Neuroanatomy and Research Methods

Input Zone of a Neuron

Dendrites collect and process information from the environment or other neurons.

Integration Zone of a Neuron

The cell body (soma) and axon hillock integrate incoming electrical signals.

Conduction Zone of a Neuron

The axon propagates electrical impulses rapidly over long distances.

Output Zone of a Neuron

Axon terminals release chemical neurotransmitters to target cells.

Multipolar Neurons

Neurons featuring multiple dendrites and a single axon; the most common CNS type.

Bipolar Neurons

Neurons with a single dendrite at one end and a single axon at the other.

Unipolar Neurons

Neurons with a single process that divides into input and output branches.

Motor Neurons

Large neurons that transmit neural commands from the CNS to muscles or glands.

Sensory Neurons

Neurons directly affected by environmental stimuli, conveying signals toward the CNS.

Interneurons

Neurons with short local axons that analyze information and communicate within local circuits.

Presynaptic Membrane

The specialized membrane of the presynaptic axon terminal, containing voltage-gated calcium channels and docking sites for synaptic vesicles.

Synaptic Cleft

A narrow intercellular gap of 20 to 40 nm separating presynaptic and postsynaptic cells.

Postsynaptic Membrane

The specialized domain on the postsynaptic dendrite or cell body, studded with specific neurotransmitter receptors (ligand-binding proteins) that detect released transmitters.

Synaptic Vesicles and Receptors

Small, hollow spherical membrane structures inside the presynaptic terminal that hold thousands of molecules of chemical neurotransmitter.

1) Arrival of action potential

2) Ca2+ Influx

3) Vesicle Fusion and Release

4) Receptor Binding

5) Postsynaptic Potential

6) Signal Termination

Steps Neurotransmission

1) Action potential propagates down axon and depolarizes presynaptic axon terminal

2) depolarization triggers voltage-gated Ca2+ channels to open (down gradient)

Steps 1 & 2 of Neurotransmission

3) Ca2+ influx causes vesicle fusion with presynaptic membrane and exocytosis into synaptic cleft

4) transmitter release into cleft and bind to matching postsynaptic receptors causing conformational changes for ion channels to open

Step 3 & 4 of Neurotransmission

5) ions flowing creates an EPSP or IPSP

6) synaptic transmission is rapidly stopped, so the message is brief and accurately reflects the activity of the presynaptic cell

Steps 5 & 6 of Neurotransmission

via enzymatic degradation or reuptake into presynaptic terminal via specialized transporter proteins

how does neurotransmission termination occur

Excitatory Postsynaptic Potential (EPSP)

A depolarizing potential caused by sodium influx.

Inhibitory Postsynaptic Potential (IPSP)

A hyperpolarizing potential caused by chloride influx or potassium efflux (prevents overfiring)

Oligodendrocytes

Glial cells that form myelin sheaths around axons in the central nervous system.

Schwann Cells

Glial cells that form myelin sheaths around peripheral nervous system axons.

Astrocytes

Star-shaped CNS glia that regulate blood flow, modulate synapses, and define brain structure.

Microglia

Tiny, mobile immune-like cells that engulf cellular debris and pathogens.

Nerve

a bundle of neuronal axons wrapped together in PNS

Somatic Nervous System

Interconnects the brain and spinal cord with skeletal muscles and sensory organs (voluntary muscle movement)

Autonomic Nervous System

Involuntarily regulates internal visceral organs, glands, smooth muscle, and the heart (involuntary muscle movement)

I) olfactory

II) optic

III) oculomotor

IV) trochlear

V) trigeminal

VI) abducens

VII) facial

VIII) vestibulocochlear

iX) glossopharyngeal

X) vagus

XI) accessory

XII) hypoglossal

cranial nerves

8 Cervical (neck)

12 Thoracic (torso/trunk)

5 Lumbar (lower back)

5 Sacral (pelvic)

1 Coccygeal (tailbone)

spinal cord segments

Ventral (Front) Root

Carries motor fibers projecting from motor neurons in the ventral horn of the spinal cord to muscles and glands.

Dorsal (Rear) Root

Carries sensory fibers conducting information from peripheral body receptors into the dorsal part of the spinal cord. Cell bodies of these sensory neurons reside in the dorsal root ganglion

Sympathetic Nervous System

Prepares the body for action during emergencies, known as the fight-or-flight response.

Parasympathetic Nervous System

Helps the body relax and conserve energy, known as the rest-and-digest response.

Frontal Lobe

Cerebral lobe crucial for motor control, decision-making, and executive function.

Parietal Lobe

Cerebral lobe containing the postcentral gyrus, mediating somatosensory perception.

Temporal Lobe

Cerebral lobe essential for auditory processing, speech perception, and memory formation.

Occipital Lobe

Posterior cerebral lobe dedicated primarily to visual processing.

Corpus Callosum

A thick band of myelinated axons bridging the left and right cerebral hemispheres.

bisects the brain into left and right halves

sagittal plane

divides brain into anterior and posterior (front and back)

frontal plane

divides the brain into superior and inferior sections

horizontal plane

side and middle

lateral and medial

heat/front and tail/back

rostral (anterior) and caudal (posterior)

Toward the back/top of head vs. toward the belly/bottom of brain.

dorsal and ventral

Same side of body vs. opposite side of body.

ipsilateral and contralateral

Carrying information INTO a region vs. carrying information AWAY from a region.

afferent and efferent

Gray Matter

Brain areas dominated by neuronal cell bodies and dendrites that process information.

White Matter

Axonal tracts sheathed in myelin that transmit information across distant brain sites.

Basal Ganglia

Interconnected subcortical nuclei critical for motor control and movement initiation (forebrain)

Cerebral Cortex, Basal Ganglia, Limbic System (forebrain)

telencephalon

Thalamus, Hypothalamus, Epithalamus (forebrain)

diencephalon

midbrain, pons, medulla

brainstem

Amygdala

Anterior temporal lobe structure critical for emotional processing and fear conditioning.

Hippocampus

Medial temporal lobe structure crucial for learning, spatial navigation, and memory consolidation.

Medulla Oblongata

Portion of the brainstem governing vital autonomic centers like heart rate and respiration.

Meninges

Three protective membrane layers enclosing the brain and spinal cord: dura mater, arachnoid, and pia mater.

dura mater

thick, outermost layer of the meninges surrounding and protecting the brain and spinal cord

arachnoid membrane

web-like middle layer. spans the subarachnoid space, which is filled with cerebrospinal fluid (CSF) and blood vessels

pia mater

the delicate innermost membrane enveloping the contours and sulci of the brain surface

Ventricular System

Glymphatic System

A specialized glia-mediated waste clearance system active during sleep.

Invasive Techniques: surgical lesioning, tissue extraction, implantation of intracranial electrodes, or microinjections.

Noninvasive Techniques: EEG, MRI, CT, and fMRI.

Techniques for Studying the Structure and Function of the Nervous System

Circle of Willis

An arterial ring at the base of the brain providing redundant collateral blood circulation.

Nissl Stain

Histology technique that outlines cell bodies by staining RNA and ribosomes.

Golgi Stain

Histology technique that reveals detailed cell morphology and dendritic branching.

Functional MRI (fMRI)

Neuroimaging technology that detects blood-oxygen-level-dependent (BOLD) changes.

Somatic Intervention

Research approach altering a physical structure and measuring resulting behavioral changes.

Reductionism

Scientific strategy of breaking complex systems down into smaller constituent parts.