Chapter 2 Psychological Methods. 2 Chapter 2 Chapter 2: Section 1 Conducting Research.
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Transcript of Chapter 2
The Biology of Behavior
Chapter 2
Overview: What We Have in Mind
Building blocks of mind: ____________ and how they communicate (neurotransmitters)
Systems that build the mind: Functions of Parts of the ___________________
Supporting player: the slower-communicating ___________________(hormones)
Tools for examining the brain and its activities More primitive and advanced brain structures
Interesting Figures in Neuroscience
• Franz Gall-1758-1828
• Phrenology
• Santiago Ramon y Cajal
1852-1934
Neurons and Neuronal Communication:The Structure of a Neuron
There are billions of neurons (nerve cells) throughout the body.
________________________:a neural impulse that travels down an
axon like a waveJust as “the wave” can flow to the right in a stadium even though the people only move up and down, a wave moves down an axon although it is only made up of ion exchanges moving in and out.
The neuron
receives signals
from other neurons; some are telling it to
fire and some are telling it
not to fire.
• When the threshold is reached, the action potential starts moving.
• Like a gun, it either fires or it doesn’t; more stimulation does nothing.
• This is known as the “all-or-none” response.
The action
potential travels
down the axon
from the cell body
to the terminal
branches.
The signal is transmitted to another cell. However, the
message must find a way to cross a gap
between cells. This gap is
also called the synapse.
How neurons communicate(with each other):
When does the cell send the action potential? When it reaches a threshold.
The threshold is reached when excitatory (“Fire!”) signals outweigh the inhibitory (“Don’t fire!”) signals by a certain amount.
The synapse is also known as the “synaptic junction” or “synaptic gap.”
The SynapseThe synapse is a junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron.
Neurotransmitters
Neurotransmitters are chemicals used to send a signal across the synaptic gap.
Reuptake: Recycling Neurotransmitters [NTs]
Reuptake: After the neurotransmitters stimulate the receptors on the receiving neuron, the chemicals are taken back up into the sending neuron to be used again.
Seeing all the Steps TogetherNeural Communication:
Some Neurotransmitters and Their FunctionsNeurotransmitter Function Problems Caused by Imbalances
Roles of Different Neurotransmitters
Serotonin Affects mood, hunger, sleep, and arousal
Undersupply linked to depression; some antidepressant drugs raise serotonin levels
DopamineInfluences movement, learning, attention, and emotion
Oversupply linked to schizophrenia; undersupply linked to tremors and decreased mobility in Parkinson’s disease and ADHD
Acetylcholine (ACh)
Enables muscle action, learning, and memory
ACh-producing neurons deteriorate as Alzheimer’s disease progresses
Norepinephrine Helps control alertness and arousal
Undersupply can depress mood and cause ADHD-like attention problems
GABA gamma-aminobutyric acid
A major inhibitory neurotransmitter
Undersupply linked to seizures, tremors, and insomnia
GlutamateA major excitatory neurotransmitter; involved in memory
Oversupply can overstimulate the brain, producing migraines or seizures; this is why some people avoid MSG (monosodium glutamate) in food
__________ pathways
Networks of neurons that communicate with serotonin help regulate mood.
Networks of neurons that communicate with dopamine are involved in focusing attention and controlling movement.
____________ pathways
Divisions of the Nervous System
The Inner and Outer Parts of the Nervous System
The Central Nervous System (CNS), the brain and spinal cord, is the body’s decisionmaker.
The Peripheral Nervous System (CNS), gathers information from the body and sends CNS decisions out to the body.
Types of NeuronsSensory
neurons carry messages IN
from the body’s tissues and
sensory receptors to the
CNS for processing.
Motor neurons carry instructions
OUT from the CNS out to the body’s tissues. Interneurons (in the
brain and spinal cord) process information between the sensory
input and motor output.
The Peripheral Nervous System
The ___________
Nervous System:
The sympathetic NS arouses
(fight-or-flight)
The parasympathetic
NS calms(rest and digest)
The ________________ System
The endocrine system: a set of glands that produce chemical messengers called hormones.
