Tony Cog Neuro Part 2

Question 1

History of visual techniques

Answer 1

Henschen 95: used perimeters technique (flash lights to see where in visual field)and post mortem lesions. Damage to upper occipital count see in lower visual field and other way round. If lesion at back, couldn’t see in periphery and if at front, not in centre but wrong as too wide spread. Small lesions in occipital area to map visual field - used ww1 as bullets left brain damage (or infection/death)

Question 2

Visual effects in animal models

Answer 2

Tootell presented stim to monkey then looked at post mortem visual cortex. Used same in humans who had lose use of one eye, found ocular dominance columns. Hyper column is range of properties that relate to a region e.g. orientation of lines. Single unit recordings give insight to functional properties of neurones in layers, columns and blobs

Question 3

Visual regions in mri

Answer 3

Visual field mapping, central activate the back and peripheral activate front. Focus on cross hair, present dynamic moving outwards or in a circle. Diff visual maps measure diff attributes like colour, speed. Apply magnetic fields to disrupt activity in maps to see effect. Lo1 (orientation no shape) and lo2 (shape no orientation- DD)regions unique to humans.

Question 4

The eye

Answer 4

Retina speculates, fovea in macula has only cones so small regions of blindness when light is low. Ppl who only have rods have small regions of blindness from birth (rod achromatopsia). When lights low, gal in visual map but in RA no gap. Macular degeneration in old age leads to blindness, in acquired the cortex doesn’t reside so gal in mpa but no gal for those born W it. Bridge mapped visual cortex , used for ppl that can’t see to determine where visual field is

Question 5

Optogenetics

Answer 5

Switch on cells by turning on light. 2002 found protein that causes algae to move to/away from light as its a light sensitive channel, blue light causes channel to open and ions diffuse in. I the channel rhodopsin could be implanted in nerve cells-control nerves, quicker and more accurate than drugs. Uses GM, take gene and promote into virus, inject virus and is expressed, deliver light by fibre optic cable. Inhibit W halorodopsin and diff colour

Question 6

Uses of optogenetics

Answer 6

Tye: when anxious, mice stay at sides of box and explore when not. Light makes mouse less anxious as affects amygdala.

Question 7

History of neurones

Answer 7

Crick thought light impulses might act as switch. Misenbock inserted genes for microbial rhodopsins into neurones and genes were photosensitive . Use scientific method: Observation, hypothesis, prediction, experimental test

Question 8

Transformations of words

Answer 8

Posner: mind derived multiple representations of stim. Ps responds fastest to phonetic stim suggests we base one representation on physical aspects of stim. Physical aspects activated first like A and a then phonetic like vowel and category last

Question 9

Internal transformations

Answer 9

Sternberg 75: ps given set of letters to memorise then presented with a letter and decide if part of list, measure RT. (Involves encoding, comparing, deciding and responding). If comparison, process can be simultaneous for all items/parallel then RT should be independent but if serial, rt should slow as more time to compare item to list. Found serial as linear increase . Parallel: ps see stim and decide which letters they saw-word superiority as ps id words most

Question 10

Constraints of transformations

Answer 10

Present word list then asked to name colour of each word-easier when word matches colour- stroop

Question 11

Genetic manipulations

Answer 11

Surgeon implants electrodes to modulate nerve activity (deep brain stim). Transcranial direct current stipulation is constant low current to brain via electrodes on scalp, neurones become depolarised so meet threshold under anode opposite under anode so can excite/inhibit. Transcranial alternating stim: current oscillates. Transcranial focused ultrasound is low intensity freq ultrasound which increases channels

Question 12

S and W of genetic manipulations

Answer 12

S: can act as their own controls, limitations: poor spatial resolution so cant make inferences in mind brain relationships , many variables can affect the electrical field and individuals vary in sensitivity

Question 13

Ct and mri

Answer 13

Ct and mri provide 3d images of the brain
Spatial resolutoin of mri is better than ct

Question 14

Measuring neurone activity

Answer 14

Data of firing by neurone called raster plot where each row a single trail and ap is a tick, data in a bar graph called perstimulus histogram. Electrocortiography is a strip of electrodes on brain and , left for a week good resolution as on brain

Question 15

Magnetic resonance spectroscopy

Answer 15

Use mri to measure the chemical composition of tissues as molecules have diff proton compositions. Pet and fmri have poor temp resolution compared to erps pet constrained by decay of isotope. Pet uses 15o as distribution increases in neural regions that are active , tracers can be spec to some tissue

Question 16

Connectivity maps

Answer 16

capture correlated patterns of activity between diff brain regions. From mri data during rest and active
Data from rs- fmri have revealed small set of networks across cerebral cortex and are reliable
Connectivity maps offer new methods for looking at variation between groups

Question 17

Computer models

Answer 17

Use to stim neural networks in order to generate predictions for the future. Models can be lesioned to test if change resembles behavioural deficits. Combing in methods can enable progressive from correlational observations to experimental approaches that provide causation