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Chapter 2

Chapter 2

5 Pages
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Department
Psychology
Course Code
PSY270H1
Professor
Christine Burton

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Chapter 2 – From Neuron to Brain: Organization of the Nervous System
Nervous system is basis for our ability to perceive, adapt to and interact with the world around us – we perceive,
process and then respond to information from the environment
Neural Structure and Function
Neurons – individual cells in the nervous system, transmit electrical signals from one location to another in the
nervous system
oGreatest concentration of neurons is in the neocortex of the brain – associated with complex cognition
(~100, 000 neurons per cubic mm)
oNeurons have 4 basic parts:
Soma (cell body) – contains nucleus of the cell, control/life centre
Dendrite – branches that RECEIVE information from other neurons
Axon – single axon, long thing tube that TRANSMIT electrical signals to the terminus (end)
where signal can be transmitted to other neurons
2 basic axons – myelinated or not myelinated, myelin – fatty substance that surround some
axons – helps insulate and protect them from interference, also speeds up the conduction of
information
oMyelin is not distributed evenly/continuously, it is broken into segments AKA
Nodes of Ranvier – small gaps in myelin serve to increase conduction speed even
more
Multiple sclerosis – degeneration of myelin sheaths along axons – impairment in balance
and corrdination
Terminal button - small knobs at the end of axons (they do not touch the dendrite of next
neuron), there is a small gap = synapse
oSignal transmission between neurons occurs when the terminal button release neurotransmitters at the
synapse, neurotransmitters – chemical messengers for transmission of information
3 types of chemical substances involved in neurotransmission:
Monoamine neurotransmitters
Amino-acid neurotransmitters
Neuropeptides
** PAGE 38 for chart!!!
Acetylcholine – associated with memory functions, loss of acetylcholine with Alzheimer’s
has been linked to memory impairment
oAlso play a role in sleep and arousal, when someone is awake – increase the activity
of cholinergic neurons in the basal forebrain and the brainstem
Dopamine – associated with attention and learning
oInvolved with motivation process (rewards & reinforcement)
oSchizo – high levels of dopamine, therefore use dopamine inhibitors
oParkinsons – low levels of dopamine
Serotonin – role in eating behaviour and body-weight regulation
oAlso involved in aggression and regulation of impulsivity (drug that block serotonin
will increase aggression)
oAnorexia – high levels of serotonin (= loss of appetite)
Receptors and Drugs
Receptors in the brain that normally are occupied by the standard neurotransmitters can be influenced by drugs
When people stop using drugs, withdrawal symptoms may arise (narcotic dependence) – the form of treatment
differs for acute toxicity (damage done from particular overdose) vs. chronic toxicity (damage done by long term
drug addiction)
www.notesolution.com
Acute toxicity = Naloxone or other related drugs, they occupy the opiate receptors in the brain – thus blocks all
effects of narcotics – binds to receptors and does not activate them
Methadone = narcotic detoxification, binds to receptors and reduce heroin cravings
Viewing Structures of the Brain
In vivo – “livingor postmortemafter death”
Postmortem studies – dissect a brain after person died, examines lesions (i.e. Brocas patient Tan – had speech
problem, problem linked to leison in frontal lobe not called Brocas area - involved with speech production )
Animal Studies single-cell recording, record activity of a single neuron in the brain (insert electrode and
measure changes in electrical activity)
oOther techniques, selective lesioning – surgically removing or damaging part of the brain to observe
resulting functional deficits
Electrical Recordings
Event Related Potentials
oRecord electrical activity in brain – activity appears as waves of various widths (frequencies) and heights (intensities)
oElectroencephalograms (EEGs) – recordings of the electrical frequencies and intensities of the living brain, recorded over
long periods
Through EEGs we can study brainwave activity indicative of changing mental states such as deep sleep or dreaming
Electrode placed on scalp, therefore information not well localized to specific cells – rather detects
changes over time
EEgs can be averaged to reveal:
oEvent-related potentials – record of a small change in the brains electrical activity in response to a
stimulating event
oERPs provide info. About the time-course of task-related brain activity
Static Imaging Techniques
Still images to reveal the structures of the brain, these techniques include – angiograms, computed tomography
(CT) scans, and magnetic resonance imaging (MRI) scans.
The X-ray based techniques (angiogram and CT scan) allow for the observation of large abnormalities of the brain
(i.e. stroke, tumors)
oHowever limited to their resolution and hard to see smaller lesions
MRI – reveals high resolution images of the structure of the brain by computing and analyzing magnetic changes
in energy of the molecules in the body
oElectromagnetic changes are detected by computer and produce a 3D image of brain
Metabolic Imaging
Metabolic imaging techniques rely on changes that take place within the brain as a result of increased
consumption of glucose and oxygen in active areas
An area specifically required by one task are more active during that task compared to general processes,
therefore more oxygen and glucose is consumed in that area.
Positron Emission Tomography (PET) – measure increases in oxygen consumption in active brain area during
information processing – participant given mild does of radioactive form of oxygen (they emit positrons as they
are being metabolized), computer scan brain to produce image
oPET not highly precise, require minimum of half a minute to produce data regarding glucose consumption
– brain is active, always changing – therefore computer avg results = less precise
Functional Magnetic Resonance Imaging (fMRI) – use magnetic fields to construct a detailed 3D image of the
brain in a given moment, uses oxygen consumption to construct image, similar to PET but DOES NOT require
radioactive particleswww.notesolution.com

