2.1 and 2.2 Lecture Notes

Chapter Two focuses on the physiological approach to psychology.
Examines the structural and functional aspects of the brain and nervous system in relation to behavior and mental processes.

Three main parts:
- General relationship between brain and behavior.
- Activity within the brain at the neuronal level.
- Overview of the brain's parts and the nervous and endocrine systems.
- Discussion of technology used to view and record brain activity.

Phineas Gage:
- A famous case in physiological psychology.
- Railway worker who suffered a severe brain injury yet continued functioning surprisingly well.
- Resulted in significant personality changes, emphasizing the relationship between brain areas and behavior.
Paul Broca's work:
- Conducted an autopsy on a patient who lost the ability to speak due to a stroke.
- Contributed to understanding the localization of brain functions related to specific behaviors.

Historical messages from Gage and Broca's findings stress the importance of studying specific brain areas for understanding human functions and behaviors.
Highlights the beginning of connections made between brain structures and their corresponding functions.

Types of Neurons:
- Sensory Neurons (Afferent Neurons):
- Carry sensory information from the body's sense organs to the brain.
- Motor Neurons (Efferent Neurons):
- Transfer commands from the brain to the muscles, facilitating movement and responses to sensory input.
- Interneurons:
- Act as connectors between sensory and motor neurons, allowing for communication among them.
Reflex Arc:
- Describes the instantaneous response to stimuli, such as touching a hot stove, facilitated by the rapid transfer of information via afferent and efferent neurons.

Neuron Components:
- Soma (Cell Body):
- The primary cell structure housing the nucleus.
- Dendrites:
- Branch-like structures that receive signals from other neurons.
- Axon:
- Long projection that transmits impulses away from the soma towards other neurons.
- Axon Terminals:
- Branches at the end of the axon that release neurotransmitters into the synapse.
Myelin Sheath:
- Fatty tissue covering the axon that increases the speed of electrical impulses.
- Impairment (e.g., in multiple sclerosis) can disrupt neuronal communication and function.

Electrical and Chemical Communication:
- Electrical impulses travel down the neuron's axon.
- At axon terminals, communication shifts to chemical signaling through neurotransmitters, which bridge the gap (synapse) to the next neuron's dendrites.
- Synapse:
- A small gap between the axon terminal and dendrite—critical for neurotransmitter action.
- Neurotransmitters:
- Chemical messengers that cross synapses, binding to specific receptor sites on the following neuron.
- Reuptake:
- Process by which unused neurotransmitters are reabsorbed by the sending neuron.

Agonists:
- Drugs that enhance the effects of neurotransmitters (e.g., increasing their action).
Antagonists:
- Drugs that inhibit or block neurotransmitter action (e.g., reducing their effects).
Impact on medications that adjust neurotransmitter levels affecting mood, movement, and other bodily functions.

Resting Potential:
- The state of a neuron at rest, with a low level of electrical charge when not firing.
Threshold and Action Potential:
- When stimulation reaches a threshold, the neuron exhibits an all-or-nothing response, firing an action potential.
- Action potentials represent brief, rapid bursts of electrical activity along the axon.
Refractory Period:
- The recovery phase post-action potential during which the neuron cannot fire again immediately.

Overview of the neuron’s electrical and chemical messaging systems sets up the foundation for understanding the brain's parts in the next section of the chapter.