FINAL+REVIEW+Spring+2026

Conceptual Hierarchy: Understanding behavior requires an integration of multiple levels of analysis, ranging from social interactions to molecular events.
Social Level: Focuses on individuals behaving within social interactions.
Organ Level: Examines major anatomical components including the brain, spinal cord, peripheral nerves, and eyes.
Neural Systems Level: Analyzes specific systems such as the eyes and visual brain regions working in concert.
Brain Region Level: Focuses on specific cortical areas, such as the visual cortex.
Circuit Level: Investigates local neural circuits and the flow of input and output signals.
Cellular Level: Examines the single neuron as the functional unit of the nervous system.
Synaptic Level: Studies the junction between neurons where communication occurs.
Molecular Level: Investigates membrane receptors and intracellular signaling pathways.

Hebbian Theory: A fundamental principle in neuroscience suggesting that "cells that fire together, wire together."
Basal State: The initial, standard firing rate and synaptic strength between neurons.
Hebbian Plasticity: The process by which synaptic connections are modified based on activity.
Long-Term Potentiation (LTP): * Characterized by the strengthening of active synapses. * Results in an increased firing rate compared to the basal state. * Crucial for memory formation and learning.

Pathway Function: Regulates reward, motivation, and reinforcement.
Dopamine Release: Triggered by various stimuli, including substances like coffee.
Functional Components Involved: * Reasoning: Higher-level cognitive processing of rewards. * Emotion: The affective response to rewarding stimuli. * Memory: Storing information about rewarding experiences for future behavior. * Motivation: The drive to seek out rewarding stimuli.

Endogenous Ligand: Naturally occurring substances (like neurotransmitters) that bind to and activate receptors.
Agonists: * Molecules that bind to receptors and activate them. * Function similarly to the endogenous ligand to produce a biological response.
Antagonists: * Molecules that bind to receptors but reduce or block receptor activity. * Prevent the endogenous ligand from binding and activating the receptor.
Pharmacodynamics: The study of the biochemical and physiological effects of drugs on the body and the mechanisms of drug action.

Brainstem (Midbrain, Pons, Medulla): Serves as the primary connection point between the spinal cord and the brain. * Midbrain: Responsible for receiving and processing visual and auditory information; also regulates muscle movement. * Pons: Controls the sleep/wake cycle, facilitates motor control, and acts as a bridge for body-brain crosstalk. * Medulla: The final connection point for the brain and spinal cord; acts as a critical controller for autonomic body functions and body-brain crosstalk.
Thalamus: Primarily functions as the relay center for sensory and motor signals, directing them to the appropriate cortical regions.
Hypothalamus: Receives sensory input and is the main regulator of homeostasis in the body.

Limbic System Composition: Includes the amygdala, hippocampus, hypothalamus, thalamus, nucleus accumbens, and cingulate gyrus.
General Functions: Important for learning, memory, cognitive functions, emotional regulation, and processing senses.
Specific Structures: * Amygdala: Specialized for emotional memory and processing, specifically fear and anxiety. * Hippocampus: The main region for memory consolidation and spatial navigation. * Nucleus Accumbens: Processes reward and reinforcement; involved in cognitive motor functions. * Cingulate Gyrus: Acts as a regulator of emotions, pain, and fear.

The Neuron: Comprised of major parts including dendrites, cell body (soma), and axon.
Dendritic Spines: * Small protrusions found along the length of dendrites. * Serve as a key location for neuronal input. * Highly dynamic structures essential for neuronal plasticity.

Ionotropic Receptors (Ligand-Gated Ion Channels): * Activated directly by neurotransmitters. * The receptor itself contains an ion channel that opens upon binding. * Immediately affects the postsynaptic cell's membrane potential by allowing ions (like $Na^+$ or $K^+$ ) to flow.
Metabotropic Receptors (G Protein-Coupled Receptors): * Activated by neurotransmitters but do not contain an integral ion channel. * Activation triggers G proteins. * G proteins may subsequently open other ion channels or cause intracellular biochemical changes through second messenger cascades.

Extracellular vs. Intracellular Environments: Characterized by differing concentrations of ions.
$Na^+ / K^+$ Pump: Maintains the resting membrane potential by actively transporting ions against their gradients.
$K^+$ Pores: Specific channels that allow the leakage of potassium ions.
Voltage-Sensitive $Na^+$ Channels: Crucial for the generation and propagation of action potentials; they open in response to changes in membrane voltage.

History of Antidepressants (1957): * Iproniazid: The first Monoamine Oxidase Inhibitor (MAOI). * Imipramine: The first Tricyclic Antidepressant (TCA).
MAOIs (Monoamine Oxidase Inhibitors): * Inhibit the enzyme monoamine oxidase, preventing the breakdown of monoamines like dopamine, serotonin, and norepinephrine in the presynaptic terminal.
Tricyclics (TCAs): * Inhibit the reuptake of dopamine, serotonin, and norepinephrine from the synaptic cleft.
SSRIs and SNRIs: * SSRI: Selective Serotonin Reuptake Inhibitor. * SNRI: Serotonin-Norepinephrine Reuptake Inhibitor. * Distinction: These are "SELECTIVE" reuptake inhibitors, targeting specific monoamines more precisely than typical tricyclics.
Lithium Salts: * Used primarily to combat bipolar disorders. * Mechanism involves $Li^+$ acting in place of other cations, influencing dopamine activity, and modulating GABA activity.

Potentials: Excitatory (EPSP) or Inhibitory (IPSP) postsynaptic potentials spread passively over dendrites and the cell body to the axon hillock.
Transmitter Release: Vesicles release neurotransmitters into the synaptic cleft.
Breakdown and Reuptake: * Enzymes in the extracellular space break down excess transmitter. * Reuptake transporters recycle the transmitter back into the presynaptic neuron to slow synaptic action.
Autoreceptors: Neurotransmitters may bind to autoreceptors on the presynaptic membrane to regulate further release.

Amygdala Circuit for Anxiety: * Inputs: Receives signals from the sensory cortex, prefrontal cortex, and thalamus. * Key Regions: Lateral Amygdala (LA), Basolateral Amygdala (BA), Centrolateral Amygdala (CeL), and Centromedial Amygdala (CeM). * Markers and Signaling Molecules: Includes OTR (Ox