Neuroscience: Action Potentials and Synapses

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Questions and Answers

What occurs during depolarization of a neuron?

Membrane becomes more negative

Membrane becomes less negative (correct)

Membrane maintains a neutral charge

Membrane becomes hyperpolarized

What is the role of the absolute refractory period?

Allows immediate firing of the neuron

Prevents the neuron from firing again immediately (correct)

Shortens the duration of an action potential

Facilitates weaker stimulation to trigger firing

How does an excitatory synapse influence a postsynaptic neuron?

Increases negative charge inside the neuron

Decreases the likelihood of firing an action potential

Makes the inside of the neuron more positive (correct)

Induces hyperpolarization of the neuron

What effect does GABA have on a postsynaptic neuron?

Decreases the likelihood of firing an action potential Signup and view all the answers

What occurs to the brain during sensitization when repeatedly exposed to a stimulus?

Calcium influx into neurons increases. Signup and view all the answers

What relationship does the all-or-none law describe in neuronal firing?

There is a threshold that must be surpassed to fire Signup and view all the answers

Which neurotransmitter is primarily associated with mood regulation and is linked to depression when undersupplied?

Serotonin Signup and view all the answers

Which of the following accurately describes neural reorganization?

Different brain regions take on new functions. Signup and view all the answers

What is a characteristic of synaptic plasticity?

Synapses can change due to learning or experience Signup and view all the answers

Which brain structure is often involved in spatial memory for taxi drivers?

Hippocampus Signup and view all the answers

What phenomenon describes the brain's capacity to adapt through learning new skills?

Neuroplasticity Signup and view all the answers

Which of the following describes habituation?

A decreased response to repeated stimuli Signup and view all the answers

In blind individuals, what change occurs in the occipital lobe?

It takes on roles such as processing auditory information. Signup and view all the answers

What is consistent about the changes observed in musicians due to extensive practice?

Alterations in the motor cortex. Signup and view all the answers

What is one implication of the brain's ability to generate new neurons in adults?

There is potential for learning and recovery from brain damage. Signup and view all the answers

How do neural pathways facilitate communication in the brain?

By connecting neurons to transmit signals across different brain and body parts. Signup and view all the answers

What does damage to the right parietal lobe result in?

Hemineglect or hemi-inattention in the left field of vision Signup and view all the answers

What is the primary function of the corpus callosum?

To allow communication between the left and right hemispheres Signup and view all the answers

In split-brain patients, what happens when an object is presented in the left visual field?

The patient can only draw or point to the object, but not name it Signup and view all the answers

What does a severed corpus callosum result in for split-brain patients?

Independent processing of visual information in each hemisphere Signup and view all the answers

Which of the following are tasks primarily handled by the left hemisphere?

Language and analytical thinking Signup and view all the answers

What can be concluded from Gazzaniga's Split-Brain experiments?

Different tasks are specialized within each hemisphere of the brain Signup and view all the answers

What occurs when the hemispheres cannot communicate effectively in split-brain patients?

They struggle with tasks that require integration of speech and spatial recognition Signup and view all the answers

Which statement about the right hemisphere is correct?

It is responsible for spatial and non-verbal tasks Signup and view all the answers

What is personal unity in the context of consciousness?

The continuous flow of one's thoughts and feelings Signup and view all the answers

What distinguishes exogenous attention from endogenous attention?

Exogenous attention is automatic and stimulus-driven, while endogenous attention is voluntary and goal-driven. Signup and view all the answers

What is the primary focus of the dichotic listening task?

Focusing on one audio stream while ignoring another Signup and view all the answers

What phenomenon is illustrated by the Stroop Effect?

The automatic processing interfering with sensory identification Signup and view all the answers

Change blindness is best described as:

Failing to notice significant environmental changes when attention is diverted Signup and view all the answers

In terms of attention, what does divided attention refer to?

Trying to focus on multiple tasks at once, leading to decreased performance Signup and view all the answers

What is a defining characteristic of inattentional blindness?

Failing to notice obvious stimuli while focused on another task Signup and view all the answers

Which statement accurately describes the relationship between attention and consciousness?

Attention serves as a gateway, essential for full awareness of experiences. Signup and view all the answers

What is Hemineglect primarily associated with?

Ignoring one side of the visual field Signup and view all the answers

Which brain wave is associated with light sleep and relaxation?

Theta Waves Signup and view all the answers

What stage of sleep is characterized by the presence of sleep spindles and K-complexes?

Stage 2 Signup and view all the answers

During which sleep stage does the majority of dreaming occur?

REM Sleep Signup and view all the answers

Which of the following statements about sleep cycles is accurate?

Deep sleep happens earlier in the night. Signup and view all the answers

How does the amount of REM sleep change from infancy to elderly age?

It decreases with age. Signup and view all the answers

What effect do psychoactive drugs have on consciousness?

They alter sensory perception and mood. Signup and view all the answers

What is a K-complex and in what stage of sleep does it occur?

A large wave that helps protect the sleeper in stage 2 sleep Signup and view all the answers

Study Notes

Depolarization, Repolarization, and Hyperpolarization

Depolarization: The membrane potential becomes less negative, moving closer to zero.
Repolarization: The membrane potential returns to its negative resting state after an action potential.
Hyperpolarization: The membrane potential becomes even more negative than the resting potential, making it less likely for an action potential to occur.

Refractory Periods

Absolute Refractory Period: The neuron cannot fire again, regardless of the strength of the stimulus.
Relative Refractory Period: The neuron can fire, but only with a stronger than usual stimulus.

All-or-None Law

Neurons follow an all-or-none principle: They either fire an action potential or they don't.
Stronger stimuli increase the frequency (how often) an action potential is fired, not the strength of the action potential.

