Exam 2 Flashcards
nervous system as a box-and-arrow diagram
hierarchy
-shows up in both perception and action
-perception is built from simple features that get put together, a homonculus decides what to do, then tells a motor system to do it
-pandemonium model
population density
Records spike trains of multiple neurons over the same trials
primary motor cortex
represents movement tactics
spike count rate
spikes/time of a single neuron, measured in Hz
spike density
Firing rate of one neuron over multiple trials; time bins are used to obtain temporal information
Premotor (PMA) & Supplementary Motor cortex (SMA)
master strategist
motor cortex
-motor cortex and other cortical ares support motor planning oin the brain and allow excecution and planning of movement
central sulcus
divides motor from somatosensory cortex
cerebellum
assist in primary motor cortex’s tactics, smoothing out movements and doing constant error correction
basal ganglia
-involved in rewarding aspect of movement and in help cortex sequence and choose movements (strategy)
-A group of nuclei lying deep in the subcortical white matter of the frontal lobes that organize motor behavior.
M1
-primary motor cortex
-has somatotopic map of muscles
-more neurons for parts that have lots of control (tongue, hands)
motor neurons in the motor cortex
synapse on motor neurons in the spinal cord
activated by sensory input
Prefrontal cortex
decides what movements to make + more
motor neurons in the spinal cord
-synapse on muscle cells and use firing rate code to determine strength of muscle contraction
ventral stream
object identity is detected and processed
dorsal stream
object position
synapses in spinal cord
immediate reflexes
synapses in parietal cortex
planned behavior
Bob Wurtz
-monkey get juice for good performance
-saw spike rates increase when a monkey is developing its intention to make a movement
-spike counting is a way to explain what we saw
-the relationship between speed and accuracy is usually observed
population coding
-the idea that there is not a single neuron for any given action or sensation
-whole population acts collectively to encode information
-each neuron “votes” for a given movement
-tuning curves define which movement the neuron votes most strongly for
-think of vectors being added to decide a final movement
Superior Colliculus
-vector representations of space are topographically organized in the superior colliculus
combination of microstim & evidence
-eye movements reflect vector sum of evidence and microstim
-shows how evidence for a bigger choice has a bigger behavioral effect
-brain uses vectors to code movements
-uses populations to represent those vectors
lower motor neuron
a motor neuron that directly innervates muscle
Motor program
the plan to produce a particular motor action, such as writing one’s name, that occurs independently of the effectors used to carry out the movement.
Upper motor Neuron
A neuron that gives rise to a descending projection that controls the activity of lower motor neurons in the brainstem and spinal cord.c
cocktail party effect
you can’t filter out others’ conversations but you’ll notice your own name
attentional blink
-accuracy for 2nd target dips after a first target is detected
Attention
-attention is the control you exert over the informstion flowing in your mind
-you can open gates for one stream of thought, but only by closing the gates for others
-neurally, it seems attention must require some form of inhibition to silence active neurons
Information processing models of attention
-subjects in dichotic listening can accurately report words in the attended channel
-supports early selection theories of attention
-supports more a theory of relative attenuation at an early stage, rather than all-or-none gating
EEG
can answer questions about late vs. early selection
effects of attention on perception
-you can bias activity in a brain area to boost attention to whatever that brain ares represents
Posner task: endogenous attention
-you can use a cue to deploy covert attention
-that speeds reaction time
endogenous:
some internal state is used to voluntarily maintain attention
Exogenous
something external grabs our attention
fMRI
evidence for attention biasing of perceptual processing areas (sending those circuits excitatory signals that boost their sensitivity to sensory signals
pop-out
-exogenous attentional effect
-visual “pop-out” occurs when the target differs in a single feature (singleton)
-does not occur when target is the conjunction of 2 different festures
frontoparietal control network
attentional control
stroop model
-neural network model
-similar to pandemonium model
-information travels only upward
-info from tasks demand units biases processing
ERP responses
-three different “time scales” of ERP responses
-auditory evoked responses in EEG (responses evoked by an auditory tone)
-brain-stem evoked potentials: not effected by attention
-Midlatency responses: affected by attention
-late waves (N1, P3): affected by attention
-MEG shows where attention affected efect is occuring: primary auditory cortex
N1 Effect
attention boosts the N1, and early effect
P300 (P3) effect
attention boosts the P3
-A large positive ERP wave elicited by stimuli that are surprising, are of an infrequent event type, or are task-relevant targets, usually when occurring within a stream of other sensory events; typically peaks between 300 and 500 milliseconds after the stimulus.
Biasing
-at neural level attention = biasing
-sending non-perceptual inputs to a perceptual area to boost activation or increase that area’s sensitivity (‘gain”) to perceptual inputs
N2
the second wave, N2, reflects top-down driven neural activity that “re-enters” extrastriate visual cortex
ERPs & fMRI/PET
-data that shows how attention biases processing in perceptual areas
-fMRI shows even more clearly than MEG where attention is modulating activity
P1
the first wave, P1 reflects bottom-up stimulus processing
boosting
-attended to tuning curves
Area MT (middle temporal area)
-medial temporal lobes form new episodic memories
Rapid serial visual presentation (RSVP)
-someone doing the RSVP task with stimuli in center of a screen, motion in the peripheral visual field evokes less motion processing activity when the task in the center is hard vs. easy
auditory N1
The first major negative ERP wave elicited by an auditory stimulus, arising mainly from secondary auditory cortex and peaking at about 100 milliseconds after the stimulus; can be strongly modulated by auditory spatial attention.
Brainstem evoked response
Also called auditory brainstem response (ABR). A series of small electrical brain waves that are elicited during the first 10 milliseconds after onset of a brief auditory stimulus and that can be detected at the scalp. BERs reflect activity in the auditory brainstem nuclei as the sound stimulus information reaches them in sequence via the auditory afferent pathways.
Mismatch negativity (MMN)
A negative ERP wave peaking at about 150 to 200 milliseconds following a deviant stimulus in a stream of otherwise identical stimuli (usually sound stimuli).
reentrant process
-following a stimulus or event, a process in which neural activity is fed back to the same brain region activated earlier in the processing sequence.
binocular rivalry
The bi-stable visual experience that occurs when the right and left eyes are presented with incompatible or conflicting images and visual perception alternates between the two images every few seconds.
cellular mechanisms of memory
-LTP comes from receptor trafficking at synapse
-the more calcium allowed into the dendrite, the more glutamate receptors will eventually populate the dendritic membrane, leading to stronger EPSPs
memory involves
-encoding, storage, and retrieval
medial temporal lobes
-essential for making new episodic memories
