week 5

Question 1

Locus ceruleus has what NT? what does it do? where is it found?

Answer 1

Uses NE, sends axons to many locations, especially the cerebral cortex
Found in Mesencephalic Reticular Formation

Question 2

Nucleus of Raphe has what NT? what does it do? where is it found?

Answer 2

Uses serotonin which is associated with sleep, balancing neuromodulation of the cortex.
Found in Mesencephalic Reticular Formation

Question 3

where is substantia nigra found? what does it and what NT does it use?

Answer 3

dopaminergic neurotransmitter release to the prefrontal lobe and areas under the cortex

• excitatory control of attn/reinforcement
• *Found in subthalamus

Question 4

what are the purposes/function of mesenchephalic reticular formation?

Answer 4

– Midbrain arousal system, controls activation levels of cerebral cortex – cut out this part of the brain = intense coma, cerebral cortex would look dead.
– Amount of activity through this relay system influences how much info/gain gets thru to higher cortical areas

Question 5

what is the purpose of the lamina in the thalamus?

Answer 5

3-5 neurons thick with axons. Provides boost to the gain. Not purely arousal but an attention system (ie turn of auditory to pay attention to visual)

Question 6

ventral thalamus transmits what kind of info?

Answer 6

Transmits info from muscles/skin/temperature sense of the body

Question 7

what are the 2 bumps of the pulvinar thalamus?

Answer 7

LGN and MGN

• pulvinar thalamus involved in complex vision, language, grows enormously in higher species
• no direct sensory input, just relay between primary and secondary sensory cortical areas

Question 8

In lower animals, LGN provides only what kind of information?

Answer 8

At first, the LGN provides only coarse spatial information and color, which is all that is needed for basic survival

Question 9

what are 2 of the changes that occur going from lower animals to higher animals for the eyes/brain?

Answer 9

1) eyes move forward in newer predatory species, newly evolved optic nerve fibers divide at the chiasm so that the nasal retina crosses and the temporal retina remains ipsilateral = maintain half and half of the visual field to each side.
2) growing forebrain areas and the midbrain areas have more and more interaction. (Vs frogs: tectum and forebrain had different roles without cross talk)

Question 10

T/F: In higher mammals, the sup colliculus receives not just visual inut but also signals from other senses?

Answer 10

TRUE

Visual, touch AND auditory senses all relay info to the superior colliculus

Question 11

Thalamus carries what information to where?

Answer 11

Thalamus is the area that carries sensory information to cerebral cortex. It contains relay nuclei to cerebral cortex.

Question 12

what is it unique about OKN in chits under 3 months?

Answer 12

Only get nasalward tracking of OKN monocularly
(Then, at 3-4mo of age, a second innervation via LGN>striate cortex>NOT develops to innervate ipsi side, whereas previously only had path to contra NOT via konio fibers, which is why you only got nasalward)

Question 13

which layers in LGN respond to contra eye?

Answer 13

layers 1 4 6

Question 14

which layers in LGN respond to ipsi eye?

Answer 14

2 3 5

Question 15

which layers in LGN dominated by OFF center cells?

Answer 15

3 and 4

Question 16

which layers in LGN dominated by ON center cells?

Answer 16

5 and 6

Question 17

Receptive fields for LGN relay cells are like those of the retinal ganglion cells EXCEPT?

Answer 17

Receptive fields are like those of the retinal ganglion cells but the SURROUNDS are slightly stronger in the parvo & magno cells – color opponancy is a little more perfect
**due to lat inhib and neg feedback from interneurons in LGN

Question 18

Eye related layers can also be shown by injecting a radio active dye into one eye and waiting ____ for it to be transported into the LGN

Answer 18

one week

Question 19

The neurons between the 6 classic layers of LGN respond to what cells?

Answer 19

konio

Question 20

from where does the LGN get the majority of its synapses?

Answer 20

striate cortex (not the retina actually!)=layer 6 of LGN

Question 21

what type of feedback does striate cortex provide?

