CNS/Sensory&Cognitive/Motor Flashcards
1
Q
Motor output:
-from where to where?
-cell bodies where?
A
-From CNS to effectors
-Cell bodies in CNS
2
Q
Sensory input:
- what 2 types of sensory?
-from where to where?
-cell bodies where?
A
-somatic and visceral sensory
-From receptors to CNS
-Cell bodies out of CNS
3
Q
Somatic efferent:
-innervates what?
-type of neurons?
A
-innervates skeletal muscles
-only excitatory (Ach) neurons (motor neurons)
4
Q
Autonomic efferent:
-innervates what?
-type of neurons?
A
-innervates interneurons, smooth and cardiac muscles
-excitatory and inhibitory neurons
5
Q
Spinal nerves:
-2 types of sensations and where do they come from?
A
Somatic sensation:
comes from the receptors of the eyes, ears, nose, tongue and skin
Visceral sensation: comes from the internal organs
6
Q
Brainstem:
3 parts?
A
Midbrain
Pons
Medulla
7
Q
White matter vs gray matter:
-brain vs spinal cord
A
Brain: white matter inside and gray matter on the outside
Spinal cord: white matter outside and gray matter on the inside
8
Q
What do the cervical nerves innervate? (4)
How many pairs?
A
Neck
shoulders
arms
hands
8 pairs
9
Q
What do the Thoracic nerves innervate? (3)
How many pairs?
A
shoulders
chest
upper abdominal wall
12 pairs
10
Q
What do the lumbar nerves innervate? (3)
How many pairs?
A
Lower abdominal wall
hips
legs
5 pairs
11
Q
What do the sacral nerves innervate? (2)
How many pairs?
A
genitals
lower digestive track
5 pairs
12
Q
How many pairs in the Coccygeal nerves?
A
1 pair
13
Q
What enters the dorsal horn?
A
afferent sensory info
14
Q
What exits the ventral horn?
A
efferent motor control neurons
15
Q
The spinal nerve approaches the spinal segments and divides into 2….divides into what and what?
A
divides into:
dorsal root
ventral root
16
Q
What does the dorsal root ganglia contain?
A
cell bodies of the afferents sending sensory info into the spinal cord
17
Q
10 of the 12 cranial nerves connect to the ___________. Cranial nerves have both ___________ and ____________ signals together.
A
brain stem
sensory
motor
18
Q
What is a concussion, and why is it a concern in terms of brain swelling?
A
A concussion is a form of bleeding or swelling in the brain. The concern with a concussion is that excessive brain swelling can lead to increased pressure within the hard skull, potentially pushing the brain out of the base of the skull.
19
Q
Why is the location of the cranial nerves involved in the pupillary reflex significant in the context of head injuries?
A
The location of these cranial nerves is significant because they exit the brain stem at the base of the skull. In cases of brain edema, swelling, or bleeding inside the brain, the brain’s expansion can compress these nerves, impacting the pupillary reflex.
20
Q
Early development of the nervous system
A
Fertilized egg (ovum)
Ball of cells
Blastocyst - week1
Blastocyst - week 2 (+ definition)
Blastocyst - week 3 (embryonic disk
Embryonic disk becomes ectoderm, mesoderm and endoderm.
Formation of neural groove
Formation of neural tube - week 4
21
Q
Neural tube – vesicles
become what ?(4)
A
Forebrain:
Cerebral hemispheres+thalamus
Midbrain:
midbrain
Hindbrain:
cerebellum+pons+medulla
Straight portion:
spinal cord
Cavity:
ventricles+central canal
22
Q
Ectoderm becomes? (2)
A
-neural groove (neural tube)
-nervous system (CNS and PNS)
23
Q
Mesoderm becomes? (2)
A
-muscles and various other body parts start to develop
-the dura
24
Q
Endoderm becomes? (1)
A
digestive system
25
Choroid plexus:
what is it?
what does it do?
-fuzzy lining on the ventricles
-where CSF is produced
26
What is the primary source of production for cerebrospinal fluid (CSF)? (how much vs how much ventricles contain)
primarily produced by the choroid plexus, mainly in the two lateral ventricles, at a rate of approximately 500 ml per day (Ventricles contain 150mL).
27
Name three functions of cerebrospinal fluid (CSF) in the central nervous system (CNS)
1. Supports and cushions the CNS.
2. Provides nourishment to the brain.
3. Removes metabolic waste through absorption at the arachnoid villi.
28
What is the composition of cerebrospinal fluid (CSF) in terms of its appearance and notable components? (5)
-sterile
-colorless
-acellular.
-It contains glucose
- has a specific gravity equal to that of the brain.
29
How does cerebrospinal fluid (CSF) circulate within the central nervous system?
Cerebrospinal fluid circulates passively and is not actively pumped.
30
Explain the CSF circulation steps. (10)
1. Choroid plexus
2. Lateral ventricles
3. intraventricular Foramens (Foramen of Monro)
4. Third ventricle
5. Fourth ventricle
6. Foramen of Lushka & Foramen of Magendie
7. Subarachnoid space
8. Arachnoid villi
9. Dural sinus
10. Venous system
31
What are the 3 meninges of the CNS?
Dura mater: The outermost and toughest layer, the dura mater, provides protection and support for the brain and spinal cord. It is a thick, durable membrane that surrounds the CNS.
Arachnoid membrane: The middle layer, the arachnoid mater, is a thin and delicate membrane that lies beneath the dura mater. It helps cushion the CNS and contains cerebrospinal fluid (CSF), which circulates around the brain and spinal cord.
Pia mater: The innermost layer, the pia mater, is a thin, vascular membrane that directly adheres to the surface of the brain and spinal cord. It provides nutrients to the nervous tissue and is closely connected to the underlying neural structures. Contains Trabeculae, that are thin, connective tissue strands that extend from the pia mater into the underlying neural tissue, providing structural support and anchoring the pia mater to the CNS.
32
Where does CSF return to the blood?
Dural sinus
33
What is supplied to the brain by the blood?
-Glucose is usually the only substrate metabolized by the brain.
-Very little glycogen in the brain.
--Brain needs a continuous supply of glucose and oxygen (glucose transport into the brain does not require insulin).
34
A few seconds of blood supply interruption can lead to...
and a few minutes...
loss of consciousness
neuronal death (stroke)
35
How much blood % does brain receive?
Brain receives 15% of total blood (but is 2% of total mass)
36
Explain the circle of Willis.
