Categorisation in human brain Domina Petric, MD

Important brain areas for categorisation are: left fusiform gyrus left hippocampus

Important brain areas for categorisation Left fusiform gyrus is activated when humans categorise objects by comparing it to a prototype. Left fusiform gyrus is responsible for recognising abstract images. When humans compare things to particular examples of a category, there is an activation of the left hippocampus. Left hippocampus plays an important role for the storage or retrieval of memories.

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Hippocampus Wikipedia.org

Fusiform gyrus functions Fusiform gyrus forms part of the ventral stream and plays a role in differentiating between different categories of objects. A degree of lateralisation has been observed in fMRI studies: there is greater activity in lateral regions for objects with greater similarity there is increased medial activation for more dissimilar objects.  Tyler LK, Chiu S, Zhuang J et-al. Objects and categories: feature statistics and object processing in the ventral stream. J Cogn Neurosci. 2013;25 (10): 1723-35.

Fusiform gyrus functions The fusiform face area (FFA) located on the lateral aspect of the mid-fusiform gyrus is involved in the perception and recognition of faces including recognising one's own face. It appears that the FFA on its own is insufficient for facial recognition. A functioning network of face-sensitive regions, including the occipital face area, is required. A body-selective region in the fusiform gyrus located close to the FFA that responds selectively to human bodies has also been identified in fMRI studies.  Literature at the end of presentation.

Fusiform gyrus functions The visual word form area (VWFA) is located in the left lateral fusiform gyrus and contributes to the recognition of visual words and reading. fMRI studies have shown increased activation in the VWFA as subjects learned to read.

Categories reduce information load! Thinking in categories or pigeonholing helps our brain in bringing order into a constantly changing world and it reduces the information load. 

Two main strategies of thinking in categories are: exemplar strategy prototype strategy

Prototype strategy When someone wants to find out, whether a certain animal fits into the category of bird, he or she will at first apply the prototype strategy and compare it to an abstract general “bird”. This prototype has the defining features of the class, like a beak, feathers or the ability to fly.

Exemplar strategy When someone encounters outliers or exceptions like an emu or a penguin, this strategy may be of no use. Then humans apply the exemplar strategy and compare the animal to many different known examples of the category. This helps humans to find the right category, even for “distant relations”.

Literature http://neurosciencenews.com/categorization-hippocampus- fmri-4711/: Boris Suchan. An interplay of fusiform gyrus and hippocampus enables prototype- and exemplar-based category learning” by Robert K. Lech, Onur Güntürkün, and Boris Suchan in Behavioural Brain Research. www.hersenletsel-uitleg.nl Wikipedia.org https://radiopaedia.org/articles/fusiform-gyrus (Dr Yuranga Weerakkody, Daniel Loh et al.)

Literature Tyler LK, Chiu S, Zhuang J et-al. Objects and categories: feature statistics and object processing in the ventral stream. J Cogn Neurosci. 2013;25 (10): 1723-35. Kanwisher N, Yovel G. The fusiform face area: a cortical region specialized for the perception of faces. Philos. Trans. R. Soc. Lond., B, Biol. Sci. 2006;361 (1476): 2109-28. Lidaka T. Role of the fusiform gyrus and superior temporal sulcus in face perception and recognition: An empirical review. Japanese Psychological Research. 2014;56 (1): 33-45

Literature Ma Y, Han S. Functional dissociation of the left and right fusiform gyrus in self-face recognition. Hum Brain Mapp. 2012;33 (10): 2255-67.  Steeves JK, Culham JC, Duchaine BC et-al. The fusiform face area is not sufficient for face recognition: evidence from a patient with dense prosopagnosia and no occipital face area. Neuropsychologia. 2006;44 (4): 594-609. Dehaene S, Cohen L. The unique role of the visual word form area in reading. Trends Cogn. Sci. (Regul. Ed.). 2011;15 (6): 254-62.

Literature Rossion B, Caldara R, Seghier M et-al. A network of occipito- temporal face-sensitive areas besides the right middle fusiform gyrus is necessary for normal face processing. Brain. 2003;126 (11): 2381-95.  Peelen MV, Downing PE. Selectivity for the human body in the fusiform gyrus. J. Neurophysiol. 2004;93 (1): 603-8.  McCandliss B, Cohen L, Dehaene S. The visual word form area: expertise for reading in the fusiform gyrus. Trends in Cognitive Sciences. 2003;7 (7).