PSY 430 - Midterm

Major divisions of the brain

• hindbrain

• midbrain

• forebrain

sulcus

grooves of the brain (wrinkles)

gyrus

folds of the brain

fissure

deep sulcus

Why do we have so many folds in the brain?

More surface area as a result which means more space for neurons leading to increased cognitive capacity

Hindbrain is composed of the following:

• Cerebellum

• Medulla oblongata

• Pons

Cerebellum (functions)

balance, movement, attention (timing)

Medulla oblongata (functions)

extension of spinal cord and vital reflexes (breathing, coughing, sneezing) + opiate receptors

Pons (function)

the “bridge“ for contralateral control

Midbrain is composed of the following:

• tectum

• inferior and superior colliculus

• tegmentum

Tectum (function)

roof of midbrain and some reflexive movements

Inferior and Superior Colliculus (functions)

sensory processing - hearing and vision respectively

Tegmentum (function)

intermediate level + wider range of functions (sleep)

The forebrain is composed of the following:

• the lobes (frontal, occipital, parietal, temporal)

• the fissures (central, lateral)

• subcortical structures (limbic system, cingulate gyrus, basal forebrain, basal ganglia)

• ventricles

• meninges

Frontal lobe (functions)

behavior, emotion, personality, motor cortex

Parietal lobe (functions)

sensory info and sensory cortex

Occipital lobe

vision

Temporal lobe

auditory info and memory encoding

Limbic system components

• amygdala

• hippocampus

• thalamus

• hypothalamus

Amygdala

emotional info

Hippocampus

new memories

Thalamus

working memory + input to cortex

Hypothalamus

direct pituitary gland + homeostasis

Cingulate gyrus (function)

emotion processing + learning/memory

Basal forebrain

• nucleus basalis

• release acetylcholine to cerebral cortex

• linked to arousal

Basal ganglia

movement and skills/habits

Ventricles

• 4

• produce CSF (choroid plexus cells) used as suspension system to aid in swelling

= hydrocephalus- overproduction of CSF leading to learning disabilities

Meninges

• membranes surrounding brain and spinal cord

• 3 of them = pia mater, arachnoid mater, dura mater

• swollen blood vessels responsible for pain of headache

• no pain receptors in the brain

Gray matter

• packed with dendrites/cell bodies

• neurons send axons through white matter to the brain and other parts of spinal cord

White matter

• made up of axons

• connects sections of gray matter

Sensory nerve

• sensory info

• dorsal root ganglia (cell bodies)

Motor nerve

• motor info

• cell bodies inside the spinal cord

Ganglia + nuclei

clusters of neuron in PNS + CNS respectively

Autonomic nervous system

• things you can’t control

• unvoluntary functions (heart and digestive system)

• divided into PARASYMAPTHETIC and SYMPATHETIC divisions

Sympathetic Division

• “fight or flight“

• prep organs for activity burst (increased heart rate // decreased digestive activity)

• sweat, adrenal glands, etc.

• norepinephrine

Parasympathetic Division

• “rest and digest“

• opposite of sympathetic activities (decreased heart rate // increased digestive activities)

• acetylcholine

• many cold remedies have anti-parasympathetic properties (leads to their restriction - anti-runny nose)

Somatic Nervous System

• voluntary nervous system

• skeletal muscles

• sensory nerves

4 categories of research methods

• effects of brain damage

• stimulation of the brain

• recording brain activity

• correlating anatomy with behavior

Effects of brain damage (research)

• Paul Broca = Broca’s Area = language production

• ablation vs. lesion (remove vs. damage)

• stereotaxic instrument: placement of electrodes on animal studies

• “virtual lesion“: transcranial magnetic stimulation - strong

Stimulation of the brain (research)

• Transcranial Magnetic Stimulation - mild

• Optogenetics

- using light to control neurons

- Karl Deisseroth

-released for use in 2009

- required 3 steps

1) protein that responds to light

2) develop a virus as a delivery system

3) develop thin fibers to shine light

Recording Brain activity (research)

electrodes to look at individual neurons

• Electroencephalograph (EEG)

• Magnetoencephalography (MEG)

