1
Q
What is the focus of neuroscience?
A
How nervous systems of humans and animals are organized, developed, and function to generate behavior
Multiple disciplines are involved in the study of neuroscience.
2
Q
Name the three major neural systems.
A
- Sensory systems
- Motor systems
- Associational systems
Each system has distinct roles in processing information and generating behavior.
3
Q
What does the sensory system do?
A
Reports info about the state of the organism and its environment
It is one of the three major neural systems.
4
Q
What is the role of the motor system?
A
Organizes and generates actions
It acts upon sensory information.
5
Q
What functions does the associational system provide?
A
- Perception
- Attention
- Memory
- Emotions
- Language
- Thinking
It integrates information from sensory and motor systems.
6
Q
What are the two main components of the human nervous system?
A
- Central nervous system (CNS)
- Peripheral nervous system (PNS)
CNS includes the brain and spinal cord; PNS includes sensory neurons and motor divisions.
7
Q
Who discovered neurons and supported the reticular theory?
A
Camillo Golgi
He believed all neurons form a single continuously connected network.
8
Q
What is the neuron doctrine proposed by Ramon y Cajal?
A
Neurons are not physically connected but communicate at specialized contact points called synapses
This theory countered Golgi’s reticular theory.
9
Q
What are the primary cells of the brain?
A
- Neurons
- Glia
Neurons process information, while glia support neuronal functions.
10
Q
What is the function of dendrites?
A
Where synaptic input comes in
The complexity of dendritic arbor depends on the number of inputs.
11
Q
What is an axon?
A
Transports signal from cell body
It is the site of output to other neurons.
12
Q
What is an action potential?
A
Electrical event that carries signals
It is an ‘all or nothing’ event.
13
Q
What are neurotransmitters?
A
Specialized molecules released from presynaptic terminal that bind receptors in postsynaptic density
They cross the synaptic cleft to communicate between neurons.
14
Q
What are the types of glia?
A
- Astrocytes
- Oligodendrocytes
- Schwann cells
- Microglia
- Glial stem cells
Each type has distinct functions in supporting neurons.
15
Q
What is the role of astrocytes?
A
Maintain appropriate chemical environment for neuronal signaling
They are found only in the brain and spinal cord.
16
Q
What do oligodendrocytes do?
A
Lay down myelin around axons
They regulate the speed of transmission of action potentials in the CNS.
17
Q
What is the function of Schwann cells?
A
Provide myelin in the peripheral nervous system
They are crucial for the insulation of peripheral axons.
18
Q
What are neural circuits?
A
Subsets of neurons that process specific types of information
The direction of info flow defines the circuit.
19
Q
What are afferent neurons?
A
Information toward CNS
They carry sensory information to the central nervous system.
20
Q
What are efferent neurons?
A
Information away from CNS
They transmit motor commands to muscles.
21
Q
What is the knee-jerk reflex an example of?
A
A reflex circuit involving sensory and motor neurons
It demonstrates the flow of information in neural circuits.
22
Q
What is electrophysiological recording?
A
Primary technique to study neural circuits
It includes extracellular and intracellular recordings.
23
Q
What is calcium imaging used for?
A
Record transient changes in concentration of calcium ions and associated action potential firing
It helps assess neuronal activity.
24
Q
What does optogenetic technique involve?
A
Activation of neuronal populations through sensitivity to light
It allows for the assessment of physiology of neural circuits.
25
What are the **three sub-systems** of the somatic sensory system?
* Fine touch, vibration, pressure
* Proprioception
* Temperature, pain, and non-discriminative touch
## Footnote
Each sub-system processes different types of sensory information.
26
What is **transduction** in sensory systems?
Converting one signal/stimulus into another
## Footnote
It is a key process in how we perceive stimuli.
27
What are the **five basic senses**?
* Somatic
* Vision
* Audition
* Taste
* Smell
## Footnote
Proprioception is often considered the sixth sense.
28
What is the role of **afferent pathways**?
Conveys sensory information to the brain
## Footnote
They are crucial for processing sensory input.
29
What is the **receptive field**?
Area of skin that is tuned to a stimuli
## Footnote
The size of the receptive field varies across different body parts.
