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Exploring Neuroscience
Definition: undulating displacement of molecules caused by changing pressure -has 3 physical attributes: frequency, amplitude, & complexity -travel @ a fixed speed of 1100ft/s -sound energy varies in wavelength
frequency
Definition: # of cycles a wave completes within a given amount of time -sounds w/ low pitch = slow wave frequency -sounds w/ high pitch = fast wave frequency
amplitude
Definition: perceived intensity or loudness; height of wave -sounds w/ single frequency = pure tones -sounds mix w/ wave frequencies = complex tones
pinna
funnel-like external structure of the outer ear designed to catch sound waves and funnel them into the external ear canal
ossicles
3 bones commonly known as the hammer, anvil, & stirrup reality = malleus, incus, & stapes -attach the eardrum to the oval window
cochlea
inner-ear structure containing the auditory receptor cells -has 2 sets of hair cells: i) 3500 inner hair cells & 12000 outer hair cells -only inner hair cells are auditory receptors
Sound Perception Pathway
1. pinna catches soundwaves and funnels them into the external ear canal 2. waves are amplified and directed to the eardrum, causing it to vibrate 3. this causes the ossicles to vibrate 4. ossicles amplify and convey the vibrations to the oval window (hitting against it) 5. vibration …
hair cells
sensory neurons in the cochlea tipped by cilia -movement of cilia changes hair cell's polarization & its rate of neurotransmitter (NT) release -movement towards tallest = depolarization: Ca2+ channels open, release NT onto dendrites of the cells that form the auditory nerve-->generatin…
basilar membrane
receptor surface in the cochlea that tranduces sound waves into neural activity -all parts of basilar bend in response to sound waves of any frequency -maximally responsive to frequencies that are mapped as the cochlea uncoils -high frequency sounds peak at thick (narrow) part of the b…
wernicke's area
secondary auditory cortex located at the rear of the left temporal lobe that regulates language comprehension
lateralization
process by which functions become localized primarily on one side of the brain
horizontal orienting
azimuth detection
vertical orienting
elevation detection
ventral audition pathway
decodes complex sounds or auditory-object recognition, including the meaning of speech sounds
dorsal audition pathway
plays a role in integrating auditory & somatosensory info to control speech production
broca's area
anterior speech area in the left hemisphere that functions w/ the motor cortex to produce the movement required for speaking
wernicke's aphasia
people who can speak fluently, but their language is confusing and makes little sense fluency, but poor comprehension
broca's aphasia
people who can't speak despite normal comprehension and intact physiology good comprehension, inability to speak fluently
phoneme
simplest unit of sound
morpheme
smallest meaningful unit of language
semantics
meanings of words, sentences, & phrases
syntax
grammar & sentence structure
lexicon
words available
prosody
characteristic melody & rhythms of speech
discourse
conversation at level of social interaction
neologism
made up word
major components of movement control
1) cerebrum: conscious control 2) brainstem: automatic movement control 3) spinal cord: automatic movement control
Integration of sensory & motor processes
1. visual information required to locate the target (visual = LGN) (auditory = MGN) 2. Frontal lobe motor areas plan & command the movement (knowing this = parietal lobe) 3. spinal cord carries info to target -motor neuron in motor cortex sends signal down spinal cord & affects muscles…
motor sequence
determined by the prefrontal cortex; movements are performed as sequences, with one held in readiness while an ongoing sequence is being completed
frontal lobes
(i) prefrontal cortex: plans complex behavior based on a goal (ii) premotor cortex: produces the appropriate motor sequences (iii) primary motor cortex: specifies how each movement is carried out
mirror neurons
found in premotor cortex -a neuron that is active during the observation or action of a specific task -active upon thinking about the task
brainstem
species-typical behaviors (e.g. swimming, grooming, nest making, chewing, defensive mechanisms)
spinal cord
facilitates complex motor patterns (e.g. scratching, walking)
damage to section of brain
no rehab: reduction of damaged area rehab: enlargement/accommodation of other areas this is evidence of plasticity
cortical spinal tract
main efferent pathway -focus on layer V -axons descend into brainstem; some go to brainstem nuclei; emerge on ventral surface of brainstem (bump on each side) -conscious control over skeletal muscles
corticobulbar tract
conscious movement of eye/jaw/face muscles -most likely to descend and synapse in the brainstem -doesn't make sense to travel down spinal cord since muscle targets are above neck
lateral cs tract
does cross over -branches at the medulla to cross over to opposite side -moves contralateral digits and limbs -synapses w/ interneurons & motor neurons -interneurons synapse w/ motor neurons that innervate muscle -motor neurons project to muscles of the body -originates in neocortex…
ventral cs tract
