Psychopharmacology and Vision: Key Concepts and Mechanisms

Acetylcholine

A neurotransmitter that plays a key role in the peripheral nervous system and autonomic nervous system.

Acetylcholinesterase

An enzyme that breaks down acetylcholine in the synaptic cleft.

Agonist

A substance that facilitates the effects of a neurotransmitter by enhancing its action.

Amino Acids

Glutamate (EPSP)

Amino acids

The building blocks of proteins

Amphetamines

Stimulants that act as potent agonists of dopamine

AMPT

A dopamine antagonist that inhibits the enzyme tyrosine hydroxylase

Analgesia

The inability to feel pain

Antagonist

A substance that inhibits the effects of a neurotransmitter by blocking its action.

Bipolar cells

Receive visual info. from the photoreceptors

Black widow spider venom

A potent agonist of acetylcholine that causes excessive muscle contractions.

blindspot

Visual information travel to non-image forming areas i.e.

Botulinum

A toxin that acts as an antagonist to acetylcholine

Brightness

The perception of light intensity

Choline acetyltransferase (ChAT)

An enzyme responsible for synthesizing acetylcholine from choline and acetyl-CoA.

Cholinergic Drugs

Substances that affect the neurotransmitter acetylcholine

Ciliary muscles

muscles that relax or contract the Lens and alter the shape of the lens

Complex Cells

Neurons that respond to the movement of lines with a particular orientation.

Cones

Photoreceptors responsible for color vision and high acuity in bright light.

Cornea

The transparent outer layer of the eye that helps focus light.

Curare

A plant-derived substance that acts as an antagonist at nicotinic acetylcholine receptors

Cytochrome Oxidase (CO) Blobs

Regions in V1 associated with metabolic activity and color processing. project to thin stripe of V2

Depolarization in vision

bipolar cells depolarizes the ganglion cells and cause an action potential.

Dopamine β-hydroxylase

An enzyme that converts dopamine to norepinephrine.

Dopamine

A neurotransmitter involved in movement

Dopaminergic Drugs

Medications that influence dopamine levels and activity in the brain.

dorsal stream stretches from

Begins with neurons of thick stripes of V2

Ascends into posterior parietal cortex

Dorsal Stream

The pathway in the brain responsible for processing spatial location and movement

Endogenous opioids

Naturally occurring peptides in the body that bind to opioid receptors to reduce pain and induce feelings of pleasure.

Excitatory neurotransmitter

A type of neurotransmitter that causes depolarization of the post-synaptic neuron

Fluoxetine

An antidepressant that acts as a serotonin agonist by inhibiting the reuptake of serotonin.

Fovea

The central region of the retina with a high concentration of cones

GABA aminotransferase

An enzyme that breaks down GABA

GABA

The principal inhibitory neurotransmitter in the brain and spinal cord.

Ganglion cells:

Receive visual info from bipolar cells

Glutamate

The principal excitatory neurotransmitter in the brain and spinal cord.

Glutaminase

An enzyme that converts glutamine to glutamate

Hue

The aspect of color perception determined by the wavelength of light.

Hypercomplex Cells

Neurons that respond to lines with a specific orientation that terminate at a certain point.

Inactivation

The process by which neurotransmitters are removed from the synaptic cleft to terminate their action.

Inhibitory neurotransmitter

A type of neurotransmitter that causes hyperpolarization of the post-synaptic neuron

Iris

The colored muscle that regulates the size of the pupil.

Koniocellular Sublayer

layers between LGN involved in processing color information.

Lateral Geniculate Nucleus (LGN)

A thalamic structure that processes visual information from the retina before sending it to the primary visual cortex.

Lens

A transparent structure that changes shape to focus light onto the retina.

LSD

A hallucinogenic drug that acts as a direct agonist at serotonin receptors

Magnocellular Layers

layers 1 and 2 of the LGN that contain large neurons sensitive to movement.

Moclobemide

An antidepressant that acts as a norepinephrine agonist by blocking the enzyme MAO-A.

Monoamine oxidase (MAO)

An enzyme that breaks down monoamines

Monoamines

A class of neurotransmitters that includes serotonin

Neurotransmitter

A chemical messenger responsible for transmitting signals between neurons.

Nicotine

A stimulant that acts as an agonist at nicotinic acetylcholine receptors

Norepinephrine

A neurotransmitter that functions in both the central nervous system and the autonomic nervous system

OFF Cells

Ganglion cells that are excited when light hits the surround

ON Cells

Ganglion cells that are excited when light hits their center

Opioids

Peptides that act as neurotransmitters

optic nerve

a bundle of axons of

the ganglion cells

Pale CO Stripes

Stripes in V2 that process orientation

Parvocellular Layers

layers 4-6 of the LGN that contain small neurons sensitive to color and detail.

PCPA

A serotonin antagonist that inhibits the enzyme tryptophan hydroxylase

Peptides

Short chains of amino acids that can act as neurotransmitters

Photopigments

Proteins in photoreceptors that change structure in response to light

Photoreceptors

rods and cones

Phototransduction

The process by which light stimuli are converted into changes in membrane potential in photoreceptors.

Pupil

The adjustable opening in the center of the eye that controls the amount of light entering.

Receptive Field

The specific area of the visual field that influences the firing rate of a neuron.

Receptor Binding

The process by which neurotransmitters attach to receptors on post-synaptic neurons to exert their effects.

Reserpine

A drug that interferes with the storage of monoamines in vesicles

Retina

The innermost layer of the eye containing photoreceptors that convert light into neural signals.

Reuptake

The process by which neurotransmitters are reabsorbed by the presynaptic neuron after they have performed their function.

Rods

Photoreceptors in the retina that are sensitive to low light levels but do not provide color information.

Saturation

The perception of color purity

Serotonergic Drugs

Substances that affect serotonin levels and activity in the brain.

Serotonin

A neurotransmitter that affects mood

Simple Cell

A type of neuron in the visual cortex that responds to specific orientations of light.

Storage

The process of packing neurotransmitters into synaptic vesicles for release during synaptic transmission.

Striate Cortex (V1)

The primary visual cortex that processes visual information from the LGN.

Synthesis

The process of creating neurotransmitters from precursors through enzymatic reactions.

Thick CO Stripes

Stripes in V2 that process orientation

Thin CO Stripes

Stripes in V2 that primarily process color information.

Tryptophan hydroxylase

An enzyme that converts tryptophan to serotonin.

Ventral stream stretches from

Begins with the neurons in thin and pale stripes of V2

Projects into the inferior temporal cortex

Ventral Stream

The pathway in the brain responsible for processing form and color

Vesicular monoamine transporters

Proteins that transport monoamines into synaptic vesicles for storage.

Visual Association Cortex (V2)

A region that processes complex visual information

Visual Stimulus

The light waves that are detected by the human eye

What are the fibers that carry visual information from the LGN to the cortex called?

Optic radiation fibers

What effect does hyperpolarization have on neurotransmitter release in vision?

It causes the cell to release less neurotransmitter (glutamate).

What follows the retina in the visual pathway?

Optic nerve

what is Blindsight

A condition where individuals are unaware of their visual capabilities but can respond to visual stimuli.

What is hyperpolarization in vision?

A change in the cell's membrane potential that makes it more negative.

What is the area of the brain that processes visual information beyond the primary visual cortex?

Extrastriate cortex

What is the first structure in the visual pathway?

Retina

What is the pathway called after the optic chiasm?

Optic tract

What is the primary visual cortex also known as?

Striate cortex (V1)