EXAM 2: CHAPTER 3 Flashcards
4 biological basis of behaviour
- Neurons
- Central/peripheral system
- The brain
- Epigenetics
Neuron
Single cell within the nervous system. A group of neurons form a nerve. They are filled with cytoplasm containing nucleus residence of chromosomes that contain genetic material, as well as organelles
Afferent neurons
Carries sensory information from the body to the CNS
Efferent neurons
Carries information out from the CNS to the muscles and glands
Interneurons
Neurons that have a short axon and serve as a relay between different classes of neurons. They communicate with both sensory and motor neurons
Glial cells
The other cells that make up the nervous system. It provides support and protection to neurons and maintains homeostasis, as well as cleans debris
4 main functions of glial cells (5)
- Create barrier between CNS and circulatory system to avoid virus and bacteria
- Control nutrient (glucose) supply to neurons
- Destroy and remove diseased and dead neurons
- Provide axons with myelin sheath
- Establish, maintain, rebuild synapses
3 main parts of a neurone
Dendrites, an axon, and a cell body (soma)
Dendrites
Receives information from other neurons
Axon
Transmits information to other neurons, muscles, and glands
Cell body
Nucleus with chromosomes
Myelin sheath
Helps efficient transmission of signals to other cells. Fatty white substance formed from glial cells that insulate the axons of many neurons
Nodes of Ranvier
Gaps in the myelin sheath that allow ions to diffuse in and out of neuron
Gray matter
Where synapses occur, and where interneurons are located
White matter
Myelinated nerve tracts (bundle of axons)
Resting potential
When a neuron is at rest, and not conducting an impulse
Voltage across membrane of axon at resting
-65v
Action potential
When a neuron fires, pores in the neuron (ion channels) open to let charged ions flow in and out of neuron (sodium-potassium pump) and the shift in electrical charge triggers axon terminals to release neurotransmitters
Refractory period
The time following an action potential. K+ ions are returned to inside of axon and Na to the outside back to original
Neurotransmitters
Chemical substances released by a transmitting neuron at the synapse that alters activity of a receiving neuron
Examples of major neurotransmitters
Acetylcholine, dopamine, serotonin, norpinephrine, endorphins
Acetylcholine
Enables muscle action, learning and memory. Important for stimulating muscles and communication between motor and sensory neurons (arousal, attention, memory)
Dopamine
Influences movement, learning, attention and emotion, produced by neurone in hindbrain
Serotonin
Affects mood, hunger, sleep arousal
Norepinephrine
Helps control alertness and arousal
Terminal buttons
Small knobs at the end of the axon that secretes neurotransmitters and plays a role in communication between neurons
Synapse
Junction between the axon tip of the sending neuron and the dendrite or cell body of receiving neuron
Reuptake
When neurotransmitter molecules have been released at a synapse are reabsorbed by the presynaptic neuron that released them
Neural networks
Complex webs of interconnected neurons that form with experience. Series of algorithms that endeavors to recognize underlying relationships in a set of data through process that mimics the way human brain operates
Significance of the nervous system
Without it, we would not have the 5 senses. We would not be able to move our muscles, talk, breathe, and cells would lack oxygen and nutrients required to live
Central nervous system (3)
- Brain and spinal cord
- Spinal cord is the primary means for transmitting messages between brain and body
- It interprets incoming information from the PNS and sends out messages to muscles, glands, and organs
Spinal cord
Portion of central nervous system that extends down from base of brain and mediates sensory and motor information
Spinal nerves
Part of the peripheral nervous system. Consists of 31 pairs made up of sensory/motor fibres attached to spinal cord and pertain to a specific body area
Significance of interneurons in spine
Triggers reflexes
Peripheral nervous system
Rest of the nervous system made up of long axons and dendrites. It handles input and output from the CNS about what is going on inside and outside of body
2 divisions of the PNS
- Somatic division: Voluntary nerves that go to skin and muscles
- Autonomic division: Involuntary nerves that connect the CNS to organs such as heart, stomach, and intestines
2 components of the autonomic nervous system
- Sympathetic nervous system: Significant for emergency situations because it triggers your fight or flight
- Parasympathetic nervous system: Promotes all internal responses associated with a relaxed state
