The following table summarizes the components of total stock-based compensation expense included in the condensed consolidated statements of operations and comprehensive loss (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Research and development	$	512	$	613	$	1,747	$	2,044
General and administrative		623		943		2,413		2,536
Total stock-based compensation expense	$	1,135	$	1,556	$	4,160	$	4,580

As of September 30, 2023, there was $3.7 million of total unrecognized stock-based compensation related to outstanding equity awards, which is expected to be recognized over a weighted average remaining amortization period of 1.5 years.

The fair value of stock options granted during the periods indicated was estimated using the Black-Scholes option pricing model, based on the following assumptions:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Exercise price	$0.98	$1.66 - $2.19	$0.89 - $1.53	$1.53 - $2.45
Expected volatility	77.5% - 83.1%	78.6% - 81.7%	77.5% - 83.1%	78.6% - 81.7%
Risk-free rate	4.23% - 4.24%	2.62% - 4.15%	3.59% - 4.24%	1.41% - 4.15%
Expected term (years)	5.5 - 7.0	5.5 - 7.0	5.5 - 7.5	5.5 - 7.5
Expected dividend yield	0%	0%	0%	0%