does not cross over -moves (same-side) muscles of the midline body (trunk) -originates in neocortex and terminates in spinal cord
limb muscles
they are paired -extensors: move (extend) limb away from the trunk -flexors: move limb towards trunk -coordinated movement requires extensor contraction as flexor relaxes or vice-versa
tectospinal tract
important in dorsal tectospinal tract -input from visual system to coordinate head & neck movements to visual stimuli
rubrospinal tract
origin: red nucleus -input from motor cortex & cerebellum to control arm muscles
red nucleus
restores some motor function lost as a result of cs system damage (pyramidal tract lesions)
agonist muscle
more work for movement increase firing rate of agonist motor neuron
antagonist muscle
goes against movement decrease firing rate of antagonist motor neuron
basal ganglia & movement force
input from: 1. all areas of the neocortex, limbic cortex, & motor cortex 2. the nigrostriatial dopaminergic system from the substantia nigra -project back to the motor cortex via thalamus & substantia nigra -range of functions in addition to movement: habit learning, motivation, emoti…
hyperkinetic symptom
increase in movement; writhing & twitching movements called dyskinesias (i.e. Huntington's Disease)
hypokinetic symptom
decrease in movement; ridgity & difficulty initiating and producing movements (i.e. Parkinson's Disease)
flocculus
small, dense lobe involved in eye movements and balance -divided in 2 hemispheres -lateral parts: movement of limbs, hands, feet, & digits -ventral parts: movement of face & midline of body -primary fissure: separates anterior/posterior lobes -postereolateral fissure: separates flocc…
cerebellar peduncles
cerebellum connects to brain via these superior: main output of cerebellum (goes mostly to midbrain) middle: info from contralateral cerebral cortex inferior: input carrying sensory info of where the body is in space
main functions of cerebellum
1. timing: movements & perceptions 2. movement accuracy -error correction: compares intended movement w/ actual movement and makes the necessary adjustments
layers of the cerebellar peduncles
innermost: granule cell layer (small, tightly packed neurons) -input from mossy fibers--> project to purkinje cells middle: purkinje cell layer (1-cell thick) -output for entire cerebellar cortex; inhibitory connections onto cerebellar deep nuclei outer: molecular layer (mostly granul…
inferior olive
climbing fibers-->excitatory input to purkinje cells brainstem's largest nuclear group -tracts originate here to form part of the inferior cerebellar peduncle
nocioception
perceive pain, temperature, itch -free nerve endings -consists of small neurons w/ little to no myelination
hapsis
-perceive fine touch & pressure -mechanical stimulation of the hair or tissue -consists of large myelinated neurons
proprioception
perception of the body in space -sensitive to the stretch of muscle, muscle tendons, & joint movement -consists of the largest myelinated neurons
rapidly adapting receptor
responds briefly to the beginning & end of a stimulus ex) haptic receptors: meissner's corpuscles, pacinian corpuscle, & ruffini
slowly adapting receptor
responds as long as the stimulus is present ex) merkel's receptor or hair receptors
lateral ST tract
nocioception (pain, T, itch)
dorsal ST tract
-hapsis (fine touch & pressure) -proprioception (body in space)
medial lemniscus
tract formed by axons of second order neurons from the dorsal column nuclei
spinal nerves
cervical thoracic lumbar sacral
prefrontal cortex
plans complex executive behavior -decision making -damage to this region often results in breaking social and legal rules due to faulty decision making
premotor cortex
received instructions from prefrontal cortex -produces appropriate complex movement sequences -damage to this region = sequences can't be coordinated and the goal can't be reached -organizes motor sequences via mirror neurons
primary motor cortex
receives organized motor sequences from premotor cortex -specifies how each movement is carried out
simple movement
blood flow increases in the hand area of the primary motor cortex as an indiv presses down on a lever w/ their finger
movement sequence
blood flow increases in the premotor cortex as an indiv performs a sequence of movements
complex movement
blood flow increases in the prefrontal, temporal, & parietal cortexes as an indiv uses a finger to trace a route in a maze
psychosomatic pain
emotional component of pain
neurogenic pain
neuron damaged; no specific nocioceptor involved
neuropathic pain
sensitization causes increased perception of pain, if persistent--->chronic pain
referred pain
site of cause is not the site of pain perception -nociocpetors detect damage/potential damage -may be responsive to mechanical, chemical, or thermal stimuli -pain in body organs interpreted as body surface pain
pain perception
. initial response (damage) 2. inflammation: sensitized polymodal neurons, resulting in hyperalgesia (decrease pain threshold) (i) reticular formation & PAG (arousal) (ii) tectum (orienting responses) (iii) amygdala (emotional responses) (iv) hypothalamus (hormonal & cardiovascular r…
visceral pain
