Purves et al., (2018) EBOOK Key Reading (PP. 15; 21-29)

Question 1

what makes up the ‘somatic motor division’ of the PNS?

Answer 1

the motor axons that connect the brain and the spinal cord to skeletal muscles make up the ‘somatic motor division’ of the PSN

Question 2

What makes up the ‘Autonomic motor Division’ of the PSN

Answer 2

the cells and axons that innervate smooth muscle, cardiac muscle, and glads make up the autonomic motor division of the PNS

Question 3

what’s the most widely used method of functionally analysing the NS (4 points)

Answer 3

single cell, or single unit, electrophysiological recordings with micro-electrodes

often records several nearby cells - more info

• allows for cell-by-cell analysis of topographic maps and insight into which stimulus the neurone is ‘tuned’
• defines the neurones ‘receptive field’

Question 4

what can be done to assess receptive fields of neurones which aren’t concerned with space?

Answer 4

‘stimulus-selective responses’ (e.g. - the response to different odorant materials’

Question 5

what is the purpose of ‘cognitive neuroscience’

Answer 5

cognitive neuroscience is devoted to understanding perception, language, emotions, memory, and consciousness (more complex matters)

Question 6

state, and explain one approach to cognitive neuroscience

Answer 6

• to design and validate specific behavioural tasks that can be used to assess aspects of human or animal info processing and behaviour
• can be used to asses correct vs incorrect responses; number of trials to learn a task; reaction time between stimulus and response

Question 7

what is a use of neuroethology ? (2 points)

Answer 7

• when neuroethology is used with reductionist neuroscience methods, brain regions that are active when in tasks involving language, maths, music… can be evaluated
• carefully constructed behavioural tasks can also be used to study the pathology of complex neurological disorders that compromise cognition (such as Alzheimer’s)

Question 8

what were the two first phases of ‘brain imaging techniques’ ?

Answer 8

1) Pneumoencephalography

2) Cerebral Angiography

Question 9

state 3 points about ‘pneumoencephalography’

Answer 9

1) air injected into subarachnoid space which contains cerebral fluid (better x-ray contrast)
2) useful in visualising ventricular anomalies that cause hydrocephalus
3) risks & discomfort limits use to patients who’s provisional diagnosis could be proven this way

Question 10

state 5 points about ‘Cerebral Angiography’

Answer 10

1) a contrast agent is introduced into circulation via an arterial catheter
2) x-ray images taken from diff planes, revealing brain blood vessels
3) allows for identification of arterio-venous malformations
4) could diagnose strokes before other methods were developed
5) however, substantial risk of this method limits its use

Question 11

early functional mapping used Electroencephalography (EEG) –> explain what this is in 3 points

Answer 11

1) EEG relies on scalp electrodes to detect changes in electrical activity
2) careful focus when removing electrodes in individuals with epilepsy else it could trigger a seizure
3) Penfield & Jasper’s work lead to both ‘somatosensory maps of the body’ as well as ‘motor maps of movement intention expressed by the bodies musculature’

Question 12

what is good about ‘Event Related Potential’ (ERP)

Answer 12

ERP uses neither radioactivity or electrical stimulation

Question 13

explain what Event Related Potential (ERP) is

Answer 13

• net electrical activity from scalp electrodes detects, amplifies, and maps activity
• allows for general localisation during performance of different tasks by examining AP or ML EEG activity

Question 14

state a positive and negative of Event Related Potential (ERP)

Answer 14

• ease of use makes it possible to execute experiments in standard laboratory settings
• ERP lacks the ability to detect specific cortical areas

Question 15

what is ‘Transcranial Magnetic Stimulation’ (TMS) ?

