Week 5 action

PMC and the affordance competition hypothesis?Action selection versus action specification? experiment illustrating competition?

At any one moment, opportunities for action —and their associated action plans— emerge in parallel Utility of action is continually assessed Action selection ("what") and action specification ("how") compete for selection in an interactive manner (This affordances competition hypothesis that we briefly mentioned at the beginning of the lecture So in essence the idea is that at any one moment As you scan your current environment There There's a number of opportunities for That's you Your brain might be representing Simultaneously These approaches for action Each of them will have an SOC Action Plan that might also be Emerging Parallel In other words, there's both Action selection Action specification. So what you could do And how you would do it that are being Automatically Got it. We're going to compete for selection so you at the end of the day You're going to select one action. But until you do that, you have this competing actions that are emerging in parallel. And, of course, how are you going to select The action at the end, likely through a series of competitions includes the value of the action and eventually when one action is selected. Now the other action or actions become inhibited) Remember where red and blue cues are in space, memory period, then color cue, then move joystick to that location (This is an experiment that's recorded from there so premotor cortex and I think illustrated this idea, quite nicely so the beginning of the trial. This by the way is recording from a population of neurons in the PMC. So the beginning of the trial. The monkey sees a couple of spatial cues that they then are going to keep in mind right so they might be moving a joystick towards one cue, or another, and there is a delay period. During that time, you see that the populations coding for those two coding for the movements towards those two possible spaces, they become simultaneously engaged. And then they get the next cue. So you can think of this as potential action plans that are being represented. And then they get the next cue that now tells them what is this first movements that they are going to do they're going to go to the red location. At that moment, what you see simultaneously is an increased engagement of that action plan that is now being called by color cue. Well the other action plan that had been previously engaged becomes dramatically inhibited relative to baseline. Finally, when they get a goal signal that's the moment that they're actually going to move the joystick, and you see that this now selected action plan becomes enhanced to even a greater extent than before. Alright, so this action plans once again they are often competing until there's a signal that's helps select one or another) Plan a movement to the red location Eventually one action wins and gets selected (others are inhibited)

pyramidal or corticospinal tracts (CST) endings? Corticomotor (CM) fibers? What are they used for?

CST fibers ending one is ending monosynaptically at alpha motor neurons (i.e. corticomotor (CM) fibers)OR at interneurons (most of them) • Corticomotor (CM) fibers promote greater dexterity: unique to human+ higher order primates crossed!! And what they do is that they promote this sort of finer movements and greater dexterity. Then what you'd be able to achieve otherwise. So this is an example of what happens with fibers this cortical motor fibers, when you do a precision grip versus just a power grip, and you see pretty clearly that it is only with when you do the precision grip that you see this increase spiking of this cortical motor of fibers, whereas the power grip.

What is coded in the motor cortex?

Direction of movement Force of movement Entire posture? (Sustained stimulation of motor cortex with micro-electrodes causes complex movements that lead to specific postures) well, we know that the direction of movements, is something that is codedd by a population of neurons, as well as the force of movements, actually, you know, the power of a grip for instance, that is determined in part by the number the sheer number of action potentials that are going into those fibers innervating a particular muscle, but something interesting and a little bit different from I think what's typically seen in textbooks. When talking about the, the primary motor cortex is that it's been found that if you stimulate population of a motor neurons, you can actually get more than just stereotypical movements and you can actually see this consistent return of the body to a specific posture, regardless of where you started. So that's what's plotted here so the difference traces that you see in a particular box for example, a. Those are our different starting positions for the monkey's arm and following a stimulation of a particular population of neurons, the monkey's arm, ended up in the same kind of location, essentially, you know, as a result of a particular complex posture that's seemingly this population of neurons was coding for. And so that's a little more complex than what you typically think about those neurons are representing.

What is perceiving/ thinking for?

Doing One reason might be that we need to act and interact with the environment in the most adaptable manner. And this idea was articulated actually in relation to perception by somebody named James Gibson, when he thought that when we first see objects in our environments that we are automatically processing the potential ways in which we could interact with those objects and what we would gain from doing so and at any one points, similar to our prior discussion regarding attention, something similar happens, regarding action at any one moment, there are several objects you could be interacting with and as we're going to be covering towards the end of this lecture, the mechanism of selection of actions. Also, a mechanism that involves competition and simultaneous updating of what is the most advantageous action at this moment, and what how should we be implemented towards what target.

