Low-dimensional and monotonic preparatory activity in mouse anterior lateral motor cortex

“Neurons in the frontal and parietal cortex and related brain regions show persistent or ramping changes in spike rate during different types of short-term memory, including motor planning (Fuster and Alexander, 1971; Kubota and Niki, 1971; Bruce and Goldberg, 1985; Miyashita, 1988; Funahashi et al., 1989; Riehle and R…”

“Neurons in the frontal and parietal cortex and related brain regions show persistent or ramping changes in spike rate during different types of short-term memory, including motor planning (Fuster and Alexander, 1971; Kubota and Niki, 1971; Bruce and Goldberg, 1985; Miyashita, 1988; Funahashi et al., 1989; Riehle and R…”

“Such sequences have been reported during motor planning and other kinds of short-term memory in the premotor cortex, the mPFC, the posterior parietal cortex, and the hippocampus of rodents (Harvey et al., 2012; Buzsáki and Moser, 2013; Murakami et al., 2014; Schmitt et al., 2017).”

“Neurons in the frontal and parietal cortex and related brain regions show persistent or ramping changes in spike rate during different types of short-term memory, including motor planning (Fuster and Alexander, 1971; Kubota and Niki, 1971; Bruce and Goldberg, 1985; Miyashita, 1988; Funahashi et al., 1989; Riehle and R…”

“, 2010), the frontal eye field (FEF; Bruce and Goldberg, 1985; Hanes and Schall, 1996), the parietal cortex (Gnadt and Andersen, 1988; Maimon and Assad, 2006), the striatum (Alexander and Crutcher, 1990; Ding and Gold, 2010), the superior colliculus (Wurtz and Goldberg, 1972), the motor-related thalamus (Tanaka, 2007)…”

“We used four transgenic mouse lines: PV-IRES-cre (RRID: IMSR_JAX:008069; Hippenmeyer et al., 2005), Olig3-cre (Vue et al.”

“, 2010), the frontal eye field (FEF; Bruce and Goldberg, 1985; Hanes and Schall, 1996), the parietal cortex (Gnadt and Andersen, 1988; Maimon and Assad, 2006), the striatum (Alexander and Crutcher, 1990; Ding and Gold, 2010), the superior colliculus (Wurtz and Goldberg, 1972), the motor-related thalamus (Tanaka, 2007)…”

“The detailed structure of the activity trajectories during motor planning predicts parameters of the future movements (Shenoy et al., 2013; Li et al., 2016).”

“Neurons in the frontal and parietal cortex and related brain regions show persistent or ramping changes in spike rate during different types of short-term memory, including motor planning (Fuster and Alexander, 1971; Kubota and Niki, 1971; Bruce and Goldberg, 1985; Miyashita, 1988; Funahashi et al., 1989; Riehle and R…”

“, 2010), the frontal eye field (FEF; Bruce and Goldberg, 1985; Hanes and Schall, 1996), the parietal cortex (Gnadt and Andersen, 1988; Maimon and Assad, 2006), the striatum (Alexander and Crutcher, 1990; Ding and Gold, 2010), the superior colliculus (Wurtz and Goldberg, 1972), the motor-related thalamus (Tanaka, 2007)…”

“Neurons in the frontal and parietal cortex and related brain regions show persistent or ramping changes in spike rate during different types of short-term memory, including motor planning (Fuster and Alexander, 1971; Kubota and Niki, 1971; Bruce and Goldberg, 1985; Miyashita, 1988; Funahashi et al., 1989; Riehle and R…”

“In nonhuman primates, preparatory activity has been detected in the primary motor cortex (Tanji and Evarts, 1976; Riehle and Requin, 1989; Alexander and Crutcher, 1990), the premotor or supplemental motor cortex (Riehle and Requin, 1989; Alexander and Crutcher, 1990; Churchland et al.”

