Cognitive Neuroscience Midterm 1

What is the definition of cognitive psychology?

The study of ‘mental activity’

In the 1950s, what were the three main influences on cognitive psychology?

World War II, AI, and Chomsky (linguistics)

What does cognitive neuroscience aim to understand?

The neural basis of cognitive function

Why was studying human anatomy prohibited prior to the renaissance period?

For religious reasons

How many years ago did Hippocrates contribute to the understanding of our mind and brain?

2500 years ago

Who is Andreas Vesalius and what were his contributions to the history of the mind and brain?

An anatomist who during the renaissance period, published the first anatomy book which included images of the brain

What does Rembrandt’s painting “The Anatomy Lesson of Dr. Tulp” illustrate?

An anatomy demonstration of the nerves of the forearm connecting to the spinal cord and brain, an increased interested in human anatomy

What is the story of Anne Greene?

Anne had a stillborn baby and was sentenced to death as a result, though she was found alive in the morgue and the physicians that ‘revived’ her using medical interventions became famous

Who is Thomas Willis?

One of the physicians from Greene’s story who wrote a famous brain anatomy book with the key terms of the cranial nerves and the circle of Willis (blood supply to and from the brain)

Who is Descartes?

A philosopher who originated the mind/body/brain philosophy (i.e., dualism)

What is dualism?

The philosophy that the mind is a non-physical entity separated from the body and brain

What is phrenology and where did it originate from?

The pseudoscience that one’s personality traits come from different bumps on the skull, it came from Gall and Spurzheim believing different parts of the cortex have different functions

What field of psychology did Darwin contribute to and how?

The field of comparative and evolutionary psychology: his book “The Expression of Emotions in Man and Animals” discussed the connection of emotions and biological origins and similarities in emotions between humans and animals

Who is Margaret Floy Washburn?

The first woman to earn a PHD in psychology, second woman to become APA president, research work on animal behaviour (paired association methods)

Who is referred to as the “founder of brain science”?

Ramon Y Cajal

How did Ramon Y Cajal contribute to the field of brain science (neuroscience)?

Demonstrated that neurons are individuals cells, not one continuous network by using the Golgi staining method and a light microscope to demonstrate his hypothesis = known as the neuron doctrine

What did Pierra-Paul Broca discover?

A region in the left hemisphere was tied to language production, specifically the “posterior part of the third front convolution” of the left hemisphere called Broca’s area

What did Carl Wernicke discover after Broca’s work?

The left posterior temporal region at the junction of the parietal lobe is known as “Wernicke’s area” = attached to speech perception and comprehension

Where is language primarily lateralized?

The left hemisphere for those right-handed, and 15% of those who are left-handed have it lateralized in the right hemisphere

Who is known as the ‘founder of psychology’?

William James: wrote ‘Principles of Psychology’ which is the first psychology textbook, showed Broca’s and Wernicke’s area based on evidence from brain damage

What do instruments of neuroscience primarily measured/record?

Electrical impulses and changes in blood flow

What was Helmholtz’s contribution to the field of psychology?

He conducted experiments involving electrical stimulation of frog legs to establish that nerve impulses travel along nerves.

What did Angelo Mosso discover?

The first neuroimaging technique by putting patients on a board upside down and recording changes in the brain’s blood pressure at the scalp = blood flow increases to the brain during mental activity

What is Angelo Mosso’s neuroimaging principle the basis for (in modern times)?

Techniques like fMRI and PET

What is a computerized axial tomography (CT)?

A 360 image made from x-rays of the brain created by injected dye into the blood vessels the lights up areas of inflammation/fluid

When was the first functioning CT scanner developed?

1972: the company EMI, record label of the Beatles, got so rich they invested in CTs

What does positron emission tomography (PET) scan measure?

Brain function by injecting radioactive isotope into an IV, it collects in areas of high cerebral blood flow or glucose metabolism, and emits energy as it decays for the PET to collect

Who developed the PET?

Michel Ter-Pogossian and Michael Phelps in the 1970s.

What is magnetic resonance imaging (MRI) critical for?

Neuroanatomy, such as soft tissue injuries, as it illuminates the difference between soft tissue and bone

Whose discoveries influenced nuclear resonance imaging (the principle underlying MRI)?

Isidor Rabi, Felix Bloch, and Edward Purcell.

When was the first theoretical model of an MRI developed?

1971 by Paul Lauterbur, which eventually became the first MRI scanner

Who developed the technique that eventually led to the fMRI?