visceral pain 1. wide variance on sensitivity -hollow vs. solid organs -hollow organs are more sensitive to pain 2. pain & injury relationship is weak -GI tract: burning is not perceived, but twisting is excruciating -hear: extremely sensitive to decrease in blood flow 3. exaggerate…
gate theory of pain
activities in different pathways compete -haptic-proprioceptive stimulation can reduce pain perception by activating inhibitory interneurons that reduce nocioception
periaqueductal gray (PAG)
electrical stimulate decreases pain PAG neurons excite brainstem pathways -these excited pathways project to dorsal spinal cord to inhibit lateral st tract neurons
globus pallidus internal (GPi) activation pathways
if direct pathway is activated = GPi is inhibited & the pathway is allowed to produce movement -if indirect pathway is activated = GPi is activated & it inhibits the thalamus which blocks movement
glabrous skin
skin on the palms of the hands & feet, the lips, & the tongue is hairless--sensitive to a range of stimuli
nocioception pathways
free nerve endings for pain: SLOW -free nerve endings for temp: SLOW damage/irritation to dendrite or surrounding cells releases chemicals stimulating the dendrite to produce APs
hapsis pathways
messners corpuscle = touch: RAPID -pacinian corpuscle = flutter: RAPID -ruffini corpuscle = vibration: RAPID -merkel's receptor = steady skin indentation: SLOW -hair receptors = flutter or steady skin indentation: SLOW
proprioception pathways
muscle spindles = muscle strech: RAPID -golgi tendon organs = tendon stretches: RAPID -joint receptors = joint movement: RAPID
dorsal-root ganglion neuron
contains one long dendrite; only the tip is responsive to sensory stimuli -every spinal segment is characterized by a dorsal-root that contains neurons of many types: - each type responds to a particular kind of somatosensory info
dorsal spinothalamic (st) tract
formed by haptic-proprioception axons located in the dorsal part of the spinal cord 1. these axons synapse in the dorsal-column nuclei at the base of the brain 2. then cross over to other side of brainstem & ascend to medial lemniscus pathway 3. then synapse in ventrolateral thalamus w…
lateral spinothalamic (st) tract
-formed by nocioceptive axons 1. synapse w/ neurons in the dorsal part of the spinal cord & these neurons send their axons to the other side of the spinal cord 2. on ventral side--> form ventral ST tract 3. which joins the medial lemniscus in the brainstem 4. is then send to the vent…
monosynaptic reflex
simple spinal reflex that is formed by a single synapse between a sensory neuron and a motor neuron
affective aggression
associated with fear/threat reactive; defensive -correlated with medial hypothalamus, dorsolateral PAG; cerebral cortex is not required
predatory aggression
proactive; premeditated aggression -correlated with lateral hypothalamus or ventral PAG; cerebral cortex is required
gonadal hormones
-androgens & estrogens alter 5-HT (serotonin) receptor expression -high testosterone lowers stress perception overall BUT-->testosterone increases responsiveness to social threats
oxytocin
regulates maternal behavior (maternal aggression) -depends on dam's level of anxiety -oxytocin sensitizes the amygdala
emotions
cognitive interpretations of subjective feelings
motivation
behavior that seems purposeful and goal-directed
smell
receptor surface: olfactory epithelium -composed of receptor cells and support cells -each receptor cell sends a process that ends in 10-20 cilia into a mucous layer (olfactory mucosa) 1. chemicals in air diffuse into layer interacting with cilia -->metabotropic activation--> AP 2. o…
orbitofrontal cortex (OFC)
area of the prefrontal cortex located behind the eye sockets; receives projections from dorsomedial nucleus of the thalamus -plays a role in emotional/social behaviors as well as eating
vomeronasal organ
organ that receives input of pheromones -connects to amygdala & hypothalamus 1. detected by organ 2. then sends axons to accessory olfactory bulb 3. connects mainly w/ amygdala & hypothalamus--> plays a role in reproductive & social behaviors
5 types of taste
. sweet 2. sour 3. salty 4. bitter 5. umami = savory
taste
receptors: microvilli -base of taste bud is contacted by branches of afferent nerves that come from cranial nerves: 7 (facial), 9 (glossopharyngeal), & 10 (vagus) -facial nerve--> anterior 1/3 of tongue -vagus nerve--> posterior 1/3 of tongue -glossopharyngeal nerve--> other parts of …
innate releasing mechanisms (IRM)
activators for inborn, adaptive responses that aid an animal's survival
regulatory behaviors
behaviors motivated by an organism's survival -controlled by homeostatic mechanisms -hypothalamus maintains homeostatis by acting on both the endocrine system & ANS to reg. internal enviornment
non-regulatory behaviors
neither required to meet the basic survival needs of an animal nor controlled by homeostatic mechanisms -includes sexual intercourse behaviors to parenting to curiosity
factors that control hypothalamus hormone-related activity
1. feed back loops: hypothalamus initiates a cascade of events-->secretion of hormones, but pays attention to how much is released -when a certain level is reached it stops hormone stimulating signals 2. neural control: regulates other brain structures (i.e. limbic system & frontal lobe…

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