Chapter 1 Flashcards
What is the function of the brain?
Nerve center; processes info
How many neurons does the brain contain?
Billions
Can the brain perform multiple tasks at once?
Yes
What is the largest part of the human brain?
Cerebrum
What connects the two hemispheres of the brain?
Corpus callosum
How many hemispheres is the cerebrum divided into?
Two
What is the surface layer of the cerebrum called?
Cerebral cortex
What do the folds of the cerebral cortex do?
Increase area for neurons
How do neuroscientists identify regions of each hemisphere?
Separate lobes
Where are the frontal lobes located?
Front of the brain, above eyes
What functions do the frontal lobes coordinate?
Movement, speech, memory
Where are the parietal lobes located?
Top of the brain, behind frontal lobes
What do the occipital lobes process?
Visual information
What are the occipital lobes responsible for recognizing?
Colors and shapes
Where are the temporal lobes located?
Sides of the brain
What type of information do temporal lobes interpret?
Auditory information
What is the function of the hippocampus?
Encodes new memories
What does the amygdala integrate?
Memory and emotion
What system do the hippocampus and amygdala belong to?
Limbic system
What role does the thalamus play?
Integrates sensory information
What does the hypothalamus send to the body?
Hormonal signals
What structures make up the forebrain?
Cerebral cortex and others
Where does the midbrain sit?
Beneath the thalamus
What functions do neurons in the midbrain coordinate?
Eye movements
What is an example of a reflex triggered by the midbrain?
Startled jump
What does the midbrain help manage?
Fine motor control
What collection of structures helps regulate complex body movements?
Basal ganglia
What part of the brain is involved in glucose regulation and sleep?
Hindbrain
Which part of the brain is the second-largest by volume?
Cerebellum
Where is the cerebellum located?
Under occipital lobe
What contains over half the brain’s neurons?
Cerebellum
What are the functions of the cerebellum?
Coordinates movements, motor skills
What might indicate cerebellar damage?
Jerky gait, poor finger touch
What part of the brain below the cerebellum influences breathing and posture?
Pons
What does the medulla control?
Basic functions
What makes up the brainstem?
Midbrain, pons, medulla
What is the frontal lobe responsible for?
Attention, planning, decision-making
What is the function of the temporal lobe?
Language, memory, emotion
What does the parietal lobe integrate?
Information from senses
What is the responsibility of the occipital lobe?
Vision
What did the brain begin as?
Simple tube
What regions are present in early vertebrates’ brains?
Forebrain, midbrain, hindbrain
What expanded in the forebrain?
Olfactory bulbs
What evolved with the development of eyes?
Light-sensing regions
What part of the brain controls escape movements in fish?
Cerebellum
What functions are expanded in vertebrates for processing?
Visual, auditory
What behaviors do the expanded regions trigger?
Escape, feeding, mating
What formed the cerebral hemispheres?
New types of neurons
What expanded in early mammals?
Cortical tissues
How does information move in the brain?
Chains of neurons
How do neural networks route signals?
Along a linear pathway
What cells in the retina trigger electrical signals?
Photoreceptors
Where do signals travel after the optic nerve?
Optic tract to thalamus
What does the primary visual cortex process?
Shape, color, movement
Where is the primary visual cortex located?
Occipital lobe
What do neurons in the primary visual cortex detect?
Edges of objects
What representation is created by the integration of signals from each eye?
Three-dimensional
What happens to the image as signals are sent down processing streams?
Further refined
What do neurons in the temporal lobe recognize and identify?
Objects
What do neurons in the parietal lobe detect?
Spatial location of objects
What do new technologies allow us to see?
Brain regions activated during different functions
What creates brain waves?
Network activity
What is an example of a thalamocortical loop?
Visual cortex sending signals back to the thalamus to integrate with other sensory information
What produces rhythmic electrical patterns detected by EEG?
Neuronal signals
What are the rhythmic electrical patterns called?
Brain waves
How many distinct types of brain waves are there?
Four
What are alpha waves?
8-13 Hz, relaxed brain
Where do alpha waves originate?
Parietal and occipital lobes
What are beta waves?
14-30 Hz, active brain
Where do beta waves originate?
Frontal and parietal regions
What frequency range do theta waves have?
4 to 7 Hz
What frequency is typical for delta waves?
< 3.5 Hz
Which waves occur during deep sleep?
Delta waves
What is the amplitude range for alpha waves?
20–200 μV
What is the amplitude range for delta waves?
20–200 μV
What is the amplitude range for theta waves?
