Memory.

Waikato Times, Volume XXIII, Issue 1920, 25 October 1884, Page 2 (Supplement)

Memory.

By Dn. 11. Wood Bkown

Tin m. is no subject of Natuio so interesting as ]isjcholog). Man, ever since his cieation, has been tiding to penetiate the mjsteiy uund, and aitei thousands oi jears the subject is just as obbuue as it Yias to the fust investigatoi . The physiologist alone has beeniewarded, the psychologist is still still striving to wiest from Nature this her most Hibtle seciet. Wg shall show how nicnioiy acts fiom a physical standpoint, also the theories advanced explanatory of tho action of the mind. Wo may say that mcnioiy is an attiibute of the mind, but it would be moie coiicct to say that thfy aie synonymous, and that thought and imagination are attributes of memoiy. Science has not been able to explain the causation of memoiy, but her votaries have done much towaid explaining physically the action of it. It must be lemembeied, that while the data are voluminous, and the number of neive fibers and cells estimated, the conclusions arrived at are in many cases hypothetical as regaids the action of memory. The metaphysician has done but little, the physiologist almost eveiythmg. The most succinct definition of memory I find is Hibot's. He says that "Memory is the retention of ceitain btates, their repioduction and their localisation m the past." We certainly cannot wish for a moie clear analysis. Physiologists have located the intellect in the giay matter of the brain, a thzn ciusfc one-tenth of an inch thick and composed of convolutions and sulci. It has been estimated that theie aro about 300 square inches of gray matter upon both hemispheies. This crust is suppoi ted by white matter which is a mass of nerve fibies, and makes by far the largest part of the biain. The gray matter is composed of cells and übres, which, according to Mr. Bam, number about one billion and five billions respectively. These cells and fibres are the factors of memory, and for distinctiveness at this time I will denominate them memory cells. An acquisition is a certain thing acquired or learned, and m a richly endowed and highly retentive mind of, say, two hundred,^ acquisitions, each gioupiug would require five thousand memory cells aiid twenty'fivo thousand fibres. It must be remembeied that the brain, besides having memory cells and thoir associated fibres, is also a

