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Organ Systems III by Robin > Thalamus & Cerebral Cortex > Flashcards

Thalamus & Cerebral Cortex Flashcards

1
Q

How many cell layers comprise the cerebral cortex?

A

six

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2
Q

What do the 6 cell layers of the cerebral cortex do?

A

1) receive incoming information 2) form meaningful spatiotemporal patterns 3) project information

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3
Q

To where does the cerebral cortex project information?

A

other cortical areas, limbic system, brain stem, spinal cord

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4
Q

Name the layer IV cell type, and their source of incoming information

A

Stellate cells; from the Thalamus

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5
Q

Name the layer V cells, and their action

A

Pyramidal cells; project info to other regions of CNS

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6
Q

True or False: Interneurons are part of the neural excitatory circuitry

A

True, but incomplete: they also form circuits for inhibitory pathways

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7
Q

What are Brodman’s areas, how are they identified, and what is their purpose?

A

cortical regions of histologically similar/ distinguishale cells. Each area is numbered. Brodman’s areas are a tool for anatomically mapping functional activity.

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8
Q

What is the purpose of fMRI imaging?

A

It allows us to view real time human brain activity in vivo

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9
Q

What precisely is visible in an fMRI image?

A

Blood flow, which correlates to neuronal activity

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10
Q

fMRI: scanning ________ provides an overall map of the brain

A

hydrogen ions

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11
Q

fMRI: magnteic gradients permit division of ______ into _____

A

brain; slices

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12
Q

Name the mnemonic for the fMRI measurement

A

BOLD: Blood Oxygen Level Detection

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13
Q

hemoglobin is diamagnetic when oxygenated and paramagnetic when deoxygenated. So what?

A

SO… the degree of oxygenation creates differences in the MR signal. And, neuronal activity uses up oxygen, which stimulates an increase in blood flow

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14
Q

Are there two Thalami, or is there one Thalamus?

A

Two thalami

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15
Q

The Thalami project axons to _________

A

all areas of the cortex

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16
Q

The thalamus is comprised of _______

A

a cluster of nuclei

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17
Q

The VPL and VPM of the thalami project to the ________

A

primary somatosensory cortex

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18
Q

True or false: The primary somatosensory cortex is located in the lateral sulcus and the secondary SS cortex is located in the postcentral gyrus.

A

False; the reverse is true – primary= postcentral and secondary = lateral sulcus

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19
Q

Primary and secondary SS cortices ______ and _______ sensory information into _________

A

elaborate; contextualize; meaningful experience

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20
Q

Match the thalamic region to it’s source of input and nerve(s): VPL VPM body head Trigeminal nerve lemniscal pathway anterolateral pathway

A

VPL: body; dorsal column (lemniscal and anterolateral pathways) VPM: head; trigeminal

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21
Q

True or false: VPL and VPM are just ventro-posterior lateral or medial

A

True – whatever that means ; )

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22
Q

What are in the cortical columns? A. neurons coming from the same body region B. neurons coming from similar receptive fields C. neurons of similar modalities D. all of the above

A

D., all of the above

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23
Q

What is somatotopy?

A

the Homunculus: mapping of varied density of sensory receptors throughout the body onto the cortex. NB, the mapping is contiguous

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24
Q

Where does somatotopy occur?

A

Most areas of the CNS – spinal cord, brain stem, thalami, cerebral cortex

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25
Q

In rodents, when a single whisker is moved, the responding cortical activity spreads from_________ out toward _____________. This spreading is asymetric, and requires_________

A

a specific cortical column; neighboring columns; arcuate fibers

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26
Q

definition: the phenomenon of functional (not anatomical) cortical changes in somatotopy according to experience and learning

A

Cortical Plasticity

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27
Q

True or false: neighboring cortical columns do not respond to input from one-anothers source receptors

A

False: there is interconnection, but the neighbors’ connections are latent

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28
Q

When latent cortical pathways are activated by repetition of an activity, certain areas of the cortex _______, taking over _______

A

expand; other areas

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29
Q

cortical localization of stimulation is associated with the various_______

A

neural levels

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30
Q

Neural levels of cortical localization of stimulation include: A. Somatosensory cortex B. anterolateral column nuclei C. Thalamus D. dorsal column nuclei E. A, C, D only F. B and D only G. A, B, C & D

A

E: SS cortex, Thalamus, Dorsal column nuclei

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31
Q

Why is cortical localization important?

