The Biology of Behavior Lecture II

Biological Psychologists We study the links between our biology and behavior: Bottom-up approach. Last class: what is the most basic cell of the brain? From nerve cells to the brain.

Neuron Basics – Structure In order to understand how/why we think/behave, we should learn about how the cells that govern these items function.

Neurons Vocabulary Dendrite – bushy fibers attached to soma that receive information. Axon – pass messages through terminal branches. Myelin sheath – layer of fatty tissue that insulates axon and increases speed of information exchange (Muscular Sclerosis example). Terminal Branches – reach out and communicate with other neurons.

Neuron and Action Potential Information can travel as fast as 180mph, and, it does so in one direction: from the soma, across the axon, and through the axon terminals to other cells. Action Potential – the name of the impulse and sending of the information. It is activated through ionic exchange (electrochemistry). When a neuron is depolarized, we say it is achieving its action potential.

How Neurons Communicate

The Synapse

Neurons Use Neurotransmitters to Communicate Neurotransmitter – chemical messengers released from axon terminals to receiving neurons in the synapse. Reuptake – excess neurotransmitter is absorbed by sending neuron. (SSRIs)

Moving On: Nervous System The nervous system controls all information from the world and the bodies tissues. There are two sub-systems: (1) Central Nervous system (CNS) – decision maker (brain and spinal cord) (2) Peripheral Nervous system (PNS) – information gatherer and transmitter system (nerves, sensory receptors, muscles, glands)

Information Travel and Neurons Three Types of Neurons used in the Nervous System: (1) Sensory Neurons Carries info from body tissues and sensory receptors to the brain. (2) Motor Neurons Carry instructions from the CNS to body muscles. (3) Interneurons Information processing system of neurons. (in between).

Peripheral Nervous System Two components: (1) Somatic Nervous System enables voluntary control of skeletal muscles. (2) Autonomic Nervous System enables our glands and the muscles of our internal organs.

Autonomic Nervous System Has Two Functions: (1) Sympathetic Nervous System Arouses and expends energy. Heartbeat, breathing, etc. (2) Parasympathetic Nervous System Calms and reserves energy. Lowering blood sugar, etc.

Central Nervous System The brain enables our humanity, and, without it, we would not be able to: talk, think, feel, see, act. The brain is extremely complex. A system of neural networks. The Spine is our “Information Highway” Also governs our reflexes, pain response.

Before getting into the brain… The Endocrine System Secondary communication system. Uses hormones (gland secretions) behave like neurotransmitters. Think: Adrenaline, Growth Hormones, Sex Hormones.

The Brain

Brain as Complex We have a detailed blueprint of the brain as accomplished through brain mapping and testing. The brain is broken up into the regions and functionality. The brain has hierarchy – as the brain has evolved into the modern brain, it has built upon itself and has grown more sophisticate

The Brain Stem (and, Medulla) Begins where the spinal cord ends. Very basic functions – living and breathing. If a cat’s brainstem is severed from the upper brain, the cat will continue to live.

The Thalamus Rests near the spinal cord. A pair of egg-shaped structures. Receives all sensory information except for smell. It is the London to England’s train system. The central hub.

The Cerebellum Extends from the rear of the brainstem. Means “little brain”. Nonverbal learning, memory, judging time, modulates emotions. Relative to their body size, squirrels have HUGE cerebellums. Why do you think that is true?

The Limbic System Sets on top of the “old brain” and between the “old brain” and cerebral cortex. Hippocampus – conscious memories. Amygdala – aggression. Hypothalamus – homeostasis.

The Cerebral Cortex and Hemispheres Cerebral Cortex – outer covering of the brain made of interconnected neurons. “Thinking cap”

Psychology and the Brain Who is this handsome fellow?

Phineas Gage

Brain Stuff and Why it Matters Neural Plasticity – ability of the brain to modify itself after damage. Brain cells do not (normally) repair themselves after damage. Some brain regions are preassigned for functionality. Example: people who are blind have brain activation in the area where they “see” when reading braille.

Brain Stuff and Why it Matters Splitting the Brain The brain is connected via the corpus callosum – which connects the two main hemispheres of the brain. The brain is mirrored across the hemispheres, and if we literally split the brain, functionality is not lost.

Behavioral Genetics: The Biology of Behavior Because we share brain architecture: (1) We can begin to look at the environment (external influences) (2) We can begin to look at genetics (predisposition) Heredity versus Learned Use of Twin Studies, Adoptive Children, Biological Siblings… Why?

Gene-Environment Interactions Genes and experience interact. Genes are our beginnings, and experience colors the course. Again: Use of Twin Studies, Adoptive Children, Biological Siblings… Why?

Putting the Science to the Test Example 1: You are a behavioral counselor, and your client has suffered from a traumatic brain injury that resulted in damage to her limbic system. What may you assume of her current state? Example 2: The use of recreational drugs is associated with increased pleasure. What may you look for in a brain that you believe has been under the influence of a recreational drug? Example 3: John is a biological twin of Joe, and he presents as extremely hostile, aggressive, and uncontrollable. What measures may you want to take in order to develop insight for his condition?