CNS Facts Flashcards
1
Q
Where does the Lower Motor Neuron go?
A
Out of the spinal cord (immediately)
2
Q
Effect of lesion in frontal association areas
A
Personality change, difficulty planning & interacting (ex: Phineas Gage)
3
Q
Where does the primary axon for pain/temperature go?
A
Into spinal cord posterior horn & up 1-2 vertebrae
3
Q
Where does the 2nd order neuron for pain/temperature synapse?
A
In the thalamus
3
Q
Similarities between pathways for pain/temperature & discriminative touch
A
-1° neuron enters spinal cord posterior horn -ascends (some distance) ipsilaterally -synapses to 2nd order neuron -2nd order neuron crosses midline -ascends contralaterally to thalamus -synapses to 3rd order neuron -projects to primary (somato)sensory cortex
3
Q
Effect of lesion in primary motor cortex
A
Paralysis (opposite side of body)
4
Q
Function of CNS
A
saliency filter before processing for higher cognitive function
5
Q
Name 4 important components of basal ganglia & pathway(s) they’re involved in
A
- Caudate (direct) - Putamen (direct) - Subthalamic nucleus (indirect) - GP(i) (direct AND indirect)
6
Q
Dopamine mechanism
A
Released by reticular formation Increase arousal & rewarding behaviours Increase motivation & rewards
7
Q
Location in spinal cord of nerves controlling proximal (core) muscles
A
medial side of anterior horn
7
Q
Spinocerebellar loop (describe)
A
- proprioceptive info up spinocerebellar tracts - info to all structures involved with movement INCLUDES: - thalamus -> motor cortex -> spinal cord -> limb movement - spinal cord (direct) -> trunk movement
7
Q
Mechanism of reticular formation action
A
Receive sensory stimuli, pass on to thalamus & hypothalamus, use different neurotransmitters for different responses (Part of ARAS - ascending reticular activating system)
8
Q
Effect of lesion affecting serotonin production
A
Insomnia, anxiety, aggression
10
Q
Location of primary visual cortex
A
very back of occipital lobe
10
Q
Pigment epithelium function & location
A
Beneath rods & cones; black to absorb excess light & prevent interference
11
Q
Location of primary sensory cortex
A
directly posterior to central sulcus
11
Q
Proprioception: conscious or non-conscious?
A
may be either
12
Q
Spinocerebellar loop purpose
A
QUALITY CONTROL of movement (feedback from limbs used to adjust signal to core & trunk)
13
Q
Enteroception: conscious or non-conscious
A
usually non-conscious
14
Q
Which part of the brain does visual recognition?
A
Ventral stream
14
Q
Cerebrocerebellar loop purpose
A
FINE MOTOR CONTROL
15
Q
Basal Ganglia function
A
Broadly influence cortex (via thalamus excitation/inhibition, modifying ongoing AP firing) to modulate voluntary movement Integrate signals
15
Q
Effect of lesion in Broca’s area
A
Broca’s aphasia: non-fluent speech & poor syntax/grammar (comprehension intact)
16
Q
What is in the inner segment of a rod/cone cell?
A
Cell body with lots of mitochondria
16
Function: indirect pathway of basal ganglia
Prevent extraneous movement (decrease motor output)
17
of parallel circuits in Basal Ganglia & names
3: - motor - associative - limbic
17
Role of prefrontal cortex in consciousness
Consider future, behavioural appropriateness, concentration Has executive control of consciousness
17
Fact: unlike the cerebellum, the cortex is wired differently for different functions
(Fact)
17
Effect of lesion in parietal association areas (right side)
Left-side spatial neglect: don't process objects in left half of visual field
18
General basal ganglia pathway
Cortex Basal Ganglia (by one of the circuits) Thalamus Cortex Behaviour
18
Role of temporal association areas
RECOGNITION of stimuli & patterns (incl. speech, in Wernicke's area)
19
Function: cerebrocerebellum (neocerebellum)
complex movement coordination, extremity & eye movement, speech
19
Location of thalamic reticular nucleus
outer edge of thalamus
19
Norepinephrine mechanism
Released by reticular formation Thalamus: increase arousal, wakefulness, attention Increase focus
20
Where does the primary axon for discriminative touch go?
Into spinal cord posterior horn & ascends IPSILATERALLY to the medulla
22
Where in the brain do the fovea project to?
