PSY 3044 - LECTURES > Biological Foundations, Neuroscience, Neuropsychology

I. BIOPSYCHOLOGY, A LITTLE HISTORY, and the EVOLUTIONARY PERSPECTIVE

A. Consciousness, life, mind, etc. has historically been associated with the Heart or the Head

1) In ancient Egypt, the heart and other organs mummified with Pharoahs, the brain was tossed out

2) In ancient Greece, some philosophers believed in a heart-centered life force/consciousness, for example Aristotle, who reasoned that the heart moves, has heat, is necessary for life; he thought the brain was a "radiator", set up to cool the blood by its convoluted structure and system of blood vessels

3) In ancient Rome, the physician Hippocrates credited the brain with feelings, mind, and consciousness

4) 17th Cent. - Descartes believes the brain directs the muscles by pneumatic (pressure and fluid) mechanisms

5) 18th Cent. - Galvani shows that electrical stimulation of frog muscles makes it move (biological electricity)

6) 18th Cent. - Later, Loewi shows that fluid taken from around an electrically stimulated frog heart can cause another heart to beat (suggesting the idea of neurochemistry)

B. The Evolutionary Perspective
- Many biopsychologists, comparative psychologists, and neuropsychologists adopt an evolutionary perspective in their approach to studying biological systems related to behavior

- Charles Darwin described natural selection as the process whereby organisms better suited to the enviornment (or changes to it) will more likely survive and reproduce than other, less well adapted
organisms

II. SENSING, PROCESSING, and RESPONDING

A. STIMULUS (Sensory Systems)

Sensing events requires that a stimulus activates a receptor

B. PROCESSING

Processing events takes place in the brain; figuring out the pattern of sensations and
their meaning

C. RESPONSE - (Motor Systems)

Responding to events occurs when the brain sends messages to the muscles

III. The NERVOUS SYSTEM

A. Peripheral nervous system (PNS)

1. Somatic division: Afferent nerves versus efferent nerves

2. Autonomic division

a. Sympathetic division prepares the body for "fight or flight"
- dilation of pupils, increased heart rate, dilation of bronchi (lungs), inhibition of
gastrointestinal system, glucose/glycogen released from liver and routed to muscles

b. Parasympathetic division returns the body to homeostasis
- constriction of pupils, decreases in heart rate, lungs relax, gastroinestinal activity restored,
liver stores excess glucose/glycogen

B. Central nervous system (CNS)

1. Spinal cord

a. Sensory, motor, and interneurons course through the spinal cord

b. Reflexes are automatic responses that occur prior to reaching the brain

c. Afferent sensory neurons bring information into the dorsal portion of spinal cord

2. The brain

a. Hindbrain: Medulla, pons
cerebellum: for posture and coordinating movement

b. Midbrain: Reticular formation coordinates arousal and alertness

Together the hind- and mid-brain are called the brain stem

c. Forebrain

i. Some important structures/areas:
- limbic system: includes hippocampus (memory) and amygdala (emotion)
- hypothalamus: helps regulate temperature, water, other homeostasis mechanisms
- thalamus: gets information from all senses; often called a relay station
- basal ganglia: important for motor control

ii. Cortex: Two hemispheres, four lobes (Frontal, Parietal, Occipital, Temporal)

3. Studying the functions of the brain

a. Early surgical approaches mapped functions through lesion, removal

b. Case study method inferred function from deficit

c. Studies of brain damage shed light on the normal functioning of the brain

d. Stereotaxic surgery gave more precision to studying subcortical regions

e. Electroencephalography (EEG) displays the electrical activity of the brain

IV. METHODS for STUDYING the NERVOUS SYSTEM

A. Neuroanatomy

1. Perfusion
2. Fixation - formaldehyde or derivative
3. Cutting - with microtome
4. Staining - for neuron structures, chemicals
5. Analysis - with light or electron microscope, etc.