5-10 μV
What is the amplitude range for beta waves?
5-10 μV
What are neural networks?
Organized and integrated information passages in the brain and spinal cord.
What are spinal tracts?
Chains of neurons passing signals through the brainstem and spinal cord.
What is the purpose of spinal tracts?
To pass signals from sensory receptors to the thalamus and cortex, and from brain regions to muscles.
What do basal ganglia do?
Feedback loop for movement
What influences the timing and strength of motor signals?
Loops from brainstem and cerebellum
What enables environmental and emotional context to influence body movements?
Tracts from cerebral cortex
What do networks looping the hippocampus into sensory cortex pathways do?
Analyze environmental signals
What do networks linking the hippocampus to the thalamus and hypothalamus influence?
Memory impacts behavior
What are reflex loops?
Action before thoughts
Where are reflex actions controlled?
Spinal cord or subcortical regions
What do brain regions analyze?
Specialized subsets of information
What do local neural circuits do?
Turn signals into output patterns
What is a characteristic of the cerebral cortex?
Packed with neural circuits
How are neurons organized within the cerebral cortex?
Stack of distinct layers
How are circuits arranged within the cerebral cortex?
Columns
How are signals processed within a column of neurons?
Travel down a chain from one neuron to the next
What does each column in the cortex do?
Specific processing task
How can a column’s output be influenced?
Nearby circuits activity
What behavior do neurons exhibit?
Like microprocessors
What affects a neuron’s response?
Strength of signals
How are neurons organized in the cortex?
Into distinct layers
What percentage of neurons are excitatory?
About 80 percent
What is the most common type of excitatory neuron?
Pyramidal cell
What shape is the cell body of a pyramidal cell?
Cone-shaped
What type of axon sends a signal to multiple destinations?
Multi-branched axon
What percentage of neurons in the brain are inhibitory?
20 percent
What do inhibitory neurons do?
Suppress neighboring neurons
What type of neurons pass signals forward in a circuit?
Excitatory neurons
Where do inhibitory neurons typically loop their responses?
Earlier segments
What is important in learning and tuning signals in the brain?
Interplay of signals
What could cause seizure disorders like epilepsy?
Imbalances in neuron activity
What is a feed-forward inhibitory circuit?
Inhibitory interneurons connect circuits.
What does a feed-forward inhibitory circuit do?
Reduces activity in adjacent columns.
What characterizes feedback inhibition?
Signals inhibit preceding layers.
What is the functional unit of neural circuits?
Neuron
What are the main parts of a neuron?
Cell body, dendrites, axon
What is the cell body also called?
Soma
What does the cell body contain?
Nucleus, cytoplasm
What are dendrites responsible for?
Collecting incoming signals
What do electrical signals travel down?
Axon
What are axon terminals?
End points of axon
What is passed across a synapse?
Signal
What types of cells are neurons associated with?
Glia
How many main types of glial cells are in the CNS?
Four
What are the types of glial cells in the CNS?
Astrocytes, microglia, ependymal cells, oligodendrocytes
What was the believed ratio of glia to neurons before recent investigations?
0.41736111111111107
What is the suggested glia-neuron ratio in some brain regions?
0.04236111111111107
Do glia-neuron ratios vary across brain regions?
Yes
¿Qué regulan los astrocitos?
Concentraciones de iones
¿Qué nutrientes proporcionan los astrocitos?
Nutrientes a las neuronas
¿Qué papel juegan las microglías?
Células inmunitarias
¿Cómo protegen las microglías el cerebro?
Fagocitos
¿Qué regulan las microglías?
Conexiones neuronales
What do ependymal cells do?
Make cerebrospinal fluid
How do oligodendrocytes improve neuron function?
Wrap axons in myelin
What allows ions to cross a neuron’s cell membrane?
Ion channels
What do ion channels do?
Act like gates for ions
What changes when ions enter or leave the cell?
Voltage difference
What is the resting membrane potential of a neuron?
-70 mV
What are the two types of signals that affect membrane potential?
Depolarized and hyperpolarized
What triggers an action potential?
Threshold voltage
What are signals passed through?
Synapses
What does a synapse include?
Axon end, dendrite, synaptic cleft
When was the separation between neurons verified?
1950s
What crosses the synapse?
Neurotransmitters
What triggers ion channels to open?
Voltage change
What ions flow into the cell?
Calcium ions
What happens when calcium ions bind to synaptic vesicles?
Vesicles fuse with cell membrane
What do synaptic vesicles release into the synaptic cleft?