• Positron-emission tomograph (PET) = inject with radioactive substance

• Functional Magnetic Resonance Imaging (fMRI); tracking blood flow

Correlating anatomy to behavior (research)

• phrenology: using race and skull shape and correlating to behavior(not used anymore)

• Computerized Axial Tomography (AT)

• Magnetic resonance imaging (MRI)

1800s discovery about us

scientists discovered we are made up of cells

Santiago Ramon y Cajal discovery

• used silver salt staining method

• used art to show that nerve cells remain separate and do not grow onto each other

Astrocytes

• star shaped, wrapped around the synapse

• important for rhythms such as breathing

• shield synapse from surrounding chemicals

• dilate vessels to bring nutrients to active areas

• tripartite synapse hypothesis

- chemicals released by the terminal cause astrocytes to release chemicals to magnify/modify message to next neuron

- gliotransmitters

Microglia

• act as part of the immune system

• removes viruses, fungi, dead/damage neurons, weakest synapses

• negative feedback

Oligodendrocytes (CNS) & Schwann Cells (PNS)

• build myelin sheath (insulin layer- provides nutrients to cells)

• provides nutrients

Radial glia

• guide migration during embryonic development

• differentiate after embryonic development

• most will differentiate into astrocytes (in mammals, mostly)

Molecules that cross the blood-brain barrier

• Vitamin A

• Vitamin D

• drugs meant for the brain

Molecules that cannot cross the blood-brain barrier

• glucose

• amino acids

• purines

• iron

• choline

• Vitamin B

• Vitamin C

• Most chemotherapy drugs

Alzheimer’s and Blood-Brain Barrier

blood-brain barrier shrinks and lets in harmful chemicals

Charles Scott Sherrington (research)

discovered evidence of synapse using behavioral studies

• reflexes are slower than conduction along an axon

• several weak stimulus stronger than 1 strong stimuli

• when one set becomes excited, another relaxes

delay between stimulus and reflex

thought neuroscience was largely electrical, rather than chemical

TR Elliot

proposed that the sympathetic system stimulated muscles by releasing hormones

• prevailing belief was solely in electrical impulses

Otto Loewi

demonstrated the effects of neurotransmitters

• Frog Experiment

• stimulated vagus nerve of a frog and taking fluid and placing it around the frog’s heart (slowed down heart rate)

• stimulated accelerator nerve of a frog and took fluid and placed it around the frog’s heart (accelerated heart rate)

• made room for the development of psychiatric drugs!

TYPES OF NEUROTRANSMITTERS: Amino acids

glutamate, GABA, glycine, aspartate

TYPES OF NEUROTRANSMITTERS: Modified Amino Acids

acetylcholine

TYPES OF NEUROTRANSMITTERS: Monoamines

• catecholamines= norepinephrine, epinephrine, dopamine

• indoleamines= serotonin

TYPES OF NEUROTRANSMITTERS: Neuropeptides

endorphins, substance P

TYPES OF NEUROTRANSMITTERS: Purines

ATP, adenosine

TYPES OF NEUROTRANSMITTERS: Gas

nitric oxide

Ionotropic effects

• tend to be excitatory or inhibitory

• SHORT AND QUICK EFFECTS

• Rapid communication, vision, and hearing

• Ex. Glutamate, GABA, glycine, and acetylcholine

Metabotropic effects

• neuromodulators that modulate message to other neurotransmitters

• SLOW TO START, LONGER LASTING

• Taste, emotion

• Ex. dopamine, norepinephrine, serotonin

Neurotransmitters vs. Neuromodulators

Neurotransmitters

• synthesized from axon terminal

• is released from adjacent synaptic knob

• lasts milliseconds

Neuromodulators

• synthesized from cell body, dendrites, sides of axon

• released by spreading out

• lasts seconds to minutes

DRUGS: Hallucinogenic

• LSD, peyote

• resembles receptor (mimics effect of receptor)

• distorts perception / inappropriate timing and longer stimulation

DRUGS: Nicotine

• increases dopamine release

• triggers reward center= more dopamine and wanting more and more

DRUGS: Opiates

• derived from or similar to opium (morphine, heroine, methadone)

• same receptors as endorphins (pain killers)

