Neuroanatomy

(Lecture 1) Disembodied Mind

Dualism (The body is the biological machine and spirit the seat of personality, memory, choice, food, and emotion)

Embodied Mind

- The mind as created by the brain along with the rest of the body
- Monism, Physicalism, Idealism, Mind-Brain Identity

Biopsychology Perspective

Physical processes fully cause and underlie all behaviors

Somatic Intervention

Change a somatic variable and see its behavioral effect

Behavioral Intervention

Change a behavior to see its somatic effect

Corpus Callosum

Connects the two hemispheres of the brain

Transcranial Magnetic Stimulation

A technique that permits scientists to temporarily enhance or depress activity in a specific area of the brain

Language

Lateralized to the left hemisphere

Contralateral Control

Each hemisphere of the brain controls the opposite side of the body

Blindsight

A condition in which a person can respond to a visual stimulus without consciously experiencing it

(Neuroanatomy) Neurons

Transmit and compute information (directly responsible for behavior)

Glia

Indirect, supportive role

Oligodendrocytes

Myelination of axons in the CNS

Schwann Cells

Myelination of axons in the PNS

Radial Glia

Structural support

Microglia

Cell repair

Astrocytes

- Nutritive role, responsible for blood flow changes with neural activity
- Clean up of extracellular chemicals
- Modulating neuronal signaling, necessary for some learning

Anterograde Transport

From the cell body to axon terminals

Retrograde Transport

From axon terminals to cell body

fMRI

Measures signals of oxygenated blood flow which is increased when astrocytes detect neural activity

Central Nervous System (CNS)

Brain and spinal cord

Peripheral Nervous System (PNS)

Sensory and Motor Pathways

Motor Pathways

Autonomic and Somatic Nervous System

Autonomic Nervous System

Sympathetic (Arousal/Fight or flight), Parasympathetic (Antagonistic to Sympathetic), and Enteric (digestion)

Nerve

A bundle of axons outside the CNS

Tract

A bundle of axons within the CNS

Spinal/Cranial Nerves

Includes sensory and motor (somatic and autonomic)

Cervical

Neck/arms

Thoracic

Chest/Upper back

Lumbar

Lower back/legs

Sacral

Between hips (posterior)

Cranial Nerves

12 pairs of nerves that carry messages to and from the brain

Olfactory Nerve

Sense of smell

Optic Nerve

Vision from the eye to the brain

Vagus Nerve

Digestion, heart rate

Dorsal/Ventral

Back/Belly

Anterior/Posterior (Rostral/Caudal)

Front to back / Head to tail

Medial/Lateral

Middle/Side

Vertebra of Spinal Column

Spinal cord runs through the hole

Spinal Cord

- Reflex and signal processing, transmission
- Motor neurons - ventral part (center gray matter)
- Sensory neurons - outside the spinal cord in the dorsal root ganglion
- Fiber tracts (white matter) run up/down the outside of the cord

Interneurons

Neurons that communicate internally in one structure

Projection Neurons

Enter/leave a structure to communicate with other neurons located in a different region

Afferent

Sensory, towards the brain

Efferent

Motor, away from the brain

Learning with the spinal cord

Rats with their spinal cord cut from their brain still learns that when it puts its foot in the water it gets shocked

Meninges

Protective membranes that surround the brain and spinal cord
- Dura mater - Tough membrane next to the skull
- Arachnoid mater - Interconnecting structural matrix
- Sub-arachnoid lymphatic-like membrane (new)
- Sub-arachnoid space - filled with cerebrospinal fluid
- Pia mater - thin membrane next to the brain

Ventricles

- Two lateral, third and fourth
- Filled with cerebrospinal fluid (made by choroid plexus in the ventricles), released to immerse brain then be absorbed into bloodstream
- Provide cushioning, buoyancy, nutritive/waste removal

Schizophrenia

Cell death, enlarges ventricles and loss of gray matter

Central Canal

A fluid-filled channel in the center of the spinal cord

Medulla

Respiration, heart rate, sensory/motor pathways, arousal/sleep

Pons

Arousal/sleep, sensory/motor pathways

Cerebellum

Fine motor control, balance, sensory-motor adjustment

Cerebral Cortex (Cerebrum)

Higher processing

Gryi (gyrus)

Ridges

Sulci (sulcus)

- Shallow grooves separating the gyri
~ Divides the cerebral hemispheres into lobes

