Chapter 10 - The acting brain

What are the components are involve in planning an action

visual analysis, object recognition, semantic knowledge, goals, plans and intentions, object based actions, sensory motor transformation, somatosensation, stored action, scrips and schemas, translation into a specific movement (like direction, force, speed, effectors etc.), motor output and feedback mechanisms (from propriosensation).

In the case of baseball → perceive body and bat (somatosensation - propriosensation)→ see the ball (visual analysis)→ ID that it is a ball (object recognition) and note its location (i.e. semantic knowledge), hit the ball (goals. plans and intentions from stored action scripts and schemas), ball with body, bat with hands and use a sensory motor transformation and then translate into a specific movement to create movement of arms and body to execute a motor output.

Action

culmination of all these sensory perceptual and motor information that collectively yielded a cognitive function that is action - action requires cognition

perceptual processes

things like touch, pain, limb position etc. that inform the brain about the body and environment, facilitating interaction and response.

somatosensation

perceptual processes that relate to the body

degrees of freedom (problem)

related to the number of possible ways to execute a desired action and move body in response to stimuli - the DOF problem states that there are technically infinite number of probable ways of performing an action such as turning on a light switch, however there are cognitive and physical restraints which limit the number of options that are available.

Somatosensation

perception of skin, body, touch, pain, temp, etc. - sensing of the body

proprioception

information about limbs and body position in space.

sensorimotor transformation

combining senses about body placement with the motor program to act → knowing cognitivly where an object is in space and knowing the position of the body (via propriosensation) relative to the object. (remapping)

Homonculus

little man serves as our bodies awareness and representation

Frontal eye field (Brodmanns area no. 8)

determines voluntary movement of eyes - controlled and guided by external perception of visual and auditory stimuli (not part of the motor cortex and is located in the ventrolateral prefrontal cortex

Primary motor cortex (Brodmanns area no. 4)

responsible for execution of all voluntary body movements (i.e. muscle movement) and is located in the pre-central gyrus - different regions of the primary motor cortex control different parts of the body (it is somatotopically organized and the RH (right hemisphere) controls left side and LH (left hemisphere) controls the right - this is known as cross mapping - the primary motor cortex receives signals from proprioceptive information (meaning it is guided based on information about limb’s position in space) from the somatosensory cortex (which is located in the parietal lobe directly behind the primary motor cortex) - damage to one side of BA 4 (i.e. hemisphere- damage from something that causes atrophy or degeneration or damage of any sort - a lesion?) can result in hemiplegia

Lateral premotor cortex (BA 6)

modulates the activity of the primary motor cortex and is associated with acting on objects in ones external environment - the lateral premotor cortex receives stimulation from the parietal lobe via the dorsal route (visually?)

Supplementary motor cortex (medial premotor cortex/Broadmanns area no 6)

responsible for habitual actions that do NOT have a strong emphasis on monitoring the environment and being super attentive to the environment when doing a task (i.e. like dissociating when driving a car?) - deals with well learned actions and spontaneous movements; located above the corpus callosum on the interior fold of the hemisphere

TMS Study with the supplementary motor cortex (SMA)

→ applied TMS to three frontal areas (lateral PMC, Primary motor cortex, and SMA) across three conditions: 1. play a single note on the piano repeatedly; 2. play a scale on the piano 3. play a pre-learned song on the piano
→ saw that TMS applied to the Lateral premotor cortex had no impact on any of the three tasks that participants were asked to perform, however TMS on the SMA had an impact only on the complex task and TMS on the primary motor cortex impacted the scale and playing the learned piece

→ findings indicate that the primary motor cortex has a bring role in complex action that that you need the primary motor cortex along with the supplementary motor area when doing more complex motor movements and tasks; this also indicated that simple repetition of motion is not coded in any part of the motor cortex

Lesions in monkeys in the lateral pre-motor cortex

when a lesion is present in the lateral pre-motor cortex, it disrupts the coding based on the external stimulus they have been trained to respond to (cannot adequately choose between responses to a stimuli - engage in the same action no matter what) - cannot choose different motor actions
when asked to do a task of pulling a handle if blue but rotate if red, monkeys were unable to do this - they cannot change how they responded to the stimuli
cells in the lateral pre motor cortex respond more to external cues as opposed to internal voluntary movements (from single cell recordings)

pre-frontal cortex

(aka pre-cortical regions) attends to situation roles that govern movement though use of working memory to recall that representation of the rule to follow with the movement - more so for higher cognition as opposed to action/motor movements alone
→ pre-motor areas are big for planning and setting forth action/motor movements, however the PRE-FRONTAL CORTEX is responsible for selecting the path of action and ensuring that the selected action makes the most sense for the end goal of the action
→ single cell studies with monkeys in the pre-frontal cortex show that neurons respond to the “RULE” of the task and the goal of doing the action as opposed to the mechanical/movement mechanisms (the opposite is seen in the same study with the primary motor cortex
→ we also see that neurons in the PFC responds to anticipated sensory consequences (i.e an internal prediction of where the cursor was going → prediction of what is expected to be perceived after a voluntary action) of moving as opposed to the limb movements of moving a cursor

