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Temporal Lobe Lesions
The temporal lobe has many different functions such as the processing of auditory and visual information, memory, and emotional responses to stimuli. Based on these functions, important symptoms for temporal lobe damage have been identified. These are: the impairment of auditory, musical and visual processing, an impaired long-term memory and a change in an individual’s personality and sexual behaviour. . The main causes of temporal lobe damage are brain injury, tumours, strokes and epilepsy.

Disorders of Auditory and Music Perception
Impairments of auditory processing have been identified as a symptom of temporal lobe damage. Graham, Greenwood and Lecky, (1980) found that bilateral lesions to the primary auditory cortex resulted in cortical deafness where the individual could neither hear speech or any environmental sounds Lesions to each primary auditory cortex individually result in different auditory dysfunction. Fujii et al (1990) found that patients with a lesion to the right primary auditory cortex have an inability to recognise non-verbal environmental sounds such as animal cries and transportation noises. On the other hand, patients with lesions to the left primary auditory cortex have an inability to understand speech, also known as pure word deafness. These patients are unable to understand speech as they have an inability to discriminate between different speech sounds, although they still maintain the ability to read, write and speak. Pure word deafness occurs as a lesion in the left auditory cortex prevents auditory information reaching Wernicke's area, which has been found to be involved in the comprehension of speech.

Other auditory dysfunctions have been identified with temporal lobe lesions such as auditory hallucinations. . Verbal hallucinations have been reported in individuals’ with left temporal lobe damage. Verbal hallucinations may include voices giving commands, advice or simply saying sentences or words. Whereas some people may be aware of their hallucinations, others are not and will often respond to their verbal hallucinations. Non-verbal hallucinations have also been reported as, Penfield and Perot (1963) found that stimulation of the superior temporal gyrus in the right temporal lobe created musical hallucinations.

Temporal lobe lesions also impair an individual’s perception of music. Shankweiler (1966) found that lesions in the right temporal lobe result in an inability to discriminate between melodies. Right temporal lobe lesions also result in impairments in pitch and timbre perception.

Disorders of Visual Perception
The temporal lobe has been found to be crucial for visual perception. Research has found that lesions in the temporal lobe produce impairments in the visual recognition of stimuli. Individuals with lesions in the inferior temporal cortex, in an area called Fusiform face area (FFA), have impaired facial recognition, also called Prosopagnosia. Individuals with Prosopagnosia cannot even recognise the faces of their own family members. Patients with lesions in the inferior temporal cortex can also have visual agnosia and impaired colour recognition, in addition to impaired facial recognition. However, these types of agnosia usually occur separately.

Other visual dysfunctions have been identified with temporal lobe lesions. Lesions to the optic radiation in the temporal lobe can produce a deficit in the individuals’ visual field called Quadrantanopia. Quadrantanopia affects a quarter of the visual field and lesions to the optic radiation with result in a superior homonymous quadrantanopia, which is the loss of the same quarter of vision in both visual fields. Bilateral temporal lobe lesions also produce deficits in the visual field, as Kluver and Bucy (1937) found that after the removal of both temporal lobes in rhesus monkeys, a visual agnosia occurs and the monkeys can no longer recognise objects. Temporal lobe seizures can also affect an individuals’ visual perception with objects appearing larger (Macropsia)or smaller (Micropsia) then their normal size.

Impaired long-term memory
Impairment in the creation of new long-term memories is also a symptom of temporal lobe damage. The medial temporal region, particularly the hippocampus, has been found to be an important structure in the retention of current memories. Research has shown that bilateral damage to the medial temporal lobes including the amygdala and hippocampus result in profound anterograde amnesia (an inability to create new memories after the lesion has occurred) within the individual. Other memory deficits have also been found in individuals with temporal lobe damage. The recall of visual information such as faces and non-verbal information such as drawings are impaired in individuals with right temporal lesions. Whereas left temporal lesions impair the recall of verbal information.

Changes in personality and sexual behaviour
Temporal lobe lesions have also been found to affect an individuals’ personality. Personality characteristics such as increased paranoia and aggression, emphasis on trivial details, obsession with religion and egocentricity are more prevalent within patients with temporal lobe lesions. Bilateral lesions of the amygdala result in an individual developing Kluver-Bucy syndrome. Kluver-Bucy syndrome involves specific behaviour changes in the individual such as an inability to recognise familiar objects, increased sexual behaviour, a desire to examine objects orally and memory deficits. Davis (1992) found that feelings of fear and anxiety are increased if the amygdala is stimulated suggesting that damage to the amygdala could also influence the emotions of the individual. Not only can temporal lobe lesions influence personality characteristics but it has also been found that sexual behaviour can be influenced by temporal lobe damage. Miller et al, (1986) found that patients with temporal lobe damage report an increase in their sexual behaviour.