1. The Biology of Mind and Consciousness Chapter 2 part II

2. The Biology of Mind and Consciousness
The Brain
Older Brain Structures
The Cerebral Cortex
Our Divided Brain

3. Older Brain Structures
Some components of the brain are found in simpler organisms, or at least lower mammals, and function similarly in humans
Brainstem
Thalamus
Reticular Formation
Cerebellum
Limbic System

4. The Brainstem The brain’s oldest and innermost region
Begins where the spinal cord enters the skull
Medulla: the base of the brainstem; controls heartrate and breathing
Pons: helps coordinate movements

5. The Brainstem

6. The Reticular Formation
Network of nerves running through the brainstem and thalamus
Reticular = “netlike”
Plays important role in controlling arousal/alertness: if the RF is active, you’re awake; if it’s cut, you’re in a coma
Acts as a filter for some of the sensory messages from the spinal cord to thalamus

7. The Thalamus Area at the top of the brainstem
Joined pair of egg-shaped structures
The brain’s sensory switchboard
Directs sensory messages to the cortex
Transmits replies from the cortex to the cerebellum and medulla

8. Crossover
Nerves to and from each side of the brain connect to the opposite side of the body

9. Review of Brain Structures

10. The Cerebellum

11. The Cerebellum Means “little brain” Integrates sensory input
Coordinates voluntary but unconcious movement (walking, speaking)
Helps judge time, discriminate sounds and textures, and control emotions
Helps process and store unconscious memories (see lightning, except thunder)

12. The Limbic System
Lies in between (the word “limbus” means “border”) the evolutionarily oldest and newest brain areas, and between the cerebral hemispheres (see next slide)
Associated with basic/primitive emotions and drives and memory formation
Includes:
Amygdala
Hypothalamus
Hippocampus

13. The Limbic System

14. The Hippocampus Processes conscious episodic memories
Animals or humans who lose or damage their hippocampus may lose the ability to form new memories of facts and events
Clive Wearing

15. The Amygdala Two lima-bean-sized clusters, one in each hemisphere
Linked to aggression and fear
Removal of rhesus monkeys’ amygdala turned normally aggressive animals very mellow and tame
Note: Aggression and fear involve activity in all levels of the brain, not just the amygdala
Amygdala means almond– lima bean isn’t the only desciption

16. The Cerebral Cortex
Thin layer (“cortex” means “bark”) of interconnected neurons covering the cerebral hemispheres
The body’s ultimate control and information-processing center
Contains networks of neurons responsible for perception, thinking, speaking, and more

17. Structure of the Cortex
Each hemisphere is divided into four lobes

18. Frontal lobe in Teens Frontal Lobe:
Responsible for judgment, decision-making, impulsivity
Teenage brain

19. The Cortex: Motor Functions
The motor cortex, at the rear of the frontal lobes, controls voluntary movements
Body areas requiring precise control occupy the most cortical space (see next slide)

20. The Cortex: Sensory Functions
The sensory cortex, at the front of the parietal lobes, registers and processes body touch and movement sensations
The more sensitive body regions have larger devoted sensory cortex areas

21. Motor and Sensory Cortices

22. The Cortex: Location for Other Sensory Functions
Visual processing occurs in the visual cortex, in the occipital lobes
Sounds are processed in the auditory cortex, in the temporal lobes
Also active during schizophrenic auditory hallucinations

23. Association Areas: Frontal Lobe
Enable judgment, planning, and processing of new memories
Damage may hinder ability to plan for new activities
Damage can have more serious effects: can alter personality and remove inhibitions
Unrestrained moral judgments

24. Phineas Gage 1848: 25-year-old railroad worker
An accident sends a railroad spike through his skull, damaging frontal lobe
Was able to speak and work, but changed from friendly and soft-spoken to being irritable, profane, and dishonest (see next slide)

25. Phineas Gage

26. The Brain’s Plasticity
The bad news
Severed neurons usually do not repair themselves
Some brain functions seem forever linked to specific areas
The good news
The brain’s plasticity allows it to modify itself after some types of damage, especially during childhood
The brain is constantly changing, building new pathways as it adjusts to new experiences

27. How Plasticity Works
The brain often self-repairs by reorganizing existing tissue
It sometimes attempts to mend itself by neurogenesis (producing new neurons)
Baby neurons originate deep in the brain and then migrate elsewhere

28. Our Divided Brain
Our left and right hemispheres exhibit important differences
Language processing resides mostly in the left hemisphere
Damage to left hemisphere seems to have more dramatic effects than to right hemisphere
Until 1960, researchers thought the right hemisphere was “minor” or “subordinate”

29. Right-Left Differences in Intact Brains
Left hemisphere
Quick, literal language processing
Right hemisphere
High-level language processing
Perceptual tasks
Copying drawings, recognizing faces, perceiving differences and emotions, expressing emotion