Answer 21

1) Visual feedback gain control
-can reduce the gain
2) Saccadic suppression
-Magno cell system – excitatory input
•During saccade it briefly turns down the response coming through LGN (“saccadic blink” of darkness so you don’t see world spinning around everytime you move your eyes)
3) Binocular rivalry
•No direct cross-talk between layers of LGN
•The cells in layer 6 of striate cortex are largely binocular.
4) Strabismic suppression
•One eye providing stronger input, can suppress other eye
5) Filling in the blind spot

Question 22

How much of the cortex is devoted to central 10 deg of VF?

Answer 22

A little more than half of this cortex is responsible for the central 10o

Question 23

what is in layer one of cortex?

Answer 23

no neurons, only fibers primarily dendrites (not much is known about it)

Question 24

function of layers 2 and 3 of cortex?

Answer 24

provide information to other areas

Question 25

layer 4 cortex function?

Answer 25

for information from the thalamus and sensory information. ‘

Question 26

Describe layers 5 and 6 of cortex?

Answer 26

has huge pyramidal cells. A big cell body is needed to support a really long axon. No sensory outputs are here – it is the motor cortex. The motor cortex looks different because of this.

Question 27

T/F: Stereo and vernier acuity associated with cortical magnification factor.

Answer 27

true

Question 28

Name several RGC targets in brain:

Answer 28

1) LGN
2) Superior colliculus
3) Pretectum
4) Mesencephalic reticular formation
5) Intralaminar nuclei of the LGN
6) Suprachiasmal nucleus in the hypothalamus
7) Pulvinar nucleus of the thalamus
SLPIMPS

Question 29

layer 1 of LGN gets input from:

Answer 29

magno from contra eye

Question 30

layer 2 of LGN gets input from:

Answer 30

magno from ipsi eye

Question 31

layer 3 of LGN gets input from:

Answer 31

off center parvo from ipsi eye

Question 32

layer 4 of LGN gets input from:

Answer 32

off center parvo from contra eye

Question 33

layer 5 of LGN gets input from:

Answer 33

on center parvo from ipsi eye

Question 34

layer 6 of LGN gets input from:

Answer 34

on center parvo from contra eye

Question 35

what kind of cells send input to first 3 konio layers in LGN?

Answer 35

movement sensitive cells

Question 36

what kind of cells send input to 4th and 5th konio layers in LGN?

Answer 36

short wavelength konio cells

Question 37

name 4 inputs to LGN:

Answer 37

retina
midbrain-alter gain
intralaminar nuclei of LGN
striate cortex-layer 6 main input to LGN

Question 38

In the striate cortex, we start off with more neurons during development, as we age they atrophy unless they are given strong input. This supports the concept that expansion of cells for central visions serves a function of:

Answer 38

visual attention

Question 39

striate cortex mainly gets input to:
where do magno layers go?
parvo layers?

Answer 39

layer 4:

• magno: central part of layer 4 (and layers 5 and 6)
• parvo: top and bottom of layer 4 (striate)

Question 40

areas of striate cortex that receive inputs from parvo send output to:

Answer 40

layers 2 and 3 of striate cortex

Question 41

layer 6 of striate cortex sends ouputs where?

Answer 41

LGN ONLY (inhib)

Question 42

layer 5 of striate cortex sends ouputs where?

Answer 42

sup colliculus, pretectum (excitatory)

Question 43

each column in striate cortex represents:

Answer 43

each column represents a specific place in the VF and dominance by one eye

Question 44

class 3 cells are located in what layer? what kind of receptive fields?

Answer 44

layer 3 of striate cortex, color specific cells
large messy receptive fields (receive info from many dominance columns)
very specific to color info, but not spatial info, (so no center surround, but still red on green off)

Question 45

class 1 cells are located in what layer? what kind of receptive fields?

Answer 45

lose colour, but have spatial info; “line detectors” all sensitive to same orientation in column