Structure and Operation of the Human Brain – Week 11

This week we only had an exercise session but no lecture or excursion. For the exercise session we went to Aalto Behavioral Lab and performed an EEG measurement with some students of the course being the subjects. Since the laboratory is quite small, the course was split in two groups that conducted the measurement after each other.

The task for the subjects was a variation of the reaction time test that was part of exercise 3. Luckily, we were supported by the staff of the ABL, so we only had to assist setting up the experiment. For me it was very interesting to see how an EEG measurement is performed because I had never seen it before. The subjects got on a cap with several electrodes and to get the right conductivity between the head and the electrodes, we had to put a gel between cap and head at each electrode. That was quite complicated as the cap didn’t touch the head everywhere and none of us had done something like that before.

After everything was ready, everyone apart from the subject head to leave the measuring room so that the measurement was not affected. The measurement only took a couple of minutes as the task for the subject was neither difficult nor long-lasting. Afterwards, we took a first look at the measured data which seemed to be good. I really liked that we did something practical in this last exercise session.

Posted by Franziska Schrank

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Structure and Operation of the Human Brain – Week 10

This week we had a lecture on brain connectivity, the wiring of the brain; in which was discussed that the connectivity is precise in for example the visual pathway and how the different cells are distributed and further differentiated to have different functions.

We also had our last excursion this week; we went to went to the Baba Center (BAby Brain Activity) in Helsinki Children’s Hospital, it’s a hospital but also a research center dedicated to studying babies’ brain activity.

Aside from providing healthcare as any hospital they have several research projects going on, such as AED, a project that investigates whether the antiepileptic medication during pregnancy affects the development of infant brain or later development of the child; RaMaVa, a project that studies the effect of maternal antidepressive medication on the development of newborn brain function; TOIBILAS, a pilot study designated to assess whether eyetracker-based cognitive tests could be used clinically to identify infants at risk of neurocognitive deficits; and VAURAS, a project which aims to understand the developmental effects of early-stage brain damage in babies.

 

image: www.babacenter.fi/en/

We were also shown some of the non-clinical research, a method of mapping the connectivity in the brain using MRI and a machine learning approach to monitor babies sleep (and make a hypnogram).

I really enjoyed these excursions as they provided insight not only into how the knowledge of this course is applied in the industry but also how it’s connected to other courses like Principles of Biomedical Imaging and what sort of things are being researched and developed.

Posted by Salvador Gutierrez Medina

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Structure and Operation of the Human Brain – Week 9

This week we had no lecture but instead two excursions. The first one took us to Aalto NeuroImaging (ANI). This is a research infrastructure at Aalto University, so we did not even have to leave the campus. ANI consists of three functional neuroimaging modalities, the navigated transcranial magnetic stimulation (nTMS) at Aalto TMS, the functional magnetic resonance imaging (fMRI) at Advanced Magnetic Imaging (AMI) Centre and the magnetoencephalography (MEG) at MEG Core. It was nice to get to see the different laboratories and the machines in them while hearing about what is done there.

The second excursion took us to Sooma, a company that develops and markets non-invasive brain stimulation devices for treatment of neurological and psychiatric disorders. There we got a brief introduction to the company’s history and then heard a lot about the research studies that had led to the development of their device and that have been done with their device. Afterwards, one of our group actually tested the device.

Multiple studies of depression show that there is a difference in neural activity in both brain’s hemispheres between patients with depression and healthy patients. So, what can be done with Sooma’s device is, that it can send an electric current through the human brain situating anode and cathode at specific areas on the skull, which aims at regulating the neuronal membrane potential between the brain’s hemispheres. Although the company was only founded in 2013 and they are still a small startup company based in Helsinki, the use of their device is spreading internationally, and research results of clinical trials indicate that the device can be a good replacement for drug therapy for some depression patients. The device can be seen in the picture.

Sooma tDCS

Image: http://soomamedical.com

I really liked the selection of excursions so far because we got to see a big internationally operating company but also a small startup company in the medical technology field and a non-profit research unit. Thus, I am really looking forward to next weeks excursion to Baba Center!

