Lecture 5- Studying brain Flashcards
What are 3 examples of neurological diseases w/ descriptions?
-Stroke (motor/language impairments depending on damaged brain are)
-Alzheimer’s disease (brain degeneration in later stages, starts in medial temporal lobe)
-Parkinson’s disease (motor deficits, degeneration of neurons in midbrain in substantia nigra)
What are 3 famous cases of brain injury?
-Patient Leborgne “Tan”(damage to left frontal cortex after stroke, deficits in speech production),
-Phineas Gage
-Patient HM suffered w/ epilepsy and had hippocampus removed to treat, memory impairments in LT
What are examples of brain studying methods?
-Behavioural studies
-Neuroanatomy/histology
-Electrophysiology
-Imaging eg MRI,PET
-Computational models/brain based devices
How do we understand the brain using these methods?
Understanding of brain-behaviour relations requires combination of many different methodological approaches.
Describe the HM case study
Surgical resection of medial temporal lobe eg hippocampus to stop epileptic seizures
-Behavioural/cog analysis found that there were impairments to declarative (recall eg episodic/semantic) and spatial memory
-Other cog/memory functions were largely unaffected
How would you describe memory systems?
Memory is not unitary concept
What are examples of declarative (explicit) memory?
Facts/events within the medial temporal lobe
What are examples of the non-declarative (Implicit) memory
Procedural skills, Priming, conditioning, non-associative learning
What are experimentally induced lesions?
Selective destruction of specific brain sites (mechanical, electrolytic, neurotoxic)
What are some examples of how to experimentally induce lesions?
-Temp pharmacological manipulations via pre implanted microcannula to switch neurons/receptors on/off.
-Electrical/chemical stimulation of brain areas.
-Optogenics in which you manipulate brain neurons to become light sensitive to excite/inhibit
What do brain legion studies suggest?
Hippocampus is necessary for spatial and declarative memory.
What is neuronal tract tracing?
WATCH LECTURE VIDEO
What is the hippocampus connected to?
Hippocampus is connected to all sensory cortex eg visual which can help form memories
What is electrophysiology?
You plant electrodes into brain region to record specific electrical signals from neurons in this area.
This means you record electrical activity of brain though single unit and local field potentials
What are single unit recordings in electrophysiology?
Recording activity of single neurons
What are local field potentials in electrophysiology?
Recordings in which you record electrical potentials generated by many neurons (field potential)
Can be called brain waves/brain oscillations
When would you use single unit + LFP in humans?
Only conducted in rare cases for the pre-surgical evaluation of epilepsy patients (Engel et al., 2005).
What is surface EEG in humans?
Spontaneous and event-related (evoked), electrodes on surface of skull (weaker signals)
What is Magnetencephalography in humans?
Measures the small magnetic field changes accompanying electrical voltage changes due to brain activity. Better spatial resolution than EEG.
What are MRIs?
Images are generated from magnetic-resonance (MR) signal that emanates from hydrogen nuclei in brain tissue when these are aligned by a strong magnetic field and then excited by a magnetic pulse.
What are structural MRIs?
Non-invasive imaging of brain structure based on MRI contrast between different tissue types due to different densities of H nuclei. Confirms brain region damage.
What are functional MRIs?
Non-invasive imaging of brain ‘activity’ based on MR signal changes associated with metabolic and cerebral-blood-flow changes.
Most common method is based on changes in the Blood-Oxygen-Level-Dependent (BOLD) MR signal.
What are PET scans?
Positron Emission Tomography
Involves injection of radioactive tracers that resemble compounds of biological interest which can be followed into the brain to eg monitor metabolic activation
What are Parkinson’s changes?
Less DAT in striatum so reflects degeneration of dopaminergic fibres that express this transporter at terminals.
-More binding of dopamine receptor-specific tracer so reflects less dopamine release that could displace tracer from receptor.
-Some regions hypo-, others hyperactive; changes across disease course
