Brain and Behavior EXAM 2

Sensory transduction

sensory info being converted to electrical signals

merkel disk

• shallow

• smaller receptive fields

• perception of shape/texture

• slow to adapt

meissners corpuscle

• shallow

• smaller receptive fields

• motion detection/grip control

• faster to adapt

ruffini endings

• deeper

• larger receptive fields

• skin stretch/tangital force

• slow to adapt

pacinian corpuscle

• deeper

• larger receptive fields

• perceptions of distant events through vibrations

• fast to adapt

Piezo channels

• mechanically gated ion channels

• found on sensory receptors

• non-selective

• permeable to Na+ and Ca²+

• open based on touch input sending APs up the sensory neuron to the spinal cord

free nerve endings

nerve endings responsible for pain and nocireception

conduction speed

relies on diameter of the axon and myelination thickness

ganglion

dorsal root ___________

• spinal chord dorsal horn neurons

• receives sensory info via NTs released

glutamate

fast-acting ionotropic receptor that sends EPSPs up the spinal cord and into the brain

medial lemniscal pathway

Ascending touch pathway

• AB fibers carry touch pressure through spinal chord/dorsal root

• Fibers synapse on neurons in dorsal column nuclei at lower medulla

• Medulla neurons project across midline; ascend contralaterally forming medial lemniscus

• medial lemniscus axons synapse on neurons in ventral posterior lateral nucleus of thalamus; project to primary somatosensory cortex

anterolateral system

Pain and temperature ascending pathway

• peripheral nocireceptors send info via unmyelinated c-fibers/myelinated a-fibers →dorsal horn neurons

• dorsal horn neurons project axons across midline to anterior lateral spinal cord→form anterolateral system

• ascending axons of spinal neurons synapse in the ventroposterior lateral nucleus of thalamus

• ventro. pos. laterla nucleus neurons project to primary somatosensory cortex

Thalamus

senses relay station in the brain (NOT SMELL)

Primary Somatosensory cortex

• anterior part of parietal lobe

• receives neurons arranged in a mapped sensory homunculus

• detects touch info from body

• communicates with posterior parietal cortex which is receiveing info from visual and auditory areas

• communicates with PFC for decision making

Pain Modulation Pathway

Descending Pathway

• midbrain PAG is the center for descendin inhibtion

• neurons in PAG project to locus coeruleus and nucleus raphe Magnus; norepinephrine and serotonin neurons are located respectively

• Both sets of neurons project down spinal cord and release norepinephrine/seretonin to reduce pain

• endorphins are also released at spinal chord; bind to u-opioid receptors and elicit both presynaptic and postsynaptic inhibition

light

composed of photons that travel in different wavelengths (ie.frequencies)

Wavelengths

• different _________ = different colors we see

• different _________ = different pitches we hear

Amplitudes

• different _________ = different brightness of color

• different _________ = different intensity/loudness

lens

• where light comes into the eye

• bends light and how it hits the retina (refraction)

• image upside down and backwards

retina

• photoreceptors (rods/cones) located here

• sensory receptors for light and transduction

Fovea

where the light gets focused on the back of the eye (retina)

photoreceptors

rods and cones

rods

• detect black and white

• located in the periphery

• have a lot more rods than cones

• low visual acuity

• much synaptic convergence onto bipolar cells

cones

• detect colors

• mostly in the fovea

• high acuity

• have short(v), medium(g), long(r) wavelengths

• missing one=colorblindness

• minimal synaptic convergence onto bipolar cells; individual direct paths to the brain

Rhodopsin

• contains opsin (light sensitive protein)

• contains retinal

• inactive in dark resulting in cGMP being active

Dark

• cGMP is plentiful inside the rod in the dark

• cGMP binds/opens Na+ channels

• allows Na+ to flow in and depolarize the rod

Light

• photon of light straightens retinal and activates rhodopsin

• activated rhodopsin→activates transducen→activates phosphodiesterase

• phosphodiesterase converts cGMP to 5’-GMP

• Na+ channels close; rod hypperpolarizes

more light

_______ _______=less glutamate

graded potentials

_______ _________=glutamate relreaase is dependant on # of breaks

glutamate

__________ released to bipolar cells

ganglion cells

bipolar cells synapse onto _________

superior colliculus

ganglion cells synapse onto _________ ________, etc.

off center

______ ________ bipolar cells

• contain AMPA receptors that glutamate can respond to

• less glutamate→less AMPA binding→less EPSPs

• respond more in the dark (depolarized)

• depolarize in dark hyperpolarize in light

on center

______ ________ bipolar cells

• mGLuR6

• causes IPSPS

• depolarize in light hyperpolarize in dark

receptive fields

depend on convergence; circular

horizontal amacrine

________ and _______ help synaptic convergence

ganglion

__________ cells produce AP when there is enough glutaate produced by bipolar cell

rods

• converge synaptically onto bipolar cells

• why details are hard t see in the dark

cones

• minimal synaptic convergence onto bipolar cells

• why detailed colors are easier to see

• individual direct path to the brain

left

_______ processed by the right side of the brain

optic chiasm

where axons cross in the brain (think grand canyon or chasm)

optic nerve

conglomeration of axons in PNS

optic tract

conglomeration of axons in the CNS

Vision

________ pathway to the brain

• left vis field field light reaches right side of retina; lens inverts image

• optic nerve axons from nasal half of retina cross optic chiasm

• Optic tract axons terminate in the lateral geniculate nucleus and the superior colliculus

