COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.
description
Transcript of COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.
![Page 1: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/1.jpg)
COGNITIVE SCIENCE 17
The Electric Brain
Part 1 Jaime A. Pineda, Ph.D.
![Page 2: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/2.jpg)
INPUT
INTEGRATION
OUTPUT
Law of Dynamic Polarization Dendrites generally receive synaptic input (i.e. are postsynaptic) and axons generally send synaptic output (i.e., are presynaptic)
![Page 3: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/3.jpg)
Resting Membrane Potential (Vm) is ~ -70 mV in mammals
Vm is the voltage difference between the inside and outside of the cell
![Page 4: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/4.jpg)
50 440
400 20
40 560
many few
Different concentrations of ions inside and outside the cell
![Page 5: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/5.jpg)
Unequal distribution of ions across cellmembrane creates two major forces
osmotic pressure
electrostatic pressure
![Page 6: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/6.jpg)
Other important factors
- Specific protein channels- Na+, K+, Cl-, Ca++
- Selective permeability of channels- leaky channels- K+ > Cl- > Na+
- Sodium-potassium pump
![Page 7: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/7.jpg)
Na+ / K+ Pump
Restores equilibrium
![Page 8: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/8.jpg)
Graded and Action Potentials•Graded
–Are small changes in membrane potential
–Are conducted passively
–Lose energy as they travel down dendrite/axon
•Action
–Are large changes in membrane potential
–Are conducted actively (regenerated)
–Do not lose energy as they travel down the axon
![Page 9: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/9.jpg)
Graded Potentials
• Depolarization (EPSP)– Vm becomes more positive (Na+ flows in) and
the neuron is more likely to produce an action potential
• Hyperpolarization (IPSP)– Vm becomes more negative (K+ flows out) and
the neuron is less like to produce an action potential
![Page 10: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/10.jpg)
Graded Potentials
• AM signals
• Degrade with distance (decremental conduction)
• Short distance
signaling V
Distance from source
![Page 11: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/11.jpg)
Action Potentials
• FM signals
• Do not degrade with distance (non decremental conduction)
• Long distance signaling
![Page 12: COGNITIVE SCIENCE 17 The Electric Brain Part 1 Jaime A. Pineda, Ph.D.](https://reader035.fdocuments.us/reader035/viewer/2022062409/5681492b550346895db666c0/html5/thumbnails/12.jpg)
Phases of the Action Potential
Firing threshold is the point at which the number ofactivated Na+ channels > inactivated Na+ channels
Absolute refractory period
Relative refractory period