Transcript Learning

Biological Bases of
Mental Life & Behavior
Psychology
• Involves the systematic examination of thoughts
and behavior
• Examination of thoughts and behaviors requires
that something happens
– We think about something
– We do something
• The neuron is the basic component of all thought
and behavior
Neuron
• Fundamental unit of the nervous system
• Thinking and doing transpire through the
connection of multiple neurons
• Estimates range from 10 billion to 100 billion
neurons in the brain alone
• Lack of neuro activity is the definition of death
Neuron
• Sensory (afferent) Neurons
– Transmit information from the sensory cells to the brain
• Motor (efferent) Neurons
– Transmit information from the brain to the organs and
muscles
• Interneurons
– Pass information between the various sensory and
motor neurons
Neurons
• Dendrites
– Numerous dendrites extend
out from the cell body and
collect input
• Cell Body
– Processes input from
dendrites
• Axon
– Sends information forward
through the axon to the next
neuron
Neuron
• Myelin Sheath
– A coating of lipids (fat), derived from glial
cells, that surrounds most axons
– Facilitates transmission of data
– Multiple Scelerosis and Lou Gehrig’s disease
involve demyelization of axons
• Terminal Buttons
– End of axon
– Transmit signal to the next neuron
Triggering a Neuron
• Resting Potential
– A neuron is polarized when no action underway
– Sodium and potassium ions in balance
• Action Potential
– Depolarization
• Influx of + charged sodium ions
• Neuron more likely to fire
– Hyperpolarization
• Outflow of + charged potassium ions
• Neuron less likely to fire
Triggering a Neuron
• Graded Potential
– Brief voltages that travel down dendrites
– Most frequent form of psychological processes
– Create new information at the cellular level by allowing
the cell to integrate signals from multiple sources that
are connecting through various dendrites
• Action Potentials (Nerve Impulse)
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Triggers a cell body into action
All or none event
It triggers the neuron into action
Passes along already created information
Communication between
Neurons
• Synapse
– The bridge (connection)
between the axon of one
neuron and the dendrite of
the next neuron
• Presynaptic neuronneuron sending signal
• Postsynaptic neuronneuron receiving signal
• Synaptic Cleft
– Actual connection point
between axon and dendrite
Neurotransmitters
• Synaptic Vesicles
– Small sacs within terminal buttons that contain
the chemical neurotransmitters
• Neurotransmitters
– Chemicals that carry the signal from one
neuron to another
– When neuron fires the chemicals go into the
synaptic cleft
Neurotransmitters
• Once in the synaptic cleft, some of the
neurotransmitters bind with neurotransmitters
from the connected dendrite
• Excitatory Neurotransmitters increase action
potential
• Inhibitory neurotransmitters decrease action
potential
Types of Neurotransmitters
• At least 75 different neurotransmitters
• Glutamate
– Excites neurons
• GABA
– Inhibits neurons in the brain
• Gylcene
– Inhibits neurons in spinal cord
• Dopamine
– Emotional arousal, pleasure, voluntary movement, attention
Types of Neurotransmitters
• Serotonin
– Sleep and emotional arousal, aggression, pair
regulation, mood
• Acetylcholine
– Learning and memory
• Endorphins and Enkephalins
– Pain relief and elevation of mood
• Epinephrine and norepinephrine
– Emotional arousal, anxiety, and fear
Endocrine System
• A collection of glands that secrete hormones
(signals) directly into the blood stream
• A second system, similar to the nervous
system, for intercellular communication
• Able to simultaneously stimulate numerous
cells
Endocrine System
• Pituitary Gland
– Master Gland
– Hormones it releases stimulate and regulate
other glands
• Thyroid Gland
– Releases hormones involved with growth and
metabolism
– Impacts energy level and mood
Endocrine System
• Adrenal Glands
– Release adrenalin during emergencies
– Prepares one for fight or flight
• Gonads
– Influence sexual development and behavior
– Testosterone in males
– Estrogens in females
Nervous System
• Central Nervous System (CNS)
– Brain and Spinal Cord
• Peripheral Nervous System (PNS)
– Neurons throughout the rest of the body that transmit
signals to and from the CNS
– Afferent Neurons send signals from the PNS to the
CNS
– Efferent Neurons send signals from the CNS to the PNS
Somatic Nervous System
• Intentional actions
– Regulates voluntary actions such as turning
your head or standing up
• Also regulates automatic behaviors such as
balancing yourself on a set of skis
Autonomic Nervous System
Automatic body functions such as heart
function:
• Sympathetic Nervous System
– Responds to threats
– Increases heart rate, stops digestion, etc.
