ANAT321 > Thalamus > Flashcards

Thalamus Flashcards

(59 cards)

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1
Q

How does sensory info reach cerebral cortex

A

sensory info passes through thalamus to reach cortex
Also dorsal column and anterolateral pathways meet up in thalamus

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2
Q

what is thalamus

A

Gateway to cortex
Determines info that gets there, regulates into flow
Typically all information to cortex goes through thalamus, some exceptions tho

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3
Q

Describe how brain can be sectioned

A

3 planes =
Coronal
Horizontal = looking down on sections of Brain
Sagittal = usually mid sagittal, = down midline

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4
Q

describe what brain mostly comprised of = what we call the cortex

A

Cortex = thin sheet around surface of brain
Inside = bunch of white matter

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5
Q

do the 2 thalamus interact

A

Nooo
Sometimes they touch each other - depends on anat of persons brain

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6
Q

how is thalamus organized

A

As numerous discrete nuclei
Collection of nuclei

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7
Q

describe organization of thalamus

A

Nuclei arranged into = specific relay, association and intralaminar

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8
Q

how are thalamic nuclei named

A

Usually named based on area - location
Except for lgn, not named by location

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9
Q

describe specific relay nuclei generally

A

Convey specific sensory modalities to primary sensory cortex
Involved in sensory functions
Most commonly thought of as thalamus, connects sensory systems to cortex

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10
Q

describe ex of specific relay nuclei named adescribe= vpl and vpm

A

Ventral posterior lateral = relay info from body
Ventral posterior medial = relay into from head
= relay somatic sensory input (fine touch, vibe, proprio,temp, pain) to primary somatic sensory cortex Involved
= excitatory synapse with neurons in nucleus —> axons extend to specific region of cortex = primary somatic sensory cortex

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11
Q

describe lgn

A

Lateral geniculate nucleus relays visual info to primary visual cortex
Retina - optic nerve —> lgn synapse —> primary visual cortex

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12
Q

describe medial geniculate nucleus

A

Medial geniculate nucleus =relays auditory info to primary auditory cortex
Vestibulocochlear —> brainstem —> medial geniculate nucleus —> cortex

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13
Q

describe specific relay nuclei related to subcortical structures = what do they do

A

Ventral anterior and ventral lateral nuclei = 2 nuclei that receive inputs from cerebellum and basal ganlia and relay to cortex and cortex send info back down

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14
Q

describe specific relay nuclei related to subcortical structures = where do they go

A

Connect cerebellum (coordination) and basal ganglia (select and scale movements) with motor cortex (controls movement)

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15
Q

what are subcortical structures

A

Structures below level of cortex

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16
Q

inputs and cortical outputs = ventral anterior/ventral lateral nuclei

A

Basal ganglia and cerebellum —> motor areas of cortex

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17
Q

inputs and cortical outputs = vpl

A

Medial lemniscus, spinothalamic tract, somatic sensation from body —> primary somatic sensory cortex (post central gyrus)

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18
Q

inputs and cortical outputs = vpm

A

Medial lemniscus, spinothalamic tract (trigeminal nerve), somatic sensation from face —> Primary somatic sensory cortex (post central gyrus)

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19
Q

inputs and cortical outputs = medial geniculate

A

Brachum of inferior colliculus (hearing) —> primary auditory cortex (superior temporal gyrus)

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20
Q

inputs and cortical outputs = lateral geniculate

A

Optic tract (vision) —> Primary visual cortex (occipital lobe)

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21
Q

what do other parts of thalamus do

A

Doing diff things

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22
Q

describe association nuclei = what are they

A

Interconnected with regions of association cortex
Larger in primates and humans= associated with higher brain functions and higher order compelx processes
Gets inputs from cortex

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23
Q

describe association nuclei = describe function

A

How cortex can communicate with itself = either by direct connections between areas of cortex or
Indirectly via thalamus
= why = don’t know, maybe to coordinate actions of Cortex