Dorsal-dorsal role? optic ataxia? ventro-dorsal role? ideomotor apraxia? what did the patient with ideomotor apraxia do?

Dorsal-dorsal Role: reaching Lesion: Optic Ataxia (cannot reach object whilst still recognizing it); you've seen the video of a patient w/ this condition in the Vision lecture Ventro-dorsal Role: conceptual knowledge of actions Lesion: Ideomotor Apraxia(loss of knowledge of how to use an object) Okay, so in a little bit more detail that role of our dorsal dorsal Stream seems to be one of reaching and in fact, you Watch the patients in our lecture of higher order vision patient who was at a hospital bed who I could absolutely see that all Check that her doctor was showing her which couldn't reach and successful grab it, that person was suffering from optic ataxia. So she cannot reach the object while she fully recognized attend. in contrast What about our ventral dorsal stream where ventral dorsal stream Seems to be in evolved in our conceptual knowledge of actions. And this is by the way in contrast with our actions as they normally are executed so this will become clear in a moment. So lesions to a region called the left supramarginal gyrus, there's a part of that in your parietal lobe, they result in something called ideomotor apraxia which is a loss of knowledge of how to use an object, you're about to see a video about this and you hopefully clearly see this dissociation between Being able to use an object if you give the object to the patients versus asked Patient how they would use that tool. Okay So as you You can see This patient did not have have any trouble Using the comb but whenever you're asked to behave as They had a comb. Their hands their fingers became became comb as opposed to him being able to To pretend or hold at comb.

Further evidence for action plan competition?

During competition for action selection: cross talk between hemispheres; we force our hemispheres to decide on one goal (and another body of evidence for this ongoing competition between, between potential action plans and how and also the utility of selecting one. whenever there's competition for action selection. There's a lot of crosstalk between the hemispheres. And at some point, we force our hemispheres to decide on one goal) So, in these experiments, we have two conditions, where in one of them, there is this goal that's actually you can think of it as a common goal. Where you draw, essentially a sort of a mirror drawing with each of your separate hands. At the same time, so that's fairly easy while another goal. And now, much more challenging is that you draw one shape with one hand and another shape with the other hand. when the two actions are not congruent with one another right so there's a lot of interference and particularly if you have an intact corpus callosum okay so what happens when the corpus callosum has been dissected. In this case, there is actually an advantage for this callosotomy patients, there isn't this crosstalk. That is part of what causes this poor performance when you're trying to execute two disparate goals at the same time. And instead, they seem seemingly do just as well in the challenging condition with two distinct goals, as they do in the condition where the goal is the same. And so in essence that goes out to me seems to reduce this competition between the two hemispheres. And that leads to better performance and less interference. When executing these distinct actions Callosotomy: reduced competition-better performance (less interference) while executing two distinct actions simultaneously

Cortical motor system (M1) accessible? Extensively studied using Transcranial Magnetic Stimulation (TMS)? What is coded in the motor cortex?

Extensively studied using Transcranial Magnetic Stimulation (TMS) TMS single pulses to M1: produce visible(and easily quantifiable using EMG recordings)MEPs & muscle twitches TMS pulse to M1 Motor-evoked potential (MEP) recorded from hand muscle silver chloride ekectrodes that would sit along the fiber that you're interested in measuring the output from and what you see on the screen is exactly what energy recordings look like so they're very high frequency, sort of outputs they peak around 19 hertz. And that's that sort of fuzzy line blue lines that you see. So it turns out that if you deliver single pulses to the primary motor cortex, you get often a very pretty visible muscle twitches and depending on where you are, you are going to get at the level of sort of finger resolution for instance, you might get a twitch here and index finger, versus the ring finger, and as you move around those areas that are innervating those different digits. And so you get those visible muscle twitches and obviously if you want to have a more objective precise way of quantifying this, you can use once again this EMG electrodes, and you can measure something called multi evoked potentials or any piece, and this is what an MVP looks like so, after you deliver a single pulse about 20 milliseconds later, you'll get this very large multi microvolts fluctuation here that, you know, you can see with the naked eye, you don't really need to do much data pre processing to visualize this. And so, whenever investigators are trying to figure out certain types of TMS protocol so can we find the protocol to tonically excite or inhibit the cortex. That's precisely the type of tool that they use so they will test out their, their protocol in the motor cortex and follow that up with this any key record peripheral recordings,

Basal Ganglia function? input and output system?

