1. Exploring the Human Brain
(Part 2)
Mohammed El Majdoubi, Ph.D.
Associate Professor of Neurobiology

2. The Three Units of the Human Brain

3. Brains

4. Brain size and intelligence

5. The study of brain function dates back to 1770’s.
Franz Josef Gall: Phrenology

6. Studying the Brain
Scientists study the functions of parts of the brain by observing the behaviour of people who have suffered brain damage or have degenerative brain diseases.
Scientists also use animal studies to investigate brain functioning.
Phineas Gage: experienced personality and behavioural changes after damage to his frontal lobe

7. Brain Imaging Techniques
Enable investigators to look inside the living brain, understand relationships between specific areas and their functions, and locate brain areas that are affected by neurological disorders
Computed Tomography Scan (CT Scan): Uses a series of X-rays passed through the head. This technique shows structure of brain on film but not function
Positron Emission Tomography (PET Scan): A scanner detects radioactive material (oxygen, fluorine, carbon and nitrogen) that is injected or inhaled to produce brain images. This method detect area that are metabolically active and provide a functional view of the brain.

8. Brain Imaging Techniques
Functional Magnetic Resonance Imaging (fMRI): Uses the detection of radio frequency signals produced by displaced radio waves in a magnetic field. fMRI detects changes in brain flow to particular areas of the brain and provides anatomical and functional views of the brain
Diffusion Tensor MRI: monitors the movement of water in the brain and provides novel, histological and anatomical information about tissue structure, composition, architecture, and organization.

9. The Human Brain
Corpus callosum

10. Brain Has Areas Specialized For Certain Functions

11. In the 1950’s, Penfield did some work to show the…
Homunculus
“little man”
…specificity of function of the cortex.

12. Cerebral Hemispheres
Male vs. Female Brains…

13. Split Brains

14. Language Areas
Located in a large area surrounding the left (or language dominant) cerebral hemisphere:
Broca’s area - speech preparation and production
Wernicke’s area - language comprehension and word analysis

15. Limbic System * * *

16. What Are Emotions?
Emotions can be seen as a bridge between input (sensory) and output (behavior)
Emotions - evaluative, personal, reaction to things and events
Emotions help determine what is reacted to and how
Positive Emotions – involves the nucleus accumbens: Excitement
Negative Emotions – involves amygdala & insula: Fear
Emotions provide a fast intuitive evaluation (gut feeling) of the perceived situation before sending it to the reasoning brain to create the narrative of what just happened

17. Facial Expression is an INNATE behavior
Neil Carlson, Physiology of Behavior, 2001.

18. Categories of Memory 1- Fact (declarative) memory: 2- Skill memory:
Entails learning explicit information
Is related to our conscious thoughts and our language ability
Is stored with the context in which it was learned
2- Skill memory:
Less conscious than fact memory and involves motor activity
It is acquired through practice
Skill memories do not retain the context in which they were learned

19. Memory Memory is the storage and retrieval of information
1- Short-term memory (or working memory):
Last seconds to hours
Limited to 7 or 8 pieces of information
2- Long-term memory: Has limitless capacity…

20. Your hypothalamus “senses” a need...
♥SLIDE #16: HYPOTHALAMUS
 Your hypothalamus, a very tiny area at the base of your brain, gets information for a lot of different behaviors that help to keep you alive.
 It gets information about your energy supplies, water, temperature, sleep and even social needs.
 It then sends out signals to other parts of your brain so that you do things to alleviate or get rid of your needs….you get food if you are hungry, water if you are thirsty, sleep if you are tired, put on a coat if you are cold or find a friend if you need a hug.
….makes you “behave” to alleviate the need.

21. Automatic Behaviors ♥SLIDE #13: AUTONOMIC NERVOUS SYSTEM
 Automatic behaviors are controlled by your autonomic nervous system (ANS).
 This system is made up of parts of your brain, spinal cord, and nerves coming out from your brain and spinal cord.
 It is divided into the parasympathetic system or rest and digest system.
 This system slows your body down – decrease heart rate, respiration, start gastrointestinal system so you can store energy.
 The other part of the ANS is the sympathetic system or fight or flight system.
 This system speeds up your body – increase heart rate, respiration, stop gastrointestinal system so you can get blood to your muscles so you can move.

22. Brainstem Consists of three regions: midbrain, pons, and medulla
Controls automatic behaviors necessary for survival

23. Reticular Formation
Complex network of nerve fibers with far-reaching axonal connections that send impulses to the cerebral cortex to keep it conscious and alert.
Decreased activity in the reticular formation results in sleep
If the reticular formation ceases to function (injury), the person remains unconscious even with strong stimulation (= comatose state).

24. Electroencephalogram (EEG) Test

25. Sleep Slow wave sleep (NREM): Rapid eye movement sleep (REM):
Occurs when a person is very tired
Reflects decreasing activity of the reticular formation
Restful, dreamless, and accompanied by reduced blood pressure and respiratory rate.
May range from light to heavy and last from minutes.
Rapid eye movement sleep (REM):
Also called “paradoxical sleep” because some brain areas are active
Heart and respiratory rates are irregular
Vital signs increase
The eyes can be seen rapidly moving beneath the eyelids
Skeletal muscles (except ocular muscles) are paralyzed
Most dreaming takes place during REM sleep
Lasts from 5-10 minutes and alternate with slow wave sleep

26. Stages of NREM sleep
Stage 1 – eyes are closed and relaxation begins; the EEG shows alpha waves; one can be easily aroused
Stage 2 – EEG pattern is irregular with sleep spindles (high-voltage wave bursts); arousal is more difficult
Stage 3 – sleep deepens; theta and delta waves appear; vital signs decline; dreaming is common
Stage 4 – EEG pattern is dominated by delta waves; skeletal muscles are relaxed; arousal is difficult

27. The cerebellum also known as the “little brain” is involved in motor control.

28. Aging
1. Normal Aging (or senescence) causes changes in mental ability, emotional and behavioral reactions, muscle activity, and motor coordination.
2. Age-associated changes may be due to:
Cell death
Neuronal atrophy
Loss of white matter
3. Aging is accelerated by age-related disorders:
a. Parkinson’s disease
b. Alzheimer disease

29. Alzheimer’s Disease

30. Neuroplasticity
Fact: Brain continues to adjust and reorganize itself by forming new neural connections throughout life.
Neuroplasticity: The ability of neurons to change their function, chemical profile or structure. This allows them to compensate for injury and adjust their activity in response to new situations.
Neuroplasticity includes:
Cellular recovery after injury (activity is crucial for recovery)
Habituation (decrease in response to a repeated benign stimulus)
Learning and memory
Neurogenesis increases with environmental stimuli. Use it or lose it…

31. Neurogenesis

32. Thank you!