4 THE BRAIN Flashcards
What is the human brain primarily composed of?
75 to 80 percent water, with the rest mostly fat and protein.
How has the consistency of the brain been described?
Like tofu, soft butter, or slightly overcooked Jell-O pudding.
True or False: The brain has pain receptors.
False.
What does the brain use to create our perception of the world?
A stream of electrical pulses.
How much information can a cubic millimeter of cortex hold?
Two thousand terabytes.
What percentage of body weight does the brain constitute?
2 percent.
What percentage of the body’s energy does the brain use?
20 percent.
What is the main function of the frontal lobe?
Reasoning, forethought, problem solving, emotional control.
Fill in the blank: The two hemispheres of the cerebrum are connected by the _______.
corpus callosum.
What are the four lobes of the cerebrum?
- Frontal
- Parietal
- Occipital
- Temporal
What is the primary function of the occipital lobe?
Processing visual information.
What is the cerebellum responsible for?
Balance and complex movements.
What is the oldest part of the brain?
The brain stem.
What role does the hypothalamus play in the brain?
Regulates sexual function, hunger, thirst, blood sugar, and sleep.
What is the function of the hippocampus?
Laying down of memories.
True or False: The amygdala is involved in processing intense emotions.
True.
What is the concept of the limbic system associated with?
Controlling and regulating basic processes like memory and emotions.
What did Paul D. MacLean contribute to neuroscience?
Invented the concept of the limbic system.
What is the estimated number of neurons in the human brain?
About 86 billion.
Fill in the blank: Neurons pass on electrical signals through their long strands called _______.
axons.
What is the tiny space between nerve cell endings called?
Synapse.
How does the brain process visual information?
Only about 10 percent comes from the optic nerve; the rest is interpreted by other brain areas.
What is a significant challenge in understanding the brain?
Understanding consciousness and the nature of thoughts.
What happens when the amygdala is damaged?
The individual may become fearless and unable to recognize fear in others.
What is the relationship between the brain and energy consumption?
The brain burns energy at a steady rate, regardless of activity.
How does the brain forecast future events?
It continuously predicts what the world will be like a fifth of a second ahead.
How long does it take for information to travel along the optic nerves to the brain?
About two hundred milliseconds, or one-fifth of a second.
What extraordinary ability does the brain possess to deal with the lag in sensory processing?
It continuously forecasts what the world will be like a fifth of a second from now.
True or False: We see the world as it is at this very instant.
False.
What phenomenon do we experience when we hear a plane and see it at different times?
The difference in the speeds of sound and light.
What is the nature of photons of light, sound waves, and olfactory molecules?
They have no inherent color, sound, or smell.
Fill in the blank: Color is not a fixed reality but a _______.
perception.
What is an afterimage?
A ghostly color perceived after staring at a colored object and shifting focus.
What does the brain excel at finding in chaotic stimuli?
Patterns and determining order.
Who created the Kanizsa triangle illusion?
Gaetano Kanizsa.
What is anterograde amnesia?
The inability to form new memories.
What did Elizabeth Loftus discover about false memories?
It is possible to implant entirely false memories through suggestion.
What did psychologists find about people’s memories of 9/11 one year later?
Nearly half contradicted themselves in significant ways.
What is the primary role of the hippocampus in memory?
Laying down memories.
What are the two principal varieties of memory?
Declarative and procedural.
What type of memory includes facts that can be verbally expressed?
Declarative memory.
What is procedural memory?
Knowledge that is understood but difficult to articulate.
What is the duration of short-term memory?
No more than half a minute.
True or False: Most people’s short-term memory can reliably retain six random words or digits.
True.
What did Wilder Penfield’s experiments suggest about memory storage?
Every conscious event is stored permanently in the brain.
What is the nature of memory storage according to modern understanding?
Hazy and mutable, not a fixed record.
Who was Henry Molaison?
A man who lost the ability to form new memories after brain surgery.
What is the cerebral cortex?
The outer layer of the brain where higher processes occur.
Who mapped the regions of the cerebral cortex?
Korbinian Brodmann.
What are Brodmann areas?
Forty-seven distinct regions of the cerebral cortex identified by Brodmann.
What is the primary composition of white matter in the brain?
Myelinated neurons.
Fill in the blank: The idea that we use only 10 percent of our brains is a _______.
myth.
What is the color of gray matter in life?
Pinkish blush
Gray matter appears gray in the absence of blood flow and with preservatives.
What posthumous attribute does white matter have?
Luminous white due to the pickling process
The myelin coatings on nerve fibers turn white when preserved.
Is the idea that we use only 10 percent of our brains true?
