Chapter 1 Foundations Flashcards
1
Q
Sensation
A
physical features —> electrochemical signals with specialized nerve cells —> to brain for processing
- process of transforming physical stimuli to electrical (neuronal) signals
- Mediated by specialized nerve cells called receptors
2
Q
Senses
A
Physiological functions; own specialized cells, tissues, and organs for converting environmental features —> electrochemical signals —> brain
3
Q
Perception
A
Initial sensory signals are used to form mental representations of the objects and events in a scene so they can be organized, stored in memory and used in thought and action
- interpreting electrical signals for conscious awareness
- Brain’s goal is to accurately represent the distal stimuli based on inferences about the information it gets from the proximal stimuli
4
Q
Distal stimuli
A
objects and events that are perceived
*Things out there in the world eg tiger
5
Q
Proximal stimuli
A
physical phenomena they produce
- Physical things that actually make contact with our sensory receptors eg light or sound waves, odor or taste molecules, sharp teeth
- These are what initiate neural signals in sensory receptors
6
Q
Neurons
A
cells of the nervous system that produce and transmit information- carrying signals
7
Q
Neural signals
A
information-carrying electrochemical signals produced and transmitted by neurons
8
Q
Sensory receptors
A
specialized neurons that convert proximal stimuli into neural signals
9
Q
Top-down information
A
observer’s knowledge, expectations and goals, which can affect perception
*Processing based on the perceiver’s previous knowledge and expectations (cognitive factors) and the entire context of a stimulus
10
Q
Bottom-up information
A
The information contained in neural signals from receptors
*Processing based on incoming stimuli fro the environment
11
Q
Transduction
A
Transformation of a physical stimulus into neural signals
12
Q
Neural code
A
pattern of neural signals that carries information about a stimulus and can serve as a representation of that stimulus
13
Q
Psychophysics
A
field of study concerned with relating psychological experience to physical stimuli
14
Q
Natural selection
A
Darwin: biological evolution which adaptive traits are more likely to be passed on to offspring through genetic inheritance and to become increasingly prevalent in a population
15
Q
Neuron doctrine
A
Perception depends on the combined activity of many specialized neurons, each of which responds to specific aspects of a stimulus, called trigger features
16
Q
Cell membrane
A
a cell structure that separates what’s inside the cell from what’s outside the cell
17
Q
Cell body (Soma)
A
contains nucleus
18
Q
Dendrites
A
receive signals from other neurons
19
Q
Axon
A
conducts neural signals to the axon terminals, for transmission to other neurons
20
Q
Axon terminals
A
ending of axon, where neural signals are transmitted to other neurons
21
Q
Nerve
A
a bundle of axons that travel together from one location in the nervous system to another
22
Q
Action potential
A
electrochemical signal that begins in the dendrites of a neuron and travels down the axon of the axon terminals
23
Q
Ion
A
atom that has an imbalance in the number of protons and electrons and that therefore has an electric charge (positive/negative charge)
24
Q
Membrane potential
A
difference in electrical potential across the cell membrane, due to a difference in the concentrations of positive and negative ions inside and outside the cells
25
Resting potential
membrane potential when a neuron is a t rest (-7 mv)
* Higher concentration of negatively charged ions inside the cell than outside
* Isn't generating neural signal
26
Single-cell recording
technique used to measure the membrane potential with electrodes placed inside and outside cell membrane
27
Ion channels
small pores in the cell membrane of neurons through which certain ions can flow into or out of the cell
*Voltage-gated: open when the membrane potential changes sufficiently and ions can pass through only when channels are open
28
Depolarization
Inflow of positively charged ions causes the membrane potential to become markedly more positive (-70--> 0--> +30peak)
29
Hyperpolarization
Briefly exceeds resting potentials
30
Refractory period
Following an action potential; a brief period during which a new action potential cannot be initiated
31
Firing rate
rate at which a neuron produces action potentials, usually expressed in "spikes per second"
*Neural code conveying useful in about stimulus into neural activity
32
Baseline firing rate
neuron's low rate of spontaneous firing at fairly random intervals in the absence of any stimulus
33
Threshold
stimulus's minimal intensity---> increase in firing rate above baseline rate until the neuron is firing at its maximal rate
* Probabilistic, not all-or-none
* The same stimulus may be detected on one trial and not the next.
