ch 2_3 final.ppt - psychology 3801 behavioral neuroscience

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.

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

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

Glial Cells

Myelin producersOligodendrocytes (CNS)Schwann cells (PNS)

Astrocytes – largest glia, many functions

Microglia – involved in response to injury or disease

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



Nissl stain (1880s)Selectively stains cell bodies


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


Directions in the Vertebrate NS

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


Mesencephalon Tectum (dorsal surface)

Inferior colliculi – auditionSuperior colliculi - vision

Tegmentum (ventral) 3 ‘colorful’ structures

Periaqueductal grayo analgesia

Substantia nigrao sensorimotor

Red nucleuso sensorimotor


DiencephalonThalamus – sensory

relay nucleiLGN

Hypothalamus Regulation of motivated

behaviors Controls hormone release

by the pituitary

TelencephalonCerebral cortexLimbic systemBasal ganglia


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

ch 2_3 final.ppt - psychology 3801 behavioral neuroscience

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