how to study the brain

Question 1

what are the methods to study the brain

Answer 1

• behavioural studies
• manipulations of the brain
• neuroanatomy and histology - structural
• electrophysiology - listening to electrical activity neurons
• imaging - non-invasive
• computational models/brain-based devices

Question 2

what happened to patient H.M

Answer 2

• surgical resection of medial temporal lobe, mainly hippocampus, to stop epileptic seizures
• impairments in specific types of memory, including aspects of declarative and spatial memory
• other cognitive and memory functions were largely unaffected

Question 3

what are some experimentally induced lesions and other brain manipulations

Answer 3

• selective destruction of specific brain sites
• temporary pharmacological manipulations via pre-implanted micro-cannulae to switch neurons or specific receptors on and off
• electrical stimulation of specific brain sites
• targeted mutations of brain specific genes
• optogenetics - manipulate specific neurons so they become light sensitive - shining light either activates or inhibits neurons
• trans-cranial magnetic stimulation - induce magnetic field using coils - limited spatial resolution

Question 4

what is the watermaze for rats to study selective place learning deficits after hippocampal lesion

Answer 4

• animals have to find hidden thing using spatial cues - more often they experience location - the better the spatial memory gets

Question 5

what is the hippocampus necessary for

Answer 5

• spatial and declarative memory

Question 6

what is the neuroanatomical study of brain connectivity

Answer 6

neuronal tract tracing

Question 7

what is neuronal tract tracing

Answer 7

take compound called tract tracer - connect to one brain region and travels either direction of action potential or the opposite - look where the tracer is deposited

Question 8

what is diffusion magnetic resonance imaging

Answer 8

highlights white fibre tracks - human brains - less spatial

Question 9

what is the hippocampus connected to

Answer 9

all sensory cortex’s

Question 10

how is the electrical activity in the brain recorded

Answer 10

electrophysiology

Question 11

what are single unit recordings

Answer 11

• recording the electrical activity of single neurons

Question 12

what are local field potential recordings

Answer 12

recording electrical potentials generated by many neurons
- also known as brain waves - certain behaviour traits are categorised by different LFP - helps to discriminate between phases of sleep

Question 13

what is invasive single-unit and LFP recordings

Answer 13

• only conducted in rare cases for the pre-surgical evaluation of epilepsy patients - pinpoint where the seizures came from

Question 14

what is a surface EEG

Answer 14

• spontaneous and event-related - weakened and difficult to interpret

Question 15

what is Magnetencephalography MEG

Answer 15

• measure the small magnetic-field changes accompanying electrical voltage changes due to brain activity
• better spatial resolution than EEG
• requires big machine - very expensive

Question 16

what is an MRI

Answer 16

• images are generated from magnetic resonance 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

Question 17

what is structural MRI of the brain

Answer 17

non-invasive imaging of brain structure based on MRI contrast between different tissue types due to different densities of H nuclei

Question 18

what is functional MRI of the brain

Answer 18

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 MR signal

Question 19

what is positron emission tomography

Answer 19

• involves injection of radioactive tracers that resemble compounds of biological interest.
• using dedicated detectors around the head, these tracers can be followed in the brain

Question 20

what are the changes in parkinson’s shown in PET scans

Answer 20

• less DAT in striatum -n reflects degeneration of dopaminergic fibres that express this transporter at terminals
• more binding of dopamine receptor-specific tracer - reflects less dopamine release that could displace tracer from receptor
• some regions hypo-, others hyperactive, changes across disease course

Question 21

what are the modelling brain examples

Answer 21

• darwin X and it’s simulated brain
• spatial memory task
• spatial learning
• place-specific firing in simulated hippocampus