“Neurons in the frontal and parietal cortex and related brain regions show persistent or ramping changes in spike rate during different types of short-term memory, including motor planning (Fuster and Alexander, 1971; Kubota and Niki, 1971; Bruce and Goldberg, 1985; Miyashita, 1988; Funahashi et al., 1989; Riehle and R…”

“, 2010), the frontal eye field (FEF; Bruce and Goldberg, 1985; Hanes and Schall, 1996), the parietal cortex (Gnadt and Andersen, 1988; Maimon and Assad, 2006), the striatum (Alexander and Crutcher, 1990; Ding and Gold, 2010), the superior colliculus (Wurtz and Goldberg, 1972), the motor-related thalamus (Tanaka, 2007)…”

“Such sequences have been reported during motor planning and other kinds of short-term memory in the premotor cortex, the mPFC, the posterior parietal cortex, and the hippocampus of rodents (Harvey et al., 2012; Buzsáki and Moser, 2013; Murakami et al., 2014; Schmitt et al., 2017).”

“2), we performed hierarchical bootstrapping: first, we randomly selected animals with replacement; second, we randomly selected sessions within an animal with replacement; and finally, we randomly selected trials within the session with replacement (Efron and Tibshirani, 1994; van der Leeden, 2008; Aarts et al., 2014;…”

“These findings are consistent with a circuit in which FS neurons pool activity from local pyramidal neurons (Kerlin et al., 2010) and inhibit the ramping-down cells.”

“Neurons in the frontal and parietal cortex and related brain regions show persistent or ramping changes in spike rate during different types of short-term memory, including motor planning (Fuster and Alexander, 1971; Kubota and Niki, 1971; Bruce and Goldberg, 1985; Miyashita, 1988; Funahashi et al., 1989; Riehle and R…”

“The endpoints of trajectories could reflect optimal “initial conditions” for specific planned movements (Churchland et al., 2006).”

“The ALM is required for motor planning The ALM (relative to bregma: anterior, 2.5 mm; lateral 1.5 mm; Komiyama et al., 2010) is required for motor planning in the tactile delayed-response task (Guo et al.”

“These activity trajectories occupy a low-dimensional manifold (Gao and Ganguli, 2015).”

“Optogenetic manipulations have provided evidence that preparatory activity in the ALM underlies motor planning (Guo et al., 2014a; Li et al., 2015, 2016; Svoboda and Li, 2017).”

“High spike-count correlation among cells with the same coding preference is consistent with data from FEFs of primates during motor planning (Constantinidis and Goldman-Rakic, 2002).”

“, 2010), the frontal eye field (FEF; Bruce and Goldberg, 1985; Hanes and Schall, 1996), the parietal cortex (Gnadt and Andersen, 1988; Maimon and Assad, 2006), the striatum (Alexander and Crutcher, 1990; Ding and Gold, 2010), the superior colliculus (Wurtz and Goldberg, 1972), the motor-related thalamus (Tanaka, 2007)…”

“Such sequences have been reported during motor planning and other kinds of short-term memory in the premotor cortex, the mPFC, the posterior parietal cortex, and the hippocampus of rodents (Harvey et al., 2012; Buzsáki and Moser, 2013; Murakami et al., 2014; Schmitt et al., 2017).”

“, 2010), the frontal eye field (FEF; Bruce and Goldberg, 1985; Hanes and Schall, 1996), the parietal cortex (Gnadt and Andersen, 1988; Maimon and Assad, 2006), the striatum (Alexander and Crutcher, 1990; Ding and Gold, 2010), the superior colliculus (Wurtz and Goldberg, 1972), the motor-related thalamus (Tanaka, 2007)…”

“hearing loss experienced by C57BL/6 mice (Ison et al., 2007).”

“Neurons in the frontal and parietal cortex and related brain regions show persistent or ramping changes in spike rate during different types of short-term memory, including motor planning (Fuster and Alexander, 1971; Kubota and Niki, 1971; Bruce and Goldberg, 1985; Miyashita, 1988; Funahashi et al., 1989; Riehle and R…”

“, 2005), Olig3-cre (Vue et al., 2009), Ai32 [Rosa-CAG-LSL-ChR2(H134R)-EYFP-WPRE, RRID:IMSR_JAX: 012569; Madisen et al.”

