PARIETAL LOBE

Parietal LobeLocated in the front of the occipital lobes

Involved in several functions including sense of touch, detecting movement in the environment, locating objects in space and experiencing one’s own body as it moves through space.

The left hemisphere: more prominent for right handers and is involved in structuring information to allow us to read and write, make calculations and produce language.

The right hemisphere: more prominent role for left handers and carries out images and understanding of spatial relationships.

Damage Damage to the parietal lobe can

lead to:

Gerstmann’s syndrome – right-left confusion, difficulty with writing (agraphia), difficulty with mathematics (acalculia)

Apraxia - inability to perform tasks or movements when asked, even though the request or command is understood, they are willing to perform the task, they are physically able and it had been learned

Sensory impairment

Agnosia – lack of visual-spatial organisation

DamageDamage can also result in hemispatial neglect.

Characterised by an inability to attend to people, objects, or one’s own body on the side opposite the damaged area.

Hemispatial neglect patients may eat from only one side of a plate, or dress one side of their body.

Case study: Two patients could not conjure visual images of buildings on the left side of their home town (regardless of the direction they imagined themselves facing). This visual neglect, therefore, existed even in their imagination.

In the parietal lobe… Primary area is the

somatosensory cortex.

Different sections of the somatosensory cortex receive information from different parts of the body.

One section registers sensations from the hand, another from the foot, an so forth.

Also involved in complex visual processing, particularly the back regions nearest to the occipital lobe

OCCIPTAL LOBE

The Occipital Lobe At the base of the cortex,

toward the back of the brain (‘occipital’ refers to the rear of the head).

Processes visual information from the eyes in the primary visual cortex.

The visual association cortex, also in the occipital lobe, is the part of the brain that helps identify and make sense of the visual information from the eyes.

DamageVisual Agnosia

Case study: A patient who had a tumor in his right occipital lobe could see objects perfectly well and even describe them in physical terms, but he could not identify them by sight alone.

E.g. when presented with a rose, the man turned it around and around and began to describe it as a ‘red inflorescence’’ of some type with a green tubular projection. Only when he held it under his nose did he recognise it as a rose.

Damage can also cause visual hallucinations, blindness, inability to see colour, motion, or orientation and synaesthesia.

SynaesthesiaA condition where different senses is blended.

Common form – grapheme-colour synaesthesia, where letters and numbers are perceived as having specific colours. (e.g. the number seven is yellow)

When individuals view letters or numbers, the colour-processing regions of the occipital cortex is activated.

TEMPORAL LOBE

In the Temporal Lobe…

The temporal lobe contains both the primary auditory cortex and the auditory association cortex.

Also contains Wernicke’s area

Damage to the primary auditory cortex leads to hearing losses

Damage to the auditory association cortex produces more complex deficits.

Damage to the left auditory association cortex causes severe language deficits.

People with such damage are no longer able to comprehend speech, presumably because they have lost the circuits of neurons that decode speech sounds.

They also lose the ability to produce meaningful speech; their speech becomes a jumble of words.

Damage to the right auditory association cortex does not seriously affect speech perception or production, but it does affect the ability to recognise non-speech sounds, including patterns of tones and rhythms.

The damage can also impair the ability to perceive the location of sounds in the environment. The right hemisphere is important in the perception of space. The contribution of the right temporal lobe to this function is to participate in perceiving the placement of sounds

Wernicke’s Area Left hemisphere

Involved in the understanding of written and spoken language.

Damage to Wernicke's Area (Wernicke's aphasia) can lead to a loss of ability to understand language. The person can speak clearly, but the words that are put together make no sense.