BIO1251: Lectures 20-25

pinna/auricle

definition & location in ear

folded funnel to the ear canal that consists of skin, cartilage, and muscles

external ear

external auditory meatus (ear canal)

definition & location in ear

channel thatcarries soundwaves from the outer ear to the eardrum

external ear

tympanic membrane (eardrum)

definition & location in ear

barrier between external/middle ear that vibrates when sound waves reach it

ossicles

definition, order, and location in ear

three bones that transmit sound vibrations from the eardrum to the inner ear

1. malleus / hammer

2. anvil / incus

3. Stapes / stirrup

middle ear

cochlea

definition & location in ear

spiraled, fluid-filled hollow chamber of bone that recieves input from the middle ear

located in inner ear

tonotopic map

organization of auditory information in the cochlea; lower frequency pitches activate hair cells at the apex

cochlear nerve

nerve that carries sensory information from the cochlea to the brain

semicircular canals

fluid-filled bony tubes in inner ear that detect head’s rotational movements

vestibular nerve

nerve that carries spatial information from the semicircular canals to the brain

sound

wave of compressed air

amplitude and frequency in sound waves

volume and pitch (Hz)

sine wave

simplest kind of sound; one pure tone

sonic boom

pressure change as object exceeds the speed of sound

Organ of Corti

structure in the cochlea that produces nerve impulses in response to sound vibrations

tectorial membrane

location and function

inside the Organ of Corti; moves the stereocilia of hair cells

stereocilia’s function in the Organ of Corti

detect tectorial membrane’s movement and transmit information to cochlear nerve

hair cell mechanically-gated ion channels

ion channels in Organ of Corti that are pushed open by the tectorial membrane reacting to sound waves

cochlear implants

when are they used

device that codes signals into electrical pulses and bypasses the damaged inner ear

used when hair cells are damaged but auditory nerve is still intact

auditory neural network

Organ of Corti (hair cell and spiral ganglion neuron) → brainstem/midbrain interneuron → medial geniculate nucleus (thalamus) → auditory cortex

sound localization

process by which the brain detects the location of a sound source by detecting the time lag in signal between the left/right brainstem nuclei

primary auditory cortex

part of the auditory cortex involved in frequency detection

secondary and tertiary auditory cortex

parts of the auditory cortex involved in integrating information and detecting harmony/rhythm

vestibular system

system responsible for maintaining balance, spatial orientation, and movement coordination

layers of skin (top to bottom)

epidermis, dermis, subcutaneous tissue

mechanoreceptors

role in touch sensation

nerve endings in a cushioned capsule that detect tactile stimuli

have mechanically-gated ion channels that open due to force on membrane

neural pathway for touch / mechanosensation

mechanoreceptor → brainstem (medulla) → thalamus (VPL) → somatosensory cortex

receptive field

region of space in which a stimulus will activate a particular sensory receptor neuron

neural pathway for olfaction (smell)

olfactory epithelium receptor → olfactory bulb (forebrain) → olfactory cortex (temporal lobe)

anosmia

inability to smell

neural network for gustation (taste)

taste cell in taste bud → brainstem (medulla) → thalamus (VPM) → gustatory cortex (on border of front/temporal lobe)

papillae

specialized bumps on tongue that contain taste buds

5 basic tastes

bitter, sour, salty, sweet, umami

emotion

complex bodily reaction to stimuli

feelings

conscious reaction of body state and interpretation of the corresponding emotion

limbic system

definition/structures and location

control center for emotion that includes the hypothalamus, hippocampus, and amygdala

located deep in the temporal lobe

amygdala

brain region that activates during dangerous/frightening stimuli and increases memory retention of these events

Douchenn smile

phenomenon in which smiling causes one to feel happiness

Capgras delusion

belief that one’s loved one is an impostor

phobia

abnormal fear response to particular stimuli

stress

physiological response to demand/threat

adrenaline and cortisol

hormones involved in stress

eustress

healthy stress

distress

unhealthy stress

HPA axis

the system formed between the hypothalamus, pituitary gland, and adrenal gland

stress-brain loop

cycle of chronic stress involved with decreased regulation of cortisol

gastrulation

stage of embryonic development where the three germ layers are formed

ectoderm

outer germ layer that forms the nervous system and skin

three germ layers (outside to inside)

ectoderm, mesoderm, endoderm

neural tube

one-cell thick structure that rolls up from a region of the ectoderm and gives rise to the central nervous system

spina bifida

birth defect that occurs due to an improper closure of the neural tube and vertabrae in embryo

neural crest

structure derived from the ectoderm that gives rise to the peripheral nervous system

