Lab 2 - Answers PDF

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Neuroscience – Winter 202 1Lab #2: ElectroencephalographyLab reportName:KANYE WEST TA’s name: Sabrina Gallant ID#: CRN #:Record your data in the Table below and answer the questions. Your lab report is due to be submitted electronically by Sat, Feb 6, at 11:59pm. (50 marks total)Exercise 1 (10 marks...

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Neuroscience – Winter 2021 Lab #2: Electroencephalography Lab report Name:KANYE WEST ID#:

TA’s name: Sabrina Gallant CRN #:

Record your data in the Table below and answer the questions. Your lab report is due to be submitted electronically by Sat, Feb 6, at 11:59pm. (50 marks total)

Exercise 1 (10 marks): Common EEG Artifacts Describe what you are observing on the EEG recording when you are doing the following tasks in order to identify them as EEG artifacts (2 marks each):

Blinking During blinking, levels of both high amplitude & frequency were observed. On average, these high levels of amplitude & frequency lasted for 4-5 seconds, after which the levels returned to baseline levels. Alpha waves were more prevalent during blinking.

Rotating Head During head rotation, levels of high amplitude & frequency were observed, these levels were significantly higher than those observed during blinking. On average, these high levels of amplitude & frequency lasted for 7-8 seconds. Additionally, it was observed that frequency remained consistently high but the amplitude dropped almost periodically during the head rotation. Beta waves were more prevalent during head rotation.

Tilting Head Again, levels of both high amplitude & frequency were observed, both the amplitude & frequency levels were higher for head titling than they were for blinking and head rotation. On average, these high levels of amplitude & frequency were also more extend, lasting for 9-10 seconds. Beta waves were more prevalent during head tilting.

Based on the answers above for blinking and head rotate/tilt, what patterns would you expect to see on the Labscribe data file for the following movements?

Frowning I would expect to see amplitude & frequency levels that are lower than those observed for both head rotation & head tilting, but higher than those observed for blinking. Additionally, I would except these levels to last for 5-6 seconds & for alpha waves to be slightly more prevalent than beta waves.

Smiling I would expect to see amplitude & frequency levels that are lower than those observed for both head rotation & head tilting, but higher than those observed for blinking & frowning, as more sliming requires more muscle movement than both blinking & frowning. Additionally, I would except these levels to last for 6-7 seconds & for alpha waves to be noticeably more prevalent than beta waves.

Exercise 2 (10 marks): Alpha and Beta EEG Patterns Table 1: EEG Amplitude and Frequencies when subject has eyes open and closed (2 marks): Max-Min Amplitude (mV) !

Mean Frequency (Hz)

Eyes Open

CH

Eyes Closed

Eyes Open

CH

Eyes Closed

Left Beta Waves

!22.150

3

24.342!

-0.000!

4

!1.370

Right Alpha Waves

24.165!

5

28.733!

!4.431

6

5.147!

Right Beta Waves

14.209!

7

17.346!

!2.405

8

5.571

Left Alpha Waves

20.176!

1

!25.021

4.287

2

5.158

!

1. Do both hemispheres have a higher level of Alpha wave activity during the Eyes Closed or Eyes Open condition? Both hemispheres have a higher level of alpha wave activity during the Eyes Closed condition, as indicated by the significantly higher Max-Min values (Alpha) of the Eyes Closed condition.

2. Do both hemispheres have a higher level of Beta wave activity during the Eyes Closed or Eyes Open condition? Both hemispheres have a higher level of beta wave activity during the Eyes Open condition, as indicated by indicated by the significantly higher Max-Min values (Beta) of the Eyes Open condition.

3. Is the Alpha wave level of activity higher in one hemisphere than in the other during the Eyes Closed condition? Yes, the Alpha wave activity is higher in the right hemisphere than it is in the left hemisphere during the Eyes Closed condition. This is indicated by the higher Max-Min values (Alpha) values on the righthemisphere during the Eyes Closed condition.

4. Is the Beta wave level of activity higher in one hemisphere than in the other during the Eyes Open condition? Yes, the Beta wave activity is higher in the left hemisphere than it is in the right hemisphere during the Eyes Open condition. This is indicated by the higher Max-Min values (Beta) on the left-hemisphere during the Eyes Open condition.

