This document discusses the biological bases of mental life and behavior. It covers neurons, neurotransmitters, the nervous system, cerebral lateralization, and behavioral genetics. Neurons transmit information via dendrites, cell bodies, and axons. There are three types of neurons. Neurotransmitters are stored in vesicles and released at synapses to transmit signals between neurons. The nervous system includes the brain and spinal cord. Cerebral lateralization refers to specialization of function in the left and right hemispheres of the brain. Behavioral genetics examines the influence of genes on psychological traits using twin studies.

1. “Biological Bases of
Mental Life and
Behavior”

2. BIOLOGICAL BASES OF MENTAL LIFE AND BEHAVIOR
 Neurons
 Neurotransmitters
 The Nervous system
 Cerebral lateralization
 Behavioral genetics

3. NEURONS
Components of the Neuron
•Dendrites: receive information
•Cell body
•Axon
Myelin insulates the nerve cell, speeds up conduction of
nerve messages
Terminal buttons of the axon release transmitter

4.  Neuron: A cell that specializes in the transfer of
information within the nervous system
 Three classes of neurons:
 Sensory: Transmit information from sensory receptors to
the brain (afferent)
 Motor: Transmit commands from the brain to the muscles
and glands of the body (efferent)
 Interneuron's: Interconnect neurons

5. NEUROTRANSMITTERS
 Neurotransmitters are chemicals
 Stored within vesicles of the presynaptic cell
 Released in response to the action potential
sweeping along the presynaptic membrane
 Transmitter molecules diffuse across the
synaptic cleft and bind to postsynaptic
receptors
 Receptor binding opens or closes ion channels:
 NA channel opening: Depolarizes the
membrane
 K+ channel opening: Hyperpolarizes the
membrane

6. THE NERVOUS SYSTEM

7. Functions of cerebral cortex:
>provides for flexible control of patterns of movement
>permits subtle discrimination among complex
sensory patterns
>makes possible symbolic thinking
>symbolic thought is the foundation of human
thought and language
Cerebral cortex

8. Cerebral Lateralization
 The structures of the cortex and sub-cortex appear to specialize
in function:
 Hemispheric Specialization
 Left hemisphere is dominant for language, logic, and complex
motor behavior.
 Right hemisphere is dominant for non-linguistic functions
including recognition of faces, places, and sounds (music)
 The hemispheric specializations are evident from studies of
 Damage to one hemisphere (I.e. Broca’s area)
 Split-brain subjects
 Gender differences in brain lateralization
 Issue is whether the brains of males and females may be
organized differently and whether such organization might have
functional significance

9.  Lateralization is the idea that the two
halves of the brain's cerebral cortex -- left
and right -- execute different functions. The
lateralization theory -- developed by Nobel-
prize-winners Roger Sperry and Robert
Ornstein -- helps us to understand our
behavior, our personality, our creativity,
and our ability to use the proper mode of
thinking when performing particular tasks.
Lateralization

10. Behavioral genetics
 Behavioral genetics is concerned with the influence of
genes on psychological function
 Genotype: Genetic structure (DNA located on chromosomes)
 Phenotype: Observable psychological function
 Relatedness is the probability of sharing a gene with
parents and others
 Heritability: Quantifies the extent to which variations
in a trait across persons can be accounted for by
genetic variation

11. BEHAVIORAL GENETICS: METHODS
 The primary method for studying heritability is the
twin study.
 Identical and fraternal twins raised together and
apart.
 If identical twins raised apart are more similar than
fraternal twins raised apart, then the increased
similarity is assumed to be due to increased genetic
similarity.