30
What is **two-point discrimination**?
Ability to sense two stimuli as distinct
## Footnote
It varies by body part; fingertips have the smallest distance for discrimination.
31
Which type of nerve endings have the **largest axon diameters**?
Free nerve endings (pain) are smallest
## Footnote
This indicates a relationship between axon diameter and sensory function.
32
Define **receptive field**.
Area of skin that is tuned to a stimuli
## Footnote
Different body parts have different sizes of receptive fields.
33
What determines the **size of receptive fields**?
* Branching of sensory afferents in skin
* Density of afferent innervation
## Footnote
Smaller arborization leads to smaller fields; more afferents lead to smaller receptive fields.
34
What is **two-point discrimination**?
Distinct discrimination needed to sense stimulus as two different stimuli
## Footnote
Varies by body part: fingertips (2mm) vs. forearm (40mm).
35
True or false: **Temporal dynamics** refers to different sensory afferents responding to the same stimulus with the same timing.
FALSE
## Footnote
Different afferents can fire upon initiation, become quiescent, and fire again on termination.
36
What are the **four distinct mechanoreceptors** involved in somatic sensation?
* Merkel cell-neurite complex
* Meissner corpuscle
* Pacinian corpuscle
* Ruffini corpuscle
## Footnote
Each mechanoreceptor has unique properties related to receptive field size and function.
37
What is **haptics**?
Active touching
## Footnote
It involves the sensory feedback received during manipulation of objects.
38
Define **stereognosis**.
Capacity to identify an object by manipulating it with the hand
## Footnote
This skill relies on proprioceptive and tactile feedback.
39
What do **Merkel cell afferents** primarily detect?
Points, edges, and curvature
## Footnote
They are slow adapting and provide the highest spatial resolution.
40
What is the role of **proprioceptors**?
Provide continuous detailed info about position of limbs and body in space
## Footnote
They are crucial for fine-tuned movement.
41
What do **muscle spindles** sense?
* Speed
* Position of muscles
* Change of movement
## Footnote
They are essential for proprioception.
42
What is the function of the **Golgi tendon organ**?
Sense changes in muscle tension
## Footnote
It helps prevent muscle damage during excessive force.
43
What are the **two types of sensory info** that reach the brain?
* Proprioception
* Touch
## Footnote
Both are essential for movement and spatial awareness.
44
What is the **dorsal spinocerebellar tract** responsible for?
Conveying proprioceptive info from the lower body to the cerebellum
## Footnote
It is part of the central pathways for proprioception.
45
What is the **primary somatosensory area** designated as?
S1
## Footnote
It includes areas 3a, 3b, 1, and 2, each with distinct functional properties.
46
What does the **VP lateral nucleus** relay?
Info from the lower and upper body
## Footnote
It is part of the thalamic relay to S1.
47
What is the **function of area 3b** in the somatosensory cortex?
Critical for processing cutaneous stimulation
## Footnote
It serves as an obligatory first step in cortical processing.
48
What is the **retinoid cycle**?
Reset opsin so it can be activated again
## Footnote
It involves converting all-trans retinal back to 11-cis retinal.
49
What are the **three types of cones** in the human eye?
* S cones (blue light)
* M cones (green light)
* L cones (red light)
## Footnote
Each cone type is sensitive to specific wavelengths of light.
50
What is **achromatopsia**?
Complete colorblindness
## Footnote
It is a rare condition affecting color perception.
51
What do **ON-center ganglion cells** respond to?
Light in their receptive field center
## Footnote
They are excited by brightening stimuli.
52
What is the role of **horizontal cells** in the retina?
Provide negative feedback to photoreceptors
## Footnote
They help modulate the response of photoreceptors to light.
53
What is the **maximum response** of a ganglion cell in relation to its receptive field?
Full field is activated
## Footnote
The center field plus some surround is activated.
54
What type of ganglion cells are **inhibited by light** in their receptive field center?
OFF-center ganglion cells
## Footnote
They are excited by light in the receptive field surround.
55
What provides **negative feedback** to photoreceptors when only the center photoreceptor is activated?
Horizontal cells
## Footnote
They activate weakly nearby.
56
What do **amacrine cells** provide to bipolar cells and ganglion cells?
