PSYC106 Midterm 2

• Acetylcholine = a chemical similar to an amino acid
• Most common treatments for Alzheimer's are meant to stimulate ACh receptors or prolong ACh release.
• Results in increased arousal.

• Decreased response to a stimulus as a result of recent exposure to it.
• Fatigue of receptors.
• Short term – visual illusions, aftereffects
• Long term – adaptations to adjust over weeks/months/years to change functions

Axons that brings information INTO a structure.Every sensory neuron is an afferent TO the rest of the nervous system (every motor neuron is an efferent FROM the nervous system)

• Suppression of pain
• Adaptive
• ex WWI found that peoples whose arms chopped off didn't report too much pain, 32% reported no pain!

• language impairment
• Damage Broca's area - language production- leads to aphasia

• From paper: Reducing excessive GABA-mediated tonic inhibition promotes
• functional recovery after stroke
• Treating: INHIBITION that happens days after stroke
• Drug L655-GABA-A receptor antagonist
• Stops inhibition that GABA produces
• Give 3 days after stroke

• Auditory Cortex
• In the Superior Temporal Cortex
• Active during "auditory imagery"

• Cochlea - Unrolled
• LOW PITCH
• have LARGE EFFECT in APEX (not base)
• 

• A group of subcortical forebrain structures lateral to the thalamus
• In Central Nervous System (CNS)
• Tail-like nucleus = Caudate Involved in motor control/functionParkinstons, Huntington's disease affects
• Learning and remembering HOW to do something, for attention, language, planning & other cognitive functions.
• Subdivisions exchange info w/other parts of cerebral cortex
• 

• Body Mass Index
• Measure of adult's weight in relation to their height:
• WEIGHT in kilos divided by square of HEIGHT in meters
• Obese = BMI of 30+

• Post brain damage:
• Language impairment minor or brief language impairment (NOT only area for language production)
• aka Nonfluent aphasia
• Regardless of area of damage
• May have deficits in comprehension when sentence meaning relies on a complex structure

• Chemical found in hot peppers, produces painful burning sensation by releasing substance P
• High doses damage pain receptors
• Also used in placebo studies

• Cocaine & amphetamine related transcript in
• hypothalamus
• Molecule that has effects that overlap w/cocaine amphetamines
• Produces low body wt - & heart issues
• Only drug to have effects on wt loss
• 

• Neural mechanisms in the spinal cord that generate rhythmic patterns of motor output
• example: mechanisms in wing flapping in birds, fin movements in fish, etc
• stimulus may ACTIVATE but doesnt CONTROL
• ex: Cats scratch themselves 3-4x/second. Cells in lumbar of spinal cord generate this rhythm & they will continue to do it if they're isoolated from the brain or muscles are paralyzed
• 

• "Snail"
• Contains 3 long fluid-filled channels
• Scalas: vestibuli, media, tympani
• Base of cochlea: Oval window - Vibrates - setting fluid in motion in the coclea
• Hair cells lie b/w the basilar membrane of the cochlea on one side & tectorial membrane on the other
• 

• Processes whisker information into the brain of rodents
• Located in somatosensory cortex

• Old way used in studying audition
• Old-fashioned imaging: Using 2-DG (2-deoxyglucose) modified form of glucose. Cells think its glucose. Grab when active – but BRAIN CANT USE so it gets stuck in the cells. So can give injection of 2-DG, play sounds – cut open brain & see where 2-DG is to see which cells were active
• Would need to examine brain POST-MORTEM

• Area of body connected to particular spinal nerve
• ex the 3rd thoracic nerve supplies strip of skin just above nipple & underarm
• Areas of dermatomes map body - massive overlap - 1/3 to 1/2 of area
• 31 sensory spinal nerves
• 

• "To shock throughout"
• Decreased activity of surviving brain neurons after damage to other neurons
• Could contribute to behavioral deficits after brain damage, increased stimulation could help

Loss of inhibition (resulting in activation?)

• Sensory.
• Clusters of sensory neurons carrying info into the spinal cord.
• Long axons go into muscle & spinal cord
• These axons are AFFERENTS INTO THE CNS
• (Cell bodies of the motor neurons are inside the spinal cord).
• Spinal animals: Stimulation of the dorsal root - can bypass the brain
• Stretch reflex = Spindles excited, AP to dorsal root
• 

• Extensor = Muscle that extends (straightens) the limbs
• Flexor = Muscle that flexes the limbs (bends)
• EXTRA INHIBITORY NEURON allows them to work together

• Will want more weight on other leg for support
• Nail info – wiring – stimulates neurons on SAME SIDE – wiring will cross midline – affects OTHER leg to do the right thing
• All of this done w/inhibitory neurons to adjust appropriately
• 

• Hunger signal/hormone/neurotransmitter
• Chemical released by the stomach during a period of food DEPRIVATION; also released as a neurotransmitter in the brain, where it stimulates eating

• Large subcortical structure, part of the basal ganglia
• Output from the caudate nucleus -> globus pallidus -> mainly to the thalamus -> relays to cerebral cortex
• Mostly resleases GABA
• Nuerons here show much spontaneous activity
• Constantly INHIBITING the thalamus
• 