B. Neurochemistry - In vivo ("living") or In vitro (basically, in a dish or outside the organism)

C. Neuroimaging

1. Methods to look at brain Structure: CAT, MRI

2. Methods to look at brain Function: PET, fMRI

V. NEURONS: The ELEMENTS of THOUGHT

A. Components of the neuron

1. Cell membrane is a semipermeable boundary

2. Dendrites receive signals from receptors

3. Soma (cell body) performs metabolic processes of the neuron

4. Internal structures in soma: Golgi apparatus (packages neurochemicals into sacs called vesicles), Mitochodria (the power plant of the cell, produces energy; some scientists think it used to be an independent organism that "infected" animal cells millions of years ago); Nucleus (contains all the genetic material, provides the blueprints for the production of proteins, etc. that the cell needs)

5. Axons send signals to other neurons and to muscles and glands

6. Terminal buttons are found at the ends of axonic branches

7. Myelin sheath made by glia cells (oligodendrocytes), a lipid (fatty) covering that speeds transmission by an axon

B. The synapse and neurotransmitters

1. Synapse

a. Terminal button sends a signal

b. Dendrite receives a signal

c. Synaptic cleft is the gap between the two

2. Neurotransmitters

a. Synaptic vesicles hold chemicals to transport signal across the synapse

b. Through excitation or inhibition neurotransmitters activate cells

c. Glutamate, GABA, serotonin (5-HT), dopamine (DA), acetycholine (ACh), endorphins are examples

3. Clearing the synapse

a. Reuptake: returns neurotransmitter to terminal button for reuse/recycle

b. Degradation: neurotransmitter is broken down by enzymes

c. Autoreceptor: signals the neuron to stop release/production of neurotransmitter

4. Neurotransmitters and drug action

a. Agonists enhance the operation of neurotransmitters

i. Prozac (5-HT), L-DOPA (DA), Nicotine (ACh), and Caffeine (Glutamate) are familiar examples

ii. Ritalin is a DA agonist by blocking the reuptake mechanism for DA

b. Antagonists block the operation of neurotransmitters

i. Many poisons (even fictional ones like in the movie "The Rock") can act by inhibiting AChE, acetylcholinersterase, which breaks down ACh

ii. Botulinum toxin and Atropine act by blocking receptors for ACh

c. Neuromodulators have a widespread effect on neurotransmitter release

i. Morphine, opioid peptides are examples

C. The nature of the neural signal

1. Neuron's resting state means more negative ions inside membrane

a. Depolarization or hyperpolarization change the negative charge

IMAGE - DIAGRAM of the ACTION POTENTIAL

2. Depolarization and excitatory synapses

a. Action potential describes neuron's all-or-none firing

b. Refractory period can be absolute or relative

3. Hyperpolarization and inhibitory synapses

VI. The Split-Brain Operation and Neuropsychology

A. Neuropsychology

1. "The Man Who Mistook His Wife for a Hat" (Dr. P) had a disorder known as visual agnosia
(agnosia="failure to know); damage from tumor to occipital and parietal lobes; couldn't recognize objects, although he could see the details (color, shape, motion, etc.)

2. "The Lost Mariner" (Mr. G) had Korsakoff's syndrome due to damage of the mammilary bodies from severe alcoholism; he was unable to form new memories (the mammilary bodies have extensive connections with the hippocampus, implicated in memory formation)

B. Severing the corpus callosum eliminates communication between the hemispheres

1. In the case of severe epilepsy this provides some relief

2. "Split-brain patients" also allow us to understand cerebral functions

C. Brain asymmetries

1. Structural, chemical, or functional differences between the hemispheres

a. Qualities associated with Right Hem = Emotion in speech, Spatial, Holistic
xxxxxxxxxxxxxxxxxxxxxxxxLeft Hem = xLanguage, Logic, Sequential Tasks
b. Aphasias: Language deficits

c. Apraxias: Deficits involving nonverbal skills