(Module 1) The Brain and Behavior

Introductory:

Behavioral Neuroscience (Biological Study) - The study of the brain’s role in behavior.

The brain is a massive network composed of billions of brain cells wired together to pass information back and fourth. It is a complex triad of architectural (brain structure), electrical (action potential), and chemical (neurochemicals) working together.

As parts of the brain are labeled and processes within the brain are defined, emergence is always at play.

→ emergence occurs when the whole is greater than the sum of its parts. Meaning the whole has properties its parts do not have.

Architecture

Hindbrain: Controls the most basic functions of life

Medulla: (adjoins the spinal cord) controls breathing, heart rate, blood circulation, and balance.

Pons: (Above the Medulla) controls attentiveness, timing of sleep, and dreaming. Damage to certain parts of the pons can put a person into a semi permanent state of sleep. REM sleep may also originate in the pons.

Reticular Formation (Inside the Medulla and Pons): Network of nerves extending from the spinal cord through the thalamus. Plays a role in autonomic functions of the body like circulation, respiration, and digestion as well as pain modulation, sleep, and consciousness.

Midbrain: (Sitting on top of the Pons): Helps orient an organism in the environment and guide movement toward or away from stimuli. Believed to regulate our experience of pain, modulate mood, and shape motivation.

Cerebellum (Behind the pons and medulla): coordinates voluntary movements like posture, balance, and coordination. Damage can cause problems in spatial reasoning, discrimination sounds, and integrating input from various sensory systems. May also help us judge time, modulate our emotions, and discriminate sounds/textures.

Forebrain:

Thalamus: Involved in sleep, wakefulness, and relaying motor/sensory signals to the cortex. Closes pathways of incoming sensations during sleep

Hypothalamus (under the thalamus): involved in motivated behavior like eating, drinking, and freaky time activities. Also involuntary rhythms like the sleep/wake cycle and detecting when the body is too cold or too hot.

Amygdala: Play a role in emotional response, anger specifically, and is involved in determining if a stimulus is a threat or not. Helps predict when something frightening is going to happen (like in video games or seeing uncanny valley faces)

Hippocampus: Plays a role in learning, memory, spatial orientation, and creating new memories.

Cerebral Cortex: involved in every thought and perception, as well as our ability to produce and understand language and to construct and experience emotion. Crucial in order to believe, organize, remember, and hope. The cortex is a thin outer surface covering the brain (three millimeters thick on average). Makes up 80% of the brain, crumpled up sheet of tissue.

Deepest groove in the brain is the longitudinal fissure, which divides the brain into the right cerebral hemispheres and left cerebral hemispheres. The right and left are connected through the Corpus collosum (a thick band of fibers), which allows for communication between the two hemispheres of the brain. Responsible for transmitting neural messages.

Right Hemisphere: Controls muscles on the left

Left Hemisphere: Controls muscles on the right

Sensory information from the left side crosses the corpus callosum to the right hemisphere while information from the right side crosses to the left. Damage to one side of the brain will damage the opposite side of the body.

Parts of the Brain:

Frontal lobes, Central fissure, Lateral fissure, Parietal lobes, Temporal lobes, and Occipital lobes

Three broad types of cortical tissue:

Sensory Areas: Receive and Interpret information from eyes, ears, etc..

Motor Areas: Control our behaviors

Association areas: Connects sensory and motor areas, involved in many complex processes (Thinking)

Stimulation in the Primary Motor Cortex (located in the back of the front lobe) leads to movement of specific body parts.

Each portion of the primary motor cortex corresponds to a specific part of the body. Demonstrated by Motor Homunculus (cursed image that should NOT exist omfg)

The parts we can move with the greatest precision (fingers, tongue) receive more cortical area than those we have less control over (shoulders, abdomen)

Primary Somatosensory Cortex (located directly behind primary motor cortex): Initial receiving area for sensory information arriving from the skin sense. Space is proportional to sensitivity. Brain has similar areas for sight and hearing.

Prefrontal Cortex: involved in planning, decision making, mood, personality, and self awareness.

Complex processes are a result of synchronized activity.

Electrical Activity

There are 10 to 15 times more neurons than people on earth. (Not important, just a fun fact lol)

Neurons include…

Dendrites (Input side of the neuron. Receives signals from many other neurons.

Cell body (Contains nucleus and elements need for metabolic activities)

Axon: Output side, sends signals.

Glia: Broad set of functions: provide nourishment, control nutrient supply (convert Glucose → Lactaid), provide oxygen and fuel. Involved in the brain’s development. Ensures stable patterns, or send signals to strengthen connections/activity. Increase speed of neural communication.

Action Potential:

Neurons main response to input and fundamental information carrier of the nervous system.

Key words: Repolarization, Ions, Potassium, Myelin Sheath, Nodes of Ranvier

120 METERS PER SECOND 🤯😱😱😱🤯

Chemical Messages

When the Action Potential reaches the axon terminal it release neurotransmitters into the synaptic cleft.

What happens to neurotransmitters after affecting the postsynaptic neuron?

-Special cleanup enzymes, reused and repackaged (Synaptic reuptake)

Excitatory Neurotransmitters:

Have excitatory effects on neuron and increase the likelihood the neuron will fire an action potential

-Acetylcholine

-Glutamate

-Noradrenaline

-Histamine

-Increase fight or flight neurotransmitters (Epinephrine, Norepinephrine)

Inhibitory Neurotransmitters:

Have Inhibitory effects on neurons and decrease the likelihood the neuron will fire an action potential.

-Serotonin

-GABA

Acetylcholine and Dopamine can be Inhibitory or Excitatory depending on the type of receptors that are present.

Glutamate (Rapidly excites, enhanced memory and learning. Excess doses result could lead to Schizophrenia due to overstimulation) and GABA (Inhibits, critical roles in learning, memory, and sleep. absolute workhorse 🔥) are the most common neurotransmitters in the CNS.

Medication:

Chemicals that enhance a transmitters activity are called Agonists (Mimic, block, and counteracting clean-up enzymes) while those that diminish are called Antagonist (Binding/Putty/Block, Speeding reuptake, Augmenting clean-up enzymes).

Individual Neuron Selectivity.

Key elements in flow of information:

-Selective receptor response

-Different neurotransmitters provide different signals

Degeneracy: Many to one (Many combinations of neurons can produce the same outcome.)

Core Systems: One to many (A single core can play a key part in many things like hearing, thinking, seeing, etc..)

Right or Left Brain

Right half of your brain processes creative tasks, left half handles math or form language

Roger Wolcott Sperry and Micheal Gazzaniga created the idea of left and right hemispheres of the brain (and led to the overexaggerated and watered down idea in popculture)

Language and Calculation- Left brain

Spatial reasoning- Right brain

Logic on the Left, creativity on the right

Some people could have opposite left and right brains compared to the majority

Brain Lateralization: certain functions or processes are specialized to one side of the brain.