The aorta branches into the common carotid which branches into internal carotids. Behind the internal carotids, we have the vertebral arteries, that join to make the basilar artery. They all join to form the circle of Willis. This acts as a safety factor, which means that if one of your internal carotid arteries or the vascular artery or something is blocked and not providing enough blood, this allows blood from the functioning side to be shunt over because you have to keep the blood flow to your brain.
37
What is the blood-brain barrier, and why is it significant for drug delivery to the brain?
The blood-brain barrier is a protective mechanism in the central nervous system that limits the passage of substances from the blood into the brain. It is crucial for drug delivery because it regulates which substances can enter the brain, impacting the efficacy of medications.
38
How do the endothelial cells in the central nervous system differ from those in other parts of the body?
Endothelial cells in the central nervous system have tight junctions, which make them impermeable to most substances. This is in contrast to endothelial cells in other parts of the body, which typically have openings or junctions allowing substances to flow through.
39
What role do astrocytes play in the blood-brain barrier?
Astrocytes are glial cells that help induce the tight junctions between endothelial cells in the blood-brain barrier. They provide structural support and assist in regulating ionic concentrations and maintaining an environment suitable for proper neuronal function.
In addition, Astrocytes, a type of glial cell, provide structural support, regulate ionic concentrations, and maintain a suitable environment for neurons to function correctly in the central nervous system.
40
How can substances cross the blood-brain barrier?
by being lipid-soluble
passive diffusion or active transport
41
Name some examples of lipid-soluble substances that can easily cross the blood-brain barrier.
water, oxygen, carbon dioxide, caffeine, and alcohol.
42
Why does morphine cross the blood-brain barrier slowly, while heroin, derived from morphine, can enter the CNS more rapidly?
Morphine crosses the blood-brain barrier slowly due to its limited lipid solubility. Heroin is chemically modified to enhance its ability to cross the barrier and then reverts to morphine once inside the CNS, preventing it from exiting.
43
What challenges does the blood-brain barrier pose for drug delivery to the central nervous system?
The blood-brain barrier makes it difficult for drugs to reach the brain, which can be a challenge in treating conditions like brain cancer or infections. Ions and large protein molecules typically do not pass the barrier unless actively transported.
44
What substances are actively transported into the brain across the blood-brain barrier?
Glucose and specific amino acids are actively transported into the brain through the blood-brain barrier.
45
What is the difference between sensation and perception?
Sensation is the awareness of sensory stimulation, while perception is the understanding of the meaning of a sensation.
46
Do we directly perceive the "energy" of a sensory stimulus?
No, we do not directly perceive the "energy" of a sensory stimulus. Instead, we perceive the neural activity that is produced by sensory stimulation.
47
What is the Law of Specific Nerve Energies?
The Law of Specific Nerve Energies states that regardless of how a sensory receptor is activated, the sensation felt corresponds to what the receptor is specialized for. For example, rubbing your eyes hard can lead to the sensation of seeing light.
48
What is the Law of Projection in sensory perception?
The Law of Projection states that regardless of where in the brain you stimulate a sensory pathway, the sensation is always felt at the sensory receptor's location. For example, when Penfield electrically stimulated the somatic sensory cortex, patients perceived somatic sensations in their body.
49
Can you provide an example of the Law of Projection in action?
An example of the Law of Projection is phantom limb pain after amputation. Even though the limb is no longer present, the sensation is still felt as if it were, illustrating how sensory perception can project sensations to their original location.
50
What is meant by the term "modality" in sensory perception?
Modality refers to the general class of a stimulus. It describes the type or category of sensory input, such as vision, hearing, touch, taste, or smell.
51
What does the term "labeled-line" mean in the context of sensory perception?
In a labeled-line system, the brain "knows" the modality and location of every sensory afferent. Each sensory pathway is specifically labeled to convey information about the type of stimulus and where it is coming from.
52
What are sensory receptors?
Sensory receptors are specialized cells or structures in the body that detect and respond to a precise/adequate sensory stimuli.
53
What is transduction in the context of sensory perception?
Transduction is the process by which sensory receptors convert stimulus energy into neural activity by the opening and closing of ion channels, that can be transmitted to the brain for interpretation.
54
What are afferents in the context of sensory perception?
Afferents are nerve fibers or neurons that transmit sensory information from the sensory receptors to the central nervous system.
55
How does the intensity of a sensory stimulus affect the afferent response?
By determining the magnitude of the receptor potential (stimulus gets stronger and potential gets stronger), which in turn affects the frequency of action potentials generated in the sensory neuron, which will affect the magnitude of neurotransmitter release
56
What is adaptation in the context of afferent responses?
Adaptation is the process by which afferent sensory neurons change their response to a stimulus over time, either by decreasing or increasing their activity.
57
Why do the majority of afferents show adaptation?
Most afferent neurons exhibit adaptation to enable us to be sensitive to changes in sensory input. It helps filter out continuous or unchanging stimuli, allowing the sensory system to focus on new or evolving information.
58
What is the role of non-adapting afferents?
Non-adapting afferents encode stimulus intensity and slow changes. They provide a constant representation of the stimulus and do not reduce their response over time.
59
What do slowly adapting afferents respond to?
Slowly adapting afferents respond to some stimulus intensity and make moderate changes in the stimulus.
60
What is the characteristic of rapidly adapting afferents?
Rapidly adapting afferents are specialized to detect fast stimulus changes. They quickly decrease their response to a continuous or unchanging stimulus but rapidly increase their activity when the stimulus changes.
61
What is a Receptive field (RF)?
The region in space that activates a sensory receptor or neuron.
62
How do receptive fields of sensory neurons typically relate to one another?
Receptive fields often overlap, meaning they cover adjacent areas in sensory space.
Overlapping receptive fields allow sensory neurons to produce a population code.
63
What does overlapping receptive fields contribute to in sensory processing?
Overlapping receptive fields contribute to the generation of a population code, where the combined activity of multiple neurons encodes complex sensory information.
64
What is stimulus acuity, and how does receptive field size relate to it?
Stimulus acuity is the ability to differentiate one stimulus from another. Smaller receptive fields are associated with higher acuity, as they provide more precise information about the location and properties of stimuli.
65
How does lateral inhibition sharpen sensory acuity?
Lateral inhibition is a neural mechanism where the activity of one neuron inhibits the activity of neighboring neurons. This mechanism sharpens sensory acuity by enhancing the contrast between activated and non-activated neurons in response to a stimulus.
66
How do descending pathways influence sensory inputs in the nervous system?
Descending pathways are neural pathways that modulate sensory inputs. They provide "top-down" control, allowing higher brain regions to influence and shape sensory information processing, in addition to the "bottom-up" processing from sensory receptors.
