Brain bee all parts

What part of brain is active while taking risks

Insular Cortex communicates with limbic system and memory

What hormones correlate with risk taking and risk aversion

Testosterone: risk-taking

Cortisol: risk-aversion

How many neurons in human brain

86 Billion

Electrical power used by the brain

25 watts

How many different types of neurons in the brain

over 10,000

Neural Rosette

Model of brain grown in petri dish

What do the colors in a neural rosette represent

Red = precursor cells

Green = new cells and glia

What connects the two cerebral hemispheres

Corpus Callosum

Where is the Hippocampus

temporal lobe

Where is the Amygdala

temporal lobe

Basal Ganglia

coordinates movement, center of the brain

Size and neuron count of Cerebellum

Around 10% of brain in volume,

contains over half of the brain's neurons

3 parts of brainstem

Midbrain, Pons, Medulla

What nerve tract connects the left and right temporal lobes

Anterior Commissure

voltage range of brain waves

20-200 μV (alpha and delta)

5-10 μV (beta and theta)

What are columns in the the cerebral cortex

Stacks of neural circuits, each dedicated for a specific task

What percent of brain neurons are excitatory?

80%

Most common type of excitatory neuron

Pyramidal Cell (cone shaped body)

Dendrite organization of pyramidal cells

one set of dendrites at the apex, another smaller set at the base (Apical & Basal)

Glia to neuron ratio in the brain

10:1 (or more)

How does neuron ratio in brain vary?

Some areas in human brain are 1:1, other vary greatly

Ependymal cells

make CSF, have cilia,

Microglia

immune function, phagocytose

Astrocytes

provide nutrients, assist with synaptic formation, make blood brain barrier

Schwann Cells & Oligodendrocytes

myelinate in the PNS/CNS

Resting membrane potential

-70mV

post-synaptic density

region on post-synaptic neuron with many neurotransmitter receptors

What glial cells clean up extra neurotransmitters left at synapse?

Astrocytes

Most common excitatory neurotransmitter in the brain

Glutamate

Most common inhibitory neurotransmitter in the brain

GABA (Gamma-aminobutyric acid)

What percent of excitatory synapses in the brain use Glutamate?

over half

What are the two types of channels GABA binds to

Ionotropic: opens Cl- channels

Metabotropic: opens K+ channels

Tay Sach's Disease

Mutation on chr. 15, Beta-Hexosaminidase A is defective

What sense involve the most activity of cerebral cortex

Vision (uses 30% of cerebral cortex)

Function of the Iris

controls size of pupil (amount of light entering eye)

Organization of retina

Photoreceptors are at the very back, send information forward

How many photoreceptors in each human eye

125 million

What percentage of photoreceptors are rods

95%

What photoreceptors provide more detailed and clear images

Cones

Fovea

center of retina, densely packed cones

What color cone is fovea missing?

Fovea only has green and red cones, no blue cones

Macula

Area surrounding fovea, important for reading and driving

Leading cause of blindness in people over 55

Macular Degeneration

"Donut-hole" inhibition

Shining on the hole stimulates the visual system, while shining on the donut ring inhibits it

Path of optic nerve

Optic nerve --> Optic Chiasm --> LGN (Lateral Geniculate Nucleus) --> Primary Visual Cortex

Layers of the visual cortex

Middle layer preserves retina's visual map well, peripheral layers are more specialized

Dorsal stream of vision

"Where", parietal lobe:

Motion, timing, and response

Ventral stream of vision

"What", temporal lobe:

shape, color, object, memories and experiences

Strabismus

Crossed eyes, bad depth perception

What happens to untreated strabismus

one eye is favored, the other eye slowly loses vision.

If not treated by age 8, blindness becomes permanent

Basilar membrane

Membrane along the center of the Cochlea

Frequency mapping on the Basilar membrane

Higher pitched sounds are close to window

Pathway of Cochlea nerve

Information --> Thalamus --> Auditory cortex

What lobe is the auditory cortex

Temporal Lobe

Which hemisphere is more important for understanding and producing speech

Left hemisphere

What are the only sensory neurons to continually replace throughout life

Olfactory neurons

Do taste buds regularly regenerate

Are taste buds neurons?

Yes

No

How many taste buds does a human have

5 to 10 thousand

How many taste cells are in each taste bud

50 to 100

By what age do we start losing taste buds

age 50

Which three cranial nerves send information of taste

Facial, Glossopharyngeal, Vagus

Pathway of taste

Taste buds --> thalamus --> gustatory cortex

Where is the Gustatory Cortex

Bottom of Frontal Lobe

Pathway of smell

Olfactory cells (nasal cavity) --> Olfactory bulbs (bottom of frontal cortex) --> olfactory cortex

Where is the Olfactory Cortex

upper temporal lobe

how many different types of olfactory cells do humans have

around 1,000

What is the only sense to skip the thalamus

Smell

Two point discrimination

measures perception acuity. More densely nerve packed areas can distinguish between closer stimuli

What enhances the sensitivity of receptors to tissue damage

Prostaglandins

Allodynia

extreme sensitivity, pain resulting from even soft touch

Neuropathic Pain

pain in the absence of stimuli

What does Diabetic Neuropathy do to nerves

Nerves in areas exposed to high blood sugar send random signals of tingling or aching

A-beta fibers

Large diameter, thick myelination

Typical touch stimuli

A-delta fibers

Small diameter, thin myelination

"Fast" painful stimuli

C fibers

smallest diameter, no myelination

slow, dull pain

Actions of Periaqueductal Gray

receives pain info from cortex, modulate pain via descending pathways, release endorphins

Flexors

Muscles that bend a joint

Extensors

Muscles that straighten a joint

Myotatic reflex

Stretch reflex, stretched tendons stimulate extensor muscles

flexion withdrawal reflex

withdrawal of leg from painful stimuli

flexion crossed extension reflex

Other non injured leg stimulates extensors too stay put and maintain balance

Gamma Motor neurons

keep muscle spindles taut

Muscle Spindles

detect magnitude and speed of muscle stretch

Golgi Tendon Organs

located at muscle-tendon connections, detect tension

Where are neuronal circuits activated

Central pattern generators in the spinal cord and brainstem

Motor Cortex

very back of Frontal Lobe

Where are cell bodies of motor neurons located?

Ventral horn of Spinal Cord

Two pathways of Basal Ganglia

facilitates desired motor program, and inhibits unwanted motor program

Regions that assist with motor control

Cerebellum, Basal Ganglia, Thalamus, Midbrain & brainstem

Substantia Nigra

Sends signals to Basal Ganglia with Dopamine.

Where is the Substantia Nigra

high up the brainstem, upper midbrain, below Basal Ganglia

Huntington's vs Parkinson's Disease symptoms

Parkinson's has slowness, tremors, rigidity, akinesia

Huntington's has jerking and twitching (chorea), especially face and extremities

Where is Basal Ganglia

above the brainstem, deep within the cerebrum

Damaged regions in Parkinson's disease

loss of Dopaminergic neurons in Substantia Nigra

Damaged regions in Huntington's Disease

loss of inhibitory (GABA) neurons in the Basal Ganglia which suppress random movements

Cerebellum function

fine-tuning motor skills (timing and accuracy)

adaptability to changing body or situations

Motor learning (muscle memory)

Intention tremors

Common in Cerebellar diseases, tremors only when trying to move

What is linked to cerebellar disease?

Chronic alcohol abuse

Famous patient for studying memory

Patient HM (Henry Molaison)

What part of the brain was removed in Patient HM

Both hippocampi