Crash Course Psychology #4

Crash Course Psychology #4 is introductory to the brain and how its localised parts are connected to the mind.

For context, Crash Course inspired me to learn the basics of psychology, so I’ve made it my mission to watch the entire Crash Course Psychology playlist and paraphrase each episode in my own words. This journey wouldn’t have been possible without the Crash Course team, so many thanks to them! To showcase what I learnt, here is my personal paraphrase of episode 4:

How it started with phrenology, a cult pseudoscience

It started in the early 1800’s by a German physician named Franz Joseph Gall, where he believed that a person’s personality was linked to their skull morphology. He would feel the bumps and ridges of one’s head to indicate aspects of their character. He’s the first known phrenologist. Phrenology is the detailed study of the shape and size of the cranium as a supposed indication of character and mental abilities. This became practice for decades and Gall became a celebrity, until phrenology became dismissed as a cult pseudoscience because those bumps and ridges on your head actually tell us nothing about the mind.

However, despite that, Gall led to an important discovery. His lasting and correct proposition was that different parts of the brain control specific aspects of our behaviour. In the previous episode, it was emphasised that everything biological is also psychological. Well, on top of the neurotransmitters and hormones, a lot of it is also because localised parts of the brain have specific functions. This is the link between the brain and the mind, which leads to the question: How do our brains’ functions tie to the behaviour of the mind?

Biology recap (Crash Course Psychology #4 & Crash Course Biology #26)

The Central Nervous System (CNS) is the command centre, which makes your bodies big decisions. If tampered, can cause problems. There’s also the Peripheral Nervous System (PNS), which has sensory neurons to collect data when activated by external stimuli, which is then reported back to the CNS. Both the CNS and PNS have sensor and motor neurons. This was only briefly talked about in this Psychology episode, and can be studied more comprehensively at The Nervous System – Crash Course Biology #26. Essentially, the CNS is responsible for analysing and interpreting all the data that your PNS collects and sends to the CNS. Once the CNS makes a decision based on the data provided by the PNS, it sends a signal back to the PNS to execute an order. This is done with motor neurons. These orders range from conscious muscle movement to the automatic functioning of organs.

This was a quick reminder of how biologically rooted our psychology is. To further grasp how physical the roots of our minds are, let’s look at the Phineas Gage case study.

The Phineas Gage case study

In 1848, a metal rod pierced through the left cheek and out the top of Phineas Gage’s head. This obviously caused brain damage, but it was focused to a specific region. Due to his survival and staying almost the same afterwards, he gained recognition. I say “almost” because apparently Phineas’s personality had changed after the incident. Accounts claimed that he was soft spoken prior, but became surly and vulgar after. Yet, all his other abilities remained the same. His memories were intact, could walk the same, etc. Phineas is a great, though extreme, example of how function is localised in the brain. How physical/biological factors can be reflected in psychological ways.

However, there is very little data on how Phineas was actually like before the accident to confirm his personality change. The same goes for after the event. Yes, the majority of accounts were after the incident, but they were not a lot in amount. They were also months after the event. Moreover, they conflicted. Which means it’s entirely possible Phineas’ personality had never changed after the incident. Phineas is also a great example of how individual case studies are not exemplarily useful.

Intro to psychology textbooks often paint the over simplified version of Phineas so that we get a clear picture that messing with the brain means messing with the mind. But it is of course, much more complicated than that. Since Phineas was a real person, he deserves the nuance as such.

Context of the brain

We may have heard that we only use 10% of our brain capacity, but that is actually a myth. Brain scans show that nearly every region of the brain lights up during even simple tasks like walking and talking. Not only that, but the brain itself requires 20% of all the body’s energy. So it would make little evolutionary sense to throw much energy away at something that’s only minimally active.

As animals, some of capabilities are thanks to our brain structures. Less complex animals have simpler brains to do basic functioning and survival such as rest, breathe, eat. More complex animals like many mammals have brains that can do that and more, like feel, remember, reason, and predict. These brains aren’t entirely new brains, they are new brain systems built upon old brain systems.

Those old brain systems, sometimes called the “old brain”, still performs for us now, even with the new brain systems around. As much as they did for our ancestors, too. Now we know how hard working our brains really are.

Brain Structure (Old Brain)

Here’s a look at our brain structures, starting with the “old brain”;

1. Brain Stem
   • The old brain is anchored here. This is the most ancient and central core of the brain. This is where the spinal cord enters the skull.
2. Medulla
   • Above the brain stem, at the base of the skull. Here, old brain functions happen automatically without any conscious effort. Things like your heart beating, lungs breathing, etc.
3. Pons
   • Perched on the Medulla. Helps coordinate movement. Also helps coordinate several other automatic functions. Has many other important jobs. To name a few are sleep, arousal, and relaying information between the cerebellum and the cerebral cortex.
4. Thalamus
   • Above the Pons, at the top of the brain stem. A pair of egg shaped structures that take in sensory information related to seeing, hearing, touching, and tasting.
5. Reticular Formation
   • Finger shaped nerve network inside the brainstem that’s essential for arousal. Not necessarily the sexual kind but refers to things like sleeping, walking, pain perception; other important functions.
6. Cerebellum
   • Baseball sized cerebellum, or “little brain”, positioned at the bottom of the brain stem. This is responsible for non-verbal learning, memory, perception of time, modulating emotions, and voluntary movement like dance. Also easily impaired by alcohol.