67
What are the key features of touch receptors in the superficial layers of the skin? (2)
Touch receptors in the superficial layers include:
-Merkel disks (slowly adapting, pressure and texture) and
-Meissner's corpuscles (rapidly adapting, light stroking and fluttering).
68
What are the key features of touch receptors in the deep layers of the skin? (2)
Touch receptors in the deep layers include
-Pacinian corpuscles (rapidly adapting, strong vibrations) and
-Ruffini endings (slowly adapting, stretch, and bending of the skin, shape of an object).
69
How do proprioceptors, such as muscle spindles, contribute to somatic sensation? (function)
Proprioceptors, like muscle spindles, provide a sense of the static position and movement of limbs and the body. They help us maintain balance and control our movements.
70
How do thermoreceptors respond to temperature variations, and what are the temperature ranges they detect?
Thermoreceptors are free nerve endings containing ion channels. Cold afferents respond to temperatures between 0°C and 35°C, while warm afferents respond to temperatures between 30°C and 50°C. Extreme temperatures activate pain receptors.
71
What are nociceptors, and how do they respond to different types of stimuli?
Nociceptors are free nerve endings that respond to intense mechanical deformation, excessive temperature, or chemicals. They are highly modulated, both enhanced and suppressed, to regulate pain perception.
72
What activates visceral pain receptors?
Visceral pain receptors are activated by inflammation.
73
Explain the enhancement of nociceptors leading to hyperalgesia.
1. Damaged cells
2. Nociceptors send AP to spinal cord.
3. Substance P is released in spinal cord
4. Enhancement of surrounding nociceptors by injured tissue (chemicals) & afferent feedback onto mast cells which will release histamine
5. Dilation of nearby blood vessels
74
What is hyperalgesia?
an increased sensitivity to pain
75
What are the primary sensory modalities carried by the dorsal column pathway?
touch and proprioception.
76
Describe the steps of the dorsal column pathway from the receptors to the cortex.
1. Receptors
2. Spinal nerve-- through the dorsal root ganglion
3. Signals ascend the spinal cord via the dorsal columns (ipsilateral)
4. Synapse in the medulla (ipsilateral)
6. Crosses the midline
6. synapse in thalamus (Contralateral)
7. Project to somatosensory cortex (Contralateral)
77
Describe the steps of the Anterolateral pathway from the peripheral receptors to the cortex.
1. Receptors
2. Spinal nerve-- through the dorsal root ganglion
3. Signals enter the spinal cord, in the gray matter (dorsal horn) (ipsilateral)
4. Synapse in the spinal segment (gray matter) (ipsilateral)
5. Cross mid-line at the central canal
6. Signals ascend through the anterolateral column (Contralateral)
7. Branches into the reticular formation
8. Synapse in the thalamus (Contralateral)
9. Project to somatosensory cortex (Contralateral)
78
What is a somatotopic map in the context of the brain? (+which body parts from lateral to medial)
A somatotopic map is a representation of the body's surface on the cortex, where different areas of the brain correspond to specific body parts. Each body part is mapped to a specific location in the brain.
On a contralateral representation of somatosensory cortex, from lateral to medial: Head, arms, legs
79
How are mechanoreceptors activated?
By stretching the cytoskeleton strands. They are open by the cytoskeleton strands that connect the ion channels that are in the membrane of the the nerve ending.
80
What is referred pain due to?
Visceral & somatic pain afferents commonly synapse on the same neurons in the spinal cord.
The spinal segment doesn't know which afferent is driving the pain. Brain usually assigns it to the skin (somatic afferent).
81
Explain the Descending pathways that regulate nociceptive information
(analgesia)
It is a top down mechanism.
The afferent drives the info through the anterolateral pathway (contralateral). But there is a neuron starting in the Periaqueductal gray matter (midbrain), then synapsing in the Reticular formation (medulla), following the Dorsolateral funiculus, allowing to inhibit the synapse of the afferent in the dorsal horn. This allows to reduce the release of substance P, and shut off the perception of pain.
82
Analgesia stops the release of substance P thanks to...
Opiate neurotransmitters
(presynaptic inhibition)
83
In the eye, what is the fovea centralis?
highest visual acuity
84
In the eye, what is the optic disk?
blind spot
85
In the eye, what is the sclera?
white portion of eye
86
What is the primary function of a lens in the eye?
A lens refracts (bends) light to a single point, aiding in focusing light onto the retina for clear vision.
87
Which eye structures are responsible for the refraction of light?
Light is refracted by both the cornea and lens to facilitate proper vision.
88
the cornea or the lens, which structure refracts light to a greater degree?
The cornea refracts light more significantly than the lens.
89
What happens during accommodation for near vision?
Accommodation for near vision involves adjusting the lens shape via the ciliary muscles
90
What is myopia? Corrected?
Myopia (nearsightedness) results in difficulty seeing distant objects. Corrected with divergent lens.
91
What is hyperopia? Corrected?
hyperopia (farsightedness) causes trouble focusing on close objects. Corrected with convergent lens.
92
What is astigmatism?
Astigmatism occurs when the lens or cornea is not spherical
93
What is presbyopia?
Presbyopia occurs when the lens stiffens, making it unable to accommodate for near vision, particularly as one ages.
94
What is a cataract?
Cataracts involve changes in the lens color, that result in a cloudy or discolored appearance
95
What role do ganglion cells play in the visual process?
Ganglion cells collect information from bipolar cells and send it to the brain via the optic nerve.
96
What structure does the combination of axons from ganglion cells form, facilitating the transmission of visual information to the brain?
The optic nerve
97
Explain the GENERAL transduction in the organization of the retina (4 steps)
-Transduction (rods and cones)
-Change in neurotransmitter release
-Processing and convergence (bipolar cells, horizontal cells and amacrine cells)
-Becomes optic nerve
98
How does the light reach the rods and cones in the fovea centralis if there are other cells in the way?
In fovea centralis, the retinal circuitry is shifted out of the way
99
Explain phototransduction. (5)
In the outer segment of rods (and cones):
1. Light activates opsin molecule (rhodopsin in rods) which has chromophore in it. This causes a conformational change, resulting in the separation of the opsin and the chromophore.
2. This triggers a G-protein cascade
3. cGMP is converted into GMP
4. The cGMP-gated channels close
5. Which stops the neurotransmitter release, usually releases in the dark
100
Light causes photoreceptors to depolarize or hyperpolarize?
