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Psychology 3801Behavioral Neuroscience
Jacqueline Blundell, PhD
2.3
Chapter 2Fundamental Genetics
Basic GeneticsPhenotype – an organisms observable traitsGenotype – the traits that an organism can pass
on to its offspring through its genetic material
Basic Genetics
Genes - basic unit of heredity in a living organismGenes are located on chromosomes
Threadlike structures in the nucleus of each cellChromosomes occur in matched pairsEach species has a characteristic number of pairs of
chromosomes in each body cellHumans?
The two genes (alleles) that control each trait are situated at the same locus, one on each chromosome of a particular pair.
Copyright © 2006 by Allyn and Bacon
Basic Genetics: Cell DivisionMeiosis (Fig. 2.17) – the process of cell division that
produces gametes (egg cells or sperm cells) Chromosomes divide, and one chromosome of each
pair goes to each of the 2 gametes that results from divisionEach gamete has only half the usual number of
chromosomesEgg meets sperm – full number (zygote)
Mitosis – all other cell divisionJust prior to mitosis, the number of chromosomes
double so that when the division occurs, both daughter cells have full number of chromosomes
Basic GeneticsEach chromosome is a double-stranded
molecule of DNAMade up of 4 nucleotide bases
Adenine Thymine guaninecytosine
Adenine-ThymineGuanine-Cytosine
The 2 strands that compose each chromosome are exact complements of each other
Basic GeneticsReplication (Figure 2.20)2 strands of DNA unwindExposed nucleotide bases on each of the 2 strands
attract loose complementary bases from the fluid of the nucleus
2 double-stranded DNA molecules, identical to original
Duplication errors???disease
Mutations – accidental alterations in individual genes
Basic GeneticsSex Chromosomes and Sex-linked Traits
Sex chromosomes may not be matched pairs2 types of sex chromosomes – carry different genes
XY
Female mammals have 2 X chromosomesMale mammals have X and Y chromosomesSex-linked traits – traits that are influenced by genes on the
sex chromosomesMostly controlled by X chromosomeY chromosome – small, few genes
If trait is dominant – occurs more in females or males???If trait is recessive – occurs more in females or males???
Basic GeneticsThe Genetic Code and Gene Expression
Several different kinds of genesStructural genes – contain information for the synthesis of a protein
Proteins – long chains of AA’sControl cellular activity
All cells of the body contain exactly the same structural genesOperator genes – control structural genes (gene expression)
Function to determine whether each of its structural genes initiates the synthesis of a protein and at what rate
Switches On – and turned up, down or offOff – turned on DNA-binding proteins
* Major mechanism by which experience can interact with genes to influence development
The Systems, Structures, and Cells that Make Up Your Nervous System
Chapter 3The Anatomy of the Nervous
System
General Layout of the Nervous System
Central Nervous System (CNS)Brain (in the skull)Spinal Cord (in the spine)
Peripheral Nervous System (PNS)Located outside of the skull and spineServes to bring information into the CNS and
carry signals out of the CNS
Copyright © 2006 by Allyn and Bacon
Protecting the CNSMeninges, Ventricles, and CSF
CNS - encased in bone and covered by three meningesDura mater - tough outer
membraneArachnoid membrane - weblikePia mater - adheres to CNS
surface Cerebrospinal fluid (CSF)
Fluid serves as a cushion
Protecting the Brain
Physical protectionSkull MeningesCerebrospinal fluid (CSF)
Chemical protectionThe blood-brain barrier – tightly-packed
cells of blood vessel walls prevent entry of many molecules
Cells of the Nervous SystemNeurons
MultipolarUnipolarBipolarInterneurons
Glial cellsVarious typesProvide a wide variety of supportive
functions
Copyright © 2006 by Allyn and Bacon
Copyright © 2006 by Allyn and Bacon
Copyright © 2006 by Allyn and Bacon
Glial Cells
Myelin producersOligodendrocytes (CNS)Schwann cells (PNS)
Astrocytes – largest glia, many functions
Microglia – involved in response to injury or disease
Copyright © 2006 by Allyn and Bacon
Terminology Note
CNS PNSMyelin-providing glia
Oligodendrocytes Schwann Cells
Clusters of cell bodies
Nuclei (singular nucleus)
Ganglia(singular ganglion)
Bundles of axons
Tracts Nerves
Neuroanatomical Techniques
Golgi stain (1870s)Visualization of individual neurons
Neuroanatomical Techniques
Copyright © 2006 by Allyn and Bacon
Nissl stain (1880s)Selectively stains cell bodies
Neuroanatomical Techniques
Electron MicroscopyProvides details of neuronal structure Coat slices of neural tissue with an
electron-absorbing substance that is taken up by different parts of neurons to different degrees, then pass a beam of electrons through the tissue onto a photographic film
Neuroanatomical Tracing Techniques
Anterograde (forward)tracing where axons project to
Retrograde (backward)tracing where axons are projecting
from
Copyright © 2006 by Allyn and Bacon
Directions in the Vertebrate NS
Directions in the Vertebrate NS
Copyright © 2006 by Allyn and Bacon
The Spinal CordGray matter – inner component – primarily
cell bodiesWhite matter – outer – mainly myelinated
axonsDorsal – afferent, sensoryVentral – efferent, motor
The Five Major Divisions of the Brain
Figure 3.30
Major Structures of the Brain
Myelencephalon = medullaComposed largely of tractsOrigin of the reticular formation
Arousal
MetencephalonMany tractsPons – ventral surface
Arousal, respiration, etc
Cerebellum - coordination
Major Structures of the Brain
Mesencephalon Tectum (dorsal surface)
Inferior colliculi – auditionSuperior colliculi - vision
Tegmentum (ventral) 3 ‘colorful’ structures
Periaqueductal grayo analgesia
Substantia nigrao sensorimotor
Red nucleuso sensorimotor
Major Structures of the Brain
DiencephalonThalamus – sensory
relay nucleiLGN
Hypothalamus Regulation of motivated
behaviors Controls hormone release
by the pituitary
TelencephalonCerebral cortexLimbic systemBasal ganglia
Major Structures of the Brain
Copyright © 2009 Allyn & Bacon
4 Lobes•Occipital lobes
• vision
•Parietal lobes• Attention• Sensation
•Temporal lobes• Hearing and language• Complex visual patterns• Memory
•Frontal lobes• Motor function• Complex cognitive function
Telencephalon – Subcortical structuresLimbic system – regulation of motivated
behaviorsMammillary bodies, hippocampus, amygdala, fornix,
cingulate, septum
Telencephalon – Subcortical structures
Basal ganglia motor system – voluntary movementsAmygdala, striatum (caudate nucleus + putamen),
globus pallidus
Copyright © 2009 Allyn & Bacon
Summary of major brain structures