Chapter 7: Methods of Studying the Brain's Structures and Functions Flashcards

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1
Q

Functional Near-Infrared Spectroscopy (fNIRS)

A

noninvasive technique that gathers light transmitted through cortical tissue to image oxygen consumption, form of optical tomography

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2
Q

Neuropsychology

A

study of relationships between brain function and behavior, especially in humans

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3
Q

Behavioral Neuroscience

A

study of the biological bases or behavior in humans and other animals

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4
Q

Stereotaxic Apparatus

A

surgical instrument that permits a researcher or neurosurgeon to target a specific part of the brain

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5
Q

Compensation

A

following brain damage, the neuroplastic ability to modify behavior from that used prior to damage

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6
Q

Deep Brain Stimulation (DBS)

A

neurosurgery in which electrodes implanted in the brain stimulate a targeted area with a low-voltage electrical current to produce or facilitate behavior

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7
Q

Transcranial Magnetic Stimulation (TMS)

A

procedure in which a magnetic coil is placed over the skull to stimulate the underlying brain, used either to induce behavior or to disrupt ongoing behavior

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8
Q

Synthetic Biology

A

design and construction of biological devices, systems, and machines found in nature

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9
Q

Chemogenetics

A

transgenic technique that combines genetic and synthetic drugs to activate targeted cells in living tissue

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10
Q

Place Cells

A

hippocampal neurons maximally responsive to specific locations in the world

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11
Q

Electrocorticography (ECoG)

A

graded potentials recorded with electrodes placed directly on the surface of the brain

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12
Q

Alpha Rhythm

A

large, extremely regular brain waves with a frequency ranging from 7 to 11 Hz, found in most people when they are relaxed with eyes closed

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13
Q

Event-Related Potential (ERP)

A

complex electroencephalographic waveform related in time to a specific sensory event

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14
Q

Magnetoencephalogram (MEG)

A

magnetic potentials recorded from detectors placed outside the skull

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15
Q

Computed Tomography (CT)

A

x-ray technique that produces a static three-dimensional images (called a CT scan) of the brain in cross section

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16
Q

Magnetic Resonance Imaging (MRI)

A

technique that produces a static three-dimensional brain image by passing a strong magnetic field through the brain, followed by a radio wave, then measuring a radio-frequency signal emitted from hydrogen atoms

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17
Q

Diffusion Tensor Imaging (DTI)

A

magnetic resonance imaging method that can image fiber pathways in the brain by detecting the directional movements of water molecules

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18
Q

Magnetic Resonance Spectroscopy (MRS)

A

magnetic resonance imaging method that uses the hydrogen protein signal to determine the concentration of brain metabolites, used to identify changes in specific markers of neuronal function, which is promising for accurate diagnosis of traumatic brain injuries

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19
Q

How do we study the brain’s structure and functions?

A

measuring and manipulating brain and behavior

measuring the brain’s electrical activity

anatomical imaging techniques: CT and MRI

functional brain imaging

chemical and genetic measures of brain and behavior

comparing neuroscience research methods

using animals in brain-behavior research

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20
Q

What is functional near-infrared spectroscopy (fNIRS)

A

non-invasive technique that gathers light transmitted through cortical tissue to image oxygen consumption

form of optical tomography

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21
Q

What is shown in the fNIRS of babies exposed to language?

A

when babies were exposed to words of their parent’s language a specific pattern of activation emerges

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22
Q

What processes were involved in twentieth century neuroscience?

A

lesions and localization of function: observing how people or animals with head injuries act

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23
Q

What is neuropsychology?

A

study of the relationships between brain function and behavior

emphasis on humans

measuring brain and behavior includes noninvasive imaging, complex neuroanatomical measurement, and sophisticated behavioral analyses

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24
Q

What are the origins of neuropsychology?

A

Paul Broca discovered the link between specific damage located in the left frontal lobe region and language difficulties (1863)

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25
Q

What are the early origins of behavioral neuroscience?

A

techniques for neuroanatomy

histological: brains sectioned postmortem and tissue stained with different dyes (early 20th century)

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26
Q

What do contemporary techniques in behavioral neuroscience involve?