Hyperpolarize
101
Name the differences between rods and cones (5) and the 2 differences between the 2 systems
-Rods:
High sensitivity, night vision
More rhodopsin, captures more light
High amplification, single photon closes many Na+ channels
Slow response time
More sensitivity to scattered light
-Rod system:
Low acuity: not present in central fovea, highly convergent
Achromatic: one type opsin
-Cones:
Low sensitivity, day vision
Less opsin
Lower amplification
Faster response time
Most sensitive to direct axial rays
-Cone system:
High acuity: concentrated in fovea, less convergent
Chromatic: three types of opsin
102
Describe the process of dark adaptation.
In bright light, rods are inactivated, and cones are active. In darkness, there's temporary blindness until rods "re-activate" and take over, allowing for better vision in low-light conditions.
103
Describe the process of light adaptation.
In darkness, cones are inactive, and rods are active. In bright light, rods are initially saturated, causing temporary blindness until rods "inactivate," and cones, adapted for bright conditions, take over for clearer vision.
104
Explain why light/dark adaptation takes time.
Light breaks the bond between the opsin and the chromophore and it takes time to put them back together. To get put back together, they have to pass by the retinal pigment epithelium and it's a slow process.
105
What are the characteristics of the receptive fields of retinal ganglion cells? (+/-)
Retinal ganglion cells possess center-surround receptive fields, enabling them to detect and process contrast or relative differences in light across their visual fields.
106
What computation do retinal ganglion cells perform?
Retinal ganglion cells compute the relative differences in light intensity across their receptive fields.
107
Retinal ganglion cells with an excitatory center would send a higher frequency of action potential if they perceive a _______ center and a ________ surround. Retinal ganglion cells with an inhibitory center would send a higher frequency of action potential if they perceive a _______ center and a ________ surround.
Bright
Dark
Dark
Bright
108
What characteristic determines a photoreceptor's sensitivity to different colors?
Wavelength sensitivity
109
What specific component in photoreceptors influences their ability to perceive color?
Opsin molecules
110
How do retinal ganglion cells process color information?
These cells have receptive fields that respond to color in an opposing manner, emphasizing differences between certain hues to create a more distinct color perception. ( color opponent receptive fields) (Red&green or blue&yellow)
111
What kind of information does the retina convey to the brain regarding visual stimuli?
The output of the retina encodes relative values of brightness and color
112
What condition results in an individual being unable to distinguish certain colors?
Color blindness is a vision impairment that causes difficulty in differentiating specific colors or seeing them at all due to deficiencies in the photoreceptors responsible for color perception.
113
Explain the flow of visual information in the brain.
1. **Step 1: Capture of Visual Information**
- Visual information from the right visual field is received by the left half of each retina.
2. **Step 2: Optic Tract Formation**
- Fibers carrying information from the left half of the retinas of both eyes converge to form the right optic tract, containing data from the right visual field of both eyes.
3. **Step 3: Optic Nerve Transmission**
- The optic nerve from each eye carries information from both the left and right visual fields of that eye.
4. **Step 4: Optic Chiasm**
- At the optic chiasm, some optic nerve fibers from each eye cross over to the opposite side, allowing integration of visual information from both eyes and both visual fields.
5. **Step 5: Processing at the Lateral Geniculate Nucleus (Thalamus)**
- The optic tract fibers synapse at the lateral geniculate nucleus (LGN) within the thalamus, acting as a relay station to sort and direct visual information.
6. **Step 6: Transmission via Optic Radiations**
- Visual information travels through the optic radiations, nerve pathways that carry signals from the LGN to the visual cortex.
7. **Step 7: Visual Cortex Processing**
- The visual cortex, situated in the occipital lobe, receives and processes visual information from both eyes and both visual fields. The right visual cortex processes left visual field information, and the left visual cortex processes right visual field information.
114
What term describes the integration of visual information with other sensory inputs?
The term "polymodal" refers to the combining of visual information with other sensory modalities, resulting in a more comprehensive perception.
115
What characteristics define the processing in the parietal visual stream?
known as the "Where" pathway, specializes in processing large receptive fields (RFs), spatial features, and motion in the visual field.
116
What distinguishes the primary visual cortex in terms of receptive fields and processed features?
The primary visual cortex handles small receptive fields (RFs) and processes simple visual features like oriented line segments.
117
Which stream in the brain, termed the "What" pathway, deals with visual processing?
The temporal visual stream
118
What two characteristics define a sound wave?
Frequency= number of cycles/second= pitch
amplitude=loudness
119
What is something special about the damage threshold?
The threshold of damage was inferior than the pain threshold.
120
What is the term for age-related hearing loss?
Presbycusis
121
In the anatomy of the ear, what is the pinna? (2)
-visible external part of the ear
-reflects certain frequencies into auditory canal
122
In the anatomy of the ear, what are the 3 bones?
Malleus, incus & stapes
123
In the anatomy of the ear, what is the eustachian tube?
Narrow canal that connects the middle ear to the pharynx (the upper part of the throat behind the nose).
124
Explain the flow of sound energy in steps including the transduction process
1. Sound waves enter the outer ear.
2. Travel through the external auditory canal.
3. Reaching the eardrum (tympanic membrane).
4. Vibration of the eardrum.
5. Transmission through the ossicles.
6. Oval window vibration.
7. Fluid movement in the cochlea.
8. The cochlea contains the basilar membrane, which is lined with the organ of Corti.
9. Hair cell stimulation begins when the stereocilia are displaced by the movement of the fluid in the cochlea.
10. Tip links, which connect each stereocilium to its neighbor, respond to the mechanical displacement.
11. The deflection of the stereocilia produces shearing forces, leading to the opening of ion channels in the hair cell membrane.
12. Ion influx generates electrical signals in the hair cells.
13. Auditory nerve transmission carries the electrical signals to the brain.
14. Sound perception occurs in the auditory cortex, where the brain interprets the signals into the perception of sound.
125
What modulates amplification in the ear?
Amplification in the ear is modulated by skeletal muscles.
126
How is the motion of the basilar membrane related to frequency?
The motion of the basilar membrane is frequency-dependent, with low frequency at the tip of the cochlea and high frequency closer to the oval window.
127
What is the function of the round window?
As fluid moves in the cochlea due to the sound waves, the round window flexes outward to release the pressure generated by these movements.
128
Where is the conversion of basilar membrane motion into neuronal activity?
The conversion of basilar membrane motion into neuronal activity occurs at the organ of Corti.
129
What occurs when the basilar membrane deflects, producing shearing of hair cell stereocilia?
transduction
130
What connects each stereocilia on hair cells?
