Final (death) Flashcards
what are interlevel experiments used for?
to assess relevance to components and to integrate levels
bottom up experiment
intervene in some aspect of the part and map what it does to the whole (excitatory or inhibitory)
top down experiment
change behavior of whole zoom in and detect the parts (excitation)
cognitive neuropsychology
aims to understand how the structure and function of the brain relates to specific psychological processes
examples of how cog neuropsychology could be used
used psychiatric case-studies to make inferences about how healthy cog mechs work
use models of healthy cog mechs to draw inferences about mechs underlying disease
lumping strategy
things that you think are unrelated are actually one thing (ex-breathing and rusting are both oxidation)
essentially strategy of association
example of lumping strategy
boyer showed that ritualistic behavior shares qualities and have the same mechanism as the actions of people with OCD
splitting strategy
dissociation
things you thought were all one sort of thing are not just one sort of thing
example of splitting strategy
emotions dont really all hold together
(simple emotions cluster; social emotions cluster but they dont cluster with each other)
memory isn’t all the same-declarative and non-declarative memories are causally independent
two branches of memory
declarative and non-declarative
they are causally independent
declarative memory
explicit
breaks down into episodic and semantic (has a “that” clause) memories
non-declarative memory
implicit
breaks down into priming, classical conditioning and motor skills
association studies
lesion to single structure impairs performance on task A and B
infer mechanism for task A and mech for task B have either a component in common or both are causally dependent on a third thing
the projection system
episodic memory and imagination of future are thought to be related
people who have deficits in ep mem also have deficits in imagining self in future
the thought is that maybe there is ONE cognitive system, a single projection system, that is responsible for both things
this is a lumping hypothesis
problem with association
(or the lumping hypoth)
it may be hard to damage one part of brain without damaging another
i may be hard to damage JUST one cog faculty without damaging others so it could be that theres just more than one damaged thing
single dissociation
subject S is impaired on task A but not taks B
infer that A requires some component (damage in S) that B does not
Ex of single dissociation with KC
he can define words (generally), but cant remember or recognize what words he defined 3 minutes earlier
he has a digit span but once hes distracted the info is gone
there is therefore a single dissociation between semantic (which is intact) and episodic memory (which is gone)
multi task dissociation
id a set of tasks on which subject succeeds (Ts)
ID set of tasks where the subject fails (Tf)
conjecture that some cognitive faculty is required for Tf but not Ts
example of multi task dissociation with HM
declarative memory-
he fails at consciously recognizing facts and events (regardless of the type of test or material or sensory modality)
he succeeds at perceptual and motor skills, IQ tests, mirror drawing, priming, classical and operant conditioning and language
KC
motorcycle accident that left him with severe memory probs
no new semantic memory
no episodic memory
Unlike other patients (patient HM, for example), KC has his semantic memory intact
HM
had a bilateral medial temporal lobectomy to surgically resect the anterior two thirds of his hippocampi, parahippocampal cortices, entorhinal cortices, piriform cortices, and amygdalae in an attempt to cure his epilepsy
no semantic memory
able to complete tasks that require recall from short-term memory
no long-term episodic memory
modularity
cognition composed of separable capacites-not just a homogenous jelly
universality
all normal subjects share the same or similar cognitive architectures
subtractivity
brain damage can impair or delete esisting components in the system but not add cognitive abilities
no de novo reorganization
not reorganization following brain damage in a way that masks or unmasks certain symptoms
transparency
one can easily infer the function of the independent processing unit from the pattern of impaired performance
limitations of using impaired/lesioned people
n=1
premorbid psych condition often unknown
psych eval is rarely clean
damaged in only one function? (doubtful)
capgras delusion
delusion that loved ones have been replaced with replicas (imposter syndrome)
and that homes have been replaced with replicas
self as an imposter
assumptions of dissociation
modularity universality subtractivity no de novo reorganization transparency
double dissociation
ability to do A without B exists
ability to do B without A also exists
leads to a more full conclusion that A and B are independent
resource problem single dissociation
if Task B requires more cognitive capacity that Task A and S can do task A but not B than the results could look like A and B are independent when in fact they may use the same cog system but B requires more cog ability
double dissociation with crossover
Task A: Patient S performs better than patient T
Task B: Patient T performs better than Patient S
localization
Find the brain area or set of brain areas that are damaged in the case at hand; posit that the damaged area is responsible for the missing faculty
this goes back to GALL who believed in modularity
Broca later agreed saying language center is right behind the eyes
double dissociation without crossover
Patient S performs Task A better than Task B;
Patient T performs task B better than task A.
