Methods of Cognitive Neuroscience

Question 1

What is Gross Neuroanatomy?

Answer 1

It is one of the oldest methods that was used post-mortem (after death). The method is also know as dissection of the brain, where u do a autopsy of the brain by manual slicing it or dissection it in various ways.

Question 2

What dose gross neuroanatomy reveal?

Answer 2

Macroanatomy of the brain (main structures and connections)

Reveals large, conspicuous brain pathology.

Question 3

Vesalius and descartes used the gross neuroanatomy method? - True or false?

Answer 3

True, it was the only method available at the time.

Question 4

What is requiered to use in the fine neuroanatomy?

Answer 4

It requiers a microscope.

Question 5

A sample of tissue has to be prepared for microscopic viewing, what are some things that can be done to prepar a sample?

Answer 5

-Tracer stains: (to living tissue before sacrifice or sampling, to make
connections visible)
-Fixation: (to make sample more solid and easy to
-Staining methods: (to make single neurons
-Microtome: cutting extremely thin slices

Question 6

What are another way to explain “Cellular architecture of the cortex”

Answer 6

Brodmann areas

Side Note:
Brodmann’s areas of the cortex refer to 52 regions of the cerebral cortex that were identified in 1909 by German Neurologist, Korbinian Brodmann, based on cytoarchitectonic (cell size, spacing or packing density, and lamination) differences.

Question 7

Brodmann published his maps of cortical areas in humans, monkeys, and other species in 1909 - True or false?

Answer 7

True, Brodmann areas were originally defined and numbered by the German anatomist Korbinian Brodmann based on the cytoarchitectural organization of neurons he observed in the cerebral cortex using the Nissl method of cell staining.

Question 8

Describe what connectomics is?

Answer 8

Mapping of the “connectome, the “wiring diagram” of the brain.

Question 9

What is a singel-cell recording and what does it do?

Answer 9

It a traditional method in neurophysiology, used to monitor the spontaneous electrical activity of neurons.

Single-Cell Recording is a technique used in research to observe changes in voltage or current in a neuron. In this technique an animal, usually anesthetized, has a microelectrode inserted into its skull and into a neuron in the area of the brain that is of interest.

Question 10

Name the methods for Structural Brain Imaging?

Answer 10

• CT, CAT

- MRI

Question 11

Name the methods for Functional Brain Imaging?

Answer 11

• PET

- fMRI

Question 12

Name the methods for Electromagnetic Brain Sensing?

Answer 12

• EEG Electroencephalography

- MEG magnetoencephalography

Question 13

Name the methods for Electromagnetic Brain Stimulation?

Answer 13

• TMS, tACs, tDCs

- direct

Question 14

What does CT and CAT stand for and how does the method work?

Answer 14

A computerized tomography (CT) or computerized axial tomography (CAT) scan combines data from several X-rays to produce a detailed image of structures inside the body.

Question 15

What is a MRI?

Answer 15

Magnetic Resonance Imaging (MRI) is a method used for studying the functions of the brain (or any living tissue) without surgery. Images are obtained by using a strong magnetic field.

How it works:
MRIs employ powerful magnets which produce a strong magnetic field that forces protons in the body to align with that field. When a radiofrequency current is then pulsed through the patient, the protons are stimulated, and spin out of equilibrium, straining against the pull of the magnetic field. When the radiofrequency field is turned off, the MRI sensors are able to detect the energy released as the protons realign with the magnetic field.

Signal:
Frequency = Location
Intensity = Type of tissue

EXTRA:
This technology has improved medical diagnoses and research methods. For example, with a MRI, a psychologist can observe different structures in the brain by having a subject perform certain exercises or tasks.

Question 16

What do CT, CAT, MRI have in common?

Answer 16

Thay can only show the anatomical structures of the brain. Does not show brain activity of function.

Question 17

What is PET?

Answer 17

Positron emission tomography (PET), which is similar to the MRI, is a scanning method that enables psychologists and doctors to study the brain (or any other living tissue) without surgery. PET scans use radioactive glucose (instead of a strong magnetic field) to help study activity and locate structures in the body.

Question 18

What is fMRI?

Answer 18

A Functional Magnetic Resonance Imaging (fMRI) is a brain imaging technique that detects magnetic changes in the brain’s blood flow patterns. This technique is a combination of Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) scans and is useful for detecting changes in activation of different centers of the brain.This technique can be used to identify behavioral abnormalities that exist because of unusual activation of area of the brain.

Question 19

What do PET and fMRI have in common?

Answer 19

• Both can be used to detect brain activity (brain metabolism).
• Accurate in space, slow in time.

Question 20

What kind of signal arising from brain metabolism is detected in PET vs fMRI?

Answer 20

• PET: blood flow, energy consumption.

- fMRI: blood oxygen level.

Question 21

fMRI:What does BOLD stand for?

Answer 21

Blood oxygen level dependent.

Question 22

Explain the developed PET image?

Answer 22

The developed PET image resembles a “cloud of pixels/voxels” of different colors or different shades of gray where each color or shade represents a different degree of “activation” in the underlying brain structure.

Question 23

What does EEG and MEG have in common?

Answer 23

-Detect the electromagnetic
neural signaling of neurons

-Very fast in time, not very accurate in space.

Question 24

What is EEG?

Answer 24

An electroencephalogram (EEG) is a recording of the electrical waves of activity that occur in the brain, and across its surface. Electrodes are placed on different areas of a person’s scalp, filled with a conductive gel, and then plugged into a recording device. The brain waves are then attracted by the electrodes, travel to the recording device and then amplified so that they can be more easily seen and examined. The EEG recording can be used to examine a variety of brain functions including sleep (the different stages of sleep) and different psychological disorders.

