Lecture 3 [ Notes ].docx

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Published on 15 Apr 2013
School
York University
Department
Psychology
Course
PSYC 1010
Page:
of 4
Cells in the Nervous System
o Neurons
o Basic links that permit communication within the nervous system
o Soma: contains cell nucleus and much of the normal chemical machinery
o Dendrites: specialized to receive information
o Axon: long, thin fibre that transmits signals away from the soma to other neurons or to
muscles or glands
o Myelin sheath: insulating material that encases some axons
o Terminal buttons: small knobs that secrete neurotransmitters
o Synapse: junction where information is transmitted from one neuron to another
o Glia
o Account for over 50% of brain’s volume
o Supply nourishment to neurons, help remove neurons’ waste products, and provide
insolation around many axons
o They also orchestrate the development of the nervous system in the human embryo
o Can also send and receive chemical signals
o Play important role in memory formation and the experience of chronic pain
The Neural Impulse
o All-or-None Law: the action being made has to fully happen or not happen at all. The action
cannot half-happen, just like you can’t half-fire a gun. However, you can change the rate at
which the action happens
Cell-Cell Communication
o Synaptic cleft: microscopic gap between terminal button of one neuron and cell membrane of
the other
o Neurotransmitters: chemicals that transmit information from one neuron to another
o Two kinds of messages sent from cell to cell
o Excitatory PSP: positive voltage shift that increases the likelihood that the postsynaptic
neuron will fire action potentials
o Inhibitory PSP: negative voltage shift that decreases the likelihood that the postsynaptic
neuron will fire action potentials
Integrating Signals: Neural Networks
o Synaptic pruning: key process in the formation of the neural networks that are crucial to
communication in the nervous system
Neurotransmitters and Behaviour
o Acetylcholine
o Found throughout the nervous system
o Only transmitter between motor neurons and voluntary muscles
o Contributes to attention, arousal, and memory
o Agonist: chemical that mimics the action of a neurotransmitter
o Antagonist: chemical that opposes the action of a neurotransmitter
o Monoamines
o Include three neurotransmitters: dopamine, norepinephrine, and serotonin
o Dopamine is used by neurons that control voluntary movements
o Serotonin controls the regulation of sleep and wakefulness and eating behaviour
o GABA and Glutamate (amino acid transmitters)
o GABA
produce only inhibitory postsynaptic potentials
widely distributed in the brain
responsible for the inhibition in the central nervous system
contributes to anxiety in humans
o glutamate
always has excitatory effects
contribution to learning and memory
o Endorphins
o Internally produced chemicals that resemble opiates in structure and effects
o All over the body
o Contribute to modulation of pain
Organization of the Nervous System
Peripheral NS
o Made up of all the nerves that lie outside the brain and spinal cord
o Somatic NS
o Made up of nerves that connect to voluntary skeletal muscles and to sensory receptors
o Require to nerve fibres
Afferent: axons that carry information inward to the central nervous system
from the periphery of the body
Efferent: axons that carry information outward from the central nervous system
to the periphery of the body
o Autonomic NS
o Made up of nerves that connect to the heart, blood vessels, smooth muscles, and glands
o Controls automatic, involuntary, visceral functions
o Two branches:
Sympathetic: branch that mobilizes the body’s resources for emergencies
Parasympathetic: branch that generally conserves bodily resiurces
Central Nervous System
o Consists of the brain and spinal cord
o Cerebrospinal fluid: nourishes the brain and provides a protective cushion for it
o Spinal cord
o Connects the brain to the rest of the body through the peripheral nervous system
o Enclose by meninges and bathed in CSF
o Extension of the brain
o Has many axons that carries the brain’s commands to peripheral nerves and relay
sensations from periphery to brain
o Brain
o Contains billions of interacting cells
o 1.5 kg
Research Methods
o EEG (electroencephalograph): device that monitors the electrical activity of the brain over time
by means of recording electrodes attached to the surface of the scalp
o Lesioning:
o involves destroying a piece of the brain
o Done by inserting an electrode into a brain structure and passing a high-frequency
electric current through it to burn the tissue and disable the structure
o Stereotaxic instrument: device used to implant electrodes at precise locations in the
brain
o ESB (electrical stimulation of the brain)
o Involves sending a weak electric current into a brain structure to stimulate it
o Most of this research is conducted with animals
o Transcranial Magnetic Stimulation
o New technique that permits scientists to temporarily enhance or depress activity in a
specific area of the brain
o Magnetic coil on a small paddle is held over an area of a subject’s head. This creates a
magnetic field that penetrates down 2 cm.
o By varying the timing and duration of the magnetic pulses, a researcher can either
increase or decrease the excitability of neurons in the local tissue
o Brain-imagine Procedures
o CT (Computerized Tomography): computer-enhanced x-ray of brain structure
o PET (position emission tomography): can examine brain function. Radioactively tagged
chemicals are introduced into the brain.
o MRI: (magnetic-resonance image): uses magnetic fields, radio waves, and computerized
enhancement to map out brain structure.
o fMRI: monitors blood flow and oxygen consumption in the brain to identify areas of high activity
The Brain and Behaviour
o Hindbrain

Document Summary

The neural impulse: all-or-none law: the action being made has to fully happen or not happen at all. The action cannot half-happen, just like you can"t half-fire a gun. However, you can change the rate at which the action happens. Inhibitory psp: negative voltage shift that decreases the likelihood that the postsynaptic neuron will fire action potentials. Integrating signals: neural networks: synaptic pruning: key process in the formation of the neural networks that are crucial to communication in the nervous system. Include three neurotransmitters: dopamine, norepinephrine, and serotonin: dopamine is used by neurons that control voluntary movements, serotonin controls the regulation of sleep and wakefulness and eating behaviour, gaba and glutamate (amino acid transmitters, gaba. Widely distributed in the brain responsible for the inhibition in the central nervous system contributes to anxiety in humans: glutamate. Always has excitatory effects contribution to learning and memory: endorphins.