Behavioral Neuroscience:

Lecture 4

2/02/04

Discussion: Genes and BehaviorAre abilities based in biology or the environment?

Can genes predict success (divorce, intelligence, health, career)?

What if genotypic information was as readily available as your phenotype? Should health care providers or employers

have access to our genotypic information?

Phineas Gage

September 13th, 1848Phineas = 25Rutland & Burlington Railroad, Cavendish, VTPaving the way for new RR tracks“Tamping Iron”

1.25 x 3ft

Phineas Gage: . the historical beginnings of the study of the biological basis of behaviorAccident

Quick RecoveryMonths later: “No longer Gage”

Capable, efficient, best foreman, well-balanced mind Extravagant, anti-social, liar, grossly profane

Stint with P.T BarnumCarriage driver in ChileDied 12 years later

“Intellect unimpaired”

Frontal lobe involved in thinking, planning, setting goals, inhibiting impulses

The brain is not a single or simple entity It’s an integrated system with different specialized

parts Links can be revealed by damage to specific

structures Every sight, sound, taste, twitch, dream, memory,

thought, etc. is biological

How does communication occur?

Electrochemical communication between brain, sensory organs, muscles, and glands

Nervous systemThe Neuron

Structure Action Communication

Brain

THE HUMAN BRAIN: Centerpiece of Nervous System

BRAIN AT BIRTH ==> 25% of adult weight

CONTAINS MOST OF THENEURONS

YOU WILL EVER HAVEABOUT

100 BILLION NEURONS100,000,000,000

Communication NetworksBroad overview: 3 functions

Solve survival problems Receive & transmit signals (brain-body)

Automatically regulates internal states

Transmit from sensory to CNS

Fight or Flight Restore

Sympathetic and parasympathetic divisions of nervous system

Specific Parts: The Neuron Structure

Neurons = building blocks of nervous system

Specific Parts: The Neuron Function

Neurons = 3 functions: Reception, Conduction, Transmission

1.3.

2.

Sensory Neurons (afferent) Neurons that send signals from the senses,

skin, muscles, and internal organs to the CNS

Motor Neurons (Efferent) Neurons that transmit commands from the

CNS to the muscles, glands, and organs

Types of Neurons:

The Withdrawal Reflex

NOTE: Not just one neuron at a time

Complex networks of thousands of neurons sending and receiving are basis of all psychological activity Neural networks = habits

Action I

Messages occur in form of electric impulses http://homepage.psy.utexas.edu/homepage/class/Psy301/Pennebaker/DailyOutlines/Sept08%20Stress/neuricon.gif

Neuron =

Every neuron has membrane Some ions permeate more easily

• Na+ do NOT pass easily• K+ DO pass easily

Resting state = Negative• Negatively charged ions permanently trapped inside cell

W. W. Norton

Action Potential

When dendrites stimulated (IF enough stimulation**)

Delicate balance altered Membrane breaks down Positively charged ions rush in (depolarization)

• Charge = less negative• Action Potential

– Quick burst of electrical energy surges down axon

Relay Race

Action Potential starts at dendrite Through cell body Down Axon Axon Terminals

• How does it get to the next cell’s dendrites?

• Neurons don’t touch–Synapse = millionth inch gap–In synapse = vesicles w/ Neurotransmitters

»Chemical messengers that transmit info

Communication Impulse releases

neurotransmitter from vesicles.

Neurotransmitter enters synaptic gap.

Neurotransmitter binds to receptors on the receiving neuron.

Neurotransmitters

Can be inhibitory or excitatoryWon’t stop until:

Reuptake Enzyme deactivation Autoreception

Neurotransmitters (>75)Acetylcholine (ACh)

1st substance identified as NT Links motor neurons and muscles (contract or relax)

• e.g. curare vs black widow spider Also involved in memory, learning, sleep, dreaming

Endorphins (the brain’s own morphine) 1973 injected rats with morphine Bound like NTs Brain had receptors for exogenous substance?

• Brain must produce its own morphine• Released during pain and discomfort

One Brain or Two?

Right and left sides have different strengths? Right- visual, spatial tasks Left- Reading, verbal processes

Each hemisphere controls opposite side?What if the two sides were disconnected?

“split-brain patients”

Case Study: WJ

1961, W.J. comes to the labCards & blocks

2 red sides 2 white 2 mixed

Use 1 hand to assemble blocks Left hand success vs. right hand success??

Acting as 2 separate brains…

Left hand- YES!Right hand- NO!

Sometimes Left would sneak up to help right! “Each half brain worked outside the conscious

realm of the other”

LATERALIZATION

WHICH FUNCTIONS? Left:

• Adult speech• Literal interpretation• Analytical thinking

Right:• Visual & Auditory patterns• Interpretation of subtleties• Holistic thinking• Face Recognition

The lobes of the cerebral hemispheres

The lobes of the cerebral hemispheres

Planning, decision making speech

Sensory

AuditoryVision