No, it is a myth
All parts of the brain are used, even if not all are used sensibly.
What percentage of completion is a teenager’s brain by the age of 18?
About 80 percent
The brain is mostly developed by age ten but not fully wired until mid- to late twenties.
What region of the forebrain is associated with pleasure and grows during teenage years?
Nucleus accumbens
This area is linked to increased dopamine production during adolescence.
What is the leading cause of deaths among teenagers?
Accidents
The risk of accidents increases significantly when multiple teenagers are present.
What are glial cells, and how do they compare to neurons in number?
Supportive cells that outnumber neurons by ten to one
Glia play important roles beyond physical support, including producing myelin.
What is the current understanding regarding the brain’s ability to produce new neurons?
Disagreement exists; some studies suggest limited neurogenesis in the hippocampi
New neurons are insufficient to offset loss from aging or conditions like stroke.
What significant case in neuroscience demonstrated that brain damage could change personality?
Phineas Gage
Gage survived a severe brain injury but experienced drastic personality changes.
Who is known for performing lobotomies, and what was his method?
Walter Jackson Freeman; he used an ice pick through the eye socket
Freeman’s methods were often criticized for being crude and lacking surgical standards.
What was the outcome for Rosemary Kennedy after her lobotomy?
She lost her personality and spent decades in a care home
Her lobotomy left her unable to speak and largely unresponsive.
What are contrecoup injuries?
Injuries that appear on the opposite side of the brain from the point of impact
These injuries occur when the brain is violently thrust against the skull.
What is the second most common cause of death globally according to the WHO?
Strokes
Despite good blood supply to the brain, strokes remain prevalent in humans.
What is epilepsy characterized by?
Misfiring neurons in the brain
Symptoms range from brief lapses of awareness to prolonged convulsions.
What percentage of epileptics do not respond to medications?
About 20 percent
Some epileptics experience sudden unexpected death during or after seizures.
What is Anton-Babinski syndrome?
A condition associated with neural disorders
It reflects the diverse and often bizarre syndromes linked to brain dysfunction.
What is the Anton-Babinski syndrome?
A condition in which people are blind but refuse to believe it
This syndrome highlights the complexities of perception and belief in neurological conditions.
What happens in Riddoch syndrome?
Victims cannot see objects unless they are in motion
This condition demonstrates the brain’s processing of visual stimuli.
What is Capgras syndrome?
A condition in which sufferers become convinced that those close to them are impostors
This syndrome raises questions about identity and recognition in the brain.
Describe Klüver-Bucy syndrome.
Victims develop an urge to eat and fornicate indiscriminately
This condition can cause significant distress to loved ones due to altered behaviors.
What is Cotard delusion?
A condition in which the sufferer believes he is dead and cannot be convinced otherwise
This delusion reflects extreme cognitive dissonance regarding self-perception.
What are the different states of consciousness mentioned?
Coma, vegetative state, minimally conscious state, locked-in syndrome
Each state reflects varying levels of awareness and responsiveness.
What did Adrian Owen discover about patients in a vegetative state?
Some are fully aware but powerless to indicate it
This discovery challenges previous assumptions about consciousness in brain-injured patients.
What method did researchers use to determine Amy’s consciousness?
fMRI scanner to observe neural responses
This technique allows for non-invasive insight into brain activity.
What percentage of people thought to be in a permanent vegetative state are actually aware, according to Owen?
15 to 20 percent
This statistic highlights the challenges in diagnosing consciousness.
How has the average human brain size changed over the last 10-12 thousand years?
It has shrunk from 1,500 cubic centimeters to 1,350 cubic centimeters
This change raises questions about human evolution and cognitive efficiency.
What is the presumed reason for the brain size reduction?
Brains have become more efficient and able to pack more performance into a smaller space
This analogy compares brain evolution to advancements in technology.
What has happened to human skull thickness over time?
Skulls have also become thinner
This change may reflect lifestyle shifts and reduced physical demands.
True or False: The average human brain has increased in size over the last 10,000 years.
False
The brain has actually decreased in size during this period.
Fill in the blank: The _______ is a condition where individuals cannot see objects unless they are in motion.
Riddoch syndrome
This syndrome illustrates unique visual processing challenges.
What is a significant challenge in diagnosing consciousness in patients?
It is difficult to determine if a brain is working without the owner’s indication
This highlights the limitations of current medical assessments of consciousness.
List the states of consciousness in increasing order of awareness.
- Coma
- Vegetative state
- Minimally conscious state
- Locked-in syndrome
Each state represents a different level of cognitive function and interaction.
