Introduction to Neuroscience

1. Neuroscience
Dr. Irene Karayianni

2. The Neuron

4. Shapes of neurons
Multipolar neuron
one axon and many dendritic branches
Bipolar neuron
one axon and one dendritic branch
Usually sensory
Unipolar neuron
one axon and one dendritic branch
Usually sensory
Pyramidal neuron
shape of their cell body, looks like a pyramid. They
have one axon and two main dendrite branches
Purkinje neuron
one axon and a very dense and complicated
dendrite arrangement
Found in the cerebellum, the part of the brain that
controls balance, coordination, and timing of
actions.
Specialized to be good at different things

5. Neuron structure
1 Cell body (soma)
2 Nucleus – incorporated hereditary material
3 Dendrites
4 Axon
5 Terminal buttons
6 Myelin sheath – protective coat of protein & fat; insulates, serves to increase
velocity
7 Schwann’s cells
1 2
3
4
5
6 7
(transmit messages)
(receive messages)

6. Glial cells support neural functioning
Hold neurons in place; nourishment; insulation; help repair damage

7. Types of neurons
• Sensory neuron: takes a message from a receptor in a sense organ to
the CNS. Long dendrite, short axon
• Motor neuron: takes message from CNS to a muscle or a gland. Short
dendrite, long axon.
• Interneuron: connector neuron, conveys messages between parts of the
CNS. Short dendrites, short/long axon.

8. Neural networks

9. Neurons are…
&
With built-in supplies of electrical power

10. Neuron communication
1
Neural transmission
electrical
2
Synaptic transmission
chemical
https://www.youtube.com/watch?v=-SHBnExxub8

11. How neurons fire
All-or-none law
Resting state
Inside Negative charge -70 millivolts
Action potential
Inside Positive charge

12. Communication within neuron
electrical impulse

13. Communication within neuron
electrical impulse
Polarity
(charge difference)
Before the neuron is triggered
Resting state
++++++++++++++++
++++++++++++++++
- - - - - - - - - - - -
- - - - - - - - - - - -

14. Communication within neuron
electrical impulse
Action potential
++++++++++++++++
++++++++++++++++
+++
+++
- - - - - - - - - -
- - - - - - - - - - -
Gates open
Depolarization  chain of events

15. Communication within neuron
electrical impulse
Action potential
++++++++++++++++
++++++++++++++++
+++
+++
- - - - - - -
- - - - - - - -
- - -
- - -
+++
+++
the movement of ions causes a change in charge from negative
to positive in successive sections of the axon

16. Communication within neuron
electrical impulse
Just after an AP has passed through a section of the axon
++++++++++++++++
++++++++++++++++
+++
+++
- - - - -
- - - - - -
- - - - -
- - - - -
Reload
Gates closed

17. Communication within neuron
electrical impulse
Differences in
SPEED (3-360 km/h) - determined by axon’s size and thickness of myelin sheath
STRENGTH - potential rate of firing (up to 1000 times/sec) – depends on intensity of stimulus

18. Mirror neurons .
understand others’ intentions
capacity of young children to imitate others
empathy— concern, compassion, sympathy
development of language

19. The synapse

20. The synapse

21. The synapse

22. The synapse
• several types of NTs, and not all neurons are capable of receiving
the chemical message carried by a particular NT
• each kind of neurotransmitter has a distinctive configuration that
allows it to fit into a specific type of receptor site on the receiving
neuron

23. Excitatory and inhibitory messages

24. Reuptake
If neurotransmitters remained at the site of the synapse, receiving neurons would be awash in
a continual chemical bath, producing constant stimulation or constant inhibition
Deactivation by enzymes
Or
Chemical recycling

25. Neurotransmitters
>100
Serotonin and Endorphins
Technically,
the only things you enjoy
NTs are a particularly important link between the nervous system and
behavior
Deficiency or excess

