Neuroscience Basics – Lecture on Brain Structure & Human Uniqueness

Vocabulary flashcards covering key terms from the lecture on human brain structure, neuron density, and the functional divisions of the forebrain, midbrain, and hindbrain.

Neuron Density

The number of neurons relative to body size; humans have the highest neuron density of any animal, granting greater computational power.

Computational Power (Brain)

The brain’s capacity to perform complex processing, largely tied to the sheer number of neurons in humans.

Prospection

The uniquely human ability to mentally simulate future scenarios and learn from imagined outcomes.

Triune Brain (Outdated Model)

An older three-layer model of the brain—reptilian (instincts), limbic (emotions), and neocortex (rational thought); useful as a schematic but not anatomically precise.

Reptilian Brain / Brainstem

Deep, evolutionarily ancient brain region governing basic survival instincts and autonomic functions.

Limbic System

Mid-level brain structures (e.g., amygdala, hippocampus) involved in emotion, motivation, and memory; shared by all mammals.

Neocortex / Cerebral Cortex

The newest evolutionary layer of the primate brain responsible for higher cognition, language, and rational thought.

Forebrain

Largest brain division including the neocortex, limbic system, thalamus, and others; underlies higher-order processing.

Midbrain

Brain region atop the brainstem handling basic vision, hearing, sleep–wake cycles, arousal, and involuntary motor control.

Hindbrain

Lowest brain division (including cerebellum and medulla) managing vital life functions such as breathing, balance, and digestion.

Frontal Lobe

Front part of the cerebral cortex; critical for planning, decision-making, and simulation of future events.

Prefrontal Cortex

Anterior portion of the frontal lobe; supports rationality, impulse control, and advanced simulation abilities.

Broca’s Area

Region in the left frontal cortex controlling voluntary speech production and related motor movements.

Primary Motor Cortex

Strip of cortex that directs voluntary skeletal muscle movements, mapped contralaterally (left brain → right body).

Corpus Callosum

Thick bundle of nerve fibers connecting the brain’s hemispheres, enabling inter-hemispheric communication.

Amygdala

Limbic structure involved in emotional processing, especially fear and threat detection.

Hippocampus

Limbic structure essential for forming and retrieving long-term declarative memories.

Cerebellum

Structure at the back of the brain coordinating balance, fine motor control, and some cognitive functions.

Gyri (Singular: Gyrus)

Raised ridges on the cerebral cortex that increase surface area for neuronal processing.

Sulci (Singular: Sulcus)

Grooves or fissures between gyri; together with gyri create the brain’s ‘wrinkled’ appearance.

Surface Area (Brain)

Total cortical sheet size; humans possess the greatest cortical surface area due to abundant gyri and sulci.

Connectome

The complete map of neural connections in a brain; “I am my connectome” highlights identity rooted in neural wiring.

Language (Human)

A unique human capacity combining grammar, syntax, and temporal reference, enabling idea transfer without direct action.

Simulation Learning

Acquiring knowledge by mentally rehearsing actions and consequences instead of performing them physically.

Brainstem

Structure connecting brain and spinal cord; houses midbrain, pons, and medulla, managing essential autonomic tasks.

Pons

Part of the brainstem regulating sleep, arousal, and some sensory functions.

Medulla

Lowest brainstem section controlling heart rate, breathing, and other vital autonomic functions.

Reflex Arc

Rapid, involuntary response path that travels only to the spinal cord, bypassing the brain for speed.

Locked-In Syndrome

Condition where forebrain consciousness may remain intact while voluntary motor pathways are disrupted, leaving only basic hindbrain functions.

Neuron vs. Body Energy Use

Humans devote ~25% of energy intake to brain activity—more than any other species—because of extensive neuron counts.