Posted by Franziska Schrank

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Structure and Operation of the Human Brain – Week 8

This week we had a lecture on the motor system; it started with a recap of the somatotopic map of the body surface onto primary somatosensory cortex, also known as the homunculus. It’s a visual representation which illustrates a cross section of the postcentral gyrus and represents which neurons are most responsive to parts of the body. This provided a good segue to start talking about the spinal control of movement.

To understand the somatic motor system (the skeletal muscle and the parts of the nervous system that controls them) we need to understand the motor units (a motor neuron and the skeletal muscle fibers that are innervated by the motor neuron’s axons) work- that is, to understand the muscles and the motor neuron’s innervations.

The muscle fibers only contract, and to cause extension or flexion of a joint we have different muscles which are extensors or flexors respectively. There are three types of motor units that contract: Fast fatigable, fast fatigue-resistant and slow, the type of motor unit is controlled by the type of alpha neuron.

We also reviewed the mechanism for this contraction at a molecular level.

In the last part we talked about the pathways from the brain to the muscles, which are how the brain controls the movements.

The function of the mirror neurons was also discussed.

I’m deeply interested in these topics especially in its applications, like the neural oscillators (model CPGs) that can be used for robot’s locomotion control so I’ve had already studied some of them before but it’s always good to go back to the basics and study such interesting topics again.

Posted by Salvador Gutierrez Medina

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Structure and Operation of the Human Brain – Week 7

This week, we talked about the human auditory system in the lecture. The human hearing capacity can lie between 20 Hz and 20 kHz and we are able to recognize very faint sounds but also very loud ones, so there is a large dynamic range. Sounds are a result of mechanical vibrations travelling to a medium like air or water through compression and rarefaction. If there is a load sound, small muscles attached to ossicles in our ear contract which protects the ear. Since there is a delay in the response of these muscles of about 50-100 ms, there can still be damage if the loud noise is sudden. Sounds are transformed into neural impulses through the basilar membrane and the hair cells. Where a sound is coming from, the brain calculates through the time difference between a sound reaching first one ear and then the other. At the end of the lecture we also talked about some basics of audiovisual integration in the brain.

We also had our first excursion this week which took us to Elekta, a company that produces equipment and software to help cure people with cancer or brain disorders. First, we heard about the company’s background, how it was founded and how it developed to an internationally operating company. Then we were introduced to the MEG and EEG machines they produce which are used in many countries of the world, how the machines developed over the years and what they are currently working on, which is a machine that combines MRI and MEG. We were also told that they try to invent better solutions of cancelling out the noise in MEG data coming from movement of the head during the measurement. This was a good transition to the last speaker, who is researching in this exact field to especially get better results for measurements of children’s heads since, depending on what age, you cannot tell them to keep their head still for a long measurement.

I really liked that we got an insight in what they are currently working on, but I would have also loved to actually see some machines and how they are build. Unfortunately, their machines are built in a different place, so this was not possible.

Posted by Franziska Schrank

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Structure and Operation of the Human Brain – Week 6

This week we started studying the visual system. Naturally the lecture started with a brief recap of the anatomy of the eyes themselves. Its parts and how we percieve the world, this is, how we see; how we transform the light into images.

We have two types of receptor which allow us to percieve the world, the cones and the rods. Furthermore, we have three types of cones, one which allows us to see the “Red” light, “Green” light and “Blue” light, depending on what wavelength are they more sensible to.

Something really interesting to ponder about is that we see colors thanks to these three types of cones, so how do other species see the world?-This question has led us to the discovery that dogs and other animals don’t see colors as well as we do, because they have fewer types of cones; however, what about the opposite?  Well, there are a number of animals who have more types of cones than us humans have. For example, butterflies, who have 5 types of cones, pretty impressive, but not as much as one particular animal, the mantis shrimp, who allegedly has more than 10 types of cones, one can only wonder how such a creature percieves the world.

Afterwards we started talking about the ways these receptors activate and we were presented with some pretty interesting optical illusions like how some people percieve colors differently even when they are the same just because of the difference in the environment and lightning.

One of the optical illusions presented in the lecture.

Finally we talked about the visual cortex and how the information from the eyes travels to the brain to be processed and in which processes are associated with different areas of the brain, overall it was a very interesting lecture and presenting us with related material to make us wonder about the topics presented makes the lecture’s flow better.