Serotonin and Catecholamines

• detach from receptor

• reuptake into pre synaptic neuron

DRUGS: Stimulants

• amphetamine, methylphenidate, cocaine

• prevents uptake of serotonin, dopamine, norepinephrine (basis for ADHD meds)

DRUGS: Cannabinoids

• tells presynaptic cell to stop even though it never sent a message in the first place

• decreases exhibitory/inhibitory messages

• can slow reaction time and anxiety

Plato (history)

“sight rays“

• theory is not feasible because it would take a long time for a sight ray to travel to the sun

Hasan Ibn-al-Haytham (history)

• philosopher

• the perception of an object is not in the object itself, but instead in our brain (internal process rather than external process)

Rene Descartes (history)

• philosopher

• nerves sent a pattern of impulses arranged like the image to the brain

Joannes Miiller

Law of Specific Nerve Energies

• modern interpretation: nature of perception is defined by the pathway over which the information travels

• Ex. rubbing your eye and seeing little black dots

• Miillers interpretation: what excites a nerve establishes a special and unique energy

pupil

opening

iris

eye color, muscles

cornea

outer layer

lens

focus light

• ciliary muscle

retina

back of the eye

• receptors

• fovea (location of cones/rods)

optic nerve

runs to the occipital lobe

Visual info processing in the retina

receptors —> bipolar cells —> ganglion/amacrine cells

• receptors are the bottom layer

fovea

• center of the retina

• 1 bipolar cell to 1 cone

• midget ganglion cells

Optic nerve

• bundle of ganglion axons

• blind spot

RECEPTORS: Cones

• color vision

• bright light

• clustered in the fovea

• details!

RECEPTORS: Rods

• located in the periphery of retina

• good in faint light

• motion detection

Photopigments

release chemicals when struck by light

• Ex. Il-cis-retinal (vitamin A derivative), il-trans-retinal, opsins (proteins)

Trichromatic Theory of Cones

• Thomas Young

• Hermann von Helmholtz

• 3 kinds of cones (red/green/blue)

-more red and green

-3 primary color based

Ratio Activity

• relative response rates

• red = long wavelength

• green = middle wavelength

• blue = short wavelength

Opponent-Process Theory

• Ewald Hering

• color perceived in opposites

-red to green, black to white, yellow to blue

-example: bipolar cell with prolonged exposure

• still an issue

-afterimage of a green square with a center white circle is red

Retinex Theory

• need to explain color constancy

-ability to recognize colors in different lightning

-comparisons

-can trick the brain by removing context

• brightness constancy

-brightness perceived as comparison to other objects

• Edwin Land

-the cortex compares info from retina to determine color and brightness

Visual Processing Pathway

receptors (cones/rods) —> horizontal cell (inhibitory contact with bipolar cells) —> bipolar cells —> amacrine cells —> ganglion cells (optic nerve) —> lateral geniculate nucleus —> thalamus/visual cortex

Lateral Inhibition

• emphasizes borders of objects

• bipolar cells

-light decreases inhibitory output (net excitation)

-bipolar cell sends message to horizontal cells

-horizontal cells inhibit nearby bipolar cells

• not limited to vision

• helps explain certain illusions

-Hermann grid

Parvocellular cells

• ganglion cells

• small cell bodies, small receptive fields

• in fovea - color!

Magnocellular cells

• ganglion cells

• larger, larger receptive field

• even distribution

Koniocellular cells

• small cell bodies

• occur throughout retina

• very difficult to study - have a variety of functions

Primary visual cortex

• occipital cortex

-Area V1, striate cortex (striped appearance)

= conscious visual experience

= optical illusions

= “imagining“ seeing = dream, vision

Aphantasia

When you close your eyes and try to picture an object like an apple or a loved one's face, you see nothing instead of a mental picture

Damage to visual cortex

• no conscious vision

• no visual imagery or dreams

• blindsight= ability to respond to visual stimuli without seeing it consciously

Hubel and Wiesal

electrodes to record activity in the occipital cortex of cats and monkeys

Simple cells

• receptive field with fixed excitatory/inhibitory zones

• more light on inhibitory zones, less of a response

• horizontal or vertical

Complex cells

• Areas V1 and V2

• stimuli moving in a particular direction