A

contemporary techniques identify molecular, neurochemical, and morphological differences among neuronal types

how these differences contribute to behavior

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27
Q

What were brain imaging techniques in the early 20th century?

A

light microscopic techniques allowed researchers to divide the cerebral cortex into many distinct zones based on the characteristics of neurons in those zones

researchers presumed cortical zones had specific functions

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28
Q

What were brain imaging techniques in the early 21st century?

A

researchers learned to label neurons and their connections + glial cells

Brainbow: dye specific glial cells based on different chemicals

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29
Q

What are the characteristics of modern day methods of brain imaging?

A

prioritize greater resolution and specificity

visualize living tissue instead of dead tissue

can visualize neuron’s structures

visualize synapses in 3D detail

can mount a telescope on the head of a mouse

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30
Q

How do modern techniques allow for the study of anatomy and behavior?

A

learning example

learning is correlated with neuroanatomical changes (modification of synaptic organization of specific neurons, where and how new synaptic connections were made)

modern techniques allow researchers to track these specific anatomical changes

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31
Q

What is ethology?

A

the objective study of animal behavior, especially under natural conditions

animal learning and ethology provide the basis for modern behavioral neuroscience

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32
Q

What is the neuropsychological testing of humans?

A

the brain can control a wide range of functions (movement, perception, emotion)

any analysis of behavior must be tailored to the particular functions under investigation

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33
Q

How are memory disturbances measured?

A

memory is not a single function (memory for events, colors, names, places, and motor skills)

it is rare for someone to be impaired in all forms of memory, so each must be measured separately

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34
Q

Why are rats used in the study of behavioral neuroscience?

A

rats have very large behavioral repertoires

can be independently examined

can study the neural bases on sensation, cognition, memory, movement, etc.

using mazes and other tests

35
Q

What was the swimming pool tasks experiments on rats?

A

Richard and Morris (1981), navigation task

place learning: rat must find platform using external cues

matching-to-place learning: platform is in a different location each day

landmark version: platform is identified by a cue on the pool walls

36
Q

What was the skill reaching task involving rats?

A

rats were trained to reach through a slot to obtain food

movements can be broken down into segments, which are differently affected by different types of neurological perturbation

can be used to learn about deficits in fine movement induced by strokes

37
Q

How are automated touchscreen platforms used to study rats?

A

automated touchscreen tools

cognitive and motivational testing

programmed to deliver tests

less stressful to the rat

38
Q

How is manipulation of brain-behavior interactions used to study the brain?

A

we can manipulate some aspect of brain function and see how behavior changes

manipulation helps in developing hypotheses about how the brain affects behavior and then test the hypotheses

manipulation helps in developing animal models of neurological and psychiatric disorders

using techniques such as drugs and electrical stimulation to activate the brain and lesions to inactivate them

animals can be manipulated using diets, social interaction, exercise, sensory stimulation, etc

39
Q

What are brain lesions?

A

the first (and simplest) technique used for brain manipulation is to ablate (remove or destroy) tissue

used by Karl Lashley (1920s) to fins location of memory in the brain

Scoville removed the hippocampus from H.M. to treat epilepsy, but produced amnesia instead

40
Q

What is a stereotaxic apparatus?

A

surgical instrument used to target a specific part of the brain

allows the precise positioning of all brain regions relative to each other and to landmarks on the skull

used to destroy specific brain regions or to locate areas to inject drugs, etc.

41
Q

What is compensation?

A

the neuroplastic ability to modify behavior from that used prior to the damage

to avoid compensation following permanent lesions, temporary and reversible lesion techniques are used

regional cooling prevents synaptic transmission: hollow metal coiled placed next to brain structure, chilled fluid cools brain region to prevent synaptic transmission

local administration of a GABA agonist increases local inhibition

42
Q

How is brain stimulation used to study brain function?

A

the brain operates on both electrical and chemical energy

it is possible to selectively turn brain regions on or off by using electrical or chemical stimulation

now we can use stereotaxic instruments to place electrode or cannula in specific brain regions

goal: enhancing or blocking neuronal activity and observing behavioral effects

43
Q

How is brain stimulation used on rats?

