UNIT 1 - biological brain

how do scientists study the brain?

LESION - brain tissue is destroyed & researchers study the impact of functioning

STIMULATION- brain regions are stimulated electrically, chemically, or magnetically & researchers study the impact of functioning

EEG

electrodes placed on the scalp measure electrical activity in neurons.

MEG

a head coil records magnetic fields from the brain’s natural electrical currents.

CT

X-rays of the head generate images that may locate brain damage.

PET

tracks where a temporarily radioactive form of glucose goes while the brain of the person given it performs a given task.

MRI

people sit or lie down in a chamber that uses magnetic fields & radio waves to provide a map of brain structure.

fMRI

measures bloodflow to brain regions by comparing continuous MRI scans.

“symptoms of depression & anxiety correlate w/ increased activity in the right frontal lobe, a brain area associated w/ behavioral withdrawal & negative emotion.

( thibodeau et al. in 2006 )

EEG

“soldiers w/ PTSD, compared w/ those who don’t have PTSD, show stronger magnetic fields in the visual cortex when they view trauma-related images

( todd et al. in 2015 )

MEG

“children’s brain injuries, shown in CT scans, predict impairments in their intelligence & memory processing”

( konigs et al. in 2017 )

CT

“monkeys w/ an anxious temperament have brains that use more glucose in regions related to fear, memory, & expectations of reward & punishment

( fox et al. in 2015 )

PET

“people w/ a history of violence tend to have smaller frontal lobes, especially in regions that aid moral judgement & self-control

( glenn & raine in 2014 )

MRI

“years after surviving a near plane crash, passengers who viewed material related to their trauma showed greater activation in the brain’s fear, memory, & visual centers than when they watched footage related to the 9/11 terrorist attacks”

( palombo et al. in 2015 )

fMRI

what are the functions of a medulla?

at the base of the brainstem

controls heartbeat & breathing

what are the functions of the pons?

just above the medulla

controls sleep & helps coordinate movements

what are the functions of the reticular formation?

nerve network that travels through the brainstem into the thamalus

helps control arousel & filters incoming sensory stimuli

what are the functions of the thamalus?

at the top of the brainstem

relay station for incoming & outcoming sensory information (but not smell)

what are the functions of the cerebellum?

at the rear of the brainstem

processing sensory input, coordinating movement & balance, nonverbal learning & memory

which structures make up the limbic system?

hypothalamus, amygdala, hippocampus

what are the functions of the amygala?

2 lima-bean-sized neural clusters

linked to emotion, fear, & aggression

what does research suggest about the functions of the amygala?

one study showed math anxiety is associated w/ hyperactivity in the right amygdala ( young et al. in 2012 ).

another study linked criminal behavior w/ amygdala dysfunction ( boccardi et al. in 2011 , ermer et al. in 2012 ).

researchers found when people view angry & happy faces, only the angry ones increase activity in the amygdala. ( mende-siedlecki et al. in 2013 )

what are the functions of the hypothalamus?

below the thamalus

directs eating, drinking, body temperature

what does research suggest about the functions of the hypothamalus?

stimulating the reward centers of the hypothamalus will motivate a rat to cross an electrified grid, receiving painful electric shocks, to reach a bar that will give additional stimulation.

what are the functions of the hippocampus?

small structure w/ 2 “arms” that wrap around the thalamus

helps process for storage explicit (conscious) memories of facts & events

what does research suggest about the functions of the hippocampus?

humans who lose their hippocampus to surgery or injury also lose their ability to form new memories of facts & events. ( clark & maguire in 2016 )

those who survive a hippocampal brain tumor in childhood struggle to remember new info in adulthood. ( jayakar et al. in 2015 )

NFL players who experience 1 or more loss-of-consciousness concussions may later have a shrunken hippocampus & poor memory. ( strain et al. in 2015 )

what is the cerebral cortex?

the intricate fabric of interconnected neural cells covering the cerebral hemispheres

the body’s ultimate control & information-processing center

divided into 4 regions called lobes

what 4 lobes make up the cerebral cortex?

frontal lobe

parietal lobe

temporal lobe

occipital lobe

located in both right & left hemispheres

functions of the frontal lobes?

involved in speaking, motor movements, judgement & decision-making

functions of parietal lobes?

receives & processes sensory input for touch & body position

functions of the temporal lobes?

each lobe receives auditory info, primarily from opposite ear

functions of the occipital lobes?

each lobe receives visual info, primarily from opposite visual field

functions of the motor cortex?

controls voluntary movements

functions of the somatosensory cortex?

registers info from the skin senses & body movement

functions of the auditory cortex?

receives info from the ears

functions of the visual cortex?

receives info from the eyes

what are the association areas?

most of the brains cortex which integrates info involved in learning, remembering, thinking, & other higher-level functions.

attention is shifted, planning occurs.

not specifically devoted to motor or sensory cortex functions

research on association areas:

the prefrontal cortex in the forward part of the frontal lobes enables judgement, planning, & processing of new memories (de la vega et al. in 2016)

people with damaged frontal lobes may have high intelligence test scores & great cake-baking skills. yet they would not be able to plan ahead to begin baking a cake for a birthday party. (huey et al. in 2006)

& if they did begin to bake, they might forget the recipe. (macpherson et al. in 2016)

the case of phineas gage

a tamping iron accident damaged neural tracks in his frontal lobe. his frontal lobes could no longer filter emotional reactions from the limbic system.

what is the broca’s area?

language center located in the left frontal lobe

involved in expressive language

what is the wernicke’s area?

language center located in the left temporal lobe

involved in receptive language

how does our brain adjust to new experiences?

plasticity: the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.

example of plasticity: london taxi drivers

taxi driver trainees spend 2-4 years memorizing all of the routes through london.

increased size of the hippocampus is shown in this population.

the brain changes in response to experience.

(maguire et al. in 2000, 2006)

example of plasticity: young girl’s right hemisphere

most of the right hemisphere of a young girl’s brain has been removed due to chronic seizures threatening her life.

due to the cross-wiring of the brain, she shouldn’t have been able to move the left side of her body, yet her left hemisphere compensated by putting other areas to work.

what is neurogenesis?

although the brain often attempts self-repair by reorganizing existing tissue, it sometimes attends to fix itself through neurogenesis - producing new neurons.