Fissures

Large sulci

Occipital Lobe

Visual processing

Parietal Lobe

- Somatosensory processing
- Attention
- Visual motion

Temporal Lobe

- Audition
- Memory (Not just here)
- Language comprehension
- Visual recognition

Frontal Lobe

- Motor control
- Planning, problem solving
- Working memory
- Personality (Phones Gage), emotionality

Optic Chiasm

Optic nerves from each eye cross over and then project to the opposite half of the brain

Sagittal View

Split in half left and right

Limbic System

Emotional information, value

Hippocampus

A neural center located in the limbic system that helps process explicit memories for storage

Amygdala

A limbic system structure involved in memory and emotion, particularly fear and aggression

Nucleus Accumbens

Dopamine-rich area critical to reward/addiction

Olfactory bulb

Brain center for smell, located below the frontal lobes

Cingulate gyrus

Strip of limbic cortex, emotion and pain

Mammillary body

- Connected to the hippocampus
- Episodic memory

Hypothalamus

Fleeing, fighting, feeding, sex drive (4 Fs)

Basal Ganglia

- Striatum (Caudate and Putamen
- Globus Pallidus
- Habits/stimulus-response learning

Coronal Radiations

Axons to and from the thalamus

Association fibers

Axons between cortical areas

Embryonic Divisions

- Telencephalon
- Diencephalon
- Mesencephalon (Midbrain)
- Metencephalon
- Myelencephalon
- Spinal cord

Hindbrain

Myencephalon:
- Medulla
Metencephalon:
- Pons
- Cerebellum

Midbrain

Mesencephalon:
- Tectum (Superior Colliculus - Visual orientation to sensory stimuli and Inferior Colliculus - Auditory localization)
- Tegmentum (Substantia nigra - Motor function, deterioration causes Parkinson's disease)
- Ventral Tegmental Area - Reward, motivation

Forebrain

Diencephalon:
- Thalamus
- Hypothalamus
Telencephalon:
- Cortex
- Limbic System
- Basal Ganglia

Coronal Plane

Divided into front and back

Horizontal Plane

Divided into top and bottom

Sagittal Plane

Divided into left and right

Nissl Stain

Selectively stains cell bodies

Nucleus

Collection of cell bodies in the CNS (also obviously means the nucleus of a cell itself, but not in this case)

Ganglion

Collection of cell bodies in the PNS

Ipsilateral

The same side/hemisphere (the opposite of contralateral)

(Neurophysiology) Electrical Polarization

Inside of a cell is more negative than the outside at rest (-60 mV compared to the outside)

Leak Channel

Open all the time and permeable to K+ and (to a lesser extent) Na+

Ion Channel

- Protein tunnel in the cell membrane, typically selective for a particular ion
- Can be gated by neurotransmitters (ligands) or voltage

Na+

Flows into the cell, concentration is 15x greater outside than inside

K+

Flows out of the cell, concentration is 20x greater inside than outside

Equilibrium Potential

- Each ion has an equilibrium potential based on concentration and valence
- For potassium, -80 mV
- For sodium, +55 mV
- For chloride, -60 mV
- For calcium, +150 mV

Nernst Equation

Concentration gradient (outside / inside) relative to the valence charge corresponds to equilibrium potential

Goldman-Hodgkin-Katz Equation

Membrane potential that results from the contribution of all ions that can cross the membrane (basically a weighted average based on each ion's permeability)

Resting Membrane Potential

At rest, ions flow through leak channels
- Membrane potential sits around -60 mV (Potassium is weighted more heavily than sodium in the average, more permeable)

Receptor Potentials

- Channels in the dendrites and soma are ligand gated, a particular ion flows through following its concentration gradient until equilibrium potential or the channel closes
- Local membrane potential changes based on influx/outflux

Excitatory post-synaptic potential (EPSP)

Action potential --\> NT release to synapse --\> EPSP in the next neuron

Graded Potential

The more neurotransmitters released/binding, the more channels open, the higher the receptor potential
- Potential diminishes over time and space, which would be bad if it went through the whole axon like that until it reached the axon terminals (so we do action potentials instead)

Depolarization

- Excitatory neurotransmitter binds (e.g. glutamate)
- EPSPs, Na+ rushes into the cell and make it more positive

Hyperpolarization

- Inhibitory neurotransmitter binds (GABA)
- IPSPs, Cl- enters into the cell and make it more negative
- K+ leaving through leak channels is a hyper polarizing force

Temporal Summation

Combined effect of EPSPs or IPSPs produced in rapid succession (they sum together with a longer time)

Spatial Summation

Multiple synapses firing at different locations at one time to sum together