A

It helps the body figure out how to do something

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32
Q

Localization is more specific where the receptiv fields are ______

A

smaller

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33
Q

Peripheral RF’s have _____ differentiation, whereas CNS RF’s are more ________ differentiated.

A

Gross; finely

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34
Q

The purpose of lateral inhibition is…?

A

Refining an input

35
Q

The method of lateral inhibition is…?

A

enhancing the difference(s) between SS RF’s

36
Q

The CNS areas involved in lateral inhibition are…?

A

Cortex, thalamus, dorsal column nuclei (DCN)

37
Q

How does the DCN distinguish between excitation that is signaled from the center of an RF, and inhibition signaled from the periphery of an RF?

A

Inhibitory interneurons lie between the peripheral RF and the DCN

38
Q

The main players in lateral inhibition are…?

A

Inhibitory interneurons

39
Q

Without lateral inhibition, a single sensory neuron will _____ and activate _______ local DCN neurons. This diffuses the intensity of the _________, as it is spread out

A

branch; several; stimulus

40
Q

Clinically, what does two-point discrimination – stimulating separate receptive fields – help to measure or assess?

A

the integrity of the dorsal column-lemnscal system.

41
Q

Name a disease that causes dorsal column degeneration, thereby reducing two-point discrimination

A

Syphilis – patients lose Meissners, Pacinians, Ruffinis

42
Q

Adequate two=point discrimination depends on two things. What are they?

A
  1. The density of sensory discriminitive touch mechanoreceptors in the particular area of skin 2. Lateral inhibition in the CNS for fine discrimination
43
Q

What do VPL and VPM stand for?

A

Ventropostero lateral nucleus; ventropostero medial nucleus (of the Thalamus)

44
Q

Feeling for one’s keys in one’s purse is an example of…?

A

Cortical regulation of lateral inhibition of DCN: feedback control helps to focus on specific sensory stimuli

45
Q

During tactile exploration, descending pathways from _____ and _______ modulate ______ input from the upper limb.

A

Primary SS; motor cortex; afferent

46
Q

SS perception depends on _______. Motor cortex sends messages to muscle for _______, AND to DCN neurons to utilize sensory stimuli related to the ______

A

movement; movement; movement

47
Q

Brodmann’s area 3b has separate cortical columns for _____ rapid adapting and ______ slow adapting stimuli.

A

Meissner’s; Merkel’s

48
Q

Signals from Brodmann’s 3a and 3b converge and transfer to ______

A

areas 1 and 2

49
Q

neurons generate more abstract SS perceptions (orientation, motion, spatial arrangements) in ______

A

areas 1 and 2

50
Q

SS and visual signal converge in Brodmann’s area_____, which is the______. This creates _______ space.

A

5; posterior parietal association cortex; body-centered

51
Q

Brodmann’s 1, 2, 3a, 3b all project to_______

A

Secondary SS (S-II)

52
Q

Global properties of an object – such as size, shape – are perceived by multiple points of contact being compared to ________ representations of objects. These points of contact include areas of ______, _______, and ________

A

previously stored; joints; muscles; skin stretch

53
Q

What is the order of the cortical hierarchy (of Brodmann’s areas) – low to high?

A

3b -> 1 -> 2 -> 5; 3b can also go directly to 2

54
Q

What is the relationship of RF’s within the cortical hierarchy (of Brodmann’s areas)?

A

RF’s enlarge going up

55
Q

The larger RF’s at the “top” of the cortical hierarchy (of Brodmann’s areas) are integrated into_______

A

“meaningful wholes”

56
Q

Match the following: Ventral stream Dorsal stream S-I projects to S-II bilaterally S-I projects to Posterior Parietal Cortex (PPC)/ areas 5 & 7 How? What is it? Where? Form processing multisensory integration tactile object recognition positioning hand to grab an object global features of objects (size, shape) directing attention interacting with motor cortex

A

Ventral stream: S-I projects to S-II bilaterally; What is it?; Form processing; global features of objects (size, shape); tactile object recognition Dorsal stream: S-I projects to Posterior Parietal Cortex (PPC)/ areas 5 & 7; multisensory integration; positioning hand to grab an object; directing attention; interacting with motor cortex

