Stereognosis (also known as haptic perception or tactile gnosis) is the ability to perceive and recognize the form of an object using cues from texture, size, spatial properties, and temperature.^[1] In humans, this sense, along with tactile spatial acuity, vibration perception, texture discrimination and proprioception, is mediated by the posterior column-medial lemniscus pathway of the central nervous system. Stereognosis tests determine whether or not the parietal lobe of the brain is intact.^[2] Typically, these tests involved having the patient identify common objects (e.g. keys, comb, safety pins) placed in their hand without any visual cues.^[3] Stereognosis is a higher cerebral associative cortical function.^[4]:71

Astereognosis is the failure to identify or recognize objects by palpation in the absence of visual or auditory information, even though tactile, proprioceptive, and thermal sensations may be unaffected.^[5] It may be caused by disease of the sensory cortex or posterior columns.^[6]:632 People suffering from Alzheimer's disease show a reduction in stereognosis.^[7] Astereognosis can be caused by damage to the posterior association areas of the parietal, temporal, or occipital lobes, or the postcentral gyrus of either hemisphere.^[5] For other types of dementia, stereognosis does not appear to decline.

  References

1. ^ Yekutiel, M., Jariwala, M., & Stretch, P. (1994). Sensory deficit in the hands of children with cerebral palsy: a new look at assessment and prevalence. Dev Med Child Neurol, 36:61-24.
2. ^ Silvestri: Saunders Comprehensive Review for the NCLEX-RN Exam
3. ^ Unsworth, C.A. (2007). Cognitive and Perceptual Dysfunction. In S.B. O'Sullivan & T.J. Schmitz (Eds.), Physical Rehabilitation, 5th ed. (pp. 1180-1181). Philadelphia: F.A. Davis Company.
4. ^ Blumenfield, Hal (2002). Neuroanatomy Through Clinical Cases. Sunderland, MA: Sinauer. ISBN 0-87893-060-4. 
5. ^ ^{a b} Mauguiere, F., Desmedt, J.E., & Courjon, J. (1983). Astereognosis and dissociated loss of frontal or parietal components of somatosensory evoked potentials in hemispheric lesions. Brain, 106:271-311.
6. ^ Bickley, Lynn; Szilagui, Peter (2007). Bates' Guide to Physical Examination and History Taking (9th ed.). Lippincott Williams & Wilkins. ISBN [[Special:BookSources/0-7818-6718-0|0-7818-6718-0]]. 
7. ^ F. J. Huff, J. T. Becker, S. H. Belle, R. D. Nebes, A. L. Holland, and F. Boller (1987). "Cognitive deficits and clinical diagnosis of Alzheimer's disease". Neurology 37 (1119): 1119–24. PMID 3601078. 

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