system, the main function of the occipital lobe is that of vision. retinal sensors send signals through the optic tract to the lateral geniculate nucleus. once the lateral geniculate nucleus receives the information it is sent down the primary visual cortex where it is organized and sent down one of two possible path ways; dorsal or ventral stream. the ventral stream is responsible for object representation and recognition and is also commonly known as the "what" stream. the dorsal stream is responsible for guiding our actions and recognizing where objects are in space, commonly known as the "where" or "how" stream. once in the information is organized and sent through the pathways it continues to the other areas of the brain responsible for visual processing. the most important function of the occipital lobe is vision. due to the positioning of this lobe at the back of the head it is not susceptible to much injury but any significant damage to the brain can cause a variety of damage to our visual perception system. common problems in the occipital lobe are field defects and scotomas, movement and colour discrimination, hallucinations, illusions, inability to recognize words and inability to recognize movement. a study was done in which patients suffered from a tumour on the occipital lobe and the results shows that the most frequent consequence was contralateral damage to the visual field. when damage occurs in the occipital lobe it is most common to see the effects on the opposite side of the brain. since the brain regions are so specialized in their functioning, damages done to specific areas of the brain can cause specific type of damage. damage to the left side of the brain can lead to language discrepancies, i.e. difficulty in properly identifying letters, numbers and words, inability to incorporate visual stimuli to comprehend multiple ways an object can be found. right side damage causes non-verbal problems, i.e. identifying geometric shapes, perception of figures and faces. in almost all regions of the brain left side damage leads to general language problems whereas right side damage leads to general perception and problem solving skills. damage to the cortex many studies of different disease and disorders that have symptoms of memory loss have provided reinforcing evidence to the study of the anatomy of the brain and which parts are more utilized in memory. frontotemporal lobar degeneration and memory frontotemporal lobar degeneration (ftld) is a common form of dementia due to the degeneration of the frontal and temporal lobes. studies have found significant decreases in the essential needs for proper functioning in these lobes. the autobiographical domain in memory is largely affected by this disease. in one study, ftld patients were interviewed and asked to describe a significant event from five different periods of their lives. using the interview and different methods of imaging, the experimenters hoped to find links between patterns of brain volume loss and performance in the interview. through image processing, patterns of significant reduced parenchymal volumes that encompass the frontal and temporal lobes were found. through comparison to a control group of patients it was found that parenchymal volumes increased during episodic recall, and decreased during semantic recall. the experimenters discussed that lifespan autobiographical episodic recall was largely damaged in ftld patients and semantic autobiographical memory seemed to be spared. parkinson's disease and memory parkinson's disease involves both damage to the basal ganglia and certain memory dysfunctions, suggesting that the basal ganglia are involved in specific types of memory. those who have this disease have problems with both their working memory and spatial memory. most people can instantly and easily use visual-spatial memory to remember locations and pictures, but a person with parkinson's disease would find this difficult. he or she would also have trouble encoding this visual and spatial information into long-term memory. this suggests that the basal ganglia work in both encoding and recalling spatial information. people with parkinson's disease display working memory impairment during sequence tasks and tasks involving events in time. they also have difficulty in knowing how to use their memory, such as when to change strategies or maintain a train of thought.