Ethe size of brain organs is manifested in the external configuration of the skull

Phrenology (phren, Greek for 'mind',-logos, 'reasoning') was born toward the end of the eighteenth century. It is considered pseudoscience because of postulate e above. This postulate is 'craniometry'—the belief that one can determine a mental profile from the shape of the skull. The point is that while craniometry is indeed a preposterous claim, the rest of phrenology's assumptions do deserve proper attention. These are the modularity of mind (a above), the localization of function in the brain (b), the individual variability in innately predisposed potential (c), and the dependence of function on neural space (d). All these postulates are echoed in contemporary neuroscience. Assumption a, with or without the rest but in the absence of e, is 'neophrenology'. Many neuroscientists speak 'neophrenologish' without even being aware of it.

The founder of phrenology was the prominent neu-roanatomist Gall (Germany 1758-France 1828; Temkin 1947). Gall himself was not happy with the term 'phrenology', which was introduced by his co-worker, Spurzheim. But Gall never came up with a catchy term as an alternative. He developed his views of brain and mental function against the background of a variety of earlier theories. Quite a number of these theories considered mental function to be subserved by fluids (humours), in amazing disrespect to the tissue of the brain itself. Many also regarded the mind a unitary whole, unresponsive to physical dissection. Gall considered the available data, added his own observations, and spiced it all with the influence of the contemporary practice of 'physiognomy', the art of judging character and disposition from the features of face and body. Phrenology was the outcome. Gall's ideas arouse opposition among some and enthusiasm among others.

An example of the first was the decisive response by Emperor Francis I, who banished Gall from Vienna: 'This doctrine concerning the head, which is taken about with enthusiasm will perhaps cause a few to lose their heads and it leads also to materialism, therefore is opposed to the first principles of morals and religion' (cited in Greenblatt 1995). An epitome of the more enthusiastic reaction was provided, years later, by the poet Walt Whitman, who, swept by admiration for the new science, subjected his own 'splendid head' (sic.) to the test of phrenology (Davies 1971).

Phrenology as it became known in the nineteenth century was mostly Spurzheim's modification of Gall's conceptual framework. Gall originally distinguished 27 faculties. These included, among others, multiple memory systems ("taxonomy): memory for facts, memory for persons, and memory for words (Temkin 1947). Some ofGalls' proposed faculties pointed to unflattering facets of human nature: the instinct of killing, the desire to possess, pride, and vanity. Spurzheim, while expanding the list of faculties, got rid of the more annoying traits. He also emphasized the ability to improve 'deficient' faculties by training.

We will get a better appreciation of phrenology if we evaluate its premises in the context of present knowledge:

1. The modularity of mind. The basic assumption here is that the mind is a collection of different kinds of mental faculties. This view is also known as 'faculty psychology' (Fodor 1983). In principle, a 'module' may refer to a general type of mental function such as "attention, "perception, or memory, irrespective of the specific mental content or behavioural task. It could alternatively refer to a specific behavioural programme, e.g. "imprinting, or a specific mental "skill, e.g. language, musicality, or sociability, each of which requires attention, perception, memory, etc. The original phrenological maps listed mostly specific aptitudes rather than general mental processes that cut across skills (Temkin 1947). This view is shared by modern versions of the modularity of mind (Rozin 1976; Fodor 1983; Gardner 1993). The mere existence of mental modules could make sense from the point of view of the evolution, as different phylogenetic pressures might had advanced distinct mental capacities, to offer specific solutions to specific survival needs. It has furthermore been suggested that the progress in evolution toward more intelligent organisms involves enhanced interaction among different modules (Rozin 1976; see also 'central systems' in Fodor 1983). Neuropsychologi-cal analysis of brain-damaged patients with highly circumscribed behavioural deficits has been used as evidence for the existence of highly specific cognitive modules (Damasio 1990; Baynes et al. 1998). However, the relevance of the breakdown unveiled by pathology to the normal divisions of the mind, as well as its relevance to the modules/central processors distinction, awaits clarification. Another central question is to what degree are different modules innate (Karmiloff-Smith 1994; Spelke 1994; Markson and Bloom 1997; Paterson et al. 1999).

2. The localization of function. Whereas the modularity of mind supposes mental organs, the localization of function in brain assumes neural organs. The latter assumption is 'organology'. Note that modularity of mind does not entail organology. It is legitimate to assume mental modules while displaying complete indifference to their physical substrates. It is also possible to envisage a model in which the whole brain is induced, either spontaneously or by external "stimuli, to produce distinct mental modules at need. However, given the modularity of mind, some organology becomes a logical possibility. Phrenology prompted systematic attempts to localize brain function, including "engrams, by relying on the effect of disease and injury (Brazier 1988; Finger 1994; "method). We are now experiencing a new wave of this search, this time using "functional neuroimaging. The pitfall that the 'new organologists' (Marshall 1980) must avoid is the tendency to adhere to the descriptive levels,

Fig. 55 A phrenological map, delineating the location of 'mental organs'. Multiple versions of such maps have been issued throughout the nineteenth century. They usually depicted memory not as a unitary faculty but as multiple "systems (e.g. memory for words, memory for facts, memory for persons), or as an implied component of other faculties (e.g. language). (Reproduced from Davies 1971.)

Fig. 55 A phrenological map, delineating the location of 'mental organs'. Multiple versions of such maps have been issued throughout the nineteenth century. They usually depicted memory not as a unitary faculty but as multiple "systems (e.g. memory for words, memory for facts, memory for persons), or as an implied component of other faculties (e.g. language). (Reproduced from Davies 1971.)

rather than create a "model that will account for what the different organs and circuits compute and represent. Also, much as the localization of function is an attempt to dissect the brain into parts, it should not be forgotten that in situ these parts function together. The brain is not an homogeneous porridge, but also not a random collection of individual organs.

3. Individual variability in the innate potential. Genes influence human behaviour (e.g. McClearn et al. 1997; "a priori, "neurogenetics). But each distinct behavioural trait depends on many genes, most of which are pleiotropic (i.e. contribute to more than one phenotype). We also know that the structure and function of cognitive modules depend much on how the brain interacts with the environment (Sadato et al. 1996; Paterson et al. 1999; "development). Our current view on how much is nature and how much nurture depends on which trait is analysed and how one construes the data (Rose 1995a; Gelernter et al 1997; Leboyer et al. 1998; Noble et al. 1998; Flint 1999).

4. The dependence of function on neural space. The idea that brain space is correlated with "performance is not considered far-fetched any more (e.g. "birdsong). Consider, for example, the recent report that professional taxi drivers, who earn their living from navigation in urban streets, have a larger "hippocampus, a brain area critical for spatial memory (Maguire et al. 2000). But of course, nobody claims that such an alteration creates bumps on the skull.

5. Craniometry. Neither the shape of the skull, nor the overall size of the healthy brain, are indicative of mental power (Gould 1981). Gall himself objected to being called a craniologist, claiming that the focus of his research is the brain, not the skull. Therefore, despite the failure of his mental diagnostic methods, he would have probably been proud of neophrenology.

Selected associations: Engram, Homo sapiens, Red herring, Zeitgeist

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