Thoughts, Consciousness and Memory

8/18/2019 Thoughts, Consciousness and Memory

1/28

Thoughts,Consciousness and

Memory

Jorge de Vera

Referrence: Cerebral Cortex, Intellectual Functions ofBrain, earning and Memory, Cha!ter "#, $uyton and

Textboo& of Medical 'hysiology, ()th *dition


2/28

•*ach thought certainly in+ol+es simultaneous sigmany !ortions of the cerebral cortex, thalamus, system, and reticular formation of the brain stem


3/28

-*FI.ITI/. /F T%/0$%T I. T*RM1 /F .*02CTIVIT34HOLISTIC THEORY /F T%/0$%T1

•2 thought results from a 5!attern6 of stimulationmany !arts of the ner+ous system at the same t!robably in+ol+ing most im!ortantly the CEREBCORTEX, THALAMUS, LIMBIC SYSTEM, AND RETICULAR FORMATION OF THE BRAIN STE


4/28

-*FI.ITI/.:

•

Consciousness can !erha!s be described as ourcontinuing stream of a7areness of either oursurroundings or our se8uential thoughts


5/28

MEMORY

•

Memories are stored in the brain by changing thsensiti+ity of syna!tic transmission bet7een neua result of !re+ious neural acti+ity

• ne7 or facilitated !ath7ays are called MEMORYTRACES.

• LONG-TERM MEMORIES RESULT FROM CHANSYNAPTIC CONDUCTION IN LOWER BRAINCENTERS.


6/28

'ositi+e and .egati+e Memory951ensitiator 5%abituation6 of 1yna!tic Transmission

NEGATIVE

INHIBITION OFSYNAPTIC PATHWAY

HABITUATION

POSITIVE

FACILITATIONSYNAPTIC PATH

MEMORYSENSITIZATI


7/28

Classi!a"i#$ #% M&'#(i&s.

SHORT-TERM MEMORY -memories that last for seconds or at most minuteunless they are con+erted into longer;term memo

INTERMEDIATE LONG-TERM MEMORIES

; 7hich last for days to 7ee&s but then fade a7ayLONG-TERM MEMORY

; once stored, can be recalled u! to years or e+enlifetime later


8/28

•

C211IFI*- 2CC/R-I.$ T/ T%* T3'* /F I.F/RM2TI/.1T/R*-:

). DECLARATIVE MEMORY

;memory of an im!ortant ex!erience:

• memory of the surroundings

•memory of time relationshi!s

• memory of causes of the ex!erience

• memory of the meaning of the ex!erience

• memory of one


9/28

) 1&ill Memory-%(&*+&$"l ass#!ia"& i"/ '#"#( a!"i0i"i&s 1&(s#$2s 3#

4 all the s&ills de+elo! for hitting a tennis ball inc

automatic memories


10/28

SHORT-TERM MEMORY

T%*/RI*1:

CIRCUIT OF REVERBERATING NEURONS

Fi5. )6-7 - A (&0&(3&(a"i$5 !i(!+i"8N&+(#$ A &9!i"&s B a$ 0i!& 0&(sa.:;a$&l, ER,


11/28

INTERMEDIATE LONG-TERMMEMORY •

ast for many minutes or e+en 7ee&s• They 7ill e+entually be lost unless the memory traces are 2

enough to become more !ermanent= /.$;T*RM M*M/R3

• *x!eriments in !rimiti+e animals ha+e demonstrated that mof the intermediate long;term ty!e can result from :

(Tem!orary chemical changes

)Tem!orary !hysical changes

>Both

; in either the syna!se !resyna!tic terminals or the syna!se!ostsyna!tic membrane


12/28

IN THE PRESYNAPTICTERMINAL ORPOSTSYNAPTICNEURONALMEMBRANEMemories lasting from a fe7 minutes u! to >7ee&s in the large snail APLYSIA.

/ne terminal is from a sensory in!ut neuronand terminate directly on the surface of theneuron that is to be stimulated? this is calledthe SENSORY TERMINAL.

