The Central Nervous System

1. The Central Nervous System Spinal cord - Interface between the peripheral and central nervous systems - Carries reflexes, sensory, and motor information - 31 pairs specialized nerves (brain has 12 pairs – the cranial nerves)

2. The Brain • Squishy • Weighs about 3 pounds • Most complex structure in known universe. • So how do you study this thing?

3. Studying the brain • Surgical – can implant electrodes • Electrical and imaging Electrical – • Electroencephalography (EEG) • Electromyography (EMG)

4. Electroencephalogram (EEG) • recording of the waves of electrical activity that sweep across the brain’s surface • measured by electrodes placed on the scalp

5. Neuroimaging • CT (computed tomograph) Scan • a series of x-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body. Also called CAT scan for Computerized Axial Tomography. • PET (positron emission tomograph) Scan • a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.

6. PET Scan

7. Neuroimaging • MRI (magnetic resonance imaging) • a technique that uses magnetic fields and radio waves to produce computer – generated images that distinguish among different types of soft tissue; allows us to see structures within the brain. • Also known as fMRI (functional magnetic resonance imaging) • Can do real-time scans to see the brain at work.

8. MRI Scan

9. Da’ brain • Major parts : • Hindbrain • Midbrain • Subcortical forebrain • Cerebral cortex

10. The Hindbrain • Brainstem • the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull • responsible for automatic survival functions • Medulla [muh-DUL-uh] (aka Medulla Oblongata) • base of the brainstem • controls heartbeat and breathing

11. The Hindbrain • Pons • “switchboard” connecting cerebral cortex to cerebellum • Reticular Formation(extends into midbrain) • a nerve network that plays an important role in controlling alertness

12. The Hindbrain (pons & medulla plus some other junk…)

13. The Hindbrain • Cerebellum [sehr-uh-BELL-um] • the “little brain” attached to the rear of the brainstem • it helps coordinate voluntary movement and balance

14. The Midbrain • Involved in vision and hearing • Parts of reticular formation, eye & body movement • Includes the substantia nigra that produces dopamine.

15. The Subcortical Forebrain • Thalamus [THAL-uh-muss] • the brain’s sensory switchboard, located on top of the brainstem • directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla • Basal ganglia • Near the thalamus • Movement, posture, also certain types of judgments

16. The Subcortical Forebrain • Electrode implanted in reward center in hypothalamus

17. The Cerebral Cortex • Cerebral Cortex • the intricate fabric of interconnected neural cells that covers the cerebral hemispheres • the body’s ultimate control and information processing center • Glial Cells • cells in the nervous system that are not neurons but that support, nourish, and protect neurons

18. The Cerebral Cortex • Frontal Lobes • involved in speaking and muscle movements and in making plans and judgments • Parietal Lobes • include the sensory cortex • Occipital Lobes • include the visual areas, which receive visual information from the opposite visual field • Temporal Lobes • include the auditory areas

19. The Cerebral Cortex

20. The Cerebral Cortex • Motor Cortex • area at the rear of the frontal lobes that controls voluntary movements (aka primary motor area) • Sensory Cortex • area at the front of the parietal lobes that registers and processes body sensations (aka primary somatosensory area)

21. The Cerebral Cortex

22. The Cerebral Cortex • Functional MRI scan of the visual cortex activated by light shown in the subject’s eyes`

23. Visual cortex Auditory cortex Visual and Auditory Cortex

24. Association Areas • areas of the cerebral cortex that are not involved in primary motor or sensory functions • involved in higher mental functions such as learning, remembering, thinking, and speaking

25. The Cerebral Cortex • Aphasia • impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding) • Broca’s Area • an area of the left frontal lobe that directs the muscle movements involved in speech • Wernicke’s Area • an area of the left temporal lobe involved in language comprehension

26. Specialization and Integration

27. Specialization and Integration • Brain activity when hearing, seeing, and speaking words

28. Brain Reorganization • Plasticity • the brain’s capacity for modification as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development

29. Our Divided Brain • Hemispheric specialization (or “cerebral lateralization”) • Found in lots of species (even beta fish!) • True, and important, but don’t overdo it…

30. What most people believe...

32. Corpus callosum Our Divided Brain • Corpus Callosum • largest bundle of neural fibers • connects the two brain hemispheres • carries messages between the hemispheres

33. Our Divided Brain • The information highway from the eyes to the brain

34. Split Brain • a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them

35. Split Brain “What word did you see?” or “Point with your left hand to the word you saw.” Two words separated by a dot are momentarily projected. “Look at the dot.”

36. Percentage of left-handedness 14% 12 10 8 6 4 2 0 The percentage of lefties sharply declines with age 10 20 30 40 50 60 70 80 90 Age in years Disappearing Southpaws • The percentage of left-handers decreases sharply in samples of older people (adapted from Coren, 1993).

37. Corpus callosum Cerebral cortex Right hemisphere Thalamus Left hemisphere Hypothalamus Pituitary Amygdala Reticular formation Medulla Hippocampus Spinal cord Cerebellum Cerebral cortex Limbic system Brainstem