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Description
Chapter 2 From Neuron to Brain: Organization of the Nervous System Nervous system is basis for our ability to perceive, adapt to and interact with the world around us we perceive, process and then respond to information from the environment Neural Structure and Function Neurons individual cells in the nervous system, transmit electrical signals from one location to another in the nervous system o Greatest concentration of neurons is in the neocortex of the brain associated with complex cognition (~100, 000 neurons per cubic mm) o Neurons have 4 basic parts: Soma (cell body) contains nucleus of the cell, controllife centre Dendrite branches that RECEIVE information from other neurons Axon single axon, long thing tube that TRANSMIT electrical signals to the terminus (end) where signal can be transmitted to other neurons 2 basic axons myelinated or not myelinated, myelin fatty substance that surround some axons helps insulate and protect them from interference, also speeds up the conduction of information o Myelin is not distributed evenlycontinuously, it is broken into segments AKA Nodes of Ranvier small gaps in myelin serve to increase conduction speed even more Multiple sclerosis degeneration of myelin sheaths along axons impairment in balance and corrdination Terminal button - small knobs at the end of axons (they do not touch the dendrite of next neuron), there is a small gap = synapse o Signal transmission between neurons occurs when the terminal button release neurotransmitters at the synapse, neurotransmitters chemical messengers for transmission of information 3 types of chemical substances involved in neurotransmission: Monoamine neurotransmitters Amino-acid neurotransmitters Neuropeptides ** PAGE 38 for chart!!! Acetylcholine associated with memory functions, loss of acetylcholine with Alzheimers has been linked to memory impairment o Also play a role in sleep and arousal, when someone is awake increase the activity of cholinergic neurons in the basal forebrain and the brainstem Dopamine associated with attention and learning o Involved with motivation process (rewards & reinforcement) o Schizo high levels of dopamine, therefore use dopamine inhibitors o Parkinsons low levels of dopamine Serotonin role in eating behaviour and body-weight regulation o Also involved in aggression and regulation of impulsivity (drug that block serotonin will increase aggression) o Anorexia high levels of serotonin (= loss of appetite) Receptors and Drugs Receptors in the brain that normally are occupied by the standard neurotransmitters can be influenced by drugs When people stop using drugs, withdrawal symptoms may arise (narcotic dependence) the form of treatment differs for acute toxicity (damage done from particular overdose) vs. chronic toxicity (damage done by long term drug addiction) www.notesolution.com
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