Question 25

Who discovered the EEG and what else did he discover?

Answer 25

Hans Berger in search of “psychic energy”

-measured first cerebral blood flow, then electrical
potentials

-discovered robust alpha and beta EEG waves

Question 26

What is MEG?

Answer 26

Magnetoencephalography (MEG) is an advanced brain scanning technique which can measure brain activity millisecond by millisecond. It specifies the timing and location of neurons’ signals. MEG is helpful in studying and identifying perceptual and cognitive mechanisms and locating brain tissues prior to surgery. For instance, this technique has been used in knowing more about the unique neurological responses of patients with schizophrenia.

Question 27

Which frequencies can be seen in a EEG?

Answer 27

Divided into ”classical” frequency bands (i.e. how many ”waves” per second visible in the ongoing EEG) :

• delta < 4 Hz
• theta 4 8 Hz
• alpha 8 12 Hz
• beta 12 20 Hz
• gamma 20 70 Hz

Question 28

What is ERPs?

Answer 28

Event-related potential (ERP) is the measured brain response that is the direct result of a specific sensory, cognitive, or motor event. More formally, it is any stereotyped electrophysiological response to a stimulus.

ERPs are measured by means of electroencephalography (EEG).

Question 29

What is TMS?

Answer 29

Transmagnetic cranial stimulation (TMS) is a procedure that uses electromagnetism to stimulate nerve cells in the brain. It is a non-invasive technique which means no surgery or cutting occurs. A large metal coil that has electromagnetic components is placed on the scalp over particular regions of the brain. The electric currents stimulate neural connections in the brain and can help with multiple medical issues.

TMS can be used to help with major depression, sclerosis diseases, migraines, neuropathic pain, and schizophrenia. It can also be used to determine the extent of brain damage after a stroke. There are very rare side effects that can occur from TMS such as fainting and seizures.

Question 30

What is tDCS?

Answer 30

Transcranial Direct-Current Stimulation (tDCS) is a portable, wearable brain stimulation technique that delivers a low electric current to the scalp. A fixed current between 1 and 2 mA is typically applied1. tDCS works by applying a positive (anodal) or negative (cathodal) current via electrodes to an area. tDCS is a neuromodulation technique that produces immediate and lasting changes in brain function. The position of the anode and cathode electrodes on the head is used to set how current flows to specific brain regions. The current delivered by tDCS is NOT strong enough to trigger an action potential in a neuron; instead its “sub-threshold” changes the pattern of already activity neurons. Think of the brain as active, trying to do or learn something, and tDCS coming along to boost this ongoing activity. At the cellular level2, tDCS changes neuronal firing and by strengthening synaptic transmission between neurons by augmenting synaptic plasticity3 which is, in turn, the cellular basis of learning. tDCS is often combined with training. Training in itself produces learning (synaptic plasticity), and concurrent tDCS amplifies these effects (enhances synaptic plasticity). Some clinical applications tDCS is currently being explored for are depression, schizophrenia, aphasia, addiction4, epilepsy, chronic pain (migraine, fibromyalgia), attention, and motor rehabilitation. tDCS is also used for non-medical wellness applications, for example accelerated learning5, focus, relaxation, and meditation.6

Question 31

What is tACS?

Answer 31

Transcranial Alternating Current Stimulation (tACS) is a device that applies a low-intensity sinusoidal electrical current to the brain through electrodes on the scalp. The technique can be painless and is thought to boost the brain’s own oscillations, which can be used to treat disease or enhance brain function. In many ways tACS is similar to tDCS as a neuromodulatory technique, but instead of applying a direct electrical current, tACS oscillates a sinusoidal current at a chosen frequency to interact with the brain’s natural cortical oscillations. Generally, a large electrode is placed over an area of interest which applies stimulation while a reference electrode is placed in a neutral location. When a single, low frequency (< 100 Hz) frequency is applied the exogenous oscillation can synchronize with the brain’s endogenous frequency. This is typically what tACS is. When several oscillations are pulsated, desynchronization of cortical oscillations can occur. As such, tACS effects are contingent on the frequency, amplitude, and phase applied. tACS applied in the EEG frequency range (0.1-80Hz) can entrain neural oscillations, augmenting them. In higher ranges (1-5 kHz), oscillation interaction is unlikely to occur, but cortical excitability has been suggested1. tACS has recently become more popular with more clinical trials and even consumer devices, but it has a history that dates back decades2.

Question 32

What is true about image resoulution and brain reality?

Answer 32

in order to obtain an accurate image of the reality… The resolution of the instrument should be at the same level with the elements of the reality!

“seeing is believing” - if we see it we can believe it.

But dont get fooled: What do we really see when we look at the results or the colorful images?

No technique or method is yet good enough to see the bigger picture or the complete reality of the brain.

Question 33

What is said about temporal resolution

Answer 33

Temporal resolution refers to the accuracy of the scanner in relation of time: or how quickly the scanner can detect changes in brain activity

The method or the instrument itself may be slow : it generates or picks up signals at a slow rate (PET) -> low temporal resolution

The reality being imaged may be slow to react to changes in neural activity -> low temporal resolution AND questionable validity (fMRI)

Question 34

What is said about spatial resolution?

Answer 34

Spatial resolution is a term that refers to the number of pixels utilized in construction of a digital image. Images having higher spatial resolution are composed with a greater number of pixels than those of lower spatial resolution.