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neuro - block 2 > thalamus + cortex (dr maloney) > Flashcards

thalamus + cortex (dr maloney) Flashcards

1
Q

how are cells organized/layered in lateral geniculate nucleus

A

by cell type + eye:

  1. magnocellular: contra
  2. magnocelular: ipsi
  3. parvocellular: ipsi
  4. parvocellular: contra
  5. parvocellular: ipsi
  6. parvocellular: contra

ex. if we are in the right LGN, layer 1 is input from magnocellular cells in the left eye

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2
Q

info from the nasal side of eyefields DOES/DOES NOT cross in optic chiasm

A

DOES

(fibers from left eye cross to right in optic chiasm and project to right LGN)

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3
Q

info from the temporal hemifeild DOES/DOES NOT cross in optic chiasm

A

does NOT

(fibers from left eye remain on left and project to left LGN)

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4
Q

BLANK cell layers seperate/sandwich between the parvocellular and magnocellular layers

A

KONIOcellular

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5
Q

thalamacortical cells (def)

A

project from thalamus to cortex

generally round and bushy, make up ~80-98% of neuron cell bodies in thalamus

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6
Q

intrinsic interneurons (def)

A

other major neuron type in thalamus (besides thalamacortical neurons)

form sparse dendrites over a large area, dont leave thalamus

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7
Q

what percentage of neuron cell bodies in thalamus do intrinsic interneurons take up

A

~2-20%

(other 80-98% made up of thalamacortical neurons)

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8
Q

the receptive fields in thalamus/lgn are largely THE SAME/NOT THE SAME as those in the retina/rgc

A

THE SAME

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9
Q

inputs to the thalamus/types of synapses occuring within the thalamus

A

drivers and modulators

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10
Q

drivers (thalamus) def.

A

primary excitatory inputs to thalamus

drive response of thalamocortical cells because these synapses are stronger than the others (which are mostly inhibitory)

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11
Q

what percentage of synapses in the thalamus are drivers

A

~5% of synapses

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12
Q

what percentage of synapses in the thalamus are modulators

A

~95% of synapses

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13
Q

modulators (thalamus) types

A

nonspecific and specific modulators

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14
Q

nonspecific modulators (thalamus) def

A

global,

mostly coming from brainstem (acetylcholine, seratonine, norepi)

largly serve function of global arousal (sleep/wake cycles for retic form.)

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15
Q

specific modulators (thalamus) def, where they project from, funciton

A

target localized part(s) of thalamic region

primarily from layer VI of cortex (thalamacortical neurons) and the thalamic reticular nucleus (TRN)

involved in attention + specifically gating information/selective control

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16
Q

firing modes of thalamicortical neurons

A

tonic firing + burst firing

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17
Q

burst firing (def)

A

all or nothing response (a lot of spikes or zero spikes)

burst firing thalamocortical neurons are “detectors,” quite useless unless something very important shows up

18
Q

tonic firing (def)

A

tracks the amount of spikes in the input (not j a bunch of spikes all at once then none)

faithful relaying of info (constant)

19
Q

rythems in thalamus (def + func)

A

thalamus (w/thalamic reticular nucleus) is responsible for brain rythyms

most prominent during sleep where one can see/measure “sleep spindles” – debated whether they have a function

20
Q

the TRN (thalamic reticular nucleus) receives input from BLANK and gates what gets into the BLANK

A

the TRN (thalamic reticular nucleus) receives input from LAYER VI OF CORTEX and gates what gets into the THALAMUS

21
Q

francis crick thought BLANK had a role in conciousness

A

TRN

22
Q

primary nuclei of thalamus

A
  1. lateral geniculate nucleus (LGN)
  2. medial geniculate nucleus (MGN)
  3. VPL/VPM of thalamus
23
Q

the primary nuclei of thalamus receive info from BLANK and send it onto BLANK

A

receive info from OUTSIDE OF CORTEX and sent it onto CORTEX

24
Q

association nuclei of thalamus

A

pulvinar nucleus + mediodorsal nucleus

25
Q

the association nuclei of thalamus receive info from BLANk and sent it onto BLANK

A

receive info from ONE PART OF CORTEX and send it onto ANOTHER PART OF CORTEX

26
Q

motor thalamus (VA/VL) receive info from BLANK and send it onto BLANK

A

receive info from BASAL GANGLIA/CEREBELLUM and send it onto MOTOR CORTEX

27
Q

what is the intralaminar nucleus (func)

A

receives info from reticular formation

part of the reticular activation pathway

projects directly onto cortex

28
Q

name main 3 cell types in cortex

A

pyramidal cells (excitatory)

spiny stelate cells (excitatory)

inhibitory interneurons (inhibitory)

29
Q

pyramidal cells

A

excitatory cells that project to cortical areas or thalamus (75% of cells)

largely define the activity/responses of cortex

30
Q

spiny stelate cells

A

local excitatory cells, involved in computation within an area

31
Q

inhibitory interneurons

A

non-spiny neurons in cortex (wide range of types)

help shape response of pyramidal cells, tend to have broader domains and broader tuning

32
Q

how many layers are in neocortex

A

6

33
Q

tuning (def)

A

the way neurons respond selectively to specific features or stimuli within their receptive field

34
Q

generally speaking primary input goes into layer BLANK of cortex

A

IV/four

35
Q

after entering layer IV of cortex, input goes BLANK

A

either to layers II and III (where it then goes to cortex) OR layers V and VI (where it then goes to thalamus/TRN/other subcortical structures)

36
Q

ocular dominance columns (def)

A

columns of neurons in primary visual cortex that respond preferentially to one eye

these columns are consistant vertically and are one (of many) types of column in visual cortex

37
Q

orientation comes from BLANK cells discovered by BLANK (won nobel prize)

A

SIMPLE cells discovered by HUBEL AND WEISEL

38
Q

simple cells (function)

A

help with orientation.

thought to be generated by combining inputs from lateral geniculate nucleus specifically to make a bar

39
Q

complex cells (function)

A

respond to oriented bars accross multiple locations in space making them “spacially invarient”

adapt quickely - therefore sensitive to motion

40
Q

hypercomplex cells (function)

A

also known as “end stopped cells”

like complex cells EXEPT only respond to bars of short length rather than a moving edge (longer bar/complex cells)

41
Q

true/false: excitatory neurons have SHARPER tuning than inhibitory ones

A

true!

42
Q

cytochrome oxidase blobs (def)

A

specialized regions made up of kiniocellular cells found in layers 2 + 3 of visual cortex (blobs as opposed to columns like parvo and magnocellular cells)

have high concentration of cytochrome oxidase (enzyme) which is involved in mitochondrial respiration + energy production

neuro - block 2 (9 decks)

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