BOTH left & right sides
22
Vestibulocerebellar loop (describe)
- balance info from vestibular apparatus - to vestibular nuclei (in brainstem) - to spinal cord for motion, AND - to cerebellum for feedback through reticular formation to spinal cord, back to vestibular nuclei
23
Where does the 2nd order neuron for discriminative touch go?
Crosses midline, ascends rest of brain stem antero- (contra-)laterally to thalamus
24
Sight transduction mechanism for in-light (8 steps)
- Photon excites rhodopsin/iodopsin - G-protein-mediated pathway - CLOSE Na+ channels - HYPERPOLARIZE - Decrease Glutamate release onto bipolar cells - Stimulate ON bipolar cells/hyperpolarize OFF bipolar cells - Stimulate ON/inhibit OFF ganglion cells - ON ganglion cell fires (more) APs, OFF does opposite
26
Location of primary auditory cortex
directly below central sulcus
27
Location of Wernicke's area
At intersection of parietal and temporal lobes
28
Light-sensitive compound in rod cells
rhodopsin
28
Location: spinocerebellum (paleocerebellum)
vermis & anterior lobe
28
Body parts' spatial representation in the primary sensory cortex is ...
proportional to functionality (same as 1° motor cortex)
29
Rod cell location in retina
Primarily in periphery
30
Differences between pathways for pain/temperature & discriminative touch
Pain/temperature: 1° neuron synapses after travelling up 1-2 vertebrae (signal goes most of the way CONTRAlaterally) Discriminative touch: 1° neuron doesn't synapse until it reaches the medulla (signal goes most of the way IPSIlaterally)
31
Location: Primary sensory cortex
Immediately posterior to central sulcus
32
Function: spinocerebellum (paleocerebellum)
synergistic extremity movement
32
Brain structure primarily involved with state of consciousness
Thalamus
32
Role of frontal association areas
- SOCIAL interactions & "humanity" (e.g. innate morality, planning, etc.) - interact with all other parts of brain - uses all hormones involved with consciousness
33
(Fact) Brain structures involved with consciousness are involved in reciprocal communication
(Fact)
33
Function: Broca's area
(motor) production of language (use of symbols for concepts)
35
Cornea function
Refraction
36
Name the three most important primary cortices
motor, sensory, visual (also have olfactory, gustatory, auditory)
37
Histamine mechanism
Released by reticular formation Increase wakefulness Increase level of consciousness
39
Cone cell location in retina
Primarily in/around fovea
40
Ganglion cell function & location
Synthesize signal from layer below (bipolar cells) & pass on to optic nerve
41
Bipolar cell function & location
Synthesize signal from layer below & pass on; between rods/cones & ganglion cells
43
Where does the 3rd order neuron for discriminative touch go?
To the primary (somato)sensory cortex
44
Optic nerve function
Location of nerve & artery entry into eyeball; creates blind spot (no rods/cones)
44
Brain structure primarily involved with content of consciousness
Cerebral cortex (esp: PREFRONTAL cortex, parietal cortex)
45
Effect of lesion in motor association cortex
apraxia: clumsiness (bad input to basal ganglia results in bad output to 1° motor cortex)
47
Where does the primary axon for discriminative touch synapse?
In the medulla
48
Role of parietal association areas
- ATTENTION & awareness, directing focus to most salient somatic/auditory/visual input - may be directed by/direct pre-frontal cortex - right side processes spatial awareness, left side processes temporal awareness
49
Where do optic nerves synapse?
Thalamus LGN (lateral geniculate nucleus)
49
Reason for chronic inhibition of thalamus by basal ganglia
Prevents unnecessary movement, resulting in efficient, targeted motion
50
Effect of lesion affecting dopamine production
Indecision, inattention
51
Cone cell location
On top of pigment epithelium
52
Cerebrocerebellar loop (describe)
1. cortex -\> pons -\> cerebellum -\> (feedback) cortex via thalamus (& red nucleus, sometimes) 2. cortex -\> UMN (cross midline)-\> LMN for movement
53
Function of Motor circuit in basal ganglia
Promote measured, coordinated body & eye movement
55
Horizontal cell function & location
Horizontal signal integrator (temporal & spatial), help get next layer of cells to threshold; link rods/cones & bipolar cells
55
Areas where language is processed:
Broca's, Wernicke's (& Arcuate fasciculus)
56
Discuss the mechanism for head and neck movement to maintain visual focus.