Answer 15

TMS uses magnetic pulses delivered by a paddle-like devise held near the scalp

Question 16

explain what ‘Transcranial Magnetic Stimulation’ (TMS) is

Answer 16

• magnetic pulses delivered locally briefly disrupt underlying activity leading to transient changes in behaviour performance
• causes no harm to volunteers
• often used in combination with ERP analysis to assess typical activity patterns during complex motor behaviour
• when stronger magnetic pulses are delivered, it is possible to activate the output of the underlying cortical tissue

Question 17

what is ‘computerised tomography’ (CT)

Answer 17

CT is a non-invasive method of studying the living brain

uses a narrow x-ray beam and a row of very sensitive detectors placed on opposite sides of the head to probe a small bit of tissue at a time with limited radiation exposure

x-ray detectors rotate around the head collecting radio-sensitivity information from every orientation around a narrow slice

computer processing techniques the radio-sensitivity of each point creating an image

Question 18

state a pro and a drawback of ‘Computerised Tomography’ (CT)

Answer 18

• can readily distinguish grey & white matter, distinguish the ventricles quite well, and show many other brain structures with a spatial resolution of several millimeters
• its use in fundamental brain research on healthy individuals is limited due to the risks of unnecessary radiation exposure and its relatively low resolution of brain structure

Question 19

what is ‘Magnetic Resonance Imaging’ (MRI)

4 points

Answer 19

• the nuclei of some atoms act as spinning magnets
• if placed in wrong magnetic field. then atoms line up and spin at a frequency dependent on the field strength
• if a brief radio-frequency pulse is tuned to the atoms, the atoms are knocked out of alignment with the field and subsequently emit energy in an oscillatory fashion as they gradually re-align
• the strength of the emitted signal depends on how many atomic nuclei are effected by this process

Question 20

what are almost all radio-frequencies in MRI based off of?

Answer 20

tuned to spinning hydrogen nuclei in water molecules, creating images based on the distribution of water in different tissues

Question 21

state 3 benefits of Magnetic Resonance Imaging (MRI)

Answer 21

non-invasive (no dyes are injected)

safe (no high-energy radiation)

versatile (applicable to individuals with a range of conditions)

Question 22

what should you be considering when using Magnetic Resonance Imaging (MRI) ?

Answer 22

ferromagnetic objects in or near the scanner are a safety concern

Question 23

what are the two main results derived from Magnetic Resonance Imaging (MRI) ?

Answer 23

1) provides a suite of imaging modalities; by changing the scanning parameters, images based on a wide variety of different contrast mechanisms can be generated
2) can be used to detect changes in metabolic intermediates that may be related to ongoing neurotransmission

Question 24

explain how Magnetic Resonance Imagine (MRI) can be used to do the following:

can be used to detect changes in metabolic intermediates that may be related to ongoing neurotransmission

Answer 24

• takes advantage of the well-established capacity of magnetic resonance methods to detect diff organic molecules based on their atomic properties
• when used in human brain imaging, metabolites of excitatory amino acid neurotransmitters (e.g. - glutamate) or inhibitory transmitters (e.g. - y-amino-butyrate) can be detected, and their concentration and disruption mapped
• this approach can give us insight into the balance of inhibitory and excitatory modulators needed to perform complex tasks

Question 25

what is ‘Diffusion Tensor Imaging’ (DTI) ?

Answer 25

DTI is a variant of MRI using the alignment of the magnetic fields of water molecules in axon tracts which make it possible to visualise axon pathways

Question 26

what can Diffusion Tensor Imaging (DTI) do?

Answer 26

• DTI can establish differences in axon pathway connectivity, making it possible to study individuals with genetic disorders. that result in major alterations of axon projections

Question 27

what can Diffusion Tensor Imagine (DTI) additional settings also do?

Answer 27

• additional settings can generate images in which grey and white matter are relatively invisible, but the brain vasculature stands out in sharp detail
• thus, variations of MRI can clearly and safely visualise human neuroanatomy, including cerebral cortex regions, some subcortical structures, and axon tracts

Question 28

what is ‘Functional Brain Imagine’

Answer 28

functional brain imaging involves imaging specific functions in the brain that has become possible with the development of techniques for detecting local changes in cerebral metabolism or blood flow

to conserve energy, the brain fluctuates blood flow and metabolites

we can measure these changes and map them

Question 29

what are the 4 methods of Functional Brain Imaging?