The lecturers also spoke about the difference in the hemispheress and how we are “two” people. Based on evidence of people with splitted-brain patients (the hemispheres being splitted was used as a treatment of epilepsy). I found a related video, which I’ll link below:

 

Posted by Salvador Gutierrez Medina

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Structure and Operation of the Human Brain – Week 5

This week the topic of last week was continued: Neurotransmitter systems.

I found good that the lecture was started with a revision of what had been done in the previous lecture. We then started with acethylcolinergic pathways as one of the diffuse brain systems. This pathway is thought to be linked to Alzheimer’s disease as the death of ACh cells was found together with early signs of the disease. Alzheimer’s disease is therefore characterized as a neurodegenerative disease and also as a form of dementia because it is linked to memory loss and cognitive impairment. To decelerate the progress of the disease the patients can take drugs which inhibit acethylcholinesterase to raise the acethylcholin levels in the brain. However, these drugs can neither cure the disease nor stop the progress completely.

ACh in the nucleus basalis of Meynert is also believed to play a role in learning progress by interpreting sensory stimuli.

Another diffuse brain system are the norepinephrine pathways. These pathways that ascend from the Locus Coeruleus widely innervate the brain as there are around twelve thousand neurons in the LC, each with around 250 thousand synapses. Each neuron can innervate both cortex and cerebellum. The NE pathways were found to react to salient environmental stimuli, leading to increased alertness, the enhancement of formation and retrieval of memory, and more focused attention, but they are also connected to mood, particularly to clinical depression, as norepineohrine increases restlessness and anxiety.

We went on to the dopamine pathways of the brain, the nigrostriatal pathway and the mesocortical and -limbic pathways. The dopamine pathways might be connected to Parkinson’s disease, as patients suffering from this disease were found to have low levels of dopamine in their basal ganglia. These low levels are a result of the death of dopamine neurons in the substantia nigra. There is no cure for the disease yet, but it is possible to improve movement related problems by giving the patients the drug L-Dopa which increases the dopamine levels in the basal ganglia.

The third diffuse brain system is the serotonin system. These pathways ascending from the Raphe nuclei in the brainstem innervate almost the whole brain. The serotonin system regulates wakefulness and arousal but was also found to play a role in mood. Together with the norepinephrine pathways it forms the reticular activation system of the brain.

After that we discussed the roles of hypothalamus and pituitary in controlling hormones and talked about the autonomic nervous system. The lecture was ended with an overall principle of neurotransmitter system functions, including that “everything influences everything” and that the change in the activity of one neurotransmitter system, for example through drugs, can widely influence other neurotransmitter systems, often in unpredictable ways, followed by a summary of what had been done in this lecture.

I really liked the references to current research status in some diseases and hope that the next weeks will include that as well and feature summaries of what has been done so far too.

Posted by Franziska Schrank

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Structure and Operation of the Human Brain – Week 4

This fourth week started, as usual, with a quiz. The quiz reviewed last week’s topics, the synaptic transmission. At the start of the course I was a little annoyed by having one type of examination each week; however I’ve come to like these quizzes, since they provide feedback as to how much you understood the previous topic and whether you should study more on some concepts so you don’t get left behind and can follow the following topics easily, since the topics build upon each other.

Things got a little fresh since we had some changes in the structure and approach to the lectures and exercise sessions. The lecture was prepared and given by Iiro instead of Risto like the last few lectures. The topic for this week was neurotransmitters and neurotransmitter system, things were a little bit more varied as we started with some background experiments between the link in alcoholism and opioid receptors and before going into the topic we also were presented with some videos to exemplify with some animations the ligand gated channels and the second messengers (cAMP).

Afterwards we boarded the lecture’s topic with some basic concepts, like what exactly is a neurotransmitter, their classification and what do they do; whether they are inhibitory or excitatory. We delved into each type of neurotransmitter and looked into the most prominent and common ones like Acethylcholine, GABA and glutamate, their receptors and what kind of reactions ensue when they’re recognized by said receptors; the principles of cholinergic synapses and the role of some neurotransmitters like GABA in the inhibition in the brain.