Weight of a brain
3lbs
4 lobes of cerebrum:
- Frontal
- Parietal
- Temporal
- Occipital
Occipital lobe
Lobe of the cortex at back of skull important for visual information (Color, patterns, etc)
Parietal lobe
Lobe of cortex involved in processing information related to touch and complex visual information, particularly about locations and contains somatosensory strip
Temporal lobe
Part of cortex important in processing sound in speech, comprehension, and recognizing visual stimuli like face
Frontal lobe
Lobe of cortex located front of brain (behind forehead). Important for temporal planning, understanding social relationships and movement
Prefrontal lobe
Portion of frontal cortex involved in higher-order thinking, like memory, moral reasoning and planning
Left hemisphere of brain significance
Referred to as the logical side
Right hemisphere of the brain significance
Referred to as the intuitive side
Corpus callosum
Transmits impulses between the two cerebral hemispheres (right and left sides of the brain)
Motor cortex
Located at the back of frontal lobe next to the parietal lobe and generates signals to direct the movement of the body
Sensory cortex
Located at the end of the parietal lobe responsible for receiving and processing sensory information from across the body, such as touch and temperature
2 kinds of plasticity
General experiences and idiosyncratic experiences
Brain plasticity and significance
Refers to the capacity of the brain to be affected by experience. Without this ability, any brain would be unable to develop from infancy through to adulthood
Neurogenesis
Process by which new neurons are formed in the brain
Epigenetics
Environmental influences that determine whether genes are expressed, or the degree to which they are expressed, without altering the basic DNA sequences that constitute the genes themselves
Examples of epigenetics
Rat studies, what happens when children see abuse, eating patterns/effects
DNA methylation
- Biological process by which methyl groups are added to the DNA molecule
- Critical regulatory mechanism implicated in development, learning, memory, and disease
Histone modification
Adds chemical modification to proteins (histones) that package DNA. Can switch genes off and on. This modification influences gene expression but not DNA sequence
Research results from DNA methylation 1
Research found that 12 men who had suffered abuse had increased levels of DNA methylation at hippocampal receptor gene
Research results from DNA methylation 2
Men who had been sexually abused went on to hurt children. Whereas the others were less likely to display violent behavior than the average population
Neuroscience
Study of brain and nervous system
Dream of external life beliefs
States that cellular life and death determine aging and time of death
Heaven project
Proposed by Dr. Sergio Canavero who will attempt to transplant a human head to the body of another person
What field of studies have helped advance research on the brain
Computer science, engineering, and physics
Ways to study brain without causing damage to tissue (4):
- Examining autopsy tissue
- Testing behavior of patients with assumed damage to certain parts of brain
- Recording electrical brain activity through multiple electrodes attached to surface of scalp
- Animal studies
Significance of examining autopsy tissue
Allows neuroscientists to see what our brains look like but not much about how the systems worked
Significance of testing behavior of patients with assumed damage to certain parts of brain
Studied patients with brain damage. Allows researchers to make assumptions based on information about how brain normally functions from behavioural changes
Significance of recording electrical brain activity through multiple electrodes attached to surface of scalp
Study using electroencephalograms (EEGS) to measure activity of brain during certain states (awake, asleep)
Significance of animal studies
Studies of animal nervous system that allows researchers to look at structure, function, and activity of specific areas of brain
EEG
Non-invasive technique used to detect and localize electrical activity in brain
The brain at work
3D computer generated image of a human brain that shows areas of brain activation in individual undergoing moral decision making
Neuroimaging
Technique that allows for studying brain activity and structure by obtaining visual images in awake humans
Computed tomographic scan (CT)
Clear, detailed, two-dimensional X-ray images of brain/other organs using radiation
Magnetic resonance imaging (MRI)
Magnetic field that produces very clear three-dimensional images of brain. Does not use radiation
Comparison of CT’s and MRI’s
- CT’s are better at detecting problems (Eg. Stroke, blood vessel abnormalities, cancer)
