NSCI 201

Electrophysiological Recording

Measure electrical activity of a neuron via intracellular and extracellular electrodes

Calcium Imaging

record transient changes in Ca2+ concentration via calcium sensitive dyes in order to study neural activity

Optogenetics

assess circuit physiology based on neuronal populations. Involves transducing light to activate channel proteins

topographic map

point to point mapping between sensory periphery and CNS

gray matter

cell bodies in the brain

cortex

brain's surface

nucleus

distinguishable mass of neurons

substantia

related neurons, less distinct than a nucleus

locus

a small, well defined group of cells

ganglion

collection of neuron cell bodies in the PNS

nerve

bundle of axons in the PNS

white matter

collection of axons

tract

CNS axons with a common origin and destination

bundle

a collection of axons that run together but do not necessarily have the same origin and destination

capsule

collection of axons that connect the cerebrum and brainstem

commissure

any collection of axons that connect the two sides of the brain

lemniscus

a tract that meanders through the brain like a ribbon

genetic analysis

study inherited diseases to see how genetic variation affects the structure and function of the nervous system

genome wide association studies

studies correlations

animal models

manipulate animal genes to mimic human conditions and test drugs / solutions

tract tracing

injecting a virus into a neuron in order to study its input and output

Where is the motor cortex located?

precentral gyrus

Where is the somatosensory cortex located?

postcentral gyrus

Where is the primary visual cortex located?

calcarine sulcus of occipital lobe

central sulcus

separates frontal and parietal lobes

cingulate gyrus

component of the limbic and motor systems

brainstem

midbrain, pons and medulla. Target and source for cranial nerves that deal with the sensorimotor of head and neck

Diencephalon

thalamus and hypothalamus

forebrain

amygdala and basal ganglia

ischemia

brief loss of blood supply; can cause cell death

stroke

The death of nervous tissue in the brain, usually resulting from lack of blood supply

blood brain barrier

endothelial membrane that protects the brain from toxins; only allows lipid soluble or actively transported substances to cross

meninges

three protective membranes that surround the brain and spinal cord. Dura mater, Arachnoid membrane, and Pia mater

Ventricular system

brain canals filled with cerebrospinal fluid

Glymphatic system

waste clearance system that clears metabolic waste and discarded protein; increases activity during sleep

Sensation

the ability to transduce, encode and perceive information generated by stimuli from both external and internal environments

proprioception

sense of where your body is in space

dorsal root ganglion

sensory receptor for the body

trigeminal ganglia

sensory receptor for face

mechanoreceptors

encapsulated afferent terminals that tine to specific features and have a low threshold (more sensitive)

free terminals

pain; higher thresholds, greater intensity causes greater pain

proprioceptors

low threshold, largest afferents (making them the fastest).

rapidly adapting afferents

afferents that fire at initiation and termination, and stop if stimulus is maintained

slowly adapting afferents

afferents that continue to fire with sustained stimulation

two point discrimination

minimum distance between two stimuli for them to be perceived as distinct

cutaneous sensation

a feeling of touch, pressure, vibration, tickle, heat, cold, or pain that arises in the skin

stregnosis

ability to identify something just by touching it

Merkel cell neurite complex

slow adapting (sustained) , high density, close to surface with a small receptive field. Sensitive to points, edges and curvatures, creating the highest spatial resolution

meissner afferents

rapidly adapting (dynamic), high density, small receptive field. High spatial resolution, and closest to the surface. Helpful for grip control

pacinian afferents

rapidly adapting (dynamics), low density afferents with a large receptive field and low response threshold (more sensitive). Sensitive to Vibrations

Ruffini afferents

slow adapting (sustained) afferents that help with sensing finger position and run parallel to stretch lines in the skin. They are sensitive to cutaneous stretching with movement

Muscle spindles

in striated (skeletal) muscles; 4-8 intrafusal muscle fibers surrounded by capsules of connective tissue

striated muscles

muscles for voluntary movement

group I afferents

in muscle spindles; send information regarding dynamic movement of muscle fibers

group II afferents

in muscle spindles; send information regarding sustained stretching extrafusal fibers

gamma motor neuron

a motor neuron that resensitizes muscle spindles to stretching and small changes by causing intrafusal contractions