Answer 29

Positron Emission Tomography (PET)

Single-Photon Emission Computerised Tomography (SPECT)

Functional Magnetic resonance Imaging (fMRI)

Magnetoencephalography (MEG)

Question 30

which Functional Brian Imaging techniques are less commonly used?

Answer 30

PET and SPECT are less commonly used for research of clinical use due to exposure to radio-labelled compounds

Question 31

what are the benefits of fMRI and MEG

Answer 31

fMRI: all the advantages of safety

MEG: excellent temporal resolution, allowing rapid acquisition of functional changes

Question 32

what is MEG limited by?

Answer 32

MEG is limited by it’s spatial resolution. this limits its utility in many situations (thus, fMRI is the most commonly used method)

Question 33

explain what Positron Emission Tomography (PET) is

Answer 33

unstable positron-emitting isotopes are incorporated into different reactants (e.g. - water, glucose) and injected into the blood

as isotopes decay, it emits two positrons travelling in opposite directions

gramma ray detectors placed around the head register a ‘hit’ only when two detections are simultaneously made 180 degrees apart

images of tissue isotope density can be generated , showing active regions with a spatial resolution of approx. 4 mm

depending on the probe injected, PET imaging can be used to visualise activity-dependent changes in blood flow, tissue metabolism, and biochemical activity

Question 34

what is SPECT ?

Answer 34

SPECT is similar to PET scanning in that it involves the injection or inhalation of radio-labelled compounds, which produce photons that are detected by a gamma camera moving rapidly around the head

Question 35

what are some basic benefits of fMRI?

Answer 35

fMRI is the least-invasive, most cost-effective approach for visualising brain function based on local metabolism

Question 36

explain fMRI

Answer 36

fMRI relies on HB distorting magnetic resonance properties of hydrogen nuclei in it’s vicinity. amount of magnetic distortion changes depending on whether HB is bound to hydrogen

when a brain area is activated by a specific task, it begins to use more O2, inc^ O2 rich blood to that area

this changes the conc^ of O2 and blood flow leading to ‘blood oxygenated level-dependant’ (BOLD) changes in the magnetic resonance signal

such fluctuations are detected using statistical image-processing techniques to produce maps of active brain regions

as fMRI uses signals and repeated observations can be made on the same individual, this is a major advantage over imaging methods such as PET

Question 37

what advantage does MEG have over fMRI

Answer 37

provides a way of localising brain function with better temporal resolution that fMRI. thus, MEG is sometimes used to map changes in brain function with millisecond resolution rather than the lower temporal resolutions of seconds afforded by fMRI

Question 38

what is MEG?

Answer 38

MEG records the magnetic consequences of brain electrical activity rather than the electrical signals themselves

MEG detects independent sources of current flow, without reference to other currents

the signals detected are quite local, and there is a fairly good spatial resolution (a few mm) of the signal origin

thus, one can detect dynamic electrical activity in the brain with a temporal resolution that approximates the key events in neural electrical signalling (i.e. - AP’s)

Question 39

how do you use a MEG?

Answer 39

AQUIDs (superconducting quantum interference devises) are arranged in a helmet and fitted onto the individual

the individual is placed in a biomagnetometer scanner that amplifies the signals detected by SQUIDs

these signals provide a map of the brain using reference points (usually nose and ears) to crease a 3D image

Question 40

state 2 uses of MEG

Answer 40

1) gives us millisecond (or even faster) temporal resolution combined with its spatial resolution, MEG can be used to evaluate local activity changes over time in individuals performing a variety of tasks
2) MEG can also map temporal characteristics, reducing the need for brain surface electrode mapping

Question 41

state and explain a common issue with the use of MEG

Answer 41

MEG mapping often lacks sufficient detail for some applications. thus, an be used to detect changes in metabolic intermediates that may be related to ongoing neurotransmission is often paired with structural MRI –> Magnetic Source Imaging (MSI)