Biological Foundation of Behavior

8/6/2019 Biological Foundation of Behavior

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Behavioral Neuroscience

Chapter2


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Biology and Behavior

The term behavioral neuroscience describes the

work of scientists from several disciplines who

work to understand how the nervous system is

related to behavior.

Concerned with:

Sensing

Processing

Responding


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The Evolutionary Perspective

The evolutionary

perspective > role of

physiological

structures &behaviors;

adaptation to the

environment


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Natural Selection

Natural selection =

the most fit organisms

survive; they adaptbest to the

environment; pass on

genes


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The Nervous System

We use the processes of sensing,

processing, and responding to interact

with the environment. The nervous system is divided into two

parts:

central nervous system (CNS-brain and spinal

cord)

peripheral nervous system (PNS-all parts of

the nervous system outside the CNS)


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The CNS

The spinal cord is

composed ofsensory

(afferent or ascending)and motor(efferent or

descending) nerves.

Interneurons may

connect sensory andmotor neurons.


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CNS Nerves


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CNS Nerves

A reflex arc occurs in less than 1/1000 of a second

A typical fast response that uses brain pathways takes

about 1/10th of a second


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CNS NervesThe Cranial Nerves

Olfactory

Optic

Oculomotor

TrochlearTrigeminal

Abducens

Facial

Auditory-vestibular

GlossopharyngealVagus

Spinal Accessory

Hypoglossal


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The PNS

PNS > the somatic division and the autonomic

division.

Somatic division > sensory nerves run from

receptors to the brain; motor nerves run to theglands and muscles.

Autonomic division > sympathetic division, which

mobilizes body's resources, and theparasympathetic division which returns body to

homeostasis.


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Divisions of the Nervous System

Central NervousSystem Brain

Spinal cord

Peripheral Nervous SystemSomatic

Autonomic


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Neurons: The Basic Cells

The cells that make up the nervoussystem are called neurons.

Neurons are composed of:

dendrites > receive signals fromadjacent neurons

cell body orsoma

axon > transmits signals terminal buttons > contain

neurotransmitters.


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Structure of a Neuron


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Structure of a Neuron

Bipolar > interneurons or association

neurons

Unipolar > usually sensory neurons

Multipolar > tend to be motor neurons

All neuronscarryimpulsesinonly

onedirection


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The Synapse


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Key Neurotransmitters

Acetylcholine (ACh)

Dopamine

Serotonin Endorphins

Norepinephrine

Gamma amino butryic acid (GABA)


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Refractory Period

Neurotransmitters must be removed from

the synapse before another signal can be

transmitted.

Removal is

accomplished either

by breakdown or byreuptake.


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Agonists and Antagonists

Agonists > drugs that promote the action of a

neurotransmitter.

Antagonists > drugs that inhibit the action of a

neurotransmitter.


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Neuromodulators

Neuromodulators have more widespread

and indirect effects than neurotransmitters.

Neuromodulators also influencetransmission between cells.


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The Action Potential

The reversal in electrical charge is

known as the action potential.


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The Brain: A Closer Look

Phrenology is nota science.Popularized in the

1800s by FranzJoseph Gall

Gall > skills andcharacteristicsdetermined byiding bumps onthe skull.


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Early studies

stimulated or

removed portions

of the cortex.


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The Brain

The brain is divided

into the hindbrain, the

midbrain, and the

forebrain.


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The Hindbrain

The most

primitive of the

three main

divisions. Major

structures >

medulla, pons,

andcerebellum.


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The Brain

Q i Ti e an aT n re e e re r

are nee e ee hi i re

Balan e

an

ve en


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The Midbrain

The midbrain,

pons, and

medulla lie on

top of the spinalcord. Together

they make up

the brain stem.


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The Forebrain

The forebrain

consists of

subcorticalstructures and the

two hemispheres

of the cerebral

cortex


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The Corpus Callosum

Millions of myelinated

axons connecting the

brains hemispheres


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Subcortical Structures

Thalamus

Likearelay

stationtoareas

ofthecortex


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Thalamus


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Hypothalamus


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The Cortex

The cerebral cortex covers the forebrain

and is divided into four lobes:

frontal

parietal

temporal

and occipital


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Occipital lobe

Visual center


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Parietal lobe

Includes

somatosensory

cortex (input

fromenvironment)

Helpsprocess

perceptions


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Temporal lobe

Hearing

Understanding

language

Memory


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Frontal lobe

Youare whoyouare

becauseofthis lobe.

Personality

EmotionsControlling

judgment

Impulses

Sexual behavior

Using LanguageMovement

MotorCortex


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Somatosensory and Motor Cortexes


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More About the Brain

Aphasia

uickTime and aTIFF (Uncompressed) decompressor

are needed to see this picture.


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AphasiaCAT Scan


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Apraxia of lid

opening

(blepharospasm)

ApraxiaLoss or impairment

of the ability to

execute complex,coordinated

movements without

impairment of the

muscles or senses.


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Split-Brain and Lateralization


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Split-Brain Experiment


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The Endocrine System

Endocrine system: Ductless glands that

regulate growth,reproduction,

metabolism, mood,and some behavior

Hormones: Chemical messengers

secreted into thebloodstream


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Cortisol:

CortiSlim?

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re needed to see this ict re.


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Cortisol is the body's mainstress hormone, and isrequired for many vitalpurposes -- proper glucosemetabolism, blood pressure,immune function andinflammatory response are afew. In times of stress, eithermental or physical, the bodycan produce an excessiveamount of cortisol. At thesehigh levels, cortisol is a nastylittle number indeed. It cannegatively affect cognitiveperformance, suppress thyroidfunction, foster blood sugar

imbalances and thesubsequent deposition of bodyfat, decrease bone density, aswell as other things. Athletesdon't like cortisol, as it iscatabolic -- i.e., muscle-wasting, rather than anabolic -- i.e., muscle building.

Biological Foundation of Behavior

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