Brain and Behavior Final Exam

hypothalamus

deals with basic biological behaviors

• very heterogenous

• produces more than 20 neuropeptides

• autonomic nervous system

• controls pituitary and releases hormones

• basic motivated behaviors: eating, drinking

sleep

• natural biological rythym 

• happens naturall all the time in everyday life

• restoratoin of physical mental energy

Nocturnal

asleep during the day, awake at night

Diurnal

• awake during the day, asleep at night

• How humans sleep

Internal circadian rythym

our own internal biological clock (NOT SCN)

Exogenous

outside cues (ex. the sun)

phase shift

drastically throws off sleep cycle (ex. daylight savings, going abroad)

endogenous

__________ physiology

• body is effected by our internal systems too

intrinsically photosensitive retinal ganglion cells

_________ ___________ ______ ______ _____

• light with any wavelength comes into the eye and interacts with them

• activate melanopsin receptors on these ganglion cells (depolarize)

• Produce APs

• Axons synapse on SCN of hypothalamus where the APs go

• Glutamate released onto SC neurons (when light is on)

• SCN becomes active after interacting with glutamate so it releases GABA to pineal gland

• Inhibits melatonin production

Melatonin

Neurotransmitters made by pineal gland attach to other receptors in the brain to inhibit them and help us sleep

suprachiasmatic nucleus

• abbreviated SCN

• controls circadian rythym

• removal of SCN creates arythmytic sleeping activity

Adenosine

• the A in ATP

• fuel for neurons that depletes throughout the day

• As ATP is used this is produced as a byproduct

• sleep restores it into ATP

• becomes a NT after it binds to Adenosine receptors

• has A2a and A1 receptors

A2A

____ receptors

• if adenosine binds=excitatory (sleep neurons)

• stimulates GABA and melatonin release

A1

____ receptors

• if adenosine binds=inhibitory (awake neurons)

• Inhibits DA, NE, 5-HT, ACh, cortisol, glutamate release

EEG

• measures brain activity

• summation of EP/IPSPs

• Electrodes are placed in/labeled based on lobes in the brain

• 3-5 sleep cycles per evening (90 minutes each)

Amplitude

• height

• the higher it means that more neurons are doing the same thing

• synchrony means EPSPs

Frequency

• Hz

• waves/cycles per second

Awake brain waves

The brain waves at this time are very different because so much is going on

alpha activity

regular, low-medium waves

beta activity

• irregular, low-amplitude waves

• desynchrony

nonREM sleep

non rapid eye movement sleep

• 3 stages

  • Stage 1: 1-10 minutes

  • Stage 2 : 10-25 minutes

  • Stage 3: 25-40 minutes

Stage 1

• low frequency (4-10 Hz)

• medium amplitude

• hypnic jerks

• in here for 1-10 minutes

• first part of nonREM sleep

Stage 2

• sleep spindles

• k complexes

• Second stage of nonREM sleep

Stage 3

• slow wave sleep

• restorative

• memory consolidation

• cortical synchrony

• third stage of nonREM sleep

REM sleep

• rapid eye movement sleep

• low amplitude

• high frequency

• Theta and Beta, like awake, S1

• dream state

• loss of muscle tone (motor neurons inhibited so you don’t punch someone)

sleep spindles

• memory consolidation

• possibly IQ

Frontal lobe

• low activity

• poor dream organization

parietal lobe

• more active during sleep

• closer to occipital lobe

Temporal lobe

active in dreams that involve talking or listening

occipital lobe

• V1/primary visual/striate

• no input,low activity

• V2-4 extrastriate receives a lot of activity during REM

Histamine

NT in the brain that aids wakefulness and sleep (anti-histamine blocks this)

ACh

• dorsolateral pons

• arousal/focus

• stimulation of neurons causes cortical desynchrony

Norepinephrine

• locus coerulus

• neurons become quiet when asleep

• monoamine

• increases heart rate ventricles contract

serotonin

• raphe nuclei

• converted to melatonin

• chart looks similar to norepnephrine

• depressed people struggle with sleep

orexin

• lateral hypothalamus

• a mechanism of wakefulness

• also a mediator in sleep

• when hungry your ______ neurons will keep you awake so you can go find food

• fasting up regulates mRNA for _____ (______ production)

• stimulation of these neurons/receptors tells you to go eat

• increased consumption of food with ______ over expression

• when you eat→______ becomes active/activates dopamine neurons→dopamine neurons release dopamine NAc

• activated during learning

inhibits

______ VLPOA

• ACh in Pons

• NE in LC

• Seretonin in DR (dorsal raphe)

• Histamine in hypothalamus

• orexin

Narcolepsy

• Death/absence of orexin neurons

• sleep attacks, cataplexy, sleep paralysis

wakefulness

neural mechanisms of __________

• histamine

• ACh

• seretonin

• NE

• orexin

Insomnia

• overactive awake brain regions

• deficiency of GABA

• anxiety, stress, age, etc.

sleepwalking

motor cortex not inhibited by GABA

Why do we sleep?