- Sight maps to superior colliculus (past lateral geniculate nucleus) - Tectospinal tract originates in & crosses midline in brainstem - Nerves descend contralaterally to move head & neck
57
Effect of lesion in temporal association areas
Agnosia: inability to recognize
58
Function: Subthalamic nucleus
Basal ganglia indirect pathway: when excited, stimulate GP(i)
59
Location of primary motor cortex
directly anterior to central sulcus
59
Role of thalamus in consciousness
Modulates responsiveness by adjusting what does/doesn't reach cortex: prioritizes, discriminates & relays
60
Location: cerebrocerebellum (neocerebellum)
posterior lobe
61
Rod cell location
On top of pigment epithelium
62
Role of thalamic reticular nucleus (input, output & function)
Input: ARAS Output: to rest of thalamus, cortex, ARAS Function: coordinate 40Hz signal to cortex for consciousness
64
Cerebellum lobe size increases with...
function & complexity
65
Body parts' spatial representation in the primary motor cortex is...
proportional to functionality (same as 1° sensory cortex)
66
Lens function
Change shape to aid cornea with refraction, invert image
66
Location: primary motor cortex
immediately anterior to central sulcus
67
Brain structure primarily involved with modulating level of consciousness
Brainstem
68
What is in the outer segment of a rod/cone cell?
Rod/Cone portion; contain disks of light-sensitive compounds
69
Function: direct pathway of basal ganglia
Promote targeted, efficient movement (increase motor output)
71
Mechanism: indirect pathway of basal ganglia
- Subthalamic nucleus (basal ganglia component) stimulates GP(i) (basal ganglia component) - Increase thalamic inhibition - Decrease cortical excitation - Decrease motor output
72
Exteroception: where are receptors?
many in skin
72
Location of Broca's area
in frontal lobe
73
Discuss the mechanism for balance compensation.
- Vestibulospinal tract descends ipsilaterally - Innervates core on same side - Innervates flexors/extensors of limbs on opposite side (crosses midline at level of synapse)
74
Role of cortex in consciousness
Ascribe meaning & significance (what to do)
76
Rod cell function
Detect motion, low acuity; function in very low-light settings (e.g. dusk/night) because very sensitive
77
Which part of the brain does spatial vision?
Dorsal stream
79
Limbic circuit pathway (basal ganglia)
Emotional processing areas Basal Ganglia Thalamus Cortex --\> Motion for emotion
81
Function of thalamus
gatekeeper to consciousness
83
Targets of proprioceptive information
- cortex (conscious, travels w/discriminative touch) - cerebellum (unconscious corrections, travels up spinocerebellar tract WITHOUT EVER CROSSING THE MIDLINE - only ipsilateral)
85
Where does the 2nd order neuron for discriminative touch synapse?
In the thalamus
86
Effect of lesion in primary sensory cortex
poor localization of stimuli (not total loss of function as in paralysis)
87
2 components of pain/temperature signal
Localization (1° sensory cortex) "Ouch" (Limbic system, association cortices)
88
Acetylcholine mechanism (w.r.t. consciousness)
Released by reticular formation Activates thalamus, increasing arousal
89
Location: vestibulocerebellum (archicerebellum)
flocculonodular lobe & vermis
90
How does cross-body visual control work? (what projects where?)
Left hemisphere: right half of visual field, left-side fibers from each optic nerve Right hemisphere: left half of visual field, right-side fibers from each optic nerve
92
Where do optic fibers cross?
Optic chiasm
95
Location of anterior lobe of cerebellum
front-top
96
Reticular formation function
Use different neurotransmitters to influence level of consciousness and cerebral output to spinal cord
97
Where does the upper motor neuron go?
- Descends ipsilaterally through cortex, midbrain, pons, medulla - Crosses midline in caudal medulla if part of lateral corticospinal tract - Travels down anterior horn of lateral column of spinal cord
99
of functional regions in cerebellum, and names
3 (in order of development): - vestibulocerebellum (archicerebellum) - spinocerebellum (paleocerebellum) - cerebrocerebellum (neocerebellum)
101
Light-sensitive compound in cone cells
iodopsin (3 kinds: R, G, B)
102
Motor circuit pathway (basal ganglia)
Motor/Sensory cortices Basal ganglia Thalamus 1° motor cortex --\> Muscle Movement
104
Where is motor control located in the brain?
1° motor cortex (entire body mapped to here)
105
Location in spinal cord of nerves controlling distal (limb) muscles
lateral side of anterior horn
106
Effect of lesion in arcuate fasciculus
Conduction aphasia: inability to repeat back words (language comprehension & production individually intact)
107
Where does the 3rd order neuron for pain/temperature go?