Tip links
131
What are the two main types of hair cells in the organ of Corti?
inner hair cells and outer hair cells.
132
What is responsible for gating ion channels in hair cell stereocilia?
Tip links gate ion channels in hair cell stereocilia.
133
What is the role of mechanoreceptors in hair cells?
Hair cells contain mechanoreceptors that respond to mechanical stimuli, such as the movement of stereocilia.
134
What activates afferent neurons at tip links?
Mechano-transduction at tip links activates afferent neurons, transmitting signals to the brain.
135
Why does the transduction at the tip links allow the flowing in of K+ and not Na+?
The fluid of the Cochlea is different from the ECF, it is high in K+. To depolarise, we allow the opening of K+ channels.
136
Give the 4 differences between the Visual and Auditory transductions
Visual:
1. Photons: high energy but hard to catch (~100X106 photoreceptors)
2. Trillions of opsin molecules
3. Slow: G-protein cascade
4. Amplification: one photon closes many ion channels
Auditory
1. Sound waves: low energy but all around (~15,000 hair cells)
2. Several hundred thousand tip links
3. Fast: direct channel activation
4. No amplification of the transduction
137
Can you explain the central auditory pathways.
1. Vestibular and auditory signals are carried by the 8th cranial nerve.
2. Synapse at the medulla
3. Some fibers cross to the opposite side (contralateral) while others remain on the same side (ipsilateral). (BILATERALLY represented)
4. Synapse at the midbrain
5. Synapse at the thalamus
6. Projects to the primary auditory cortex
138
Name the vestibular organs and their function (3)
1. Three semi-circular canals: Angular acceleration
2. Utricle: Linear acceleration (Horizontal)
3. Saccule: Linear acceleration (vertical)
139
Explain the vestibular ocular reflex.
When you turn your head, the fluid-filled canals in your inner ear (vestibular system) sense the movement. The brain quickly processes this information and sends signals to the eye muscles. These signals cause your eyes to move in the opposite direction of your head, allowing you to keep a steady gaze on a fixed point even while your head is in motion. This reflex helps prevent blurring of the visual field and contributes to our ability to see clearly during activities like walking or turning our heads.
140
Explain the organization of semicircular canals (3)
Ampula:
At one end of each semicircular canal, there's a dilation called the ampulla.
Cupula:
Inside the ampulla, there is a gelatinous structure called the cupula.
Stereocilia:
Hair cells with tiny hair-like projections called stereocilia are embedded in the cupula.
141
Explain how the semicircular canals work
When you move your head, the fluid in the semicircular canals also moves, causing the cupula to bend.
The movement of the cupula bends the stereocilia on the hair cells.
This bending of stereocilia open ion channels, generating action potentials that are transmitted to the brain.
The brain interprets these signals to understand the direction and speed of your head movement
142
Explain the concept of motion sickness and dizziness, due to these semicircular canals
Motion sickness and dizziness can be attributed to a conflict between visual input and signals from the semicircular canals, which are sensitive to head movements. The fluid in these canals has inertia, meaning it doesn't immediately adjust to sudden changes. For example, when reading in a moving car, your eyes may see a stationary environment, but the fluid in the semicircular canals continues to move, causing a mismatch that leads to motion sickness. Dizziness can result from disruptions in the balance signals when the fluid's inertia is challenged by rapid or prolonged movements.
143
Explain how the utricle and saccule detect linear acceleration
Inside the utricle and saccule, there are tiny ear stones called otoliths. When you experience linear acceleration, the otoliths move (lags behind) due to the fluid's inertia. This movement bends hair-like projections (stereocilia) on hair cells, opening ion channels, generating signals that travel to the brain.
144
Where are taste cells located?
On tongue
In papillae
In taste pore
In taste buds
In taste cell
145
How does the salty taste transduction occur?
Salty taste transduction involves the detection of sodium ions (Na+) by ion channels on the taste receptor cells selective for Na+.
146
What activates the sour taste receptors? (transduction)
Sour taste receptors are activated by the presence of acidic substances, which lead to the influx of hydrogen ions (H+).
147
How does the bitter taste transduction occur? (2 ways)
1. Bitter taste transduction involves the activation of G-protein-coupled receptors, leading to a signaling cascade and opening/closing of ion channels.
2. bitter substances can block K+ channels
148
How does the presence of Na+ or K+ ions affect the perception of sour taste?
The presence of Na+ ions can enhance the perception of sour taste, while the presence of K+ ions can block or reduce the sensation of sourness.
149
How does the sweet taste transduction occur?
Sweet taste transduction is mediated by the activation of G-protein-coupled receptors on taste receptor cells, leading to a signaling cascade and opening/closing of ion channels.
150
How does the umami transduction occur?
Umami taste transduction involves the binding of glutamate to glutamate receptors on taste cells, leading to the activation of G-protein-coupled receptors and the initiation of a signaling cascade, ultimately resulting in the perception of umami.
151
Describe the central taste pathways
The taste buds send taste afferents which become the cranial nerves into the medulla, where it synapses. Then it send the signal to the thalamus, synapses, and then projects to the ipsilateral gustatory cortex.
**doesn't cross the midline**
152
Describe the organization of the olfactory system, (broad, general)
The olfactory system is organized into several key components. The olfactory epithelium, located in the nasal cavity, contains olfactory receptor cells responsible for detecting odors. These cells transmit signals through the olfactory nerve to the olfactory bulb, where initial processing occurs. From the olfactory bulb, information travels along the olfactory tract to higher brain centers, contributing to the perception of smell.
153
Outline the process of olfactory transduction
Olfactory transduction begins with odorant molecules binding to specific receptors, oderant receptors. This binding activates G-proteins, triggering a cascade of intracellular events. As a result, ion channels, open, allowing the influx of ions. This influx of ions generates an electrical signal, which is then transmitted to the olfactory bulb and further processed in the brain to perceive the smell.
154
Explain the phenomenon of being able to perceive a vast number of odors despite having around 1000 different odorant receptors in the olfactory system.
each receptor is capable of responding to multiple odor molecules, and conversely, a single odorant can bind to multiple receptors
155
Identify the brain region to which the olfactory system directly projects
Directly: Primary olfactory cortex
(But also the limbic system in the brain, but not directly )
156
What is the state of consciousness, and how is it assessed?
The state of consciousness refers to the level of arousal, whether one is awake, asleep, etc. It is measured by observing behavior and analyzing brain activity.
157
Define conscious experience and provide examples.