5. Do these results demonstrate that the subject had an increased state of arousal when his or her eyes were open or closed? Give the reasoning (2 marks). Yes, these results demonstrate that the subject had an increased state of arousal when their eyes were closed. This is indicated by the higher Max-Min values values observed during the Eyes Closed conditions.

6. Do these results demonstrate one hemisphere had a higher state of arousal than the other? Give the reasoning (2 marks). Yes, the results demonstrate that the right-hemisphere exhibited higher states of arousal than the lefthemisphere. This is evident by the fact that in both the Eyes Open & Eyes Closed conditions, the righthemisphere exhibited higher Max-Min (generalized) values, which are indicative of a larger amplitude.

Exercise 3 (12 marks): The Alpha Block Table 2: EEG Amplitudes & Frequencies at rest and during problem solving (2 marks) Subject___________

CH

Resting

Problem1

Problem

Problem 2

Solved Max-Min Left Alpha Amplitude (mV)

3

21.74

Mean Left Alpha Frequency (Hz)

4

4.619

Max-Min Right Alpha Amplitude (mV)

7

Mean Right Alpha Frequency (Hz)

8

45.860

Problem Solved

27.537

39.912

27.600

0.245

0.023

0.026

5.069

11.243

22.580

12.296

29.654

16.242

3.309

0.029

0.092

0.029

0.615

Questions

1. Does either hemisphere have a lower level of Alpha wave during the problemsolving tasks than during the rest period? Yes, as both the left & right hemispheres have Alpha wave activities (Problem Solving) which are lower than the Alpha wave activities that were observed during the resting period.

2. Does either hemisphere have a higher level of Alpha wave activity during the periods after the problems are solved than during the problem-solving tasks? Yes, both hemispheres have higher levels of Alpha wave activity during the post-problem solving periods, as during these periods, the Max-Min (Alpha) values for both hemispheres were higher than they were during the resting period.

3. How do the levels of Alpha wave activity in the periods after the problems are completed, compare to the Alpha wave activity in the rest period? (2 marks) The levels of the Alpha wave activity in the post-problem solving periods is increasing, as the subject is no longer solving the problems, a period during which the alpha wave activity normally subsides & the beta wave activity increases. Additionally, the levels of the Alpha wave activity in the post-problem solving periods is higher than those found in the resting period, as the Max-Min (Alpha) values for postproblem solving periods were higher than they were for the resting period.

4. Can you identify a specific instance (as shown in the video) where movement has induced an artifact in the recording? Please identify one of these movements and describe where it occurs in the video (i.e. after asking the question, during or after answering, etc.)? (2 marks) When the subject is asked to “count backwards by 9”, the subject asks “Count backwards by 9?”, whilst asking this question, the subject’s facial muscles undergo movement. This movement of the subject’s facial muscles likely would have registered as an artifact in the beginning stages of EP2. During this period, significantly higher levels of Beta wave activity are observed.

5. Is the level of Alpha wave activity higher in one hemisphere than in the other during the rest period? During the problem-solving tasks? During the periods after the problems are completed? (3 marks) Yes, during the resting period, the level of Alpha wave activity was higher in the left-hemisphere than it was in the right-hemisphere. This was also true for the problem-solving tasks & the post-problem solving periods, during which the levels of Alpha wave activity were significantly higher than those fore the right-hemisphere.

6. Do your results demonstrate the presence of Alpha Block in the subject? Yes, the results demonstrated the presence of an Alpha Block. An Alpha Block can be identified when the Alpha wave pattern disappears and the Beta wave pattern appears, this will usually occur when the subject is performing a mental task or focusing. The Alpha block occurred in this experiment when the subject was asked to perform a series of arithmetics. Upon being presented with the problem & being told to solve the problem, the subject’s Alpha wave pattern decreased & was replaced by Beta wave patterns. After the problem had been solved, the subject’s Beta wave pattern disappeared & was replaced again by the Alpha wave patterns.

Exercise 4: Language and EEG patterns (18 marks) Read the article by Beres (2017) on language processing posted to Canvas in your lab folder. This article discusses the usefulness of time-specific EEG measurements in language processing, and the primary features of some of the more common indicators. Use the article to answer the following questions. 1.What is an ERP in language processing and why is it a useful way to measure cortical activity compared to non-time-limited measurements, such as looking at strictly alpha or beta waves? (2 marks)

An ERP (Even Related Potential) for language processing is one which reflects the modulation of brain activity by language comprehension & processing, in a precise moment in time. It is better suited to measure cortical activity, as unlike non-time-limited measurements, which consist of raw, continuous recording and thus make it very difficult to examine the specific neural activity as a function of certain cognitive processes, it is obtained by time-locking the stimuli. Doing so allows the researchers to know exactly at which point in time the stimuli was presented, this then enables them to analyze the brain response to the particular language-based stimulus. Additionally. ERPs in language processing are useful due to their good temporal resolution, which allows for reservers to assess the processing of a particular word.

