The Lesioned Brain and Stimulated Brain
This chapter outlines various experimental approaches to manipulating the human brain, which includes damaging selective parts of the brain (“experiments of nature” such as caused by stroke) or stimulating the brain non-invasively (NIBS, non-invasive brain stimulation). Cognitive neuropsychology is concerned with inferring the structure of cognition from brain lesions (e.g., double dissociations) and in determining structure-function relationships (e.g., what a given region of the brain might be specialized for). The prominent NIBS techniques of transcranial magnetic stimulation (TMS) and transcranial electric stimulation (tES) are introduced from the perspective of a “virtual lesion.” TMS works by virtue of the principle of electromagnetic induction. TMS causes neurons underneath the stimulation site to be activated. If these neurons are involved in performing a critical cognitive function, then stimulating them artificially will disrupt that function. These methods can be adapted to improve as well as disrupt cognition.
Multiple Choice Questions
Flashcards
In neuropsychology, the performance of different patients is combined to yield a group average
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In cognitive neuropsychology, an approach where the data from different patients are not combined
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A name for a variety of methods that stimulate the brain non-invasively (i.e. outside the skull) including by magnetic, electrical and ultrasound methods
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Non-invasive brain stimulation (NIBS)
Non-invasive stimulation of the brain caused by magnetic induction from a rapidly changing electrical current in a coil held over the scalp
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Transcranial magnetic stimulation (TMS)
Non-invasive stimulation of the brain caused by passing a weak electrical current through it, either direct currents (tDCS) or alternating currents (tACS)
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Transcranial electrical stimulation (tES)
A surgical procedure in which fibers of the corpus callosum are severed
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Disruption in the blood supply to the brain; also called cerebrovascular accidents (CVA)
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Over-elastic region of artery that is prone to rupture
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A situation in which a patient is impaired on a particular task (task A) but relatively spared on another task (task B)
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If two tasks share the same neural/cognitive resource but one task uses it more, then damage to this resource will affect one task more than the other
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One task is performed worse than another because the task is performed sub-optimally (but not because some aspect of the task is compromised)
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Two single dissociations that have a complementary profile of abilities
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Difficulties in spelling and writing
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A cluster of different symptoms that are believed to be related in some meaningful way
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Lesions affect one or more components within the pre-existing cognitive system but do not result in a completely new cognitive system being created
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A swelling of the brain following injury
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A discrete brain lesion can disrupt the functioning of distant brain regions that are structurally intact
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Cognitive neuroscience in nonhuman animals
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Non-invasive stimulation of the brain caused by passing a weak electrical direct current through it
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Transcranial Direct Current Stimulation (tDCS)
Non-invasive stimulation of the brain caused by passing a weak electrical alternating current through it; the frequency of the alternations can interact with the brain’s own rhythmical activity
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Transcranial Alternating Current Stimulation (tACS)
Non-invasive stimulation of the brain caused by passing a weak electrical current through it, which fluctuates in direction and amplitude
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Transcranial Direct Current Stimulation (tRNS)
A form of tES that decreases cortical excitability and decreases performance
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Useful Links
International Neuropsychological Society: www.the-ins.org/
Jobs, news, and conferences linked to non-invasive brain stimulation: www.neuromodec.com/
Legal and ethical frameworks for animal research: www.nc3rs.org.uk/the-3rs www.grants.nih.gov/grants/olaw/tutorial/intro.htm www.eara.eu/en/animal-research/eu-animal-research-law-directive-2010-63/