- MRI’s are better at detecting soft tissue injuries in tendons and ligaments and injuries to spinal cord or brain
Diffusion tensor imaging (DTI)
Newest structural imaging technique. Measures orientation and integrity of white matter to assess damage in brain
Transcranial magnetic stimulation (TMS)
Delivers electromagnetic pulse to targeted brain area which temporarily disrupts brain activity in conscious person
Positron emission tomography (PET)
Procedure to see activity of brain during cognitive task using radioactive glucose
Dr Wilder Penfield
Considered the greatest living Canadian for ground breaking work in understanding how the brain works. He began developing neurosurgical techniques to treat epilepsy
Montreal procedure
- Procedure developed by Penfield and colleagues to operate on brains of epileptic patients and destroy cells where seizures originated
- Can find neural activity that causes seizure by electrically stimulating brain in temporal lov
Seizures
A burst of uncontrolled electrical activity between brain cells. Prior to a seizure, many people will experience a particular sensory experience like smell
quadriplegic
When individual breaks neck and permanently damages spinal cord close to brain, they will lose touch and pain sensation everywhere but their heads and faces
parapalegic
When individual encounters damage farther down the back, then they may retain sensation and usage of upper libs but not the lower limbs
How many Canadians live with spinal injury and how many new cases a year
86,000 living and 1500 each year
Rick Hansen institute
Encourages and supports spinal cord research
Hindbrain
Part of brain closest to spinal cord consisting of the medulla, the pons, and the cerebellum
Major parts of the brain (13):
- Corpus Callosum
- Cerebral cortex
- Hypothalamus
- Pituitary gland
- Amygdala
- Hippocampus
- Hindbrain
- Reticular formation
- Medulla
- Cerebellum
- Pons
- Substantia nigra
- Thalamus
Medulla
Part of brain that controls basic bodily processes and regulates certain reflexes (Eg. Heart rate, respiration, sneezing, coughing)
The Pons
Uppermost or front part of brainstem and regulates sleep, dreaming, breathing, swallowing, eye movements, facial sensation
Norepinephrine
A neurotransmitter used for arousal and attention
Cerebellum
Portion of the brain located near the back of head important for motor coordination and learning
Reticular formation
Complex neutral network extending from hindbrain into midbrain that plays a central role in regulating consciousness and arousal
Midbrain
Topmost part of brain stem (connection of spinal cord and brain). Contains different nuclei and has a crucial role in processing visual and auditory signals
Substantia nigra
Brain region important for fluidity of movement and inhibiting movements
Forebrain
LARGEST subdivision of brain which controls cognitive, emotional, sensory and motor functions. It is divided into two cerebral hemispheres connected by band of white matter called corpus callosum
What is the outer layer of each hemisphere of brain called
Outer layer of each hemisphere is composed of grey matter cerebral cortex
Thalamus
Area of brain that serves as a relay station for incoming sensory information
Hypothalamus
Brain structure important for motivation and control of the endocrine system (Eg. Eating, drinking, sex, sleep)
Endocrine system
System that controls levels of hormones throughout body
Pituitary gland
Located under hypothalamus. Brain structure that plays role in controlling the endocrine system by releasing hormones to ovaries, testes, thyroid, adrenal glands
Limbic system
Group of interconnected brain structures (hippocampus, amygdala, hypothalamus, thalamus) associated with learning, memory, basic emotions and drives
Amygdala
Brain area involved in processing information about emotions (usually fear)
Hippocampus
Brain region important for learning and memory
Basal ganglia
Group of subcortical nuclei responsible primarily for motor control. As well as other roles such as motor learning, executive functions, behaviors and emotions
Nucleus accumbens
Brain area important for motivation and reward
Cerebral cortex
Largest portion of brain responsible for complex behaviors like language and thought
Function of primary sensory/motor areas
Responsible for processing basic sensory information as well as directions for voluntary movement
Association cortex
Responsible for many complex functions including higher-order sensory processing, thinking, and planning
Wernicke’s area
Area of temporal cortex important in helping us understand language
Broca’s area
Area of frontal lobe critical for speaking
Somatosensory strip
Band of cortex that processes tactile (touch, pressure, vibration, pain)
Damage in prefrontal cortex results in..