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24
Q

describe association nuclei = name them

Study These Flashcards
A

Medial dorsal nucleus
Pulvinar nucleus

25
describe association nuclei = medial dorsal nucleus
Connected to prefrontal cortex = responsible for executive functions Interconnect regions in frontal lobe = involved in actions, making, doing, planning Input form cortex —> medial dorsal nucleus —> axons that go back to cortex
26
describe association nuclei = pulvinar nucleus
Projects to parietal temporal association cortex, which integrates sensory info and mediates language Connects back parts, sensory processing in humans - vision, higher order visual processes and stuff
27
inputs and cortical outputs = medial dorsal
Prefrontal cortex, olfactory and limbic structures (cortical, subcortical regions, emotional processing, emotional states,connect emotion to physiological state) —> prefrontal cortex
28
inputs and cortical outputs = Pulvinar
Parietal, occipital and temporal lobes —> parietal, occipital and temporal lobes, superior colliculus
29
what are intralaminar nuclei
Project diffusely to many regions of cortex and subcortical structures like basal ganglia (v connected with it) Likely to be part of ascending arousal system = dorsal pathway
30
fescribe internal medullary lamina
fiber tract,axons going through thalamus Embedded in strips of Lamina = nuclei
31
describe feed forward = gen
Up sensory pathway = as go to higher levels of processing
32
describe feed back = gen
Go back to thalamus= regulate info going through tyhalamus
33
describe what thalamic nuclei receive
Receive reciprocal feedback from cortical regions to which they protect
34
describe ex of feedback in thalamus
axons From visual cortex to lgn outnumber lgn to cortex projections 10 fold = look back down on lgn and can determine infor flow through it = way more feedback than feedforward Feedback v imrpoatnt
35
define feedforward
Projections go up the sensory pathway
36
define feedback
Projects go back down sensory pathway
37
Are the association nuclei = feedback
Noooo Drivers form cortex = drive aps in medial dorsal nucleus
38
describe feedforward = specifically driver
Retina = excitations release glutamate n lgn neurons = driver inputs Feedforward projections driving aps in lgn
39
describe feedback = modulator inputs
From. Cortex to lgn Activating G protein coupled and metabotropic = modulating activity/physiology of lgn and can decide info flow like can depolarize so easier info flow etc
40
describr driver vs modulator inputs to thalamus
Driver= optic tract Modulator = feedback from cortex, neuromodulators neurons project to thalamus and Thalaic reticualr nucleus (gaba) = thin shell neurons around thalamus - all modulate its activity
41
describe thalamus = attention
Gatekeeper, regulating info flow to cortex Hard to select what to pay attention to, if do = everything else drops into background Have to select small part of sensory space to four on Thalamus = first level of sensory attention, feedback from cortex and modulation form brainstem = helps filter info, select important info
42
describr how thalamic relaying neurons exist = 2 modes
Transmission and bursting modes
43
when are relay neurons in transmission mode
Wakefulness = fire single aps that faithfully relay sensory inputs Like if sensory input increase firing rates then thalamic neurons increase firing rates
44
describe transmission mode
Accurately relay info to sensory cortex When awake and alert
45
when are the relay neurons in bursting mode
Thalamic neurons fire bursts of 3-8 aps separated by quiet periods lasting 100s of milliseconds
46
Describe bursting mode
Slow depolarization and oscillations for long time When drift into sleep = Recall eeg of cortical neurons = this is kinda why = bc neurons in thalamus start bursting when sleep
47
what determines if thalamic neuron in transmission or bursting
resting memebrane potential
48
Describe membrane potential when bursting
if membrane potential hyperpolarized = bursting mode If more neg than -65mV = bursting mode
49
Describe membrane potential when transmission mode
If resting membrane= depolarized More positive than -65mV = in transmission mode
50
what shifts neurons into burst mode?? Describe process
Switch between transmission and bursting = bc neuro modulators neuromodulators = like ach, norepi, ha = released during wakefulness = depolarize thalamic neurons around thalamus shift from burst —> tonic firing mode = goes to transmission mode when awake
51
what happens when sleep = what mode are thalamic neurons in
Neurons fire less = less norepi = swift from transmission —> burst
52
Do feedback and feed forward pathways have same amount of neurons
axons from cortex to thalamus outnumber projections form thalamus to cortex = Helps filter/hone in more than get feed forward
53
Why burst when sleep
way of cutting off info = blocks info to cortex fr sleep Individual neurons when awake = switch to burst, could be that burst helps swift attention, lots of nt release = selectively activate neuron
54
what regulates info flow in thalamus
when switch from transmission to burst
55
Summarize thalamus = driver inputs/bursting mode
driver inputs from cortex for association. Nuclei Thalamus = as a filter - neurons can go into bursting mode = blocks sensory information Or Burst = wake up call=shift attention, high frequency action potentials - lots of glutamate (Do not understand which)
56
How does info travel to and from cerebral cortex
Through massive fiber tract = internal capsule
57
describe internal capsule
large fiber tract Neurons from thalamus get to cortex Narrows = axons form thin sheet = squeeze through narrow space then when get to cortex = fans out to innervate whole cortex = branches out Also axons from cortex to spinal cord through here Almost all of input and output of cortex passes through here
58
what happens if stroke in internal capsule
catastrophic
59
describe horizontal view of human brain
internal capsule anterior limb Internal capsule posterior limb
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