A 77-year-old man developed acute vertigo and unsteady gait. Neurological examination revealed spontaneous left-beating nystagmus in the primary position. He fell to the left when walking without support. Magnetic resonance imaging showed an acute infarction involving the right parieto-temporal lobe. Although the vertigo and unsteady gait are most often associated with vestibular disorders involving the infratentorial structures, those may occur in cerebral infarction of the parieto-temporal lobe.

Memory in the brain is organized into multiple memory systems that perform different memory functions and have different neurologic substrates. The medial temporal lobe and midline diencephalic structures are essential in the establishment of new declarative memories and these memory traces are finally stored in domain-specific regions of the cerebral cortex. Nondeclarative forms of memory including skill learning, priming, and classic conditioning do not involve conscious recollection and rely upon the cerebral cortex, basal ganglia, and cerebellum.

The focus of this review is the anatomy and physiology of higher cortical visual areas in macaque monkey, which are homologous to regions of the human visual cortex and numerous clinical syndromes resulting from damage to these areas. I review the functionally segregated visual information pathways involved in increasingly complex visual processing and discuss the underlying mechanisms of clinical characteristics. An understanding of these areas is important, as many of these patients will seek the attention of the neurologist, ophthalmologist, even psychiatrist, poorly defined complaints that may be difficult to specifically define

Visual Segmentation is an important function of our visual system as it eventually enables us to form correct representation of the outer world objects or events. We used fMRI in search for cortical activity related to the perception of visual scene segmented by contrast of three visual cues in human beings. The stimuli used were three kinds of flickering random dot checkerboard: defined by 1)texture orientation contrast 2)color contrast 3)motion direction contrast. Using these stimuli, 9 healthy subjects were functionally scanned with 1.5T MR machine while they fixated their eyes and passively viewed the stimuli presented. In experiment 1, these three conditions sequentially appeared from a flickering random dot field, while in experiment2 they appeared from a dark screen with fixation point in the center. Even though all three checkerboard conditions were the same in both experiments, the overall activation patterns were quite different. The extrastriate areas, especially V4, and Parietal lobe were activated cue-invariantly in the first experiment, while only V1 was activated cue-invariantly in the second experiment. To investigate the effect of the flickering random dot field, experiment3 was carried out with 4 of the ex-subjects and it showed activation of V1 and deactivation of extrastriate area including MT area for the flickering random dot field perception. As flickering effect might have removed the V1 activation in experiment1 while comparing checkerboard conditions with flickering random dot field condition, it can explain the absence of V1 activation in experiment1, still it cannot explain the absence of V4 activation or Parietal lobe activation in experiment2. As V1 has been localized for boundary perception and V4 for shape perception and parietal lobe for binding different visual attributes, activation of these areas can be interpreted as such. However, the differences in the results of experiment1 and experiment2 suggest that differences of the start line in perceptual flow can activate visual cortices differentially.

Two hemiplegic cerebral palsy patients were studied to investigate the cortical mechanisms underlying preserved somatosensory capacity, using functional MRI(fMRI). Tactile stimulation was performed by brushing of palm, during fMRI study. By the affected hand stimulation, contralateral primary somatosensory cortex was activated in patient 1 and cortical area anterior to the lesion site was activated in patient 2. We suggest that reorganization of the somatosensory cortex after brain injury can be induced by recruitment of undamaged areas adjacent to lesion site.

Background
In the brain, the dominant primary motor cortex (M1) has a greater hand representation area, shows more profusehorizontal connections, and shows a greater reduction in intracortical inhibition after hand exercise than does the non-dominant M1,suggesting a hemispheric asymmetry in M1 plasticity. Methods: We performed a transcranial magnetic stimulation (TMS) study toinvestigate the hemispheric asymmetry of paired associative stimulation (PAS)-induced M1 plasticity in 9 right-handed volunteers.Motor evoked potentials (MEPs) were measured in the abductor pollicis brevis (APB) muscles of both hands, and MEP recruitmentcurves were measured at different stimulation intensities, before and after PAS. Results: MEP recruitment curves were significantlyenhanced in the dominant, but not the non-dominant M1. Conclusions: These results demonstrate that the dominant M1 has greaterPAS-induced plasticity than does the non-dominant M1. This provides neurophysiological evidence for the asymmetricalperformance of motor tasks related to handedness.