Chapter 7 Flashcards

Question

Recording action potentials from single cells

Answer 1

Measuring single-neuron AP’s with fine electrodes: Electrodes placed next to cells (extracellular recording) or inside them (intracellular recording) Extracellular recording techniques make it possible to distinguish activity of up to 40 neurons at once Intracellular recording allows study and recording of a single neurons electrical activity

Answer 2

Used to discover ‘place cells' → code the spatial location of the animal and contribute to a spatial map of the world in the brain Showed neurons in the rat and mouse hippocampus vigorously fired when an animal was n a specific place in the environment

Answer 3

measures the summed graded potentials from thousands of neurons → excitatory and inhibitory Reveals features of the brains electrical activity ↳ changes as behavior changes ↳recorded from cortex: displays rhythmical patterns ↳ living brains electrical activity is never silent Pyramidal cells → outer edge of cortex

Answer 4

Activity from EEG can help uncover now perception works → stimuli vs. EEG reaction Awake or excited: shorter length shorter amplitude Relaxed, eyes closed: Alpha rhythms generated Drowsy: slowed frequency, increased amplitude Asleep: slower, higher amplitude waves Deep sleep: even slower and higher amp. REM: noticed after a while, sleep looked like person was awake → when dreaming, EEG reflects waking patterns

Answer 5

Largely the graded potentials on dendrites that sensory stimulus triggers Complex electroencephalographic waveforms are related in time to a specific event To counter noise effects, the stimulus is presented repeatedly and recorded responses are averaged

Answer 6

In averaging process for auditory ERP→ tone is presented at time 0, and EEG activity in response is recorded After many successive presentations of the tone, EEG wave sequence develops distinctive shape ↳ becomes very clear after 100 responses are averaged Positive and negative waves that appear at different times after the stimulus presentation are used for analyses

Answer 7

Non invasive → not penetrating brain/skull Cost effective → commercially available EEG’s Can record hundreds of sites High temporal resolution → tell changes in very short time frame Poor spatial resolution Can't record deep brain regions → only cortical events result in firing of pyramidal cells

Answer 8

Neural activity has electrical field and produces a magnetic field→spatial resolution = good Magnetic potentials are recorded from detectors placed outside the skull → permit 3D localization of cell groups generating measured field → Higher resolution than ERP High cost

Answer 9

Only shows structure (no functioning levels) → CT scans, MRI, DTI, MRS, etc. fMRI → Brain functioning and imaging MRI → just structure/location

Answer 10

Xray beams passed through brain at many different angles → creates many images Images are combined with mathematical techniques to create 3D image of brain Dense skull forms white border→ gray matter and white matter density does not differ enough to distinguish between two: cortex and white matter shows up as homogenous gray Ventricles can be visualized because fluid in them is far LESS dense → darker image → Major fissures in cortex also rendered darker

Answer 11

Produces a static, 3d, brain image by passing strong magnetic field through brain → followed by a radio wave → then measures radiation emitted from Hydrogen atoms Increased demand of blood flow due to increased activity→ measure radiation from H atoms in the blood

Answer 12

Defects directional movement of H2O molecules to image nerve fiber pathways Used to delineate abnormalities in neural pathways ↳ find connective pathways

Answer 13

MRI method: uses hydrogen proton signal to determine the concentration of brain metabolites Useful in detecting persisting abnormalities in brain metabolism in disorders such as concussion → using MRS you can find agents of infectious disease, metabolic disease, etc.

Answer 14

When 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 blood flow OR levels of the bloods constituents, such as oxygen, glucose, and iron

Answer 15

Active neurons use more oxygen → increase blood carbon dioxide levels, which signal blood vessels to dilate, increasing blood flow and bringing more oxygen to the area ↳ oxygen levels in activated brain area increases Changes in oxygen content in blood alters the magnetic properties of the water in blood → oxygen rich hemoglobin = less magnetic than oxygen-poor hemoglobin MRI could accurately match these changes in magnetic properties to specific brain locations fMRI allows good spatial resolution on brain activity's source

