The Biology of Mind and Consciousness Chapter 2 part II

1. The Biology of Mind and ConsciousnessChapter 2part 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 evolutionarilyoldest 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

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 plasticityallows 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