Chapter 2 - Cognitive Neurosciene Flashcards
Cognitive Neuroscience
study of the neural mechanisms of cognition and behavior
focuses on role of brain mechanisms
Dualism
postualted by Descartes
existence of separate non-physical mind
mind and brain are two separate things
Materialism
mind is entirely a product of the brain
every action and mental event has a neural basis
Organization of Brain - Left and Right Hemispheres
left hemisphere: language functions
right hemisphere: visuospatial tasks
Organization of Brain - Corpus Callosum
massive bundle of axons connecting the
two hemispheres
allows for interhemispheric communication
Organization of Brain - Cerebral Cortex
thin, folded layer of neurons in the outer layer of the hemispheres
Organization of Brain - Cerebellum
thought to only play a role in motor control and coordination
more recently implicated in other cognitive functions
Lobes of the Hemispheres
- occipital lobe - visual perception
- temporal lobe - complex perception, memory, language
- frontal lobe - thinking, planning, decision making
- parietal lobe - visuospatial functions
Functional Specialization
different brain areas serve different perceptual and cognitive skills
specialized areas work together to in a network, many tasks require a network of interconnected areas
Nervous System
neurons: cells specialized to
create, receive, and transmit
information in the nervous system
parts of a neuron:
- dendrites
- cell body
- axon
- axon terminal
How Neurons Communicate
neurons have membrane potential and have ions (charged particles) inside and outside of neuron
neuron receives signals from other neurons
signals can either be excitatory (positive, more likely to send action signal) or inhibitory (negative, less likely to send action signal)
if neuron receives excitatory input:
- sends signal (action potential)
- propagates down axon
- reaches axon terminal
- sends signal to next neuron in the chain
Synapse
space between axon terminal buttons of one neuron and
dendrite or cell body of another
when the action potential reaches the end of the axon, synaptic vesicles release chemical neurotransmitters
synapses can change with learning and experience and their strength affects connection between neurons
Imaging: Correlation vs Causation Problem
imaging simply reveals a correlation between processing/stimulus and brain activity, cannot make reverse inference
brain activity in a region does not mean the region is necessary for the
cognitive task or perception
Imaging vs Stimulation
brain stimulation methods stimulate or disrupt activity to study causation of perceptual or cognitive function
because experimenter is controlling brain activity, puts them in a stronger
logical position to infer causation
Stimulation/Inhibition: Transcranial Magnetic Stimulation (TMS)
brief magnetic pulses are emitted by a coil next to the skull
produces a magnetic field that can affect brain activity in the underlying cortex
can create a temporary functional “lesion,” can also create increase neural activity
because experimenter has control, it reveals a causative, rather than a correlational brain–behavior link
Pitcher et. al (2009)
subjects had to make same-different decisions for two stimuli shown one at a time
TMS applied to one of three visual processing areas
disruption of performance specific to stimulus
faces: right occipital face area
objects: right lateral occipital area
body parts: right extrastriata body area
suggests different brain areas are involved in identification of different types of stimuli
Stimulation/Inhibition: Transcranial Direct Current Stimulation (tDCS)
similar purpose to TMS
delivers small electrical currents to the scalp
current can increase or decrease neural activity in underlying area
weaker effect than TMS
findings suggest if an area is preactive or primed, more neurons will fire in that area
Fregni et al. (2005)
effect of tDCS on working memory
applied tDCS to part of frontal lobe involved in working memory
used a 3-back task to measure working memory
see a series of letters
press a key if the current letter is the same as 3 letters before
Neuropsychology
studies behavioral impact of brain damage
damage can be done naturally by strokes or illness, or unnaturally by trauma or surgery
areas controlling a brain function can be determined by mapping out
overlapping areas of damage in patients with the same deficit
allows for identification of what functions are served by specific areas of the brain
Neuropsychology: Double Dissociation
when damage to one part of the brain causes one function to be absent
while another function if unaltered, and damage to another area causes
the reverse pattern
