Organization and function of the cerebrum

cerebral cortex

thinking, memory, voluntary motor movements & sensory perception

grey matter

(somas of neurons) on outside

white matter

(axons of neurons that are myelinated with fat) on inside

Cerebral Deep Grey Matter

basal nuclei (ganglia)
limbic system

Spinal Cord

grey matter inside, white matter outside (to contact the muscles)

superficial grey matter (neurons)

Gyri = hills
Sulci = groves

Left hemisphere of brain

logic and reasoning (math, language etc)

right hemisphere of brain

creative brain, spacial orientation, object recognition

longitudinal fissure contains

falx cerebri, superior and inferior sagital sinus

primary motor cortex (pre central gyrus)

motor neurons can be found there

• send their axons through the cortex, brain stem and into the spinal cord to talk to muscle for movement

• mostly controls structures of the face and hands (homunculus man)

primary sensory cortex (post central gyrus)

sensations from the body (touch, pressure, position, pain, temp)

anterior

mostly motor

posterior

mostly sensory

frontal lobe

intelect, planning

parietal lobe

• somatosensory cortex

• association cortex (remember sensations)

• common integrative area (all senses put together: vission, taste, hearing smell to give you picture of your environment)

temporal lobe

• auditory cortex (hearing)

• association cortex (remember sounds)

• limbic system (regulates emotions and forms memories

occipital lobe

visual cortex (sight)
association cortex (remember sights)

frontal eye field (frontal lobe)

voluntary eye movement

Broca’s Area (frontal lobe)

speech (move mouth muscles to speak)

Wernicke’s Area (temporal lobe)

dictionary (responsible for deciphering language)

insular cortex (deep in the frontal, parietal and temporal lobe)

balance
emotional context to sensation (good pain, bad pain)

Olfaction (frontal lobe above eyeballs)

smell (what smell is it)

primary Gustatory Cortex

taste chemoreception and food preference

Commissural Fibers

between hemispheres

(e.g., corpus callosum,
anterior commissure)

Association Fibers

within hemispheres between lobes

• fornix

Projection Fibers

to distant parts of the CNS
(e.g., internal capsule) (cortex to spinal cord / vise versa)

Basal Nuclei

motor memory, initiate/stop movements, early motor learning, skills/habits

Basal Nuclei structures

• Caudate (head)

• lentiform nucleus (putamen and globus palliduc)

• caudate (tail)

Basal Nuclei related structures

substantia nigra of midbrain - dopamine

Huntington’s Chorea

Neurodegeneration in striatum = increased movement (no stop signal)

Parkinson’s

Lack of dopamine acting on the striatum = difficulties start / stopping movements (since dopamine is needed to carry info out of basal nuclei)

Information Pathway in Basal Nuclei

Premotor > BN > Thalamus > premotor

limbic system

emotions + memories

Hippocampus

who, what, when, why
• long-term memory formation
(consolidation)
• output via fornix

Fornix

connects hippo to mammillary bodies

Mammillary Bodies

olfactory relay nucleus (sensations for smell come through and get forwarded to other parts of the brain to be processed)
• emotion (good or bad ??)

Amygdala

• visual input from eyes (scanning for threats)

• will make a response if it is dangerous (fight/flight/freeze)

• emotional memories (good bad???)

• talks to hypothalamus

Pathway for Limbic system

1. info from hippocampus and amygdala is sent to the mamillary bodies via the fornix

2. information travels to the thalamus via the mammillothalamic tract.

3. From the thalamus the information is sent to the PFC and cingulate cortex (gyrus) via the anterior thalamic tract.

Hippocampal formation

• takes senses and makes it a memory (consolidation)

• info flows in and out of the entorhinal cortex

entorhinal cortex

internal map; your gps

prefrontal cortex

regulates attention / importance

Cingulate gyrus (reality checker)

major connecting hub between cerebral cortex and limbic system

• dysfunction can cause Schizophrenia

Episodic memory

1) Sensations (current or past)
cingulate cortex =
reality check
2) Sensations relayed to
hippocampus via EC
3) Hippocampus & EC impart
context (W’s)
4) Consolidated information
relayed to mammillary
bodies (emotion) via fornix
(inner arc)
5) Output to ant. thalamus,
then to cingulate cortex and
PFC (ant. thalamic tract)
6) If important – long term
storage in the cortex
(consolidation)

Amnesia

memory loss of facts or experiences

Anterograde amnesia

refers to a deficit in the ability to form new memories following the time of brain injury.

Retrograde amnesia

refers to a loss of long-term memories.

Declarative memory

memories you can recount (short term and long term)

• episodes (episodic) or facts (semantic)

short term memory (Declarative)

• thalamus

• amygdala

• hippocampus

long term memory (Declarative)

somatosensory, visual, cortexes etc.

procedural memories (muscle memory)

• cerebellum

• basal nuclei

Cerebellum

vision, balance, position (novel tasks)

basal nuclei stores

early experiences (ex. walking for the first time) (skills/habits)

Thalamus determines

whether to use the basal nuclei or cerebellum to preform a task