Many of the cognitive techniques that look at the brain from outside of the hippocampus have been criticized for there invasive nature, research techniques that require the introduction of an "instrument" into a subject's brain -- a scalpel, a probe, an electrode, a finger, are extremely invasive to a subject There are several methods of this sort. Surgery is the oldest. And an enormous amount of knowledge about the functional organization of brains has been gained through modern neurosurgery upon conscious patients, are another classic invasive neuroscientific method. Through observing the deficit that a lesion causes, then observing the brain (after autopsy) to localize the lesion, lesion studies have contributed a great deal to our present understanding of structure-function relations in the brain, they have also given us a great understanding of object recognition.
Hippocampal damage has been known to impair memory abilities and object recognition, but this is not the only explanation of recognition impairment, treatments that have been shown to cause disruption of hippocampal fuction, including ablation have failed to impair performance on object-recognition, a study by Aggleton et al. (1985) found that the hippocampus plays a very limited role in object recognition. We will now look at how brain injury effects and helps us understand object recognition, research suggests that focal brain lesions can disrupt the passive object recognition system ( Caramazza & Shelton, 1998) .In the last several years a number of new and exciting non-invasive techniques have become available for directly examining brain structure, and more recently brain function. , , and are some of the new techniques that allow the experimenter to take a look at the brain while it is awake this also means the brain is fully intact. Using a computer the experimenter can then construct a series of pictures of different regions of the brain. While CAT and MRI show what the brain looks like structurally PET, fMRI, and MEG show areas of the brain that are active or functioning, experimenters can look at areas involved in different cognitive activities, such as object recognition, this means that they can tell with some accuracy where in the brain activity is occurring, and what part of the brain we use for object recognition.
they can also measure different brain functions. All of these scans can look at the neuronal basis of reading and listening to language and we also use the technique to compare reading and listening to other cognitive skills such as listening to music and looking at pictures. This is where object recognition can be assessed the fMRI and PET scan can assess whether the same or very similar brain systems are involved in processing different kinds of information or objects and can also look at how the brain has evolved it’s different systems for dealing with different types of information and objects. In comparison to invasive techniques such as brain lesion studies it is much more ethical and more specific and advanced, the only problem researchers encounter is that the machines are extremely expensive and therefore it is difficult to get time to use them.
A study by Rossien et al. (2004) on the the human visual object recognition system which distinguishes between faces, objects, and words found when using Fmri /PET scans that the right hemisphere of the brain has an advantage in the early categorization of objects, and there is a strong left hemisphere bias forward like stimuli that does not seem to be related to language. This is a start to trying to understand object recognition through Fmri/PET scan, but there is a lot of work to be done in the area, the research area is relatively new. Further studies will have to clarify the respective role of the structural differences between the left and right hemispheres of the brain and also focus on the individual differences of people. Among brain imaging technologies, the best know and most widely used are Positron Emission Tomography (PET) and functional Magnetic Resonance Imaging (fMRI). Both technologies measure changes in cerebral blood flow that result from neural activity. Both allow cognitive neuroscientists to make images of these changes in normal human brains as subjects perform cognitive tasks. PET and fMRI have a spatial resolution in the millimetre range, but temporal resolution of at best seconds. These methods allow us to see how cognitive tasks change brain activity at the level of cortical columns to cortical maps, brain structures that contain millions of synapses. However, because these technologies have relatively poor temporal resolution, they can tell us little about the timing and sequencing of the component processes in a cognitive task. For example, consider skilled reading. Skilled readers fixate and process one word every 250 milliseconds, identifying the word, assigning it a meaning and grammatical role, integrating in into a grammatical structure, and incorporating it into a text model. Thus, these imaging techniques can help us localize areas of brain activity that underlie the cognitive components of reading, but they cannot tell us much about the temporal dynamics of those brain processes. In skilled reading, too much happens in one second. Brain recording techniques like electroencephalography (EEG), evoked response potentials (ERP), and magnetoencephalagraphy (MEG) measure the electric or magnetic fields that neural activity generates at the scalp surface. These methods have a temporal resolution in the millisecond range, but a spatial resolution of only centimetres. These techniques allow accurate timing of changes in brain activity during a cognitive task, but can localize that activity with a precision only in the range of tens to hundreds of millimetres, often only to the level of hemispheric regions. Thus, using cognitive models and analyses in imaging and recording experiments, cognitive neuroscientists can map elementary cognitive operations, occurring on a time scale between milliseconds and seconds, onto brain structures that range in size from hemispheric regions (centimetres) to cortical columns (millimetres).
Doniger et al. (2000) found that Object recognition is achieved even in circumstances when only partial information is available to the observer.
