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

Question

What are the early origins of behavioral neuroscience?

Answer 1

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

Answer 2

contemporary techniques identify molecular, neurochemical, and morphological differences among neuronal types how these differences contribute to behavior

Answer 3

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

Answer 4

researchers learned to label neurons and their connections + glial cells Brainbow: dye specific glial cells based on different chemicals

Answer 5

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

Answer 6

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

Answer 7

the objective study of animal behavior, especially under natural conditions animal learning and ethology provide the basis for modern behavioral neuroscience

Answer 8

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

Answer 9

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

Answer 10

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

Answer 11

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

Answer 12

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

Answer 13

automated touchscreen tools cognitive and motivational testing programmed to deliver tests less stressful to the rat

Answer 14

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

Answer 15

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

Answer 16

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.

Answer 17

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

Answer 18

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

Answer 19

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

Answer 20

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

Answer 21

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

Answer 22

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

Answer 23

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

Answer 24

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

Answer 25

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

Answer 26

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

Answer 27

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

Answer 28

single-cell recording electroencephalography (EEG) event-related potentials (ERP) magnetoencephalography (MEG)

Answer 29

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

Answer 30

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

Answer 31

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

Answer 32

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

Answer 33

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

Answer 34

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

Answer 35

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

Answer 36

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

Answer 37

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

Answer 38

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

Answer 39

detects the directional movements of water molecules to image nerve giber pathways in the brain used to delineate abnormalities in neural pathways

Answer 40

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

Answer 41

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

Answer 42

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

Answer 43

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

Answer 44

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

Answer 45

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

Answer 46

relatively easy to hook up can record short periods of activation

Answer 47

light doesn't penetrate deeper brain tissue, restricted to cortex spatial resolution poorer than fMRI

Answer 48

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)

Answer 49

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

Answer 50

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

Answer 51

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

Answer 52

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

Answer 53

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

Answer 54

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

Answer 55

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

Answer 56

do animals actually contract the same neurological diseases as humans? how ethical is it to use animals in research?

Answer 57

some disorders are easy to model (eg stroke) behavioral disorders are more difficult

Answer 58

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

Answer 59

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

Answer 60

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