Localisation of function

Primary visual centre in brain in visual cortex, in occipital lobe. Visual processing begins in retina, light enters + strikes photoreceptors. Nerve impulses from retina transmitted to brain via optic nerve. Some impulses from retina travel to areas of brain involved in circadian rhythms, majority terminate in thalamus - acts as relay station, passes info to visual cortex.

If VC spans both hemispheres, right hemisphere receives input from left side of visual field, while visual cortex in left hemisphere receives input from right side of visual field. 

Visual cortex - diff areas, w/ each of areas processing diff types visual info eg colour, shape/movement.

Concerned w/ hearing. Mostly in temporal lobes on both sides of brain, where auditory cortex is. Auditory pathways begin in cochlea in inner ear, sound waves converted to nerve impulses, travel via auditory nerve to auditory cortex in brain.

1st stop from cochlea to brain - brain stem. W/in brain stem, decoding occurs. Next stop in thalamus, acts as relay station + carries out further processing of auditory stimulus. Last stop - auditory cortex - sound recognised, may result in appropriate response.

Resonsible for gen of voluntary motor movements. Located in frontal lobe of brain along precentral gyrus. Both hemispheres have motor cortex, on one side of brain controlling muscles on opp side of body.

Diff parts of motor cortex exert control over diff parts of body. Regions arranged logically next to each other.

Detects sensory events arising from diff regions of body. In parietal love, along postcentral gyrus - area of cortex dedicated to processing of sensory info related to touch.

Using sensory info from skin, somatosensory cortext produces sensations of touch, pressure, pain + temp - localises them to specific body regions. Both hemispheres have them, cortex on one side of brain receiving sensory info from opp side of body.

Studies 8 patients after 'Tan', all similar language deficits, along w/ lesions in left frontal hemisphere. Patients w/ damage in these areas in right hemispehre didn't have same language problems, -> identifying existence of 'language centre' in posterior of frontal lobe in left hemisphere. Critical for speech production. 

Area of brain involved in understanding language - posterior of left temporal lobe. Couldn't understand language.

W proposed language involves separate motor + sensory regions in diff cortical regions. Motor in Broca's area close to are that controls mouth, tongue + vocal cords. Sensory in Wernicke's area close to regions of brain responsible for auditory + visual input. 

Input from M + S regions thought to be transferred to W area where recognised as language + associated w/ meaning. Neural loop known as arcuate fasciculus running b/ween B + W area/ One end B's area, other W's area.

Evidence for diff functions of B + W areas - discovery damage to diff areas results in diff types of aphasia - inability to understand/produce speech as result of brain damage. Expressive - imapired ability to produce language. Result of damage to B. Receptive - impaired ability to understand. Result as damage to W.

Communication may be more important than localisation - case where loss of ability to read -> damage in connection b/ween visual cortex + W area. Suggests complex behaviours built gradually as stimulus enters brain, moves through diff structures before response produced. Damage to connection in procces -> impairment resemble damage to localised brain region associated w/ specific function.

Individual diffs in language areas - Bravelier et al (1997) - large variability in individual patterns of activation across individuals. Observed activity in right temp lobe as well as left frontal, temporal + occipial. Also gender diffs.

Dronkers et al (2007) - re-examined preserved brains of two B patients. MRI found other areas could have also contributed to reduced speech ability.