• Simple sugar
• Neurons mostly rely on
• ONE OF ONLY NUTRIENTS THAT CROSS BLOOD-BRAIN BARRIER (except ketones- fat)
• The liver makes glucose from many carbs & amino acids & from glycerol- a breakdown product from fats

• 1. GLUCOSE levels rise, pancreas releases hormone INSULIN
• 2. Insulin causes cells to store excess glucose as fats & GYCOGEN
• 3. Glucose into cells suppresses hunger & decreases eating
• 4. Decreased eating lowers glucose level
• 

• 1. High insulin causes blood glucose to be stored as fats & glycogen
• 2. Difficult to mobilize stored nutrients
• 3. Hunger soon after each meal
• 

• 1. Low insulin levels
• 2. Glucose in blood cannot enter cells to be stored or use
• 3. Excrete glucose in urine, cells are starving

• Info from touch receptor below head enters spinal cord
• Passes toward brain through 31 spinal nerve (each have sensory & motor component)
• Each spinal nerve connects to a dermatome
• Touch pathway: light & deep.
• Pain pathway: diff axons for sharp, slow burning, painfully cold
• Temperature, pain & itch rely on unmyelinated axons
• Info -> Thalamus -> Somatosensory cortex

• contralateral
• medulla

COMPLETE cut through LEFT SPINAL NERVE

• receptors - sense pressure.
• respond best to sudden displacement/high freq vibrations
• Onion-looking thing.

• 1. Thermoceptors
• 2. Mechanoceptors
• 3. Nocioceptors - sense pain

• used to perceive pain, warmth, cold
• in epidermis layer - near base of hairs & elsewhere
• Unmylelinated or thinly myelinated

• PRESSURE-gated ion channel
• When pressure applied, ion channels stretch open, allowing sodium INSIDE
• When sodium IN - AP sent to brain
• At rest, ion channels closed

afferent

• Na (voltage gated sodium channel) is MUTATED on nocioceptors
• (pain neurons)

• glutamate
• glutamate & substance P

• Tissue damage -> chemicals activate terminals or make endings sensitive:
• histamine, prostoglandins, 5ht, serotonin
• Aspirin works here
• AP -> dorsal root ganglion -> spinal cord -> contralateral side ->

• Where opioids work
• agonists at mu receptors
• ascending communication pathways - dorsal - sensory - horn of spinal cord
• descending - pain modulation - ventral - pain signal diminished

• Pinna (outer ear)-> locates source of sound
• Pass through auditory canal
• Strike typmpanic membrane (eardrum) -> vibrates at same frequency
• Eardrum connects to 3 bones -> oval window (viscus fluid behind window)
• Inner ear -> Cochlea -> Basilar membrane -> cilia hairs are displaced by vibrations in the fluid
• The hair cells send AP's to auditory nerve -> into brain

• MECHANICALLY GATED
• Hair cells linked by tip link = molecular springs
• Attached to door on ion channel
• Fluid vibrates - hair moves - causes trap door to open - ion rushes in
• MORE POTASSIUM ON OUTSIDE - rushes in - becomes more positive on inside

• Inner:
• In a row.
• More important for hearing.
• Damage here more critical

• Outer:
• 3 rows

• Base
• Apex

• Auditory nerve (cochlear into brain stem)
• Sound crosses AND same side of brain into cortex (more from opposite side)
• Inferior colliculus = WHERE sound comes from
• Thalamus = In MGN medial geniculate nucleus
• Auditory cortex = A1(temporal) first sound info
• 

• "Where" sound info
• Tonotopic Map Organization
• Gradient sound - processed along different strips
• low - high

• Different parts respond to different parts of the cochlea - from BASE to APEX
• 

• 1. Intensity differences
• - shadow
• - where intensity is greater
• - ILDs = Interaural Loudness Differences

• 2. Arrival time
• - brain calculates same sound taking longer to get to 1 ear
• - ITDs = Interaural Time Differences
• 

• bands of cells respond differentially to TIME
• 

• flexion
• extension

• 1. Muscle Spindle
• - muscle fiber w/nerve endings wrapped around it
• - gets feedback signals to control & adjust input going in

• 2. Golgi tendon organ
• - nerve endings
• - nerve in tendon, where muscle connects to bone

• Stretched:
• - Both receptors excited (spindle & golgi tendon)

• Contracted:
• - GOLGI TENDON ACTIVATED ONLY
• 

• Sensory
• Motor

• Project to motor neurons
• Don't directly control muscle but have influences on motor neuron,
• Important for coordinating diff parts of reflex

• lateral
• medial

• Muscle neurons
• Muscles

• Female mating rodent reflex
• spinal autonomy
• Arches back – butt in air – moves tail – allows male to mount
• ONLY DOES this during this one part of this cycle
• Reason: Brain INHIBTS the reflex
• Hormones – go to brain – hypothalamus – Gets RID OF THE BLOCK that brain
• exercises on this reflex

• M1 = Primary motor cortex
• Next to central sulcus
• Hand & mouth MASSIVELY represented in homonculus
• Cells here are SENSITIVE TO DIRECTION

• IPSILATERAL control = SAME SIDE of body
• sensitive to alcohol
• fine coordination
• Damage affects aim, timing, alternation of movements
• Can do CONTINUOUS motor activity (since not starting or stopping an action)
• Damage - Saccades - eye movements - will be many short movements instead of fluid
• Involved in MOTOR LEARNING