this is without crossover because patient S could be better than T on both
what happens with brocas apashia
this can happen from a stroke-there is speech comprehension but NO language prooduction
where is brocas area?
look it up
wernickes aphasia
no speech comprehension but TONS of language production-the words they say dont make sense
where is wernickes area
look it up but its toward the back of the brain
difficulties with localization
damage to one area or many? direct damage of diaschesis(-secondary effects of a primary lesion due to loss of connectivity or damage to the vasculature)
we can not know exactly where a cog function is developped
non-invasive lesions with TMS(benefits ad what it is)
TMS stands for transcranal magnetic stimulation
this is one solution to the difficulties with localization
current through a coil that makes a magnetic pulse which induces a magnetic field pulse
the changing mag field induces an Efield
E field induces current in the tissue which creates virtual patients
TMS problems
localization can be an issue, lateral spread of current and connection spread can be problems
no cell type receptor type specificity
can only hit surface level areas
inferential distance (models vs target)
how to target a location with TMS
use EEG electrode locations
guide with fMRI
deine area by its function
use control stimulation (the click of the machine during the pulse and a muscle twitces or whatever)
TMS compared to other lesion techniques (benefits)
humans short duration temporal control more precision moveable theres recovery of function valence lon term study As many people as you want (high N)
caramaza
responsible for noting the assumptions that dissociation studies have:
modularity universality subtractivity no de novo reorganization transparency
advantages using animal models in deficit studies
more control over location and extent of lesions
better pre and post mortem comparisons
n>1
more exacting controls
lesion techniques
- Aspiration and Cauterization
- Transection of Fiber Bundles
Corpus callosum.
Fornix.
White matter temporal stem. - Cooling
how might animal models fail
1) Overly Simple (Sensitization vs. Episodic)
2) Sample Bias (mice and genetics)
4) Inbreeding of Strains
5) Comparing Behavioral Tasks
Is it a simplified task? To what extent does it capture key features of the phenomenon? Does it presume idealized conditions?
How much training is required in target and model?
Is the task enviornmentally adequate?
Do we use the same or similar mechanisms to solve the same or similar tasks?
limitations of animal models
- Indirect interference
Connecting fibers
Collateral damage
Diaschesis
Specific Cell/Receptor population - Compensation: Redundancy and Recovery.
- Comparison:
Are humans and monkeys engaged in the same cognitive processes when they do the same task?
How do you decide, given inevitable differences? - LESION EXPERIMENTS ARE ONLY AS GOOD AS THE PSYCHOLOGICAL TASKS THAT GO WITH THEM.
Battery versus focused
timing of TMS stimulation
????
single unit recording (SUR)
top-down techinique
you engage the organism in behavior of interest
“method of measuring the electro-physiological responses of single neurons using a microelectrode system. When a neuron generates an action potential, the signal propagates down the neuron as a current which flows in and out of the cell through excitable membrane regions in the soma and axon. “-wikipedia
invasive
put electrode in brain
measures electrical activity in certain part of brain of a single neuron
we are measuring action potential
trilogy of techniques used in SUR
recording
stimulation within injecting current
inactivation of a whole bunch of neurons
how to do SUR
finding a cell-base w a grid, microdrive, microelectrode of metal or glass,oscillosocpe/audio amplifier
insert microelectrode/audio amplifier while behavior of interest taking place
tetrode-search of all or none amplitude of consistent shape
connectivity-orthodromic activation
the neuron recorded from it synaptically driven
antidromic actication
the neuron recorded is driven through its own axon
SUR vocab: prefferred stimulus
stim type that elicits the strongest effects on the activity of the neuron
