Participate in Cognitive Neuroscience Experiments for extra credit!

Midterm 1 Wednesday this week!

Review Session Today at 4 in this room

Cognitive Operations What does the brain actually do? Some possible answers:

First Principles “cognitive operations are processes that generate, elaborate upon, or manipulate representations” – As patterns of activity in one or more neurons – We often lack conscious access to these representations – Neuroscientists still know very little about how information is represented in the brain

Mental Representations Mental representations can start with sensory input and progress to more abstract forms – Local features such as colors, line orientation, brightness, motion are represented at low levels How might a neuron “represent” the presence of this line?

Mental Representations Mental representations can start with sensory input and progress to more abstract forms – Local features such as colors, line orientation, brightness, motion are represented at low levels A “labeled line” -Activity on this unit “means” that a line is present -Does the line actually have to be present?

Mental Representations Mental representations can start with sensory input and progress to more abstract forms – texture defined boundaries are representations arrived at by synthesizing the local texture features

Mental Representations Mental representations can be “embellished” - Kaniza Triangle is represented in a way that is quite different from the actual stimulus -the representation is embellished and extended

Mental Representations Mental Representations can be transformed – Rubin Vase, Necker Cube are examples of mental representations that are dynamic

Mental Representations Mental Representations can be transformed – Shepard & Metzlar (1971) mental rotation is an example of transforming a mental representation in a continuous process Mentally rotate the images to determine whether they are identical or mirror-reversed SAME MIRROR-REVERSED

Mental Representations Mental Representations can be transformed – Shepard & Metzlar (1971) mental rotation is an example of transforming a mental representation in a continuous process

Mental Representations Mental Representations can be transformed – Shepard & Metzlar (1971) mental rotation is an example of transforming a mental representation in a continuous process

Mental Representations Mental Representations can be transformed – Shepard & Metzlar (1971) mental rotation is an example of transforming a mental representation in a continuous process – The time it takes to respond is linearly determined by the number of degrees one has to rotate – Somehow the brain must perform a set of operations on these representations - where? how?

Mental Representations Mental Representations can be transformed into abstract information representations – Posner letter matching task – Are these letters from the same category (vowels or consonants) or are they different?

Mental Representations Mental Representations can be transformed into abstract information representations – Posner letter matching task – Are these letters from the same category (vowels or consonants) or are they different? – Are they physically the same or are they the same in an abstract way - they are in the same category? A AaAa AUAU SCSC ASAS SAME DIFFERENT

Mental Representations Mental Representations can be transformed into abstract information representations – Posner letter matching task – Participants are fastest when the response doesn’t require transforming the representation from a direct manifestation of the stimulus into something more abstract

Mental Representations Mental Representations can interfere – Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour

Mental Representations Mental Representations can interfere – Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour RED

Mental Representations Mental Representations can interfere – Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour BLUE

Mental Representations Mental Representations can interfere – Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour GREEN

Mental Representations Mental Representations can interfere – Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour RED

Mental Representations Mental Representations can interfere – Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour BLUE

Mental Representations Mental Representations can interfere – Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour GREEN

Mental Representations Mental Representations can interfere – Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour – The mental representation of the colour and the representation of the text are incongruent and interfere – one representation must be selected and the other suppressed – This is one conceptualization of attention

Mental Representations Representations in neural a neural code aren’t limited to sensory information Other examples: – Place cells in hippocampus represent location of an animal in a local coordinate system

Mental Representations Other examples: Motor Neurons represent plan for future action

Mental Representations The cognitive neuroscientists asks: – where are these representations formed? – What is the neural mechanism? What is the code for a representation? – What is the neural process by which representations are transformed?