26. Neurotransmitters . .
• Acetylcholine: activates skeletal muscles (The paralytic arrow-poison curare
acts by blocking transmission at these synapses). Also involved in memory, and
diminished production may be related to Alzheimer’s
• Glutamate: memory, regulation of emotion
• GABA: the primary inhibitory neurotransmitter. It moderates a variety of
behaviors, ranging from eating to aggression. Several common substances, such
as the tranquilizer Valium and alcohol, permit GABA to operate more efficiently.
• Dopamine: movement, attention, focus, learning. Linked to pleasures related
to motivation and emotional arousal. Dopamine deficiency is linked to
Parkinson’s. Dopamine overproduction is linked to schizophrenia
• Serotonin: regulates sleep, eating, carbohydrate cravings, mood, temperature,
and pain. Linked to alcoholism, depression, suicide, impulsivity, aggression, and
coping with stress
• Endorphin: similar to painkiller morphine. Deals with pain, elevates mood.
• Norepinephrine: focus, alertness
• Epinephrine: fight or flight
https://www.youtube.com/watch?v=haNoq8UbSyc

27. Neural connections
Each neuron can be connected to 80.000 other neurons
MANY neural connections
Messages are also communicated by chemicals in the endocrine system

28. Nervous system

30. Central nervous system
Peripheral nervous system
Thickness of a pencil 
Communication
Reflexes

31. Reflexes - Types of neurons
• Sensory neuron: takes a message from a receptor in a sense organ to
the CNS. Long dendrite, short axon
• Motor neuron: takes message from CNS to a muscle or a gland. Short
dendrite, long axon.
• Interneuron: connector neuron, conveys messages between parts of the
CNS. Short dendrites, short/long axon.
Quadriplegia
Paraplegia

32. Peripheral NS

33. Autonomic NS
The autonomic division plays a crucial role during emergencies
The sympathetic and parasympathetic divisions work together to
regulate many functions of the body

34. The endocrine system
• A chemical communication network that sends messages throughout the
body via the bloodstream.
• Secretes hormones, chemicals that circulate through the blood and
regulate the functioning or growth of the body.
– travel slower than neurotransmitters
– travel throughout the body, similar to the way radio waves are transmitted -
cells must be receptive
• Influences—and is influenced by—the functioning of the nervous system.
• Closely linked to the hypothalamus.

35. Pituitary (hypophysis): key component of ES
growth, blood pressure, certain functions of
the sex organs, thyroid glands and
metabolism, some aspects of pregnancy,
childbirth, nursing, water/salt concentration,
temperature regulation, pain relief.
Master gland, but servant of the brain

36. Endocrine system
and glucagon
cortisol

37. Hormones
Oxytocin:
• in new mothers, oxytocin produces an urge
to nurse newborn offspring.
• Stimulates cuddling
• in rats—it encourages males to seek out
females more passionately, and females to
be more receptive to males’ sexual
advances.
• Related to the development of trust in
others

38. The brain
3D BRAIN  http://www.g2conline.org/
greatest natural marvel
1.5 kg
biocomputer
No straightforward one-to-one correspondence
exists between a distinct part of the brain and a
particular behavior

39. Studying the brain

40. Studying the brain
Electroencephalogram (EEG)
records electrical activity in the brain

41. Studying the brain
Functional magnetic resonance imaging (fMRI)
changes in blood oxygenation and flow
able to view features of less than a millimeter in size and view changes
occurring in intervals of 1∕10 of a second
shows operation of individual bundles of nerves
Improved diagnosis of diseases (chronic back pain – stroke – Alzheimer’s, MS)

42. Studying the brain
Positron emission tomography (PET)
biochemical activity within the brain at a given moment
injection of a radioactive liquid into the bloodstream, which makes its
way to the brain
Memory problems, brain tumors

43. Studying the brain . .
Transcranial magnetic stimulation (TMS)
exposes a region of the brain to a strong magnetic field  momentary
interruption of electrical activity  note the effects of this interruption
on normal brain functioning
Virtual lesion
Treat several disorders (depression, schizophrenia)

44. The old brain – the central core
• We share some basic functions with more
primitive animals
• directed by a relatively primitive part of
the brain

45. The old brain – the central core
reticular formation
the brain’s guard. It arouses the
cerebral cortex to attend to new
stimulation and keeps the brain alert
even during sleep.
1. Hindbrain: Medulla, pons, cerebellum

46. The old brain – the central core
• Regulates unconscious function: breathing,
reflexes, heartbeat, blood pressure,
circulation, digestive system activity,
vomiting
• People who experience brain damage can
still have functioning bodies, as long as the
medulla oblongata is working.
• Damage: fatal / unable to breath, swallow
medulla

