PSY 220 EXAM 2

distinctions in the PNS

somatic nervous system, autonomic nervous system

somatic nervous system

sensation and voluntary movement

autonomic nervous system

non-voluntary regulation of the body’s internal environment

sympathetic nervous system

fight or flight response (preparing body to fight/combat or runaway)

parasympathetic nervous system

rest and digest (helping you calm down)

horizontal

top and bottom half (hamburger bun)

sagittal

left and right half (hot dog bun)

coronal

front and back half (loaf of bread)

dorsal

towards the back (humans: top of head)

ventral

towards the belly (humans: bottom of head)

rostral

front of the head, towards the nose/beak

caudal

back of the head, towards the tail

superior

above

inferior

below

anterior

in front of

posterior

behind

lateral

towards outside

medial

towards middle

contralateral

opposite side

ipsilateral

staying on the same side

right hemisphere

controls left side of the body

left hemisphere

controls right side of the body

spinal cord

dorsal root ganglion, ventral root

dorsal root ganglion

carries sensory information to CNS (brain)

ventral root

carries motor information to muscles

hindbrain

medulla, pons, cerebellum

medulla

controls vital reflexes like breathing heart rate, coughing etc. (automatic)

pons

area where many neurons decussate (crossing) to the contralateral side (above medulla)

cerebellum

important for movement, balance, coordination timing (ex: alcohol can affect the cerebellum)

midbrain

tectum, tegmentum

tectum (roof of midbrain)

superior colliculus, inferior colliculus

superior colliculus

important for vision

inferior colliculus

important for hearing

tegmentum

substantia nigra, red nucleus

substantia nigra

has dopaminergic neurons important for movement, degenerates in Parkison’s disease

red nucleus

important for voluntary movement

forebrain

cerebral hemispheres, subcortical structures (below the cortex)

cerebral hemispheres

cerebral cortex: folded outer surfaces of the brain, gray matter, important for cognition

subcortical structures (below the cortex)

→ thalamus

→ hypothalamus

→ basal ganglia

→ limbic system

cross species comparison

humans have a higher degree of cortical folding

gyri

out-extending “bumps” of cortex (gyrus = 1)

sulci

in-extending “grooves” of cortex (sulcus = 1)

occipital lobe

→ most caudal lobe of the brain

→ important for vision

parietal lobe

→ somatosensation (touch)

* body sensation

→ important for attention

→ processing spatial information

temporal lobe

→ ventral most lobe of the brain

→ important for hearing

→ important for longterm memory

→ important for language comprehension

→ important for object recognition

frontal lobe

→ rostral most lobe of the brain

→ helps regulate emotion

→ important for short-term/working memory

→ regulates judgement/decision making/reasoning

* executive functioning

→ important for movement

→ important for language production (speaking)

longitudinal fissure

separates right and left cerebral hemispheres

central sulcus

separates frontal lobe from parietal lobe

sylvian lobe (lateral sulcus)

separates temporal lobe from frontal and parietal lobe

parieto-occipital sulcus

→ separates parietal lobe from occipital lobe

→ can only be seen from a medial view

precentral gyrus

→ in front of the central sulcus

→ in frontal lobe

→ primary motor cortex

→ controls voluntary movement

post-central gyrus

→ behind (immediately) the central sulcus

→ in parietal lobe

→ primary somatosensory cortex

→ processing touch/body sensation

receptive field

the region of the sensory surface that makes a cell fire

→ touch, the location on the body

→ vision, the locations on the retina

→ audition, the regions of the basilar membrane (in cochlea)

somatotopic map

composed of cells with receptive fields that respond to a specific part of body surface

motor map

disproportionate representation of parts of body with fine motor control

somatosensory map

disproportionate representation of parts of body with fine sensory inveration

thalamus

→ important for relaying sensory and motor information

* have many thalamic “nuclei” (clusters of cell bodies)

hypothalamus

→ helps maintain homeostasis (maintaining balance in the body)

→ communicates with pituitary gland (connected)

basal ganglia

→ wraps around thalamus

* caudate nucleus
* putamen
* globus pallidus

\*important for movement, implicit memory (memory not available to conscious awareness)

hippocampus

→ important for explicit memory

→ deep within temporal lobe

* memory that is available to conscious awareness

ex: trying to remember answer for exam

ventricles

→ fluid-filled spaces (hollow)

→ contain cerebrospinal fluid (CSF)

corpus callosum

→ large white matter tract that connects both cerebral hemispheres

single-cell recording

record neural activity directly

→ place a thin electrode in or near a neuron (invasive)

→ count the number of action potentials per second

→ determine which experimental manipulations change the neural response

→ provides excellent spatial and temporal resolution

\*usually used with non-human animals

\*Only use humans if really necessary (brain surgery)

structural brain imaging

→ visualize anatomical structure of the brain

ex: differences between white/gray matter

→ abnormal structures (tumors)

functional brain imaging

→ visualize active processes in the brain

ex: neural activity, blood flow

spatial resolution

refers to the amount of detail you can see in the image

structural imaging

amount of neuroanatomical detail you can see

functional imaging

precision with which you can localize activation to specific brain regions

temporal resolution

→ relevant for functional imaging (and single-cell recording)

