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PSYCH 454 > BRAIN NETWORKING > Flashcards

BRAIN NETWORKING Flashcards

1
Q

Striatum of Basal Ganglia

A

putamen and caudate nucleus

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2
Q

Basal ganglia contributes to:

A

– Action selection
– Reinforcement learning

Nearly all of the cerebral cortex projects to the striatum except for the primary visual cortex and primary auditory cortex

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3
Q

Increased striatal activity can disinhibit thalamus (via direct pathway)

A

Striatum inhibits GP internal segment, which removes inhibition of thalamus

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4
Q

Hyperdirect pathway

A

cortex to subthalamic nucleus

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5
Q

Direct pathway

A

striatum to GP internal segment

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6
Q

Indirect pathway

A

Striatum to GP external segment to subthalamic nucleus to GP internal segment

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7
Q

Cerebellum plays a role in more automatic execution during/after skill learning

A

Cerebellum involved in both motor and cognitive functions

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8
Q

Cerebellum receives copies of commands from motor and prefrontal cortex

A

Copies of commands called “efference copies”

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9
Q

Cerebellum may output predicted sensory consequence of movements?

A

Cerebellum may predict new state of body based on efference copy?

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10
Q

Hippocampus functions

A

– Episodic memory
– Spatial navigation

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11
Q

Parahippocampal areas

A

parahippocampal cortex,
perirhinal cortex, entorhinal cortex

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12
Q

“Six degrees of separation”

A

Idea that everyone can be connected in ≤ 6 steps

“The small world problem”

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13
Q

Regular network

A

Every node (dot above) connected to its nearest neighbors (nearby dots)

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14
Q

Random network

A

Increase disorder by reconnecting edges to random nodes until all edges are wired randomly

Connection is called “edge”

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15
Q

Small-world network

A

High clustering like regular graph, yet small characteristic path length (Global average of all distances) like random graph

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16
Q

Module

A

a subset of nodes with high within-module connectivity and low inter-module connectivity

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17
Q

Path length

A

minimum number of edges to go from one node to another

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18
Q

Node degree

A

Number of connections that link a node to the rest of the network

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19
Q

Clustering coefficient

A

Number of connections that exist between nearest neighbors of a node (as a proportion of the maximum number of possible connections)

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20
Q

Rich-club architecture

A

Type of small world network evident in the brain

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21
Q

Rich node

A

Node with a large number of connections, i.e., high-degree node (called network hub)

22
Q

Rich club

A

Rich nodes that are well-connected with each other, forming a tight subgraph

23
Q

Rich-club organization

A

Greater likelihood of high-degree nodes forming clubs than low-degree nodes

24
Q

Anatomical connections

A

– Axon projects from one neuron to another
– Parallel projections of axons form white matter paths in the brain

25
Q

How to measure anatomical connections

A

– Tracer studies (invasive): Tracer molecule injected into brain and travels along axons
– Diffusion MRI (non-invasive): Infer direction of white matter path based on water diffusion

26
Q

Functional connections

A

– Correlated neural activity between different brain areas
– Functional connection may reflect direct or indirect anatomical path between brain areas

27
Q

How to measure functional connections

A

– Statistical dependencies: correlation, coherence (correlation between oscillation frequencies)…
– Can measure functional connections based on spike rate, local field potentials, EEG, functional MRI (BOLD activity)

28
Q

Diffusion MRI

A

Water diffuses more readily along connections between brain areas
Measure water diffusion in each brain voxel
Connect voxels based on preferred diffusion directions

Diffusion MRI techniques include DTI or diffusion tensor imaging

29
Q

Functional MRI

A

Parcellate brain into regions of interest (ROIs)
Calculate correlation between BOLD activity in two ROIs
Repeat correlation calculation for all possible pairs of ROIs

30
Q

Resting-state functional MRI

A

Subject scanned with no behavioral task

Functional connectivity is time-dependent and modulated by task context

31
Q

Schizophrenia

A

characterized by delusions, hallucinations, disorganized speech, other symptoms that cause social or occupational dysfunction

32
Q

position invariance

A

can identify an object no matter where it is

Sensor with big receptive field

33
Q

How to operate effectively on multiple spatial scales?

A

– How to localize and identify small objects or parts of objects?
– How to identify big objects or scenes?
– How to identify objects wherever they are (position invariance)?

34
Q

topographic maps

Multiple representations of the environment

A

– Representation of our environment built from small receptive fields
– Representation of our environment built from big receptive fields
– Representation of the environment built from different stimulus features, e.g., motion
– Orderly representation of sensory space
– Different neurons have receptive fields covering different parts of sensory space
– Neurons arranged such that nearby neurons represent nearby regions of sensory space and distant neurons represent distant regions of sensory space

35
Q

How to build receptive fields of different sizes?

A

– Small receptive fields usually found at early stages of sensory pathways near sensory organs
– Bigger receptive fields can be built from small receptive fields
– If neurons with small, adjacent receptive fields all provide input to the same neuron, then summing these inputs will produce a bigger receptive field

36
Q

Somatosensory RF

A

– area of body surface
– smallest RFs for finger tips
– largest RFs for thigh/calf

Mapped along dimensions of body surface

37
Q

Visual RF

A

– area of visual space
– smallest RFs only a few minutes of arc (like dot on page)
– largest RFs tens of degrees (like entire page of book)

Mapped along (usually 2) dimensions of the space around you

38
Q

receptive fields (RFs)

A

part of sensory world to which neuron responds

39
Q

Olfactory receptive field

A

Mapped along dimension of carbon chain length of odorant

40
Q

Numerical receptive field

space on an abstract scale

A

Found in some parietal and prefrontal neurons

Mapped along dimension of numerosity

41
Q

big receptive fields

A

– to identify objects
– for position invariance

42
Q

small receptive fields

A

– to identify detailed features of an object
– for high acuity

43
Q

Fovea

A

part of retina with high spatial resolution
– Certain parts of sensory space may occupy disproportionately large part of map, e.g., fovea
– This allows greater sensitivity for those parts of sensory space

central part of visual field

44
Q

Brain areas commonly defined by their representation of sensory space

A

– Sensory space is mapped multiple times in the brain
– E.g., there are multiple visual maps of the space around us
– Each distinct visual brain area (V1, V2, etc) contains a complete representation of half of visual space (called “hemifield”)
– I.e., visual area in left hemisphere predominantly represents right visual field (and vice versa)

45
Q

Retinotopic map

A

– orderly representation of visual space (hemifield)
– called “retinotopic” as it reflects organization of retina

Hemifield = half of visual space

46
Q

Tonotopic map

auditory brain areas

A

orderly representation of sound (tone) frequency

47
Q

Somatotopic map

A

orderly representation of body surface

48
Q

Efficient design to group neurons together that are highly interconnected

A

– Neurons processing nearby sensory space will interact more often (than with other neurons)
– Grouping these neurons together reduces wiring

49
Q

connections within a map?

A

– Each neuron in a map is connected with a subset of the other neurons
– If the number of connections of each neuron is held constant, then the proportion of the map that each neuron connects with depends on the number of neurons in the map

50
Q

Large number of neurons in fine-grained maps

small RFs

A

– Each neuron requires more and longer connections?
or
– Each neuron connects with fewer neurons?

51
Q

Fewer neurons in coarse-grained map

big RFs

A

– Neurons representing distal parts of the map more readily connected
– Facilitates comparison/integration of information from different parts of the map

PSYCH 454 (15 decks)

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