* Threshold is the intensity that results in detection on 50% of trials
34
Synapse
a tiny gap between the axon terminal of one neuron and the dendrite/cell body of another neuron
35
Presynaptic membrane
membrane at the axon terminal of a neuron producing an action potential
36
Postsynaptic membrane
membrane of dendrite or cell body receiving a neural signal
37
Synaptic vesicles
within axon terminals, tiny sacs that contain neurotransmitter molecules
38
Neurotransmitters
chemical substances involved in the transmission of signals between neurons; neurotransmitter molecules released into a synapse by the neuron sending a signal bind to receptors on the neuron receiving the signal
39
Receptors
neurotransmitter molecules fit into or bind to
| *Certain ligand-gated ion channels in postsynaptic membrane to open---> potential charge---> action potential
40
Excitatory neurotransmitters
neurotransmitters that have an excitatory effect on the postsynaptic neuron, depolarize membrane potential---> increase probability that an action potential will be generated in postsynaptic neuron
41
Inhibitory neurotransmitters
inhibiting effect on postsynaptic neuron, hyperpolarizes membrane potential ---> decrease probability of action potential
42
Excitatory postsynaptic potential (EPSP)
effect of an excitatory neurotransmitter, making the postsynaptic neuron's membrane potential more positive (increase Na+)
43
Cerebral hemispheres
Two most important divisions of the brain; separated by the longitudinal fissure
44
Corpus callosum
a large bundle of axons that constitutes the major connection between the two cerebral hemispheres
45
Gyrus (gyri)
elongated bump on the surface of the cerebral hemisphere
46
Sulcus (Sulci)
Indentation between two gyri on the surface of the cerebral hemispheres
47
Inhibitory postsynaptic potential (IPSP)
effect of an inhibitory neurotransmitter, making the postsynaptic neuron's membrane potential more negation (increase CI-)
48
Frontal lobe
one of the four lobes of each cerebral hemisphere; separated from temporal lobe by lateral sulcus and from and from parietal lobe by central sulcus
49
Temporal lobe
separated from the frontal lobe and parietal lobe by the lateral sulcus
50
Parietal lobe
separated from the frontal lobe by the central sulcus; from temporal lobe by lateral sulcus; and from occipital lobe by the parieto-occipital sulcus
51
Occipital lobe
separated from the parietal lobe by the pareto-occipital sulcus
52
Cerebral cortex
outermost layer of cerebral hemispheres; about 2-4 mm thick and consisting mostly of gray matter
53
Gray matter
cell bodies of neurons making up the cerebral cortex
54
White matter
myelin-covered axons of cortical neurons, making up the interior parts of the cerebral hemispheres; these axons connect neurons located in different parts of the cerebral cortex
55
Thalamus
most important subcortical structure involved in perception, most neural signals pass through the thalamus on their paths from the sensory organs to cortex
56
Cognitive neuropsychology
investigation of perceptual and cognitive deficits in individuals with brain damage in order to discover how perception and cognition are carried out in the normal, undamaged brain
57
Modularity
idea that the human mind and brain consist of a set of distinct modules, each of which carries out one/more specific functions
58
Dissociation
in cognitive neuropsychology, a 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
59
Double dissociation
in cognitive neuropsychology, a pattern of brain damage and impaired function in which damage to some specific brain region is associated with impairment of some specific function
60
Assumption of cognitive uniformity
the assumption that the functional organization of human cognition and of the brain is essentially the same in everyone
61
Functional neuroimaging
array of techniques for measuring brain activity in healthy volunteers carrying out carefully designed tasks (perceptual and cognitive)
* Measuring electrical and magnetic fields produced by populations of active neurons
* Measuring changes in blood flow and blood oxygenation that accompany brain activity
* Rely on modularity and cognitive uniformity
62
Electroencephalography (EEG)
functional neuroimaging technique based on measurement of the electrical fields associated with brain activity
63
Magnetoencephalography (MEG)
functional neuroimaging technique based on measurement of the magnetic fields associated with brain activity
64
Positron emission tomography (PET)
measurement of changes in blood flow associated with brain activity, using a radioactive substance introduced into the blood
* 3D image with two scans of viewing different pictures
* Cannot measure changes happen over short periods
65
MRI
Magnetic properties of molecules occur naturally in body to produce high resolution, 3D images, of bodily structures and internal features