Imaging study by Frith et. al

study provides a good illustration of prefrontal function in humans

→ participants were asked to do two things (each for two studies) and the responses were measured in the medal and lateral cuts/parts of the anterior cingulate cortex and the dorsolateral prefrontal cortex (both of which are part of the prefrontal cortex)

For the first study:

1. read a given word

2. make your own word with certain letters

For the second study:

1. move finger that was touched

2. move whatever finger you wanted to

see that the anterior cingulate cortex was activated when responding to moving a finger when touched and when reading a given word (more externally involuntary action?) → also ACC showed very little activation in study two when asked to move the finger
see that the DLPFC showed greater activation for “free will” tasks (i.e. it was activated for tasks that were open to choice/decision making and willing intentional action - similar action with words and moving fingers

study proves that the DLPFC and ACC are likely involved with response selection and action as opposed to purely mechanics of motion (like whats seen in the motor cortex

pre-frontal damage

when one has damage to a pre cortical area, can see impairment in movement → impacts how an action is done and can make it more disorganized and not reflective of the goals of the action

preservation

repeating a movement and acting on something that’s already been performed (instance of damage to the PFC)

Utilization behavior

acting impulsively on objects in the environment that are irrelevant (instance of damage to the PFC)

Premotor theory of attention (Rizzolatti et al. 1987)

attention orientation reflects preparation of motor commands

ex: when screan has boxes 1-4, when cued with a seperate box underneath 1-4, if cued with 2, attention will orient to box 2 - if target appears in box one after cue, then the reparation of motor movement follows along same trajectory and have higher reaction time (because one is on the left side and attention is grasped visually more in the left side cuz its processed on the right or something)

basal ganglia

initiation and execution of an action (subcortical area)

cerebellum

responsible for coordination and motor control (of organs? - involuntary organ movement (subcortical region)

anterior cingulate cortex

associated with response competition - helps pick a response to enact?

SAS (supervisory attentional system) model

model that makes the distinction between automatic actions and action that requires attention and control - explains goal driven action and cognition

components: schemata and scripts, contention scheduling system, sensory information, effector systems
based on input from the supervisory attentional system and sensory systems, the contention scheduling system can select the most active schemata for the action

schemata and scripts are detailed information about actions (sets of stored actions = schemata - like folders in the brain with information - spongebob fire meme) and scripts are like the files inside a folder)
contention scheduling system selects schemata and scripts to be implemented
SAS then inputs personal goals and is responsible for activating and deactivating schemas - like taking folders out and putting the folder back

sensory information is info abt the environment

effector systems is movement of muscles

*think of SAS like this:

person at the head of office says “I NEED TO ATTACH TWO PIECES OF WOOD - WE HAVE THE FOLLOWING MATERIALS (which come from sensory information)” then CSS says “YESSIR” and runs to the filing cabinets and selects the schema and scripts necessary and reads them and inputs them into the computer named EFFECTOR SYSTEM then SAS tells CSS to STFU and CSS says “YESSIR” and turns Effector off
Without the SAS< CSS is like wtaf is happening and can’t really comprehend what folder they need from the filing cabinet and so CSS implements some random script based on sensory information which causes preservation cus schema can’t be deactivated by SAS and utilization cus CSS has no clue wut its doing

Free choice and consciousness EEG study - Libet et al. (1983)

in the study, Libet et al. monitored activity using EEG in the primary motor cortex and the SMA when asked to press a button whenever participants wanted and were then asked to report the time at which they were first aware they wanted to press the button (by looking at the clock) - when engaging in a motion, it might feel as though its immediate, however they wanted to know the time difference from making a decision to act/move to the time it would take to actually do the movement - they found that in their studies that therre was a spike in brain activity before making the movement; i.e. there was a mental representation BEFORE the participants were consciously doing the action? - or was it before the button was hit? - to Libet, free will is seen as an illusion since the signal to act was there before the person was made consciously aware to act.