Lateral inhibition
## Footnote
This helps in processing visual information.
57
What is the **luminance** in terms of visual perception?
Physical measurement of light intensity
## Footnote
It is not good at perceiving luminance as it depends on context.
58
What is the difference between **brightness** and luminance?
Brightness is the sensation elicited by light intensity
## Footnote
It relates to our perception rather than a physical measurement.
59
True or false: Some ganglion cells are sensitive to a **specific direction of motion**.
TRUE
## Footnote
They have a preferred direction and null direction.
60
What are the **predominant ganglion cell types**?
* Parasol (Magnocellular): luminance
* Midget (Parvocellular): red/green color opponent
* Bistratified (Koniocellular): blue/yellow color opponent
## Footnote
Each type has specific functions related to visual processing.
61
What is the role of the **lateral geniculate nucleus** (LGN) in the visual system?
Relay neurons project to primary visual cortex
## Footnote
It is crucial for conscious vision.
62
What is the **pupillary light reflex** pathway?
Activated retinal ganglion → pretectum → Edinger-Westphal nucleus → ciliary ganglion
## Footnote
This pathway causes the pupil to constrict.
63
What are the two types of **eye movements** mentioned?
* Saccadic eye movements: quick movements
* Smooth pursuit eye movements: slow movements
## Footnote
Both are essential for tracking visual targets.
64
What happens to visual information from the **right visual field**?
It goes to the left hemisphere
## Footnote
This is due to the crossing of signals at the optic chiasm.
65
What is the **function of area MT** in the dorsal stream?
Involved in detection of motion
## Footnote
It processes motion information from visual input.
66
What is **cataract**?
Clouding of lens
## Footnote
It accounts for half of blindness and is commonly due to aging.
67
What is **age-related macular degeneration** (AMD)?
Affects photoreceptors in macula and fovea
## Footnote
It impacts high-resolution central vision and is a leading cause of vision loss in people over 55.
68
What is the main focus of **vision restoration** therapies?
* Cell therapy
* Gene therapy
* Retinal prosthetic implants
* Optogenetic therapy
## Footnote
These approaches aim to restore sight by addressing retinal damage.
69
What is the **aperture problem** in visual perception?
V1 receptive fields are small, giving misleading information on direction of movement
## Footnote
Area MT resolves this by integrating inputs from different V1 receptive fields.
70
What is the role of **tip-links** in hair cells?
Translate hair bundle movement into receptor potential
## Footnote
They connect tips of adjacent stereocilia and open cation-selective channels.
71
What is the **tonotopy** in the cochlea?
Systematic representation of sound frequency along the cochlea
## Footnote
It allows for the decomposition of acoustical waveforms.
72
What is **prosopagnosia**?
Face blindness
## Footnote
It is thought to be caused by damage to face-selective visual regions.
73
What do **hair cells** respond to in terms of sound?
* Specific sound orientations
* Specific frequency
## Footnote
Hair cells can produce a sinusoidal wave in response to low frequency sinusoidal stimulation.
74
How does the **amplitude** of a signal affect the hair cell response?
* Low amplitude, high frequency = small DC shift
* High amplitude, high frequency = larger DC shift
## Footnote
Amplitude is encoded by the size of the graded potential.
75
What is the **ionic basis** of mechanotransduction in hair cells?
* Apex in scala media (endolymph rich in K+, poor in Na+)
* Basal end in perilymph (poor in K+, poor in Na+)
## Footnote
The endocochlear potential is 80 mV positive.
76
What is the role of the **auditory nerve fibers** in relation to hair cells?
* Release neurotransmitter when depolarized
* Fire in the rising phase of low-frequency sounds
## Footnote
This results in phase-locking, providing temporal information for sound localization.
77
What are the **three divisions** of the cochlear nucleus in the brainstem?
* Anteroventral
* Posteroventral
* Dorsal
## Footnote
Tonotopic organization of the cochlea is maintained in these subdivisions.
78
What is the function of the **medial superior olive (MSO)**?
* Computes interaural time differences (ITD)
* Receives binaural inputs from bilateral anteroventral cochlear nuclei
## Footnote
MSO contains cells sensitive to different ITDs.