Conscious experience involves thoughts, feelings, desires, and ideas. It is the capacity to experience one's existence beyond automatic responses. Examples include subjective mental processes.
158
How is consciousness distinguished from mere responsiveness to stimuli?
Consciousness involves the capacity to experience one's existence, while responsiveness to stimuli is more automatic. It goes beyond recording and reacting, reflecting a mental life.
159
What is the role of the electroencephalograph (EEG) in measuring consciousness?
The EEG mainly measures the activity of neurons near the scalp in the gray matter of the cortex. It provides insights into brain activity associated with different states of consciousness.
160
How is the frequency of EEG related to levels of responsiveness, and what does amplitude reflect in EEG measurements?
The frequency of EEG is related to levels of responsiveness, where slow frequencies, such as alpha rhythm during relaxed eyes closed states, indicate lower responsiveness. Or for example, beta rhythm are associated with alert mental states.
The amplitude is related to synchronous neural activity.
161
Describe the four non-REM sleep stages and the REM stage in terms of EEG patterns, including characteristics such as amplitude, frequency, and duration.
Awake is low amplitude and high frequencies. Stage 1 is low amplitude and high frequency and it take 30-45min to travel to stage 4 and takes the same amount to travel back to stage 1 (cycle). As you move from stage 1 towards stage 4, you have lower amplitudes and higher frequencies. While sleeping, you can jump into REM, which is low amplitude and high frequencies.
162
Can you name the 3 physiological changes during sleep, more specifically during the REM sleep?
Increased eye movement
Increased inhibition of skeletal muscle (low muscle tone, but twitching can occur)
Increased heart rate and respiration
163
What is sleep apnea?
Sudden reduction in respiration
(Mechanical problem: tongue falls back and blocks (snoring), which is not bad but it can interrupt REM sleep, which can be bad bcz we wake up if respiration is decreased)
164
What is the circadian rhythm? Mediated by?
The circadian rhythm is the natural, internal process that regulates the sleep-wake cycle.
Reticular activating system
Pre optic area of hypothalamus
Suprachiasmatic nucleus of the hypothalamus
These areas project everywhere in the brain.
165
Can you explain the regulation of states of consciousness/sleep with the neurotransmitters involved. (Diagram)
Brain stem nuclei that are a part of the reticular activating system allow to :
- ↑norepinephrine and serotonin & ↓acetylcholine = WAKING
(Aminergic neurons are active)
Or
- ↓ norepinephrine and serotonin & ↑acetylcholine = SLEEP
(Cholinergic neurons are active)
Hypothalamus with circadian and homeostatic centers allows to:
- ↓ GABA + ↑Histamine + ↑activation of thalamus and cortex = WAKING
Or
- ↑ GABA + ↓ Histamine + ↓ activation of thalamus and cortex = SLEEP
(Increased inhibition)
166
What is motivation? And what are emotions?
Motivation: produce goal directed behavior
Emotions: accompany our conscious experiences
167
What is the Mesolimbic dopamine pathway?
+ explain the pathway
Pathway that guides a lot of our behaviour, referred as our reward pathway: it is a part of CNS that evaluates reward vs punishment
The transmitters in this pathway are transmitters can be mimicked by drug of abuse.
Dopamine is the primary neurotransmitter (Amphetamines)
Activating the Locus ceruleus in the reticular activating system,
which projects into the Midbrain
which then projects into the prefrontal cortex
168
What is the Limbic system and what are the 3 structures included viewed in class?
Involved in emotions and memory. (Sensory inputs that generate strong emotional responses tend to be the ones we remember the most)
- Olfactory bulb
- Amygdala
- Hippocampus (memory)
169
Can you briefly explain the Altered states of consciousness as Schizophrenia, Depression and Bipolar disorder (and the treatments we discussed)?
Schizophrenia: excess of dopamine. diverse set of problems in basic cognitive processing. Wide range of symptoms including hallucinations and delusions. Affects one out of 100 people.
Reducing the effects of dopamine can improve symptoms.
Mood disorders:
Depression - decreased activity in the anterior limbic system.
Treatments increase the levels of serotonin and norepinepherine in the extracellular space around synapses.
Bipolar disorder - swings between mania and depression.
Treatments include lithium that reduces certain synaptic signaling pathways.
170
Explain the difference between declarative memory and procedural memory and where it is stored.
Declarative:
Conscious experiences that can be put into words
Short term: hippocampus and other temporal lobe structures
*consolidation*
Long-term: many areas of association cortex
Procedural:
Skilled behavior
Short term: widely distributed
*consolidation*
Long term: Basal nuclei, cerebellum, premotor cortex
171
What is the correlation with sleep and memory?
A lot of consolidation from short-term to long term memory happens during sleep.
172
Can you explain the 2 language related regions and how a damage in one of them can affect the individual.
Broca's area: articulation/production of language
damage: understand but can't produce language
Wernicke's area:
comprehension of spoken/written language
damage: unable to comprehend but can produce words but those make no sense.
173
What is the language deficit called?
Aphasia
174
Where is language presented in the brain?
Only in one cortex
90% of times it is presented in the left cortex
175
What is the primary consequence of parietal damage?
Parietal damage often leads to sensory neglect, a condition where individuals ignore stimuli from one side of their environment.
176
Identify and distinguish between the two types of motor behavior.
Voluntary: Intentional, under conscious control, and typically involves planning and coordination.
Reflexive: Involuntary, automatic responses to stimuli, often for the purpose of protection or maintaining balance.
177
Explain the concept of muscle control and its role in movement.
Muscle control involves the activation and coordination of muscles to produce movement. It includes:
Extension vs. Flexion: Extension increases the angle around a joint, while flexion decreases it.
Agonist vs. Antagonist: Agonist muscles are responsible for movement, while antagonist muscles oppose or resist that movement.
178
How are interneurons in the gray matter of the spinal cord activated?
Ascending sensory information (dorsal columns) and Descending motor commands innervate interneurons which drive the motor neurons out of ventral root to innervate muscles.
179
Where do interneurons receive input from? (other than ascending/descending pathway) (6)
- Tension monitoring
- Pain
- Proprioceptive feedback
- Voluntary movements
- Coordinates complex movements
- Length monitoring
180
What is the primary purpose of the withdrawal reflex?
The withdrawal reflex is designed to protect limbs from injury.
181
What is the main function of the stretch reflex, and what are its two subtypes?
The stretch reflex primarily controls muscle length.
It has two subtypes:
a) Monosynaptic (primary) stretch reflex: Involves a direct connection between sensory and motor neurons
b) Polysynaptic (secondary) stretch reflex: Involves interneurons in addition to sensory and motor neurons
182
What is the purpose of the inverse stretch reflex?
