exam 4 review.

• working memory:


  cognitive system with a limited capacity that is responsible for temporarily holding information available for processing
• working memory works with short term memory
• Maintenance:


  storage and rehearsal. Ie: cellphone number in mental storage before saving it in your phone
• Control: 


  elaboration. Ie: articulatory control for the rehearsal
• Representations:

  symbolic codes for information stored either permanently or transiently in neural networks
• operations:

  processes or computations performed on representations
• Verbal working memory

  verbal rehearsal
• visuospatial working memory


  maintenance of spatial location, shapes, and colors in short term memory
• Prefrontal cortex - pfc

  Jacobsen and Malmo's findings contributes to the concept of working memory, emphasizing PFC role in attention and resisting interference
• Jacobsen: 


  PFC's role in immediate memory by showing impaired performance in monkeys on delayed response task following PFC lesion
• Malmo:


  challenged Jacobsen, shows improved performance in dark suggesting PFC lesions affect the use of short term memory amid competing stimuli
• ODR - oculomotor delayed response task


  remembering location of a visual stimulus and meeting a saccade to that location after delay
• ODR task conclusion: 


  • neuron in monkey PFC exhibits increased firing
  • Indicates neurons' role in spatial working memory showing specialization for holding spatial info
• Spatial working memory: 


  DLPFC involved in where and tracking location of object
• Object working memory

  ventral PFC involved in "what". Handling object identity like color and form.
• Macaque studies


  effect of lesion: decline in working memory performance in those with DLPFC lesions

  conclusion: neural activity in the DLPFC is crucial for memory-guided saccades
• Working memory - two hypotheses following Macaque studies

  1. lesions to human DLPFC will impair spatial working memory, affecting tasks like memory-guided task
  2. lesions to human principal sulcus will impair spatial working memory
• Working memory - human studies

  damages and disturbances to PCS will significantly affect spatial working memory

  • lesions led to memory error. increased for saccades to the visual field opposite lesion
• Basic Processing Unit:

  • Each neuron functions by receiving inputs (IN), which are then weighted (WE) by their respective importance or strength. The inputs are multiplied by these weights and summed up to form a total weighted input (Σg).
  • This sum is then passed through an activation function (AF), which determines the neuron's output based on the summed input.
  • The activation function decides how to transform the input into an output, like a threshold that needs to be crossed for the neuron to activate.
  • The output of each neuron can serve as an input to the neurons in the following layer
• Feed-forward neural network:

  • neurons pass data sequentially - no feedback loops
  • final output is the vector
• Recurrent neural network:

  • share feedback loops, recognizing sequential dependencies with intrinsic memory
  • constantly updating and adapting
  • Fire together = wire together, same time of activation = strengthened connection
• PANN

  • no oscillating point attractions
  • used for associative memory
• CANN

  • stabilized
  • multilayers
  • works as short term memory
• Bistability: when a neuron can either be excitatory or inhibitory based on inputs
• you need a good balance of excitation and inhibition to achieve stable states
• Cognitive Control:


  ability to focus on information that is currently relevant to a particular goal while inhibiting information that isn't relevant
• Cognitive control is dependent on...

  working memory, Inhibition and conflict monitering
• the proposed functions of cognitive control are...

  • attention
  • active maintenance
  • task switching
  • strategic retrieval
  • inhibition
  • performance monitering
• Phineas gage: 


  Man who survived a metal bar through his skull mainly damaging his PFC. His attitude and social control changes
• Inhibition tasks: 


  anti-saccade, go/no-go, countermanding, flanker, and stroop
• anti-saccade: inhibiting a reflex to look at a target and instead look away
• Go/no-go:

  involves responding to frequent stimulus and then inhibition response to rare stimulus
• Countermanding:

  measures ability to inhibit a preplanned action after a stop signal
• Flanker:

  stimulus in the center is flanked by either same or different symbol causes the task to be incongruent or congruent
• stroop:

  naming the color of the word or reading the word itself (naming the color of the word is harder)
• Neural recordings during inhibition: 

  • Fef activity is involved but not necessary in express saccades 
  • FEF activity is recorded during antisaccades aiding in the suppression of reflexive saccades 
  • Frontal lobe lesions hinder the ability to suppress automatic saccades
• Performance and conflict monitoring 

  SEF - pre saccade 

  • Conflict and performance monitoring and error detection
• Performance and conflict monitoring:

   DLPFC - task rule and task preparation 

  • Attention, inhibition and performance monitoring
• Performance and conflict monitoring:

  ACC - conflict monitoring 

  • Specifically active during the stroop tasks during incongruent trails – highest activity measuring when incongruent follows incongruent stimulus
• Race model: 


  Threshold that needs be crossed in order for action or saccade or decision to be inhibited or executed