NEUROSCIENCE: WEEKS 1-3

action potential

action potential

event in which ions move down the axon rapidly, allowing neurons to transmit messages quickly and efficiently

anions

negatively charged ions

cations

positively charged ions

intracellular

inside of the cell

extracellular

outside of the cell

cell membrane

separates the interior from the exterior of the cell

phospholipid bilayer

what the semipermeable cell membrane is composed of

ion channels

allows ions to move in and out of the cell, made of specialized proteins

resting potential

neuron’s voltage at rest; around -70 mV

membrane potential

the difference in charge between the inside and outside of the cell; the voltage along the membrane

diffusion

causes ions to go from an area of higher concentration to an area of lower concentration along a concentration gradient

electrostatic pressure

causes ions to flow towards oppositely charged areas

axon initial segment

location of most ion channels that let ions in

threshold

the minimum membrane potential needed to trigger an action potential

depolarization

increase in neuron’s membrane potential, excitatory inputs, neuron becomes more positive

hyperpolarization

decrease in neuron’s membrane potential, inhibitory inputs, neuron becomes more negative

frequency

a bigger charge will increase the _______ of an action potential

potassium leak channels

channels that are always open to K+, can enter based on diffusion and electrostatic pressure

voltage gated sodium channels

channels that let Na+ in when the neuron reaches a certain voltage

voltage gated potassium channels

channels that let K+ out when the neuron reaches a certain voltage

sodium/potassium pump

channels that pump out 3 sodium and bring in 2 potassium to bring the neuron back to the resting membrane potential

resting potential

stage of the action potential where the neuron is at rest and at resting membrane potential

sub-threshold depolarization

stage of the action potential where there are jumps in the membrane potential below the threshold line

depolarization

stage of the action potential where the threshold is crossed and the membrane potential spikes (+40 mV), becomes more permeable to Na+

absolute refractory

stage of the action potential where the membrane potential has reached is peak; VG Na+ channels are INACTIVATED (NO MORE ACTION POTENTIAL) and VG K+ channels open

relative refractory

stage of the action potential where the membrane potential is back below the resting potential and there is a relative chance of another action potential

return to rest

stage of the action potential where the Na+/K+ pump transports sodium out and potassium in, original resting membrane potential is restored

multiple sclerosis

Disease where immune system attacks myelin sheath and causes communication problems between the brain and the rest of the body

input zone

First segment of the neuron; dendrites and soma

integration zone

Second segment of the neuron; axon initial segment

conduction zone

Third segment of the neuron; axon, myelin sheath, nodes of ranvier

output zone

Fourth and final segment of the neuron; axon collaterals, axon terminals

neurotransmitters

These are released once an action potential reaches the axon terminal

synaptic cleft

Where do neurotransmitters go after leaving the presynaptic neuron?

post-synaptic

Dendrites are what kind of cell?

pre-synaptic

Axon terminals are what kind of cell?

Multipolar neurons

Most common type of neuron, collects most information, one axon, many dendrites

Pseudo-unipolar neurons

Neurons that send touch information to spinal cord, two processes; one brings information to cell body, one brings information away

Bipolar neurons

Sensory neurons fond in olfactory epithelium, eye retina, ganglia of vestibulocochlear nerve, two distinct processes from cell body, one dendritic process, one axon

Sensory/afferent neurons

Neurons that carry information from PNS and sensory receptors to CNS

Motor/efferent neurons

Carries information from the CNS to the motor organs (muscles)

Relay interneurons

Neurons with long axons to convey signals to far away targets, one region to another

Local interneurons

Neurons with short axons that convey signals to nearby neurons in local circuits

Longitudinal fissure

Gap between the two hemispheres of the cerebrum

Transverse fissure

Gap between the cerebrum and cerebellum

Optic chiasma

Place where the two optic nerves cross

Infundibulum

Place where pituitary gland is attached; behind optic chiasma

Superior colliculus

Important for visual pathway; orientation with eye movements

Pineal gland

Sleep and wake cycles (Circadian rhythm)

glial cell

Provides support and protection to the neurons, maintains homeostasis, cleans up debris, and forms myelin

astrocyte

Type of glial cell; provides mechanical and metabolic support for neurons

• Forms barrier along capillaries

• Regulates blood flow

• Transfers mitochondria to neurons

microglia

Type of glial cell; immune cell, protective, cleans up debris

• Most prominent immune cells of the CNS

  • Surrounds and breaks down any debris after brain damage

ependymal cells

Type of glial cell; forms inner lining of ventricles, facilitates production of CSF

