2: The Lesioned Brain Flashcards
how does TMS work?
a means of disrupting normal brain activity by introducing neural noise – ‘virtual lesion’, the current created a change in the electrical charges of someone’s brain, causing changes in behaviour
what are the 4 advantages of TMS?
- interference/virtual lesion technique.
- transient and reversible
- control location of stimulation
- establishes a causal link of different brain areas and a behavioural task
define: transient
temporary
which hemisphere if the brain used to be associated with language?
left - people are now though of to be predominately bilateral
what area if the brain is associated with speech?
Wernicke’s area
how do people perform at word-matching tasks when their dominant vs non-dominant speech hemisphere is stimulated (TMS)
left dominant were a lot slower if you stimulate the left side of the brain and the right sides were faster (& vice versa for right stimulation)
Improved RT for opposite stimulation: this could be because stimulating the weaker area inhibits the interference it may bring
what are the 3 types of TES?
Transcranial direct current stimulation - tDCS
Transcranial alternating current stimulation -tACS
Transcranial random noise stimulation - tRNS
how does TES work?
TES uses low-level (1-2 mA) currents applied via scalp electrodes to specific brain regions.
what effect can tDCS have on the brain?
When applied in sessions of repeated stimulation, tDCS can lead to changes in neuronal excitability that outlast the stimulation itself.
which conditions is TES used in treatment for?
migraines, dementia, stroke, Parkinson’s disease, neglect, depression, schizophrenia, OCD, eating disorders
what are the 3 types of tDCS?
Anodal
Cathodal
Sham (CONTROL)
what is the function of anodal tDCS
facilitation effects
Inhibits GABA (an inhibitory neurotransmitter) = excited response
what is the function of cathodal tDCS?
inhibition effects
Omhibits glutamate (and excitatory neurotransmitter) = inhibitory response
what is the function of sham tDCS?
control
how does lucid dreaming relate to consciousness?
A lucid dream can be thought of as an overlap between two states of consciousness, the one that exists in normal dreaming, and the one during wakefulness, which involves higher levels of awareness and control. In lucid dreaming, we transfer elements of waking consciousness into the dream
how is lucid dreaming reflected in EEGs?
When people have lucid dreams, they show gamma waves in the frontal cortex, an activity pattern that is linked to consciousness but is nearly absent during sleep and normal dreaming
how does tACS work?
tACS applies gentle electrical currents to the brain to entrain it and synchronise brain rhythms to use this route, this can train the brain to be better at tasks if they tap into the correct pathway in the brain
what is phase-locking?
the firing of neurons preferentially at a certain phase of an amplitude-modulated stimulus
how does tACS influence sleep experience?
Increased lucid dreaming
The EEG data showed that the brain’s gamma activity increased during stimulation with 40 Hz, and to a lesser degree during stimulation with 25 Hz
Insight is the awareness that one is currently dreaming improved
Dissociation is taking a third-person perspective within the dream improved
Control is control over the dream plot improved
which 2 brain measuring techniques can be combined to enhance cognitive performance?
TMS and tES
define: neuropsychology
Studying brain damaged patients
what is classical neuropsychology’s primary focus?
Primarily concerned with understanding the effects of brain damage on behavior and cognitive functions.
what is classical neuropsychology’s clinical orientation?
involves diagnosing and treating patients with brain injuries, neurological disorders, or psychological conditions.
what is classical neuropsychology’s methods?
Uses a variety of assessments, including neuropsychological tests, brain imaging (like MRI or CT scans), and clinical observations to understand how specific brain injuries impact overall functioning.
what is classical neuropsychology’s goal?
Aims to understand the broad effects of brain damage and to aid in the rehabilitation and treatment of individuals with brain-related impairments.
what is cognitive neuropsychology’s focus?
Concentrates on understanding the cognitive processes underlying behavior by studying individuals with brain damage.
what is cognitive neuropsychology’s research orientation?
More focused on theoretical aspects and how brain injuries can illuminate normal cognitive processes, such as memory, language, and perception.
what are cognitive neuropsychology’s methods?
Often involves detailed case studies and experimental tasks designed to pinpoint how specific brain lesions affect particular cognitive functions. Emphasizes the use of single-case studies to develop and test cognitive theories.
what is cognitive neuropsychology’s goal?
Aims to understand the normal functioning of cognitive processes by examining how they break down in cases of brain damage. Uses this information to refine models of normal cognitive functioning.
what are 6 types of brain damage?
- Cerebrovascular accident (CVA or stroke)
- Neurosurgery (split brain)
- Viral infections (HSE, HIV)
- Tumour (glioma)
- Head injury (traffic accidents, rugby)
- Neurodegenerative disease (Dementias/ Alzheimer type)
which hemisphere is most often dominant for language?
left
define: ischemia
lack of glucose & oxygen supply
define: haemorrhage
bleeding into brain tissue
what is dissociation in the context of dreaming?
taking a 3rd person perspective
what are the 2 types of stroke?
ischemic & haemorrhage
which type of stroke are easier to recover
haemorrhagic strokes - you can drain the blood to save some of the neurons but in ischaemic stokes the neurons just die
what will neuropsychologists test after a stroke?
- Intelligence
- Memory
- Visuospatial
- Executive functions
- Sensation
what is the pyramids and palm trees test for stroke patients?
tests semantic memory by getting patients to decide on which image is more closely related to another
give 2 examples of visuospatial testing for stroke patients
draw something from memory or copy an image
define: single dissociation
If a patient is impaired on a particular task (Task A), but relatively spared on another task
(Task B)
define: classical single dissociation
if a patient is impaired in task A but performs normally on task B -eg omitting just the vowels when writing word
define: strong single dissociation
If a patient is impaired on a particular task (Task A), but relatively spared on another task
(Task B)
what is the cognitive psychological theory related to single dissociations?
a difficulty in one domain, relative to an absence in difficulty in another domain can be used to infer the independence of these domains
what does someone who omits vowels exclusively after a stroke teach us about the brain?
the brain has separate neural resources for processing of written vowels relative to consonants
define: double dissociation
Double dissociation is derived from 2 (or more) single cases with complementary profiles - eg person 1 performs well on task a but not b and person 2 performs well on task b but not a
what characterises Broca’s aphasia?
people understand but can’t articulate language
what characterises Wernicke’s aphasia?
people struggle to find the right word (semnatic)
what is a limitation of single case studies?
Lesion needs to be assessed for each patient, and no guarantee that same anatomical lesions have same cognitive effect in different
patients
Therefore the cognitive profile of each patient needs to be assessed separately from other patients
One can not average observations from single studies because each patient may have a different cognitive lesion that we can not know from beforehand
what are studies grouped by syndrome good for?
Group by syndrome: useful for investigating neural correlates of a disease pathology (e.g. Alzheimer’s)
what are studies grouped by behaviour good for?
Can potentially identify multiple regions that are implicated in a behaviour
what are studies grouped by lesion location good for?
Useful for testing predictions derived from functional imaging
what are the 3 methods for looking at brain lesions?
- Transcranial Magnetic Stimulation (TMS)
- Transcranial Direct Current Stimulation (tDCS)
- Neuropsychology