“, 2010), the frontal eye field (FEF; Bruce and Goldberg, 1985; Hanes and Schall, 1996), the parietal cortex (Gnadt and Andersen, 1988; Maimon and Assad, 2006), the striatum (Alexander and Crutcher, 1990; Ding and Gold, 2010), the superior colliculus (Wurtz and Goldberg, 1972), the motor-related thalamus (Tanaka, 2007)…”

“, 2010), the frontal eye field (FEF; Bruce and Goldberg, 1985; Hanes and Schall, 1996), the parietal cortex (Gnadt and Andersen, 1988; Maimon and Assad, 2006), the striatum (Alexander and Crutcher, 1990; Ding and Gold, 2010), the superior colliculus (Wurtz and Goldberg, 1972), the motor-related thalamus (Tanaka, 2007)…”

“Some of these mice were in addition used for optogenetic experiments not described in this paper (Inagaki et al., 2017).”

“Perturbations are either robustly ignored (top), or flip the dynamics so that the end points are reversed (bottom) [142, 138].”

“This organization could ensure that preparation does not trigger movement [54,55], and may help protect previous motor memories [56].”

“Other frontal cortical regions—similarly to the frontal premotor region we studied—have been found to exhibit relatively low dimensional activity that mimics task complexity, in contrast to higher dimensional sensory areas (Brincat et al., 2018; Inagaki et al., 2018).”

“Spike rates in individual ALM neurons often increase or decrease during a trial in ramp-like patterns (Guo et al., 2014b; Inagaki et al., 2018; Li et al., 2015).”

“Lower dimensional representations that are consistent with task dimensionality – as reported in higher-order cortical areas [86,87] – coemerged in both cerebellum and cortex as mice gained task expertise.”

“ALM activity can be decomposed into several activity modes that capture a large proportion of cortical activity (Figure 1) (Li et al., 2016; Inagaki et al., 2018).”

“This is consistent with recent experiments on rodents (21, 22) that show that neural trajectories are low-dimensional, with a time-varying component that is dominated by ramping activity (46, 48).”

“In the mouse, the anterolateral motor (ALM) cortex has premotor-like properties, particularly in behavioral tasks involving motor planning during a temporal delay (Guo et al., 2014; Inagaki et al., 2018).”

“Both frontal and posterior cortical areas have been implicated in delay activity related to short-term memory (Goard et al., 2016; Guo et al., 2014; Inagaki et al., 2018; Kamigaki and Dan, 2017; Gilad et al., 2018; Harvey et al., 2012; Morcos and Harvey, 2016; Siegel et al., 2015; see also review by Sreenivasan and D’…”

“In the mouse, M2 is implicated as essential in several discrete motor behaviors, including licking (Chen et al., 2017; Allen et al., 2017; Inagaki et al., 2018) and in a lever press task (Makino et al., 2017).”

“Despite previous work [29,30] showing that the ALM supports persistent activity, the mechanism underlying the emergence of the discrete attractors remained unclear.”

“cortex, a region strongly engaged during decision-making (Guo et al., 2014, 2017; Inagaki et al., 2018) as well as the primary visual cortex (V1).”

“On the other hand, neural networks, whether adaptive or hard-wired, have structures that shape population neural dynamics onto a low dimensional manifold, where nonrandom and ordered activity patterns emerge (Ganguli et al., 2008; Harvey et al., 2012; Inagaki et al., 2018).”

“0) in head-fixed mice performing an auditory delayed response task (Inagaki et al., 2018).”

“Our model thus predicts that working memory may share common activation patterns across sensory modalities, which is partially supported by cortical recordings during a memory-guided response task ( Inagaki et al., 2018 ).”

“Similarly to neurons in the primate motor cortex [28, 29, 30], the activity of many neurons in ALM ramps slowly during motor preparation and is selective to future actions [21, 31, 32].”