Seiji Ogawa in 1990: technique that measures changes in the ratio of oxygenated to deoxygenated blood flow

What were Wilder Penfield’s contribution to the field of neuroscience?

Invented the Montreal Procedure (intracortical brain stimulation) to treat epilepsy

What did the invention Montreal Procedure led to?

The mapping of the sensory and motor cortices: homunculus

Who is Donald Hebb?

Psychologist, worked with Penfield, developed Hebb’s theory of learning (neurons that fire together, wire together)

Who is Brenda Milner?

Known as the ‘founder of cognitive neuroscience’, contributed to our understanding of language and memory (specifically hemispheric specialization of language) by working with patient H.M

What does an EEG/ERP measure?

The brains electrical activity

What kind of method is an EEG/ERP?

Temporally accurate: in terms of time, it has the highest resolution (measures as it is occuring)

What electrical activity does an EEG measure?

The summation of thousands of postsynaptic potentials (IPSPs and EPSPs)

Why is electrical activity primarily recorded at the scalp?

It is dominated by cortical pyramidal neurons (aligned in the same direction, allowing their activity to combine)

What are the three kinds of electrophysiological techniques?

Single-cell recordings (invasive, measures APs), EEG (non-invasive, measured summed EPSPs/IPSPs), and MEG.

What are the five kinds of EEG rhythms, from slowest to fastest?

Delta, Theta, Alpha, Beta, and Gamma

What are delta waves?

Slow waves associated with deep sleep, helps with memory consolidation and brain health

What are theta waves?

Waves associated with light sleep and drowsiness, plays a role in creativity, problem-solving, and retrieval.

What are alpha waves?

Waves associated with relaxed wakefulness, calmness, and eyes closed.

What are beta waves?

Occur when we are alert, associated with active thinking/concentration, helps with decision-making and focused mental effort.

What are gamma waves?

Associated with high-level cognition and intense cognition, plays a role in complex problem-solving and sensory integration.

What is magnetoencephalography (MEG)?

It measures the magnetic fields generated by electrical current within the brain sulci, using a helmet with sensors

Why does MEG have better spatial resolution than an EEG?

Its magnetic fields are not significantly distorted by the skull, cerebrospinal fluid (CSF), or surrounding tissues = like electrical currents are

What are the six main uses of a clinical EEG?

CNS integrity, auditory system integrity, sleep disorders, epilepsy, neurosurgical mapping, and neurofeedback

What is another term for cognitive evoked potentials?

Event-related brain potentials (ERPs)

What is an event-related brain potential (ERP)?

Neural activity that is related to an event, correlates to the mental processes during said event

How do we obtain ERPs?

They are derived from EEGs

What do the timing and amplitude of the peaks determine in ERPs?

The kind of cognitive processing is occuring (e.g., higher cognition occur later in time, visual processing occurs early)

On an EEG cap, what is the 10/20 system?

the standardized electrode placement used in research (universally used system)

What is an amplifier?

a device used to amplify the small EEG signals (typically by times 10,000) to be viewed

What is an electrooculogram (EOG) and what is it used for?

A device that records from near the eyes to reject data later if you are blinking or moving them

What is a “ground” i.e, a “ground electrode”?

A return path used to absorb any excess electrical voltage past what can be handled

EEG uses differential recording montages, what does that mean?

An EEG setup that measures the electrical difference between two electrodes: an active site on the scalp and a reference electrode (inactive site)

What is impedance and what should it be below?

Impedance refers to the resistance of electrical flow (due to oil/water), it should be below 10kohms to detect small differences

What is the difference between the reference and ground electrodes in EEG?

The reference provides a neutral site for comparison, while the ground electrode helps stabilize the recording by taking excess voltage

What are common spots for the ground electrode to be placed?

The cap site or arms

What are common spots for the reference electrode?

Nose tip and ears

What is the rule of thumb for the EEG sampling rate?

How often you want to sample EEG data is 2x the highest frequency you are recording (e.g., highest frequency is 100 Hz, the sampling rate should be 200 Hz)

What is the difference between low-pass and high-pass filters in EEG?

The low pass allows frequencies below a certain hz through, while the high pass allows frequencies above a certain hz through

What is a notch filter in EEG?

Removes frequencies, ‘background noise’, associated with nearby electrical equipement

In terms of the sampling rate, how do you calculate when a data point is collected (i.e., 1 data point every __ ms)?

There are 1000 milliseconds in 1 second, so take 1000/(sampling rate)

What is signal-to-noise ratio (SNR) in EEG/ERP recordings?