Golgi tendon organs

sense changes in muscle tension(muscle contraction); distributed along collagen fibers, innervated by 1b afferents

first order neurons

pseudounipolar neurons whose cell bodies are located in the dorsal root ganglion; detect sensory events in the periphery and forward it to the spinal cord

second order neurons

begin in the gracile nucleus (lower body) or cuneate nucleus (upper body), move via the medial meniscus (where they cross the midline) and reach the thalamus

third order neurons

begin in the ventral posterior complex of the thalamus, move via the internal capsule and reach the cerebral cortex

Cutaneous information

Areas 3b and 1

Proprioceptive information

Area 3a

tactile and proprioceptive information

Area 2

Ventral posterior lateral nucleus

somatotopically maps information from the body

Ventral posterior medial nucleus

somatotopically maps information from the face

olfaction

smell; a chemical sense, and does NOT relay in the thalamus

odorants

airborne molecules

gustatory

taste; chemical sense

vomeronasal

mostly in animals; detection of pheromones (airborne odors from predators, prey, and partners)

trigeminal chemosensory system

responds to irritating / noxious chemicals that enter the nose or mouth

olfactory receptor neurons

in the olfactory epithelium in nose lining; relay info to pyriform cortex, as well as amygdala and hypothalamus for emotional reactions and memory of odours.
Bipolar and unmyelinated.

basal cells

stem cells that produce olfactory receptive cells; necessary because olfactory neurons are exposed to the outside and thus die easily

mucus

produced by Bowman's glands. Dissolve odorants and help them bind to receptors. Also contain aintibodies

Odour receptor proteins

G-protein linked receptors. Found on cilia. Some are selective to a singly chemical, some are activated by many.

olfactory bulb

axons of the receptor neurons project ipsilaterally to the bulb

glomeruli

spherical accumulations of neuropil that lie beneath the surface of the olfactory bulb. Target of ORNs; respond to subsets of molecules

olfactory nerve

made up of axons of the olfactory receptor neurons

combinational coding

most naturally occurring odors are blends of different odorants; each odorant is recognized by a specific combination of receptors

olfactory processing areas in the brain

accessory olfactory nuclei, amygdala, pyriform and entorhinal cortices, and olfactory tubercle

where are taste receptor proteins located

on taste cells (not neurons) inside taste buds

taste cells

innervated by cranial nerves VII (facial), IX (glossopharyngeus), and X (Vagus) which project to the nucleus of the solitary tract of the medulla

Sensory trasnduction

Salty and Sour are based on the presence of Na+ and H+ ions, so they just open ion channels. The other tastes are g-protein linked

bitter taste

low threshold to taste this in order to avoid toxic or poisonous food

taste papillae

Multicellular structures that stick out from the tongue surface, detect tastants over the full surface of the tongue. Surrounded by a trench which is lined on both sides by taste buds

Taste buds

contain taste cells, supporting cells, and basal cells (stem cells). Syanapse to gustatory axons

taste pores

small opening at the top of taste bud around which taste cells are clustered; concentrate tastants to present to cells

Where is taste processed?

Insular cortex; taste categories are maintained here

Trasnduction of taste

The receptor proteins transduce the tastants, causing the taste cell to depolarize. Neurotransmitters (including serotonin, GABA and ATP) are released from the presynaptic specialization at the base of the cell

labelled line theory

A theory of coding taste information where there is one specific pathway per taste. The most accurate theory.

Across Fibre version 1

each Taste cell is sensitive to all tastants in different combinations. Same afferents for multiple tastes

Across fibre version 2

each Taste cell is tuned to a particular taste, but a single afferent carries info from multiple taste cells. Combination of afferents creates the perception of taste

lens

adjusts thickness (and thus refractive power) via ciliary muscles in order to focus light on the retina

astigmatism

spherical aberration of the cornea resulting in multiple focal points

retina

light sensing neural tissue at the back of the eye

retinal pigment epithelium

darkly pigmented cell layer behind the retina which absorbs light

fovea

central part of macula which is responsible for central, high resolution vision. Contains exclusively densely packed cones, and has no blood vessels

optic disk

part where the nerve fibers leave the eyes, creates a blindspot. Has no photoreceptors

Photoreceptors

transduce light into neural electrical energy. They are hyper polarized by light

bipolar cells

pass photoreceptor information to the ganglion cells

saccades

rapid eye movements that shift the focus of the fovea