• CSF homeostasis

• Brain metabolism0

• Clearance of waste from the brain

satellite cells

Type of glial cell; protects neurons and ganglia in the PNS

• Muscle-resident stem cells for tissue repair

oligodendrocytes

Type of glial cell; forms myelin sheath around multiple axons in the CNS

• Myelinates 30-40 axons with its ‘arms’

Schwann/neurilemma cells

Type of glial cell; forms the myelin sheath around PNS

• 1 myelin segment on 1 axon

• Development, maintenance, function, and regeneration of peripheral nerves

Substantia Nigra

Midbrain region that produces dopamine with DOPAMINERGIC NEURONS, loss leads to Parkinson's disease

Lewy Body

Abnormal protein deposits associated with Parkinson's disease

Limbic System

Brain structures involved in learning, memory, cognitive functions, emotional regulation, and sense of smell

Hippocampus

Part of limbic system, involved in long-term memory

Cingulate Gyrus

Part of limbic system, contributes to emotional processing, pain perception, processing speed, memory, and attention

Fornix

Primary EFFERENT white matter tract that carries information away from the hippocampus

Mammillary Bodies

Part of limbic system, important for memory and sense of direction

Amygdala

Part of limbic system, involved in processing fearful and threatening stimuli

Cerebrum

Largest part of the brain, involved in higher cognitive functions

Cerebellum

Coordinates muscular control and balance, located at the back of the brain

Brain Stem

Controls automatic functions like breathing and heart rate

Midbrain

Part of brain stem involved in sensory/motor functions and reflexes

Pons

Part of brain stem involved in movement and cranial nerve functions

Medulla Oblongata

Part of brain stem involved in autonomic functions like heartbeat and breathing

Neurons

Specialized cells that transmit information in the nervous system

Dendrites

Branch-like structures that receive information from neighboring neurons

Soma

Cell body of a neuron, contains important cellular components

Axon Initial Segment

Section of neuron where threshold responding occurs

Myelin Sheath

Insulative material that covers axons, increases transmission efficiency/effectiveness, prevents leak channels and leakage of ions

Nodes of Ranvier

Gaps between myelin sheath where action potentials regenerate

Saltatory Conduction

Rapid jumping of action potential along myelinated axons

Lateral Ventricle

Largest of four fluid-filled cavities in the brain, holds CSF

Cerebrospinal Fluid

Fluid produced in choroid plexus, fills cerebral ventricles

Schizophrenia

Mental disorder characterized by enlarged ventricles

Gray Matter

Thalamus and Hypothalamus; involved in sensory integration and homeostasis

Thalamus

Central hub for sensory pathways, relays sensory information

Hypothalamus

Subcortical structure involved in homeostasis and hormone regulation

Basal Ganglia

Group of forebrain nuclei involved in reward circuitry and motor control

Caudate Nucleus

Part of basal ganglia, important for movement and goal-directed behavior

Globus Pallidus

Part of basal ganglia, controls conscious and proprioceptive movements, INHIBITORY

GABA

Inhibitory neurotransmitter, dysfunction can lead to movement disorders and mood/depression

Gall

believed in discrete view of the brain, specific brain structures for specific functions

Flourens

believed in holistic view of the brain, all structures required for all mental processes

Broca and Wernicke

shifted back to discrete view, discovery of brain regions

Trepanation

(Prehistoric - 1600s); circular piece of bone is drilled from the skull

Frontal Lobotomy

(1800s - 1960s); severing connections in the prefrontal cortex

Anterograde Amnesia

type of memory loss; inability to form new memories

Ramon y Cajal

neuron doctrine, produced anatomically precise drawings of neurons

Brodmann

studied cerebral cortex, demarcated the brain

Neuroimaging tools

MRI, X-Rays, PET imaging

Optogenetics

injecting a virus for light-activated ion channels to transiently see brain activity

Dorsal

superior/top

Ventral

inferior/bottom

Rostral

towards the nose