Lashley saw himself as offering no more than analogies, not theories, in his quest for the neural mechanism of the reduplicated engram in the cerebral cortex.
2. My opinion is that Lashley offered important conceptions beyond the well known equipotentiality and mass action that were propaedeutic to the development of neuropsychological theory. Here are some examples:
(i) Pattern of neural activity is more important than locus of the activity in the brain in understanding higher mental functions like memory. I believe that Lashley would still insist that locating the activity in, say, the left third frontal convolution of the left cerebral hemisphere does not reveal how the nervous system works, although the location of activity may prove to be important in the clinic. (see Lashley, 1929).
(ii) The memory trace can be laid down and reduplicated in the brain in one trial. The improvement in memory with practice does not necessarily mean that resistance at the synapse is repeatedly reduced (see Lashley, 1924).
(iii) The reverberatory circuit of Lorente de N can provide a mechanism for sustained activity in the brain after the stimulus has terminated (see Lashley, 1938).
(iv) Non-continuity in discrimination learning is the rule in mammalian species (see Lashley, 1942a).
(v) Sensory and motor equivalence are matters that deserve to be considered from a neural point of view. Lashley took up these matters in some detail in his 1942b paper reprinted in my book.
(vi) "Lashley's lesson," that neurons unexcited during learning may still show the effects of learning. A more complete litany of Lashley's conceptual contributions may be found in my earlier book on Lashley (Orbach, 1982, pp. 2-14) and in the book under review (chapter 8).
3. Now, how can I reply to Palm's charge that I do not understand Hebb's theory, lacking any bill of particulars? Palm writes that he read mostly between the lines. Does his opinion rest on my treatment of Hebb's views of attention and stimulus generalisation? (chapter 7); or what is referred to today as the Hebb synapse? (chapter 2); or Hebb's experientially assembled neural lattice? (chapter 5). Or am I guilty of an error of omission? I wish I could respond with good humour, but without a more specific enumeration of my alleged failures to comprehend, I have no way of knowing what Palm is talking about.
4. In paragraph 4 of his review, Palm wrote that Lashley's experiments "finally convinced him that the memory trace could not be localized in a particular connection between two neurons in a particular place." I believe that this is a caricature of Lashley's view. I am not aware that any respected neuropsychological theorist in Lashley's day would have entertained such a possibility in any mammalian species -- certainly not Hebb.
5. Palm's characterisation of experimentalists deserves a comment. He sees Lashley as an experimentalist who "never fully committed himself to a theory because he knows that it is all too easy to falsify it experimentally" (paragraph 3). On this matter, Palm is probably right. I suggested as much in my book on p. 56, when I wrote "Throughout his professional career, Lashley seemed to have had a horror of being proved wrong. Hence his cautious writing."
6. In contrast, Palm writes, "The real strength and courage of Hebb was not just to formulate his theory of cell assemblies, but to rest all of his psychology on the hypothesis that this is it, and nothing else is needed. This strong commitment to a theoretical hypothesis is the real reason theoreticians insist on naming Hebb synapses after him." (paragraph 5). This is an interesting suggestion. Hebb himself demanded specificity in his theory so that it could be falsified. And, with good humour, he suggested that it would eventually be found false; it is just a matter of time! Keep in mind what has happened to Watson's strongly committed view that behaviour theory requires but two terms, stimuli and responses, and to Hull's stimulus-response-reinforcement theory, to which he too was strongly committed.
Hebb, D. O. (1949) The Organization of Behavior. NY: Wiley.
Lashley, K.S. (1924) Studies of cerebral function in learning. VI. The theory that synaptic resistance is reduced by the passage of the nerve impulse. Psychol. Rev. 31, 369-375. In Orbach, Jack (1998) The Neuropsychological Theories of Lashley and Hebb. MD: University Press of America.
Lashley, K. S. (1929) Brain Mechanisms and Intelligence. Chicago: University of Chicago Press. Reprinted in Dover Ed. 1963, with Introduction by D. O. Hebb.
Lashley, K. S. (1938) Experimental analysis of instinctive behavior. Psychol. Rev. 45, 445-471.
Lashley, K. S. (1942a) An examination of the "continuity theory" as applied to discriminative learning. J. Gen. Psychol. 26, 241-265
Lashley, K. S. (1942b) The problem of cerebral organization in vision. Biol. Symp. 7, 301-322. In Orbach, Jack (1998) The Neuropsychological Theories of Lashley and Hebb. MD: University Press of America.
Orbach, Jack (1982) Neuropsychology After Lashley. NJ: Erlbaum.
Orbach, Jack (1998) The Neuropsychological Theories of Lashley and Hebb. MD: University Press of America.
Orbach, J. (1999) Precis of: The Neuropsychological Theories of Lashley and Hebb. PSYCOLOQUY 10(029) ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1999.volume.10/ psyc.99.10.029.lashley-hebb.1.orbach http://www.cogsci.soton.ac.uk/psyc-bin/newpsy?10.029
Palm, G. (2000) From Lashley to Hebb: the development of a biophysical theory of learning. PSYCOLOQUY (11)047 ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/2000.volume.11/ psyc.00.11.047.lashley-hebb.15.palm http://www.cogsci.soton.ac.uk/psyc-bin/newspy?11.047