An introduction to the brain

A quick overview of the brain

Two Hemispheres

Four major lobes

Frontal Lobes: Reasoning and planning, emotions premotor areas for voluntary movements
Parietal Lobes: Perceptions and Motor areas, also language (written and spoken), memory, principal motor areas.
Occipital Lobes: Visual areas, object recognition.
Temporal Lobes: Sound, memories,

Cerebellum (Little Brain) coordination

Brain stem

Spinal cord

Numbers

Neocortex (new brain) has an area approx that of an a3 sheet of paper, but is folded to allow it to fit in the skull.
About $10^6$ neurons per square centimeter
About $10^{10}$ synapses per square centimeter

See Chudler[Chudler15:_brain_facts_figures] for more information

Note, Cerebellum innervates ipsilaterally whereas the cortex works contralaterally.

Sensory Motor cortex

Penfield's Homunculus shows a strong mapping from brain regions to the body, however sensory motor actions utilise many other regions of the brain, for example the cerebellum is clearly involved although it is still not clear how.

Visual cortex

	Area	function
LGN	Lateral geniculate nucleus	Connects optic nerve to VA
IT	Inferior temporal cortex	Object recognition
IPL	Inferior parietal lobule	Interpretation of facial emotions
SPL	Superior parietal lobule	Orientation (connected to hand)
MSP	Medial superior temporal area	Optic flow ?
VA	Visual area	object colour, shape etc

Flow of information

Retinal data, primarily from the fovea, travels down the optic nerve, through the optic chiasm to the Lateral geniculate nucleus. LGN transmits the information on to the primary visual area V1, and gets feedback from the visual cortex,

V2 and V2 seem to do an initial process of the visual data and then trasmit information on in two streams.

Ventral stream (what)

V1 V2 V4 V8 IT (this stream is heading towards the language areas of the brain)

Dorsal stream (where)

V1 V2 V3 V7 (this stream is heading to sensory motor areas of the brain).

References

[Chudler15:_brain_facts_figures] Eric Chudler, Brain Facts and Figures last checked Nov 2015