Answer 16

Dense blood vessel supply to cerebral cortex allows for a spatial resolution of fMRI on the order of 1 mm Changes in blood flow take 1/3 second → poorer temporal resolution relative to EEG Extremely restrictive to subject Must stay motionless

Answer 17

Form of optical tomography → functional Technique operates on principal that object can be reconstructed by gathering light transmitted through it Reflected infrared light is used to determine blood flow because oxygen-rich hemoglobin and oxygen-poor hemoglobin differ in absorption spectra Different levels of blood flow = different levels of activity → light absorption changes based on O2 consumption Biological tissue (brain) can absorb light → properties of tissue determine how MUCH light is absorbed By measuring bloods light absorption→ can also measure average oxygen consumption (like fMRI) In fNIRS, an array of optical transmitter and receiver pairs are fitted across scalp Overview: changes in tissue (blood flow) → tissue becomes swollen → sensor that emits light bounces MORE light → longer time to reach detector = more activity Easy to hook up and can record short periods of activation → good temporal resolution Light doesn't penetrate deeper brain tissue → restricted to cortex Spatial resolution poorer than fMRI

Answer 18

Indirect way to measure 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 → foreign isotope flows with blood to activated area Radioactive isotope oxygen-15 are very unstable ↳ break down in just a few minutes: relatively safe Radioactive 15O molecules release tiny positively charged subatomic particles known as positrons Positrons are attracted to negatively charged electrons in brain → collision of 2 particles causes release of energy (photons) Energy leaves the head at the speed of light which is detected by PET camera → can target source of energy release

Answer 19

Can detect decay of hundreds of radiochemicals and allows mapping of a wide range of brain changes and conditions Can detect relative amounts of a given NT, the density of receptors, and metabolic activities associated with learning, brain poisoning, and degenerative processes Widely used to study cognitive function

Answer 20

Neurons are regulated by genes that encode the synthesis of particular proteins within cells Genes control the cells production of chemicals within the nucleus ↳ changes that happen within cell can change genes and chemicals → changes behavior Brain contains a wide mixture of chemicals ↳ abnormalities in these chemicals leads to disruptions in behavior ↳ low serotonin production correlated with depression

Answer 21

Technique used to determine the chemical constituents of extracellular fluid Catheter with semipermeable placed in brain → fluid flows in and passes along membrane → diffusion drives passage of molecules across membrane →fluid with molecules exits brain in tubes and collected for analysis

Answer 22

Ability to relate the alleles of specific genes to behaviors Met allele: associated with 11% reduction in hippocampal volume and poorer memory for specific events → episodic memory (associated with high incidence of dementia later in life) Val allele: carriers have better episodic memory but higher incidence of anxiety disorders Two alleles produce different phenotypes: they influence brain structure/function differently

Answer 23

Genes expressed differently in response to environment and experience Epigenetic changes can persist throughout a lifetime and even across multiple generations Wide range of experimental factors → chronic stress, trauma, drugs, culture, and disease: cumulative experiences affect how genes work Epigenetic changes may be related to better stroke recovery

Answer 24

Some focus on Morphology → structure in postmortem tissue Some focus on ways neurons generate electrical activity in relationship to behavior →EEG Some focus on functional changes in brain activity during specific types of cognitive processing →PET and fMRI Considerations: - Temporal resolution (how quickly the measurement or image is obtained) - Spatial resolution: how accurate localization is in the brain - degree of invasiveness

Answer 25

Studying audition → study using EEG: high temporal resolution as response to sound happens quickly Studying tumor → use CT or MRI or fMRI: good spatial resolution to localize where injury is PET→ disadvantage: radioactive tracer must be made in own lab and administered immediately (very unstable: expensive) EEG → cheap and good temporal resolution

Answer 26

Proposed as a good model for ADHD research Known abnormalities in prefrontal dopaminergic supply that correlate with behavioral abnormalities such as hyperactivity DA agonists such as methylphenidate (ritalin) can reverse behavioral abnormalities → both children with ADHD and in SHR rats

Answer 27

Only use animals if it promises to contribute and develop helpful knowledge Optimal care → neglect can skew results Use of animals is public and justified Use only if demonstrated there is no other method that will work