Neuroscience and Perception Flashcards
Requirements for neurotransmitters to bind?
The binding of neurotransmitters to receptors is specific
- Lock and key
Types of Neurotransmitters
Acetylcholine
Dopamine
Serotonin
Acetylcholine
Important transmitter between motor neurons and voluntary muscles
Dopamine
Regulates motor behavior, motivation, pleasure, and emotional arousal
Degeneration of which neurotransmitter is linked to Parkinson’s?
Dopamine
Serotonin
Plays a primary role in regulating sleep, wakefulness, and eating behavior
Copycats of Neurotransmitters
Agonist
Antagonist
Neurotransmitter: Agonist
Chemical that enhances or mimics the action of a neurotransmitter
Neurotransmitter: Antagonist
Chemical that blocks the action of a neurotransmitter
What is an example of an antagonist?
Botox or Botulinum toxin is an Ach antagonist
How do we study the brain?
Patients
Neuroimaging
Neuroimaging
Neuroimaging can be structural (what does the brain look like?) or functional (where are different types of information processed in the brain?)
What techniques for neuroimaging are there?
PET
fMRI
CT
MEG
What do all neuroimaging techniques rely on?
All techniques rely on measuring a specific type of activity (blood flow, neurotransmitter release, electrical impulse) as a proxy for neural activity itself.
Issues with neuroimaging methods
Spatial Resolution
Temporal Resolution
Invasiveness
Cost
Neuroimaging: Spatial Resolution
How close is physical proximity you can get to the target brain area
Neuroimaging: Temporal Resolution
How close in time you can get to when the neurons fire
Neuroimaging: Invasiveness
The extent to which foreign substances are introduced into the body
Neuroimaging: Cost
Most imaging techniques are rather expensive
Neuroimaging: PET, what does it stand for and how does it work?
- Positron Emission Tomography
- PET records the energy from radioactive particles bumping into the regular electrons that are in your brain. Recording more PET signals tells us that more blood flow is traveling to that region.
Compares regional cerebral blood flow between cognitive states (experimental conditions)
Neuroimaging: MRI, what does it stand for and how does it work?
- Magnetic resonance imaging
- Uses a powerful magnetic field to produce high-quality images of the brain and its structure
Neuroimaging: fMRI, what does it stand for and how does it work?
- Functional Magnetic Resonance Imaging
- Used to examine changes in ongoing brain activity (function) by measuring changes in the blood’s oxygen levels
fMRI pros and cons
Pros:
- Good spatial resolution allows for precise localization of brain activation
- Non-invasive (no known harm to subjects)
- MRI scanners are widely available at medical centers and research universities
Cons:
- Although temporal resolution (1-4 sec) is much better than PET scans, still much slower than measuring actual activity
- Very expensive
- Scanner noise is very loud
Neuroimaging: EEG, what does it stand for and how does it work?
Electroencephalography (EEG)
- EEG can record electrical activity from large populations of simultaneously active neurons at the scalp with millisecond resolution
- EEF is a direct measure of neural activity
- EEG has good temporal resolution but poor spatial resolution
EEG Limitations
- Limited spatial resolution, despite high temporal resolution
- Skull and brain tissue distort electrical fields
- Largely blind to subcortical activity (too deep to measure on the scalp)
Neuroimaging: TMS, what does it stand for and how does it work?
- Transcranial magnetic stimulation
- Strong magnets are used to briefly interrupt normal brain activity as a way to study brain regions
- Used for:
- Direct testing of function
- Treatment for some neurological and psychological conditions
Sensation
The physical processing of environmental stimuli by the sense organs
Perception
- The psychological process of interpreting sensory information (assigning meaning)
- Way that sensory information is interpreted, organized, and consciously experienced
Sensory receptors
Specialized neurons that respond to specific types of stimuli
Sensation
Occurs when sensory receptors detect sensory stimuli
Transduction
When sensory receptors detect a specific stimuli, they convert that energy into an action potential which is sent to the central nervous system.