Highly interconnected with prefrontal cortex - forming "corticostriatal loops", very segregated from other loops in the basal ganglia. thought to be essential for instrumental learning. learning what you should do to get a reward for example, or to avoid punishments. Motor movement. Caudate+Putamen: receive input from cortex Internal Globus Pallidus: sends output Basal ganglia dysfunction implicated in various motor disorders

Why do motor movements occur as a result of the basal ganglia?

Hyperkinetic disorder (too much movement): Huntington's In simplified form, there is either "too much" or "too little" excitation of the cortex (not enough "braking" by the output of the basal ganglia, internal Globus Pallidus), (in particular, actually the internal portion of the Globus pallidus, they serve as a brake for for movements so they either will allow information to flow through, and excite the thalamus and the cortex, does promoting movements, or they will actually serve as a break and not allow that flow of information to occur) which may result in: Huntington's chorea Hypokinetic disorder (too little movement): Parkinson's disease And you'll see them again today, but in essence you have this like rigidity of difficulty, starting a movement that is often successfully circumvented via Deep Brain Stimulation targeting, or this basal ganglia circuitry to increase the flow of information in this loop

Cause of Parkingsons disease? characteristics? treatment of Parkinson's?

Loss of neurons in the substantial nigra these produce dopamine and excite the caudate/putamen First described by James Parkinson (1817) as the shaking palsy Primary pathology identified as a loss of pigmented cells in the •substantia nigra ~70 years later reduced dopamine (DA) in striatum identified Characterized by: • Resting tremor Akinesia (loss of ability to produce volitional movements)Bradykinesia (slowness of movement; decreased blinking, •decreased facial expressions) dopaminergic inputs into the striatum which is critical for the basal ganglia to function properly, and promote movements initiation and so on. And here you can visualize the and compare the dopamine contents in the basal ganglia. The putamen is the main region that you can you see here, and you can compare the amount of dopamine is using paths. So, probably a dopamine agonist and you see that dopamine availability does reduce with, with age, but most importantly the, the reduction in Parkinson's is pretty dramatic. deep brain stimulation nd next we're going to see a pretty effective and incredible treatments for Parkinson's and that is deep brain stimulation. So, here, there are a couple actually different modalities of this of the brain solution for Parkinson's one of them targets the outputs of the basal ganglia, so the internal portion of the Globus pallidus and the another one targets targets the subthalamic nucleus. The net result is very similar. And here's an example of a patient who actually has a lot of tremors, and you see him initially with electrodes off and then of electrodes on. Greatly reduced the tremor.

Start with our output aka muscles: What innervates them? What do these neurons release? How are muscles organized? What types of signals do we need for the pair? What do gamma neurons do?

Muscles are activated by motor neurons Muscles are organized in antagonistic pairs Thus, to produce movement, we need: Excitatory signal to target muscle Inhibitory signal to antagonist muscle (via interneuron) So let's zoom in, at this at the outputs portion of our hierarchical cascade to start. Okay, So, at the outputs the portion of our motor system, we have our muscles working for us. They are innervated by a number of multiple fibers including alpha motor neurons which release acetylcholine, and that causes the muscles to contract. the muscles they are organizing this antagonistic pairs, so that is illustrated here nicely by the simultaneous interplay of the biceps and triceps. So, maybe already familiar with this, the idea is fairly simple. Whenever you are trying to show somebody your biceps, your biceps is engaged. How do you know that well you can see, if somebody, you know, has one, but you can also record from the muscle fibers that's called electromyography abbreviated as EMG, so it's a fairly simple recording is simply a pair of silver, silver chloride electrodes and so you know they're recording, let's say from two points that will capture they'll go along the fibers. And so just take the difference and that's what you'll see plotted here at the bottom of your graphs. And so when you're showing somebody, your biceps that would be the second figure here, you'd see that the biceps goes up fairly clearly whereas the triceps. In contrast does not. So, when this muscle is engaged, the other muscle that's antagonistic to is relaxed. So that means that you produce an intentional movement such as a biceps contraction, we need an excitatory signal to the target muscle. In this example, the biceps. And we also need an inhibitory signal to that antagonistic muscle, and that is going to occur in part due to this inter neuron that we're about to cover that we have gone through the spinal cord. Gamma motor neurons (proprioception) We also have gamma motor neurons not shown here, they're important for our sense of where our body is at any one moment, so they provide feedback about our body position, as well as movements.

brain machine interface?

