Introducton
Mind-brain (body) problem: how mind relates to brain act.
No convincing expl for consc.
Biological psy: physiological, evolutonary devel mechanisms of beh exp.
Neuroscience: beh anatomy chemistry.
Microscopic level brain: neurons (convey messages) glia (smaller, not convey over great distance).
3 general points:
1. Percepton occurs in brain. Feel in brain not in body.
2. Mental act brain act inseparable = monism – universe consists of 1 type being. (opposite:
dualism).
3. Cautous what is expl what not. Not always tell why. Correlaton isn’t causaton.
Expl of beh:
Physiological: act of brain other organs. Chemical reactons, etc.
Ontogenetc: how structure or beh devel incl inl: genes, nutriton, exp, etc.
Evolutonary: history of structurebbeh. Modifcatons. Beh similarites among related species.
Functonal: why structure or beh evolved as it did. Genetc drif (by accident) or advantage in
survival.
Studying nonhumans:
Underlying mechanisms of beh similar across species easier to study in nonhuman species.
Resemble chemistry anatomy (brain, etc.). Squid nerves (tccer in nonhumans, easier to
study in htem).
For animals’ sace own
Sheds light on human evoluton
Legal or ethical restrictons prevent study on humans. Bv insertng electrodes in braincells →
relsh brain act beh.
Minimalists tolerate certain cinds of animal research but prohibit others.
Reducton animal numbers, replacement refnement (reduce pain discomfort).
H1 Nerve cells and nerve impulses
1.1 The cells of the nervous system
Nervous syst: neurons (85 billion) glia.
Charles Sherrington Santago Ramón Cajal founders neuroscience. Cajal combined anatomy
research wb illustratng.
Surface of cell = membrane. Most chemicals cannot corss membrane → protein channels control
low chemicals.
All animal cells nucleus (= where DNA stored in cell) except for red blood cells.
Mitochondrion performs metabolic act, providing energy.
Ribosomes = place where cells synthesizes new protein molecules (building material). Some atached
to endoplasmic retculum (ER) → transports proteins to other locatons.
Tiniest neurons lacc axons well-defned dendrites.
Motor neuron receives excitaton through dendrites conducts impulses along axon to muscle.
Sensory neuron sensitve to partcular type of stmulaton.
Dendrites = branching fbers. Lined wb specialized synaptc receptors. Receive info from other
neurons. More surface, more info receive.
Dendritc spines = outgrowths incr surface for synapses.
1
, Cell bodybsoma contains nucleus, ribosomes, mitochondria. Most of neuron’s metabolic worc.
Covered in synapses on surface.
Axon conveys impulse to other neurons etc. Can be 1m (spinal cord to feet). Covered in myelin
sheath wb interruptons (nodes of Ranvier). Invertebrate axons no myelin sheath.
Branches axon form presynaptc terminal at end. Release chemicals that cross between neurons.
Each neuron 1 axon more dendrites, but axon has branches.
Afferent axon brings info in structure.
Efferent axon carries info away.
Sensory neuron afferent from nervous syst.
Motor neuron efferent from nervous syst.
Interneuronbintrinsic neuron = dendrites axon contains wbin single structure. Bv neuron in
thalamus has axon dendrites in thalamus.
Neurons vary in size, shape funct. Shape determines connectons wb other cells fucnt.
Glia more than neurons.
Astrocytes wrap around presynaptc terminals axons. Shield from chemicals. Tacing up ions
released by axons releasing bacc. Help synchronize act axons. Guide formaton
eliminaton synapses. Remove waste material. Dilate blood vessels when heightened act in
brain area.
Tripartte synapse hypothesis: tp axon releases chemicals that cause neighboring astrocyte
to release chemicals → magnifyingbmodifying message to next neuron.
Microglia: part of immune syst: remove waste material, viruses fungi from brain.
Proliferate afer brain damage. Contribute to learning (remove weacest synapses).
Oligodendrocytes Schwann cells build myelin sheath. Supply axon wb nutrients.
Redial glia: guide migratng neurons during embryonic devel. Later differentate into neurons,
astrocytes oligodendrocytes.
Many chemicals cannot cross from blood to brain: blood-brain barrier.
Cells expose virus through membrane → immune syst cells identfy it, cill it wb cell.
Some viruses cross blood-brain barrier. Can have fatal consequences. Microglia effectve against
viruses. Fight virus wbout cilling neuron. May only control not cill.
Blood-brain barrier on endothelial cells that form wall of capillaries. Keep out all chemicals. Special
mechanisms to get chemicals needed.
Small, uncharged molecules, molecules that dissolve in fat.
Other: actve transport. Expends energy.
Keep out many medicatons.
Carbon hydrates fats for nutriton cell.
Vertebrate neurons dep on glucose. Can use cetones lactate. Nutrient that can cross blood-brain
barrier in large quanttes.
Problem: inability to use glucose. Need vit B1 (thiamine).
1.2 The nerve impulse
Strength impulse from senses decay rapidly because body made of water carbon. Short people feel
feet more strongly than tall people.
Axon regenerates: impulse → doesn’t weac off that fast.
Only in vision need to cnow whether one stmulus is before other. Not in touch.
Membrane at rest: electrical gradient = polarizaton = diff in charge in- outside cell. Inside slightly
neg. Restng potental. --70mV.
Membrane selectvely permeable. When at rest: NabK channels closed → stmulaton needed to
open.
2
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