Sensation and Perception ch 1 and 2

What is sensory physiology? - Concerned with how sensory information is detected and processed by the nervous system

Neural processing - the interaction of many neurons as information travels through the nervous system

Dendrites - Branchlike parts of a neuron that are specialized to receive information.

Soma (cell body) - Contains nucleus and organelles; keeps neuron alive

Axon - Carries electrical activity away from soma

Axon terminal - Where signals are transmitted to other cells

Synapse - Junction/space where neurons communicate

Sensory receptor - Specialized neuron that responds to particular types of energy

When a sensory receptor receives a stimulus: - This process allows physical energy from the environment to become neural information

Recording electrode - Located within the neuron

Reference electrode - Located outside the neuron

When an axon is at rest - It has resting potential

What is an axon's average resting potential? - -70 mV

At rest, outside an axon has a higher concentration of - Na+

At rest, inside an axon has a higher concentration of - K+

Action potential - the predictable rise and fall of the electrical charge inside an axon relative to the outside

An action potential begins at around - -70 mV

An action potential rises to around - +40 mV

An action potential lasts about - 1 millisecond

Lastly, and action potential - travels down the axon

What is the basic sequence of an action potential? - Resting → Depolarization → Repolarization → Hyperpolarization → Resting

Depolarization: - The axon's charge becomes more positive

Depolarization happens when - Na⁺ rushes INTO the axon

Depolarization sequence of events: - Na⁺ enters → neuron becomes more positive → depolarization

Repolarization: - The axon's charge becomes more negative after depolarization

Repolarization happens when - K⁺ rushes OUT of the axon

Hyperpolarization: - The axon's charge becomes more negative

A type of hyperpolarization is - repolarization

Why does the neuron temporarily become more negative than its normal resting potential during hyperpolarization? - it releases too much potassium

Action Potential: Know the Sequence -

1. Rest

Around −70 mV

2. Na⁺ enters

Charge becomes more positive

3. Depolarization

Potential rises toward +40 mV

4. K⁺ exits

Charge becomes more negative

5. Repolarization/hyperpolarization

6. Return to resting potential

How does action potential intensity affect size? - it stays the same

What does a stronger stimulus mean? - faster firing rate

Refractory Period - the interval between one action potential and another; limits firing rate

Electrical signals occur when - ions cross the neuron's membrane

Spontaneous activity - Neuron firing without stimulation

When an action potential reaches the end of the axon, what happens? - It causes the release of neurotransmitters

Synapse: - The small space/junction between neurons

Neurotransmitters: - Chemicals that carry information across the synapse

Presynaptic neuron - The neuron releasing the neurotransmitter

Postsynaptic neuron - The neuron receiving the neurotransmitter

Excitatory neurotransmitters - Cause depolarization, make the neuron more positive, increases likelihood an action potential

Inhibitory neurotransmitters - Cause hyperpolarization, make the neuron more negative, decrease the likelihood of action potential

Summation - neurons "sum" excitatory and inhibitory inputs

The neuron's response depends on - the balance between excitation and inhibition

If excitation > inhibition: - Higher firing rate

If inhibition > excitation: - Lower or nonexistent firing

Sensory coding - how neurons represent characteristics of the environment

How does the brain use neural activity to represent what we perceive? - Specificity coding, Sparse coding, or Population coding

Specificity Coding (Grandmother cell hypothesis) - One neuron = one stimulus/concept

Problem with specificity coding - You would theoretically need a dedicated neuron for every stimulus/concept you've encountered

Sparse Coding - Small group of neurons = stimulus

Population Coding - Large group of neurons = stimulus

Phrenology (Franz Joseph Gall) - pseudoscience claiming mental faculties could be determined from bumps on the skull

Magnetic Resonance Imaging (MRI) - What does the brain LOOK like?

fMRI - What is the brain DOING?

Modularity - the idea that specific brain areas are specialized for specific types of stimuli or functions

Aphasia - a disorder involving comprehension or expression of language

Broca's aphasia - Have difficulty producing speech and forming complete sentences, but can understand speech

Wernicke's aphasia - Have difficulty understanding speech and can produce complete sentences, but may produce speech that doesn't make sense

Why Does Aphasia Support Modularity? - Damage to different brain areas produces different language problems; therefore, different brain areas appear to have specialized functions

Distributed representation: - The brain represents information through patterns of activity distributed across the cortex, rather than relying on only one brain area

Distributed representation example: - putting your hand on a hot stove

Structural connectivity: - The physical "road map" of fibers connecting different areas of the brain

Functional connectivity: - The relationship/correlation between neural activity in different brain regions associated with a function

Resting-State fMRI - Researchers can measure brain activity when the brain is not engaged in a particular task

If two regions have highly correlated activity: - High functional connectivity

If two regions have low correlated activity: - Low functional connectivity

What Is the Mind-Body Problem? - How does physical brain activity produce subjective conscious experiences?

Is there a current answer to the mind-body problem? - no