UCSD PSYC 2 MIDTERM 1

Function of the Brain

The brain converts internal and external stimuli into electrochemical impulses.

Neurons

Process and transmit information.

Glial Cells (Glia)

Support, insulate, nourish, and clean up; also contribute to neural communication.

Dendrites

Receive signals; "tree-like" branches covered in receptors.

Soma (Cell Body)

Contains nucleus & organelles; integrates incoming signals.

Axon Hillock

Junction where action potential begins.

Axon

Long fiber that transmits the electrical impulse.

Myelin Sheath

Fatty insulation (made by glia) that speeds transmission.

Nodes of Ranvier

Gaps in myelin where signal regenerates.

Terminal Buttons

Release neurotransmitters into the synapse.

Signal Direction

Dendrites → Soma → Axon → Terminal → Synapse → Next Neuron

Sensory (Afferent) Neurons

Receive environmental input (e.g., light, sound, touch).

Motor (Efferent) Neurons

Output to muscles and glands.

Interneurons

Short, local connectors within brain regions or spinal cord.

Astrocytes

Star-shaped; regulate blood flow, synchronize firing of groups of neurons, form part of the blood-brain barrier.

Oligodendrocytes

Create myelin in the CNS; one cell can myelinate multiple axons.

Schwann Cells

Create myelin in the PNS; one cell = one axon segment.

Microglia

Act as immune cells; clean debris, dead neurons, and fight infections.

Radial Glia

Guide neuron migration during fetal development.

Blood-Brain Barrier (BBB)

Protects brain from toxins and infections.

Resting Potential

-70 mV (inside negative relative to outside).

Action Potential

Triggered when threshold (~-55 mV) is reached at axon hillock.

Sodium (Na⁺) Ions

Rush in during depolarization.

Potassium (K⁺) Ions

Exit during repolarization.

Na⁺/K⁺ Pump

Restores resting potential.

Saltatory Conduction

Speeds conduction by the impulse "jumps" between Nodes of Ranvier.

Reuptake

NTs reabsorbed by presynaptic neuron (e.g., serotonin).

Enzymatic Breakdown

NTs degraded by enzymes (e.g., acetylcholinesterase).

Autoreceptors

On presynaptic cell; detect released NTs → inhibit further release.

Negative Feedback

Postsynaptic neuron sends chemical message backward → stop release.

Amino acids

Glutamate (excitatory), GABA (inhibitory).

Monoamines

Dopamine, serotonin, norepinephrine.

Acetylcholine (ACh)

Muscle movement, memory.

Neuropeptides

Endorphins, substance P (modulate mood/pain).

Hindbrain

Medulla, pons, cerebellum; vital functions (breathing, heartbeat), movement coordination.

Midbrain

Tectum, tegmentum; visual & auditory reflexes, movement.

Forebrain

Thalamus, hypothalamus, limbic system, basal ganglia, cortex; sensory processing, emotion, motivation, cognition.

Ventricular System

Four cavities filled with cerebrospinal fluid (CSF).

Hydrocephalus

Blockage → ventricles enlarge and pressure increases.

Frontal Lobe

Motor output, speech (Broca's area), planning, reasoning, personality.

Parietal Lobe

Somatosensory input, spatial reasoning, math.

Temporal Lobe

Auditory processing, language comprehension (Wernicke's area), memory, emotion.

Occipital Lobe

Vision.

Central sulcus

Divides motor (front) & sensory (back) cortex.

Sylvian fissure

Divides temporal lobe from frontal/parietal.

Corpus callosum

Bridge between hemispheres.

Cingulate gyrus

Emotion & attention (part of limbic system).

Dura mater

Thick, tough outer layer ("tough mother").

Arachnoid mater

Middle, web-like layer; contains veins and CSF.

Pia mater

Thin, delicate layer that follows brain contours.

Somatotopic Maps

The motor and somatosensory cortices are organized by body region.

Contralateral control

Right brain → left body.

Photoreceptors

Rods (dim light, black & white) and cones (color, fine detail).

Fovea

Central focus point with dense cones.

Optic Chiasm

Where optic nerves cross; left visual field → right brain.

Dorsal Stream

V1 → Parietal lobe; spatial awareness, motion, location.

Ventral Stream

V1 → Temporal lobe; object & face recognition.

Receptive Field

Area of visual space that affects a given neuron's firing.

Lateral Inhibition

Retinal cells inhibit neighbors → enhances contrast.

Trichromatic Theory

3 cone types (red, green, blue).

Opponent-Process Theory

Pairs (red-green, blue-yellow, black-white).

Binding Problem

How does the brain combine sight, sound, touch, etc., into a unified perception?

Synchronous neural firing

Different sensory areas activate in rhythm when processing the same event.