Module 9: 

• 1800s physician Franz Gall believed in phrenology, which is the study of bumps on the skull and how it can reveal one’s brain size and associated mental capabilities and character traits.

  • Was once popular, but is now discredited

• Phrenology, despite its flaws, brought attention to the localization of function, which is the idea that various brain regions have specific functions.

• Biological Psychologists study the links between biological processes (genetic, neural, hormonal) and psychological processes.

• Researchers studying the biology of the mind have revealed that:

  • Our adaptive brain is wired by our experiences.

  • Among the body’s cells are nerve cells that conduct electricity and “talk” to one another by sending chemical messages across a tiny gap that separates them.

  • Specific brain systems serve specific functions.

  • We integrate information processed in these different brain systems to construct our experience of sights, sounds, meanings, memories, pain, and passion.

• Humans can be identified as biopsychosocial systems, meaning we are composed of tiny biological systems and functions, which in turn affect our psychological processing and cognition, which in turn impacts our connection with the world and other people.

  • Biological; psychological; social

• Our body’s neural information system is built from neurons, which in turn impacts our emotions and perception of the world.

  • Neurons are nerve cells and the basic building blocks of the nervous system.

• Neurons are simple yet complex things, as they are made up of a cell body, dendrites, and axons.

  • Cell body: the part of the neuron that contains the nucleus, which is the cell’s life-support center.

  • Dendrites: the bushy, branching extensions of neurons that receive and integrate messages, conducting impulses toward the cell body. Receive messages from other cells.

  • Axon: the neuron extension that passes messages through its branches to other neurons or to muscles or glands. 

  • Neural impulse (action potential): electrical signal traveling down the axon.

  • Terminal branches of axon: from junction with other cells and is connected by a synaptic gap with another cell’s dendrites.

• Axons can be extremely short to very long (up to multiple feet long), and are encased in something called myelin sheath.

  • Myelin sheath: a fatty tissue layer segmentally encasing the axons of some neurons, enabling vastly greater transmission speed a neural impulses hop from one node to the next.

• Glial cells support billions of nerve cells.

  • Glial cells: cells in the nervous system that support, nourish, and protect neurons; they also play a role in learning, thinking, and memory.

• A neuron sends a message by firing an impulse called action potential.

  • Action potential: a neural impulse; a brief electrical charge that travels down an axon.

• Axons are selectively permeable, meaning that they only allow certain things through its gates.

• Resting potential can be defined as the positive-outside/negative inside state.

• When a neuron fires, the selective permeability changes of axons, as they completely open up, allowing positively charged sodium ions to flood in through the narrow channels.

  • The loss of inside/outside charge difference is called depolarization, allowing the next axon channels to open, and then next, and so on.

• If excitatory signals exceed inhibitory signals by a threshold, the combined signals trigger action potential.

  • Threshold: a minimum intensity; the level of stimulation required to trigger a neural impulse.

• A refractory period acts as a resting period or break for neurons.

  • A refractory period: in neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state.

• An all-or-none response can be defined as a neuron’s reaction of either firing (with full strength) or not firing.

  • A stronger stimulus can trigger more neurons to fire, and to fire more often.

• A synapse can be defined as the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron.

  • The tiny gap at this junction is called the synaptic gap or synaptic cleft.

• Neurotransmitters are chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

  • They excite or inhibit the adjacent, receiving neuron.

• A reuptake can be defined as excess neurotransmitters’ reabsorption by the sending neuron.

  • Sometimes these excess neurotransmitters can be broken down by enzymes instead.