→ refers to the precision with which you can localize brain activation to a specific point in time

poor temporal resolution

minutes

good temporal resilution

miliseconds

structural imaging methods

structural brain imaging allows us to assess

→ brain damage

→ brain size

→ brain characterizes in a living person

C(A)T: computed (axial) tomography (S)

→ basically an “x-ray absorption map”

→ different tissues absorb different amounts of x-ray radiation → look different on the image

→ poor spatial resolution (compared to MRI)

→ less expensive than MRI

→ more often used in clinical settings (than in research)

appears bright on a CT

high density material absorbs a lot of x-ray radiation

appears dark on a CT

low density material absorbs little x-ray radiation

CT safety issues

exposure to radiation (x-rays)

MRI: magnetic resonance imaging (s)

→ structural MRI is basically a “proton density map”

→ protons have magnetic properties that are measured by the MRI scanner

→ different tissues have different proton densities and look different on the map

→ good spatial resolution (compared with CT)

→ MRI scanner is basically a very strong magnet, is always on

→ about 3000x stronger than the field strengthen at the surface of the earth

MRI safety issues

→ no metal on/in body

* jewelry
* pace makers

→ no loose metal objects in the room

* (remember, the magnet is always on)

MRI over CT

→ does not involve radiation and so it is safer

→ provides better spatial resolution

→ provides better discrimination between white matter and gray matter

→ can be adapted to functional MRI

PET: positron emission tomography (f)

→ a PET image is basically a “blood flow map”

→ areas with more active neurons receive more oxygenated blood

→ poor spatial resolution (compared to fMRI)

→ worst temporal resolution of functional techniques (compared to fMRI and to EEG/ERP)

→ can be used to measure resting brain activity

→ can be used to measure brain activity associated with doing a specific task

→ can be used to measure levels of substance in the brain (neurotransmitters, proteins) that bind to radioactive tracers

how is the blood flow map created?

→ radioactive substance is injected into blood stream

→ substance travels to brain; radioactivity measured by detectors around the head

→ areas where there is more blood flow (areas of the brain that are more active) emit more radioactivity

PET: safety issues

→ exposure to radiation

→ invasive (radioactive substance is injected into the body)

fMRI: functional magnetic resonance imaging

→ colored areas = functional image

→ functional data overlaid on a structural MRI (black & white)

→ basically a “blood oxygenated level map”

→ more oxygenated blood in regions of increased neural activity

→ oxygenated blood has different magnetic properties than deoxygenated blood (measured by the MRI scanner)

→ the more oxygen in the blood in a given region the brighter (more colorful this region looks in an (analyzed) fMRI scan

* can be used to measure brain activity associated with doing a specific task (or resting state)
* best spatial resolution of all functional techniques (compared with PET)
* good temporal resolution (compared to PET)

fMRI safety issues

same as MRI (uses sam equipment)

yellow-red color map

usually corresponds to “activations”

blue color map

usually corresponds to “deactivations”

fMRI vs. PET

→ using PET, it takes several minutes to take one snapshot of a brain while it is doing a task

→ using fMRI, it only takes seconds to take a snapshot

→ this is why fMRI has better temporal resolution than PET

→ but there is a neuroimaging technique that has much better temporal resolution than fMRI

EEG: electroencephalography

→ the electrical activity of neurons produces charges in electrical fields

→ electrical potentials recorded by electrodes placed on scalp

→ provides a continuous recording of overall brain activity

→ predictable EEG signatures are associated with different behavioral states

ERP: event-related potentials

→ measures neural activity related to a particular event

* an event can be a sensory stimulus, movement, etc.

→ electrical potentials across the scalp are measured as EEG

→ ERP has the best temporal resolution of all of the neuroimaging techniques

* “snapshot” is being taken continuously
* millisecond precision

→ ERP has the worst spatial resolution of all of the neuroimaging techniques

encephalon

brain

EEG

continuous

ERP

average across similar “events"

inverse problems

difficult to determine which brain regions generated the electrical signal at the scalp picked up by EEG/ERPs

ERP vs. fMRI

→ ERP is good for figuring out the time course of cognitive events (when? how long? etc.)

→ fMRI is good for understanding where in the brain these cognitive events occur

spatial resolution

→ structural: MRI > CT

→ functional: fMRI > PET > ERP

temporal resolution

functional: ERP > fMRI > PET

TMS: transcranial magnetic stimulation

→ pulses of electromagnetic field from coil induce an electrical field in the brain

→ can either:

* excite the cortex (induce movement, sensation, etc.)
* or disturb its function (temporary lesion)

→ lesion method can implicate brain regions as playing role in mental function

→ repetitive TMS over left frontal regions can sometimes alleviate symptoms of depression

TMS safety issues

potential to induce a seizure, even in subjects without any predisposing illness

MRI

Interested in measuring the __cortical thickness__ of an individual

ERP

Interested in determining the __timecourse__ of attention