Stimuli can elicit reflexive or voluntary responses in organisms. A reflex is an involuntary, rapid response that involves at least three neurons: a sensory neuron that detects the stimulus, a relay neuron that passes the message to a motor neuron, which initiates the response in an effector like a muscle. Reflex arcs allow for quick, protective responses without conscious thought. Voluntary responses involve higher-level processing and are under conscious control.

1. NEUROLOGY AND BEHAVIOR

2.  Stimulus – a change in the external or internal
environment that is detected by a receptor and
brings about a response.
 Response – change in an organism due to a
stimulus.
 Reflex – a rapid and “unconscious” response
 Require a precise pathway – at least 3 synapses
 Include 6 parts: >>>>>>>>>>>>>>>>>>>
REFLEXES and REFLEX ARCS

3.  Receptor – detects stimulus, transforms into an impulse
 Sensory Neurons –
 part of the PNS
 connects receptor to CNS thru dorsal nerve root
 Impulse travels freely along the axon
 Relay Neuron –
 receives messages from sensory neurons across
synapses - passes them to motor neurons
 Within gray matter of spinal cord

4.  Motor Neurons –
 Part of the PNS
 Carries impulse from CNS (relay neuron) to
effector (muscle)
 Leaves thru ventral root of SC
 Cell body is in gray matter SC
 Gray Matter – region of synaptic connection in
the SC
 Effector – carries out response

8.  The mechanism of evolution- requires:
 Variations in phenotypes
 Genetic basis for variation
 Change in the environment
 Examples: 2 related to global warming:
 Sylvia atricapilla – Black Cap - migration
 Parus major – Great tit - breeding

10.  MIGRATION PATTERNS
 Normal breeding – early summer across central and
northern Europe.
 Then migrates to warmer areas before winter.
 Patterns show normal migratory pattern – Germany to Spain
 Recent studies – 10% migrating to the UK
 Experiments show that direction of migration is
genetically inherited.

12.  Breed in spring/early summer through Europe.
 Timing of egg laying is genetically programmed
 Day length determines time of year.
 Recent studies have shown that egg laying time is
becoming earlier.
 Have greater reproductive success
 due to earlier opening of leaves on trees & biomass that feeds
on the leaves –
 Biomass – food for the great tit!

13. Types of Receptors
Mechanoreceptor – pressure, texture, vibrations (ear)
Chemoreceptors – chemical solutes and vapors
Photoreceptors – react to light
Thermoreceptors – change in temperature

15.  Choroid – light absorbing pigment; stray light
 Retina – receptors for vision; rod cells
 Fovea – densely packed cone cells; acute vision
 Optic nerve – carries nerve impulses to brain
 Optic disk – blind spot
 Vitreous humor – supports eye; transparent
 Lens – focuses light
 Aqueous humor - supports eye; transparent
 Pupil – light enters here
 Iris – regulate size of pupil
 Cornea – outer layer; fixed focusing
 Sclera and conjunctiva – white; protects and supports
 Rod cells – black and white sensors; dark light
 Cone – color sensors; bright light

16. The Perception of Light

18. Rod cells Cone cells
Light brightness
Diversity of cells
Wavelength sensitivity
Impulse: neuron ratio
distribution

21. Edge Enhancement – pre
central nervous system;
carried out on the retina
itself.

23.  Gray areas – peripheral vision; fewer light sensitive
cells
 Focused attention on any gray area – use center of
the retina.

25. Contralateral Processing – is
the way the brain collects and
integrates information to
create the perception of
seeing.

27. Both eyes send information and sends to both sides
of the brain.
n Optic chiasm – where information crosses to the
other side of the brain
e Both eyes are responsible for processing information
from both eyes.

28.  HOW DOES VISION WORK
 BLIND SPOTS
 OPTICAL ILLUSIONS

30. 1. Eardrum – pressure waves causes the eardrum to vibrate
2. Hammer, Anvil, Stirrup – eardrum pushes on bones of the
middle ear; magnifies 20x.
3. Oval Window – middle ear bones push on membrane ; causes
cochlea to move
4. Cochlea – pressure wave travels through fluid
r Sensory cilia in cochlea move
Causes the release of neurotransmitters between receptor and auditory
nerve.
s Auditory nerve – generates an impulse.
Impulse is carried to the brain for translation
________________________________________________
 Semicircular canals – responsible for balance
 Eustachian Tube – functions to equalize air pressure and drains
mucus
Hearing Test

31. Learned Behavior Innate Behavior
 Experience  Instinctive
 Modified by trial and  Genetically based
error  Not modified
 Variation within  Uniform throughout
population population
 Affected by environment  Unaffected by
 Capacity to learn may environment
product of natural  Beneficial behaviors
selection rather than product of natural
specific behaviors selection
Learned or Innate??

