I. The Tools of Discovery: Having Our Head Examined
-How do we “map” the brain?
-The ability to lesion brain tissue
-Cause and effect of damaging different parts of rat brains (starvation vs overeating)
A. Recording the Brain’s Electrical Activity
-Electroencephalogram (EEG)-an amplified readout of the electrical “waves” traveling across the brain’s surface
B. Neuroimaging Techniques
-Computed Tomography Scan (CT 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 a CAT Scan
-Positron Emission Tomography Scan (PET Scan)-A visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task
-Magnetic Resonance Imaging (MRI)-A technique that uses magnetic fields and radio waves to produce computer generated images of soft tissue. MRI scans show brain anatomy.
-Functional MRI (fMRI)-A technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function.
II. Older Brain Structures
-New brain systems built on top of older ones
-Brain size compared to body weight gives SOME indication of intelligence…
-1/45 of weight in humans
-1/600 of weight in elephants
-1/40 of weight in mice
A. The Brainstem
-Medulla-Controls heartbeat and breathing
-Pons-Helps coordinate movements
-Reticular Formation-Filters incoming stimuli and relays it on
-Electric stimulation of the RF (aroused state)
-Severed RF (coma)
B. The Thalamus
-The brain’s sensory switchboard
-Receives info from all senses (except smell)
-Routes info to higher brain
-Also routes some responses to medulla and cerebellum
C. The Cerebellum
-Baseball sized
-“little brain”
-Helps us judge time, modulate emotions, and discriminate sounds and textures
-Coordinates voluntary movement with the pons
D. The Limbic System
-On the border between the “old” brain and the cerebral hemispheres
i. The Amygdala
-Influences aggression and fear
-Lesion on the amygdala of a rhesus monkey
-Electrical stimulation elicited fear and rage
ii. The Hypothalamus
-Directs several maintenance activities
-Eating, drinking, body temperature
-Helps govern the endocrine system
-Linked with emotion and reward
-Rats with electrodes
III. The Cerebral Cortex
-Old brain sustains basic life functions and emotions
-Higher level thinking takes place in the cerebrum
-Makes up 85% of the brain’s weight
-Ability for learning and thinking, not instincts or genetic encoding
A. Structure of the Cortex
-Glial “glue” Cells-Nourish neurons
-Frontal-speaking, muscle movement, making plans and judgments
-Parietal-receives sensory input for touch and body position
-Occipital-receives information from the visual fields
-Temporal lobes-Auditory areas. Receives information from opposite ear
B. Functions of the Cortex
-Mapping is necessary
-Cutting the cord on a TV causes the picture to go blank, but we haven’t destroyed the signal
-What is controlling what?
i. Motor Functions
-1870-Discovery of the motor cortex
-Electric stimulation of the motor cortex would cause movement to happen on the opposite side of the body
a. Mapping the Motor Cortex
-No sensory receptors in the brain
-Experimenting on patients who are wide awake
-More space=more control
b. Neural Prosthetics
ii. Sensory Functions
-Motor cortex is sending messages out to the body
-Sensory cortex is receiving information and processing it
-Different areas receive different input
-Occipital lobe
-Auditory cortex in the temporal lobe
iii. Association Areas
-Electrical probing does not elicit an observable response
-No neat mapping ability
-Frontal Lobes-Enable judgment, planning, and processing of new memories
-Parietal Lobes-Mathematical and spatial reasoning
-Temporal Lobes-Facial recognition
-Avoid Phrenology-type thinking
C. Language
-Broca’s Area-Controls language expression-Directs muscle movement involved in speech
-Wernicke’s Area-Controls language reception-Language comprehension and expression
-Angular Gyrus-When damaged, a person can speak and understand, but will be unable to read aloud
D. The Brain’s Plasticity
-The brains ability to change over time
-Constraint-induced therapy
-Neurogenesis and stem cell research
IV. Our Divided Brain
-Is the left hemisphere more important?
-Reading, writing, arithmetic, reasoning, and understanding
-Left brained vs Right brained
A. Splitting the Brain
-To eliminate seizures, the corpus callosum is severed
-Surprisingly, most split brain patients are “normal” after the procedure
V. Right-Left Differences in the Intact Brain
-Hemispheric specialization
VI. The Brain and Consciousness
-How do neurons firing in succession crate awareness of taste, pain, emotions?
A. Cognitive Neuroscience
-The study of brain activity linked with cognition
B. Dual Processing
-The principle that information is simultaneously processed on separate conscious and unconscious tracks
-Conscious (explicit) vs Unconscious (implicit) memories