The inverse stretch reflex is responsible for controlling muscle tension.
183
How can reflexes be modified?
Most spinal reflexes can be overridden or inhibited by higher brain centers, allowing for voluntary control and adaptation to different situations.
184
Explain the flexion withdrawal reflex.
(also explain the cross extensor refkex)
It is polysynaptic reflex.
The activation of nociceptors drives action potential to the anterolateral columns.
But they also innervate interneurons in the spinal cord, which allow for the inhibition of motor neurons innervating the ipsilateral extensor; and the excitation of motor neurons innervating the ipsilateral flexor.
The other leg has to take the weight of the body and hence we have the cross extensor reflex.
The ascending pathway also leads to the the inhibition of motor neurons innervating the contralateral flexor; and the excitation of motor neurons innervating the contralateral extensor.
185
What factor determines the magnitude of the withdrawal reflex?
The magnitude of the withdrawal reflex is dependent on the magnitude of the pain stimulus.
186
What is irradiation in the context of the withdrawal reflex?
Increase in rate and magnitude of withdrawal response with
increased stimulus strength (recruitment).
187
How do feedback loops in the spinal cord contribute to the withdrawal reflex?
Feedback loops in the spinal cord contribute to the withdrawal reflex by allowing to keep the withdrawal
188
What is afterdischarge in the context of the withdrawal reflex?
Response maintained after stimulus termination (spinal
feedback loops).
189
Explain the monosynaptic stretch reflex (knee jerk)
Knee jerk:
There are some tendons that attache the Patella bone (kneecap) to the other leg bones. And there is a tendon that attaches the Patella to the extensor muscle.
So a tap on the tendon, pull this extensor muscle and it activates stretch receptors (proprioceptive inputs) (inside the muscle).
The were will be ascending pathway towards the ipsilateral dorsal columns that will tell the brain that the muscle length is changing, and this ascending pathway will also innervate the excitatory motor neuron and interneurons in the spinal segment which will lead to inhibition:
1. excitation of motor neurons innervating the ipsilateral extensor (monosynaptic)
2. the inhibition of motor neurons innervating the ipsilateral flexor. (polysynaptic)
Result= you kick
190
What is the structure of a muscle spindle?
A muscle spindle is a specialized stretch receptor located within the muscle belly. It consists of intrafusal muscle fibers, which are surrounded by extrafusal muscle fibers, sensory nerve endings (afferent fibers), and motor nerve endings (efferent fibers). Intrafusal muscle fibers are activated by gamma motor neurons and extrafusal muscle fibers are activated by alpha motor neurons.
191
Where are Golgi tendon organs typically located?
Golgi tendon organs are located at the junction between a muscle and its tendon (attach muscles to bone)
192
What is the primary function of Golgi tendon organs?
Golgi tendon organs monitor changes in muscle tension or force. They provide feedback to the central nervous system about muscle contraction intensity, helping to prevent excessive force and protect the muscle and tendon from damage.
193
How are muscle spindles and extrafusal muscle fibers arranged?
arranged in parallel
194
What are stretch receptors and how are they arranged?
They are proprioceptive receptors that measure the length of the muscle
Arranged in parallel with muscle fibers
195
How is the Golgi tendon organ positioned in relation to muscle fibers?
The Golgi tendon organ is positioned in series with muscle fibers, at the junction between a muscle and its tendon. This series arrangement allows the Golgi tendon organ to sense changes in muscle tension and provide feedback to prevent excessive force.
196
Summarize the organization of a muscle spindle, including its key components.
A muscle spindle consists of intrafusal muscle fibers (organized as nuclear bag and chain fibers), a connective tissue capsule for structural support, sensory (afferent) nerve fibers (1a and II fibers) for stretch detection, and motor (gamma efferent) nerve fibers for adjusting spindle sensitivity.
197
What is the difference between 1a primary and II secondary afferents?
Ia primary: signal dynamic changes in muscle length (and some static length)
II secondary: signal static muscle length
For example: during a linear stretch, 1a will fire AP really fast during stretch and then slow down, but II are slower to respond will increase response when the stretch is over and back o steady state.
During tap stretch reflex, only 1a sense the tap and fire AP, II don’t even see it.
198
Explain the loss of sensitivity in muscles spindles
Normal Sensitivity: In a resting state or when the muscle is lengthening (stretching), the muscle spindle is appropriately stretched, and its stretch receptors are activated. This activation leads to the generation of action potentials that convey information to the central nervous system (CNS) about the muscle's length.
Contraction-Induced Collapse: When the muscle contracts, it shortens, and the muscle spindle, being in parallel with the extrafusal muscle fibers (alpha motor neurons activity), also collapses. This collapse is a mechanical consequence of the muscle contraction.
Floppiness and Reduced Sensitivity: As the muscle spindle collapses, it becomes floppy and loses its taut structure. This physical change in the spindle's structure results in a reduced ability to detect changes in muscle length. The sensory receptors within the collapsed spindle are less responsive to stretching because they are not under tension.
199
How does alpha-gamma coactivation contribute to muscle spindle function?
Alpha-gamma coactivation ensures that, despite muscle shortening, the intrafusal muscle fibers of the muscle spindle remain stretched, maintaining sensitivity and responsiveness to changes in muscle length.
The primary motor cortex issues motor commands that, through descending pathways, activate both alpha and gamma motor neurons. This leads to extrafusal muscle contraction and shortening (alpha). Simultaneously, gamma motor neurons maintain the sensitivity of the muscle spindle by activating intrafusal muscle fibers. This coordinated mechanism ensures the muscle spindle can detect changes in muscle length, providing crucial feedback to the central nervous system during voluntary movements.
200
What are the properties of stretch reflex (3) ?
1) Resists changes in muscle length (sets muscle tone).
2) Mono- and polysynaptic components.
3) Feedback from muscle spindles.
201
What are the properties of muscle spindles ? (6)
1) Reports muscle length.
2) In parallel with extrafusal muscle fibers (does not contribute to the
force of muscle contraction).
3) Ia primary: Detects changes in muscle length and some static length
(nuclear bag fibers).
4) II secondary: Detects static length (nuclear chain fibers).
5) Intrafusal fibers: Maintain muscle spindle sensitivity.
6) Alpha-gamma coactivation.
202
What stimulus does the Golgi tendon organ respond to?
tension
203
In what way is the Golgi tendon organ different from the muscle spindle in terms of its location in the muscle?