To the primary (somato)sensory cortex
107
Location of flocculonodular lobe of cerebellum
front middle: 2 flocculi, 1 on either side, and 1 nodule in center, below peduncles
108
Serotonin mechanism
Released by reticular formation Promotes quiet, wakefull state Feel settled, content, well
109
Location: primary visual cortex
Very back of occipital lobe
110
Amacrine cell function & location
Horizontal signal integrator (temporal & spatial), help get next layer of cells to threshold; link bipolar cells & ganglion cells
111
Function: direct & indirect pathways of basal ganglia, in concert
Streamline movement by balancing each other out
113
Where does the upper motor neuron synapse, and to what?
In the anterior horn of the spinal cord, to the Lower Motor Neuron (LMN)?
115
Discuss the mechanism for changing muscle tone.
- Reticular formation (in brain stem) integrates signals to determine necessary muscle tone - Controls other regions of brain stem - Lateral & medial vestibulospinal tract, & reticulospinal tract descend ipsilaterally - Cross midline at level of synapse
116
Function of associative circuit in basal ganglia
control cognition, as relates to motion - learn what does and doesn't lead to goal (role decreases as learning progresses)
118
Location of association cortices
all of brain except for primary cortical areas
119
Function of limbic circuit in basal ganglia
For movement: EMOTION (facial expression, posture, etc.) & MOTIVATION (decision whether, where to move)
120
What is the first neuron in the transmission pathway for the motor system?
Upper Motor Neuron (UMN)
121
Effect of lesion affecting norephinephrine production
Low levels of arousal
122
Effect of lesion in Wernicke's area
Wernicke's aphasia: non-sensical speech, made-up words, difficulty in comprehension (fluency, syntax, grammar, word structure intact)
124
Function: vestibulocerebellum (archicerebellum)
trunk control
126
Function: Caudate & Putamen
Basal ganglia direct pathway: when excited, inhibit GP(i)
128
of lobes in cerebellum, and names
3: - anterior - posterior - flocculonodular
130
Cerebellum function (general)
Modulate/adjust firing of Upper Motor Neurons based on internal & external factors
131
Location of posterior lobe of cerebellum
middle/back-top, front-bottom
132
Function of basal ganglia
control movement by controlling cortical output
133
Mechanism: direct pathway of basal ganglia
- Cortex excites caudate & putamen (basal ganglia components) - inhibit GP(i) (basal ganglia component) - decrease thalamic inhibition - increase cortical excitation - increase motor output
134
Thalamus is under _______ \_\_\_\_\_\_\_ by the basal ganglia
chronic inhibition (release-inhibition model: incr/decr inhibition to modulate movement)
135
Function of limbic system
Emotion & saliency filtering
136
spinal tracts most be coordinated so that core movement compensates for limb movement on the opposite side of the body (fact)
(fact)
137
Motor system function
Control limb movement, posture, core, balance, etc.
138
Where do enteroceptive signals go?
cerebellum
139
Function: Wernicke's area
(sensory) language comprehension
140
Where does the 2nd order neuron for pain/temperature go?
Crosses midline, ascends in antero- (contra-)lateral system to brain stem (modulation), to thalamus
142
Effect of lesion affecting histamine production
Drawsiness
143
Associative Circuit pathway (basal ganglia)
Frontal/temporal lobe Basal Ganglia (Spinal cord, if necessary) Thalamus Cortex (FEEDBACK) --\> Learning
144
Cone cell function
Detect colours, provide high visual acuity; require large amounts of light
145
Function: GP(i)
Basal ganglia pathways: when excited (indirect), increase thalamus inhibition; when inhibited (direct), decrease thalamus inhibition
146
Organization of primary sensory cortex
Strips parallel to central sulcus are linked to different types of receptor (e.g. muscle, skin, joints; rapidly-, slowly-adapting)
147
Where does the primary axon for pain/temperature synapse?
1-2 vertebrae above where it enters the spinal cord
148
Vestibulocerebellar loop purpose
BALANCE (stabilize trunk, stabilize image on fovea)
149
Effect of lesion in sensory association cortex
Tactile agnosia - can't make sense of stimuli Astereognosis - can't identify objects in hand
150
Effect of lesions in basal ganglia
Inhibit desired motor output (affecting direct pathway) or prevent suppression of superfluous movement (affecting indirect pathway)