A

rats with electrodes in the lateral hypothalamus eat whenever the stimulation is turned on

self-stimulation: given the opportunity, rats will press a lever to obtain the current

the stimulation affects a neural circuit involving both eating and pleasure

44
Q

How does brain stimulation improve movement?

A

electrically stimulating the intact cortex adjacent to cortex injured by stroke leads to improvement in motor behaviors

Terskey and colleagues restored motor deficits in a rat model of Parkinson disease by electrically stimulating a specific brain nucleus

45
Q

What is deep-brain stimulation?

A

electrodes implanted in the brain stimulate a targeted area with a low-voltage electrical current to facilitate behavior

used for Parkinson disease, depression, OCD

DBS to the Globus pallidus in the basal ganglia of Parkinson patients makes movements smoother

invasive: holes must be drilled in the skull to attach the electrode in the brain

46
Q

What is transcranial magnetic stimulation (TMS)?

A

procedure in which magnetic coil is placed over the skull to stimulate the underlying brain

a high-voltage current pulsed through the coil produces a rapid increase and subsequent decrease in the magnetic field around the coil

the magnetic field easily passes through the skull and causes a population of neurons in the cerebral cortex to depolarize and fire

used either to induce behavior or to disrupt ongoing behavior

non-invasive

motor cortex stimulation: induces body movements
visual cortex stimulation: participant sees phosphenes

47
Q

How are drug manipulations used to study brain function?

A

drugs can pass into the bloodstream and enter the brain through an indwelling cannula that allows direct application of drugs to specific brain structures

drugs can influence the activity of specific neurons in specific brain regions

because drug effects wear off over time, it is possible to study drug effects on learned behaviors, such as skilled reaching

48
Q

What is synthetic biology?

A

the design and construction of biological devices, systems, and machines not found in nature

techniques include inserting or deleting a genetic sequence into the genome of a living organism

49
Q

What is the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) method?

A

cuts DNA in any cell

used to silence genes by cutting out those regions in the DNA

DNA repair can be tailored to insert a new sequence to replace previous one

50
Q

What is optogenetic?

A

transgenic technique that combines genetics and light to control targeted cells in living tissue

based discovery that light can activate proteins

proteins that occur naturally can be inserted into cells

fiber-optic light can be delivered to selected brain regions such that all neurons exposed to the light respond immediately

great potential for research

high spatial and temporal resolution

ion channels can be placed into specific cell lines and turned on and off on millisecond time scales

51
Q

What are opsins?

A

proteins derived from microorganisms

combine a light-sensitive domain with an ion channel

channelrhodopsin-2 (ChR2): when expressed in neuron and exposed to blue light, ion channels open and depolarizes neuron = excitation

halorhodopsin (NpHR): a green-yellow light activates a chloride pump, hyperpolarizing the neuron = inhibition

52
Q

What are the four major techniques for measuring the brain’s electrical activity?

A

single-cell recording

electroencephalography (EEG)

event-related potentials (ERP)

magnetoencephalography (MEG)

53
Q

What is the process of recording action potentials from single cells?

A

measuring single-neuron action potentials with fine electrodes

electrodes placed next to cells (extracellular recording) or inside them (intracellular recording)

extracellular recording techniques make it possible to distinguish the activity of as many as 40 neurons at once

intracellular recording allows study and recording of a single neuron’s electrical activity

54
Q

What is single cell recording?

A

O’Keefe & Dostrovsky (1971) showed that neurons in the rat and mouse hippocampus vigorously fire when an animal is in a specific place in the environment

these place cells code the spatial location of the animal and contribute to a spatial map of the world in the brain

won a Nobel prize in 2014 for their discoveries of cells that constitute a positioning system in the brain

55
Q

What are EEGs?

A

EEG measures the summed graded potentials from many thousands of neurons

reveals features of the brain’s electrical activity

the EEG changes as behavior changes

an EEG recorded from the cortex displays an array of patterns, some of which are rhythmical

the living brain’s electrical activity is never silent, even when the person is asleep or comatose

56
Q

What are ERPs?

A

largely the graded potentials on dendrites that a sensory stimulus triggers

complex EEG waveforms are related in time to a specific sensory event

to counter noise effects, the stimulus is presented repeatedly, and the recorded responses are averaged

57
Q

How are ERPs detected?

