Effects of brain damage and brain stimulation as a window into the mind Flashcards
What is the issue of causality?
Just because brain activity is associated with a task does not mean that the activity causes the observed behaviour
What can we observe to determine causality?
neurosurgery, stroke, brain trauma or tumours, neurodegeneration, infection of brain tissue
What is neurosurgery?
removal of brain tissue for treatment of neurological or psychiatric disorders (most often epilepsy)
What is neurodegeneration?
Degeneration of brain tissue in dementia
What is neuropsychology?
Examines the effects of brain damage on abilites and behaviour
What did Broca determine that Tan had?
a lesion caused by syphillis in the left inferior frontal lobe
What is the corpus callosum?
white matter tracts (numerous axons) connecting two hemispheres
What is callosotomy?
cutting through the corpus callosum to limit spread of epileptic activity
What is the WADA test?
reversible numbing of the left hemisphere via the sodium amytal injection
Where is the localisation of language heavily based
the left hemisphere
What is hemispatial neglect?
being able to see everything but stop paying attention to the left visual field
How did HM have anterograde amnesia?
formed almost no new episodic memories
How did HM have retregrade amnesia?
recall early childhood but not years immediatly before the surgery
What in HM were close to normal?
Procedural memory and lexical memory
What are the key approaches in neuroimaging?
To see where a task is localised or to see if a task has a different pattern of activation from another condition
What are the key approaches in neuropsychology?
Classical neuropsychology and cognitive neuropsychology
What is classical neuropsychology?
Research primary concerned with localisation
What is cognitive neuropsychology?
Concerned with determining the cognitive architecture by identifyinf behavioural performance that relies on qualitatively similar or on qualitatively different processes (regardless of the exact location of damage).
Relies on the logic of dissociations
What is an example of dissociation?
whether the recognition and writing of vowels (e.g. a, e) rely on different psychological process from the recognition and writing of consonants (e.g. t, r)
What is single dissociation?
when a manipulation leaves one cognitive function (say, A) intact whilst severing another (say, B).
What is double dissociation?
one type of item (here vowels or consonants) is generally more resilient to the effects of damage
What is an example of single dissosiation?
Cubelli and spelling errors with vowles?
What is an example of double dissociation?
Kay and Hanley- errors in vowels and constonants but worse in the latter
Why is a group study better than a single case?
Reduces the contribution of irrelevant factors
What is a limitation of neuropsychology?
lesions resulting from trauma or neurological degeneration are rarely anatomically selective
How does TMS work?
- large current is discharged into a coil
- The current generates a rapidly changing (increasing) magnetic field around the coil
- In the cortex, the magnetic field generates electric (ionic) current through neurons’ membranes
What is phosphenes?
perception of flashing aptterns
What can we infer from the effects of TMS?
- functional-anatomical inference
- chronometric (temporal) inference
- process interaction inference
What are advantages of TMS
- capacity to determine causation
- good spatial resolution
- extreme temporal resolution
- different conditions to be compared within the same group of subjects