The Golgi tendon organ is located in series with the muscle, in the tendon, whereas the muscle spindle is in parallel with the muscle fibers.
204
How does the Golgi tendon organ contribute to proprioceptive feedback?
During active contraction of extrafusal muscle fibers, the Golgi tendon organ, being in series with the muscle, detects the generated force and provides information about the duration and magnitude of the force, enhancing proprioceptive feedback.
205
Explain the system for detecting force with the Golgi tendon
The system for detecting force operates through the interaction of various components. Inside the Golgi tendon organ, there are robust collagen fibers, interspersed with free nerve endings of the afferents. These nerve endings possess mechanically gated ion channels. When force is exerted on the Golgi tendon organ, the collagen fibers experience stretching and compression, causing them to pinch the free nerve endings. This action activates the mechanically gated ion channels. Consequently, proprioceptive feedback is generated from the Golgi tendon organs, providing information about the force exerted by the muscles during contraction. In essence, the process involves the mechanical interaction between collagen fibers, nerve endings, and ion channels to convey a sensory response to applied force.
206
Explain the golgi tendon organ reflex pathway (inverse stretch)
Activation of the Golgi tendon organ leads to the increased tension in the extensor muscle (felt by Golgi). This will lead to increased afferent activity from Golgi tendon organ via 1b afferents. Some going up the dorsal columns, while others branches into the gray matter of the spinal cord, activating interneurons. This will result in the inhibition of motor neurons innervating the ipsilateral extensor and in the excitation of the motor neuron innervating the ipsilateral flexor.
207
What are the properties of Golgi tendon organ?
1) Reports muscle tension.
2) In series with extrafusal muscle fibers.
3) Ib afferents.
4) Underlies inverse stretch reflex (polysynaptic).
208
What are the two main descending pathways from the motor cortex?
The two main descending pathways from the motor cortex are the corticospinal tract, governing skilled movements, and the extrapyramidal tract originating from the brainstem.
209
What is the primary function of the corticospinal tract in voluntary movements?
skilled movements
210
What role does the extrapyramidal tract play in voluntary movements?
adjustments in trunk and posture during movements
211
How do muscle spindles and Golgi tendon organs contribute to voluntary movements?
Muscle spindles and Golgi tendon organs provide feedback for real-time adjustments in voluntary movements, contributing to the dynamic and adaptive quality of these movements.
212
What is the middle level of motor control responsible of? (2)
1) Executes the individual muscle contractions.
2) Makes corrections based on sensory information.
213
why are voluntary movements considered to have an "involuntary" component?
Voluntary movements are not solely under conscious control; they involve an involuntary component, especially in the middle level, where movements are planned and dissected into distinct muscle contractions.
214
Explain the voluntary control of movements within different areas of the brain?
The frontal areas consciously initiate a movement.
Sensory motor cortex= Pre motor cortex + Primary motor cortex.
Primary motor cortex located on the other side of the central sulcus from the somatosensory cortex.
Once the primary motor cortex receives the planned movement, its neurons activate and send signals down the spinal cord.
215
Describe the somatotopic map orientation of the primary motor cortex when moving from medial to lateral.
Moving from medial to lateral in the primary motor cortex corresponds to the arrangement of the head, arms, and legs.
216
Which regions in the primary motor cortex occupy more surface area of the the somatotopic map.
Certain areas in the primary motor cortex, particularly those associated with intricate and skilled movements, occupy more surface area, with significant representation for the hands and face.
217
What are the 3 thing the somatotopic motor representation reveal?
1) Systematic relationship between select muscle groups and the
body areas they control.
2) Size of body structures in primary motor cortex is proportional
to the number of neurons dedicated to their motor control.
3) Size of body structures in primary motor cortex is proportional
to the degree of skill required to operate that area of the body.
218
What are the areas of the middle level?
Sensorimotor cortex
Basal nuclei
Thalamus
Brainstem
cerebellum
219
Explain the two descending motor pathways.
Corticospinal:
1) Originates in primary motor cortex (precentral gyrus).
2) Compact, discrete fiber tract direct to spinal cord. (direct and indirect)
3) Crossed: Controls contralateral muscles. (crossing in the medulla).
4) Extremities: Predominantly hands and feet.
5) Controls skilled voluntary movements.
Extrapyramidal:
1) Originates from neurons in brainstem.
2) Diffused and indirect: Several descending tracts via the brainstem. (innervate interneurons)
3) Crossed and uncrossed. (ipsilateral and contralateral)
4) Trunk and postural muscles.
5) Controls upright posture, balance, and walking.
220
Define muscle tone.
the resistance of skeletal muscle to stretch
221
How is muscle tone described in a normal subject?
In a normal subject, muscle tone is slight and uniform.
222
What does damage to descending pathways cause?
1) Hypertonia: Abnormally high muscle tone.
2) Spasticity: Overactive motor reflexes.
3) Rigidity: Constant muscle contraction
(decrease inhibition = overactive spinal cord)
223
What does damage to motor neurons cause?
1) Hypotonia: Abnormally low muscle tone.
2) Atrophy: Loss of muscle mass.
3) Decreased or missing reflexes.
(no stretch reflex)
224
What does the basal nuclei do?
collection of cell bodies: Helps to determine the specific sequence of movements needed to accomplish a desired action
225
What are the two basal nuclei movement disorders?
Parkinson disease
Huntington disease
226
Explain Parkinson disease and symptoms:
One of the most common movement disorders.
Reduced dopamine input to the basal nuclei.
1) Akinesia: Reduced movements
2) Bradykinesia: Slow movements
3) Muscular rigidity
4) Resting tremor (contrast with cerebellar deficits)
Treatment includes increasing dopamine concentrations in the brain.
227
Explain Huntington disease and symptoms:
Genetic mutation that causes widespread loss of neurons in the brain.
Shows up later in life.
Neurons in the basal nuclei are preferentially lost.
1) Hyperkinetic disorder: excessive motor movements
2) Choreiform movements: jerky, random involuntary movements of limbs and face
228
What does the cerebellum do?
Movement timing, planning,
and error correction.
Learning new motor skills.
Receives sensory information:
vestibular, visual, auditory,
somatosensory, proprioceptive.
Cerebellum contains almost half of the brain’s neurons.
229
Explain the cerebellar deficits?
1) Asynergia: Smooth movements are subdivided into their separate components.
2) Dysmetria: Unable to target movements correctly “past pointing”.
3) Ataxia: Incoordination of muscles groups (awkward gate).
4) Intention tremor: During voluntary movements.
5) No paralysis or weakness.