Okay, so understanding precisely how the motor cortex is representing movements. It has profound significance for patients right so the ultimate dream for a lot of patients who have suffered lesions to the spinal cord, for example, is to have a brain machine interfaces that would allow them to be independent and would permit the accurate readout of their motor intentions, from electrodes, placed near their motor cortex. And so this is a, this paper was published. Now, a while ago it was in the early, 2000s was done in Caltech but in essence here, what you see is this grid of I believe it was a 10 by 10 array of of electrodes in the motor cortex So only like 100 points of contact and the patient was able to move the cursor in the different directions, shown here on your right, just by visualizing that by visualizing that movements. • 100-Unit electrode array in a monkey motor cortex• Record activity• Connect signals to a robot arm• Have the brain learn how to control the robot arm

Secondary motor areas: parietal cortex? Where does it connect to? How is it the opposite of premotor cortex?

Parietal areas: reciprocal PFC projections. Conceptual knowledge of actions; multi sensory control of actions Parietal stimulation: intention of movement (sometimes belief in having performed a particular action in the absence of action performance)

Disentangling Frontal vs Parietal roles in action goal? So, in essence, the question is, do prefrontal versus parietal neurons, do they care about the actual outcome, what you're trying to achieve or the goal, or do they care about the required movements to achieve that goal?

Pre Motor Cortex (PMC) stimulation: complex movement performance (without awareness or intention) Parietal stimulation: intention of movement (sometimes belief in having performed a particular action in the absence of action performance) Question: Do PFC vs. parietal neurons care about the action outcome (goal) or the required movement to reach the goal? Clever Strategy: short movies where a particular movement (A) could reach goal 1 or 2; conversely, goal (1) may be reached via movement A or B. Repetition suppression (fMRI analysis technique): a phenomenon that refers to the finding that if we process the same stimulus twice, BOLD is reduced (akin to "habituation"). Now we can look at "habituation" (or Repetition Suppression) of parietal and prefrontal cortex and compare whether they respond/habituate to outcomes (goals), movement, or both Inferior Parietal Lobe: responds to action outcomes Frontal Cortex Parietal Cortex Inferior Frontal Gyrus: responds to action movement (kinematics) So, in essence, the question is, do prefrontal versus parietal neurons, do they care about the actual outcome, what you're trying to achieve or the goal, or do they care about the required movements to achieve that goal. So how are you going to test for this, in healthy, participants. so the strategy that they use is actually very clever. And essentially what they did is they showed participants a series of shorts movies where they had this 2 by 2 cross the design so in some of the movies, you can think of this as there are two possible actions action. A or B, and the action a or b is, you know, moving the top of the box to the right or left. So those are two possible actions where the actual movement is different. And there are two goals, the goals are either to open this box or to close this box, and essentially they showed videos where, in some cases, this action opened the box and in some cases, this actually actually closed the box, and vice versa. And so by having every iteration of this possibilities. You can examine how these regions are responding to changes in goal versus changes in the actual movements. Side note Used technique analytical technique that's called repetition suppression so repetition suppression is actually a very intuitive analytical approach that you use analyze fMRI data, although I think you could use this with a number of different neural dependent measures but in essence, what happens is, let's say that you see the same stimulus twice so if you see a blue square now and you see a blue square 10 seconds later, the neurons that are responding to that blue square, when you see that for the second time, they don't respond to the same degree, that they respond the first time, and you can measure this attenuation in the magnitude of response the second and third and fourth time that you see the same thing. You can measure that relative attenuation using fMRI, so the bold response remember the correlates of neural activations. It sensitive to be something akin to habituation right with repeated exposure, the response becomes smaller and smaller. So, I think you know this is going by having this cross design. Now you can see, okay, if a neuron in the parietal cortex cares about the goal of opening up the box, you shouldn't matter if the box was open with the movements that went left or right. The goal was the same. And so if that's neuron or region of parietal cortex responds to goal the second time that they see a box now being open even if the movement is different, it should show repetition suppression which would mean that it sensitive to Goal not movements and that's exactly what they found. What's plotted here actually is the number of voxels basically regions showing repetition suppression so is a little bit counterintuitive because if you were to just measure the bold response for the number of regions that showed repetition suppression, you would expect to see more repretition suppression would mean less bold but here they plotted basically the number of voxels of parts of that region that are showing the evidence of repetition suppression and indeed what they see is that the parietal cortex is responding to outcomes so it shows repetition suppression, whenever you see the same goal. Whereas the frontal cortex that if your frontal gyrus is actually responding to the movement so regardless of whether it opened or closed the box is going to show repetition suppression to, let's say, a movement that to the left than the right.