79
What do the **lateral superior olive (LSO)** and **medial nucleus of trapezoid body (MNTB)** compute?
* Interaural intensity differences (IID)
## Footnote
LSO neurons receive excitatory inputs from ipsilateral cochlear nucleus and inhibitory inputs from contralateral MNTB.
80
What is the **vestibular system** responsible for?
* Balance
* Gaze stabilization
* Head movement
* Sense of orientation
## Footnote
It processes sensory information underlying motor responses and perception of self-motion.
81
What are the two **otolith organs** in the vestibular system?
* Utricle
* Saccule
## Footnote
They respond to linear accelerations of the head and static head position relative to gravity.
82
What do the **semicircular canals** detect?
* Head rotations
* Angular accelerations
## Footnote
They contain sensory epithelium (crista) found in the ampulla.
83
What is the **vestibulo-ocular reflex (VOR)**?
* Fast, involuntary reflex stabilizing images during head movements
## Footnote
It produces eye movements in the opposite direction to maintain gaze on a fixed point.
84
What happens when **cold water** is injected into one ear canal during clinical evaluation?
* Induces slow eye movement toward the irrigated ear
* Fast movement away from the irrigated ear
## Footnote
This mimics rotational movement of the head.
85
What is the **final common path** in motor control?
* Reflexive and voluntary movement
## Footnote
It represents the last step before muscle activation.
86
What is the role of the **basal ganglia** in movement?
* Motor control
* Movement reinforcement
## Footnote
It processes information from the cortex and sends it back to the cortex.
87
What do **proximal muscles** control?
* Position of the body
* Locomotion
## Footnote
They are located in the medial ventral horn of the spinal cord.
88
What is the **function of local circuit neurons**?
* Control rhythmic movements
* Assist in walking
## Footnote
They are involved in the final steps of motor control before muscle activation.
89
Where do **lower motor neurons** enter motor neuron pools?
Through the dorsal horn, remain in the ventral horn
## Footnote
This is part of the circuitry dedicated to controlling arms and legs.
90
What type of control do **proximal muscles** have?
Ipsilateral control
## Footnote
Proximal muscles are located closer to the spinal cord.
91
What are the two types of local circuit neurons in the spinal cord responsible for?
* Proximal muscles: long-distance local circuit neurons
* Distal muscles: short-distance local circuit neurons
## Footnote
Proximal muscles control body position and locomotion, while distal muscles mediate fine control.
92
What are the two types of **motor neurons** in the ventral horn?
* Y motor neurons
* Alpha motor neurons
## Footnote
Y motor neurons send sensory information, while alpha motor neurons generate force for movement.
93
What is the **innervation ratio** for fine movement?
Lower innervation ratio (1 alpha to 10 fibers)
## Footnote
Muscles controlling our eyes have the lowest innervation ratio.
94
What are the three different types of **motor units**?
* Slow motor units (S)
* Intermediate alpha motor neurons (FR)
* Fast-fatigable motor units (FF)
## Footnote
Each type serves different functions in muscle activation and fatigue resistance.
95
What does the **size principle** state?
Small, slow motor units have lower thresholds for activation than larger units
## Footnote
This principle explains how muscle force is graded based on the size of motor units recruited.
96
What are **muscle spindles** responsible for?
Sensing changes in muscle length
## Footnote
They contain intrafusal fibers and are involved in the stretch reflex.
97
What is the simplest motor reflex?
Stretch reflex
## Footnote
It involves group 1a sensory afferents exciting motor neurons that innervate synergistic muscles.
98
What do **Golgi tendon organs** (GTOs) respond to?
Force
## Footnote
They help maintain a steady level of force during muscle contraction.
99
What are the two phases of **locomotion** controlled by local circuits?
* Stance: extending muscle, limb in contact with ground
* Swing: muscle is flexed, limb off the ground
## Footnote
Rhythmic movements are adjusted based on altered circumstances.
100
What is the role of the **primary motor cortex** (PMC)?
Mediates planning and initiation of movements
## Footnote
It is located in the precentral gyrus and has a low threshold for eliciting movements.
101
What are **Betz cells**?