The ratio of ERP signal to the unwanted background EEG noise, e.g., higher SNR = ERP signal is easier to identify

What is segmenting (epoching/windowing) in ERP?

Extracting parts of the EEG data, typically from 100 ms before to 1000 ms after the stimulus

What is filtering in an ERP?

Done after segmenting, the narrowing of the frequency range (bandpass) to reduce unwanted frequencies

What are artifacts and why do we remove them?

Artifacts are unwanted eletrical activity due to eyeblinks and eye/body movement: since artifacts are very large, rejecting trials of ±75 microvolts removes them

What is signal averaging?

Used in ERP, the averaging of multiple trials at each electrode location for a single condition to remove background noise

What is baseline correction?

Average the activity occurring during the prestimulus period (-100 to 0 ms) = around zero, establishes a baseline for all conditions

What is N400 ERP component associated with?

Semantic processing: peaks 400 milliseconds after stimulus, negative going

Where is the N400 typically largest in amplitude, spatial wise?

Over the right centroparietal (parietal/center) region

How are the hemispheres and midline identified in the EEG 10/20 system?

Left hemisphere contains odd numbers, right hemisphere contains even number, ‘Z’ is the midline

What do the letters in the EEG 10/20 system represent?

A = ear lobe, C = central, Pg = nasopharyngeal, P = parietal, F = front, Fp = frontal polar, O = occipital

What is the total amount of electrode channels that can be placed on an EEG cap?

256 channels

What does the spatial distribution of an ERP represent?

Where the ERP responses is strongest, but it does not mean it is necessarily generated there

What is the reason that ERP doesn't reveal where the activity originated from?

Multiple neural sources contribute to the signal, the skull/meninges distort the activity before it reaches the scalp, and the orientation of the source influences it

What is dipole modelling in EEG/ERP?

A procedure used to estimate the location of the neural sources using more channels to better the estimation

What are the main 5 advantages of ERP?

No overt attention needed, good time-resolution, non-invasive, non-behaviour focused, and can be used on infants and clinical populations

What is the main disadvantage of ERPs?

Poor spatial resolution

What is the hemodynamic response as measured by fMRI and PET?

A localized change in blood flow, associated with neural activity and increased oxygen metabolism (consumption)

As neural activity increases, what happens to blood flow?

Increased neural activity → increased oxygen consumption → increased oxygenated blood flow to the active region to ‘replenish’ oxygen

What does positron emission tomography (PET) measure?

The ‘local cerebral blood flow’ (blood flow to areas of high metabolic activity)

How does a PET scan work (the process)?

A radioactive tracer is injected into the bloodstream, which concentrates in high activity tissue

What organ(s) are frequently targetted with PET?

The liver and other hard-to-view organs

How does PET produce a detectable signal?

The radioactive tracer molecules turns unstable and decays during which it emits positrons, when those positrons travel and run into electrons they begin annihilation, which emits 2 photons which are detected by the scanner

What kind of spatial resolution does PET have?

Moderate: 2-3mm error for one individual, and 10mm across multiple individuals

What is the temporal resolution of PET?

Poor: 30-45 sec after activity, though tracer must be injected for an hour to be absorbed as well

What is the primary difference between MRI and fMRI?

MRI is brain anatomy, while fMRI is brain function

What is the main magnetic field of an MRI scanner?

B₀, which is continuously on and only attracts pure metallic items

How is the strength of an MRI magnetic field measured?

According to Telsa, where 1 Telsa = 10,000 Gauss

How much stronger is a 4T MRI machine compared to the Earth’s magnetic field?

80,000x stronger (Earth’s field is less than 1 Telsa at 0.5 Gauss, while a standard MRI is 4 Telsa)

Why are participants required to wear earplugs during an MRI?

It produce extremely loud noises (up to 120 dB)

What physics principle does MRI use to produce images?

Nuclear Magnetic Resonance (NMR) using Hydrogen (H) protons

Why do MRI machines specifically measure hydrogen protons?

They are abundant in the human body and have nuclei with an odd number of protons (1), so it has non-zero nuclear spin that acts as a magnet

Why can nuclei with an odd number of protons be measured, using NMR principles?

If the number of protons is odd, they cannot cancel each other out with their spin

What happens to hydrogen protons outside an applied magnetic field (without MRI)?

They are randomly oriented, causing their magnetic effects to cancel out and resulting in zero net magnetization (M = 0).