• LGN neurons project to the PVC, V1

Lateral geniculate nucleus

part of the thalamus; layers of nerve that keep the visual pathways organized

retinotopic

________ organization

• organization of the visual cortex

Feature detection

• texture

• lines/edges

• patterns

• spaces

dorsal pathway

• posterior parietal cortex

• sensory integration (to sense where it is happening)

• where pathway

ventral pathway

• inferior temporal cortex

• deals with hippocampus (memories 

• size, shape, color, faces, and objects

• what pathway

fusiform gyrus

• bottom of the brain

• activated specifically to faces

graded potential

do hyper/depolarization proportional to how much light is coming in (photoreceptors, bipolar cells)

parahippocampul place area

• PPA

• opposite activity to fusiform face area (FFA)

Blindsight

• normal eyes, but loss of V1

• can still guess above chance

achromatopsia

no color vision due to damaged V4

prosopagnosia

• FFA damage or anything prior to that area

• cannot recognize faces

sound

composed of pressure waves that travel through air

frequency

• how many wave are happening

• measured in Hz

outer ear

• gathers sound; funnels it

• amplifies by compressing into canal

• ridges localize sound

• composed of auricle, pinna, and earlobe

• external auditory meatus (ear canal)

middle ear

• amplifies sound

• transmit info from ear drum to inner ear

• composed of tympanic membrane (ear drum), and ossicles (malleus, incus, stapes)

Tympanic membrane

• divides external and middle ear

• vibrates at its amplitude and frequency

• protects ear

ossicles

malleus, incus, and stapes

Inner ear

• fluid filled

• contains oval window, cochlea

Cochlea

• snail/spiral shaped

• scala vestibuli

• scala tympani

• scala media

oval window

stapes pushes and pulls membrane to create waves in fluid in inner ear

tonotopic

_______ organization

• organization of auditory system

basilar membrane

• varies by thickness and width

• each section vibrates to different frequencies

• tonotopically organized

scala vestibuli

• waves enter

• perilymph fluid

scala tympani

• waves exit until round window

• perilymph fluid

scala media

• in between

• endolymph fluid

hair cells

______ _____ with stereocilia

• rows of tiny hairs along th basilar membrane

• point of sensory transduction

• sound waves cause movement leading to APs

endolymph

• located outside of cells

• high in K+

• opposite of neurons (K+ inside of cell in neurons)

Tip link

connect neighboring stereo cilia

Auditory transduction

• at rest; cilia are closed vesicles are docked at ribbon synapse

• cilia move and tip links pull open ion channels

• K+ and Ca+ flow into cilia (from endolymph) when cilia open

• hair cells depolarize and open voltage gated Ca+ channels; vessicles fuse and release neurotransmitter

cranial nerves

• 12 pairs coming from the ventral surface of the brain

  • 3 afferent

  • 5 efferent

  • 4 aff/efferent

conduction deafness

outer/middle ear prevents sound from reaching inside

sensorineural deafness

hair cells fail to respons to either cochlea or cochlea nerve

central deafness

• damage to auditory brain areas

• can hear but difficulty processing what is heard

Cochlear implants

bypass middle ear and hear to directly stimulate the auditory nerve fibers

cochlear nuclei

cochlear nerve→______ __________

• tonotopic organization preserved

superior olivary nuclei

cochlear nuclei→______ _______ ______

• from both ears

• determine sound location

chemosensation

• taste and smell (utilize chemicals)

• Assess chemical comp. of substances to ingest

Gustation

inferior colliculus

Superior olivary nuclei→ ______ _______

• midbrain: tectum

• auditory relay

• helps sound localization

• also important for startle response

medial geniculate nucleus

inferior colliculus→____ _____ ______

primary auditory cortex

medial geniculate nucleus→______ _______ _______

• tonotopically organized

• picks up frequencies from the cochlea and basilar membrane

Wernicke

_________’s area

• language understanding

• temporal lobe

Broca

__________’s area

• language production

• frontal lobe

vestibular

____________ system

• contains the semicircular canals and vestibular nerve

• fluid filled with crystals that cause APs

• Gelatinous masses that sense when your head moves

gustation

• tongue

• has papillae, taste buds, taste cells, microvilli

papilla

bumps on tongue

taste buds

• inside grooves of papilla

• synapse onto facial nerve (cranial nerve 7), glossopharyngeal (cranial nerve 9), vagus nerve (cranial nerve 10)

  • talks to nucleus tractus solitarius in medulla about eating

taste cell

each one is responsible for a specific taste

microvilli

contains receptors that pick up bitter, salty, sweet, sour, and umami

salty

• Type 1 receptor

• Na+ channel (responds specifically to sodium)

• happens when you eat salt

sour

• Type 3 receptor

• H+ ion channel

• uses H+, K+ and Ca+

• releases seretonin

Umami, sweet, and bitter

• type 2 receptor

• GPCR

• Ca and Na

inferior colliculus

• receives info from the ear

• goes to medial geniculate nucleus of thalamus

auditory relay

• helps sounds localization

• important for startle response

Dorsal

_______ stream (auditory)

• where/how

• where is sound coming from

• Parietal lobe

Ventral

________ stream (auditory)

• have I heard this before?

• Temporal lobe