2. Looking at the subtypes of ERPs, briefly define each one and describe why it occurs (i.e. what type of language process will elicit each signal)? (4 marks total)

a. The N400: The N400 is a subtype of ERPs and has a negative-going deflection that peaks around 400 milliseconds post-stimulus onset. The N400 is elicited when the target word is unrelated (semantically or categorically) to the proceeding word. Additionally, it is also found in auditory word association.

b. The P600: The P600 is a subtype of ERPs and has a positive wave of activity that occurs around 500-800 milliseconds. It can be elicited by syntactically incorrect or non-preferred sentences via visual (reading) experiments & by auditory (listening) experiments, such as violations in music.

c. Left Anterior Negativity (LAN): The LAN is a subtype of ERPs and has a negative-going deflection that peaks around 300-400 milliseconds post-stimulus onset. It is elicited by grammatical violations and garden path sentences, though less frequently.

d. Mismatch Negativity (MMN): The Mismatch Negativity component is a subtype of ERPs and has a negative-going deflection that peaks around 160-220 milliseconds post-stimulus onset. It is elicited in an auditory oddball paradigm, where a ‘standard’ sound is presented frequently & the ’deviant’ (differing in pitch, duration, & acoustic/phonetic properties) is presented in an arbitrary & infrequent manner. Additionally, it came also be elicited whilst subjects are listening to music, watching a movie, reading a book, sleeping or not engaging in a specific activity. 3. Why are ERPs used instead of simply looking at alpha and beta waves, as seen in today’s lab? What additional information do they provide? (1 mark)

ERPs are are useful due to their good temporal resolution, which allows for reservers to assess the processing of a particular word, this allows for the detection of fast-paced tasks (ex: language). 4. Though the article doesn’t devote a lot of time to alpha or beta waves, which type of wave is considered under the subheading “disadvantages”? What does that tell you about the type of brain wave (alpha or beta) that is more likely to be of interest in language processing studies? (2 marks) The Alpha wave is considered in the “Disadvantages” section. Since the Alpha waves are considered to be one of the aspects that researchers try to avoid, Beta waves, which are associated with a state of mental & intellectual activity and an overall state of alertness, are likely to be be of interest in language processing studies. 5. Which hemisphere, according to this paper, is more likely to be active in language processing studies? The left-hemisphere is more likely to active in language processing studies.

6. Putting all of this information together, theorize what might happen if you had your test subject hooked up to the EEG and they had to read aloud a sentence from a book. (4 marks total) a. What brain wave type and hemisphere would predominate?

The Beta waves & the left-hemisphere would be predominant.

b. Which ERPs would be most commonly seen in the EEG recording?

N400 & MMN ERPs

c. What if, during your experiment, the test subject made a mistake and mispronounced a word while reading aloud-which ERPs would be seen in that recording? (2 marks)

N400 & P400

7. Suppose you wanted to design an experiment to show the appearance of the P400. Very briefly, how could you design your experiment to elicit this ERP response? (2 marks)

In order to show the appearance of the N400, the subject would need to be presented with a stimulus which elicits the N400 (whilst being hooked up to an EEG), which as a component is elicited when the target word is unrelated (semantically or categorically) to the proceeding word. Thus, I would present the subject with the following phrase: ‘I take my coffee with cream and dog’ . Upon reciting this phrase, the EEG would measure the subject’s brain for electrical activity, this data can be filtered & averaged out util the a negative-going deflection of an N400 that peaks around 400 milliseconds poststimulus onset, can be detected.

8. Finally, though the Labscribe files you’ve looked at have not looked at language specifically, the Alpha Block file does feature attention switching from one task to another. Given this information, would you be likely to find the following ERP signals in the dataset? Briefly explain your answer. (2 marks total)

a. The N400: No, as N400 is more involved in is unrelated (semantically or categorically) errors.

b. The P600:

Yes, as it is involved in mathematics & sequencing (shown in the article)....