“Recordings Electrophysiological recordings were made with Neuropixels probes (Phase 3A and B) in head-fixed mice performing an auditory delayed response task (Inagaki et al., 2018).”

“ALM plays an important role in the planning and execution of licking (Komiyama et al. 2010; Guo, Hires et al. 2014; Li et al. 2015; Inagaki et al. 2018), as reflected by the presence of neurons whose firing rates are modulated before the onset of licking (defined as “preparatory” neurons) (Guo, Hires et al.”

“51,52 Neural Data Analysis All analysis of neural data was performed on the second psychometric testing session when the following stimuli were presented (% sucrose in mixture): 100, 75, 60, 40, 25, 0.”

“Mice were trained to perform directional licking (lick-left or lick-right) depending on the frequency of a series of pure tones presented to the animal (12-kHz tones instruct lick-left; 3-kHz tones instruct lick-right) to obtain water rewards 32 (Fig.”

“These three directions in activity space, together with a fourth direction that captures non-selective ramping activity during the delay epoch (Li et al., 2016; Inagaki et al., 2018), account for 87.”

“…2016; Finkelstein et al. 2021; Inagaki et al. 2022; Daie et al. 2023; Wang et al. 2021; Chen et al. 2024), as it is strongly correlated with the animal’s upcoming decision (Inagaki et al. 2019) and remains stable throughout the delay period (Li et al. 2016; Inagaki et al. 2018; Daie et al. 2023).”

“The projection to the first vector resulted in nonselective ramping activity, and this vector was referred to as the ramping mode (Inagaki et al., 2018).”

“In particular, M2 units show preferential activation for cues/actions based on egocentric location and active inhibition for opposing cues/actions (Inagaki et al., 2018; Wei et al., 2019).”

“19,26 41–43 One important distinction between our results and this prior work is that previous studies all looked at trained tasks in which the anticipated response was well known.”

“The most commonly used behavior test for “preparatory activity” in mice is auditory and tactile delayed-response tasks (Inagaki et al., 2018).”

“We next deployed a well-established mouse behavioral paradigm, delayed two-alternative forced choice (d2AFC), which was used to study motor planning in mouse Guo et al., 2014b ; Inagaki et al., 2018 , in HABITS to demonstrate the performance of our system ( Figure 2 ).”

“…performs worse at high frequencies and low sound levels in ahl B6 mice C57BL/6 mice are commonly used in behavioral experiments involving acoustic stimuli (Inagaki et al., 2018; Guo et al., 2019; Breton-Provencher et al., 2022), but our results suggest that these animals process sounds differently.”

“Finally, our approach did not clearly identify the anterolateral motor area (ALM; Chen et al., 2017 ; Inagaki et al., 2018 ; Li et al., 2015 ) within M2, although this may be a consequence of the time period analyzed; a time window targeted to the period of withdrawal and water consumption might…”

“With this evidence taken into account, our findings support that M2 is involved in a locomotion inhibition mechanism utilized in decelerating but not in accelerating under similar conditions.”

“…in M2/ALM during performance of learned lick responses reveals neuronal activity that precedes and predicts the performance of licks (Komiyama et al. 2010; Li et al. 2016; Inagaki et al. 2019, 2018; Chen et al. 2017; Guo et al. 2014; Erlich, Bialek, and Brody 2011; Zagha, Ge, and McCormick 2015).”

“Initial training and task structure were similar to previous studies ( Guo et al., 2014a ; Guo et al., 2014b ; Inagaki et al., 2018 ) and shown in Figure 1A.”

“Neural activity in ALM links sensory and motor encoding through preparatory firing that begins during stimulus presentation or during the delay period and persists until movement onset ( 5 – 9 ).”

“Preparatory ac-8 tivity in this setting resembles a population ramp to threshold (41).”

“We used a model-based approach (7, 18) to analyze an open-source dataset (12, 17) containing preprocessed extracellular recordings from the ALM cortex of mice performing a delayed response task.”