32. INNATE LEARNED
 Sucking instinct
 Emotional expressions
 Training animals
 Birds hatching
 Walking
 Migratory patterns
 Learning to drive
 Hunting instinct
 Tying shoes
 Not breathing
underwater
 Courtship and sexual
behavior in species
 Reflexes – all
 Instincts

33.  A directional response to a stimulus:
 Positive or Negative
 Chemotaxis – response to chemicals
 Phototaxis – response to light
 Gravitaxis – response to gravity
 Rheotaxis – response to water current
 Thigmotaxis – response to touch
Paramecium

34.  Response to a non directional stimulus:
 Humidity – a non directional stimulus
 Orthokinesis – speed of movement altered
 Klinokinesis – rate of turning

35. Allows an organism to
change or adapt in
response to the
environment which gives
an increased chance of
survival

36. Non-associative Associative
 Habituation – repeated stimulus  Imprinting – learned early in
brings about decreased life – very receptive
response. No reward or  Forms instant bond with one
punishment who provides the essential skills
 Sensitization – increased for survival
response to a stimulus after a  Conditioning – reward or
punishing stimulus punishment
 Classical – Pavlovian
Crow Response  Operant – behave to win award
or avoid punishment
 Training
 A good example

37. Pavlovian Conditioning
You Tube Pavlov

38. 1. Unconditioned Response – automatic to the
stimulus (food elicits salivation)
2. Neutral Stimulus – no response (bell ringing)
3. Conditioning – neutral and unconditioned
combined (dog associates bell with food and
salivates)
4. Conditioned Stimulus and Response (dog will
salivate when bell rings – even without food)
Example Example

39.  Watch the video: To what extent do cowbirds learn
their sons socially and how much is innate?
Birdsong and Culture
 Birdsong
 Strong indicator of reproductive fitness
 Females select males based on RF
 Exaggerates traits - Lyre

41.  How do neurons talk to each other?
Through the SYNAPSE.
Most are chemical.
 2 main types:
 Excitatory – normal synapse.
 Neurotransmitter released by presynaptic neuron (axon)
 Causes positive ions to enter the post synaptic neuron
(dendrite)
 Acetylcholine and dopamine
 Inhibitory
 Opposite effect – carry negative ions – Chloride - - into the
post synaptic neuron. Increases polarization –
hyperpolarization.
 Makes it difficult to produce an action potential
 Dopamine and GABA

43.  Important Points:
 Axons of many neurons feed into the dendrite of the post synaptic
neuron.
 Each axon contributes to a membrane potential.
 The effects of each can be excitatory or inhibitory.
 The effect is summative---- and if it reaches Threshold, an AP is
propagated.
 Effects of excitatory neurotransmitters can be cancelled by inhibitory
neurons.
 AP at postsynaptic neuron is determined by summation of
messages.
HOW IT WORKS!

44. Psychoactive Drugs
Affect the brain and
personality by either
increasing or decreasing
post-synaptic transmission.

45. Cholinergic vs. Adrenergic
 Cholinergic –
 Synapses using acetylcholine as the neuroT
 Acetylcholine – parasympathetic of PNS
 Importance in keeping “normalcy”
 Response = relaxing
 inhibitory
 Adrenergic –
 Synapses using noradrenalin as the neuroT
 Noradrenalin – sympathetic of PNS
 Importance for “alertness,” increased energy, & euphoria
 stimulant

46. Excitatory Drugs
 Nicotine –
 similar to acetylcholine --- fits in receptor
 Mimic excitatory neurotransmitters/ block inhibitor
 Is not broken down by enzymes - remains

47. Excitatory Drugs
Amphetamines –
 stimulate release of noradrenalin and
dopamine
 Moves directly into pre-synaptic neuron
vesicle.
 Results increased awareness and energy

48. Excitatory Drugs
COCAINE –
Normal
 Dopamine and adrenaline act as excitatory neurotransmitters
 Both usually taken back up at the pre synaptic axon or enzyme.
With Cocaine
 Blocks receptors on the re-uptake pump
 NT/hormone remains and more is released
 Increases post-synaptic transmission
 Changes –
 Dopamine is a pleasure NT
 Euphoria, increased energy, alertness
 Highly addictive – body produces less natural dopamine

49. Inhibitory Drugs
 BENZODIAZAPINES
 (gamma-Aminobutyric acid) main
inhibitory NT
 Enhance the effect of GABA (main
inhibitory NT)
 Combines with and slows down GABA
receptors on post-synaptic neurons
 Slows down brain activity.

50. Inhibitory Drugs
Alcohol
 Initially acts as a stimulant
 Release of dopamine
 As level of BAC raises – has a
sedative effect
 Increases binding of GABA
 Acts as an anesthetic

51. Inhibitory Drugs
Tetrahydrocannabinol
 Cannabis –
Normal
 Dopamine and GABA proceed when needed
With THC
 THC inhibits GABA release
 GABA cannot inhibit dopamine
 Mood and Behavior
 Increased feelings of pleasure
 Intoxicated, hunger, memory loss,
 Used to treat nausea in cancer patients.

52. ADDICTION (Mouse Party)
 A chronic neurological disorder
with:
Genetic characteristics
Psychosocial characteristics
Environmental characteristics
Changes in the brain result in
compulsive desire to use a drug

53. General Causes of Addiction
 Genetic – not fully understood
 Different allele for a receptor?
 Carry modified versions of genes linked to drug
metabolism
 Susceptibility does not mean inevitability.
 Psychosocial/ Environmental
 Peer pressure
 Timing
 Availability
 Legality/Religion
 Community
 Family
 Mental health

54. END

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