Motor system hierarchy?

So let's first go over the hierarchal cascade. That is our motor system, so you can think of it. Of course this is a simplification but at the very top of this hierarchy that's once again very interactive, we have abstract goals and intentions that are represented in parts, thanks to prefrontal and parietal cortex. Goes to both premotor and supplementary motor cortex region, cerebellum, and basal ganglia. Then goes to the motor cortex. Then the brainstem. And at the very bottom we have the ultimate outputs, movements, for instance, and that is executed, through our muscles and the interactions between the muscles and the spinal cord. (all kind of interconnected)

What does the spinal cord do? example of a reflex? purpose of sensory+motor feedback system?

Spinal cord receives input from above (descending tracts from the brain) & from the periphery contain interneurons that support simple reflexes Okay, so now on to the spinal cord, the spinal cord is capable of supporting through this inter neuron system that we're about to cover it's a way of supporting simple reflexes. And this is an example of a powerful reflex that's the stretch reflex. So if somebody hits your knee with a hammer. The reflex goes as follows. So first, your quadriceps, is stretched. When that happens, we have this sensor that's a stretch receptor called a muscle spindle that senses that that quadriceps muscle has been engaged. It immediately thinks, oh, something is going on, and it sends a signal to the sensory neuron (dorsal root), that's going to hit the spinal cord. The next thing that happens is there's an inter neuron, located in the spinal cord, that's going to engage this alpha motor neuron as a (ventral route), which in turn is going to contract the quadricep So, in essence, by having this one movements going in one direction, and we have this clever feedback system that's completely automatic it does not clearly engage your brain at all, that is going to put correct for that muscle change. And so, why would this be useful. Well, it helps you maintain a posture and just compensates or provides stability, whenever there are unexpected perturbations on the body.

How does the brain innervate the spinal cord i.e. the two motor pathways? What are the different tracts? what do they support?

The brain innervates the spinal cord via pyramidal and extrapyramidal tracts o that's pretty cool. So to our brainstem. We have essentially two types of motor pathways so one of them is that we'll cover in much more detail later in the lecture is our pyramidal tracts or a cortical spinal tract that's the first one, shown on the left, but in addition to that, we also have what's called extra pyramidal tracks. And why are they called this Well, you see that in the case of the cortical spinal tracts that when the fibers cross through the medulla they form there in this shape that is pyramid like, whereas the other fibers actually pyramidal ones, they don't cross it through that area?? Pyramidal tract for fine control extrapyramidal tracts--> rubrospinal (stance/Gait) tectospinal(orientating (automatic attention superior colluculus) vestibulospinal( balance) reticulospinal (startle)

What else does the cerebellum do?

if you do a resting state functional connectivity analysis very much like the ones, originally done to identify those large scale neural networks that would have been on cortex, you will find essentially all of those networks recapitulated in the cerebellum, and you'll also find the very specific portion of the cerebellum engaged during tasks that go much beyond the motor tasks so working memory tasks and emotion processing tasks as shown here, and the precise significance of the contribution of the cerebellum to this processes remains very much an area of active study.

Cerebellum function? neurons in cerebellum kind and percent?

jean Pierre found Showed that lesions to the cerebellum (in dogs) caused uncoordinated movement Contains 75% of all neurons Acts as a "comparator" ofintended state and current state/action: adjusts for errors and provides feedback Lesions to it produce: •Ataxia (difficulty maintaining balance) Hereditary Cerebellar Degeneration Loss of accurate comparisons between motor command, on-line feedback and timing (And so, this is reserved for this related to what we mentioned the prior slide difficulty in maintaining balance or coordination, as well as the loss of this very important comparator, always happen in comparison that allows you to adjust for for any errors, in your performance and so here we have an example of a patient that has cerebellar degeneration. And, and you see that he was going to be asked to follow certain movements and that he's able to do that, if they're relatively slow, but as soon as that those movements kind of pick up. You're going to notice that he might overshoot, and he does not correct, that in the subsequent trial) Something perhaps of notes here as well, is that when when somebody drinks alcohol the cerebellum is one of the most impacted structures that's part of why one of the tests that the police does is related to like touch your nose and that's exactly the type, fine movement that the cerebellum would allow you to, to precisely perform.