57
Q

definition: the combined orientation of edges on different fingers produce the perception of holding a Barrel of Monkeys

A

Orientation Selectivity (the domain of S-II)

58
Q

S-II (ventral stream) responses depend on (choose all that apply): A. Behavioral context B. Number of receptors C. Limbic system memories D. Motivational state E. Speed of incoming stimuli

A

A, C, D. (S-II communicates with the Hippocampus and Amygdala)

59
Q

Name the two routes for information to travel from S-I and S-II to the PPC/ association cortices

A
  1. directly, via arcuate fibers 2. indirectly, via the Thalami
60
Q

The Posterior Parietal Association Cortex is where _____ begins

A

consciousness!!

61
Q

True or false: the PPC integrates touch, proprioception and audition to form a coherent representation of space, coded in a body-centered reference frame

A

False: No audition; add vision. All the rest is true

62
Q

The body-centered reference frame of the PPC is based on which of these (choose all that apply)? A. Body schema B. Peripersonal space C. Egocentric space

A

All three

63
Q

The activity of the PPC extends into Wernicke’s area, addressing the somatosensory aspects of _____ and _____

A

reading; writing

64
Q

the body schema/ egocentric space is dependent on______, while peripersonal space is dependent on_____

A

proprioception; vision

65
Q

True or false: the body schema/ egocentric space assists our body awareness, embodiment of sensory experiences, and spatial organization (planning and execution) of action

A

All true

66
Q

the body schema/ egocentric space is ________during body movement

A

unconsciously updated

67
Q

Visual, auditory and somatosensory input converge/ are projected to multiple areas of the brain. Name three and suggest the use of these sensations in each

A
  1. posterior/ inferior parietal association cortex; beginig of consciousness 2. Limbic regions; generate memory and emotions 3. Prefrontal cortex (PFC); evaluate behavior(s)
68
Q

Where are lesions that lead to Neglect Syndrome located?

A

Right inferior parietal, especially the angular gyrus

69
Q

What is lost in Neglect Syndrome?

A

Left side body awareness & visual fields

70
Q

What book did Oliver Sacks write, on Neglect Syndrome?

A

“The Man who Mistook his Wife for a Hat”

71
Q

definition: the inability to identify an object via the sense of touch

A

Astereognosis

72
Q

What is the order of bottom-up SS input?

A

sensory receptors -> S-I neurons, S-II, visual, asociation cortex, auditory association cortex -> PPC

73
Q

What is the order of top-down SS input?

A

PPC and motor cortices -> SS-I

74
Q

what mechanism is associated with the “remembered present’?

A

top-down feedback, which extends the sensation slightly beyond the length of the stimulus

75
Q

Phantom limb experiences arise from the disassociation of ________ from _______

A

Somatoperception (how the body feels); somatorepresentation (belief/ attitude about one’s body, or other’s bodies)

76
Q

Phantom limb arises when a denervation of the limb cortex unmasks _________ sensory pathways from ______ areas of the body (think cortical columns)

A

latent; contiguous

77
Q

When a person loses a limb or portion of a limb, the homunculus in the cortex is eventually re-organized with a reduced density of proximal structures. This leads to what erroneous perception?

A

Telescoping, where the person feels that their foot is closer to their knee, for example

78
Q

Phantom limb pain does not respond to opiates. Why not?

A

because the phantom phenomenon is associated with S-I, which has no opiod system

79
Q

True or false: one possible mechanism of phantom limb pain is that efferent pathways get ‘stuck’ in a perception of the limb in a tightly contracted posture

A

true

80
Q

What simple tool has helped some patients who suffer from phantom limb pain?

A

The mirror box

81
Q

What does the Rubber Hand Illusion test?

A

Body ownership – coherence of multisensory representation of cortical areas of touch, vision, proprioception.

82
Q

Describe the Rubber Hand Illusion

A

when a person sees a rubber hand being stimulated at the same time that their unseen actual hand is similarly stimulated, the rubber hand becomes part of their body – creepy!

83
Q

Activity in which part(s) or the cortex account for the Rubber Hand Illusion phenomenon?

A

Posterior Parietal and premotor

84
Q

definition: the delusion of being infested with bugs or parasites, possible caused by a disruption in prefrontal control over SS representations.

A

Delusional parasitosis

Organ Systems III by Robin (2 decks)

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