“We speculate that these additional dimensions reflect neural computations that are temporally structured at timepoints near movement, but not instantaneously correlated with them, such as motor planning and decision making (Briggman et al., 2005; Inagaki et al., 2018; Svoboda and Li, 2018).”

“Both somatosensory 42,43 and motor 5,44 cortices contain neurons with mixed touch-movement selectivity, raising the question of whether these neurons function to bridge somatosensory and motor assembly activity.”

“To test if the underlying neural code for time was based on sequential firing, we employed a modified version of a previously described method 32 .”

“A detailed description of data collection procedure can be found in Inagaki et al. (Inagaki et al., 2018; Inagaki et al., 2019).”

“Then, we estimated the selectivity of a neuron from data in the same way as the previous studies (Li et al., 2015; Inagaki et al., 2018).”

“Hence, peak 4 is likely to reflect participation of the primary somatosensory cortex in motor preparatory activity, often observed in higher motor cortices (12–14).”

“…can direct a focused laser beam to specified positions on the skull (Guo, Li, et al. 2014; Li et al. 2016; Heindorf, Arber, and Keller 2018; Inagaki et al. 2018; Pinto et al. 2019; Keller, Roth, and Scanziani 2020; Esmaeili et al. 2021; Voitov and Mrsic-Flogel 2022; Pinto, Tank, and Brody…”

“1 A ; Guo et al., 2014; Inagaki et al., 2018).”

“Following a brief delay epoch, a go cue instructed mice to perform a directional tongue movement 10,58,59 ( Fig.”

“Therefore, this global regulation is unlikely to originate directly from frontal cortical pre-motor areas 24-26 since frontal cortices have a very high degree of symmetry for both ipsilateral and contralateral projections 57 .”

“…Desimone 1996; Romo et al. 1999; Miyashita and Chang 1988; David J. Freedman and Assad 2006; D. J. Freedman et al. 2001) and rodents (Baeg et al. 2003; Fujisawa et al. 2008; Erlich, Bialek, and Brody 2011; Harvey, Coen, and Tank 2012; Inagaki et al. 2018, 2019; Goard et al. 2016; Liu et al. 2014).”

“…behavioral, and cognitive features (Ceballo et al., 2019; Erlich et al., 2011; Fischer et al., 2020; Goard et al., 2016; Guo et al., 2014; Harvey et al., 2012; Inagaki et al., 2018; Licata et al., 2017; Raposo et al., 2014; Yang & Zador, 2012; Zhou & Freedman, 2019; Znamenskiy & Zador, 2013).”

“Mice were trained to perform an auditory-cued directional licking task ( Figure 1A ; Guo et al., 2014b ; Inagaki et al., 2018 ) with two target lickports approximately equidistant from the mouth ( Figure 1A and B ).”

“These preparations permit large-scale recordings with two-photon calcium imaging 7–9 and high-density electrophysiology 6,10,11 , and enable causal interrogation of neural circuits using optogenetics 12–14 .”

“1A; 39, 40).”

“11 However, how sensory processing, motor preparation, and motor execution occur during sequences of movements flexibly constructed on-the-fly remains incompletely understood.”

“51,52 Neural Data Analysis All analysis of neural data was performed on the second psychometric testing session when the following stimuli were presented (% sucrose in mixture): 100, 75, 60, 40, 25, 0.”

“For example, the anterior lateral motor cortex (ALM) is involved in decision-making through the deliberation of appropriate actions based on sensory evidence [2-8].”

“We next defined CD ramp as the direction that captures trial-type independent increases or decreases in preparatory activity between the onset of the stimulus and the go cue in DR trials 61,62,67,68 .”

“In addition to potentially explaining the functionality of piriform cortex, attractor dynamics have been used to explain previous experimental work regarding persistent activity of certain neurons in monkeys [8, 9] and mice [10] during working memory tasks.”

“Studying the underlying low-dimensional representations of the recorded neural spikes is of great significance for understanding mechanisms of cognitive processes, such as fictive locomotion [3], motor planning [12], the Olfaction system [27], auditory stimulus responses [2].”