Huntingtons chorea?

no caudate Rare autossomal dominant disease (onset: 40 y) Characterized by: Involuntary movement Dementia Depression (Caudate much interconnected with prefrontal cortex and similar to what you sometimes have as a result of certain prefrontal lesions that actually predispose you to the development of major depression, you have something similar that happens here, and this is, by the way, it's a common theme where for almost any prefrontal lesion resulting behavioral deficits you have a mirror in the, in the basal ganglia where you could get some very similar deficits with, with a lesion in a particular part of basal ganglia that's connected with a particular party frontal cortex)

secondary motor areas: prefrontal? What are the subdivisions of the premotor? connections of the premotor cortex? supplementary cortex interconnection? function? lesion results in?

premotor and supplementary motor areas Pre Motor Cortex (PMC): reciprocal parietal cortex projections. May contain "abstract" action maps regardless of effector used (e.g. grasp action) PMC intracranial stimulation: complex movement without awareness or intention (the premotor cortex and premotor cortex has two subdivisions, the dorsal premotor pad, as well as the ventral premotor or pmv. And keep in mind that this is always true when we talk about hypertrophy projects, but they have this region has really excessive interconnections with parietal cortex. Okay, so what we understand that this region can do is to maintain this abstract action maps, regardless of what the factor or muscle group is. And whenever you stimulate premotor cortex, what you get as a result is a complex movements that occur without any awareness of orientation. So the patient may be surprised that that move that they just perform that movements of following a PMC simulation) Important for sequential, complex Supplementary Motor Area (SMA): interconnected with medial PFC- input into motor system likely governed goals, preferences. Important for sequential complex plans and goals--> hand assignment SMA Lesions: • can't use 2 hands together for two- step action Alien Hand syndrome supplementary motor area is actually is more interconnected with medial prefrontal cortex compared to this more lateral premoter cortical region that we just discussed. And for that reason, as we'll cover in great detail in our emotional lecture, this region will just have more inputs that's related to current values, preferences, and general general motivational states compared to a premotor cortex for instance. But in addition to that, it also is important for complex sequences and complex motor plans, as well as a goal and hand assignments. And so they just should sma they result in just a difficulty in using two hands together for a two step action. So actually, your book gives a good example of this, where you know, if the two actions include open a drawer with hand one and retrieve an object with hand two, that's what's efficient in SME lesional tend to do is open the drawer with hand one and then do the same thing with hand two, as opposed to the sequence that would entail a different action following the completion of the first goal. And it can also result in an alien syndrome, we've seen a video of a patient who had this who remember that neuro anatomically, we are indeed very close to the corpus callosum, right? Because we're in this more medial region, where there's a lot of interaction between the hemispheres, which sometimes can be it should be inhibitory, I should be able to have this complex action plan successfully executed.

dorso-dorsal and ventro-dorsal stream?

we actually can further subdivide the dorsal stream into dorsal dorsal stream and ventral dorsal stream and these are the take home the most important points regarding this subdivision. So for our dorsal dorsal stream, it seems to be implicated in reaching and simple grasp types. of action exits the occipital lobe and we reached this stages of higher order vision if you will and more complex representations. And so, we know that we have dorsal and ventral streams. And when we think of multi action, we actually can further subdivide the dorsal stream into dorsal dorsal stream and the ventral dorsal stream and these are the take home the most important points regarding this subdivision. So, for our dorsal dorsal stream, it seems to be implicated in reaching and simple grasp types of actions (reaching, simple grasps, locations), whereas our ventral dorsal stream is involved in complex grasps and interactions with objects as well as knowledge about tools and about, about the actions that involve objects (complex grasps, tools). And finally, we know the ventral stream is Same that we already covered. So it's implicated in object recognition and conceptual knowledge about objects.