Synaptic Transmission

A synapse is the junction between the axon terminal of one neuron and the dendrite or cell body of another neuron.
Excitatory Synapses: Increase the likelihood of the postsynaptic neuron firing an action potential.
- Neurotransmitters like glutamate cause the postsynaptic neuron to become more positive.
- This is called an Excitatory Postsynaptic Potential (EPSP).
Inhibitory Synapses: Decrease the likelihood of the postsynaptic neuron firing an action potential.
- Neurotransmitters like GABA make the postsynaptic neuron more negative.
- This is called an Inhibitory Postsynaptic Potential (IPSP).

Plasticity

Synapses can change their strength and effectiveness due to learning or experience.

Some Neurotransmitters

Dopamine: Plays a role in movement, learning, attention, and emotion.
Serotonin: Influences mood, hunger, sleep, and arousal. Low levels are linked to depression.

Dopamine Hypothesis of Schizophrenia

Excessive dopamine activity is thought to contribute to schizophrenia.

Agonists and Antagonists

Agonists: Drugs that mimic the effects of neurotransmitters.
- Amphetamines are examples of agonists.
Antagonists: Drugs that block the effects of neurotransmitters.
- Chlorpromazine is an example of an antagonist.

Learning and Synapse Plasticity

Habituation: A decrease in response to a repeated stimulus.
Sensitization: An increase in response to a repeated stimulus.

Brain Plasticity:

Neural Reorganization: The brain can adapt and reorganize its neural pathways in response to experience or damage.
- Example: The occipital lobe (vision) may take on new roles in blind individuals.
New Neuron Generation: The adult brain can continue to generate new neurons.

Brain Structure Change with Experience

Changes in brain structure can occur with experience.
- Example: Taxi drivers have larger hippocampi (spatial memory).
Damage to the brain can lead to neural reorganization.

Notable Examples of Brain Plasticity

Taxi drivers: Enlargement of the hippocampus.
Musicians: Changes in the motor cortex due to years of practice.
Bilinguals: Enlarged parietal cortex due to language processing.

Split-Brain Experiments

The corpus callosum is a bundle of nerve fibers that connects the left and right hemispheres of the brain.
Split-brain procedure: The corpus callosum is severed to treat epilepsy, preventing seizures from spreading between hemispheres.
Split-brain patients: Show how the brain hemispheres process information independently.
- The left hemisphere controls language and speech.
- The right hemisphere is involved in spatial and non-verbal tasks.

Damage to the Right Parietal Lobe

Leads to hemineglect or hemi-inattention, where individuals ignore the left side of their visual field.

Key Findings from Split-brain Studies

Each hemisphere processes visual information from the opposite visual field.
Split-brain patients can draw or point to objects presented to the right hemisphere (left visual field), but can't name them.
The left hemisphere is responsible for verbal processing, while the right hemisphere excels in nonverbal tasks.

Consciousness

Consciousness: One's subjective experience of the world.
Sensory awareness: Awareness of the environment.
Direct inner awareness: Awareness of one's own thoughts and feelings.
Personal Unity: The feeling of being a unified self.
Waking state: The state of being awake and aware.

Attention: Gateway to Consciousness

Attention is crucial for consciousness.
Change Blindness: Failure to notice large changes in the environment when attention is elsewhere.
Inattentional Blindness: Failure to notice an obvious object in the visual field when attention is focused on something else.

Types of Attention

Exogenous Attention: Automatic, stimulus-driven attention.
Endogenous Attention: Voluntary, goal-driven attention.

Dichotic Listening and Change Deafness

Dichotic Listening Task: Participants focus on one auditory message while ignoring another.
Change Deafness: Even with focused attention, we may not notice semantic changes in an auditory stream.

The Stroop Effect

The brain's automatic processing of word meanings interferes with identifying the color of the ink.

Divided Attention and Dual Processing

Dual Processing: Performing two tasks simultaneously.
Divided Attention: Trying to focus on multiple tasks at once.
True multitasking is difficult for the brain, especially when both tasks require effort.

Hemineglect

Individuals ignore one side of their visual field, often due to damage in the right parietal lobe.

Brain Waves and Consciousness States

Gamma Waves: Problem solving, concentration.
Beta Waves: Alert, awake state, active thinking.
Alpha Waves: Relaxed, calm state.
Theta Waves: Light sleep, deep meditation, visualization.
Delta Waves: Deep sleep, physical restoration.

Sleep Stages and Brain Activity

Stage 1: Light sleep, characterized by theta waves.
Stage 2: Deeper sleep, characterized by sleep spindles and K-complexes.
Stage 3 & 4: Deep sleep, dominated by delta waves.
REM Sleep: Rapid Eye Movement sleep, brain activity similar to wakefulness, dreams occur in this stage.

REM vs. NREM Sleep Across Ages

Infants: Spend more time in REM and NREM sleep.
Adults: Sleep 7-8 hours, with about 20-25% in REM sleep.
Elderly: Sleep less, with reduced REM sleep and lighter sleep.

Altered States of Consciousness

Meditation: Shifting focus inward, leading to altered perception and relaxation.
Hypnosis: A highly focused, suggestible state where perception and behavior can be altered.
Psychoactive drugs: Substances that alter perception, mood, and thought patterns.
Sleep: A naturally occurring state with distinct stages.

Key Sleep Terminology

K-Complex: A large wave in stage 2 sleep that helps protect the sleeper from waking.

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Description

Test your knowledge on the concepts of depolarization, repolarization, hyperpolarization, and the all-or-none law in neurons. This quiz also covers refractory periods and synaptic transmission, critical components in understanding neuronal communication. Perfect for students studying neuroscience or related fields.