Chapter 2 Notes: The Biology of Mind
Chapter 2: The Biology of Mind
Neurons
- nerve cells comprised of a cell body and fibers
- Two kinds of fibers: $2$ kinds
- Dendrites: bushy fibers that receive information
- Axons: long fibers that send information along to other neurons
Action Potential
- a neural impulse or electrical charge
- it travels down an axon
- it can be slow or fast
- Signals can be:
- Excitatory: speeds up neural activity
- Inhibitory: slows down neural activity
Threshold
- the minimum level of stimulation needed for neurons to start communicating
- If this is exceeded, the action potential is activated and information is sent to other parts of the body
- All-or-Nothing Response: it either happens or it doesn’t
Synapse
- place where two neurons meet
- Synaptic Gap: space which separates sending and receiving neurons
- Neurotransmitters: chemical messengers; $>100$ types
- Reuptake: when the sending neuron reabsorbs all excess neurotransmitters
Types of Neurons
- $3$ types:
- a) Sensory neurons
- b) Motor neurons
- c) Interneurons
- Sensory neurons: millions; carry info from body’s tissues and sensory receptors to the brain and spinal cord (CNS)
- Motor neurons: millions; used by the CNS to get info to the body’s tissue
- Interneurons: billions; receive, analyze, and decide what to do; communicate between sensory and motor neurons; higher complexity in interneurons
Neural Communication Roles
- Sensory Neurons: receive info from sensory receptors and send to CNS
- Interneurons: inside CNS; decide what to do with the info
- Motor Neurons: carry decisions to body’s tissue; trigger responses
The Nervous System
- two kinds:
- 1) Central Nervous System (CNS): Brain and Spinal Cord
- 2) Peripheral Nervous System (PNS): Somatic and Autonomic
Peripheral Nervous System (PNS)
- has two parts:
- 1) Somatic: voluntary control of skeletal muscles
- 2) Autonomic: controls glands and muscles of internal organs
Autonomic Nervous System
- has two parts:
- 1) Sympathetic: arouses the body if it senses danger
- 2) Parasympathetic: calms the body after danger is passed
- uses Epinephrine (aka Adrenaline):
- both a hormone and neurotransmitter
- acts mainly as a hormone
- helps prepare for Fight or Flight
- main effect is on the heart
- Norepinephrine:
- both a hormone and neurotransmitter
- helps transmit info across nerve endings
- main effect is on blood vessels
- provides energy to brain and body to take action
The Endocrine System
- Hormones: chemical messengers
- Endocrine System: slow, like snail mail
- Nervous System: fast, like email
- Which lasts longer? Endocrine messages; slow to arrive but once there, last longer
- Pituitary Gland: the Master endocrine gland
- effects growth
- controlled by the hypothalamus
Four Happy Neurotransmitters
- 1) Serotonin: long-lasting feeling of well being
- 2) Dopamine: temporary pleasure
- 3) Endorphins: pleasure in response to discomfort or pain
- 4) Oxytocin: pleasure from affection and connection; the love hormone
Brainstem
- has three parts:
- 1) Medulla: located where brainstem enters the skull; controls heartbeat and breathing
- 2) Thalamus: located on top of brainstem; brains’ switchboard for all sensory info
- 3) Reticular Formation: inside the brainstem, filters the info it receives and sends to other parts of the brain
Cerebellum
- extends from back of the brainstem
- baseball-sized; two halves look like mini-brain
- processes sensory info; helps with movement
Limbic System
- one of the brain’s oldest parts
- emotions and memory formation
- is between brain’s two halves
Amygdala
- influences aggression and fear
- processes emotional memories
Hypothalamus
- helps maintain a balanced state
- helps regulate all body systems: hunger, thirst, temperature, etc.
Cerebral Cortex
- thin layer of interconnected neural cells
- larger mammals have larger cerebral cortexes; greater capacity to think and learn
- Four parts of Cerebral Cortex: Frontal, Parietal, Occipital, Temporal
Frontal Lobes
- behind your forehead
- thinking, planning, judging
Parietal Lobes
- top and to the rear of brain
- touch and body position
Occipital Lobes
- back of head
- deals with visual information
Temporal Lobes
- just above ears
- deals with auditory information
Lobes of the Brain
- Frontal lobe
- Temporal lobe
- Parietal lobe
- Occipital lobe
Neurogenesis
- Creates new neurons; how?
- sleep, exercise, stimulating environments
Corpus Callosum
- Fibers connecting two halves
- Can cut fibers and still live
- Referred to as split brain
Left and Right Brain Differences
- Left Brain Functions:
- Verbal processing, speech, grammar
- Logical, sequential, rational, analytical
- Objective, calculation
- Left brain looks at the details, the pieces
- Right Brain Functions:
- Uses nonverbal information
- Creative, random, intuitive, perceptive
- Visual recognition
- Emotions
- Subjective, holistic
- Right brain looks at the big picture
Functions of Left and Right Brain
- LEFT-BRAIN FUNCTIONS
- Analytic thought
- Logic
- Language
- Reasoning
- Science and math
- Written
- Numbers skills
- Right-hand control
- RIGHT-BRAIN FUNCTIONS
- Art awareness
- Creativity
- Imagination
- Intuition
- Insight
- Holistic thought
- Music awareness
- 3-D forms
- Left-hand control
Plasticity
- Can compensate for damaged brain areas
- Re-wires the brain so can still perform
- Reorganizes existing brain connections
- Younger brains are more plastic; therefore can heal more completely
Broca’s Area
- Associated with language production
- Connects thoughts and language abilities
- Located in left frontal, temporal lobe
Wernicke’s Area
- Associated with language comprehension
- Helps us understand the meaning of words
- Located in posterior frontal, temporal lobe
7 Ways to a Healthy Brain (Dr. Daniel Amen)
- Protect your brain (helmet)
- Avoid Toxic substances
- Get enough sleep
- Healthy diet
- Take multi-vitamin and fish oil
- Exercise at least $3$ times per week
- Work brain in a new way, $15$ mins per day