sort of battery to furnish power for movements of muscles, acts of energetic volition, and also of feeling. The causation of memory is just as mysterious as that of life. Memory exists, and that is the sum total. Lifo was brought into existence, cither from a fortuitous combination of oxygen, nitrogen, hydrogen, and carbon, making protoplasm, which becamo animated, or by a special divine »ct of cication. Scientists generally agree that all life must have antecedent life, which to my mind is the only proper solution of biology. The two most plausible theories which account for memory physically are the residuum and vibratory. According to the former theory, when an impression is received by a cell, a residuum is left, the lesulfc of a chemical change or decomposition of its protoplasm. When we look upon a pear, certain colls respond to the excitation of the impressions of contour, color, size, and Btem ; the result of this responding is a residuum. If these impiessions are leponted often enough, a permanent residuum is formed, and wo have a momoiy cell. Decomposition is the act of separating the constituents of a compound. These constituents would bo elementary bodies, but in the above cells the decomposition is said to leave a residuum, but no explanation is given as regards the action of the residuum after it is foimed. lamat a loss for any logical deduction whereby I can understand the action which goes on in the cell after it has been completely decomposed and a peimanent lesiduum has foimed, which under this theory I would call a memory cell. The residuum theory lends us to the time when the cell becomes pormanently changed, but does not enlighten us vpin its subsequent action. The vibratory theory explains^ tho physiological action of memory in a very satisfactory znsmnei If we look at the pear, certain cells vibrate from excitation, lesultant frein the impression. Wo do not have, in this instance, any decomposition or residuum, limply a \ibratory movement. The cell lemains the same, except tho molecular arlangoment. Wlvn the impiession ceases, tho colls cease to vibiate, and obtain a period of rest which is essential to memory. It will be noticed I that the vibiation of a cell is clear to the mind, ' because it acts in its enthety, rests, and \ibrates again to tho same impression ; each vibration fixes permanently its peculiar movement, and we have a coll which vibiates to no other impression, and the result is a memoiy cell. This is much better than tho residuum theory, which leaves a lesiduum after eveiy cell vibiation and e\ontually a permanent one. When an impiession is received upon the letina, tympanum, tongue, fingeis, or olfactory bulbs, it is conveyed by proper nerve filaments to cells in the gitiy matter of the brain. These cells vibiate fioni excitation, and undeigo a change, say that of molecular arrangement. If this impression is repeated often enough, the molecules aio peimancntly changed, and wo have memoiy cells and lemember the impression. If, on the other hand, tho impression is made but once, and then not violently, the cells assume their fii3t condition and we fOlf 01 get tho inrpiession, it passes from our mind. In this connection let me _ say that in the ti ue sense we do not see an object, heai a sound, feel a substance, smell an odor, or taste edibles ; we simply become conscious of the impression when they irritate to vibration the cells m the giay matter. These impressions cause dift'»ient cells to vibrate tho same to tho same excitations, which allows differentiation, and memoiy is the lesult. If diiVeient cells lesponded to tho samo impression, there would bo no permanency, consequently no cognition. Why do tho same cells übiate to tho same impiossion? Tho most plausible explanation is molecular change If we stiike a bar of steel upon tho end with a hanimei, wo can pioduce a magnet. The blow causes a change of molecules in the steel, and polarizes them. Whether the molecules of a cell aie simply changed, or polarized, is hard to determine, but that some change takes place by vibiation is evident from the fact that wo remember more easily where tho impression is leceived many times. If the molcculai theory is coirect, and every substance is composed of molecules, the whole body of cells in the giay matter would be no exception. Some men of learning say that the molecules of the body aie polarized in health, and when disarianged disease is the result. If this is tme, and neivous foice electricity, and the brain the batteiy, why not say that the change in a memoiy cell is molecular ? Why* does the same cell librate to the same impression? Foico or motion travels m the direction of tho least resistance. When an impression is carried along a nerve hbie, there is a ceitam amount of lesistance, and every impression weakens its power to lesist, and each succeeding impression travels along the fibre which is attuned to it and has the least lesistance. If the same impiession is cairied on the sameneivc fibre, it must nccessanly reach the same cell, which \ibiates accoiding to its molecular change, and wo become conscious of the impiessions. I would, in this connection, say that repeated impressions are not always necessaiy to produce a memory cell. A sudden violent excitation will cause a permanent change in a cell. We all have expeiienced sudden impressions which wo ha\e never forgotten, and never have felt but once. To remember is to recur almost instantly without exertion of will, to recollect is to recall by associations, to gather ideas step by step until tho impression sought is brought to mind. We recollect by association, by a group of cells vibrating which excites another and so on. Accoiding to Bain, theie are about one billion cells and five billion iibrcs. These fibres connect cells and consequently gioups. It will be leadily understood how this occuis, if wo bear in mind how we think; how one thought brings another iiito consciousness. Wo smell a rose, itfa odor excites certain cells ; tluough fibic connections other groups are excited to vibration, and we are conscious of events where the lose assumed a prominent pait. We see a face which lecallsthe name and peculiarities of the possessor. We see a house, and recollect the persons living therein. The house causes an impression which excites to vibiation a gioup of cells, which in turn brings other gioups into activity and we know the occupants. Most of our thought is through asso ciation, comparatively little that is instantaneous. In leinembeung, time and space are of little value, but they are essential to lecollection. When wo indulge in retrospection, memoiy carries us back weeks, months, and years. We cannot lecollect without time and space. The time is the piesent, space the period between the occurrence and the present moment. We have a conscious and organised memory. When we perform an act with a distinct end m view, it is the lesult of conscious memory. When a beginner is learning to play upon a piano, eveiy note is struck by the effort of the will, and therefore conscious. In setting our watch, we do it consciously ; we have found the correct time and our mmd is on the act, and we turn the hands carefully until our aim is accomplished. Theiefore eveiy act of will power is the result of conscious memoiy. Intensity and duration are indispensable to conscious memory. If one of these conditions be wanting, or any other unknown to us, then consciousness (a part of the whole) would disappear, and that which would remain of the fact is organized. Intensity is a degree of concentration which may vary, owing to the striving of our states of consciousness to supplant one another, and victory results either from the superiority of one or weakness of the other. Duration is the period between the impression and consciousnes of it. Ribot says it requires 01G to 014 of a second to hear ; 0 - 21 to 0 - 18 of a second to touch ; and 0 "20 to 0*22 of a second to see. This would indicate that the expression, " quick as thought," is a mere iiguie of speech. The acts of organized memory are performed unconsciously, involuntarily. The odor of food will sometimes cause an increased flow of saliva. When we were learning to walk, our steps weie taken with hesitancy and deliberation — consciously ; now we walk without knowing it, our conscious memory, through continual repetition, has become organized. If we meet an obstruction on the sidewalk, we uncousciously move to one side to avoid it. This is the result of experience. We know intuitively that, if we do not turn, we will run into the obstruction. Intuition and organized memoiy are to my mind synonymous. We raise food to our mouth without consciousness ; this is the result of habit. Habit is resultant fiom frequent repetitions, which produce organized memory. Upon reflection we will find that comparatively few of our acts are conscious. Consciousness is a narrow wicket through which we are connected with the outer world. I spoke of a group of cells always vibrating to the same impression, and another argument in favor of that statement is the weariness which ensues upon protracted vision, hearing, taste, etc. If different cells responded to the same impression, there would be no weariness. Cells do become tired and refuse to act. If we look upon one color continually it becomes blurred, one continual sound becomes indistinct, the odor from a flower is at first acute, aiterward less fragrant. This would indicate two things ; first, that the same .cells respond to the same impressions ; second, that memory cells must have rest. This rest is given by exercising different faculties and by Bleep. But oven in sleep this result is not always attained, for we often dream, and dreaming is cell activity during sleep. This is proved by the fact that we never dream of anything but past events. Physiologists have proved that during sleep the brain is pale from want of blood, but if the sleeper dreams it is a brighter red. This would indicate an activity of the brain during dreaming. One of the peculiarities of dreaming ia the extremely

brief period which is required, also it takeß no note of time or space. A drop of water has caused a dreamer to travel thousands of miles, to drown in a lake and to wake him up. A gentleman in this audience once dreamed " that he was walking through a street, and stopped boforo a hardwaro store m which were stoves arranged in tieis one above another; while looking at them they fell with a, terrific crash to the floor." Another student throwing a box down stairs caused this dream and awakened the dieamer at the same time. Dr. Carpenter relates the case of a clergyman who fell asleep in the pulpit, awaking with the idea that he had slept for moio than an hour ; but on reforiing to his hymn book, he found that his sleep had lasted through the singing of a single line.