The Brain
The brain has more cells than stars in the universe. Weighs at 3 pounds and looks like a walnut. More possible interconnections than atoms in the solar system. Divided into two halves called hemispheres. They communicate through the corpus callosum. For the test: you need to know the videos, the handouts, the notecards, up to chapter three in the book, etc., so don't wait until Wednesday night to start looking at the material. Tomorrow and Friday: playdoh.
Your brain is basically two fists together. Your brain is relative to your body's size. Does a bigger brain mean more smart? (Bryan says "yes"). The 10%-of-the-brain is a myth. If the outer coating of the brain, if it was flattened out, it'd be the size of a newspaper. The texture of your brain is like pudding. It has some chunks, mostly gooey. The best word for it is gelatinous- not quite firm jell-o. What holds it in its shape? A membrane- and once it's separated from the brain, it's just a mass. Each of those folds and curves indicates learning. The more wrinkled your brain, the smarter you are. The bumps up on your brain- those are called jiree and the dibs are called siree. The estimation is that there are more connections between neurons than there are stars in the universe.
Your brain is very fragile- it floats in water, it is easily bruised, and once damaged, it can't hardly recover. Brains are more complex than machines. We don't know as much as we need to. Your two hemispheres are joined by a band of axons- it's very thick and tight, called corpus callosum. The corpus callosum is a bridge so that the two halves of your brain can communicate, think about all of the coordination, and the halfs of the brain that control the halves of your body, and so you'd have two halves doing different things if this wasn't in place and it would be very strange.
Brain directions- ventral, lateral, midline, etc.
- Forebrain (uppermost & most largest)
- Cerebral cortex- divided into 2 hemispheres, sophisticated metnal functions, higher level thought
- Limbic system: learning, memory & emotional control. Your limbic system is kind of like your temples.
- Corpus callosum - band of axons connecting hemispheres
- Midbrain (middle region)
- Substantia Nigra- ("black stuff") motor control, dopamine. Coordination of your movements.
- Processes visual & auditory information; tracking. For example, if a book is dropped, you know where that sound is coming from- the brain analyzes the reverb, the sound and where it was originated, etc. A couple of years ago, Puckett had a surgery and was out for a few weeks, and Mrs. Horn was the substitute, and Horn was death, an so the psych class wanted to figure out which ear she was death in, so they gave a chart about Horn and hearing, and distance of sound, amount of time to react, the direction she turned, etc.
- Hindbrain (base & connects to spinal cord)
Runs most of the survival functions. That's what the hindbrain does.
- Pons: coordinate movements on right & left side of body; bridge. The pons coordinates information and movement, sends info back and forth from one side to another.
- Cerebellum: coordinates movement, balance & posture, motor skills, drunk. This is the round thing on the back of the brain that looks like another attached brain.
- Reticular formation or RAS (reticular activating system): regulate attention, alertness, sleep/coma. Sleep cycles too. That's why you can go into a coma or "deep sleep cycle" when you get hit in the back of the head.
- Medulla oblongata- breathing, heartbeat, & vital functions, primitive brain
- Midbrain + Hindbrain = Brainstem
Structures you must be able to label (half of them): emotion, behavior, awareness, memory, frontal lobe, somatosensory cortex, speech (Broca's area), hearing, smell, lateral fissure, temporal lobe, speech (Wernicke's area), vision, Balance and muscle coordination, occipital lobe, visual recognition, parietal lobe, motor cortex, central fissure, basic movements, skilled movements. You will not have to visually recognize these-- but it would be good ...
Brainstem
What makes up the brainstem? The midbrain and the hindbrain. On this image, they show you the cerebrum- cerebral cortex in other words, it's not in the brainstem. The brainstem is the cerebellum, the pons, the reticular activating system, the hypothalamus, etc. The cerebrum is the top half of the brain- the brainstem starts kind of "mid brain" at the thalamus. Hypo means under, so there's "hypothalamus" which is "the thing under the thalamus". Your thalamus is at the tip of the brain stim. The pituitary gland is not brain matter- but it is situated in the brain. The midbrain drops down to the pons, and then the medulla and reticular formation.
Limbic system
The forebrain!. This involves the hippocampus for memory, and then there's the thalamus which is a relay station for external stimuli, regulates attention motivation, awareness, and emtoional aspects of sensations. Thalamus and hypothalamus is in the midbrain, but they do have a role in the forebrain's limbic system. The limbic system is memory, learning, and emotions. It's just above your ears, around your temples. The hippocampus means "Ram's horn" and it's shaped kind of like that, it's curly, and its job is to do memory. Hippocampus helps store and process and retrieve memory.
The hypothalamus- detects changes in body system and corrects imbalance. The amgydala's job is to help process emotional memories, to help deal with intense emotions- fear, rage, etc. Here's how memory works: incoming stimulis that goes into the thalamus first, which then relays it into the parts of the brain that needs to process it (light, sound, etc.), and then that information is relayed back through the thalamus and goes back again. So if you have emotional connotations with the situation, the amgydala keeps in. If the party was a wonderful memory, you store that information, correlated with smells or something, and five years later you can smell the same smell and remember the same party, so emotional information gets paired into the amgydala and hippocampus all wrapped together. That's why your thalamus is considered part of the limbic system. The hypothalamus itself deals with all the things that you are doing to survive at the party: breathing, digesting, etc., it's the base or foundation, and then the relay (thalamus) and then it gets stored (hippocampus, thalamus, etc.).
Smell is the most active trigger of memory. You can smell farther than you can see. Smell first, then vision. Humans have horrible eyesight, in comparison to other animals.
PET scans - of women and men doing nothing. "Just hang out. Sit back. Chill." The University of Pennsylvannia found that on the PET scans- men had the limbic system going crazy, when they are just chilling. When women are chilling out, they string words together or something. "They say that women have a shifting-thought system based on language ..." Gender differences in thought-activity. Cingulate gyrus(shift attention from one thing to another).
The brain has two hemispheres- left & right sides are separate. Corpus callosum: major pathway between hemispheres. Hemispheric reaction in your brain. There are two separate parts with only one individual bridge- very tight set of axons. They have found that the hemispheres have separate jobs: the right hemisphere controls the left side of the body, the left hemisphere controls the right side of the body. There are some functions that are general, and they have found that the left side controls language and the right side does math and music. The latteralizatio of the brain is the division of jobs amongst the hemispheres. There's also contralaterialization- the fact that different sides of the brain control different sides of the body. That's why left-handed people tend to be more creative.
Lateralization is never 100%- that's a good thing. You still have redundant systems in your body and brain to help with coordination. What if the right side of the brain always controls the left side of the body/ Well, if you have brain damage, then you have this huge mistake evolutionary: you can't control the other side of your body. So there's some redundancy where you can control parts of your body across the pons. Once you split the corpus callosum, you have to totally relearn stuff.
Vision is the best way to explain how the lateralization works. The information from the eyes. You see with your left eye, which is controlled by the right side, so half of your retina in your left eye is controlled by the right side, the other side of the retina is controlled by the left side, so it's actually split down the middle ... that helps, because if you have a blow to the back of your head, you can still pick up the visual information across the other way. If you cut the corpus callosum, it does not effect vision, because the corpus callosum does not process vision.
Corpus callosum surgery- for severe epileptics. Epilepsy is like a thunderstorm in your brain: all of the neurons are firing at once, and there's no way to process all the information, and you go into seizures and shut down. So by cutting the corpus callosum you contain the storms, but you lose some functionality obviously.
Principle is Contralateral Organization- sensory data crosses over in pathways leading to the cortex.
Visual crossover- left visual field to right hemisphere.