responses to threatening conditions.
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Why does the hypothalamus receive input from the visceral motor system and cortex?
The hypothalamus compares what the setpoints should be with what information it is receiving and compares them in the scope of contextual information in higher brain areas.
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What are preganglionic motor neurons and where are they located?
Visceral motor neurons in the spinal cord or brainstem.
Contained in the intermediolateral cell column in the lateral horn of the spinal cord.
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What are the paravertebral/sympathetic chain ganglia?
A ganglia chain that runs the length of the vertebral column.
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What are postganglionic neurons?
Visceral motor neurons outside the spinal cord.
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What is the solitary tract nucleus and what does it do?
The solitary tract nucleus in the medulla receives most of the visceral sensory afferent signals.
These help provide contextual input to the visceral motor system and provide other types of signals to upper motor systems about possible dangerous or relaxing stimuli.
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What is the function of the rostral part of the solitary tract nucleus?
Receives gustatory information and sends that to the appropriate brain centers.
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What is the function of the caudal part of the solitary tract nucleus?
The caudal portion of the solitary tract nucleus receives sensory visceral information and sends it to higher cortical areas. By including higher cognitive structures, emotional processing can be involved in these experiences. The higher cognitive areas also have top-down modulation to the visceral motor system.
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Why are higher brain centers included in sensory visceral information?
By higher cognitive areas having top-down modulation, it is able to modulate bodily responses to different emotional stimuli. This is how we blush to embarrassing experiences or respond to fearful situations.
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What are hormones?
Chemicals that travel through the bloodstream to act on targets.
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What are endocrine glands?
Structures that release hormones into the body.
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What are protein hormones?
A string of amino acids that act as a hormone.
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What are amine hormones?
Modified amino acid hormones.
Also called monoamine hormones.
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What are steroid hormones?
Hormones are based on a cholesterol backbone.
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Which kind of hormones act faster and why?
Protein and amine hormones because they bind to the cell membrane and start a signal transduction pathway.
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Which hormones act slower and why?
Steroid hormones because they pass through the cell membrane and act as transcription factors. This takes longer to have an effect.
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What do steroid cofactors do?
Different compounds expressed in different cells allow steroid hormones to have different effects in different cells.
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Where do steroid hormones have a nongenomic effect?
In neuronal membranes.
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What are receptor isoforms?
Different receptors that bind to the same ligand.
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What are releasing hormones?
Hormones from the hypothalamus that bind to the pituitary gland.
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What are tropic hormones?
Hormones released from the pituitary gland.
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What is the adenohypophysis?
Anterior pituitary.
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What is the neurohypophysis?
Posterior pituitary.
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What is the function of the posterior pituitary?
The posterior pituitary is the way for the hypothalamus to release hormones directly.
The posterior pituitary releases oxytocin and vasopressin (anti-diuretic, inhibiting urine formation).
250
What is the hypophyseal portal system?
The local blood vessels in the anterior pituitary.
251
How is the hypothalamus regulated?
By circulating messages (hormones) in the blood and synaptic input from other parts of the brain.
252
What are the adrenal glands and what are the two main components of it?
Adrenal glands are on top of the kidneys and secrete corticosteroids, which are involved in stress responses.
The adrenal glands are made out of the adrenal cortex (80%) and the adrenal medulla (20%).
253
What is the adrenal cortex controlled by?
The adrenal cortex is regulated by the neuroendocrine system.
254
What is the pathway to release corticosteroids?
Release hormone: Corticotropin-releasing hormone (CRH)
Tropic hormone: Adrenocorticotropic hormone (ACTH)
Endocrine gland: Adrenal cortex in the adrenal gland that releases corticosteroids.
255
What is the pathway to release thyroid hormones?
Release hormone: Thyrotropin-releasing hormone (TRH)
Tropic hormone: Thyroid-stimulating hormone (TSH)
Endocrine gland: Thyroid
256
What is the pathway to release androgen hormones?
Release hormone: Gonadotropin-releasing hormone (TRH)
Tropic hormone: Luteinizing-stimulating hormone (LH) and follicle-stimulating hormone (FSH)
Endocrine gland: Testes
257
What is the pathway to release estrogens and progestins?
Release hormone: Gonadotropin-releasing hormone (GnRH)
Tropic hormone: Luteinizing-stimulating hormone (LH) and follicle-stimulating hormone (FSH)
Endocrine gland: Ovaries
258
What hormone inhibits the release of gonad hormones (androgens, estrogens, and progestins)?
Gonadotropin-inhibiting hormone (GnIH)
259
What is the pathway to produce breast milk?
Release hormone: Prolactin-releasing peptide.
Tropic hormone: Prolactin
Target: Breasts
260
What hormone inhibits breast milk production?
Prolactin-inhibiting factor.
261
What is the hormone pathway that leads to bone growth?
Release hormone: Somatocrinin
Tropic hormone: Growth hormone (GH)
Target: Bones.
262
What hormone inhibits bone growth?
Somatostatin.
263
What does the medial part of the amygdala connect to?
The medial group has large connections to the olfactory bulb and olfactory cortex.
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What does the basolateral group of the amygdala connect to?
The basolateral group has many connections to the basal ganglia, anterior temporal lobe, orbital cortex, and medial prefrontal cortex.
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What does the central group of the amygdala connect to?
The central/anterior portion has connections between the hypothalamus and the visceral motor system.
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What is the function of the amygdala?
The amygdala helps process complex stimuli to express emotion. It invests sensory experiences with emotional significance.
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What does the amygdala do after an emotional experience?
After an emotionally arousing experience, hormones are released which activate the amygdala. The amygdala then helps consolidate these events.
268
What is Kluver-Bucy syndrome?
Kluver-Bucy syndrome can result from damage to the amygdala which disconnects visual stimuli from the appropriate emotional response.
269
What is the affect heuristic?
Emotions triggered by a decision that help people think through the consequences of that decision.
270
Why do we have motivated behavior?
Motivated behavior can be due to reducing a drive (such as hunger), getting a positive reward, or avoiding a negative consequence.
271
What is the function of the VTA?
The VTA helps to predict rewards and anything unexpected that happens with rewards (getting one or not getting one) leads to VTA activity.
272
What kind of rewards do organisms like?
Immediate rewards
Larger rewards
Rewards that you are certain to get
273
What is dopamine’s role in drug addiction?
Drugs of abuse increase dopamine levels.
Dopamine likely helps reinforce drug use.
274
What are psychostimulants and what kinds of drugs do they use?
Psychostimulants are drugs that mimic the activation of the sympathetic nervous system. This includes cocaine and amphetamines.
275
What is the mechanism of action for cocaine and amphetamines?
Blocking or reversing monoamine reuptake.
276
What are opioid's mechanisms of action?
Inhibiting dopamine release in the VTA.
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Why is alcohol seen as a dirty drug?
Alcohol is a dirty drug because you need a much higher concentration to get an effect than other drugs. Then, because it is at such a high percentage, it has many off-target effects.