6 steps in NS development

1. proliferation

2. migration

3. differentiation

4. axon pathfinding

5. dendrite growth and synapse formation

6. pruning

proliferation

stage of nervous system development in which neural stem cells divide to produce neurons

migration

stage of nervous system development in which new neurons stop dividing and migrate by “climbing” radial glia

radial glia

elongated neural progenitor cells that guide migrating neurons in NS development

differentiation

stage of nervous system development in which neurons turn on specific genes to become specialized

axon pathfinding

stage of nervous system development in which neurons form axons that, with the growth cone, detect their target in brain

growth cone

specialized “sensing device” that detects an axon’s correct path by receiving information from other cells in the environment

dendrite growth and synapse formation

stage of nervous system development in which neurons use “lock and key” proteins to find the right partners

pruning

stage of nervous system development in which neurons/synapses are pruned to make networks efficient

Autism Spectrum Disorder (ASD)

etiologically and clinically heterogenous group of disorders involving impaired social interaction, disrupted communication, and repetitive behaviors / restricted interests

Theory of Mind

capacity to understand/differentiate another individual’s mental state

Sally Ann test

dyslexia

learning disorder that causes difficulty reading/processing written language

Alzheimer’s Disease (AD)

progressive neurodegenerative disorder that leads to reduced brain structure size and inflammation; characterized by amyloid plaques and neurofibrillary tangles

amyloid plaques

definition/cause

abnormal clumps of proteins that disrupt signals and lead to neural death

due to overproduction of amyloid-beta peptide in neurons

in Alzheimer’s disease

neurofibrillary tangles

tangles inside neurons, caused by abnormal tau protein, that disrupts neuronal networks and synapses

tau

protein that stabilizes the neuron’s cytoskeleton

Apolipoprotein E alleles

alleles that regulate the protein involved in transporting lipids/cholesterol

plays a role in AD

Acetycholinesterase inhibitors

drugs that block the breakdown of ACh in the synapse

used for early stages of AD

Intravenous (IV) infusion monoclonal antibody treatments

treatment for AD that targets betaamyloid protein

microglia remove the antibodies attached to the betaamyloids

Parkinson’s Disease (PD)

neurodegenerative disease in which substantia nigra neurons die, affecting movement

substantia nigra neurons

neurons in the substantia nigra (midbrain) that produce dopamine and form a network with the basal ganglia

Lewy bodies

definition & disease

abnormal protein clumps inside neurons

associated with PD

L-DOPA

function, use, and side effects

precursor to dopamine that is used to treat Parkinson’s

side effect = dyskinesias

dyskinesias

involuntary, erratic movements

Huntington’s Disease (HD)

definition and cause

neurodegenerative disease that causes nerve cells to degenerate, caused by an inherited expansion mutation in the Huntington gene

frontotemporal dementia (FTD)

disorder characterized by a loss of neurons in the front and temporal lobes, causing atrophy and leading to problems with behavior, emotion, and communication

Amyotrophic Lateral Sclerosis (ALS)

progressive disease that damages motor nerves in the brain and spinal cord, eventually rendering the brain unable to control muscle movements (including speaking, eating, moving, and breathing)

traumatic brain injury (TBI)

brain injury caused by a force trauma to the head

chronic traumatic encephalopathy (CTE)

progressive and fatal brain disease associated with repeated traumatic brain injuries; patients experience cognitive problems, personality changes, erratic behavior, and depression

major depressive disorder

chronic mood disorder involving sadness, feelings of worthlessness, irritability, fatigue, loss of interest/hope, cognitive slowing, and suicidal ideation

Biogenic Amine (Monoamine) Theory

theory that depression stems from low monoamine neurotransmitters

Monoamine oxidase (MOA)

enzyme that breaks down monoamines in the presynaptic terminal

monoamine oxidase inhibitors (MOAIs)

drugs that inhibit MOA, thus increasing the action of monoamine neurotransmitters

“cheese effect”

side effect of MOAIs

buildup of toxicity because MOAIs inhibit the breakdown of dietary amines

serotonin shock syndrome

severe condition caused by excessive serotonin levels when combining medications

Imipramine

tricyclic class drug that inhibits the reuptake of dopamine, norepinephrine, and serotonin

selective serotonin reuptake inhibitors (SSRIs)

drugs used to treat severe depression that inhibit the reuptake mechanisms of serotonin

Seasonal Affective Disorder (SAD)

type of depression related to seasonal changes

Bipolar Disorder (Manic Depression)

mood disorder where one shifts between manic and depressive states every few months

anxiety disorders

mental health disorder characterized by persistent and disproportionate fear/worry that causes significant distress or impairment

psychotic disorders

group of disorders characterized by psychosis, delusions, and hallucinations

psychosis

loss of contact with reality

positive symptoms of schizophrenia

adding something that is not present

delusions, hallucinations, and disordered speech/thoughts

negative symptoms of schizophrenia

deficits in normal functioning

dopamine hypothesis

link between high dopamine levels and schizophrenia