Basically the old brain systems keep our body’s basic functions running smoothly. This is the stuff any animal might need. However, this is where it stops for reptiles.

Brain Structure (The Limbic System)

For higher functions! As mentioned previously, used by more complex animals to do extra things like feel, remember, reason, and predict. We call this the Limbic System. We can interpret this as the border region between the “old brain” and the “new brain”.

1. Amygdala
   • Consists of two lima bean sized clusters of neurons. Responsible for memory consolidation and emotion such as fear and aggression.
2. Hypothalamus
   • Keeps your whole body steady. Maintains homeostasis. Regulates body temperatures, circadian rhythms, and hunger. Also helps govern the endocrine system, especially the pituitary gland. Also regulates your allowance for pleasure and reward, otherwise we may self induce over stimulation of them.
3. Pituitary Gland
   • Secretes many different hormones, some of which affect other glands.
4. Hippocampus
   • Central to learning and memory. If damaged, the person may lose their ability to retain new facts and memories.

Brain Structure (New Brain)

Above the old brain and the limbic system is this – the most advanced stuff.

Brain Hemispheres

The two hemispheres of your cerebrum make up about 85% of your brain weight, and oversee your ability to think, speak, and perceive. The left and right hemispheres govern and regulate different functions, giving us a split brain connected by a structure called the corpus callosum. For example, language is mostly controlled by the left hemisphere, while certain creative functions are controlled by the right hemisphere.

However, it is important to note that this does not hereby allow for the oversimplification that certain people have more dominant brains. Such as saying that a creative person is more right brain dominant, which is untrue. Yes, certain tasks are delegated to one side, but the two sides are deeply and constantly connected. We are not saying that they are completely unrelated, we are saying that you should always remember that the whole structure is an integrated system that works together at the same time.

Cerebral Cortex

Covering both hemispheres is the Cerebral Cortex. A thin layer of over 20 billion interconnected neurons. Also, this is heavily supported by your nervous system: the billions of non-neuron glial cells! This is a support that surround, insulate, and nourish the cerebral neurons.

The Cerebral Cortex’s left and right sides are subdivided into four lobes, all separated by especially prominent folds called fissures. Each lobe has it’s own functions;

1. Frontal Lobes (Just behind your forehead)
   • Speaking
   • Planning
   • Judging
   • Abstract thinking
   • Personality aspects
2. Parietal Lobes
   • Receive and process your sense of touch
   • Body position
3. Occipital Lobes (At the back of your head)
   • Receive information relating to sight
4. Temporal Lobes (Just above your ears)
   • Process sound, including speech comprehension

Each hemisphere controls the opposite side of the body, so the left temporal lobe processes sounds heard through the right ear, for example.

And within these lobes, there are still more regions that have specialised functions! The motor cortex which controls voluntary movements and the somatosensory cortex which processes incoming sensations are a couple of examples. There are also Association Areas that are related to higher mental functions like remembering, thinking, learning, and speaking. These deal with interpreting and integrating sensory input and linking it up with memories. This prevails in all four lobes so brain damage to different areas will cause very different results.

Conclusion of Crash Course Psychology #4

A lot of what happens inside of us biologically profoundly affects our mental experience. This is an important reminder of how fundamentally biology and psychology are intertwined.

Questions after Crash Course Psychology #4

1. After a bit of online research, it seems that the Cerebral Cortex is the most recent evolutionary development of the brain. It is located at the outermost layer of the brain. I wonder if this placement is because of how new it is? Therefore indicating that new brain matter grows on itself?
2. I researched about brain parts and their specific functions, and I kept finding conflicting information regarding which does what. Of course, besides the fact that anyone can post anything online and spread misinformation, I also suspect that it’s not as black and white. I think multiple brain parts work together to contribute to the same functions, which may explain the inconsistencies I find online. That’s my current best guess. At the time writing this post, I don’t have anyone to give me answers. So for now, I only have my early understandings to hang on to. My premature conclusion is that the multiple parts work together to contribute to those same functions, with varying degrees of work by each brain part for each function. This varying degree of work by multiple parts then leads to the labelling of primary functioning to one of those certain parts. But it’s all +/-.

Danniel’s thoughts on Crash Course Psychology #4

1. It would be real interesting to see a clear visual representation comparing and contrasting the differences between the Cerebrum, Cerebellum, and the Cerebral Cortex. It would really help psychology students who are primarily visual learners. Side track, I don’t believe in boxing students in to their (primary) learning styles. I believe we humans learn utilising all styles. I think educators should approach students utilising all the styles together for a more holistic learning experience. I’m just saying a visual aid like this would really help, of course on top of other things as well, at the same time.
2. This episode is covering a huge part of biology-psychology. It focuses on brain parts and their specific functions. Yet, this video is relatively short and only brings up a handful of examples. I acknowledge that I’ve barely skimmed the surface and I need to do more research and learning outside of this episode if I want to have a more solid foundation on this topic.

Enjoyed this learning of Psychology? Test your knowledge against these quick custom Kahoot! quizzes I’ve made based on the episode above: This is the easy mode and this is the hard mode for Crash Course Psychology #4.

Also, do check out what else Psychology related I’ve learnt from my Psychology blog!

Credits for Crash Course Psychology #4

Original Content & Media by Crash Course
Content Consumed and Paraphrased by Danniel Iskandar
Paraphrase Proofread by
Paraphrase Reviewed by