Lecture 2 Flashcards
Animal models pros and cons
Pros:
-provides info that cannot be obtained in any other way
-some procedures too invasive for humans
Cons:
-lack of generalisability to humans
Single cell readings
-invasive method
-measures responsiveness of a neuron to a given stimulus (action potentials per second)
—spikes per second (firing/spiking rate)
Brocas asphasia
A deficit in the ability to produce speech as a result of damage to Broca’s area
-damage causes difficulties in comprehending more complex grammar and speech production
Wernickes asphasia
Speech production deficit caused by damage to wernickes area
-damage produces meaningless speech and difficulty comprehending language
Stroke (ischemic)
Brain is deprived of blood
Hemorrhagic stroke
Rupturing of blood vessel
Traumatic brain injury
Damage to skull and brain from external forces
-penetrating head injury
—skull is perforated and meninges are torn
-closed head injury
—coup contre coup injuries
—axonal shearings
Trends of traumatic brain injury
-Leading cause of disability globally
-more common in babies and males
-for females, most common in reproductive years (due to domestic violence)
Concussions
Least severe category of head injuries
-for a long time, effects of consciousness have been minimised
-30% lead to post concussive syndrome (memory loss, nausea, etc)
-most severe in children
Other types of brain injuries
-tumors
-viral infections
-neurodegenerative diseases
The fractionation assumption
Damage to the brain can produce selective cognitive deficits
The transparency assumption
Lesions affect one or more components within pre-existing cognitive system
-but also do not result in a completely new cognitive system being created
The universality assumption
All cognitive systems are basically identical
Brain plasticity
Ability of brain to repair itself both at the neuron and cognitive level
-moving the function from one area of the brain to another
Transcranial magnetic stimulation
Neurons are activated both from internal source and an external source with the latter disrupting the former
Pros:
-effects are brief and reversible
-location of stimulated site can be moved or removed at will
Cons:
-restricted to sites that can be stimulated
-accidents of nature
EEG
Electrodes placed on scalp record electrical signals emitted by the brain
-electrodes record a series of positive and negative peaks
-event-related potentials
Pros:
-excellent temporal resolution
-non-invasive
Cons:
-poor spatial resolution
Positron emission tomography(PET)
Radioactive substance injected into bloodstream, and allows detection of blood flow to different areas of the brain as participant completes tasks
Cons:
-radioactive substance
-poor temporal resolution
Functional magnetic resonance imaging (fMRI)
Large magnets detects active brain areas on a given cognitive task
-oxygenated blood reacts differently in a magnetic field than deoxygenated
-measures concentration of oxygen in blood
Pros:
-good spatial resolution
Cons:
-slow and expensive
-poor temporal resolution
Magnetoencephalography (MEG)
Combines spatial resolution of MRI and temporal resolution of ERPs
-measures magnetic fields produced by electrical activity in the brain
Connectionest models
Herb rule: Cells that fire together wire together
-brain consists of en enormous amount of interconnected neurons
-models cognition as a network of simple units communicating with one another
