COGS 17 Handout 1 Pg. 1

Chapter 1

  1. What are the two main beliefs about the Mind-Body question?

Dualism / Monism
Main ideas: mind and body are two separate entities / Main ideas: mind and body are interconnected
Supporting evidence:
Descartes (though hypothesis incorrect) / Supporting evidence:
Blindsight
Hemi-neglect
Split brain
  1. What is the difference between bottom-up processing and top-down processing?
  1. Match the following scientists with their respective ideas. Names can be used more than once.

  1. Descartes
  2. Galvani
  3. Bell-Magendi
  4. Ramon y Cajal
  5. Mueller
  6. Darwin
/ _A_ First testable hypothesis for MB question
_D_ Neuron Doctrine (neurons are independent)
_C_ Doctrine of Specific Nerve Energies (signals from different sensory areas travel in different input lines to specialized areas of the brain)
_E_ The brain is specialized into the sensorium and the motorium
_B_ Proposed that our animating force is caused by electricity
_F_ Natural Selection
_A_ Proposed that the pineal gland is where the mind and brain come together

Chapter 2

  1. Label the parts to the neuron (assume in PNS) and describe the function of each part. (dendrites, nucleus, cell body, axon, myelin sheath, terminal buttons, nodes of ranvier, synapse)

2. Describe the following terminology:

mitochondria dendritic spines (head vs. neck) anterograde transport

cytoskeletonprotein retrograde transport

DNARNA

3. Setting the stage for Action Potentials

  1. Resting Potential ( __-70___ mV) Question: Why is it like this?
  1. Ion concentrations

Ion / Extracellular concentration (high or low) / Intracellular concentration (high or low)
Sodium (Na+) / high / low
Potassium (K+) / low / high
Chloride (Cl-) / high / low
Anion (A-) / none because impermeable / high

ii. Two forces (Nature wants balance)

-Concentration Gradient/Diffusion: molecules in area of greater concentration will diffuse to an area of lesser concentration

-Electrical/Electrostatic Gradient: positively charged particles will move away from other positive and towards negative

-Label intra/extracellular space & the ion’s desired directionof movement

iii. If these forces are at work, what’s stopping the concentrations/electric gradient from equalizing?

-Pumps: Sodium Potassium Pump

-pump continuously pushes 3 Na+ out and 2 K+ in, needs ATP

-membrane is not permeable to Na+ so it’s hard to pass through other than through the channels

-Channels:

-voltage gated/dependent channels: channels whose opening and closing depends on different voltages

iv. Depolarization (EPSP) vs. Hyperpolarization (IPSP)

-depolarization: the voltage increases to become less negative. EPSP (excitatory post synaptic potential)

-hyperpolarization: the voltage decreases to become more negative, moving further away from the threshold potential. IPSP (inhibitory post synaptic potential)

  1. The Action Potential
  2. First the bigger picture:

  1. Where does AP begin? Axon hillock
  2. Advantages of myelin:

-reduces the number of ion channels

-reduces the number of Na+/K+ pumps

-increases speed of conduction

-reduces energy needs

  1. Where does AP regenerate? Nodes of Ranvier

-Nodes of Ranvier contain the voltage gated Na+/K+ channels that are needed for an AP to occur

  1. Why does it need to regenerate?

-Over distance/time the signal weakens. In order for the signal to be transported all the way to the terminal buttons, it needs to be regenerated

  1. Graded potentials vs. Action potentials

Graded
-Small changes in voltage/chemical distribution
-conducted passively
-lose energy as they travel down the dendrite/axon / Action Potentials
-Large changes in voltage/chemical distribution that communicate information from one neuron to another
-Follows all or nothing law (given a cell, an AP always has the same amplitude regardless of the intensity of the stimulus that triggered it)
-only fires when threshold potential is reached
  1. Mapping the electrical change (zoomed into the node of Ranvier)
  1. Cell is at resting potential (-70 mV)
  2. Graded potentials occur but if they don’t reach the threshold potential (-55 mV)
  3. Once the electrical potential reaches threshold, Na+ voltage-gated channels open. Na+ floods in due to the forces of diffusion AND electrostatic pressure
  4. As previous Na+ gates close (due to it becoming refractory and blocked), K+ channels begin to open. K+ channels open later because they require a greater level of depolarization. K+ flows out because of diffusion and electrostatic pressure. This causes the inside of the cell to hyperpolarize or repolarization.
  5. As K+ ions leave the cell, the membrane potential gradually returns to -70mV
  6. The extra K+ ions outside the membrane are responsible for the extra hyperpolarization.
  1. Communication between neurons
  2. Synapses:
  3. Three types:
  4. axodendritic (synapses on the dendrite or dendritic spine)
  5. axosomatic (synapses on the soma)
  6. axoaxonic (synapses on the axon)
  1. Label and describe the following (electrical signal[x2], terminal button, vesicles, receptors, presynaptic neuron, postsynaptic neuron, synaptic cleft, Ca++)

  1. Receptors
  2. 2 types [there is a great figure on pg. 59 in the textbook that visually explains this]

1. ionotropic: receptor is on an ion channel which opens immediately

2. metabotropic: receptor triggers cascade of events, eventually opening ion channel

a) ion channel is opened directly by the α subunit of an activated G protein

a. molecule of transmitter substance binds with receptors

b. receptor activates G protein

c. α subunit breaks away, binds with ion channel then opens it

d. ions enter cell produce post synaptic potential

b) the α subunit activates an enzyme, which produces a 2nd messenger that opens ion channel

a. follows first two steps of above

b. α subunit breaks away, activates enzyme, which produces 2nd messenger

c. ion channel opens, ions enter cell and produce post synaptic potential

d. What happens to the NT in the synaptic cleft?

-Post synaptic potentials usually occur very quickly. Terminated by

a) enzymes

b) reuptake (transporters located in the presynaptic membrane remove NT)