• Parasympathetic Nervous System
– Regulates routine duties such as secreting salvia
Central Nervous System
• Spinal Cord
– Collects sensory information from the PNS and
transmits it to the brain
– Transmits instructions from the brain to the
PNS (motor signals)
• Brain
– CPU of the body
Spinal Cord
• Segmented
– Each segment interfaces with a different part of
the body
• Spinal Nerves
– 31 pairs of sensory and motor neuron bundles
to transmit and receive data to/from CNS
Spinal Cord
Paralysis
– Injury to the spinal cord
– Prevents data from flowing to/from the brain
– Results in inability to move the parts of the
body that are below the spinal injury
Brain
• Hindbrain
– Directly above and linked to the spinal cord
– Most primitive, yet essential, part of our nervous
system
– Includes:
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Medulla Oblongata
Cerebellum
Parts of the reticular formation
Pons
Brain
Medulla Oblongata
– Extension of spinal cord that links it to the brain
– Nerve bundles cross from one side of the body to the
opposite side of the brain
– Weakness in left side of the body suggests a problem on
the right side of the brain
– Regulates heartbeat, circulation, respiration
Brain
• Reticular Activating System (RAS)
– Network of neurons that extends from medulla
to the upper end of the midbrain
– Sends signals to many parts of the CNS
– Maintain consciousness, regulates arousal
levels and modulates activity of neurons
throughout the CNS
Brain
• Cerebellum
– Involved with motor learning and movement,
balance and posture
– When impacted our movements are not well
coordinated
Midbrain
• Tectum
– Vision and hearing
• Tegmentum
– Orienting body and eyes towards a sensory
stimuli
Brain
• Subcortical Forebrain
– Complex sensory, emotional, cognitive and
behavioral processes
– Consists of the
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Hypothalamus
Thalamus
Limbic System
Basal Ganglia
Brain
• Hypothalamus
– Eating, sleeping, sexual activity, emotional experience
– Key link between the nervous system and the endocrine
system
– Activates the pituitary during stressful events
• Thalamus
– Process sensory data and transmit it to higher brain
centers
– Also regulates signals (more/less important)
Brain
• Amygdala
– Learning and remembering emotionally significant
events
– Involved in recognizing emotions in other people (fear
in others)
• Hippocampus
– Involved in storing information in our memory
• Basal Ganglia
– Movement and judgments requiring minimal conscious
thought
Brain
• Cerebral Cortex
– 80% of brain mass
– Allows flexible construction of voluntary movements
– Subtle discrimination among complex sensory patters
– Enables symbolic thinking (foundation of human
thought)
Brain
• Cerebral hemispheres
– Two halves of the cortex that are divided by a longitudinal fissure
– The corpus callosum connects the two hemispheres
– Left fontal and temporal lobes play a more important role in
speech and language than the right side counterpart
• Occipital Lobes
– Vision
• Parietal Lobes
– Touch
Brain
• Frontal Lobes
– Movement, planning, abstract thinking, memory, some
aspects of personality
– Motor cortex initiates voluntary movements
– May be site of neural dysfunction that underlies
schizophrenia
• Temporal Lobes
– Hearing, language, and recognizing objects by sight
Left Brain—Right Brain
• Cerebral Lateralization
– Some division of labor does exist between both sides of
the brain
• Left Brain
– Language, logic, complex behavior and consciousness
(analytical)
• Right Brain
– Nonlinguistic functions such as visual images, music,
feeling
Genetics
• Genes
– DNA (deoxyribonucleic acid)
– Two alleles in each gene (one from each parent)
• Dominant
• Recessive
• Genotype
– Our genetic blueprint
Genetics
• Degree of relatedness
– The probability of sharing genes with relatives
• Twins
– Monozygotic = Same sperm and (one) egg
– Dizygotic= Two sperm and two eggs
• Heritability Coefficient
– Degree of variation in a trait across individuals
Evolution
• Traits common to a particular species that
contribute to the survival and reproductive
fitness of members of that species
• Charles Darwin
Genetic Engineering
• Deliberate effort to influence genetic code
of a given member of a species
• Cloning