Chapter 1: Foundations Flashcards
Sensation
initial process of turning physical features/ stimuli into electrochemical signals that are sent to brain to be processed
Senses
physiological process of turning environmental stimuli into electrochemical signals
Study of perception is highly interdisciplinary
- Psychology
- Physics and Chemistry
- Cognitive neuroscience
- Neuropsychology and neurology
- Computer science and artificial intelligence
- Biomedical engineering
- Philosophy
Study of perception is highly interdisciplinary
- Psychology- perception is aspect of how mind works
- Physics and Chemistry- involved the study of things that can be sensed
- Cognitive neuroscience- study of brain, cognition, and behavior
- Neuropsychology and neurology- study of brain damage and how affects perception
- Computer science and artificial intelligence- building computational devices that can be model perception and response to world
- Biomedical engineering- brain imaging and building sensory prosthetics
- Philosophy- subjective awareness, knowledge, and consciousness
Representation
info in brain used to represent objects/ events to store them in memory and to support thoughts and actions
Stimuli
objects and events that are perceived (distal) and the phenomena produced (proximal)
Perception
initial sensory signals are used to represent objects and events
Process of Perception
1. 2. 3. 4. 5.
Process of Perception
- Distal Stimuli- perceived object/ event
- whatever physical energy is coming from
- furthest away from body - Proximal Stimuli
- physical phenomenon evoked by distal stimuli that impinges on specialized cells
- physical energy - Proximal stimuli converted to neural signals, which are sent to brain
- Sensory Receptors- specialized neurons that convert proximal stimuli to neural signals - Signal processing in the brain
- Conscious awareness
Where perception begins:
Transduction: physical signal -> neural signal
Neural Code
pattern of neural signals that carry info about stimulus and can be representation
Psychophysics
relation between psychological phenomena and physical stimuli
Bottom-Up Processing
info contained in neural signals from receptors
Top- Down Information
observer’s knowledge, expectations, and goals, which can affect perception
Gustav Fechner
- German experimental psychologist
- Published ‘Elements of Psychophysics’
Absolute Threshold
minimum intensity of physical stimulus that can be detected by observer
Psychometric Function
curve that relates measure of perceptual experience to intensity of physical stimulus
Method of Adjustment
participant observes and controls stimulus to change intensity of stimulus
- can come up with average for individual after many trials
- ie. dot slider
Method of Constant Stimuli
participant is repeatedly given fixed set of stimuli of different intensities and then indicates if stimulus was detected
- researcher controls stimulus
- ie. yes, no clicker
Staircase Method
participant says whether or not they perceive stimulus and are presented stimulus that is one step higher or lower accordingly
Aristotle Illusion
cortical mapping in different area that’s not what was previously experienced, you perceive it differently
Difference Threshold/ Just Noticeable Difference (JND)
minimum difference between two stimuli that allows an observer to perceive that two stimuli are different
Ernst Weber
carried out a large number of experiments to estimate the JND for different intensities if standard stimuli for different perceptual dimensions
Psychophysical Scaling
process of measuring how changes in stimulus intensity relate to changes in the perceived intensity
Steven’s Power Equation
S= cI^n
n<1
- response compression
- underestimation
- ie. brightness
n>1
- response expansion - overestimation - electric shock
Johannes Muller
- Perception based on neural activity
- “Law of specific nerve energies” states that kinds of perception are dependent on which neurons are activated, not what is activating them
Charles Sherrington
- Fundamental principles of brain function, including neuronal communication and networks
- Neuron Doctrine- principle that perception depends on combined activity of many specialized neurons, each of which responds to specific aspects of stimulus
Wilder Penfield
- Constructed “touch map” (touch brain –> see body movement) showing how perceived location of body surfaces touched corresponded to location of brain neural activity
- Neuroscientists in 1950s to 1960s found that:
- Individual neurons in frog’s brain respond to specific visual stimuli (vagus nerve stimulation)
- Changes in physical stimuli produce corresponding quantitatively precise changes in neural activity
Typical neuron
distinguished from other types of cells:
- communication and information movement is different from other cells
- hyperconnectivity (lots of connections across synapses)
Ions in resting membrane potential
- Higher Na+ outside axon
- Higher K+ and A- inside axon
Transmitting signals between neurons
- Synapses can excite or inhibit the cells they influence
- Excitatory: Post-synaptic (receiving) cells depolarize (more positive)
- Inhibitory: Post-synaptic cells hyperpolarize (more negative)
Binding of NTs at excitatory synapses causes ___ ion channels to open, allowing ___ ions to enter the neuron and creating an ____
Na+, Na+, EPSP
Binding of NTs at inhibitory synapses causes ___ ion channels to open, allowing ___ ions to enter the neuron and creating an ____
Cl-, Cl-, IPSP
The Human Brian
- Size
- 300 billion neurons organized into dozens of anatomically and functionally distinct regions
- Number of synapses in the brain exceed 100 trillion
- Brain weighs about 1.3 kg
- Gray matter outside, white matter inside - Divisions and connections
- Major divisions: right and left cerebral hemispheres
- Major hemispheric connection: corpus callosum
- Most important subcortical structure: thalamus
- most neural signals originating in sensory organ pass through thalamus on the way to cortex
Cognitive Neuropsychology
damage to a particular area of the brain typically causes a deficit in a specific cognitive or perceptual function
- info about structures when dysfunction is occuring
- depends on modularity- complex tasks require coordination among many modules
- Functional modularity: each cognitive system has a module
- Anatomical modularity: certain brain areas have a cognitive function
Pierre Paul Broca
discovered that speech production center of brain is located in region of left frontal lobe (Broca’s area)
Dissociation
pattern of brain damage and impaired function in which damage to some specific brain region is associated with impairment of some specific function but not with impairment of another function
Double Dissociation
pattern of brain damage and impaired function in which damage to some specific brain region is associated with impairment of some specific function (A), but not with impairment of another function (B) along with a pattern in which damage to different region is associated with impairment of function B but not with impairment of function A
Functional Neuroimaging
- techniques to measure healthy brain activity
- EEG- uses electric field to measure surface level activity
- MEG- uses magnetic field to measure surface level activity
- PET- measures changes in bloodflow and brain activity with radioactive substance
- can’t see changes taking place in short periods of time
- fMRI- used for detecting the changes in blood oxygenation and flow that occur in response to neural activity
- can be used to produces activation maps showing which parts of the brain are involved in a particular mental process
Diffuse Optical Tomography
- refers to emerging type of brain imaging
- senses changes in the blood oxygen level in the brain, but does so by using optical techniques
- employs array of near- infrared light sources and sensors that measure changes in the light reflected by the brain, caused by changes in blood flow
- has some advantages over PET and fMRI