The other terminal is a presynaptic endingthat lies on the surface of the sensoryterminal, and it is called the FACILITATOR

TERMINAL. T@/ '2T%@231:

( %abituation

) Facilitation


13/28


14/28

L#$5-T&(' M&'#(

•

long;term memory is generally belie+ed to resulactual structural changes, instead of only chemichanges, at the syna!ses, and these enhance orsu!!ress signal conduction


15/28

S"(+!"+(al C/a$5&s O!!+( i$ S$a1s&s D+"/& D&0&l#1'&$" #% L#$5-T&(' M&'#(8

•

The structural changes 7ill not occur if a drug isthat bloc&s -.2 stimulation of !rotein re!licatio!resyna!tic neuron

• the structural ca!ability of syna!ses to transmit a!!ears to increase during establishment of trueterm memory traces


16/28

;the most im!ortant of the !hysical structural chathat occur are the follo7ing:

( Increase in +esicle release sites for secretion oftransmitter substance

) Increase in number of transmitter +esicles relea

> Increase in number of !resyna!tic terminals

A Changes in structures of the dendritic s!ines th!ermit transmission of stronger signal


17/28

CONSOLIDATION OF MEMORSHORT-TERM MEMORY

M+s" 3& CONSOLIDATED:acti+ated re!eatedly

initiate chemical, !hysical, andanatomical changes in the syna!ses

LONG-TERM TYPE OF MEMORY

" to ( minutes for MINIMAL CONSOLIDATION( hour or more for STRONG CONSOLIDATION

BLOC;S THE DYNAMIC FUNCTION OF THE BRAIN CAN PREVENTCONSOLIDATION.

BR2I.

C/.T01I/.

BR2I.C/.C011I/

.

$*.*R22.*1T%*1I2


18/28

C#$s#lia"i#$ M&'#(

•

C#$s#lia"i#$ #% M&'#(5consolidated6

• the short;term memory if acti+ated re!eatedly 7initiate !/&'i!al, 1/si!al, and a$a"#'i!al !/in the syna!ses that are res!onsible for the longty!e of memory

• Consolidation and the time re8uired for it to occ!robably be ex!lained by the !henomenon of(&/&a(sal #% "/& s/#("-"&(' '&'#(


19/28

REHEARSAL ENHANCES THE TRANSFERENCSHORT-TERM MEMORY INTO LONG-TERM MEMORY

•

Rehearsal of the same information again and again in theaccelerates and !otentiates the degree of transfer of shomemory into long;term memory and therefore accelerateenhances consolidation

• Therefore, o+er a !eriod of time, the im!ortant features osensory ex!erience become !rogressi+ely more and morthe memory stores This ex!lains 7hy a !erson can remesmall amounts of information studied in de!th far better large amounts of information studied only su!erDcially

• It also ex!lains 7hy a !erson 7ho is 7ide a7a&e can conmemories far better than a !erson 7ho is in a state of mfatigue


20/28

NEW MEMORIES ARE CODIFIED DUCONSOLIDATION

•

/ne of the most im!ortant features of consolidathat ne7 memories are codifed into diEerent clainformation

• The ne7 and old are com!ared for similarities andiEerences

•

store the information about these similarities andiEerences, rather than to store the ne7 informaun!rocessed


21/28

ROLE OF SPECIFIC PARTS OF THE BIN THE MEMORY PROCESS

Hi11#!a'1+s P(#'#"&s S"#(a5& #% M&'#(i&• The hi!!ocam!us is the most medial !ortion of t

tem!oral lobe cortex, 7here it folds Drst mediallyunderneath the brain and then u!7ard into the linside surface of the lateral +entricle


22/28


23/28

•

&'Y ARE T'E 'PPOCAMP SO MPORTANT 'E(PNG T'E )RAN TO STORE NE& MEMO

;hi!!ocam!i are among the most im!ortant out!u!ath7ays from the (&a( and 1+$is/'&$"of the limbic system

• 2mong these moti+ations is the dri+e in the brairemember those ex!eriences and thoughts that either !leasant or un!leasant

• THE DORSAL MEDIAL NUCLEI OF THE THALAma&ing the decision about 7hich of our thoughts


24/28

•

Retrograde A#nesia;Inability to recall Meories !ro the past

• the degree of amnesia for recent e+ents is li&emuch greater than for e+ents of the distant !ast

• distant memories ha+e been rehearsed so manthat the memory traces are dee!ly engrainelements of these memories are stored in 7idareas of the brain


25/28

•

hi!!ocam!al lesions G can cause anterograde anretrograde amnesias or can be both

• damage in some thalamic areas; retrograde amn7ithout causing signiDcant anterograde amnesia


26/28

HIPPOCAMPI ARE NOT IMPORTANT IN REFLEARNING

•

hi!!ocam!al lesions usually do not ha+e diHcultlearning !hysical s&ills that do not in+ol+e +erbaor symbolic ty!es of intelligence

• Can still !erform !hysical s&ills


27/28

•

T%2. 3/0 F/R I1T*.I.$


28/28

Documents

Thoughts, Consciousness and Memory