Sensory Systems examples
- Vision
- Hearing (audition)
- Smell (olfaction)
- Taste (gestation)
- Touch (somatosensation)
- Balance (vestibular sense)
- Body position (proprioception)
- Body movement (kinesthesia)
- Pain (nociception)
- Temperature (thermoception)
Psychophysics
Methods that measure the strength of a stimulus and the observer’s sensitivity to that stimulus
Factors that influence perception: Absolute threshold
The smallest amount of stimulation needed for detection by a sense
If a dog is super sensitive, is their threshold lower or higher than a human?
If a dog is super sensitive, their threshold for detecting stimuli (e.g., sounds, smells) would be lower than a human’s. This means they can perceive stimuli that humans might not notice, due to their more acute senses.
Just noticeable difference or difference threshold
The minimum difference between the two stimuli needed to detect a difference between 50% of the time
Weber’s Law
(Delta I)/I = k
- Delta I repreesnts the difference in threshold
- I represent the initial stimulus intensity
- K signifies that the proportion of the left side of the equation remains constant despite variations of the I term
Top-down processing
When our perceptions are influenced by our expectations or by our prior knowledge
Bottom-up processing
Occurs when we perceive individual bits of sensory information (e.g. sounds) and use them to construct a more complex message
Signal Detection Theory
Response to a stimulus depends on a person’s sensitivity and on a person’s decision criteria.
Decision criteria:
Person’s experience
Expectations
Motivation
Level of fatigue
Consequences of missing
Sensory Adaptation
Diminished sensitivity as a result of constant or recurring stimuli
Factors that influence perception
- Motivation
- Beliefs, values, prejudices and expectations
- Life/cultural experiences
Factors that influence perception: Attention
- Selective attention
- Inattentional blindness
Selective attention
Focusing on one particular task or event
Inattentional blindness
A failure to perceive objects that are not the focus of attention
Change blindness
The failure to detect changes to the visual details of a scene
5 Senses
- Sight
- Hearing
- Taste
- Touch
- Smell
How does light get processed in the eye?
When light passes through the cornea and lens, it is bent so that the light waves cross and project and upside down image on the retina
- Top becomes bottom, and left becomes right
What do photoreceptors do?
Transform light into neural signals (transduction)
What does the Ganglion do?
Gather information from photoreceptors
What does the optic nerve do?
Pathway for messages to be sent to the brain.
How many rods and cons are there per eye?
- 6 million cones
- 120 million rods
Trichromatic color theory
3 different cones each sensitive to different wavelengths of light (short, medium, long)
Shortcomings of trichromatic color theory?
Does not explain negative afterimages
Opponent Process Theory
- We perceive color in terms of opposing pairs: red/green, blue/yellow, black/white
- Example: cells that are stimulated by red are inhibited by green. When green is no longer perceived, a rebound effect occurs. The previously inhibited cells are free to fire. Can be seen when staring at green for a while, when you look away, you see red.
How are images processed?
- The signal travels down the optic nerve to the brain
- Passes through thalamus
- Sent to Primary Visual Cortex
What is feature detection?
Neurons respond selectively to specific features
After the visual cortex, information is routed to which cortical areas for processing?
Dorsal - “Where pathway”
Ventral - “What pathway”
Optic ataxia
Impairments of reaching, but can still recognize objects (parietal lobe lesion)
Visual Agnosia
Impaired object recognition, but spared reaching ability
Retinal Disparity
Different retinal images each eye receives based on different perspectives. Gives 3D perspective.
Size consistency
When an object gets closer to you its image on your retina gets larger, but you still perceive it as the same size. The brain adjusts for your distance from the object when perceiving size.
Shape constancy
We correctly perceive the shape of objects even when the retinal image it casts changes as you change your viewpoint.
Brightness constancy
We correctly perceive the brightness of objects regardless of actual lighting
