Lectures 3 & 4 (test 1) Flashcards
magnitude estimation
- power law
- scaling approach where subjects provide direct ratings of their sensation
Stevens Power Law
S = k * l^b
sensory transducer theory
the idea that transduction of the physical stimulus into a biological stimulus is the basis of the power-law
intra-modal matching
- a scaling technique
- comparing different aspects of a stimulus within a particular sensory modality
cross-modal matching
- compare stimuli from one sensory modality to stimuli of another modality
The absolute threshold can vary because…
- stimulus variation
- cognitive factors
- nervous system variability
- noise in biological system
4 possible outcomes of SDT
- hit
- miss
- correct rejection
- false alarm
hit
yes signal
yes response
miss
yes signal
no response
false alarm
no signal
yes response
correct rejection
no signal
no response
conservative criterion
tell them to expect 30% of time
liberal criterion
tell them to expect 70% of time
the large the d’
higher the sensitivity
receiver operating characteristics (ROC) curve
- plots hit vs false alarms
- provides estimates of d’
does a true threshold exist?
we cannot say it does
ROC straight line
50% hit / miss rate
d’ =0’
cannot detect sound over noise
d’=3
means almost 100% hit rate
Charles Darwin theory of evolution
suggests continuity in the structure and function of the senses and nervous system
Johannes Müller Doctrine of specific nerve energies
not aware of world around us, only aware of nerve activity
Hermann Von Helmholtz
first to successfully measure neurons transmission speed
Santiago Ramón y Cajal Neuron Doctrine
detailed neuron drawings of neurons and how hey never touch
Sir Charles Sherrington
coined term “synapse”
Otto Loewi
discovered first neurotransmitter (acetylcholine) to prove that most communicate using it and the action potential
Sir Alan Hodgkin and Sir Andrew Huxley
the discovered ionic basis for resting and action potential
afferent neurons
towards CNS
efferent neurons
away from CNS
the first step in the sensory process
transduction
transduction
conversion of external energy into an electrical signal
what creates the electrical signals?
Ion channels
Ligand-gated channels
- ion or molecule that binds reversibly
- opens a channel pore allowing ions to pass through
G-protein coupled receptor
- the ligand binds g-protein-coupled receptor (GPCR)
- GPCR activates a G-protein
- G-protein initiates a signal cascade that opens ion channels
Stretch/pressure gated channels
deformation of the plasma membrane causes the protein to change shape
membrane potential
electrical charge difference between the interior and exterior of a cell
sensory signals are relayed between neurons via _______-
synaptic transmission
excitatory
bring membrane potential above threshold
inhibitory
brings membrane potential away from the threshold
bipolar cells
- generally sensory
- both ends can send and receive info
pseudo-unipolar cells
- generally sensory
- 1 axon with 2 branches (peripheral and central)
multipolar cells
generally motor and interneurons
stimulus coding
- topographical relationship from sensory organ to primary cortical site
- receptive fields
intensity
more intense stimulus > larger receptor potential > greater AP frequency
duration
continued exposure leads to decreased awareness (clothing)
modality
sensory receptors are only sensitive to a specific type of energy
superior
above
inferior
below
posterior
behind
anterior
front
rostral (brain)
front
dorsal (brain)
on top
ventral (brain)
below
caudal (brain)
back
4 lobes
- parietal
- occipital
- frontal
- temporal
gyri
crests of folded cortical tissue
sulci
grooves that divide gyri
sensory inputs arrive at the ______ of the cerebral cortex
primary receiving area
info from more than one sense being combined
polysensory
production od perceptual experiences occur in the
cortex
cortex
- 6 laters
- around the cerebrum
basal forebrain nuclei
grey matter
Thalamus
- large paired structure
- all sensory signals get relayed here but smell
spinal cord
- the most caudal part of CNS
- transmits info to and from brain
brainstem
- auditory and taste signals enter the brain via cranial nerves of the brain stem
extracellular recording
recording voltage just outside cell compared to the inactive area
intracellular recording
recording voltage across membranes of cell
EEG
- electrode cap
- functional
- locates active areas or neurons
CT scan
- computed tomography
- x-rays passed through target
MRI
- structural
- strong magnetic field
- influences spin of atoms
- uses hydrogen rich tissues to read
fMRI
- functional
- magnetic pulses
- detect O2 demand
- too loud for auditory
PET scan
- specialized camera traces bran regions using more tracer
- glucose tracer into blood
- tracer travels to most active areas
