INTRODUCTION TO PSYCHOLOGY
Week 3: Brain and Behaviour
✓ The entire nervous system is made of neurons
✓ There are 5 main parts of the neuron
i. cell body- central area that performs neurons basic activities; translate received message
ii. dendrite- smaller passageways for transmission receive messages; serves as input part of neuron
iii. axon- a fiber that carries transmission toward of neurons; send message. Covered by myelin sheath produced by glial cells; deterioration leads to Multiple Sclerosis
iv. Axon terminal\terminal button- to dendrite-if another cell. Contains little areas called terminal button does not touch the dendrite but has a synaptic gap. In terminal button are giant vesicles containing neurotransmitters substances about 70 discovered
v. synapse- slave to be crossed between axon terminal and dendrite
✓ The 3 main types of neurons:
i. Interneurons- also called connector/ relay neurons for communication between sensory and motor neurons We also discuss several other topics like How do you know if its polar or nonpolar?
ii. Sensory neurons- neurons in the senses, they detect stimuli and carry information from sensory receptors to the brain
iii. Motor neurons- go to muscles carry info from brain to muscles/ brain stem to muscles and glands
There are 600 synapses at the terminal button of one neuron at birth as we grow that number increases up to 35,000
✓ All-or-None response
• Neurons are either firing of not firing
• When neuron is at rest\not firing is called resting potential • When the electrical charge reaches a threshold, neuron begins to fire. This is called action potential
• Refractory period, waiting time before next firing not get control • RESTING POTENTIAL ACTION POTENTIAL REFRACTORY PERIOD
✓ Major Structure of The Nervous System
A. Central Nervous System: If you want to learn more check out What were some new changes in the 2015 dgs?
II. Spinal cord
B. Peripheral Nervous System:
I. Somatic/ Voluntary Nervous System: connects CNS to parts of the body under our control spreads throughout body
II. Autonomic/ Involuntary Nervous System: connects CNS to parts of the body, centered around where organs are. It is divided into:
i. SYMPATHETIC NERVOUS SYSTEM - for turning up; involved in fight/ flight: a physiological response in period of stress
ii. PARASYMPATHETIC NERVOUS SYSTEM - for turning down for maintaining body processes
for regulating body temperature at 98.6 Fahrenheit in process called homeostasis
Overall, nervous system works by
Input Process Output
✓ NEURONAL COMMUNICATION
o are chemical messengers that are contained in synaptic vesicles o they fit into receptors by Lock and key hypothesis
o when not accepted by the receptors of the next neuron undergo reuptake If you want to learn more check out What are the two kinds of electric charges?
o Some important neurotransmitters and their effects Don't forget about the age old question of What do you call the value that summarizes the parameter?
a) Endorphins- reduces pain, increases pleasure (runners high). b) Dopamine- influences brain's reward system and movement, implicated in schizophrenia, Parkinson's disease, ADHD,
dopamine, Alzheimer's disease
c) Serotonin- involved with sleep cycle, possibly mood and appetite. Selective Serotonin Release Inhibitors (SSRIs) are antagonists used to decrease the amount of serotonin that is released
d) Epinephrine also known as adrenaline- involved in fight/ flight speeds up heart rate, organs speeding up. Activate body's
natural stress responses. Further increased by caffeine\
e) Histamine- influences immune system
f) Acetylcholine- helps muscles movement
g) Gamma Aminobutyric Acid (GABA)- helps to control anxiety
Antagonists- negatively affect activity of neurotransmitter e.g. blue light inhibits serotonin
Agonists- have the same impact as neurotransmitters e.g. nicotine, speeds up heart rate
✓ The Brain
• made up of 100 billion interneurons.
• Human brains are larger on top and in front than in other animals. This is due to evolution
• Localization: the idea that certain areas of the brain are responsible for certain actions We also discuss several other topics like How are impressions different from ideas?
✓ Parts of the brain
A. Cerebrum/ Forebrain
• front upper part of the brain; responsible for distinctly human abilities- talking, reasoning, etc.
• Cerebral cortex- outer layer of cerebrum for sensory processing • 2 hemispheres: connected by a bundle of neurons called corpus callosum If you want to learn more check out What do you call the step by step process of a reaction?
o Left hemisphere: language, thinking, memory
o Right hemisphere: spatial recognition, facial recognition, music
In split brain surgeries, there is severance of corpus callosum to treat severe epileptic conditions
• Parts of the cerebrum
a) Frontal Lobe
• Located just behind the forehead
• Prefrontal region makes up 29% of cerebral cortex in
humans- for executive control of tasks
• Contains the motor cortex which is involved in voluntary movement
• Broca's area- upper left area, for language production.
Broca’s aphasia aka expressive aphasia results in difficulty in producing speech
• Responsible for higher order functioning e.g. Speaking, critical thinking, distinguishes us from other primates
b) Parietal Lobe
• Located in top and back of the head.
• Responsible for touch and perception sensation
• Contains the somatosensory cortex
c) Temporal Lobe
• Lower middle of brain
• hearing\ what we see
• Wernicke's area is for understanding and recognizing speech. • Wernicke’s Aphasia aka receptive aphasia occurs when there is damage to this area
• communicates with parietal lobe
d) Occipital Lobe
• Located in the back of the brain
B. Brain stem
• connects and supports the brain and spinal cord to ensure messages from the brain reach the spinal cord
• responsible for essential functions of life: breathing, beating of the heart as well as bodily functions such as swallowing, sneezing, vomiting
• contains the reticular activating system involved in sleeping, waking, alertness, attention
• contains pons and medulla
• involved in balance and coordination
• occupies 10% of space in brain but contains half the total number of neurons
D. Limbic system:
• Involved with Basal ganglia in movement
• near the center of the brain.
• Surrounds the thalamus: the brain’s main sensory processing center
• consists of
• regulates bodily functions by influencing the pituitary gland • Also has significant effect on autonomic nervous system • Helps maintain homeostasis
b) Amygdala: connected to emotions especially fear
• involved in spatial and long-term memory
• damage to the hippocampus results in amnesia
• 2 types of amnesia
o Retrograde amnesia- inability to recall long term memories o Anterograde amnesia- inability to form new memories.
NOTE: the amygdala is close to the hippocampus that explains why we remember tragic events.
stress can damage hippocampus
✓ Brain Plasticity
• the ability of the brain to adapt structure and function to damage or experience.
• There are 3 types of brain plasticity:
i. Plasticity after brain damage
ii. Plasticity after life experience
iii. Plasticity after psychotherapy
NOTE: One factor that affects plasticity is age Stem cells can be generated during plasticity neurogenesis: manufacture of neurons that didn't exist before.