Neurotransmitter molecules
What is cycled back into the soma?
Pieces of axon terminal membrane
What substances can act as neurotransmitters?
Amino acids, gases, chemicals, peptides
What is the basic building block of the nervous system?
Neuron
What do dendrites do?
Receive signals
What is released by axon terminals?
Neurotransmitters
What is the function of the axon?
Send signals
What structures are contained in the cell body?
Nucleus
What are the sites called where dendrites receive information?
Synapses
What forms complex circuits in the brain?
Synapses on dendrites
What colors label synapses in the mouse neuron?
Yellow and red
What is the postsynaptic density?
Dense receptor area
How do neurotransmitters interact with receptors?
Key fits a lock
What happens to neurotransmitters after release?
Drift across synaptic cleft
What is located in high concentration at the postsynaptic density?
Neurotransmitter receptors
What happens when neurotransmitters bind to receptors?
Open ion channels
What do astrocytes do at the synapse?
Mop up excess neurotransmitters
What is an ionotropic receptor?
Binds neurotransmitter directly to ion channel
What happens when a neurotransmitter attaches to the ion channel?
Channel widens, ions move
How are metabotropic receptors different from ion channels?
Different proteins, distant
What triggers the cascade in metabotropic receptors?
Neurotransmitter binding
What is the brain’s most common excitatory neurotransmitter?
Glutamate
What is the brain’s most common inhibitory neurotransmitter?
GABA
What do excitatory neurons produce?
Depolarizing neurotransmitters
What do inhibitory neurons produce?
Hyperpolarizing neurotransmitters
What is a key characteristic of glutamate?
Half the excitatory synapses
What are the most important ionotropic receptors?
AMPA and NMDA receptors
What is the action of AMPA receptors?
Fast and brief
How do NMDA receptors activate?
More slowly
What is the role of interactions between AMPA and NMDA receptors?
Learning and memory
What is the most important inhibitory neurotransmitter?
GABA
What groups of receptors does GABA bind to?
Ionotropic and metabotropic
What do ionotropic GABA receptors let enter the cell?
Negatively charged chloride ions
What do metabotropic GABA receptors release?
Potassium ions
What is the effect of ion movement in GABA receptors?
Inhibits neuron firing
What role do hormones play in the brain?
Send specific cues
What are endocannabinoids?
Neuromodulators that suppress neurotransmitter release
What do prostaglandins increase?
Pain sensitivity
What triggers a series of chemical reactions inside the cell?
Hormones and neuromodulators
What initiates the signal transduction pathway?
Molecule binding to receptor
What happens when a molecule binds to a surface receptor?
Changes receptor shape
What does the signal transduction pathway modify?
Neuronal function
How can steroid hormones like estradiol act inside a neuron?
Diffuse through cell membrane
What determines whether a neuron’s signal is excitatory or inhibitory?
Type of neurotransmitter
What determines a cell’s sensitivity to specific neurotransmitters?
Neurotransmitter receptors
What can influence neuronal behavior?
Neuromodulators
What are examples of neuromodulators that influence neuronal behavior?
Hormones (vasopressin, estradiol, cortisol)
Where are neuromodulator receptors located?
Cell membranes
What is gene expression?
Directs cellular activities
What do differences among neurons result from?
Differences in gene expression
How do cells build proteins?
From a subset of genes
What is an analogy for gene expression differences?
Building with Lego blocks
What do genes need to be accessible?
Open, unfolded chromatin
What associates with unexpressed genes?
Tightly packed regions
What can shut down genes on DNA?
Tightening chromatin
What activates genes on DNA?
Spreading chromatin
What makes neurons flexible in altering their gene expression?
Reversible changes
Where can genetic differences between individuals be found?
Genes that affect neuron structure and function
What do alleles reflect?
Nucleotide sequence differences
What can alleles produce?
Variants that affect protein function
What does an allele code for?
Version of an enzyme
What condition is caused by Tay-Sachs disease?
Mutations in enzyme gene
What enzyme is affected in Tay-Sachs disease?
Beta-hexosaminidase A
What accumulates in neurons due to Tay-Sachs?
Specific fats
What is the outcome of fat accumulation in Tay-Sachs?
Toxicity
What affects brain function?
Small changes in genetic sequence
What is now possible for understanding brain disorders?
Sequence a person’s entire genome
What acts as neurotransmitters?
Many different molecules
What is the receptor’s role?
Fits neurotransmitters like a key fits a lock