*Level of oxygen changes in blood ---> Image neural activity in brain over time
66
Structural MRI
Single static "snapshot" of organs, bones, joints
67
Functional magnetic Resonance Imaging (fMRI)
measurement of changes in blood oxygenation associated with brain activity
*High resolution 3D every 2-3 seconds
68
Absolute threshold
minimum intensity of a physical stimulus that can just be detected by an observer
*Smallest amount of energy needed to detect a stimulus
69
Method of adjustment
"Quick and dirty"
* participant observes a stimulus and adjusts a knob that directly controls the intensity of the stimulus
* Repeat several times and get the average
70
Method of constant stimuli
the participant is presented with a fixed set of stimuli covering a range of intensities that are presented repeatedly in random order, and the participant must indicate whether or not each stimuli was detected
71
Psychometric function
a curve that relates a measure of perceptual experience to the intensity of a physical stimulus ---> S-shaped
* a function to the relation between intensity and % detection
* A level of physical stimulus and a level of perceptual response; estimate threshold
72
Staircase method
participant is presented with a stimulus and indicates whether it was detected, and based on that response, the next stimulus is either one step up or one step down in intensity
73
Difference threshold (Just noticeable difference "JND")
Minimal difference between two stimuli that allows an observer to perceive that two stimuli are different
* Standard stimulus: remains constant
* Comparison stimulus: varies from one trial to the next
* Smallest detectable difference between two stimuli
* Size of JND varies with stimulus dimension and magnitude
* As magnitude of physical stimulus (I) increases, so does JND
* But ratio of JND to stimulus magnitude stays constant, so JND is proportional to stimulus magnitude, rather than being a fixed amount
74
Weber's Law
relationship between intensity of a standard stimulus and the size of JND
*JND=KI (K=experimentally determined constant; I= intensity of standard stimulus)
75
Weber fraction
the constant K
| K= JND/I
76
Psychophysical scaling
process of measuring how changes in stimulus intensity relate to changes in the perceived intensity
77
Fechner's Law
statement of how the perceived intensity of a stimulus changes as its physical intensity changes (S=K IN I/I0)
* S= perceived intensity; K= Weber fraction
* I/I0= ratio of stimulus intensity I , to intensity I0 of same stimulus at absolute threshold
* Low intensity stimulus ---> need increase in physical intensity
* Assumed JNDs were basic mental units
* Perceived magnitude (S) is proportional to the logarithm of physical stimulus intensity (I)
78
Magnitude estimation (scaling)
assigns an arbitrary number to represent the intensity of a standard stimulus, and then the participant assigns numbers to other stimulus to indicate their perceived intensity relative to the standard
79
Stevens power law
Relationship between physical intensity of a stimulus (I) and its perceived intensity/magnitude (S)
* Power function: S=CI^n
* Brightness: n1= decelerating; response expansion
* Electric shock: n>1 = accelerating
* Line length: n=1 =straight line
80
Noise
Random variation in the number of action potentials produced by neurons in response to a fixed sensory stimulus
* Variation in response from trial to trial
* Width of best fitting normal distribution
* External vs. Internal
81
Hit
"Yes" and signal presented
82
False alarm
"Yes" + signal not presented
83
Miss
"No" + signal presented
84
Correct rejection
"No" and signal not presented
85
Receiver operating characteristic (ROC)
Curve representing quality of participant's performance
* Left + Top = better performance
* Right + Low= Guessing/bad
86
Decision-making bias
participant's tendency to be liberal/conservative in deciding whether a signal was detected; indicated by value of participant's decision criterion
87
d (d-prime)
Difference between mean of curve showing strength of perceptual evidence when no signal is presented; depends on physical intensity of signal and participant's perceptual sensitivity, but not on participant's decision criterion
88
Why study Sensation & Perception?
* Lead to practical applications
* Helps us understand our own biology
* Self-discovery
* Intellectually exciting
* Models of how bran system work
* Cool demos and illusions
89
External noise
variation in physical stimulus strength from one trail to another
*Eg different numbers of photons in successive light flashes
90
Internal noise
Variation in biological response within the receptors and neural pathways (even if stimulus didn't vary)
*Eg different numbers of vesicles available to release neurotransmitter at a synapse on successive trials
