Abnormal stereognosis and graphesthesia indicate a lesion in which brain region?

• A. Sensory cortex in parietal lobe
• B. Cerebellum
• C. Temporal lobe
• D. Occipital lobe

Answer: (A)

Abnormal stereognosis and graphesthesia show a failure to interpret tactile and proprioceptive input at the cortical level, meaning the brain’s somatosensory processing regions are affected. These functions rely on the parietal lobe’s sensory cortex and adjacent somatosensory association areas to integrate touch, texture, shape, and spatial information. When this area is damaged, a person can’t identify objects by touch or recognize shapes or numbers drawn on the skin, even though the primary touch signals may be intact. The cerebellum coordinates movement, so its damage causes ataxia rather than impaired tactile recognition. The temporal lobe is involved in memory and language, and the occipital lobe processes vision; lesions there produce different deficits unrelated to stereognosis or graphesthesia. Therefore, the pattern best fits a lesion in the sensory cortex of the parietal lobe.