A

in the averaging process for an auditory ERP, a tone is presented at time 0, and EEG activity in response is recorded

after many successive presentations of the tone, the EEG wave sequence develops a distinctive shape that becomes extremely clear after 100 responses are averaged

positive and negative waves that appear at different times after the stimulus presentation are used for analyses

58
Q

What are the advantages and disadvantages of using EEG and ERP?

A

non-invasive
cost
can record from hundreds of sites
high temporal resolution
poor spatial resolution
can’t record deep brain regions

59
Q

What is magnetoencephalography?

A

neural activity, by generating an electrical field, also produces a magnetic field

magnetic potentials are recorded from detectors placed outside the skull

permit a three-dimensional localization of the cell groups generating the measured field

higher resolution than ERP

disadvantage: high cost

60
Q

What is computed tomography (CT scan)?

A

X-ray beams are passed through the brain at many different angles, creating many different images

images are combined with the use of computing and mathematical techniques to create a three-dimensional image of the brain

61
Q

How are brain structures observed through a CT scan?

A

dense skull forms white border

gray matter density does not differ from white matter density enough for a CT scan to distinguish between the two

cortex and its underlying white matter show up as homogeneous gray

ventricles can be visualized because the fluid in them is far less dense

some major fissures in the cortex are rendered darker

62
Q

What is magnetic resonance imaging (MRI)?

A

produces a static, three dimensional brain image by passing a strong magnetic field through the brain, followed by a radio wave, then measuring the radiation emitted from hydrogen atoms

63
Q

What is diffusion tensor imaging (DTI)?

A

detects the directional movements of water molecules to image nerve giber pathways in the brain

used to delineate abnormalities in neural pathways

64
Q

What is magnetic resonance spectroscopy (MRS)?

A

MRI method that uses the hydrogen proton signal to determine the concentration of brain metabolites

useful in detecting persisting abnormalities in brain metabolism in disorders such as concussion

65
Q

What is functional brain imaging?

A

when a brain region is active, the amount of blood, oxygen, and glucose flowing to the region increases

possible to infer changes in brain activity by measuring either blood flow or levels of the blood’s constituents, such as oxygen, glucose, and iron

66
Q

What is functional magnetic resonance imaging (fMRI)?

A

when neurons become active they use more oxygen

active neurons increase blood carbon dioxide levels, which signal blood vessels to dilate, increasing blood flow and bringing more oxygen to the area

the amount of oxygen in an activated brain area increases

changes in the oxygen content of the blood alter the magnetic properties of the water in the blood

oxygen-rich hemoglobin is less magnetic than oxygen-poor hemoglobin

MRI could accurately match these changes in magnetic properties to specific brain locations

fMRI allows for good spatial resolution of the brain activity’s source

67
Q

What are the advantages and disadvantages of fMRI?

A

the dense blood vessel supply to the cerebral cortex allows for a spatial resolution of fMRI on the order of 1 millimeter (very high spatial resolution)

changes in blood flow take 1/3 second, poorer temporal resolution relative to EEG

extremely restrictive to subject

must stay motionless

68
Q

What is functional near-infrared spectroscopy (fNIRS)?

A

form of optical tomography

technique that operates on the principle that an object can be reconstructed by gathering light transmitted through it

optical tomography can image soft body tissue, such as the brain

69
Q

What is optical tomography?

A

reflected infrared light is used to determine blood flow because oxygen-rich hemoglobin and oxygen-poor hemoglobin differ in their absorption spectra

by measuring the blood’s light absorption, it is possible to measure the brain’s average oxygen consumption (just like fMRI)

in fNIRS, an array of optical transmitter and receiver pairs are fitted across the scalp

70
Q

What are the advantages of optical tomography?

A

relatively easy to hook up

can record short periods of activation

71
Q

What are the disadvantages of optical tomography?

A

light doesn’t penetrate deeper brain tissue, restricted to cortex

spatial resolution poorer than fMRI

72
Q

What is positron emission tomography (PET)?