The Body’s “Slow but Sure” Endocrine Message System The endocrine system sends
molecules as messages, just like the nervous system, but it sends them through the bloodstream instead of across synapses.
These molecules, called hormones, are produced in various glands around the body.
The messages go to the brain and other tissues.
Pituitary gland
The pituitary gland is the “master gland” of the endocrine system.
It is controlled through the nervous system by the nearby brain area--the hypothalamus.
The pituitary gland produces hormones that regulate other glands.
The Brainstem: Pons and Medulla
The Base of the Brainstem: The Medulla
The medulla controls the most basic functions such as ___________________________
Someone with total brain damage above the medulla could still breathe independently, but someone with damage in this area could not.
The Thalamus The thalamus is the
“sensory switchboard” or “router”: All sensory messages, except smell, are routed through the thalamus on the way to the cortex (outer brain).
These messages cross over from one side of the body to the opposite side of the brain.
The crossover
The cerebellum helps coordinate voluntary movement such as playing a sport.
Cerebellum (“little brain”)
The cerebellum has many other functions, including enabling nonverbal learning and memory.
emotions such as fear and aggression.
basic drives such as hunger and sex.
the formation of episodic memories.
The hippocampus (“seahorse”) processes conscious, episodic
memories. works with the amygdala to
form emotionally charged memories.
The Amygdala (“almond”) consists of two lima bean- sized
neural clusters. helps process emotions,
especially fear and aggression.
The Limbic (“Border”) SystemThe limbic system coordinates:
The Amygdala: Enabling two different responses to threat
Electrical stimulation of one area of a cat’s amygdala provokes _________________ reactions.
If you stimulate a different part of the amygdala and put the cat in a cage with a mouse, the cat will cower in terror.
lies below (“hypo”) the thalamus.
regulates body temperature and ensures adequate food and water intake (homeostasis), and is involved in sex drive.
directs the endocrine system via messages to the pituitary gland.
The Hypothalamus:Thalamus
Riddle: Why did the rat cross the grid? Why did the rat want to get to the other side?
The Hypothalamus as a Reward Center
Pushing the pedal that stimulated the electrode placed in the hypothalamus was much more rewarding than food pellets.
Review of Brain Structures
Higher Brain, Split BrainTopics for your cortex to process:
Cerebral Cortex Structure: The Lobes
The motor and sensory strips and association areas
Brain Plasticity Functioning of he
right and left hemispheres from cases of the divided and intact brains
The Cerebral Cortex:
300 billion synaptic connections
The brain has left and right hemispheres
The outer grey “bark” structure that is wrinkled in order to create more surface area for 20+ billion neurons.
Organized into 4 lobes in each of two hemispheres.
30
The Lobes of the Cerebral Cortex: Preview
Frontal Lobes
Parietal Lobes
Occipital Lobes
______________
involved in speaking and muscle movements and in making plans and judgments
include the sensory cortex
include the visual areas; they receive visual information from the opposite visual field
include the auditory processing areas
Input: Sensory cortex (Left hemisphere section receives input from the body’s right side)
Output: Motor cortex (Left hemisphere section controls the body’s right side)
Functions of the Brain: The Motor and Sensory Strips
Axons receiving motor signals FROM the cortex
Axons sending sensory
information TO the cortex
Sensory Functions of the Cortex
The sensory strip deals with information from touch stimuli.
The occipital lobe deals with visual information.
Auditory information is sent to the temporal lobe.
___________ function of the cortexMore complex animals have more cortical space devoted to integrating/associating information
Our Two Hemispheres
_________________________ (“going to one side”)The two hemispheres serve some different functions. How do we know about these differences? Brain damage studies revealed many functions of
the left hemisphere. Brain scans and split brain studies show more about
the functions of the two hemispheres, and how they coordinate with each other.
• Thoughts and logic
• Language: words and definitions
• Pieces and details
• Feelings and intuition
• Language: tone, inflection, context
• Wholes, including the self
The intact but lateralized brainRight-Left Hemisphere Differences
Left Hemisphere Right Hemisphere