After this we returned to the second messengers cascades and then the relation between opioids and social bonding was discussed further.

Regarding the experiment session, although I wasn’t able to attend it I managed to do it later by running the program in my computer. We were presented with an experiment; to react to aural and visual stimuli and how different environments changed the reaction times.

I was pleasantly surprised to see some variety in how the lectures and exercises are presented and explained as this allows for a better understanding of them. I hope we can expect different approaches to the following topics.

Posted by Salvador Gutierrez Medina

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Structure and Operation of the Human Brain – Week 3

The third week started with a quiz again. One question of the quiz was about the cause of Alzheimer’s disease which is that the neurons fill up with neurofilaments and eventually die. As this had not been discussed in the lecture and wasn’t mentioned in the course book it was a tough question but also very interesting. In the exercise session, we discussed the different answering possibilities that were offered to the question and to which diseases they belonged, e.g. the degeneration of myelin sheaths in the central nervous system as a cause for multiple sclerosis. I hope that there will be more about diseases caused by defects in the neurons in one of the next lectures.

In the lecture, we first studied the different phases of the action potential and what happens in each of them with the concentration levels of potassium and sodium. This was terminated with a brief introduction to the patch-clamp-method which allows the study of single or multiple ion channels in a membrane. We went on to the different factors for the conduction velocity of the action potentials which are myelination and the thickness of the axon. The purpose of myelin-sheaths around the axons of neurons is mainly electrical insulation but it also decreases the capacitance in the axon so that it is easier for the action potential to travel. If the myelin-sheath isn’t intact anymore, signals that travel along the axon are slowed or stopped completely. Apart from the earlier mentioned multiple sclerosis there are several other diseases affecting the myelin-sheath, e.g. the Guillain-Barre syndrome.

Apart from characterizing neurons through their structure, for example pyramidical cells or stellate cells, which was discussed last week, neurons can also be classified by their behaviour in respect of the frequency of their action potentials. There are for example neurons with consistent action potentials that might have the function to transport a signal continuously over a certain time span while there are other neurons that only transmit a few action potentials at a high frequency which might be to transmit only the strength of a signal.

From there we went on to synapses between neurons. Synapses can exist between an axon and a dendrite, an axon and a soma or between two axons and one axon can also have multiple synapses. For chemical synapses, a neurotransmitter has to be synthesized, converted and stored in transporter proteins in the pre-synaptic neuron and then be released into the synaptic cleft, in response to an influx of calcium ions through voltage-gated calcium channels in the pre-synaptic membrane. I wonder, if this process could be interrupted in any way, for example using drugs and what consequences that would have.

Posted by Franziska Schrank

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Structure and Operation of the Brain – Week 2

After going through a general overview of both the course and the brain itself. This week we had the first quiz before the second lecture. Some of the gripes I’ve listened my classmates had was that it wasn’t really clear which topics would be covered for this quiz and that most questions only covered one part of the reading material. However, this week we got an announcement that clarified the topics that will be evaluated in next week’s quiz, showing us that the feedback has been heard.

In the lecture itself we covered some general topics from a biological standpoint, from neurons and glial cells, their types, classification, their organelles and their respective functions to the cellular membrane and finally we delved into proteins, amino acids, the ion channels and the Na/K pump. Even though the explanation dragged on for a bit, it’s understandable the detail of explanation that was given seeing as some people may not have previous knowledge about these topics if they don’t have a biological background and even for us who do, it was useful as well since we can remember things we may have forgotten.

In the exercise session we followed the topics in the first lecture, the brain itself and its different areas, with the twist that we dropped pen and paper and got our hands dirty!-so to speak. As we went with a hands-on approach and were tasked to build a model of the brain using modeling clay while we studied the different structures that make up the brain.

Even as a person who learns better just by reading I enjoyed the exercise session and I also understand that it may have been structured this way to aid people who learn better with visual cues.

I’m looking forward to the next lectures as we delve into the action potential and I wonder if we’ll go into detail with the Nernst equation and the Goldman-Hodgkin-Katz equation to end up studying the Hodgkin-Huxley model.

Posted by Salvador Gutierrez Medina

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