A

imaging technique that detects changes in blood flow by measuring changes in the uptake of compounds such as oxygen or glucose

used to analyze the metabolic activity of neurons

radioactive molecules are injected into the bloodstream (radioactive isotope oxygen-15 are very unstable, break down in just a few minutes, relatively safe)

radioactive oxygen-15 molecules release tiny positively charged subatomic particles known as positrons

positrons are attracted to negatively charged electrons in the brain (collision of the two particles leads to a release of energy)

this energy leaves the head at the speed of light (detected by the PET camera, can target source of energy release)

73
Q

What are the advantages of positron emission tomography?

A

can detect the decay of hundreds of radiochemicals and allows the mapping of a wide range of brain changes and conditions

can detect relative amounts of a given neurotransmitter, the density of receptors, and metabolic activities associated with learning, brain poisoning, and degenerative processes

widely used to study cognitive function

74
Q

What are chemical and genetic measures of brain and behavior?

A

neurons are regulated by genes that encode the synthesis of particular proteins within cells

genes control the cell’s production of chemicals so it is possible to relate behavior to genes and to chemicals inside and outside the cell

the brain contains a wide mixture of chemicals, abnormalities in these chemicals leads to disruptions in behavior, low serotonin production correlated with depression

75
Q

What is microdialysis?

A

technique used to determine the chemical constituents of extracellular fluid

catheter with semipermeable membrane is placed in the brain

fluid flows in, where it passes along the membrane

diffusion drives the passage of extracellular molecules across the membrane

fluid containing the molecules from the brain exits through tubing and is collected for analysis

76
Q

How does measuring genes contribute to studies of brain and behavior?

A

variations in gene sequences contribute to brain organization

studying twins and adopted children allows us to tease apart environmental and genetic contributions to behavior

we can also relate the alleles of specific genes to behaviors

77
Q

What does the Bueller (2006) study tell us about genes affect on brain and behavior?

A

the Met allele is associated with an 11% reduction in hippocampal volume and poorer memory for specific events

Val allele carriers have better episodic memory but higher incidence of anxiety disorders

two alleles produce different phenotypes, they influence brain structure differently

78
Q

What is epigenetics?

A

genes that are expressed can change dramatically in response to environment and experience

epigenetic changes can persist throughout a lifetime and even across multiple generations

wide range of experiential factors: chronic stress, traumatic events, drugs, culture, and disease are factors, cumulative experiences affect how genes work

epigenetic changes may be related to better stroke recovery

79
Q

How are neuroscience research methods compared?

A

some researchers focus on morphology (structure) in postmortem tissue

other investigators focus more on the ways neurons generate electrical activity in relationship to behavior or on functional changes in brain activity during specific types of cognitive processing

considerations: temporal resolution (how quickly the measurement or image is obtained), spatial resolution (how accurate localization is in the brain), degree of invasiveness

studying brain and behavior linkages by perturbing the brain is generally less costly then some imaging methods, many of which require expensive machinery

80
Q

What are two important issue in using animals in brain-behavior research?

A

do animals actually contract the same neurological diseases as humans?

how ethical is it to use animals in research?

81
Q

What are the benefits of animal models of disease?

A

some disorders are easy to model (eg stroke)

behavioral disorders are more difficult

82
Q

What is the Kyoto SHR rat?

A

proposed as a good model for ADHD

known abnormalities in prefrontal dopaminergic supply that correlate with behavioral abnormalities such as hyperactivity

dopamine agonists as as methylphenidate (Ritalin) can reverse behavioral abnormalities, both in children with ADHD and in SHR rats

83
Q

What is the relationship between animal welfare and scientific experimentation?

A

most governments regulate the use of animals in research

universities and other research organizations have additional rules governing animal use

legislation concerning the care and use of laboratory animals in the United States is set forth in the Animal Welfare Act

all accredited North American universities that receive government grant support are required to provide adequate treatment for all vertebrate animals

84
Q

What are the guidelines of the Canadian Council on Animal Care?

A
  1. research needs to contribute and benefit animals and humans
  2. treat the animals well so the results aren’t skewed
  3. public confidence is needed to ensure justified animal use
  4. animals are used only if the researcher’s best efforts to find an alternative have failed