Difficulty understanding ethical principles despite having normal IQ
Unique form of therapy to improve those who have been affected by brain injury
Music therapy
Kevin Englehart
Working with a team to develop a neural machine interface to control upper limb prostheses so that amputees can regain mobility and motor function
Axon termina
End of a neuron’s axon from which neurotransmitters are released
Sensory neuron
Respond to pressure, temperature, pain
Motor neurons
Respond to changes in muscle length or tension and stimulate many muscle cells into action
Types of glia cells:
- Astroglia
- Obliodendroglia
- Ependymal cells
- Microglia
Astroglia
Creating blood-brain barrier; system regulating passage of molecules from blood to brain
Obliodendroglia
Providing a protective fatty sheath (coating) called myelin sheath that insulates axons of neurons
Ependymal cells
Specialized cells that line the walls of ventricles, fluid filled spaces within brain. They create and secrete cerebrospinal fluid (CSF)
Microglia
Cleaning up debris of degenerating or dead neurons
How many neurons in body
100 billion
Steps on how neurons communicate (5):
- Electrical signal is generated at the cell body of the presynaptic neuron
- This electrical signal, called an action potential, travels down the axon to the axon terminals
- Chemicals called neurotransmitters, such as dopamine, are released from the axon terminals.
- These chemicals float across the synaptic space between neurons and bind to neurotransmitter receptors, usually found on the dendrites, on the next neuron
- When these neurotransmitters bind to the next neuron, they may change the electrical activity of that neuron, which can start this whole process going again
Key elements that keep the inside environment of a neuron and its axon negative (4):
- Relative imbalance of positively and negatively charged ions inside versus outside neuron
- Semi-permeable nature of cell membrane
- Electrostatic pressure and concentration gradients
- Sodium-Potassium pump
3 main ions important for resting and action potential
Negatively charged proteins, positively charged sodium and potassium
Ion channels
Pores in cell membrane that can open and close to arrow certain ions into and out of cell
Electrostatic pressure
Force that drives ions that are of similar charge away from one another or attracts two ions of opposite charges towards each other
Concentration gradient
The difference in concentration of sodium ions inside and outside of neuron
Sodium potassium pump
Protein molecules in the membrane of cells that push out sodium ions and push in potassium ions
Action potential
Spike or neuron impulse that occurs when enough sodium enters cell to push relative electrical difference across membrane
Threshold
The point at which the relative influence of other neurons succeeds in causing a neuron to initiate an action potential
Absolute refractory period
Very brief period of time after an action potential, during which a neuron is completely unable to fire again
Relative refractory period
A brief period just after absolute refractory period during which a neuron can fire only if it receives a stimulus stronger than its usual threshold
Synapses
Tiny spaces between axon terminal of one neuron and the neuron through which chemical communication occurs
Synaptic vesicles
Membrane-bound spheres in the axon terminals of neurons in which neurotransmitters are stored before their release
Neurotransmitter receptors
Proteins in the membranes of neurons that bind to neurotransmitters
Postsynaptic potentials
Electrical events in postsynaptic neurons that occur when a neurotransmitter binds to one of its receptors
Depolarization
What occurs when the inside of neuron membrane becomes less negative relative to outside
Hyperpolarization
What occurs when inside of neuron membrane becomes more negative relative to outside
Enzymatic degradation
Breaking down neurotransmitter that remains in synaptic cleft by specialized enzymes or proteins
Reuptake
Functional neurotransmitter molecules are drawn back into the presynaptic neuron and recycled for future use
GABA
Most common inhibitory neurotransmitter that reduces activity of neuron it binds to
Glutamate
Most important transmitter of normal brain function. It is needed to keep brain function steady. Also plays a role in shaping learning and memory
Neuroplasticity
The brain’s ability to create new neutral pathways as a result of experience or following an injury
Hemispheres
Two sides of the brain
Common myth of our brains
We only use 10% of our brain