Largest cell soma in CNS, found in PMC
## Footnote
They are important for fine movement control of distal muscles.
102
What is the **corticospinal tract** responsible for?
Controls distal muscles
## Footnote
It decussates at the caudal medulla and terminates in the lateral ventral horn.
103
What does **intracortical microstimulation** suggest about motor maps?
Movements are organized, not individual muscles
## Footnote
It shows that stimulation can elicit coordinated movements involving multiple muscles.
104
What is the **population vector** in motor control?
Main direction of movement commands encoded in population activity
## Footnote
It reflects the preferred direction of activation for upper motor neurons.
105
What is the **preferred direction** of activation for upper motor neurons in the PMC?
Increased neuronal firing before preferred direction
## Footnote
Neurons have a preferred direction of activation, with increased activity before movements in that direction.
106
What are the **two pathways** from the premotor cortex?
* Premotor cortex → primary motor cortex → spinal cord
* Premotor cortex → directly mediate movement
## Footnote
These pathways indicate both direct and indirect influences on motor behavior.
107
The **medial division** of the premotor cortex is also known as the _______.
supplementary motor area
## Footnote
This division is typically divided into dorsal premotor (dPMC) and ventral (vPMC).
108
True or false: The **lateral premotor cortex** is important in ‘closed loop’ tasks.
TRUE
## Footnote
It has input from visual stimuli and fires at the appearance of cues.
109
What do **mirror neurons** in the ventrolateral premotor cortex respond to?
* Observed movement
* Self-initiated movement
## Footnote
They suggest that the premotor cortex plays a role in encoding observed actions of others.
110
What happens when there are **lesions** in the lateral premotor cortex?
Impairment of ‘closed loop tasks’
## Footnote
This affects the ability to perform visual cue conditioned tasks.
111
What is the role of the **reticular formation** in motor control?
Mediates feedforward adjustments to stabilize posture during movement
## Footnote
It receives input from various brain regions to initiate adjustments.
112
What are the **three main parts** of the cerebellum?
* Cerebrocerebellum
* Spinocerebellum
* Vestibulocerebellum
## Footnote
Each part has distinct functions related to movement coordination and balance.
113
What is the primary function of the **cerebellum**?
Predicting and correcting motor error based learning
## Footnote
It modifies movement by regulating upper motoneurons.
114
What are the **major outputs** from the cerebellum?
* Dentate nucleus
* Interposed nucleus
* Fastigial nucleus
* Vestibular nuclei
## Footnote
These nuclei are involved in different aspects of motor control.
115
What is **ataxia**?
Difficulty producing smooth, well-coordinated movement
## Footnote
It is often associated with cerebellar damage.
116
What are the **two inputs** to the cerebellum?
* Mossy fibers
* Climbing fibers
## Footnote
Mossy fibers come from the cortex and brainstem, while climbing fibers come from the inferior olive.
117
What is the role of **dopamine** in the basal ganglia?
Modulates effects of cortical inputs
## Footnote
Dopamine from the substantia nigra pars compacta is crucial for movement initiation.
118
What are the **three cardinal signs** of Parkinson’s disease?
* Tremor at rest
* Rigidity
* Bradykinesia
## Footnote
These symptoms are characteristic of the disease and affect motor function.
119
What is the **direct pathway** in the basal ganglia responsible for?
Facilitating movement
## Footnote
It releases upper motoneurons from tonic inhibition.
120
What is the **indirect pathway** in the basal ganglia responsible for?
Inhibiting movement
## Footnote
It increases tonic levels of inhibition to suppress unwanted movements.
121
What is the effect of **Huntington’s disease** on the indirect pathway?
Weakens tonic inhibition, leading to involuntary movement
## Footnote
This is due to degeneration of neurons in the caudate and putamen.
122
What is the **function** of the vestibulocerebellum?
Maintain posture and balance
## Footnote
It receives input from vestibular nuclei in the brainstem.
123
What is the **role** of the superior cerebellar peduncle?
Almost entirely efferent pathway
## Footnote
It projects to upper motor neurons in primary motor and premotor cortices.
124
What is **dysmetria**?
Over/under reaching target
## Footnote
It is a common sign of cerebellar dysfunction.
NSCI 201
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