• restore energy

• protection from predators

• reduced energy demand

• growth

• plasticity/learning

Recuperation theory

• restore and rejuvenate (stage 3 of sleep)

• Our bodies need to heal from being awake

• rebuilds bodily chemicals needed

• restores immune function

• removes waste products

  • free radicals

Brain plasticity theory

• brain needs changes to occur (plasticity)

• memory consolidation (stages 2-3 of sleep) [temporary memories→long term memories]

• Learning→sleep→recall→better retention of info

Evolutionary Adaptation Theory

• sleep patterns differ across species due to differing survival need

• Most mammals and birds display REM and slow wave sleep (stage 3)

  • humans can’t see well at night→sleep at night

  • tigers→no threat→sleep for a long time

  • small mammals→prey→sleep during the day awake at night

sunlight

__________ inhibits melatonin and vice versa (think of a type of light)

motivation

psychological process that induces/sustains behaviors to restore homeostasis

homeostasis

maintence of stable internal environment for factors necessary for survival

metabolic signals

endogenous chemical signals that tell us to stop/start eating

non-metabolic signals

exogenous signals that tell us to start/stop eating (non homeostatic)

satiety signals

• stomach expands

• you’re satiated

• They tell you to stop eating

• aka anorexigenic signals

hunger signals

stomach shrinks

stomach expands

_______ _______→machanoreceptors expand allowing NTs to flow in leading to APs that travel up the vagus nerve to the brain telling you to stop eating

vagal neurons

• synapse onto medulla areas

• NTS (nucleus of solitary tract) and area postrema

nucleus of solitary tract

• NTS

• receives signals that tell us our stomach has expanded (aka stop eating)

• has receptors that insulin, ghrelin, glucose, CCK(?), GLP-1, and Leptin bind to and tell it what to do so it can inhibit and tell oter neurons what is happening

glucose, fats, proteins

• main things we receive from food

• macromolecules

glucose

as you eat→glucose + insulin increases proportionally→insulin helps glucose enter cells for use/storage (glycogen) (hunger decreases)→blood glucose level decline, insulin increases→hunger and glucagon release increases (some stored supplies converted to glucose) enters blood, slowing hunger→eating

type 1 diabetes

not enough insulin

Type II diabetes

body becomes unable to recognize insulin levels (too much)

GLP1

• a glucagon like peptide that tells you to stop eating

• secreted by small intestine and colon

• stimulates insulin secretion

• receptors found in the brain

• short term satiety signal

CCK

• secreted by duodenum (where stomach and small intestine meet)

• is picked up by receptors in the duodenum

• taken by vagus nerve to the brain

• tells you to stop eating (short term satiety signal)

Leptin

• secreted by adipose tissue

• more adipose tissue = more _______=decrease in appetite

• LONG term satiety signal

• if you didn’t make this→satiety signal never arrives→appetite never decreases

Ghrelin

• short term orexinigenic (hunger) signal

• secreted by stomach

• receptors on stomach send signals up vagus nerve to the brain

• short term so it works every meal

orexigenic

__________ signals

• general group of signals telling you to EAT MORE

NTS

What region receives input from the body via the vagus nerve?

Decerebation

• take out half the brain and leave the hindbrain intact

• tells us we need the front of our brain for motivation

• can do:

  • posture (cerebellum)

  • walk

  • run

  • jump (only when provoked)

  • taste

  • reactivity

  • regulate meal size

• can’t do:

  • motivation

melanin

__________ concentrating hormone

• over expression/production→overeating/weight gain

orexin and MCH

_________ ____ _____ neurons project to much of the brain increases motivation to find food and eat

• made in cell bodies

• neuropeptides produced by separate neurons in the LHA

NPY and AGRP

• if activated causes a stronger reaction than orexin

• found in arcuate nucleus

• stimulation of neurons can lead to ravenous frantic eating (even when bitter)

• If you activate AGRP neurons food intake increases significantly

• there are ghrelin, leptin, and insulin receptors present on both areas

• ghrelin tells you to eat while the leptin/insulin says were not hungry

POMC neurons

• pro-opiomelanocortin

• active when we are not hungry anymore

  • CART

  • alpha-MSH

  • Leptin/insulin released bind to neurons tell them not to eat anymore

  • GLP-1 activates neurons

  • can be activated by any satiety neurons

sugar

_______ leads to dopamine release (NTS (tongue)→VTA→dopamine release)

Hunger and satiety

________ ___ ________ in the brain

• ________

  • orexin

  • MCH

  • NPY

  • AGRP

• ________

  • CART

  • MSH

lateral hypothalamus

_________ _________

• orexin and MCH are located here

arcuate nucleus

________ ________

• where NPY, AGRP, CART, and MSH are located

CART and MSH

• activated by satiety signals

• sated→stop

orexin, MCH, NPY, AGRP

Ghrelin is going to activate these neurons and satiety signals (GLP-1, leptin, etc) will inhibit

Associative learning

Pavlov’s dog was an example of classical conditioning which is generalized as _____________ __________

classical conditioning

• Pavlov’s dog

• neutral stimulus + uncondtioned stimulus = conditioned stimulus + unconditioned =conditioned response

zeitgeiber

• anything that starts a circadian rhythm

• think of the black light on the slide

• its a german term

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