Neuroanatomy of the Brain

Brain Stem

• controls basic functioning (evolutionarily the oldest part, so most living creatures have it)

• made up of

  • medulla

  • pons (+ reticular formation)

Medulla

controls heartbeat, lungs, digestion

pons

bridges brain and spinal cord

bridges 2 hemispheres of cerebellum

helps with coordination/symmetry

reticular formation

a region in the pons

controls alertness

is a neural network

responsible for sleep/wake cycles

works w/melatonin and circadian rhythm

Cerebellum

balance, coordination, movement

plays role in:

• classical conditioning memory

• procedural memory

Thalamus

structure in the midbrain

• like a router, sorts and sends data

• first place where all the senses are processed EXCEPT for smell

• then relays to rest of the brain

• links brain stem and cortex

limbic system

“the emotional center”

composed of:

• hippocampus

• amygdala

• hypothalamus

Hippocampus

in the limbic system

• processes everyday new memories

Amygdala

brain region in limbic system

threat detection

processes negative emotions (anger, fear, etc.)

Hypothalamus

in the limbic system

• homeostasis (circadian rhythm, hunger)

• 5 Fs: Freeze, flight, fight, feed, fuck

• works with the pituitary gland

basal ganglia

a subcortical structure

helps with motor control (works with acetylcholine)

if damaged, causes shaking

Nucleus Accumbens

brain region part of the reward system

lights up when pleasurable activity

Cerebral cortex

the outermost layer of brain

like 85% of brain

where you process all the senses (thalamus reroutes stimuli to here)

lots of wrinkles = more surface area

composed of 4 lobes

Frontal Lobe

one of the four lobes

• contains

  • pre-frontal cortex

  • motor cortex

  • Broca’s area

motor cortex

in frontal lobe

= voluntary movement

Pre-frontal cortex

in frontal lobe

= executive functioning (prospective thinking. helps understand cause and effect, multiple directions)

• abstract reasoning

• decision-making/judgement

• personality

Broca’s area

in frontal lobe (LEFT)

= language production

• helps to make sense of language, make coherent sentences

• writing and speaking

if damaged: can only say one or two words (but others can understand what you mean)

Parietal Lobe

one of the four lobes

= touch

somatosensory cortex

in parietal lobe

= processes touch (pain, pressure, and temp)

= proprioception (where you are in space)

Homunculus

= map that shows proportions of somatosensory cortex

• the more space, the more sensitive

  • ex. big face = more nerves in the face that connect to somatosensory cortex

Occipital Lobe

one of the four lobes

= vision

visual cortex

in occipital lobe

= color, object recognition

optical nerve runs all the way from eye to this cortex

Temporal Lobe

one of the four lobes

= near temples

= hearing

auditory cortex

in temporal lobe

= processes hearing

Wernicke’s Area

an association area in the left temporal lobe

= language understanding (need language production first)

if damaged: incoherent gibberish, but fluent

Broca and Wernicke

these two did autopsy to to discover language areas (1870s)

Corpus Callosum

band of fibers that connects right and left hemispheres of the cortex

just like how pons is bridge for cerebellum, __ ___ is bridge for hemispheres

does left and right brained-ness exist?

no, one hemisphere can’t be more dominant than the other for a person

however, for everyone, different functions are localized in a MAJORITY of one side

where is language mainly processed?

left hemisphere

Left Hemisphere

hemisphere that does sequential processing (step-by-step)

• language functioning (speaking, writing, reading)

• analytical (math)

Right Hemisphere

hemisphere that does holistic processing (big-picture)

• art/music/facial recognition

• irony/sarcasm

• spatial reasoning (rotating object in head)

• processed in right brain

you know it is a triangle, but you can’t recall the word

(can draw it)

If corpus callosum is cut and you see triangle in left vision,

• processed in left brain

language = can identify and say “circle!”

If corpus callosum is cut and you see circle in right vision,

Pituitary gland

Controlled by hypothalamus, releases different hormones and triggers other glands to release hormones

Pineal gland

Regulates circadian rhythm by releasing melatonin

Parietal lobe

Input from multiple senses, touch and pain, spacial and mathematical reasoning

Dendrites

Receive messages from other cells

Cell body

Cell-s life-support center

Axon

Passes messages away from the cell body to other neurons, muscles, or glands

Neural impulse

Electrical signal traveling down the axon

Myelin sheath

Covers the axon and speeds up neural impulses

Neurons that FIRE together…

WIRE together

There is a biological event for…

Every psychological event, but not vice versa

Union of opposites

The body is characterized by opposing tendencies

When does the brain process most information?

Outside of our awareness

Axon terminal

The place at the end of the axon where neurotransmitters are released

Terminal button

Knobs at the end of the neuron that release the neurotransmitters

Action potential

The electrical impulse that is sent

Resting potential

The voltage across a neuron that is at rest

Selectively permeable

It does not allow most things in so the environment is sustained

Depolarization

When positive sodium comes into the axon

Repolarization

When negative potassium is released into the axon

Hyperpolarization

When the potassium is greater than the sodium in the axon for a bit before it returns to normal

Refractory period

The time between action potentials when the neuron can’t fire

Excitatory signals

Signals that cause the neuron to fire

Inhibitory signals

Signals that cause the neuron to notstop firing

Threshold

The amount of excitatory signals greater than inhibitory needed to fire an action potential

All-or-none response

No matter the intensity of the signal, the neuron will either fire with the same intensity or not.

Agonist

Help neurotransmitters by binding to receptors to produce a response

Antagonist

Block the effects of neurotransmitters by binding but not producing a response

Synapse

The place where neurotransmitters are released

Neurotransmitter

Chemical messengers that send messages across the synaptic gap

Reuptake

When neurotransmitters are taken up again by the synapse

Somatic

Voluntary muscular systems; sensory and motor neurons

Autonomic

Involuntary processes; sympathetic and parasympathetic

Interneurons

Connect motor and sensory neurons

EEG

Measures electrical activity of the brain

CT

Assesses brain for injuries or brain conditions

PET

Shows where there is more or less activity in the brain

MRI

Shows a physical picture of the brain

fMRI

Shows changes in blood flow in the brain

Glial cells

Maintain and support neurons chemically or physically (ex: schwann cells, which create the myelin sheath)

Plasticity

Brain can easily adapt to new circumstances via pruning and proliferation

Depressants

Alcohol, barbiturates, opiates

Stimulants

Amphetamines, cocaine, ecstasy

Hallucinogens

LSD, marijuana