47. The old brain – the central core
• Contains large bundles of nerves
• Joins 2 halves of cerebellum
• Sleep regulation
• Transmits motor information
– Coordinates muscles, integrates movement
between right and left part of the body
• Involved in eye movements, facial
expressions, chewing, feeling the face,
biting, swallowing
– Important nerves originate in the pons
pons

48. The old brain – the central core
• Latin for ―little brain‖
• Contains half the brain's neurons
• Coordinates bodily movements, posture, and
body balance
– important for learning motor behaviors
– Damage to the cerebellum interrupts the flow
of smooth movement, causing it to appear
uncoordinated
• Involved in several intellectual functions,
ranging from analysis and coordination of
sensory information to problem solving
cerebellum

49. The old brain – the central core
2. Reticular formation
reticular formation
Sleep, arousal, attention; the brain’s guard. It arouses
the cerebral cortex to attend to new stimulation. filters
out background stimuli to allow us to sleep undisturbed
necessary for maintenance of consciousness - coma

50. The old brain – the central core
3. Thalamus, hypothalamus
reticular formation
the brain’s guard. It arouses the
cerebral cortex to attend to new
stimulation. filters out background
stimuli to allow us to sleep undisturbed

51. The old brain – the central core
• relay station for information about the
senses
– channels incoming stimuli from the sense
organs to the appropriate parts of the brain so
that it can be processed
– Messages from the eyes, ears, and skin
• integrates information from higher parts of
the brain, sorting it out so that it can be sent
to the cerebellum and medulla
thalamus

52. The old brain – the central core
• Link to the endocrine system
– Links the nervous system to the endocrine
system
– Governs release of other hormones in the body
– Homeostasis – internal balance - constant body
temperature and monitors the amount of
nutrients stored in the cells
• Important role in emotion, motivation and
stress
• Regulates hunger, thirst, self-protection, sex,
sleep and circadian rhythms
– Hypothalamic diseases can include appetite and
sleep disorders
hypothalamus

53. The old brain – the central core
thalamus hypothalamus
medulla pons cerebellum
Reticular formation

54. The limbic system
self-preservation, eating, aggression, reproduction, learning, memory and
experience of pleasure, expression of emotions
reticular formation
the brain’s guard. It arouses the
cerebral cortex to attend to new
stimulation and keeps the brain alert
even during sleep. https://www.youtube.com/watch?v=u76jBk59RFk

55. The limbic system
self-preservation, eating, aggression, reproduction, learning, memory and
experience of pleasure, expression of emotions

56. The limbic system
self-preservation, eating, aggression, reproduction, learning, memory and
experience of pleasure, expression of emotions
• Patients with epilepsy. In an attempt to stop their seizures 
portions of the limbic system removed  difficulty learning and
remembering new information.
• E.g. unable to remember where he lived, although he had resided at
the same address for eight years.
• E.g. even though the patient was able to carry on animated
conversations, he was unable, a few minutes later, to recall what
had been discussed.

57. • Forming new memories
• Brings cognitive elements to the processing
of emotional information
• Ties together sights, sounds and meaning
• Involved in spatial memory
• Alzheimers’ partially results from
hippocampus damageHippocampus
The limbic system
self-preservation, eating, aggression, reproduction, learning, memory and
experience of pleasure, expression of emotions

58. • Emotions, fear, aggression
• Emotional learning - Formation of memories
about emotionally charged events
– Injury  from docile to beast and vice versa
• Feeding, drinking, sexual behavior
Amygdala
The limbic system
self-preservation, eating, aggression, reproduction, learning, memory and
experience of pleasure, expression of emotions

59. Cerebral cortex – the new brain
sulci
Thinking,
remembering,
deciding
Speaking
Sense of touch & senses

60. Cerebral cortex – the new brain
Motor, sensory, association areas

61. Cerebral cortex – motor area

62. Cerebral cortex – sensory area
3 regions
• Body sensations (touch and pressure)
• Sight
• Sound
perceive touch & pressure in particular
area of the body

63. Cerebral cortex – association areas
higher mental processes such as thinking, language, memory, and speech
make up a large portion of the cerebral cortex
consist of the sections that are not directly involved in sensory processing or movement
control executive functions : planning, goal setting, judgment, and impulse control